ELECTROMECHANICAL ACTUATOR

专利摘要:
An electromechanical actuator (1) comprises a first electric motor (3), a first motion conversion mechanism (6), a second motion conversion mechanism (8), and a rotation restriction mechanism (11) for the second motion conversion mechanism (8). The first motion conversion mechanism (6) comprises a first element (29) which is rotated by an output of the first electric motor (3) and a second element (31) which is fixed to the first element (29). The second motion conversion mechanism (8) comprises a third member (33) which is movable integrally with the first member (29) and a fourth member (35) which is attached to the third member (33). The rotation restriction mechanism (11) is configured to be able to selectively restrict and rotate the fourth member (35) depending on the motion of the third member (33).
公开号:FR3020431A1
申请号:FR1553639
申请日:2015-04-23
公开日:2015-10-30
发明作者:Masanori Hirai；Masayoshi Ueyama
申请人:Nabtesco Corp；
IPC主号:

专利说明:

[0001] ELECTROMECHANICAL ACTUATOR REFERENCE TO RELATED APPLICATION This application is based on and claims the priority of Japanese Patent Application No. 2014-089490, filed April 23, 2014.
[0002] BACKGROUND OF THE INVENTION The present invention relates to an electromechanical actuator that includes a motion conversion mechanism, such as a screw mechanism, and converts a rotational driving force, which is outputted by a electric motor, into a linear drive force for outputting the linear drive force.
[0003] A conventional electromechanical actuator includes an electric motor and a screw mechanism and is used in various fields, such as aircraft. Such an electromechanical actuator converts a rotational driving force, which is outputted by the electric motor, into a linear driving force via the screw mechanism and outputs the linear driving force.
[0004] The electromechanical actuator moves an output portion in a straight line relative to a housing to drive a device. The electromechanical actuator is easy to maintain with respect to a hydraulic actuator, which is driven by the supply of hydraulic oil. This is the advantage of the electromechanical actuator. US Patent Application Publication No. 2007/0051847 discloses an electromechanical actuator that includes a ball screw mechanism and two electric motors such that a rod moves linearly. Each electric motor is coupled to the ball screw mechanism. The ball screw mechanism converts the rotation, which is output by the electric motors, into a linear movement (of the output portion) of the rod.
[0005] U.S. Patent No. 5,144,851 discloses an electromechanical actuator that includes an electric motor, a planetary gear mechanism, and two ball screw mechanisms. One of the ball screw mechanisms surrounds the other ball screw mechanism. This structure allows an output of the electric motor to be selectively distributed to the ball screw mechanisms via the planetary gear mechanism. When the electric motor rotates one of the ball screw mechanisms (the output portion of) the rod moves in an axial direction. U.S. Patent No. 4,637,272 discloses an electromechanical actuator that includes a ball screw and ball nuts. Each ball nut can be rotated by an output of a corresponding electric motor. This allows (the exit portion of) the ball screw to move in an axial direction when any of the electric motors are driven. SUMMARY OF THE INVENTION In the electromechanical actuators above, the screw mechanism may be jammed (jammed) due to seizure or scuffing. Such jamming prevents the output portion from moving forward or backward relative to the housing. However, US Patent Application Publication No. 2007/0051847 discloses a structure which comprises only a ball screw mechanism serving as a screw mechanism. A jamming therefore prevents the output portion from moving forward or backward relative to the housing. U.S. Patent No. 5,144,851 discloses a structure in which the planetary gear mechanism distributes an output of the electric motor to two screw mechanisms (ball screw mechanisms). In this structure, when one of the ball screw mechanisms is jammed, the other ball screw mechanism can be driven to move the rod in an axial direction. However, the structure disclosed in US Patent No. 5,144,851 is not configured to actively control which ball screw the output of the electric motor is distributed. In this case, it is more desirable to distribute the output to the ball screw so that the rod can move in a more secure manner even in case of jamming.
[0006] The structure disclosed in US Patent No. 4,637,272 includes clutch mechanisms in addition to a number of electric motors. Each clutch mechanism connects and disconnects a power transmission line between a corresponding electric motor and a corresponding ball screw mechanism. The structure is therefore complex.
[0007] Accordingly, an object of the present invention is to provide an electromechanical actuator which has a simple structure and moves an actuating part, such as a rod, in a more secure manner even in case of jamming. To achieve the above objective, one aspect of the present invention is an electromechanical actuator that includes a first electric motor, a first motion conversion mechanism, a second motion conversion mechanism, and a rotation restriction mechanism. for the second motion conversion mechanism. The first motion conversion mechanism includes a first screw and a first nut that is attached to the first screw. The second motion conversion mechanism includes a second screw and a second nut that is attached to the second screw. The first motion conversion mechanism comprises a first element and a second element. The first element comprises one of the first screw and the first nut. The first element is rotated by an output of the first electric motor. The second element comprises the other one of the first screw and the first nut. The second motion conversion mechanism comprises a third element and a fourth element. The third element comprises one of the second screw and the second nut. The third element is movable integrally with the first element. The fourth element comprises the other of the second screw and the second nut. The rotation restriction mechanism is configured to be able to selectively perform an operation that restricts the rotation of the fourth member as the third member moves, and an operation that allows rotation of the fourth member when the third member moves. . Each motion conversion mechanism can be formed using one of a roller screw and a ball screw. Preferably, the electromechanical actuator further comprises a gear that is rotated upon receiving the output of the first electric motor, and teeth that are configured to mesh with the gear and rotate integrally with the gear. the first element. The teeth form flutes extending in an axial direction of the first member. Preferably, the electromechanical actuator further comprises a rotation stop mechanism which restricts the rotation of the second member. Preferably, the electromechanical actuator further comprises a first hollow shaft. The first shaft comprises the first element and the third element which are arranged in a straight line.
[0008] More preferably, the electromechanical actuator further comprises a second shaft that is inserted into the first shaft and a third shaft that surrounds the first shaft. The first nut that functions as the first member and the first member that functions as the second member are respectively disposed on an inner circumference of the first shaft and an outer circumference of the second shaft. The second screw that functions as the third member and the second nut that functions as the fourth member are respectively arranged on an outer circumference of the first shaft and an inner circumference of the third shaft.
[0009] Preferably, the electromechanical actuator further comprises a housing which houses the fourth member and a bearing unit which is held by the housing and supports the fourth member. The bearing unit comprises a thrust bearing and a radial bearing which are coaxial with the fourth member. Preferably, the electromechanical actuator further comprises a second electric motor which is capable of driving and rotating the fourth member. More preferably, the electromechanical actuator further comprises a rotation restriction mechanism for the first motion conversion mechanism. The rotation restriction mechanism for the first motion conversion mechanism is arranged to restrict the rotation of the first member.
[0010] Preferably, the rotation restriction mechanism for the second motion conversion mechanism comprises a braking mechanism which is capable of restricting rotation of the fourth member. More preferably, the braking mechanism of the rotation restriction mechanism for the second motion conversion mechanism comprises a torque limiter which is capable of restricting rotation of the fourth member when the torque acting on the fourth member is less than a value. predetermined. The torque limiter is configured to be able to change the predetermined value. More preferably, the torque limiter comprises two opposite elements, which are opposed to each other, and a pressure force adjusting member. The two opposing members are coupled to the fourth member and the pressure force adjusting member. The two opposing elements are configured to be coupled such that the transmission of force between the two opposed elements is permitted when the torque acting between the two opposed elements is less than a predetermined value. The two opposing elements are configured to freely rotate relative to each other when the torque acting between the two opposed elements is greater than or equal to the predetermined value. The pressure force adjusting member is configured to be able to adjust a thrust load acting between the two opposing members. More preferably, the electromechanical actuator further comprises a spring member located between one of the two opposed members and the pressure force adjusting member. The pressure force adjusting member is configured to be able to adjust a pressing force that presses the spring member against the opposite member. Preferably, the pressure force adjusting member comprises a solenoid. Preferably, the rotation restriction mechanism for the second motion conversion mechanism further comprises a torque limiter of a second motion conversion mechanism which is located between the first electric motor and the fourth member. The second motion conversion mechanism torque limiter includes two opposing second elements that are capable of transmitting a force to the first electric motor and the fourth element. The second and second opposing elements are configured to be coupled such that the transmission of force between the two opposing second elements is permitted when the torque acting between the first electric motor and the fourth element is less than a predetermined value. The two opposite second elements are configured to freely rotate relative to each other when the torque acting between the first electric motor and the fourth element is greater than or equal to the predetermined value. More preferably, the electromechanical actuator further comprises a torque limiter of first motion conversion mechanism located between the first electric motor and the first member. The torque limiter of a first motion conversion mechanism comprises two first opposed elements, one of which is coupled to the first electric motor and the other of which is coupled to the first element. The first two opposing members are configured to be coupled such that force transmission between the first opposing members is permitted when the torque acting between the first electric motor and the first member is less than a predetermined value. The first two opposing elements are configured to freely rotate relative to each other when the torque acting between the first electric motor and the first element is greater than or equal to the predetermined value.
[0011] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The invention, as well as its objects and advantages, may be better understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: FIG. 1 is a schematic diagram showing electromechanical actuators according to a first embodiment of the present invention which are each coupled to a flight control surface of an aircraft; FIG. 2 is a schematic diagram showing a state in which one of the flight control surfaces has been driven from the state shown in FIG. 1 by one of the corresponding electromechanical actuators; FIG. 3 is a schematic diagram partially in cross section showing one of the electromechanical actuators; FIG. 4 is a diagram illustrating the normal operation of the electromechanical actuator when a first electric motor is driven; FIG. 5 is a diagram illustrating the normal operation of the electromechanical actuator when a second electric motor is driven; FIG. 6 is a diagram illustrating the normal operation of the electromechanical actuator during a speed summation operation; FIG. 7 is a diagram illustrating the operation of the electromechanical actuator when a first motion conversion mechanism is jammed. FIG. 8 is a diagram illustrating the operation of the electromechanical actuator when a second motion conversion mechanism is jammed; FIG. 9 is a schematic side view partially in section of an electromechanical actuator according to a second embodiment of the present invention; FIG. 10 is a schematic side view partially in section of an electromechanical actuator according to a third embodiment of the present invention; the Pig. 11 is a diagram illustrating a speed summation operation of the third embodiment; FIG. 12 is a diagram illustrating the operation of the electromechanical actuator of the third embodiment when the first motion conversion mechanism is stuck (when the first electric motor is driven); FIG. 13 is a diagram illustrating the operation of the electromechanical actuator of the third embodiment when the second motion conversion mechanism is stuck (when the first electric motor is driven); FIG. 14 is a schematic side view partially in section of an electromechanical actuator according to a fourth embodiment of the present invention; FIG. 15 is a diagram illustrating the normal operation of the electromechanical actuator of the fourth embodiment when the first electric motor is driven; FIG. 16 is a diagram illustrating the operation of the electromechanical actuator of the fourth embodiment when the first motion conversion mechanism is jammed; FIG. 17 is a diagram illustrating the operation of the electromechanical actuator of the fourth embodiment when the second motion conversion mechanism is jammed; FIG. 18 is a schematic side view partially in section of an electromechanical actuator according to a fifth embodiment of the present invention; FIG. 19 is a diagram showing an electromechanical actuator according to a modified example when a ball screw mechanism is used as a motion conversion mechanism; and FIG. 20 is a diagram showing an electromechanical actuator according to another modified example when a roller screw mechanism is used as a motion conversion mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described with reference to the drawings. The following embodiments each describe an example in which an electromechanical actuator is arranged in a flight control surface drive mechanism, which drives a flight control surface of an aircraft. However, the present invention is not limited to the aspects illustrated in the following embodiments and can therefore be applied broadly. More specifically, the present invention can be broadly applied to an electromechanical actuator that includes a motion conversion mechanism and converts a rotational driving force, which is outputted by an electric motor, into a driving force. linear to output the linear drive force. First Embodiment FIG. 1 is a schematic diagram showing electromechanical actuators 1 according to a first embodiment of the present invention which are each coupled to a flight control surface 102 or 103 of an aircraft. Fig. 1 does not represent the main components of the aircraft. Fig. 1 schematically represents a portion of a wing 101, the flight control surface 102, and the flight control surface 103. In the present embodiment, the wing 101 is configured as a main wing of the aircraft. The flight control surface 102 is configured as a spoiler. The flight control surface 103 is configured, for example, as a fin. Each of the flight control surfaces 102, 103 is driven by one of the electromechanical actuators 1. Each electromechanical actuator 1 can be used to drive a rudder or elevator of the tail unit. Fig. 1 shows a rear end portion of the wing 101 as viewed in a lateral direction of the aircraft. In addition, FIG. 1 represents only schematic contours of wing 101 and flight control surfaces 102, 103.
