Active suspension system

• US 4,999,777 A
• Filed: 05/30/1989
• Issued: 03/12/1991
• Est. Priority Date: 05/28/1988
• Status: Expired due to Term

• Current Assignee: Daimler-Benz AG (Mercedes-Benz Group AG)
• Original Assignee: Daimler-Benz AG (Mercedes-Benz Group AG)
• Inventors: Schussler, Robert, Acker, Bernd
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Queen, Tyrone
• Application Number:
  US07/358,406
• Time in Patent Office: 651 Days
• Field of Search: 364/424.05, 280/707, 280/6.11, 280/703, 280/DIG. 1
• US Class Current: 701/38
• CPC Class Codes: B60G 17/016 characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input B60G17/017 takes precedence
• CPC Class Codes: B60G 2202/413 Hydraulic actuator
• CPC Class Codes: B60G 2202/414 using electrohydraulic valves
• CPC Class Codes: B60G 2204/80 Interactive suspensions; arrangement affecting more than one suspension unit
• CPC Class Codes: B60G 2400/10 Acceleration; Deceleration
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/51 in suspension unit
• CPC Class Codes: B60G 2500/20 Spring action or springs
• CPC Class Codes: B60G 2500/30 Height or ground clearance
• CPC Class Codes: B60G 2600/12 Sampling or average detecting; Addition or substraction
• CPC Class Codes: B60G 2600/182 Active control means
• CPC Class Codes: B60G 2600/20 Manual control or setting means
• CPC Class Codes: B60G 2800/012 Rolling condition
• CPC Class Codes: B60G 2800/014 Pitch; Nose dive
• CPC Class Codes: B60G 2800/246 Understeer

Abstract

Deflection detection pick-ups are arranged at the wheels or wheel suspensions of the vehicle, from the signals of which pick-ups a computer determines an averaged pitch angle. These averaged actual values are compared with predetermined or predeterminable set values. the correction of the supporting forces of the support assemblies effected thereupon by the computer is dependent on the extent to which the vehicle body has to execute pure lifting movements, pure rolling movements and/or pure pitching movements to approximate the actual values to the set values and in which proportions the forces necessary for the damping of rolling or pitching movements are to be applied by the support assemblies of the front or rear wheels. In this case, the forces serving for the compensation of rolling movements can be distributed over the front and rear wheels in such a way that a desired control tendency of the vehicle, in particular a tendency toward under-controlling, is obtained.

Claims

1. An active suspension system for a motor vehicle comprising

a computer,

actual-value pick-ups assigned to wheels of the vehicle, each of the pick-ups operatively arranged to generate a signal representative of the distance between the vehicle body and the respective wheel and feed the signal to the computer,

spring and support assemblies assigned to the wheels and operatively arranged to provide supporting forces and/or resistances counteracting the lifting movements of the wheels controlled by the computer, wherein the computer is operatively arranged to determine from the signals of the actual-value pick-ups an actual value of the averaged ground clearance, an actual value of the averaged roll angle and an actual value of the averaged pitch angle of the vehicle body and to actuate the spring and support assemblies as a function of the deviations of the actual values from set values, such that the total correction of the supporting forces and/or resistances effected by the computer has a value which corresponds essentially to the sum of those values which the computer would effect for the correction of the averages ground clearance alone and for the correction of the pitch angle alone and for the correction of the roll angle alone, and the computer is operatively arranged to actuate the supporting forces and/or resistances such that forces of the spring and support assemblies affecting rolling movements of the vehicle body can be applied by the spring and support assemblies of the front and rear wheels at predeterminable proportions to achieve a steerage tendency of the vehicle including understeering, oversteering and a neutral behavior.

2. The active suspension system according to claim 1, wherein the computer determines from each of the pick-up signals the variation over time of the actual values of the averaged ground clearance, of the averaged roll angle and of the averaged pitch angle and actuates the spring and support assemblies also as a function of the rate of change of said actual value.

3. The active suspension system according to claim 1, wherein one of the mean value of the distances of all wheels with respect to the vehicle and a value correlated with the mean value of the distances is used as the averaged ground clearance.

