Suspension control apparatus

Patent metadata

Field	Value
Publication number	US-9278599-B2
Application number	US-201314037914-A
Country	US
Kind code	B2
Filing date	Sep 26, 2013
Priority date	Sep 28, 2012
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

A suspension control apparatus includes a damping force adjustable shock absorber disposed between a vehicle body and a wheel of a vehicle and capable of adjusting a damping force to be generated, a vertical movement detection device configured to detect a state regarding a vertical movement of a vehicle, and a controller including: a target damping force calculation section configured to calculate a target damping force based on a detection result of the vertical movement detection device, a correction section configured to calculate a corrected damping force, which is acquired by reducing the target damping force when a relative speed is a low speed between a sprung side and an unsprung side of the damping force adjustable shock absorber, and a control signal output section configured to output the control signal corresponding to the corrected damping force to the damping force adjustable shock absorber.

First claim

What is claimed is:

1. A suspension control apparatus comprising:
a damping force adjustable shock absorber disposed between a sprung side and an unsprung side of a vehicle and capable of adjusting a damping force to be generated;
a vertical movement detection device configured to detect a state regarding a vertical movement of the vehicle; and
a controller configured to output a control signal for controlling the damping force to be generated by the damping force adjustable shock absorber based on a detection result of the vertical movement detection device,
wherein the controller is configured to:
calculate a target damping force based on a detection result of the vertical movement detection device,
calculate a corrected damping force, which is smaller than an absolute value of the target damping force, when a relative speed between the sprung side and the unsprung side of the vehicle is a low speed, an absolute value of the corrected damping force increasing as the relative speed increases, an inclination of the corrected damping force to the relative speed being smaller when the relative speed is in a first speed region, the inclination of the corrected damping force to the relative speed being larger than in the first speed region when the relative speed is in a second speed region higher than the first speed region, and
output the control signal corresponding to the corrected damping force to the damping force adjustable shock absorber, when the absolute value of the calculated corrected damping force is smaller than the absolute value of the calculated target damping force.

2. The suspension control apparatus according to claim 1 , further comprising an orientation change detection device configured to detect an orientation change of a vehicle body of the vehicle,
wherein the controller sets a smaller amount as a correction amount to reduce the target damping force when it is determined that the orientation change occurs based on a detection result of the orientation change detection device.

3. The suspension control apparatus according to claim 1 , wherein the controller reduces the target damping force only at a departure from stroke reversion between an extension stroke and a compression stroke of the damping force adjustable shock absorber.

4. The suspension control apparatus according to claim 1 , wherein the controller determines whether the relative speed is a low speed based on a change rate of the relative speed or a change rate of a change rate of the relative speed.

5. The suspension control apparatus according to claim 1 , wherein the controller sets the corrected damping force so as to be smaller than a damping force that the damping force adjustable shock absorber can generate.

6. A suspension control apparatus comprising:
a damping force adjustable shock absorber disposed between a sprung side and an unsprung side of a vehicle and capable of adjusting a damping force to be generated;
a vertical movement detection device configured to detect a state regarding a vertical movement of the vehicle; and
a controller configured to output a control signal for controlling a damping force to be generated by the damping force adjustable shock absorber based on a detection result of the vertical movement detection device,
wherein the controller is configured to:
calculate a target damping coefficient based on a detection result of the vertical movement detection device,
calculate a corrected damping coefficient, which is acquired by reducing an upper limit of the target damping coefficient, when a relative speed between the sprung side and the unsprung side of the vehicle is a low speed, the corrected damping coefficient being smaller when the relative speed is in a first speed region, the corrected damping coefficient being larger than in the first speed region when the relative speed is in a second speed region higher than the first speed region, and
output the control signal corresponding to the corrected damping coefficient to the damping force adjustable shock absorber, when the calculated corrected damping coefficient is smaller than the calculated target damping coefficient.

7. The suspension control apparatus according to claim 6 , wherein the controller compares the target damping coefficient with the corrected damping coefficient and outputs the control signal based on a smaller one of the target damping coefficient and the corrected damping coefficient.

8. The suspension control apparatus according to claim 6 , wherein the controller uses bilinear optimal control.

9. The suspension control apparatus according to claim 6 , wherein the controller outputs the control signal corresponding to the target damping coefficient to the damping force adjustable shock absorber, when the calculated target damping coefficient is smaller than the calculated corrected damping coefficient.

10. The suspension control apparatus according to claim 6 , further comprising an orientation change detection device configured to detect an orientation change of a vehicle body of the vehicle,
wherein the controller sets a smaller amount as a correction amount to reduce the target damping coefficient when it is determined that the orientation change occurs based on a detection result of the orientation change detection device.

11. The suspension control apparatus according to claim 6 , wherein the controller reduces the target damping coefficient only at a departure from stroke reversion between an extension stroke and a compression stroke of the damping force adjustable shock absorber.

12. The suspension control apparatus according to claim 6 , wherein the controller determines whether the relative speed is a low speed based on a change rate of the relative speed or a change rate of a change rate of the relative speed.

13. The suspension control apparatus according to claim 6 , wherein the controller sets the corrected damping coefficient so as to be smaller than a damping coefficient that the damping force adjustable shock absorber can generate.

14. The suspension control apparatus according to claim 6 , wherein the corrected damping coefficients in the first speed region and the second speed region are constant values, and between the first speed region and the second speed region the corrected damping coefficient increases as the relative speed increases.

15. The suspension control apparatus according to claim 6 , wherein the damping coefficient at the first speed region is larger than zero.

16. The suspension control apparatus according to claim 1 , wherein the controller compares the target damping force with the corrected damping force and outputs the control signal based on a smaller one of the target damping force and the corrected damping force.

17. The suspension control apparatus according to claim 1 , wherein the controller outputs the control signal corresponding to the target damping force to the damping force adjustable shock absorber, when an absolute value of the calculated target damping force is smaller than an absolute value of the calculated corrected damping force.

18. The suspension control apparatus according to claim 1 , wherein the controller uses bilinear optimal control.

19. The suspension control apparatus according to claim 1 , wherein the corrected damping force is set to zero when the relative speed is zero.

Assignees

• Hitachi Automotive Systems Ltd
• Hitachi Automative Systems Ltd

Inventors

• Hirao Ryusuke

Classifications

• B60G2400/102

  vertical · CPC title

• B60G17/016 Primary

  characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input {(B60G17/017 takes precedence)} · CPC title

• B60G2500/10

  Damping action or damper · CPC title

• B60G21/00

  Interconnection systems for two or more resiliently-suspended wheels, e.g. for stabilising a vehicle body with respect to acceleration, deceleration or centrifugal forces (B60G17/033 takes precedence {; levelling or stabilising systems for tippers B60P1/045}; steering deflectable wheels combined with means for inwardly inclining the vehicle body on bends B62D9/02) · CPC title

• B60G2400/25

  Stroke; Height; Displacement · CPC title