[0012] Flying Control Surface Drive Mechanism In order to describe the electromechanical actuators 1, aircraft flight control surface drive mechanisms 100, to each of which one of the electromechanical actuators 1 is applied, will be described now. As shown in FIG. 1, the flight control surface drive mechanisms 100 are arranged in the wing 101 of the aircraft. The flight control surface drive mechanisms 100 are used to drive the flight control surfaces 102, 103 of the aircraft. Each flight control surface drive mechanism 100 comprises a rotation shaft (not shown), a pivot shaft 105, and one of the electromechanical actuators 1.
[0013] The rotation shafts are arranged in the wing 101. Each electromechanical actuator 1 comprises a housing 2, which is rotatably coupled to one of the rotation shafts. The electromechanical actuators 1 are thus supported by the wing 101 so as to be able to pivot about the respective rotation shafts. The pivot shafts 105 are each disposed in one of the flight control surfaces 102, 103. Each electromechanical actuator 1 includes an exit portion 12, one end of which is rotatably coupled to one of the flight control surfaces. 102, 103 corresponding. The flight control surfaces 102, 103 are each rotatably supported by a pivot shaft 106. The flight control surfaces 102, 103 are thus supported by the wing 101 so as to be pivotable about the respective pivot shafts 106. . In each electromechanical actuator 1, the outlet portion 12 protrudes from the housing 2 and is movable relative to the housing 2. More specifically, the outlet portion 12 is configured to be able to extend and retract relative to the housing 2. The configuration of the electromechanical actuator 1 for the flight control surface 102 is the same as that for the flight control surface 103. The configuration of the electromechanical actuator 1 for the flight control surface 102 will therefore be described below, and the explanation of the electromechanical actuator 1 for the flight control surface 103 is omitted.
[0014] Fig. 2 is a schematic diagram showing a state in which the flight control surface 102 has been driven from the state shown in FIG. 1 by the electromechanical actuator 1 of one of the flight control surface drive mechanisms 100. FIG. 1 shows a state of when the outlet portion 12 is retracted to the maximum in the housing 2. On the other hand, FIG. 2 shows a state of when the exit portion 12 is extended and projected from the housing 2. As shown in FIGS. 1 and 2, the operation of the electromechanical actuators 1 drives the flight control surface 102. The flight control surface 102 is driven to pivot about the pivot shaft 106 relative to the wing 101.
[0015] The flight control surface drive mechanism 100 shown in FIG. 1 may further comprise a reaction link. When an output of the electromechanical actuator 1 is transmitted to the flight control surface 102, the output can generate a reaction force from the flight control surface 102. In this case, the reaction link supports the force. of reaction. The reaction link has one end coupled to the rotation shaft (not shown) and the other end coupled to the pivot shaft 106. The arrangement of the reaction link prevents a load acting on the control surface of the 102, which is movable, directly affect the wing 101, which is fixed. Configuration of the Electromechanical Actuator FIG. 3 is a schematic partially cross-sectional diagram showing the electromechanical actuator 1. As described above, the electromechanical actuator 1 is configured as an actuator which drives the flight control surface 102. FIG. 3 does not represent the flight control surface 102 and the pivot shaft 105.
[0016] Referring to FIG. 3, the electromechanical actuator 1 comprises the housing 2, a first electric motor 3, a first braking mechanism 4, a first force transmission mechanism 5, a first motion conversion mechanism 6, a rotation stop mechanism 7, a second motion conversion mechanism 8, a second force transmission mechanism 9, a second electric motor 10, and a second braking mechanism 11. The first electric motor 3, the first braking mechanism 4, the second motor electrical 10, and the second braking mechanism 11 operate when they are driven by a controller (not shown).
[0017] For the sake of brevity, in each drawing, the direction of an arrow indicated by "before" refers to a front or forward side. The direction of an arrow indicated by "backward" refers to a backward or a backward side. Housing 2 is a hollow member which is a combination of three components in the present embodiment. More specifically, the housing 2 comprises a first housing portion 21, a second housing portion 22, and a cover 23. The first housing portion 21 has a tubular shape. The first housing portion 21 includes a groove 24 in a forward portion of the inner circumference. The groove 24 is annular and its center is on a central axis Si, which will be described later. The first housing portion 21 includes a rear end 21a opening towards the rear. The rear end 21a is coupled to the second housing portion 22. The second housing portion 22 serves as a basal housing portion formed separately from the first housing portion 21. The cover 23 covers the first housing portion 21. The cover 23 is shaped so that the cover 23 seals an opening which is formed in a lower portion of the first housing portion 21 and located at the rear end side. When the first housing portion 21, the second housing portion 22 and the cover 23 are combined to form the housing 2, the housing 2 comprises a housing body 25, a first projection 26, and a second projection 27. The housing housing 25 is tubular and accommodates the first motion conversion mechanism 6 and the second motion conversion mechanism 8. When accommodated in the housing body 25, the first motion conversion mechanism 6 and the second motion conversion mechanism movement 8 are arranged around the central axis Si. The central axis Si of the present embodiment extends in the front-to-back direction. The groove 24 of the housing 2 is formed in the housing body 25. The first projection 26 projects from a rear portion of the housing body 25. The first projection 26 is a hollow portion extending from the housing body 25 in a direction orthogonal to the central axis Si (or in the radial direction). The first projection 26 accommodates a distal portion of an output shaft 3b (described later) of the first electric motor 3 and the first force transmission mechanism 5. The second projection 27 is arranged at a location separated from the first projection 26 in the front-to-back direction. The second projection 27 is a hollow portion extending from the housing body 25 in a direction orthogonal to the central axis Si. The second projection 27 accommodates a distal portion of an output shaft 10b (described later) of the second electric motor 10 and the second force transmission mechanism 9. In the present embodiment, the first projection 26 protrudes upwardly from the housing body 25, and the second projection 27 projects downwardly from the housing. housing body 25. The first electric motor 3 is coupled to the first projection 26.
[0018] The first electric motor 3 is arranged to move the output portion 12 in the front-rear direction. The first electric motor 3 is, for example, a brushless motor, and is controlled, for example, using a pulse width modulation (PWM). The first electric motor 3 comprises a motor housing 3a and the output shaft 3b. The motor housing 3a is tubular and accommodates a rotor and a stator (not shown). The motor housing 3a is attached to the first projection 26. The motor housing 3a supports the output shaft 3b. The output shaft 3b protrudes from the rear of the motor housing 3a into the first projection 26 of the housing 2. The output shaft 3b is configured to be braked by the first braking mechanism 4. The first mechanism 4 is an example of a "rotation restriction mechanism for the first motion conversion mechanism" of the present invention. The first braking mechanism 4 is arranged to restrict the rotation of a first element 29 (first shaft 28), which will be described later. The first braking mechanism 4 is, for example, an electromagnetic clutch device. The first braking mechanism 4 must only be configured to be able to restrict the rotation of the first element 29 (output shaft 3b). The first braking mechanism 4 is located, for example, at the front of the motor housing 3a, and is supported by the motor housing 3a.
[0019] The output of the first electric motor 3 is transmitted to the first motion conversion mechanism 6 via the first force transmission mechanism 5. The first force transmission mechanism 5 is, for example, a gear reducer mechanism. In the present embodiment, the output (torque) of the first electric motor 3 is amplified through the first force transmission mechanism 5 and transmitted to the first motion conversion mechanism 6.
[0020] The first force transmission mechanism 5 comprises four gears 5a, 5b, 5c, 5d. The gears 5a to 5d can rotate relative to the housing 2. The gear 5a is fixed to the output shaft 3b of the first electric motor 3 and is able to rotate integrally with the output shaft 3b. Gear 5a meshes with gear 5b. The gear 5b rotates in solidarity with the gear 5c. Gear 5c meshes with gear 5d. Gear 5d is a straight gear. The gear 5d is rotatably supported by a bearing 5e on a support shaft 5f. The support shaft 5f is fixed to the first projection 26. The gear 5d rotates upon receiving the output of the first electric motor 3. The rotation of the gear 5d is transmitted to a straight-toothed portion 32 (described above). away) from the first motion conversion mechanism 6. The first motion conversion mechanism 6 is arranged to function as a motion conversion mechanism which converts the rotary motion of the output shaft 3b of the first electric motor 3 into linear motion of the output portion 12. The first motion conversion mechanism 6 is arranged in a rearward portion of the housing body 25. The first motion conversion mechanism 6 comprises a first shaft 28, a first element 29 operating in a direction of rotation. as a first nut, a second shaft 30, and a second member 31 operating as a first screw which is attached to the first member 29. In the present embodiment the first element 29 functions as an input-side element which is rotated by the output of the first electric motor 3. The second element 31 is integrally arranged with the output part 12. The second element 31 functions as an element of the output side which moves in an axial direction X1 (direction in which the central axis Si extends) relative to the first member 29 in accordance with the rotational force of the first member 29. The first member 29 is formed in an inner circumference of the first shaft 28. The first shaft 28 is a hollow cylindrical component. The first shaft 28 is located in the housing body 25. The axis of the first shaft 28 is aligned with the central axis Si. The straight gear portion 32 (fluted teeth) is formed on a rear portion of the outer circumference of the first tree 28.
