• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    ABSTRACT. This invention relates to a linear actuator, comprising an electric motor (10), a worm gear (13, 14), a transmission (15, 16, 19), an outer tube (2) and a spindle (12), said spindle (12) being in connection with the transmission (15, 16, 19), a spindle nut (11) on the spindle (12), a thrust bearing (20) for supporting a shaft end (21) of the spindle (12), wherein the connection between the shaft end of the spindle (12) and the transmission (15, 16, 19) allows a mutual axial movement so that axial forces are only lead through the spindle (12) bypassing the transmission (15, 16, 19) and directly to the thrust bearing (20), wherein a support structure (17, 18, 24, 28) fixedly connects the outer tube (2) and a lower bracket (20, 22), wherein said worm gear (13, 14) drives a shaft (19) included in said transmission (15, 16, 19), which shaft (19) has a driving gear wheel (15) fixedly attached thereto, arranged to transmit torque to a driven gear wheel (16) fixedly attached to the spindle (12), wherein said transmission (15, 16, 19) is arranged to allow axial displacement of the driven gear wheel (16) in relation to the driving gear wheel (15).(Fig2)
    公开号:SE1650242A1
    申请号:SE1650242
    申请日:2016-02-24
    公开日:2017-08-25
    发明作者:Olsson Johan
    申请人:Reac Ab；
    IPC主号:
    专利说明:

    LINEAR ACTUATOR DEVICE TECHNICAL FIELD The present invention relates to a linear actuator device, comprising an electric motor, aworrn gear a transmission, an outer tube and a spindle, said spindle being in connectionwith the transmission, a spindle nut on the spindle, a thrust bearing for supporting ashaft end of the spindle, wherein the connection between the shaft end of the spindleand the transmission allows a mutual axial movement so that axial forces are only leadthrough the spindle bypassing the transmission and directly to the thrust bearing and wherein a support structure fixedly connects the outer tube and a lower bracket.
    BACKGROUND ART Linear actuators are well-known components for use in machines and control devices,not at least they are widely used within the hospital and care sectors, where they areused for adjustable fumiture such as patient lifting devices, beds etc. In this kind ofapplications, the linear actuator transfers a force between the attachment points of the actuator.
    The construction of linear actuators, which can transfer the forces between the twoattachment points without overloading the transmission and thus causing wearing, isdifficult and often results in the construction being complicated and expensive. Furtherit mostly is more voluminous than desired. This is particularly the case where the linearactuator is equipped with a transmission, which comprises a planetary gear, since theconfiguration of a worrn gear driving the sun gear of the planetary gear, will alwaysresult in a motor orientation perpendicular to the actuator main axis.
    WO 98/30816, US 8410731 and US 8308603 disclose linear actuators where thetransmission comprises a planetary gear, e. g. implying many components. Manycomponents mean more expenses for material and production and that the linear actuator becomes voluminous.
    The purpose of the invention is to provide a solution to the outlined problem, i.e. toachieve a linear actuator which is capable of leading the axial forces in the actuatoraround the transmission and that is cost-efficient, and that may provide a more compact and/or simple construction.
    SUMMARY OF THE INVENTION The main object of the present invention is to provide a linear actuator which eliminates or at least minimizes any or some of the problems mentioned above, which is achieved in accordance with a device in accordance with claim l.
    Thanks to the invention there is provided a more compact linear actuator, which moreover is simple in its construction and which is capable of leading the axial forces in the actuator through the transmission, bypassing the gear wheels, i.e. without any substantial axially reaction forces from the load acting upon the gear wheels.
