Apparatus for adjusting vehicle body height

• US 5,141,245 A
• Filed: 06/11/1991
• Issued: 08/25/1992
• Est. Priority Date: 10/14/1988
• Status: Expired due to Fees

• Current Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Hiwatashi, Yutaka, Mine, Atsushi, Kamimura, Katsuyoshi
• Primary Examiner(s): Marmor, Charles A.
• Assistant Examiner(s): FERRITER, KARIN L
• Application Number:
  US07/713,593
• Time in Patent Office: 441 Days
• Field of Search: 280/707, 280/DIG. 1, 280/840, 280/6.12, 280/703, 364/424.05
• US Class Current: 280/5.514
• 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 2202/15 Fluid spring
• CPC Class Codes: B60G 2202/152 Pneumatic spring
• CPC Class Codes: B60G 2204/80 Interactive suspensions; arrangement affecting more than one suspension unit
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2500/30 Height or ground clearance
• CPC Class Codes: B60G 2600/18 Automatic control means
• CPC Class Codes: B60G 2600/20 Manual control or setting means
• CPC Class Codes: B60G 2600/85 Speed of regulation

Abstract

An apparatus for adjusting a body height of a vehicle by supplying or discharging air into or from an air suspension system includes a controller for controlling a vertical vehicle body height to a predetermined set value responsive to a signal according to an adjustment amount of the vehicle body height obtained by subtracting an objective reference vehicle body height signal from a relative displacement signal. The apparatus further includes vehicle body height change control means connected to the controller for variably controlling a vehicle body height adjustment completion time and a vehicle body height adjusting speed responsive to the vehicle speed. The vehicle body height change control means comprises a sensor for detecting the vehicle speed and generating a signal according to the vehicle speed and a logic circuit for variably controlling the vehicle body height adjusting time and the vehicle body height adjusting speed such that when the vehicle speed signal indicates a high value, the vehicle body height adjusting time is lengthened or the vehicle body height adjusting speed is lowered and when the vehicle speed signal indicates a low value, the vehicle body height adjusting time is shortened or the vehicle body height adjusting speed is increased.

Claims

1. An apparatus for adjusting a vehicle body height by controlling fluid in a suspension system provided for a wheel of a vehicle, comprising:

a speed sensor provided to detect vehicle speed;

a displacement sensor connected to the suspension system for detecting a vertical relative displacement of a vehicle body;

regulating means connected to the suspension system for regulating an amount of the fluid to the suspension system;

a switch provided to change an objective reference vehicle body height;

setting means for variably setting a vehicle body height adjusting time in response to said vehicle speed;

first calculating means for calculating a present reference vehicle body height defined by a function in which a reference vehicle body height is gradually changed to the objective reference vehicle body height from a value of the reference vehicle body height at the time when the objective reference vehicle body height is changed by said switch, while said vehicle body height adjusting time elapses; and

second calculating means for calculating a difference between the present reference vehicle body height and the vertical relative displacement so as to control said regulating means such that said difference becomes zero, thereby gradually changing the vehicle body height to said objective reference vehicle body height within said vehicle body height adjusting time when said objective reference vehicle body height is changed by said switch.

2. The apparatus according to claim 1, wherein;

said regulating means comprises an air flow regulator including an air supply valve and an air discharge valve.

3. The apparatus according to claim 1, wherein

said first calculating means has said function which is a linearly increasing function.

4. The apparatus according to claim 1, wherein

said first calculating means has said function which is a secondary increasing function.

5. The apparatus according to claim 1, wherein

said first calculating means has said function which is a trigonometric increasing function.

6. An apparatus for adjusting a vehicle body height by controlling fluid in a suspension system provided for a wheel of a vehicle, comprising:

a speed sensor provided to detect vehicle speed;

a displacement sensor connected to the suspension system for detecting a vertical relative displacement of a vehicle body;

regulating means connected to the suspension system or regulating an amount of the fluid to the suspension system;

a switch provided to change an objective reference vehicle body height;

setting means for variably setting a vehicle body height adjusting speed in response to said vehicle speed;

first calculating means for calculating a present reference vehicle body height defined by a function in which a reference vehicle body height is gradually changed, upon said vehicle body height adjusting speed, to the objective reference vehicle body height from a value of the reference vehicle body height at the time when the objective reference vehicle body height is changed by said switch; and

second calculating means for calculating a difference between the present reference vehicle body height and the vertical relative displacement so as to control said regulating means such that said difference becomes zero, thereby gradually changing the vehicle body height to said objective reference vehicle body height when said objective reference vehicle body height is changed by said switch.

7. The apparatus according to claim 6, wherein

said first calculating means has said function which is a linearly increasing function.

8. The apparatus according to claim 6, wherein

said first calculating means has said function which is a secondary increasing function.

9. The apparatus according to claim 6, wherein

said first calculating means has said function which is a trigonometric increasing function.

10. The apparatus according to claim 6, wherein

said regulating means comprises an air flow regulator including an air supply valve and an air discharge valve.

11. A method for adjusting a vehicle body height by controlling fluid in a suspension system provided for a wheel of a vehicle having a vehicle speed sensor, a displacement sensor, regulating means, a switch and control means, said method comprising the steps of:

detecting the vehicle speed by the vehicle speed sensor;

detecting a vertical relative displacement of a vehicle body by the displacement sensor;

regulating an amount of the fluid to the suspension system by the regulating means;

changing an objective reference vehicle body height by the switch;

setting a vehicle body height adjusting speed in response to the vehicle speed;

calculating a present reference vehicle body height defined by a function in which a present reference vehicle body height is changed, upon said vehicle body height adjusting speed, to the objective reference vehicle height from a value of the reference vehicle body height at a time when the objective reference vehicle body height is changed by the switch;

calculating a difference between the present reference vehicle body height and the vertical relative displacement; and

controlling the regulating means in accordance with said difference, thereby gradually changing the vehicle body height to the objective reference vehicle body height when the objective reference vehicle body height is changed by the

12. The method according to claim 11, wherein said function is a linearly increasing function.

13. The method according to claim 11, wherein said function is a secondary increasing function.

14. The method according to claim 11, wherein said function is a trigonometric increasing function.

15. The method according to claim 11, wherein said function is a stepwisely increasing function.

16. A method for adjusting a vehicle body height by controlling fluid in a suspension system provided for a wheel of a vehicle having a vehicle speed sensor, a displacement sensor, regulating means, a switch and control means, said method comprising the steps of:

detecting the vehicle speed by the vehicle speed sensor;

detecting a vertical relative displacement of a vehicle body by the displacement sensor;

regulating an amount of the fluid to the suspension system by the regulating means;

changing an objective reference vehicle body height by the switch;

setting a vehicle body height adjusting time in response to the vehicle speed;

calculating a present reference vehicle body height defined by a function in which a present reference vehicle body height is changed to the objective reference vehicle height from a value of the reference vehicle body height at a time when the objective reference vehicle body height is changed by the switch, while said vehicle body height adjusting time has elapses;

calculating a difference between the present reference vehicle body height and the vertical relative displacement; and

controlling the regulating means in accordance with said difference, thereby gradually changing the vehicle body height to the objective reference vehicle body height when the objective reference vehicle body height is changed by the switch.

17. The method according to claim 16, wherein said function is linearly increasing function.

18. The method according to claim 16 wherein said function is a secondary increasing function.

19. The method according to claim 16, wherein said function is a trigonometric increasing function.

20. The method according to claim 16, wherein said function is a stepwisely increasing function.