[0021] The straight gear portion 32 is an example of "teeth configured to integrally rotate with the first member (first nut member)" of the present invention. The straight gear portion 32 includes fluted teeth formed around the outer circumference of the first shaft 28. In other words, the straight gear portion 32 includes a plurality of straight gears (fluted teeth) extending parallel in the axial direction. X1. The straight gear portion 32 meshes with the gear 5d of the first force transmission mechanism 5. This structure allows the first shaft 28 to move relative to the housing 2 in the axial direction X1 while keeping the geared portion. straight 32 meshing with gear 5d. Instead of such a structure in which the straight-toothed portion 32 forms grooves on the first shaft 28, a linear guide may be arranged on the first shaft 28. In this case, a gear is also arranged so that the The gear is configured to be able to rotate integrally with the first shaft 28 and to move in the axial direction X1 with respect to the first shaft 28 using the linear guide. The first member 29 is formed on a rear portion of the inner circumference of the first shaft 28. The first member 29 and the second member 31 are each a screw or a nut. More specifically, in the present embodiment, the first member 29 and the second member 31 are configured to be in direct contact with each other. The first member 29 includes a female thread. The first element 29 surrounds the second element 31. The second element 31 comprises a male thread. The second member 31 is attached to the first member 29 and moves linearly when the first member 29 is rotated. At least a portion of the second member 31 is inserted into an interior space of the first member 29. The second member 31 is formed on the second shaft 30. The second shaft 30 is a round rod-shaped member. The second shaft 30 is located in the housing body 25 of the housing 2. The axis of the second shaft 30 is aligned with the central axis Si. The second shaft 30 is inserted into the first shaft 28. The second shaft 30 is extends through a rear end of the housing 2 and is rotatably supported by the rear end of the housing 2. The outlet portion 12 is formed on a rear portion of the second shaft 30. More specifically, the second member 31 is formed in one piece with the output portion 12. The rotation stop mechanism 7 is coupled to the second shaft 30. The rotation stop mechanism 7 restricts the rotation of the second shaft 30 (second member 31) around the central axis Si. The rotational stop mechanism 7 comprises two links 7a, 7b. The link 7a is a rod-shaped element. One end of the link 7a is coupled to the first projection 26 of the housing 2 by a connecting shaft and is rotatable relative to the first projection 26. The other end of the link 7a is coupled to one end of the link 7b by a connecting shaft and is rotatable relative to the end of the link 7b. The link 7b is a rod-shaped element. The other end of the link 7b is coupled to the output portion 12 of the second shaft 30 by a connecting shaft and is rotatable relative to the output portion 12. In the above structure, the mechanism of rotation stop 7 restricts the rotation of the second shaft 30 while allowing the second shaft 30 to move in the axial direction X1. The rotation stop mechanism 7 may be replaced by a different rotation stop mechanism, including a rotation stop mechanism comprising a key or flutes. The second member 31 is formed, for example, on a front portion of the outer circumference of the second shaft 30. The male thread of the second member 31 is helically formed and is secured (threadedly coupled) to the first member 29. The first element 29 and second element 31 are coupled to each other so that a normal operation and a reverse operation can be performed. The normal operation refers to the axial displacement of the second member 31 when the first member 29 is rotating. The reverse operation refers to the rotation of the first member 29 as the second member 31 moves axially. In the above structure, when the first electric motor 3 is driven, the first member 29 is rotated. The rotation of the first element 29 is transmitted to the second element 31. This moves the second element 31 (second shaft 30) in the axial direction X1. The first motion conversion mechanism 6 and the second motion conversion mechanism 8 are arranged in a straight line.
[0022] When the first motion conversion mechanism 6 is operating normally, the second motion conversion mechanism 8 allows the first electric motor 3 to move the output portion 12 (second shaft 30) in the axial direction. When an abnormality, such as jamming, occurs in the first motion conversion mechanism 6, the second motion conversion mechanism 8 allows a force from outside the electromechanical actuator 1 (external force) to move. the outlet portion 12 in the axial direction. The second motion conversion mechanism 8 comprises the first shaft 28, a third member 33 functioning as a second screw formed in the first shaft 28, a third shaft 34, and a fourth member 35 operating as a second nut formed in the third shaft 34. More specifically, the first motion conversion mechanism 6 and the second motion conversion mechanism 8 share the first shaft 28. The first motion conversion mechanism 6 and the second motion conversion mechanism 8 have the same threading direction. In the present embodiment, the first motion conversion mechanism 6 and the second motion conversion mechanism 8 have a right-hand thread. The third element 33 and the fourth element 35 are each a screw or a nut. More specifically, in the present embodiment, the third member 33 and the fourth member 35 are configured to be in direct contact with each other. The third element 33 and the first element 29 are arranged in a straight line and are movable integrally with each other. The third member 33 is formed on a front portion of the outer circumference of the first shaft 28. The third member 33 includes a male thread. The male thread of the third member 33 is a groove formed helically. The third member 33 is surrounded by the fourth member 35. The fourth member 35 is formed in the third shaft 34. The third shaft 34 is a tubular component. The third shaft 34 is located in the housing body 25 of the housing 2. The axis of the third shaft 34 is aligned with the central axis Si. The third shaft 34 surrounds the first shaft 28. The fourth element 35 is arranged in a inner circumference of the third shaft 34. The third shaft 34 is received in the groove 24 of the housing body 25. The third shaft 34 is supported by a bearing unit 36. The bearing unit 36, which is held by the housing 2 and is coaxial with the fourth member 35, supports the third shaft 34 (fourth member 35). The bearing unit 36 comprises two thrust bearings 37 and two radial bearings 38. Each thrust bearing 37 is configured to receive a thrust load acting in the axial direction X1. Each thrust bearing 37 is held in the groove 24 of the housing body 25. The third shaft 34 is supported by the two thrust bearings 37 on two opposite side surfaces 24a of the groove 24. The third shaft 34 is also supported, in the groove 24, by the two radial bearings 38, each of which is located near one of the two thrust bearings 37. Each radial bearing 38 receives a radial load from the third shaft 34. Each thrust bearing 37 can be replaced by a bearing capable of supporting a thrust load and a radial load (for example, an oblique bearing).
[0023] The above structure restricts the movement of the third shaft 34 in the axial direction X1 with respect to the housing body 25. In addition, the third shaft 34 is supported by the housing body 25 and is able to rotate about the axis The fourth member 35 is formed in the inner circumference of the third shaft 34. The fourth member 35 is attached to the third member 33.
[0024] The fourth element 35 comprises a female thread. The female thread of the fourth member 35 is helical and meshes with the third member 33. The third member 33 and the fourth member 35 are coupled with each other so that a normal operation and a reverse operation can be performed. to be carried out. The normal operation refers to the axial displacement of the third member 33 as the fourth member is rotated. The reverse operation refers to the rotation of the fourth member 35 as the third member 33 moves axially. The second motion conversion mechanism 8 is coupled to the second electric motor 10 through the second force transmission mechanism 9. The second electric motor 10 is configured to provide the rotational (output) driving force to the fourth element 35 of the second motion conversion mechanism 8 during a speed summation operation, which will be described later. The second electric motor 10 is, for example, a brushless motor similar to that of the first electric motor 3. The second electric motor 10 is controlled, for example, using pulse width modulation (PWM). The second electric motor 10 comprises a motor housing 10a and an output shaft 10b.
[0025] The motor housing 10a is tubular and accommodates a rotor and a stator (not shown). The motor housing 10a is attached to the cover 23. The motor housing 10a supports the output shaft 10b. The output shaft 10b protrudes from the front of the motor housing 10a into the second projection 27 of the housing 2. The output shaft 10b is configured to be braked by the second braking mechanism 11.
[0026] The second braking mechanism 11 is an example of a "rotation restriction mechanism for second motion conversion mechanism" of the present invention. The second braking mechanism 11 is configured to selectively perform an operation which restricts the rotation of the fourth member 35 as the third member 33 moves linearly, and an operation which allows rotation of the fourth member 35 when the third member 33 moves in a linear fashion. The second braking mechanism 11 is, for example, an electromagnetic clutch device. The second braking mechanism 11 must only be configured to be able to restrict the rotation of the output shaft 10b. The second braking mechanism 11 is located, for example, at the rear of the motor housing 10a, and is supported by the motor housing 10a. The output of the second electric motor 10 is transmitted to the second motion conversion mechanism 8 via the second force transmission mechanism 9. The second force transmission mechanism 9 is, for example, a gear reducer mechanism. In the present embodiment, the output (torque) of the second electric motor 10 is amplified through the second force transmission mechanism 9 and is transmitted to the second motion conversion mechanism 8. The second force transmission mechanism 9 comprises four gears 9a, 9b, 9c, 9d. The gears 9a to 9d are rotatable relative to the housing 2. The gear 9a is attached to the output shaft 10b of the second electric motor 10 and is able to rotate integrally with the output shaft 10b. Gear 9a meshes with gear 9b. The gear 9b rotates in solidarity with the gear 9c. The gear 9c meshes with the gear 9d. The gear 9d is a straight gear.
[0027] The gear 9d is rotatably supported by a bearing 9e on a support shaft 9f. The support shaft 9f is attached to the second projection 27. The rotation of the gear 5d is transmitted to the teeth 34b, which are formed on the outer circumference of the third shaft 34. In the above structure, the output of the second electric motor 10 or the braking force generated by the second braking mechanism 11 is transmitted to the third shaft 34. The schematic structure of the electromechanical actuator 1 has been described. The operation of the electromechanical actuator 1 will now be described. More specifically, (1) normal operation using the first electric motor 3, (2) normal operation using the second electric motor 10, (3) a speed summation operation, (4) operation when the first conversion mechanism movement 6 is jammed, and (5) operation when the second motion conversion mechanism 8 is jammed will be described. (1) Normal Operation Using the First Electric Motor FIG. 4 is a diagram illustrating the normal operation of the electromechanical actuator 1 when the first electric motor 3 is driven. In the following description, arrows indicate examples of directions in which the components of the electromechanical actuator 1 move. Referring to FIG. 4, during normal operation using the first electric motor 3, the first motion conversion mechanism 6 operates in a state in which the third shaft 34 of the second motion conversion mechanism 8 is locked. This moves the output portion 12 in the axial direction X1. More specifically, the controller locks the output shaft 10b of the second electric motor 10 using the second braking mechanism 11. The output shaft 10b of the second electric motor 10 can not rotate. This locks the second force transmission mechanism 9, which is coupled to the second electric motor 10, and the third shaft 34. In other words, the rotation of the third shaft 34 is restricted. In this situation, when the first electric motor 3 is in operation, the rotation (indicated for example by the arrow D11 in Fig. 4) of the output shaft 3b of the first electric motor 3 is transmitted to the first shaft 28 by the 5. An example of a direction in which the first force transmitting mechanism rotates is indicated by the arrow D12 in FIG. 4. Accordingly, the first shaft 28 rotates about the central axis Si in the direction indicated by the arrow D13 in FIG. 4. When the first shaft 28 is rotated, the rotation of the first member 29 is converted into linear motion of the second member 31. This moves the outlet portion 12, which is formed integrally with the second member 31, into the axial direction X1 (direction indicated by the arrow D14 in Fig. 4). In this case, the rotation of the fourth element 35 (third shaft 34) is restricted. When the first shaft 28 rotates, the third element 33 is rotated relative to the fourth element 35 (third shaft 34) and moves in the axial direction X1. More specifically, the output portion 12 moves in the axial direction X1 of the total amount of the axial displacement of the output portion 12 when the first member 29 of the first motion conversion mechanism 6 is rotated relative to the second member 31 and axial displacement of the first shaft 28 when the third member 33 of the second motion conversion mechanism 8 is rotated relative to the fourth member 35. (2) Normal operation using the Second Electric Motor FIG. 5 is a diagram illustrating the normal operation of the electromechanical actuator 1 when the second electric motor 10 is driven. Referring to FIG. 5, during normal operation using the second electric motor 10, the second motion conversion mechanism 8 operates in a state in which the rotation of the first shaft 28 is restricted while the first shaft 28 can move in the axial direction X1. This moves the output portion 12 in the axial direction X1. More specifically, the controller locks the output shaft 3b of the first electric motor 3 by using the first braking mechanism 4. The output shaft 3b of the first electric motor 3 can not rotate. This locks the first force transmission mechanism 5, which is coupled to the first electric motor 3. In other words, the rotation of the first shaft 28 is restricted. However, since the straight gear portion 32 of the first shaft 28 includes straight gears extending in the axial direction X1, the first shaft 28 is movable relative to the gear 5d in the axial direction X1. In this situation, when the second electric motor 10 is in operation, the rotation (indicated for example by the arrow D21 in Fig. 5) of the output shaft 10b of the second electric motor 10 is transmitted to the third shaft 34 by the An example of a direction in which the second force transmitting mechanism 9 rotates is indicated by the arrow D22 in FIG. 5. This rotates the third shaft 34 about the central axis If, for example, as shown by the arrow D23 in FIG. 5.
