• 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:

    公开号:SE1250039A1
    申请号:SE1250039
    申请日:2012-01-23
    公开日:2013-07-24
    发明作者:Jan Dellrud；Joseph Ah-King；Tony Sandberg
    申请人:Scania Cv Ab；
    IPC主号:
    专利说明:

    15 20 25 30 2 spin or slip conditions. When the conditions exceed a threshold, the system automatically controls the application of a torque to the drive shaft by controlling the applied torque from a retarder acting on the drive shaft. The system can also automatically engage the differential lock if a wheel spinning threshold is exceeded and the corresponding wheel speed is lower than a predetermined threshold.
    GB-2,414,525 describes a vehicle which comprises a differential control device which controls the degree of engagement of the differentials of the vehicle, and a brake control system. If the brake control system reduces the braking action on a sliding wheel and the wheel continues to slide, it emits a signal to the differential control device which locks the differential, thereby increasing the rotational speed of the sliding wheel.
    US-6,485,111 relates to a method of controlling a retarder braking system for a vehicle. By measuring a wheel speed value for each wheel on the vehicle, a value indicating whether any of the wheels are sliding can be determined. Based on this value, a value of a reduced braking force of the retarder is determined, and a command for the reduction of the braking force of the retarder can thereby be issued to prevent any wheel from slipping.
    The method in US-6,485, 11l also includes that when sliding on one of the driving wheels is found to be able to synchronize the rotation of the rear drive wheels in connection with retarder braking.
    The object of the present invention is to provide an improved braking system for a vehicle, which is specially adapted for a situation where one or more of the wheels of the vehicle slip during braking using a retarder brake.
    Summary of the Invention The above objects are achieved by the invention defined by the independent claims.
    Preferred embodiments are defined by the dependent claims. 10 15 20 25 30 3 When the brake steering system detects that one of the drive wheels is slipping during retarder braking, the steering system can, instead of deregulating the retarder, engage the differential lock. Then, in the practice of the present invention, the overall braking level will be able to be maintained higher by utilizing the best bracket. As a result, the service brakes need to be used less, which is advantageous.
    The invention provides an improved steering and control of available braking force in connection with retarder braking which is achieved by calculating the maximum braking force available for the wheel which slides. This is determined by taking into account the deceleration speed of the wheel in connection with the slippage occurring and also the moment of inertia of the wheel. Once the available braking force has been calculated, a control signal for the differential synchronization system is determined, indicating the extent to which the sliding wheel must be forced to rotate in order to be able to utilize the available braking force, which in particular depends on the tire's friction to the road surface. The relationships between different available braking forces and the associated degree of engagement of the differential synchronization system can, for example, be given in a table.
    When applying the present invention, it is achieved, among other things, that wear reduces the brake pads, which results in fewer pad changes, which gives an improved operating time.
    According to an embodiment of the invention, the control of the engagement of the differential synchronization system is combined with an optimized control of the retarder brake system.
    Brief Description of the Drawings Figure 1 is a schematic block diagram illustrating the present invention.
    Figure 2 is a flow chart illustrating the method of the present invention.
    Figure 3 is a fate diagram illustrating an embodiment of the method of the present invention.
    Detailed Description of Preferred Embodiments of the Invention Referring to the schematic block diagram of Figure 1, the present invention will now be described. According to the invention, a vehicle, e.g. a truck, a retarder brake system 2, which may be, for example, a hydraulic retarder or an induction-based system. The vehicle further comprises a brake control system 4 and a differential synchronization system 6 adapted to synchronize the rotation between wheels on the same axle.
    Wheel rotation sensors 8 are provided which are adapted to measure the rotational speed of the respective wheels on the vehicle and generate wheel rotation signals 10 in dependence thereon, and a detector unit 12 adapted to receive said wheel rotation signals 10.
    The detector unit is further adapted to calculate the difference between the rotations between different wheels, compare the calculated difference with one or fl your predetermined threshold levels and generate one or fl your slip signals 14 depending on the result of this comparison. The difference in rotational speeds can, for example, be calculated between a driving wheel and a front wheel.
    The brake control system 4 comprises a calculation unit 16 adapted to receive the one or more sliding signals 14 and signals regarding the current braking torque MB for the respective wheels. The calculation unit 16 may further be adapted to receive a brake request 18, comprising a requested braking force, generated by the driver of the vehicle, and a speed signal 20 indicating the current speed of the vehicle. These signals are transmitted to the brake control system, for example via the vehicle's CAN bus (Controller Area Network).
    The calculation unit 16 is adapted to calculate a differential control signal 22 in dependence on said applied signals and where the calculations are adapted to be performed according to a set of control rules regarding the differential synchronization system 6.