4. The active suspension system according to claim 1, wherein one of the difference between the means value of the distances of the front wheels from the vehicle body and the mean value of the distances of the rear wheels from the vehicle body and a value correlated with the difference are used as the averaged pitch angle.

5. The active suspension system according to claim 2, wherein one of the difference between the mean value of the distances of the front wheels from the vehicle body and the mean value of the distances of the rear wheels from the vehicle body and a value correlated with the difference are used as the averaged pitch angle.

6. The active suspension system according to claim 1, wherein one of the difference between the mean value of the distances of the right wheels from the vehicle body and the mean value of the distances of the left wheels from the vehicle body and a value correlated with the difference are used as the averaged roll angle.

7. The active suspension system according to claim 2, wherein one of the difference between the mean value of the distances of the right wheels from the vehicle body and the mean value of the distances of the left wheels from the vehicle body and a value correlated with the difference are used as the averaged roll angle.

8. The active suspension system according to claim 3, wherein one of the difference between the mean value of the distances of the right wheels from the vehicle body and the mean value of the distances of the left wheels from the vehicle body and a value correlated with the difference are used as the averaged roll angle.

9. The active suspension system according to claim 4, wherein one of the difference between the mean value of the distances of the right wheels from the vehicle body and the mean value of the distances of the left wheels from the vehicle body and a value correlated with the last-mentioned difference are used as the averaged roll angle.

10. The active suspension system according to claim 1, wherein the computer is operatively arranged to determine from the pick-up signals such wheel positions or such wheel movements which are without influence on the mean values of the ground clearance, the roll angle and/or the pitch angle and to actuate the spring and support assemblies for damping, the value of which damping depends on the movements or positions of the wheels.

11. The active suspension system according to claim 3, wherein the computer is operatively arranged to determine from the pick-up signals such wheel positions or such wheel movements which are without influence on the mean values of the ground clearance, the roll angle and/or the pitch angle and to actuate the spring and support assemblies for damping, the value of which damping depends on the movements or positions of the wheels.

12. The active suspension system according to claim 1, wherein means for detecting acceleration of the vehicle in at least one of a vertical direction, a longitudinal direction and a transverse direction are operatively arranged in the vehicle such that signals of the detecting means provide an additional stabilization of the vehicle with respect to lifting, pitching and/or rolling movements.

13. The active suspension system according to claim 1, wherein means is provided for varying distribution of the proportions of the forces of the spring and support assemblies affecting rolling movements of the vehicle body over the front and rear wheels of the vehicle as a function of lateral acceleration of the vehicle.

14. The active suspension system according to claim 13, wherein the distribution is variable so as to effect an increasing tendency towards under-controlling with increasing lateral acceleration of the vehicle.

15. The active suspension system according to claim 13, wherein means is provided for regulating the distribution of the proportions of the forces of the spring and support assemblies affecting rolling movements of the vehicle body over the front and rear wheels or a desired control tendency of the vehicle towards under-controlling.

16. The active suspension system according to claim 14, wherein means is provided for regulating the distribution of the proportions of the forces of the spring and support assemblies affecting rolling movements of the vehicle body over the front and rear wheels or a desired control tendency of the vehicle towards under-controlling.

18. The active suspension system according to claim 15, wherein the means for regulation only commences operation at a minimum value of the lateral acceleration, and the computer is operatively arranged to predetermine set values for the distribution or control tendency, which set values are dependent on the lateral acceleration and increase progressively with increasing lateral acceleration such that the set value assigned to the minimum value of the lateral acceleration coincides with the actual value determined a last time the minimum value occurred.

19. The active suspension system according to claim 18, wherein the distribution is variable so as to effect an increasing tendency towards under-controlling with increasing lateral acceleration of the vehicle.

17. The active suspension system according to claim 20, wherein means is provided for regulating the distribution of the proportions of the forces of the spring and support assemblies affecting rolling movements of the vehicle body over the front and rear wheels or a desired control tendency of the vehicle towards under-controlling.