[0028] When the third shaft 34 is rotated, the rotational movement of the fourth member 35 is converted into linear motion of the third member 33. This moves the first shaft 28, which is integrally formed with the third member 33, as well as the second shaft 30 (output portion 12) in the axial direction X1 (direction indicated by arrow D24 in Fig. 5). (3) Speed Summation Operation As shown in FIG. 6, during the summing operation performed by the first electric motor 3 and the second electric motor 10, the first motion conversion mechanism 6 and the second motion conversion mechanism 8 are driven to move the output portion 12 into the axial direction X1 (direction indicated by the arrow D14, D24 in Fig. 6). In this case, the operation of the output portion 12 is a combination (1) of the operation of the output portion 12 when the first electric motor 3 is driven and (2) the operation of the output portion 12 when the second motor electrical 10 is driven, which have been described above. Arrows D11, D12, D13, D21, D22, D23 shown in FIG. 6 show examples of directions in which the components of the electromechanical actuator 1 rotate during this operation. (4) Operation when the First Movement Conversion Mechanism is Stuck FIG. 7 is a diagram illustrating the operation of the electromechanical actuator 1 when the first motion conversion mechanism 6 is jammed. Referring to FIG. 7, when the first motion conversion mechanism 6 is jammed, the second brake mechanism 11 unlocks the third shaft 34. This allows a force applied from outside the electromechanical actuator 1 to move the output portion 12 into the axial direction X1. More specifically, jamming may occur in the first motion conversion mechanism 6, for example, when a foreign material is taken between the first member 29 and the second member 31 (the jammed location is indicated by the symbol J1 on the Fig. 7). This disables the relative movement of the first and second members 29, 31. Accordingly, the axial movement of the output portion 12 is disabled. In this case, the controller cancels the braking action of the second fretting mechanism 11. This cancels the rotation restrictions of the output shaft 10b of the second electric motor 10, the gears 9a to 9d of the second gear transmission mechanism. force 9, and the third shaft 34 (fourth element 35). In this situation, when the output portion 12 moves in the axial direction X1 upon receipt of the force from the flight control surface 102, the second shaft 30 moves in solidarity with the first shaft 28 in the Axial direction X1. In this case, the fourth element 35 of the third shaft 34 can rotate around the central axis Si. When the third element 33 of the first shaft 28 moves in the axial direction X1, the fourth element 35 of the third shaft 34 is therefore in position. rotation about the central axis Si and allows the axial movement of the output part 12. This allows the output part 12 to move in the axial direction X1 (for example, the direction indicated by the arrow D41 on the Fig. 7) including in case of jamming. At this time, the controller can restrict the rotation of the output shaft 3b by using the first braking mechanism 4. In this case, the rotations of the output shaft 3b, the gears 5a to 5d, and the first shaft 28 are restricted. This moves the first shaft 28 in the axial direction X1 more assuredly. Alternatively, one of the first electric motor 3 and the second electric motor 10 may be driven to move the output portion 12 in the axial direction X1. Examples of directions in which the third shaft 34, the gears 9a to 9d of the second force transmission mechanism 9 and the output shaft 10b of the second electric motor 10 rotate are indicated by the arrows D42, D43, D44 in FIG. . 7. (5) Operation When Second Movement Conversion Mechanism Is Stuck FIG. 8 is a diagram illustrating the operation of the electromechanical actuator 1 when the second motion conversion mechanism 8 is jammed. Referring to FIG. 8, when the second motion conversion mechanism 8 is jammed, the second brake mechanism 11 unlocks the third shaft 34. This allows a force applied from outside the electromechanical actuator 1 to move the output portion 12 into the axial direction X1.
[0029] More specifically, jamming may occur in the second motion conversion mechanism 8, for example, when a foreign material is caught between the third member 33 and the fourth member 35 (the jammed location is indicated by the symbol J2 on the Fig. 8). This disables the relative movement of the third and fourth members 33, 35. As a result, the axial movement of the output portion 12 is disabled. In this case, the controller cancels the braking action of the second braking mechanism 11. This cancels the rotation restrictions of the output shaft 3b of the first electric motor 3, the gears 5a to 5d of the first force transmission mechanism 5, and the third shaft 34 (fourth element 35). Accordingly, upon receiving the force from the flight control surface 102, the output portion 12 can be moved in the axial direction X1. The displacement of the outlet portion 12 in the axial direction X1 rotates the first shaft 28 relative to the second shaft 30. At this time, the third member 33 and the fourth member 35 of the third shaft 34 rotate integrally around the central axis Si. This allows the output part 12 to move in the axial direction X1 (for example, the direction indicated by the arrow D41 in Fig. 8) including in case of jamming. Examples of directions in which the third shaft 34, the gears 9a to 9d of the second force transmission mechanism 9, and the output shaft 10b of the second electric motor 10 rotate are indicated by the arrows D42, D43, D44 on the Fig. 8.
[0030] As described above, in the electromechanical actuator 1 of the present embodiment, during normal operation, in which the first motion conversion mechanism 6 is not jammed, the controller restricts the rotation of the fourth element 35 to the In this situation, when the first electric motor 3 is driven, the output of the first electric motor 3 is transmitted to the second element 31 from the first element 29. This results in the linear movement of the first motor 31. second element 31 (output part 12). When the jamming of the first motion conversion mechanism 6 locks the first member 29 and the second member 31, the second braking mechanism 11 operates to allow the fourth member 35 to rotate as the third member 33 moves. More specifically, the controller cancels the braking action of the second braking mechanism 11. This allows rotation of the fourth member 35 when the third member 33 moves axially. In this case, when the second member 31 moves linearly upon receipt of an external force, the first member 29 also moves linearly. In other words, the third element 33 also moves linearly. In this case, the fourth member 35 rotates as the third member 33 moves linearly. The fourth element 35 thus allows the linear movement of the third element 33. In other words, the electromechanical actuator 1 can move the output part 12 (for example, an actuating part, such as a rod), which is coupled to the second element 31, in a more assured way even in case of jamming. In addition, the second braking mechanism 11 only needs to perform an easy operation, namely determining whether rotation of the fourth member 35 is allowed or not. This simplifies the structure of the second brake mechanism 11. In addition, there is no need to arrange heavy equipment, such as a number of electromagnetic clutches. This further reduces the weight of the electromechanical actuator 1. The electromechanical actuator 1 thus has a simple structure and allows the movement of the output portion 12 in a more secure manner including in case of jamming.
[0031] The electromechanical actuator 1 comprises the first to fourth members 29, 31, 33, 35, each of which is a screw or a nut. This structure allows each of the motion conversion mechanisms 6, 8 to be formed using an inexpensive configuration. The electromechanical actuator 1 comprises the straight-toothed portion 32 which forms grooves extending in the axial direction X1 on the outer circumference of the first shaft 28. In this structure, when the first motion conversion mechanism 6 is jammed, the first shaft 28 (first element 29 and third 33 element) can move in the axial direction X1 while the straight-toothed portion 32 is held in mesh with gear 5d, which receives the output of the first electric motor 3. The actuator electromechanical 1 comprises the rotation stop mechanism 7 which restricts the rotation of the second element 31. This structure ensures the axial movement of the second element 31 when the first element 29 is rotating. In other words, the second element 31 can be prevented from rotating along the first element 29. In the electromechanical actuator 1, the first shaft 28 comprises the first element 29 and the third element 33, which are arranged in a straight line. The electromechanical actuator 1 can therefore be elongated in the axial direction X1. This limits the expansion of the electromechanical actuator 1 in the radial direction of the first shaft 28. Such a shape is particularly favorable for the electromechanical actuator 1 used for an aircraft, in which there is a strong demand for miniaturization in a radial direction . In the electromechanical actuator 1, the first shaft 28, the second shaft 30, and the third shaft 34 are coaxial with each other. This limits the expansion of the electromechanical actuator 1 in the radial direction of the first shaft 28 in a more assured manner. In the electromechanical actuator 1, when the rotation of the fourth element 35 is restricted as a function of the axial displacement of the third element 33, the fourth element 35 receives a relatively high axial force from the third element 33. Such axial force can be received Certainly by the thrust bearings 37, which support the fourth element 35. In the electromechanical actuator 1, when the rotation of the fourth element 35 is permitted, the second electric motor 10 can be driven to rotate the fourth element 35. In this situation, the gearing of the fourth member 35 with the third member 33 allows axial movement of the third member 33. As the third member 33 moves, the first member 29 and the second member 31 move in the axial direction X1. More specifically, the amount of axial displacement of the second element 31 is the total amount of axial displacement of the second element 31 driven by the first electric motor 3 and the axial displacement of the second element 31 driven by the second electric motor 10. Such an operation of Speed summation further increases the amount of axial displacement of the second member 31. This further rapidly moves the output portion 12, which is coupled to the second member 31. In other words, the electromechanical actuator 1 can increase a response rate. In the electromechanical actuator 1, even when the rotation of the first element 29 is restricted, the second electric motor 10 can be driven to move the second element 31 in the axial direction X1. More specifically, when the second electric motor 10 is driven to rotate the fourth member 35, the first braking mechanism 4 limits the rotation of the third member 33 along the fourth member 35. This further ensures axial movement of the third member 33 resulting from the relative rotation of the fourth element 35 and the third element 33, in other words, the axial movement of the first element 29 and the second element 31. In the electromechanical actuator 1, the second brake mechanism 11 only needs to restrict the This further simplifies the structure of the second braking mechanism 11. Second Embodiment FIG. 9 is a schematic side view partially in section of an electromechanical actuator 1A according to a second embodiment of the present invention. Here, the description will focus on the differences from the components of the first embodiment. In FIG. 9, the same reference symbols are given for the components which are the same as the corresponding components of the first embodiment. These components will not be described in detail. Referring to FIG. 9, the electromechanical actuator 1A corresponds to the electromechanical actuator 1 to the exclusion of the second electric motor 10. The second braking mechanism 11 comprises a braking shaft 11a which is coupled to the gear 9a and capable of rotating substantially. integral with the gear 9a. In this structure, the electromechanical actuator 1A can perform the same operations (1) of normal operation using the first electric motor 3, (4) of operation when the first motion conversion mechanism 6 is jammed, and (5) operating when the second motion conversion mechanism 8 is stuck, which have been described. In order to provide redundancy, a plurality of electromechanical actuators 1A may be arranged in a flight control surface 102. In this case, when one of the electromechanical actuators 1A is jammed, the controller cancels the braking operation of the second braking mechanism 11 of the electromechanical actuator 1A. This allows another electromechanical actuator 1A to drive the flight control surface 102. Third Embodiment FIG. 10 is a schematic side view partially in section of an electromechanical actuator 1B according to a third embodiment of the present invention. Referring to FIG. 10, the electromechanical actuator 1B differs from the electromechanical actuator 1 of the first embodiment in the following aspects. In one aspect, a housing 2B is used in place of the housing 2. In another aspect, a force distribution mechanism 40 is provided. The electromechanical actuator 1B comprises the housing 2B, the first electric motor 3, the first braking mechanism 4, the force distribution mechanism 40, the first motion conversion mechanism 6, the rotation stop mechanism 7, and the second motion conversion mechanism 8. The housing 2B is formed by a single element. The housing 2B comprises a housing body 25B and a force distribution mechanism receptacle 41. The housing body 25B is a tubular component and accommodates the first motion conversion mechanism 6 and the second motion conversion mechanism 8. The The force distribution mechanism receptacle 41 projects from an intermediate portion of the housing body 25B. The force distribution mechanism receptacle 41 is a hollow portion extending from the housing body 25B in the direction orthogonal to the central axis Si (radial direction). The force distribution mechanism receptacle 41 accommodates the force distribution mechanism 40 and a distal portion of the output shaft 3b of the first electric motor 3. The motor housing 3a of the first electric motor 3 is attached to the mechanism receptacle force distribution 41 and is located outside the force distribution mechanism receptacle 41. The first electric motor 3 is coupled to the first motion conversion mechanism 6 and the second motion conversion mechanism 8 via of the force distribution mechanism 40. The force distribution mechanism 40 divides the output of the first electric motor 3 and transmits the divided outputs to the first motion conversion mechanism 6 and the second motion conversion mechanism 8. The distribution mechanism 40 is configured to allow the axial movement of the outlet portion 12 even in case of jamming.