    According to further aspects of the invention it may be preferred; that said gear wheels are spur gear wheels, which provides the advantage that the axial displacement may be achieved at minimal cost. that said driven gear wheel is fixedly attached to a hub, which hub is arranged with adisplacement limiting member arranged to form a gap in relation to said supportstructure defining an upper stop limit for said displacement, which provides theadvantage that an easy and cost efficient technical solution may be provided for a safe and secure device. that a lower stop limit of said gap is achieved by having said shaft end of the spindleabutting the thrust bearing, which also provides the advantage that an easy and cost efficient technical solution may be provided for a safe and secure device that a control sensor is arranged to sense an axial motion of said spindle and to stopthe motor in connection with sensing a predeterrnined maximum alloweddisplacement that is equal to or less than said gap, which also provides theadvantage that an easy and cost efficient technical solution may be provided for a safe and secure device. that said control sensor is arranged with a stop contact member arranged to contactthe driven spur gear wheel in connection with reaching said predeterrninedmaximum allowed displacement, which also provides the advantage that an easy and cost efficient technical solution may be provided for a safe and secure device. - that said support structure is arranged in a manner that also provides the advantagethat an easy and cost efficient technical solution may be provided for a safe and secure device.
    BRIEF DESCRIPTION OF THE DRAWINGSIn the following, the invention will be described in more detail with reference to preferred embodiments and the appended drawings, where, Fig. 1 shows a perspective view of an embodiment according to the invention,Fig. 2 shows a cross sectional view of a part of a linear actuator device according to the invention, and,Fig. 3 shows a schematic view of an altemate embodiment of the invention.DETAILED DESCRIPTION In Fig 1 there is shown patient lifting equipment including a basic support structure 5, 9and lifting members 4, 8 of a well-known kind. The patient lifting device includes alinear actuator 1, 2, 3 that via control equipment 6, 7 may assist in lifting a patient bymeans of the lifting members 4, 8. Fig. 1 demonstrates an example of use of theinvention, wherein the invention may provide substantial advantages compared to the use of known linear actuators.
    In Fig. 2 there is shown a cross sectional schematic view of a linear actuator accordingto a preferred embodiment of the invention. It is shown that the linear actuator ispowered by an electric motor 10, which as shown in Fig. 1 norrnally is positionedwithin a housing 1. The electrical motor 10 powers a motor axis, having a worrn 13 thatin tum transmits torque to a worrn gear wheel 14. The worrn gear unit 130 is fixedlyattached to a first support wall 17. In the support wall 17 there is a passage 170 throughwhich a shaft 19 extends, which shaft 19 is powered by the worrn gear wheel 14.
    At the end of the worrn gear shaft 19 there is attached a first spur gear wheel 15. Thisspur gear wheel 15 is arranged to directly transmit torque to a second spur gear wheel16. The second spear gear wheel 16 is fixedly connected to a hub 161 (e. g. by means ofbeing integrated or screw attached) that is fixedly attached to the end of a spindle 12.The fixation of the hub 161 is achieved by means of splines (or some other torque transferring arrangement, e. g. wedge) in combination with a spindle end cap 21. The spindle end cap 21 has a rear abutment surface 210 that abuts a trust bearing 20. The trust bearing 20 is secured within a lower actuator mount 22.
    The lower actuator mount 22 is fixedly attached to a second support wall 18. Thesecond support wall 18 is fixedly connected at distance from the first support wall 17,by means of attachment members 28. The spur gear wheels 15, 16 will be positionedwithin the space delimited by the support walls 17, 18. The second support wall 18 hasa passage 180 for the end part of the spindle 12, here in the form of an end cap 21attached to the spindle 12. A bearing member 23 is arranged between the outer periphery of the end cap 21 and the passage 180 in the second wall 18.
    On the spindle 12 there is arranged a spindle nut ll. On the spindle nut 11 there isarranged an inner tube 3. The inner tube 3 is moveable together with the spindle nut ll, within an outer tube 2.