    The differential control signal 22 includes commands indicating the degree of synchronism between wheels on the same axle, i.e. the degree of concurrency in the rotation.
    In connection with braking with the retarder braking system 2, the calculation unit 16 is adapted to calculate a currently available braking torque Mp for a sliding wheel. Based on this value of the available braking torque MB, the calculation unit determines by means of the control rules a degree of engagement of the differential synchronizing system 6 so that the requested braking torque MB is achieved, the differential control signal 22 being adapted to control the engagement of the differential synchronizing system 6. with the sliding wheel depending thereon.
    The set of control rules preferably comprises a table with the desired transmission of torques (MB - MB) through the differential synchronization system and the associated degree of connection of the differential synchronization system.
    The available braking force for the sliding wheel depends on the current friction of the tire to the ground. By measuring the deceleration speed of the wheel that begins to slide, the available braking force for the wheel can be determined. The difference in rotational speed change Avw compared to wheels that do not slide, e.g. the front wheels, multiplied by the moment of inertia TW of the wheel corresponds to the difference between the requested braking torque on the wheel MB and the available braking torque MB. The moment of inertia TW for the wheel is known in advance and can be stored as a parameter in the calculation unit 16.
    If the wheel does not slide, the friction between the tire and the road is high enough to absorb the entire braking torque and the wheel therefore rolls on the ground and has the same deceleration speed as the rest of the wheels.
    The braking torque that can be achieved for a wheel with the available friction is thus calculated according to the formula: MF = MB-AVWXTW where MB is the highest available braking torque for the wheel that slides.
    MB is the requested braking torque for the sliding wheel. 10 15 20 25 30 6 Avw is a difference in rotational speed change between the sliding wheel and the wheel on the same axle, and TW is the moment of inertia of the wheel.
    Based on MF, with said control rules, a degree of engagement of the differential synchronizing system 6 is determined so that the sliding wheel exerts the most braking torque MF, and that the differential steering signal 22 controls the engagement of the differential synchronizing system 6 for the shaft with the sliding wheel depending on the determined degree of engagement so that the sliding wheel begins to rotate and exerts the braking torque MF.
    As discussed above, a conventional braking system when it is found that a wheel is slipping would regulate the retarder braking so that it is less than the number of engaged driving wheels multiplied by MF so that no wheel will lose grip. This results in a greatly reduced braking effect.
    The basic idea of the present invention is thus to try to continue braking with the requested braking effect, but to distribute it on the wheels that have a bracket. In the case where this is done by means of a differential synchronization system, the differential would be controlled so that the difference between MB and MF is transferred from the sliding wheel to that with bracket and the two wheels rotate at the same speed.
    The sliding signal is generated, by the detector unit, if the wheel rotation speed is below a first variable threshold level, i.e. if the wheel rotates more slowly than this threshold level, or stands completely still. This threshold level depends on the current speed of the vehicle so that the threshold value at high speed is relatively high and at low speed relatively low. Furthermore, the difference between the rotational speeds of different wheels should preferably exceed a second threshold level, i.e. the slip must be detectable with a relatively high degree of certainty.
    The difference in the rotational speed change Avw is calculated by the detector unit 12 for the lowest speed wheel during a predetermined time interval t, which is preferably in the order of 0.1-1 seconds. For a differential synchronization system with a differential brake, the command in the differential control signal indicates the degree of engagement thereof, i.e. how much torque can be transferred between the wheels.
    For a differential synchronization system with differential locking, you can only control whether it should be locked or not and if it is locked, as much torque is transmitted as is necessary for both wheels to spin equally fast.
    According to one embodiment, the calculation unit is further adapted to calculate a retarder control signal 24 and that the control rules indicate the interaction between the retarder brake system 2 and the differential synchronization system 6, and where the retarder control signal 24 includes commands indicating the degree of engagement of the retarder brake system. associated degree of engagement of the retarder brake system, together with degree of engagement of the differential synchronization system.
    The calculation unit is further adapted to determine, based on the calculated current available braking force for the sliding wheel, with said control rules, a degree of engagement of the retarder brake system, and the retarder control signal is adapted to control the engagement of the retarder brake system accordingly.
    According to one embodiment, the steering rules include rules adapted to increase the synchronism between wheels on the same axle at the same time as the retarding effect is reduced and adapted to the wheel with the worst braking effect.
    The present invention also relates to a method for a vehicle comprising a retarder brake system, a brake steering system, a differential synchronization system adapted to synchronize the rotation between wheels on the same axle. Furthermore, wheel rotation sensors are adapted to measure the rotational speed of each wheel on the vehicle and generate wheel rotation signals depending thereon. A detector unit is arranged adapted to receive the wheel rotation signals and calculate the difference between the rotations of wheels.