[0032] The force distribution mechanism 40 comprises a gear unit 42, a first torque limiter 43, and a second torque limiter 44. The gear unit 42 transmits the output of the first electric motor 3 to each of the limiters 42. torque 43, 44. The gear unit 42 is, for example, a parallel-axis gear mechanism, and includes two gears 45, 46. The gear 45 is attached to the output shaft 3b and s'. is engaged with the gear 46. The gear 46 is attached to a support shaft 47. The support shaft 47 is rotatably supported by a bearing 48 in the force distribution mechanism receptacle 41 of the housing 2B. The support shaft 47 supports the torque limiters 43, 44. When the torque acting between the first electric motor 3 and the first motion conversion mechanism 6 is greater than or equal to a predetermined value, the first torque limiter 43 turns freely. The first torque limiter 43 is located between the first electric motor 3 and the first element 29 of the first motion conversion mechanism 6. The first torque limiter 43 is an example of a torque limiter of a first conversion mechanism movement which restricts the rotation of the first screw of the present invention. The first torque limiter 43 comprises a spring seat 51, a spring 52, two opposed first members 53, 54, and balls 55. The spring seat 51 is a plate-shaped component attached to the support shaft 47 and located on the rear side of the gear 46. The spring seat 51 receives the spring 52. The spring 52 is, for example, a helical spring, and surrounds the support shaft 47. The spring 52 generates a spring force. soliciting that solicits the first opposing elements 53, 54 towards each other. The first opposed members 53, 54 are configured to be coupled so that a force can be transmitted from one to the other when the torque acting between the first electric motor 3 and the first member 29 is less than the predetermined value. The first opposing members 53, 54 are configured to freely rotate relative to each other when the torque acting between the first electric motor 3 and the first member 29 is greater than or equal to the predetermined value. The first opposing members 53, 54 are each disc-shaped and are supported by the support shaft 47. The first opposing member 53 is in contact with the spring 52 and is splinedly coupled to the support shaft 47. The first opposite element 53 is movable in the axial direction X1 and is able to rotate integrally with the support shaft 47. The first opposite element 53 is therefore capable of transmitting a force to the output shaft 3b of the first motor 3. The first opposing member 54 is supported by the support shaft 47 and is rotatable relative to the support shaft 47. The rearward movement of the first opposing member 54 is restricted by a stop (not shown). . The first opposing element 54 is coupled to the first element 29 via an intermediate gear 57 so that a force can be transmitted to the first element 29. The first opposing elements 53, 54 each comprise grooves in a surface opposite to the other element. The grooves are arranged in the circumferential direction of the support shaft 47. The balls 55 are located in the grooves. In the above structure, when the torque acting between the first two opposing members 53, 54 reaches or exceeds the predetermined value, the first opposing member 53 moves toward the gear 46 against the biasing force of the spring 52. The distance thus increases between the first opposed elements 53, 54. Then, the balls 55 roll between the first opposed elements 53, 54. This rotates the first opposed elements 53, 54 relative to each other. The first opposing member 54 includes teeth on the outer circumference. The teeth of the first opposing member 54 mesh with the intermediate gear 57. The intermediate gear 57 is arranged parallel to the straight gear portion 32 of the first shaft 28 and meshes with the straight gear portion 32. The intermediate gear 57 is rotatably supported in the force distribution mechanism receptacle 41 of the housing 2B by a support shaft and a bearing.
[0033] The first torque limiter 43 and the second torque limiter 44 are in a front-to-back symmetrical arrangement. When the torque acting between the first electric motor 3 and the second motion conversion mechanism 8 is greater than or equal to the predetermined value, the second torque limiter 44 rotates freely. The second torque limiter 44 is located between the first electric motor 3 and the fourth element 35. The second torque limiter 44 is an example of a "rotation restriction mechanism for a second motion conversion mechanism" and an example of a "limiter second motion conversion mechanism pair of the present invention.
[0034] The second torque limiter 44 comprises a spring seat 61, a spring 62, two second opposed members 63, 64, and balls 65. The spring seat 61 is a plate-shaped member attached to the support shaft 47. and located on the forward side of the gear 46. The spring seat 61 receives the spring 62. The spring 62 is, for example, a helical spring, and surrounds the support shaft 47. The spring 62 generates a biasing force which solicits the second opposing elements 63, 64 towards each other. The second opposing elements 63, 64 are configured to be coupled so that a force can be transmitted from one to the other when the torque acting between the first electric motor 3 and the fourth element 35 is less than the value. predetermined. The second opposing members 63, 64 are configured to freely rotate relative to each other when the torque acting between the first electric motor 3 and the fourth member 35 is greater than or equal to the predetermined value. The second opposing members 63, 64 are each disc-shaped and are supported by the support shaft 47. The second opposing member 63 is in contact with the spring 62 and is splinedly coupled to the support shaft 47. second opposite element 63 is movable in the axial direction X1 and is able to rotate integrally with the support shaft 47. The second opposite element 63 is therefore capable of transmitting a force to the output shaft 3b of the first electric motor 3. The second opposite member 64 is supported by the support shaft 47 and is rotatable relative to the support shaft 47. The forward movement of the second opposing member 64 is restricted by a stop (not shown). The second opposite member 64 is coupled to the fourth member 35 through an intermediate gear 67 so that a force can be transmitted to the fourth member 35. The second opposing members 63, 64 each include grooves in a surface opposite to the other element. The grooves are arranged in the circumferential direction of the support shaft 47. The balls 65 are located in the grooves. In the above structure, when the torque acting between the two opposite second members 63, 64 reaches or exceeds the predetermined value, the second opposite member 63 moves toward the gear 46 against the biasing force of the spring 62. The distance Therefore, the balls 65 roll between the second opposing members 63, 64. This rotates the second opposed members 63, 64 relative to each other. The second opposite member 64 includes teeth on the outer circumference. The teeth of the second opposite member 64 meshes with the intermediate gear 67. The intermediate gear 67 is arranged parallel to the teeth 34b of the third shaft 34 and meshes with the teeth 34b. The intermediate gear 67 is rotatably supported in the force distribution mechanism receptacle 41 of the housing 2B by a support shaft and a bearing. The schematic structure of the electromechanical actuator 1B has been described. The operation of the electromechanical actuator 1B will now be described. The electromechanical actuator 1B can perform (a) a speed summation operation (normal operation), (b) an operation when the first motion conversion mechanism 6 is stuck (when the first electric motor is driven), and (c ) operation when the second motion conversion mechanism 8 is stuck (when the first electric motor is driven). (a) Speed Summation Operation FIG. 11 is a diagram illustrating the speed summation operation of the third embodiment. Referring to FIG. 11, in the speed summation operation performed by the first electric motor 3 (normal operation), the first motion conversion mechanism 6 and the second motion conversion mechanism 8 are in operation. This moves the output portion 12 in the axial direction X1 (direction indicated by the arrow D55 in Fig. 11). More specifically, when the first electric motor 3 is driven, the rotation (indicated for example by the arrow D51 in Fig. 11) of the output shaft 3b of the first electric motor 3 is transmitted to the force distribution mechanism 40. In the force distribution mechanism 40, the gear 46 rotates, for example, in a direction indicated by the arrow D52 in FIG. 11. This rotates the support shaft 47 and the torque limiters 43, 44 in the same direction as the gear 46 (e.g., the direction indicated by the arrow D52 in Fig. 11). The rotations of the torque limiters 43, 44 are respectively transmitted to the first shaft 28 and the third shaft 34 through the respective intermediate gears 57, 67. The direction of rotation of the intermediate gear 57 and the direction of rotation of the intermediate gear 67 are, for example, indicated respectively by the arrow D53 and by the arrow D56 in FIG. 11. Accordingly, the first shaft 28 rotates about the central axis Si in the direction indicated by the arrow D54 in FIG. 11. In accordance with this rotation of the first shaft 28, the rotation of the first member 29 is converted into linear movement of the second member 31. This moves the outlet portion 12, which is integrally arranged with the second member 31, in the direction axial X1. The rotation of the intermediate gear 57 rotates the third shaft 34 about the central axis X1 as indicated by the arrow D57 in FIG. 11. In accordance with this rotation of the third shaft 34, the rotation of the fourth member 35 is converted into linear movement of the third member 33. This moves the first shaft 28, which is integrally arranged with the third member 33, as well as the output portion 12 in the axial direction X1. (b) Operation when the First Movement Conversion Mechanism is Stuck (when the First Electric Motor is Driven) FIG. 12 is a diagram illustrating the operation when the first motion conversion mechanism 6 is stuck (when the first electric motor is driven). Referring to FIG. 12, even when the first motion conversion mechanism 6 is jammed, the output portion 12 can be moved in the axial direction X1 when the first electric motor 3 is driven. More specifically, jamming can occur in the first motion conversion mechanism 6, for example, when a foreign material is taken between the first member 29 and the second member 31. The symbol J1 in FIG. 12 shows an example of a location wedged between the first and second members 29, 31. This prevents the axial movement of the exit portion 12 which is effected when the first and second members 29, 31 move relative to each other. the other. In this case, the rotation of the first shaft 28 is restricted. The intermediate gear 57 and the first opposite element 54 can not rotate.
[0035] In this situation, when the first electric motor 3 generates a torque that is greater than or equal to a predetermined value, the output shaft 3b rotates, for example, in a direction indicated by the arrow D71 in FIG. 12. This rotates the gear 46, the support shaft 47, and the two opposite second members 63, 64 in a direction indicated by the arrow D72 in FIG. 12. This rotation is transmitted to the third shaft 34 via the intermediate gear 67. The third shaft 34 (fourth member 35) rotates in a direction indicated by the arrow D73 in FIG. 12. Accordingly, the third member 33 (i.e., the first shaft 28) moves in the axial direction indicated by the arrow D74 in FIG. 12. In addition, the output portion 12 moves in the direction indicated by the arrow D74. In this case, the rotational torque of the support shaft 47 is greater than or equal to the predetermined value. Accordingly, when the support shaft 47 rotates the first opposing member 53, the force acting between the first opposed members 53, 54 exceeds the biasing force of the spring 52. The first opposing member 53 thus compresses the spring 52. This increases the distance between the first opposed members 53, 54. Then the balls 55 held between the first opposed members 53, 54 roll between the first opposing members 53, 54. The first opposing member 53 rotates freely relative to the first opposed member. 54. This allows the rotation of the support shaft 47 (rotation of the output shaft 3b of the first electric motor 3). In other words, the output portion 12 is movable in the axial direction X1 even in case of jamming. (c) Operation when the Second Movement Conversion Mechanism is Stuck (when the First Electric Motor is Driven) FIG. 13 is a diagram illustrating the operation when the second motion conversion mechanism 8 is stuck (when the first electric motor is driven). Referring to FIG. 13, even when the second motion conversion mechanism 8 is jammed, the output portion 12 can be moved in the axial direction X1 when the first electric motor 3 is driven.