    The outer tube 2 has its rear end 200 fixedly attached to the first wall member 17. Thespindle 12, the hub 161 and the spindle end cap 21 are axially moveable arranged apredeterrnined limited distance, within a gap G. This is achieved by having the hub 161arranged with a first displacement limiting member 160, here in the form an edge, thatis positioned at a distance (corresponding to the gap G, when the spindle 12 is in its rearmost position) from an upper stop limit 27, here in the form a lower end 240 of an upperspindle bearing 24. The upper spindle bearing 24 is fixedly attached to the first supportwall 17 within a second passage 171, adapted for the bearing 24 and the spindle 12. Thelower stop limit 29 of the play G is in this embodiment achieved by having a lowerabutment surface 210 of the end cap in contact with the trust bearing 20. Accordingly,the spindle 12 may be moved within a gap G by applying a pulling force to the spindle12, which will move the abutment surface 210 away from the trust bearing 20 and movethe spindle, the hub 161 and end cap 21 until the edge 160 of the hub 161 is contactingthe lower end 240 of the second spindle bearing 24. The outer way will be achievedautomatically, i.e. once load is applied it will push the spindle 12 in contact with the trust bearing 20.
    A control sensor 25, 26 is fixedly attached to the first support wall 17. This controlsensor 25, 26 has in this embodiment a contact member 26 that at its front end may bein contact with the driven gear wheel 16. Accordingly, when the spindle 12 is moved toclose the gap G the contact 26 will be pushed in by the driven gear wheel 16, thereby providing the ability to give signal at a predeterrnined position of displacement of the contact member 26. This may for instance be used to arrange for a motor stop controlsignal when a predeterrnined displacement of the contact member 26 has been reached, facilitating a down-force limit safety arrangement Accordingly, the invention presents a linear actuator device that comprises an electricalmotor 10 which operates a worrn gear 13, 14, which in tum transmits torque to a geartransmission 15, 16, 19, for rotation of the spindle 12, which in tum is transferred tolinear movement of the spindle nut 11 that controls the position of the inner tube 3. Theforce that is exerted by a load applied to the upper end of the inner tube 3 will then betransmitted directly via the spindle 12 to the trust bearing 20. Accordingly, no actualforces will be transferred to the transmission 15, 16 thanks to the use of axiallydisplaceable gear wheels, which also facilitates axial displacement of the driven spurgear wheel 16 in relation to the driving gear wheel 15. Thanks to having the driven gearwheel 16 attached to a hub 161 having a displacement limiting member 160 there maybe provided a gap G, in relation to the support structure 17, 18, 24, 28 such that thespindle 12 together with the driven spur gear wheel 16 and the end cap 21 may beaxially displaced, and further providing the advantage that the gear transmission facilitates a transfer of load directly on to the trust bearing 20.
    All in all, this provides a simple and reliable structure in comparison with known priorart, which provides many advantages, such as ease of maintenance and relatively low cost.
    In Fig. 3 there is shown a schematic perspective view of a further embodimentaccording to the invention, wherein the cross angle between driving and driven gears15, 16 will allow for having the motor 10 mounted axially along the outer tube 2 thusreducing overall size. This kind of solution is not possible if using a design as suggestedin the prior art, e.g. US 8308603. Most details are the same, i.e. fulf1l the samefunctions, as has already been described in connection with Fig. 2 and therefore there isa mere focus on different features. Here, the driving wheel 15 and the driven wheel 16do not have straight cut teeth, but instead helical teeth. It is preferred to position thehelical teeth such that a lifting reaction force will be transferred from the driving wheel15, to the driven wheel 16, in connection with moving the aid device 4, 8 downwardlyto thereby have that reaction force assisting in moving the driven wheel 16 against thesensor 25, 26. Otherwise there is a risk that the reaction force eliminates actuation of thedown-force limit safety arrangement. In the shown embodiment it means arranging the teeth such that a clockwise rotation of the driving wheel will rotate the driven wheel anti-clockwise in connection with moving the inner tube 3 downwardly. It will bepossible to move the spindle 12 axially in relation to the housing and the outer tube 2,whereby simultaneously with the axial movement the teeth will effect a small rotationalmovement of the spindle l2. However, this small rotation movement of the spindle l2will not cause any substantial counterforce, thereby fulfilling in principle the same basicfunction as described in connection with Fig. 2. In some applications it may be neededto arrange a resilient counter force between the driven wheel 16 and the supportstructure, to eliminate undesired stops caused by the reaction force, e.g. if the weight/ load acting on the spindle l2 is less than the reaction force. An advantage withthe embodiment shown in Fig. 3 is that the motor l2 can be positioned to extend in parallel with the spindle and the outer tube 2, which facilitates compact arrangement.