    The method will now be described with reference to the general fl fate diagram in Figure 2. The method comprises: - comparing the calculated difference with one or more predetermined threshold levels and generating a sliding signal depending on the result of this comparison, - receiving in a calculation unit one or fl your sliding signals and the current braking torque MB for each wheel, - calculate, if said sliding signal indicates that a wheel slides in connection with braking with the retarder brake system, a current available braking force Mp for the sliding wheel according to the formula: Mp = MB - Avw> < TW where Mp is the highest available braking torque for the wheel that slides; MB is the requested braking torque for the sliding wheel; Avw is the difference in rotational speed change between the sliding wheel and non-sliding wheels, TW is the moment of inertia of the wheel. The method further comprises: - determining, with a set of control rules, a degree of engagement of the differential synchronizing system so that the requested braking torque is achieved, - controlling, with a differential control signal, the engagement of the differential synchronizing system of the shaft with the sliding wheel connection.
    The sliding signal is generated, by the detector unit, if the wheel rotation speed is below a first variable threshold level, i.e. if the wheel rotates more slowly than this threshold level, or stands completely still. This threshold level depends on the current speed of the vehicle so that the threshold value at high speed is relatively high and at low speed relatively low. Furthermore, the difference between the rotational speeds of different wheels should preferably exceed a second threshold level, i.e. the slip must be detectable with a relatively high degree of certainty.
    The difference in rotational speed change Avw is calculated by the detector unit 12 of the lowest speed wheel during a predetermined time interval t.
    According to one embodiment, the set of control rules comprises a table with the desired transmission of torques (MB - Mp) through the differential synchronization system and the associated degree of engagement of the differential synchronization system. Figure 3 shows a schematic fate diagram illustrating a method according to an embodiment of the present invention.
    In addition to the steps mentioned above, the method further comprises calculating a retarder control signal and said control rules indicating interaction between said retarder brake system and differential synchronization system, and wherein the retarder control signal includes commands indicating the degree of engagement of the retarder brake system. According to this embodiment, the table with available braking force also includes the associated degree of engagement of the retarder braking system. The calculation unit is further adapted to determine, based on the calculated current available braking force for the sliding wheel, with said control rules, a degree of engagement of the retarder brake system, and the retarder control signal is adapted to control the engagement of the retarder brake system accordingly.
    Steering rules include rules that are adapted to increase the synchronism between wheels on the same axle at the same time as the retarder effect is reduced and adapted to the wheel with the worst braking effect.
    The present invention may be implemented as software, or implemented as one or more pieces of hardware, or as a combination of software and hardware.
    The invention then comprises a computer program product with program code for carrying out the various steps of the invention when the program code is run on a computer.
    The present invention is not limited to the above-described preferred embodiments.
    Various alternatives, modifications and equivalents can be used. The above embodiments are, therefore, not to be construed as limiting the scope of the invention as defined by the appended claims.
    权利要求:
    Claims (16)
    [1]
    A vehicle comprising a retarder brake system (2), a brake control system (4), a differential synchronization system (6) adapted to synchronize the rotation between wheels on the same axle, wheel rotation sensors (8) adapted to measure the rotational speed of respective wheels on the vehicle and generate wheel rotation signals (10 ) depending thereon, and a detector unit (12) adapted to receive said wheel rotation signals (10) and to calculate the difference between the rotations of different wheels, compare the calculated difference with one or fl your predetermined threshold levels and generate one or fl your sliding signals (14) in dependence of the result of this comparison, characterized in that the brake control system (4) comprises a calculation unit (16) adapted to receive said one or more sliding signals (14) and signals regarding requested braking torque MB for each wheel, and that the calculation unit (16) is adapted to calculating a differential control signal (22) depending on said applied si where the calculations are adapted to be performed according to a set of control rules for said differential synchronization system (6) where the differential control signal (22) includes commands indicating the degree of synchronism between wheels on the same axle, and, if said sliding signal indicates that a wheel slides in connection with braking with the retarder braking system (2), the calculation unit (16) is adapted to calculate a currently available braking force MB for the sliding wheel according to the formula: MB = MB - Avw> <TW where Mp is the highest available braking torque for the sliding wheel; MB is the requested braking torque for the sliding wheel; Avw is a difference in rotational speed change between the sliding wheel and non-sliding wheels, and TW is the moment of inertia of the sliding wheel, and determining, with said control rules, a degree of engagement of the differential synchronizing system (6) so that the requested braking torque is achieved, the differential control signal (22) is adapted to control the engagement of the differential synchronization system (6) of the shaft with the sliding wheel in dependence thereof.
    [2]
    The vehicle of claim 1, wherein the set of control rules comprises a table with the desired transmission of torque (MB - Mp) through the 11l differential synchronization system and associated degree of engagement of the differential synchronization system.