[0036] More specifically, jamming may occur in the second motion conversion mechanism 8, for example, when a foreign material is taken between the third member 33 and the fourth member 35. The symbol J2 in FIG. 13 shows an example of a location wedged between the third and fourth members 33, 35. This disables the relative movement of the third and fourth members 33, 35. As a result, the axial movement of the output portion 12 is disabled. In this situation, when the first electric motor 3 generates a torque that is greater than or equal to a predetermined value, the output shaft 3b rotates, for example, in a direction of the arrow D81 in FIG. 13. This rotates the gear 46 and the first two opposed members 53, 54 in a direction indicated by the arrow D82 in FIG. 13. This rotation is transmitted to the first shaft 28 via the intermediate gear 57. The first shaft 28 (first member 29) rotates in a direction indicated by the arrow D83 in FIG. 13. Accordingly, the first member 29 (that is, the first shaft 28) moves in the axial direction indicated by the arrow D84. In addition, the output portion 12 moves in the direction indicated by the arrow D84 in FIG. 13. In this case, the force which is transmitted from the third shaft 34 through the intermediate gear 67 and which acts between the second opposing elements 63, 64 is greater than the biasing force of the spring 62. The second opposite element 63 thus compresses the spring 62. This increases the distance between the second opposing elements 63, 64. Then, the balls 65 held between the second opposite elements 63, 64 roll between the second opposite elements 63, 64. The second element opposite 63 rotates freely relative to the second opposite member 64. This allows the rotation of the third shaft 34 (rotation of the first shaft 28). In other words, the output portion 12 is movable in the axial direction X1 even in case of jamming. As described above, in the electromechanical actuator 1B, when the torque acting between the first electric motor 3 and the fourth element 35 is smaller than the predetermined value, the output of the first electric motor 3 is transmitted to the fourth element 35 by the intermediate of the second torque limiter 44. The rotation of the fourth member 35 moves the third member 33 in the axial direction X1. As a result, the second member 31 (output portion 12) moves in the axial direction X1. This completes the speed summation operation, which has been described. When the torque acting between the first electric motor 3 and the fourth element 35 is greater than or equal to the predetermined value, the fourth element 35 rotates freely with respect to the output shaft 3b of the first electric motor 3. This allows the rotation of the fourth element 35 when the third element 33 moves axially. In other words, when the first motion conversion mechanism 6 is jammed, the first element 29, the second element 31, and the third element 33 can move in the axial direction X1. In the electromechanical actuator 1B, when the first element 29 of the first motion conversion mechanism 6 displaces the second element 31 in the axial direction X1 using the output of the first electric motor 3, the first torque limiter 43 can transmit the output from the first electric motor 3 to the first member 29. However, when the first motion conversion mechanism 6 is jammed, the rotation of the first member 29 is restricted. As a result, the torque acting between the first electric motor 3 and the first element 29 reaches or exceeds the predetermined value. In this case, the first two opposing elements 53, 54 rotate freely with respect to each other. This avoids the locking of the output shaft 3b of the first electric motor 3, which allows a continuous rotation of the first electric motor 3. Consequently, the first electric motor 3 can rotate the fourth element 35 of the second conversion mechanism. of movement 8.
[0037] In other words, even when the first motion conversion mechanism 6 is jammed, the output portion 12 can be moved in the axial direction X1 using the first electric motor 3 and the second motion conversion mechanism 8. Fourth Embodiment Fig. 14 is a schematic side view partially in section of an electromechanical actuator 1C according to a fourth embodiment of the present invention. Referring to FIG. 14, instead of the second braking mechanism 11 of the electromechanical actuator 1A (see Fig. 9), the electromechanical actuator 1C comprises a second braking mechanism 11C. The electromechanical actuator 1C comprises a housing 2C, the first electric motor 3, the first braking mechanism 4, a first force transmission mechanism 5C, the first motion conversion mechanism 6, the rotation stop mechanism 7, the second motion conversion mechanism 8, a second force transmission mechanism 9C, and the second brake mechanism 11C. The housing 2C comprises a first housing portion 21C and a second housing portion 22C. The first housing portion 21C and the second housing portion 22C, which are arranged and coupled to each other in the front-to-back direction, form the housing 2C. The housing 2C comprises a housing body 25C, a first projection 26C, and a second projection 27C.
[0038] The housing body 25C is tubular and accommodates the first motion conversion mechanism 6 and the second motion conversion mechanism 8. The housing body 25C is annular and its center is on the central axis Si. The first projection 26C is protruding from a rear portion of the housing body 25C. The first protrusion 26C is a hollow portion extending from the housing body 25C in the direction orthogonal to the central axis Si (or in the radial direction). The first projection 26C accommodates the distal portion of the output shaft 3b of the first electric motor 3 and the first force transmission mechanism 5C. The second projection 27C is arranged at a location separate from that of the first projection 26C in the front-to-back direction. The second projection 27C is a hollow portion extending from the housing body 25C in a direction orthogonal to the central axis Si. The second projection 27C accommodates the second force transmission mechanism 9C and the second brake mechanism 11C. The first electric motor 3 is coupled to the first projection 26C. The first electric motor 3 is configured to be able to transmit a force to the first motion conversion mechanism 6 via the first force transmission mechanism 5C. The first force transmission mechanism 5C comprises two gears 201, 202. The gear 201 is fixed to the output shaft 3b of the first electric motor 3 and is movable integrally with the output shaft 3b. The gear 201 meshes with the gear 202. The gear 202 is rotatably supported by the first projection 26C of the housing 2C. The gear 202 meshes with the straight gear portion 32 of the first motion conversion mechanism 6. The gear 202 rotates upon receiving the output of the first electric motor 3. The rotation of the gear 202 is transmitted to the straight-toothed portion 32 of the first motion-conversion mechanism 6.
[0039] In the present embodiment, the third shaft 34, in which the second motion conversion mechanism 8 of the fourth member 35 is formed, is supported by a bearing unit 36C in the housing body 25C of the housing 2C. The bearing unit 36C is formed using, for example, a ball bearing. The bearing unit 36C is configured to be capable of receiving a thrust load and a radial load acting on the third shaft 34. This structure restricts the movement of the third shaft 34 relative to the housing body 25C in the axial direction X1. The third shaft 34 is supported by the housing body 25C and is rotatable about the central axis Si. The second motion conversion mechanism 8 is coupled to the second brake mechanism 11C via the second force transmission mechanism. 9C.
[0040] The second force transmission mechanism 9C comprises two gears 203, 204. The gear 203 meshes with the teeth 34b, which are formed on the outer circumference of the third shaft 34. The gear 203 is rotatably supported by the second gear. 27C housing projection 2C. The gear 203 meshes with the gear 204. The gear 204 is rotatably supported in the second projection 27C by a support shaft 205 and a bearing 206. The support shaft 205 is coupled to the gear 204 and is able to rotate integrally with the gear 204. The support shaft 205 is coupled to a torque limiter 200 of the second brake mechanism 11C. The second brake mechanism 11C includes the torque limiter 200. The torque limiter 200 is configured to restrict the rotation of the fourth member 35 when the torque acting on the fourth member 35 is less than a predetermined value. In other words, the torque limiter 200 turns freely when the torque 15 acting on each of the motion conversion mechanisms 6, 8 is greater than or equal to the predetermined value. The torque limiter 200 is configured to be able to change the predetermined value. The torque limiter 200 comprises two opposed opposing members 207, 208, balls 209, a spring member 210, and a pressure force adjusting member 211. The opposing members 207 , 208 are configured to be coupled to transmit the force from one to the other when the torque acting between the fourth member 35 and the pressure force adjusting member 211 is less than the predetermined value. In addition, the opposing members 207, 208 are configured to freely rotate relative to each other when the torque acting between the fourth member 35 and the pressure force adjusting member 211 is greater than or equal to the predetermined value. The opposing members 207, 208 are each disk-shaped and are supported by the support shaft 205. The opposing member 208 is attached to the support shaft 205 and can rotate solidly with the support shaft. 205. The opposite member 207 is mounted on the support shaft 205 and is rotatable relative to the support shaft 205. The opposite member 207 is urged by the spring member 210 toward the opposite member 208.
[0041] The spring member 210 is, for example, a coil spring. The spring member 210 is located between the pressure force adjusting member 211 and the opposing member 208. The pressure force adjusting member 211 is capable of adjusting the force pressing the spring member 210 into direction of the opposite member 207. The pressure force adjusting member 211 is, for example, a solenoid whose operation is controlled by the controller. The pressure force adjusting member 211 comprises a housing 211b, which is attached to the housing 2C. The pressure force adjusting member 211 comprises a rod 211a, which receives the spring member 210 and urges the spring member 210 toward the opposite member 207. The opposing members 207, 208 each comprise grooves in a surface opposite to the other element. The grooves are arranged in the circumferential direction of the support shaft 205. The balls 209 are located in the grooves. This structure couples the opposing elements 207, 208 to the fourth member 35 and the pressure force adjusting member 211. When the torque acting between the opposed members 207, 208 reaches or exceeds the predetermined value, the opposite member 207 becomes moves towards the spring member 210 against the biasing force of the spring member 210. The distance thus increases between the opposed members 207,208. Then the balls 209 roll between the opposed members 207,208. rotates the opposed elements 207, 208 relative to each other. The pressure force adjusting member 211 sets a torque value of the opposite member 207 when the opposing member 208 begins to rotate freely relative to the opposing member 207. The pressure force adjusting member 211 sets a thrust load, with which the opposite member 207 is pressed toward the opposite member 208. In the present embodiment, the pressure force adjusting member 211 is formed using the solenoid. The pressure force adjusting member 211 comprises the housing 211b and the rod 211a. The rod 211a protrudes from the housing 211b. The rod 211a is configured so that a protruding amount of the housing 211b can be modified by a drive source accommodated in the housing 211b, such as an electromagnet. The rod 211a applies a pressing force on the opposite element 207 in correspondence with the amount protruding from the housing 211b. The positions can be exchanged between the first electric motor 3 and the second brake mechanism 11C.
[0042] The schematic structure of the electromechanical actuator 1C has been described. The operation of the electromechanical actuator 1C will now be described. More specifically, (A) normal operation using the first electric motor 3, (B) operation when the first motion conversion mechanism 6 is stuck, and (C) operation when the second motion conversion mechanism 8 is stuck. will be described. (A) Normal Operation Using the First Electric Motor FIG. 15 is a diagram illustrating the normal operation of the electromechanical actuator 1C when the first electric motor 3 is driven. Referring to FIG. 15, during normal operation using the first electric motor 3, the first motion conversion mechanism 6 operates in a state in which the third shaft 34 of the second motion conversion mechanism 8 is locked by the torque limiter 200. This moves the output portion 12 in the axial direction X1.
[0043] More specifically, in the torque limiter 200, the pressure force adjusting member 211 presses the opposed members 207,208. This disables the relative rotation of the opposed members 207,208, which are coupled to each other. with the balls 209 located between the two. The rotation of the gear 204, which is coupled to the opposite element 207, is therefore restricted. This locks the third shaft 34. In other words, the rotation of the third shaft 34 is restricted. In this situation, when the first electric motor 3 is running, the rotation (for example, indicated by the arrow D301 in Fig. 15) of the output shaft 3b of the first electric motor 3 is transmitted to the first shaft 28 by the intermediate of the first 5C force transmission mechanism. This rotates the first shaft 28 about the central axis Si in the direction indicated by the arrow D302 in FIG. 15. When the first shaft 28 is rotated, the rotation of the first member 29 is converted into linear motion of the second member 31. This moves the output portion 12, which is formed integrally with the second member 31, into the axial direction X1 (for example, the direction indicated by the arrow D303 in Fig. 15).
[0044] In this case, the rotation of the fourth element 35 (third shaft 34) is restricted. The third element 33 is therefore rotated relative to the fourth element 35 (third shaft 34) and moves in the axial direction X1. More specifically, the output portion 12 moves in the axial direction X1 of the total amount of the axial displacement of the output portion 12 when the first member 29 of the first motion conversion mechanism 6 is rotated relative to the second member 31 and axial displacement of the first shaft 28 when the third member 33 of the second motion conversion mechanism 8 is rotated relative to the fourth member 35. (B) Operation when the First Motion Conversion Mechanism is Stuck FIG. 16 is a diagram illustrating the operation of the electromechanical actuator 1C when the first motion conversion mechanism 6 is jammed. Referring to FIG. 16, when the first motion conversion mechanism 6 is jammed, the second braking mechanism 11 releases the lock. This allows a force applied from outside the electromechanical actuator 1C to move the output portion 12 in the axial direction X1. More specifically, jamming may occur in the first motion conversion mechanism 6, for example, when a foreign material is taken between the first member 29 and the second member 31 (the jammed location is indicated by the symbol J1 on the Fig. 16). This disables the relative movement of the first and second members 29, 31. Accordingly, the axial movement of the output portion 12 is disabled. However, when a force from the flight control surface 102 is input to the output portion 12, the output portion 12 acts to move in the axial direction X1. Accordingly, the second shaft 30 acts to move integrally with the first shaft 28 in the axial direction X1 (for example, the direction of the arrow D304 in Fig. 16). Accordingly, a thrust force F1 shown in FIG. 16 is applied to the third shaft 34 from the first shaft 28. The thrust force F1 acts on the third shaft 34 as a force acting to rotate the third shaft 34, for example, in a direction of the arrow D305 on the Fig. 16. However, such a rotational force of the third shaft 34 caused by the thrust force F1 is received by the torque limiter 200.