    The invention is not limited by the embodiments presented above, but may be variedwithin a plurality of aspects without departing from the basic principles of theinvention. For instance, it is evident that the resilient force that may be desired, may beimplemented in various forms, e.g. a helical spring, air cushions, resilient polymers, etc.Further it is evident that a variety of known per se devices/ so lutions may be used butstill maintain the basic principles of the solution according to the invention. Moreover,it is foreseen that principles of the solution presented in connection with Fig. 3 may bethe subject for its own protection, without limitation to the use of the preferred kind ofgear wheels as shown in Figs. l and 2, i.e. instead a focus on the novel arrangement of the motor and its attachment/ connection to the rest of the actuator.
    权利要求:
    Claims (13)
    [1] 1. A linear actuator, comprising an electric motor (10), a worrn gear (13, 14), atransmission (15, 16, 19), an outer tube (2) and a spindle (12), said spindle (12) being inconnection with the transmission (15, 16, 19), a spindle nut (11) on the spindle (12), athrust bearing (20) for supporting a shaft end (21) of the spindle (12), wherein theconnection between the shaft end of the spindle (12) and the transmission (15, 16, 19)allows a mutual axial movement so that axial forces are only lead through the spindle(12) bypassing the transmission (15, 16, 19) and directly to the thrust bearing (20),wherein a support structure (17, 18, 24, 28) fixedly connects the outer tube (2) and alower bracket (20, 22), c h ar a c t e r i z e d in that said worrn gear (13, 14) drives ashaft (19) included in said transmission (15, 16, 19), which shaft (19) has a driving gearwheel (15) fixedly attached thereto, arranged to transmit torque to a driven gear wheel(16) fixedly attached to the spindle (12), wherein said transmission (15, 16, 19) isarranged to allow axial displacement of the driven gear wheel (16) in relation to the driving gear wheel (15).
    [2] 2. A linear actuator according to claim 1, c h a r a c t e r i z e d in that said gear wheels (15, 16) are spur gear wheels.
    [3] 3. A linear actuator according to claim 1 or 2, c h a r a c t e r i z e d in that said drivengear wheel (16) is fixedly attached to a hub (161), which hub (161) is arranged with adisplacement limiting member (160) arranged to form a gap (G) in relation to saidsupport structure (17, 18, 24, 28) defining an upper stop limit (27) for said displacement.
    [4] 4. A linear actuator according to claim 3, c h a r a c t e r i z e d in that a lower stop limit(29) of said gap (G) is achieved by having said shaft end (21) of the spindle (12)abutting the thrust bearing (20).
    [5] 5. A linear actuator according to claim 2, 3 or 4, c h ar a c t e r i z e d in that a controlsensor (25, 26) is arranged to sense an axial motion of said spindle (12) and to stop themotor (10) in connection with sensing a predeterrnined maximum allowed axial displacement that is equal to or less than said gap (G).
    [6] 6. A linear actuator according to claim 5, c h a r a c t e r i z e d in that said control sensor (25, 26) is arranged with a stop contact member (26) arranged to contact the driven gear wheel (16) in connection with teaching said predeterrnined maximum allowed displacement.
    [7] 7. A linear actuator according to any preceding claim, c h a r a c t e r i z e d in that saidsupport structure includes first and second wall members (17, 18) arranged to providesupport for said worrn gear unit (130) and to provide space between the wall members(17, 18) for said gear wheels (15, 16).