    [3]
    The vehicle according to claim 1 or 2, wherein said sliding signal is generated if the wheel rotation speed is below a first variable threshold level, and if the difference between the rotation speeds for different wheels exceeds a second threshold level.
    [4]
    The vehicle according to any one of claims 1-3, wherein the difference in the rotational speed change Avw is calculated by the detector unit (12) between the respective braked wheel and unbraked wheels during a predetermined time interval t.
    [5]
    The vehicle according to any one of claims 1-4, wherein the calculation unit is further adapted to calculate a retarder control signal (24) and said control rules indicate the interaction between said retarder brake system (2) and differential synchronization system (6), and wherein the retarder control signal (24) comprises commands that indicates the degree of engagement of the retarder brake system (2).
    [6]
    The vehicle of claim 5 and claim 2, wherein said table of available braking force also includes the associated degree of engagement of the retarder braking system.
    [7]
    The vehicle according to any one of claims 5 and 6, wherein the calculation unit is further adapted to determine, based on the calculated current available braking force Mp for the sliding wheel, with said control rules, a degree of engagement of the retarder brake system, and the retarder control signal is adapted to control the engagement of the retarder braking system as a result.
    [8]
    The vehicle according to any one of claims 5-7, wherein said steering rules comprise increasing the synchronism between wheels on the same axle while reducing the retarding effect.
    [9]
    A method of a vehicle comprising a retarder braking system, a brake control system, a differential synchronization system adapted to synchronize the rotation between wheels on the same axle, wheel rotation sensors adapted to measure the rotational speed of respective wheels on the vehicle and generate wheel rotation signals accordingly, and a detector unit adapted to receive said wheel rotation signals and to calculate the difference between the rotations of wheels, the method comprising: - comparing the calculated difference with one or fl your predetermined threshold levels and generating a sliding signal depending on the result of this comparison, characterized in that the method further comprises: - receiving in a calculation unit one or fl your sliding signals and signals regarding the requested braking torque MB for each wheel, - calculating, if said sliding signal indicates that a wheel slides in connection with braking with the retarder braking system, a current available ig braking force Mp for the sliding wheel according to the formula: Mp = MB - Avw> <TW where Mp is the highest available braking torque for the sliding wheel; MB is the requested braking torque for the sliding wheel; Avw is a difference in rotational speed change between the sliding wheel and non-sliding wheels, and TW is the moment of inertia of the sliding wheel, and - determining, with a set of control rules, a degree of engagement of the differential synchronization system so that the required braking torque is achieved, - steering , with a differential control signal, the engagement of the differential synchronization system of the shaft with the sliding wheel depending on the determined degree of engagement.
    [10]
    The method of claim 9, wherein the set of control rules comprises a table with the desired transmission of torques (MB - Mp) through the differential synchronization system and the associated degree of engagement of the differential synchronization system.
    [11]
    The method of claim 9 or 10, wherein said sliding signal is generated if the wheel rotation speed is below a first variable threshold level, and if the difference between the rotation speeds for different wheels exceeds a second threshold level. 10 15 20 25 13
    [12]
    The method according to any one of claims 9-11, wherein the difference in the rotational speed change Avw is calculated by the detector unit between the respective braked wheel and unbraked wheel during a predetermined time interval t.
    [13]
    The method of any of claims 9 to 12, wherein the computing unit is further adapted to calculate a retarder control signal and said control rules indicating interaction between said retarder brake system and differential synchronization system, and wherein the retarder control signal includes commands indicating the degree of engagement of the retarder brake system.
    [14]
    The method of claim 13 and claim 10, wherein said table of available braking force also includes the associated degree of engagement of the retarder braking system.
    [15]
    The method according to any one of claims 13 and 14, wherein the calculation unit is further adapted to determine, based on the calculated current available braking force Mp for the sliding wheel, with said control rules, a degree of engagement of the retarder brake system, and the retarder control signal is adapted to control the engagement of the retarder braking system as a result.
    [16]
    The method of any of claims 12-14, wherein said steering rules comprise increasing the synchronism between wheels on the same axle while reducing the retarding effect.
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    同族专利:
    公开号 | 公开日
    SE536347C2|2013-09-03|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2020-09-01| NUG| Patent has lapsed|
    2020-09-29| NUG| Patent has lapsed|
    优先权:
    申请号 | 申请日 | 专利标题
    SE1250039A|SE536347C2|2012-01-23|2012-01-23|Device and method for synchronizing wheel speeds in deceleration braking|SE1250039A| SE536347C2|2012-01-23|2012-01-23|Device and method for synchronizing wheel speeds in deceleration braking|
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