[0045] Then, when the pushing force F1 acting on the third shaft 34 from the first shaft 28 reaches or exceeds a predetermined value, the rotational force of the third shaft 34 causes the force acting between the opposed elements 207, 208 of the speed limiter. torque 200 exceeds the biasing force of the spring member 210. The opposite member 207 thus compresses the spring member 210. This increases the distance between the opposed members 207, 208. The balls 209 held between the opposed members 207, 208 rolls between the opposed members 207,208. The opposite member 208 rotates freely relative to the opposite member 207 as indicated by the arrow D306 in FIG. 16. This allows the third shaft 34 (fourth member 35) to rotate about the first shaft 28. Accordingly, the first shaft 28 (output portion 12) moves in the axial direction X1. The output portion 12 is movable in the axial direction X1 even in case of jamming. (C) Operation When the Second Mechanism of Motion Conversion is Stuck FIG. 17 is a diagram illustrating the operation of the electromechanical actuator 1C when the second motion conversion mechanism 8 is jammed. Referring to FIG. 17, when the second motion conversion mechanism 8 is jammed, the torque limiter 200 releases the lock. This allows a force applied from outside the electromechanical actuator 1C to move the output portion 12 in the axial direction X1. More specifically, jamming may occur in the second motion conversion mechanism 8, for example, when a foreign material is taken between the third member 33 and the fourth member 35 (the jammed location is indicated by the symbol J2 on the Fig. 17). This disables the relative movement of the third and fourth members 33, 35. As a result, the axial movement of the output portion 12 is disabled. However, when a force from the flight control surface 102 is supplied input to the output portion 12, the output portion 12 acts to move in the axial direction X1. Accordingly, the second shaft 30 acts to move integrally with the first shaft 28 in the axial direction X1 (e.g., the direction of the arrow D304 in Fig. 17). Accordingly, a thrust force F1 shown in FIG. 17 is applied to the second shaft 30 from the first shaft 28. The thrust force F1 acts on the first shaft 28 as a force acting to rotate the first shaft 28, for example, in a direction of the arrow D306 on FIG. 17. However, the thrust force F1 is received by the torque limiter 200 through the second motion conversion mechanism 8 and the second force transmission mechanism 9C.
[0046] Then, when the pushing force F1 acting on the third shaft 34 from the first shaft 28 reaches or exceeds a predetermined value, the rotational force of the third shaft 34 causes the force acting between the opposing elements 207, 208 of the speed limiter. torque 200 exceeds the biasing force of the spring member 210. The opposite member 207 thus compresses the spring member 210. This increases the distance between the opposed members 207, 208. The balls 209 held between the opposed members 207, 208 rolls between the opposed members 207,208. The opposite member 208 rotates freely relative to the opposite member 207 as indicated by the arrow D307 in FIG. 17. This allows the third shaft 34 and the first shaft 28 to rotate about the central axis Si. As a result, the first member 29 of the first shaft 28 is rotated relative to the second member 31 of the second shaft 30. This moves the second shaft 30 (output portion 12) in the axial direction X1. The output portion 12 is movable in the axial direction X1 even in case of jamming. As described above, in the electromechanical actuator 1C of the present embodiment, the torque limiter 200 is configured to be able to change the predetermined value, which serves as a maximum torque value which restricts the relative rotation of the opposed elements. , 208. In this structure, when the first element 29 and the second element 31 are locked, a torque exceeding the predetermined value can be applied between the third element 33 and the fourth element 35 via the first element 29 and the second element 29. In such a case, the relative movement of the third member 33 and the fourth member 35 can move the first member 29 and the second member 31 in the axial direction X1. This limits an excessive force input to each of the motion conversion mechanisms 6, 8.
[0047] In the electromechanical actuator 1C, when the torque acting between the third member 33 and the fourth member 35 is less than the predetermined value, the relative movement of the third member 33 and the fourth member 35 is restricted. As a result, the second member 31 can be moved in the axial direction X1 as the first member 29 and the second member 31 move relative to each other. When the torque acting between the third element 33 and the fourth element is greater than or equal to the predetermined value, the relative movement of the third element 33 and the fourth element 35 is allowed. This allows axial movement of the third member 33 as the fourth member is rotated, thereby limiting an excessive load applied to the third member 33 and the fourth member 35. This also limits an excessive load applied to the flight control surface 102 and to a part to which the electromechanical actuator 1C is coupled. The electromechanical actuator 1C adjusts an applied pressure force from the pressure force adjusting member 211 to the spring member 210.
[0048] This sets the maximum value (predetermined value) of the torque acting between the third element 33 and the fourth element 35. The maximum value (predetermined value) of the torque acting between the third element 33 and the fourth element 35 can be adjusted using a structure in which a solenoid is used as the pressure force adjusting member 211. To provide redundancy, a plurality of electromechanical actuators 1C may be arranged in a flight control surface at 102. In this case, when one of the electromechanical actuators 1C is stuck, another electromechanical actuator 1C may drive the flight control surface 102. In this case, the controller may reduce a load applied to the electromechanical actuator 1C driving the flight control surface 102 by actuating the pressure force adjusting member 211 of the electromechanical actuator 1C stuck, pl us specifically, by changing the amount protruding from the rod 211a. Fifth Embodiment FIG. 18 is a schematic side view partially in section of an electromechanical actuator 1D according to a fifth embodiment of the present invention. Referring to FIG. 18, in the present embodiment, a first 6D motion conversion mechanism uses a screw as the first member 29D, which is rotated by the first electric motor 3. A second 8D motion conversion mechanism uses a nut as the third element 33D, which is movable integrally with the first element 29D. The electromechanical actuator 1D of the present embodiment comprises the first electric motor 3, the first braking mechanism 4, the first force transmission mechanism 5, the first motion conversion mechanism 6D, the rotation stop mechanism 7 , the second motion conversion mechanism 8D, the second force transmission mechanism 9, the second electric motor 10, and the second braking mechanism 11.
[0049] The first motion conversion mechanism 6D comprises a first shaft 28D, the first member 29D operating as a first screw, a second shaft 30D, and a second member 31D operating as a first nut which is attached to the first member 29D.
[0050] The first member 29D is a male threaded member formed at one end of the first shaft 28D. The outer circumference of the first shaft 28D includes a straight-toothed portion 32D. The second member 31D is a nut member which is formed at one end of the second shaft 30D and is attached to the first member 29D. The second motion conversion mechanism 8D comprises the third element 33D and a fourth element 35D. The third element 33D functions as a second nut configured to be movable integrally with the first element 29D. The fourth element 35D operates as a second screw which is attached to the third element 33D. The third member 33D is a nut member formed at the other end of the first shaft 28D. The fourth member 35D is a male threaded member which is formed on the third shaft 34D and is attached to the third member 33D. The fourth element 35D (third shaft 34D) is connected to the second electric motor 10 and to the second braking mechanism 11 via the second force transmission mechanism 9.
[0051] In this structure, the second braking mechanism 11 is configured to be able to selectively perform an operation that restricts the rotation of the fourth member 35D as the third member 33D moves, and an operation that allows rotation of the fourth member 35D. when the third element 33D moves.
[0052] This structure also obtains the same advantages as the first embodiment. Embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments and may be embodied in many other specific forms without deviating from the spirit or scope of the present invention. For example, the present invention may be implemented in the following modified examples. (I) The above embodiments describe an example in which the first to fourth elements are screws and nuts. However, there is no limit to this configuration. For example, as shown in FIG. 19, each motion conversion mechanism may be a ball screw mechanism. In this case, a first member 29E of a first motion conversion mechanism 6E is a female threaded groove helically formed in the first shaft 28. A second member 31E is a male threaded groove formed helically in the first shaft 28. second shaft 30. A plurality of balls 80 functioning as rolling elements is arranged between the first element 29E and the second element 31E. The balls 80 are configured to flow through a groove portion between the first member 29E and the second member 31E. In addition, a third member 33E of a second motion conversion mechanism 8E is a male threaded groove formed helically in the first shaft 28. A fourth member 35E is a female threaded groove formed helically in the third shaft 34. A plurality of balls 81 functioning as rolling members is arranged between the third member 33E and the fourth member 35E. The balls 81 are configured to flow through a groove portion between the third member 33E and the fourth member 35E. (II) As shown in FIG. 20, the motion conversion mechanisms 6F, 8F, which are roller screw mechanisms, can be used in place of the motion conversion mechanisms 6, 8. The first motion conversion mechanism 6F comprises a plurality of first elements 29F, a second member 31F, and a plurality of rollers 83. The first members 29F are each a female threaded groove formed helically in an inner circumference of the first shaft 28. The rollers 83 are arranged in the inner circumference of the first shaft 28 at equal intervals in the circumferential direction of the first shaft 28 (Fig. 20 is only a roll 83). Each roller 83 comprises a male threaded groove helically formed in the outer circumference. The rollers 83 mesh with the first elements 29F and the second element 31F. Each roller 83 is able to rotate about the central axis of the roller 83 and to orbit around the central axis Si. The second member 31F is a female thread groove helically formed in the outer circumference of the second tree 30.
[0053] The second motion conversion mechanism 8F includes a third member 33F, a fourth member 35F, and a plurality of rollers 84. The third member 33F is a male threaded groove formed helically in the outer circumference of the first shaft 28. The rollers 84 are arranged in the inner circumference of the third shaft 34 at equal intervals in the circumferential direction of the third shaft 34 (Fig. 20 is only a roll 84). Each roller 84 includes a male threaded groove helically formed in the outer circumference. Each roll 84 meshes with the third member 33F and the fourth member 35F. Each roller 84 is able to rotate about the central axis of the roller 84 and to orbit around the central axis Si. The fourth member 35F is a female threaded groove formed helically in the inner circumference of the third Shaft 34. (III) The above embodiments describe an example of a speed summation operation that increases a momentum of the output portion 12 using the motion conversion mechanisms 6, 8 by the driving the first electric motor 3 and the second electric motor 10. However, there is no limit to this configuration. For example, the output portion 12 may be configured to move in one direction when the first motion conversion mechanism 6 is driven by the driving of the first electric motor 3, and in the reverse direction when the second conversion mechanism of movement 8 is driven by driving the second electric motor 10. In this case, the output portion 12 performs a speed subtraction operation. In the speed subtraction operation, the output portion 12 moves in the axial direction by an amount obtained by subtracting the displacement of the output portion 12 when the first electric motor 3 is driven, the movement of the portion of the output 12 when the second electric motor 10 is driven. (IV) The embodiment using the torque limiter describes an example of a torque limiter which comprises two opposing elements and balls arranged between the opposed elements. However, there is no limit to this configuration. For example, the torque limiter may be replaced by a different mechanism, for example a tilt brake. (V) The above embodiments describe an example of an electromechanical actuator used for an aircraft. However, there is no limit to this configuration. The present invention may be applied in a field other than aircraft. The present examples and embodiments should be considered illustrative and not restrictive, and the invention should not be limited to the details given herein, but may be varied according to the scope and equivalence of the appended claims.
[0054] Industrial Applicability The present invention can be applied broadly to an electromechanical actuator comprising a motion conversion mechanism which converts a rotational driving force, which is outputted by an electric motor, into a linear drive force and outputs the linear drive force.