    [8] 8. A linear actuator according to claim 7, c h a r a c t e riz e d in that there is a firstpassage (171) in the first wall member (17) and a second coaxial passage (180) in thesecond wall member (18), wherein said first passage (171) is arranged to form a firstcentering support for the spindle (12) and the second passage (180) is arranged to forma second centering support for the spindle (12).
    [9] 9. Method for operating a linear actuator, said linear actuator comprising a linearactuator, comprising an electric motor (10), a worrn gear (13, 14), a transmission (15,16, 19), an outer tube (2) and a spindle (12), said spindle (12) being in connection withthe transmission (15, 16, 19), a spindle nut (11) on the spindle (12), a thrust bearing (20)for supporting a shaft end (21) of the spindle (12), wherein the connection between theshaft end of the spindle (12) and the transmission (15, 16, 19) allows a mutual axialmovement so that axial forces are only lead through the spindle (12) bypassing thetransmission (15, 16, 19) and directly to the thrust bearing (20), wherein a supportstructure (17, 18, 24, 28) fixedly connects the outer tube (2) and a lower bracket (20, 22)characterized by using said worrn gear (13, 14) to drive a shaft (19) included in saidtransmission (15, 16, 19) and arranging said shaft (19) with a driving gear wheel (15)which transmits torque to a driven gear wheel (16) being fixedly attached to the spindleand wherein said transmission (15, 16, 19) facilitates axial displacement of the driven gear wheel (16) in relation to the driving gear wheel (15).
    [10] 10. Method according to claim 9, c h ar a ct e r i z e d b y the use of a displacementlimiting member (160) arranged to enable the driven gear wheel (16) to be moved axially within a predeterrnined gap (G).
    [11] 11. 1 1. Method according to claim 10, c h ar a c t e r i z e d b y having an upper stop limit(27) for said displacement when said displacement limiting member (106) contacts saidsupport structure (17, 18, 24, 28).
    [12] 12. Method according to c1aim 10 or 11, c h ar a ct e r i z e d b y arranging a 1oWer stop 1imit (29) for said axia1 disp1acement When a spind1e shaft end (21) abuts the thrustbearing (20).
    [13] 13. Method according to any of c1aims 9-12, c h ar a ct e r i z e d b y arranging a contro1sensor (25, 26) to sense actual movement of said spind1e (12) that stops the motor (10) in connection With sensing a predeterrnined maximum axia1 disp1acement.
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    同族专利:
    公开号 | 公开日
    EP3211769A1|2017-08-30|
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    DK151096A|1996-12-23|1998-07-17|Linak As|Linear actuator|
    US20050160846A1|2004-01-20|2005-07-28|Yi-Chung Chiang|Linear actuator|
    DE102005048394B3|2005-10-10|2007-02-15|Siemens Ag|Spindle drive for a patient support, to move up and down at a therapeutic/diagnostic machine, has a catch nut to engage the spindle on a failure through a worn spindle nut to prevent uncontrolled movement|
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    KR101764938B1|2009-10-29|2017-08-03|섀플러 테크놀로지스 아게 운트 코. 카게|Hydrostatic actuator|
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    TWI516693B|2013-05-15|2016-01-11|第一傳動科技股份有限公司|Linear actuator and speed adjustable quick release mechanism thereof|EP3439151A4|2016-03-30|2019-12-11|NTN Corporation|Electric actuator|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1650242A|SE539951C2|2016-02-24|2016-02-24|Linear actuator and a method for operating a linear actuator|SE1650242A| SE539951C2|2016-02-24|2016-02-24|Linear actuator and a method for operating a linear actuator|
    EP17155313.4A| EP3211769A1|2016-02-24|2017-02-09|Linear actuator device|
    US15/429,621| US10316945B2|2016-02-24|2017-02-10|Linear actuator device|
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