权利要求:
Claims (16)
[0001]
REVENDICATIONS1. An electromechanical actuator (1) comprising: a first electric motor (3); a first motion conversion mechanism (6); a second motion conversion mechanism (8); and a rotation restriction mechanism (11) for the second motion conversion mechanism (8), wherein: the first motion conversion mechanism (6) comprises a first screw and a first nut which is attached to the first screw ; the second motion conversion mechanism (8) comprises a second screw and a second nut which is attached to the second screw; the first motion conversion mechanism (6) comprises a first member (29) which includes one of the first screw and the first nut, the first member (29) being rotated by an output of the first electric motor (3). ), and a second element (31) which comprises the other one of the first screw and the first nut; the second motion conversion mechanism (8) comprises a third element (33) which comprises one of the second screw and the second nut, the third element (33) being movable integrally with the first element (29), and a fourth member (35) which includes the other of the second screw and the second nut; and the rotation restriction mechanism (11) is configured to be able to selectively perform an operation which restricts the rotation of the fourth member (35) as the third member (33) moves, and an operation which allows the rotation the fourth element (35) when the third element (33) moves.
[0002]
An electromechanical actuator (1) according to claim 1, wherein each motion conversion mechanism (6, 8) is formed using one of a roller screw and a ball screw.
[0003]
An electromechanical actuator (1) according to claim 1 or 2, further comprising: a gear (5d) which is rotated upon receipt of the output of the first electric motor (3); and teeth (32) which are configured to mesh with the gear (5a-5d) and integrally rotate with the first member (29), wherein the teeth (32) form grooves extending into a axial direction of the first element (29).
[0004]
An electromechanical actuator (1) according to any one of claims 1 to 3, further comprising a rotation stop mechanism (7) which restricts rotation of the second member (31).
[0005]
An electromechanical actuator (1) according to any one of claims 1 to 4, further comprising a first hollow shaft (28), wherein the first shaft (28) comprises the first member (29) and the third member (33). ) which are arranged in a straight line.
[0006]
An electromechanical actuator (1) according to claim 5, further comprising: a second shaft (30) which is inserted into the first shaft (28); and a third shaft (34) surrounding the first shaft (28), wherein the first nut that functions as the first member (29) and the first screw that functions as the second member (31) are respectively arranged on a inner circumference of the first shaft (28) and an outer circumference of the second shaft (30), and the second screw which functions as the third element (33) and the second nut which functions as the fourth element (35) are arranged respectively on an outer circumference of the first shaft (28) and an inner circumference of the third shaft (34).
[0007]
An electromechanical actuator (1) according to any one of claims 1 to 6, further comprising: a housing (2) which houses the fourth member (35); and a bearing unit (36) which is held by the housing (2) and supports the fourth member (35), wherein the bearing unit (36) comprises a thrust bearing (37) and a radial bearing (38). ) which are coaxial with the fourth element (35).
[0008]
The electromechanical actuator (1) according to any one of claims 1 to 7, further comprising a second electric motor (10) which is capable of driving and rotating the fourth member (35).
[0009]
The electromechanical actuator (1) according to claim 8, further comprising a rotation restriction mechanism (4) for the first motion conversion mechanism (6), the rotation restriction mechanism (4) for the first rotation mechanism (4). motion conversion (6) being arranged to restrict the rotation of the first member (29).
[0010]
An electromechanical actuator (1) according to any of claims 1 to 9, wherein the rotation restriction mechanism (11) for the second motion conversion mechanism (8) comprises a braking mechanism which is capable of restricting rotating the fourth element (35).
[0011]
The electromechanical actuator (1) according to claim 10, wherein the braking mechanism of the rotation restriction mechanism (11) for the second motion conversion mechanism (8) comprises a torque limiter (200) which is capable of restricting the rotation of the fourth member (35) when the torque acting on the fourth member (35) is less than a predetermined value, and the torque limiter (200) is configured to be able to change the predetermined value.
[0012]
An electromechanical actuator (1) according to claim 11, wherein the torque limiter (200) comprises two opposing members (207, 208), which are opposed to each other, and a force adjusting member (20). pressure (211), the two opposing members (207, 208) are coupled to the fourth member (35) and the pressure force adjusting member (211), the two opposing members (207, 208) are configured to be coupled so that the transmission of force between the two opposite members (207, 208) is permitted when the torque acting between the two opposed members (207, 208) is less than a predetermined value, the two opposing members (207, 208). ) are configured to freely rotate relative to each other when the torque acting between the two opposite members (207, 208) is greater than or equal to the predetermined value, and the pressure force adjusting member (211) ) is configured to be able to adjust a thrust load acting between the two opposing elements (207, 208).
[0013]
An electromechanical actuator (1) according to claim 12, further comprising a spring member (210) located between one of the two opposing members (207, 208) and the pressure force adjusting member (211), wherein the pressure force adjusting member (211) is configured to be capable of adjusting a pressing force which urges the spring member (210) against the opposite member (207, 208).
[0014]
An electromechanical actuator (1) according to claim 12 or 13, wherein the pressure force adjusting member (211) comprises a solenoid.
[0015]
The electromechanical actuator (1) according to any one of claims 1 to 7, wherein the rotation restriction mechanism (11) for the second motion conversion mechanism (8) further comprises a second mechanism torque limiter motion converter (44) which is located between the first electric motor (3) and the fourth element (35), the torque limiter of the second motion conversion mechanism (44) comprises two opposite second elements (63, 64). which are capable of transmitting a force to the first electric motor (3) and to the fourth element (35), the two opposite second elements (63, 64) are configured to be coupled such that the power transmission between the two opposing second elements (63, 64) is permitted when the torque acting between the first electric motor (3) and the fourth element (35) is less than a predetermined value, and the second two the opposed elements (63, 64) are configured to freely rotate relative to one another when the torque acting between the first electric motor (3) and the fourth element (35) is greater than or equal to the predetermined value.
[0016]
The electromechanical actuator (1) according to claim 15, further comprising a torque limiter of a first motion conversion mechanism (43) located between the first electric motor (3) and the first element (29), wherein the limiter of torque of first motion conversion mechanism (43) comprises two first opposed elements (53, 54), one of which is coupled to the first electric motor (3) and the other of which is coupled to the first element (29), the first two opposing members (53, 54) are configured to be coupled so that the transmission of force between the first opposing members (53, 54) is permitted when the torque acting between the first electric motor (3) and the first element (29) is less than a predetermined value, and the first two opposing elements (53, 54) are configured to freely rotate relative to each other when the torque acting between the first electric motor that (3) and the first element (29) is greater than or equal to the predetermined value.

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同族专利:

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公开号 | 公开日

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US20150308549A1|2015-10-29|

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US9765867B2|2017-09-19|

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FR3020431B1|2020-03-06|

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JP6594648B2|2019-10-23|

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JP2015216837A|2015-12-03|

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法律状态:
2016-04-23| PLFP| Fee payment|Year of fee payment: 2 |

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2017-05-02| PLFP| Fee payment|Year of fee payment: 3 |

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2018-04-26| PLFP| Fee payment|Year of fee payment: 4 |

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2019-03-01| PLSC| Search report ready|Effective date: 20190301 |

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2019-04-23| PLFP| Fee payment|Year of fee payment: 5 |

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2020-04-20| PLFP| Fee payment|Year of fee payment: 6 |

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2021-04-23| PLFP| Fee payment|Year of fee payment: 7 |

优先权:

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申请号 | 申请日 | 专利标题

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JP2014089490|2014-04-23|

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JP2014089490|2014-04-23|

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