Active vehicle seat suspension system

• US 5,975,508 A
• Filed: 08/11/1997
• Issued: 11/02/1999
• Est. Priority Date: 09/06/1995
• Status: Expired due to Fees

• Current Assignee: Applied Power Incorporated (ICC-Nexergy, Inc)
• Original Assignee: Applied Power Incorporated (ICC-Nexergy, Inc)
• Inventors: Beard, Andrew M.
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US08/909,298
• Time in Patent Office: 813 Days
• Field of Search: 267/131, 267/136, 267/218, 267/117, 267/64.24, 180/89.12, 180/89.14, 280/124.16, 280/124.157, 296/190.07, 296/190.01, 296/65.02, 248/550, 248/556, 188/378, 188/379, 188/380, 188/266.1, 188/266.2, 188/282.2, 188/282.3, 701/37, 701/38, 701/49
• US Class Current: 267/136
• CPC Class Codes: B60N 2/501 actively controlled suspension, e.g. electronic control
• CPC Class Codes: B60N 2/502 attached to the base of the seat B60N2/504 takes precedence
• CPC Class Codes: B60N 2/505 Adjustable suspension including height adjustment
• CPC Class Codes: B60N 2/507 Parallelogram-like structure
• CPC Class Codes: B60N 2/508 Scissors-like structure
• CPC Class Codes: B60N 2/522 characterised by dampening means
• CPC Class Codes: B60N 2/525 using gas
• CPC Class Codes: B60N 2/527 using liquids

Abstract

A seat of a vehicle is connected to the vehicle body by a support linkage that enables movement of the seat. A hydraulic actuator is connected between the seat and the vehicle body to produce motion which counteracts the influence of the vehicle body movement on the seat. An air bag, coupled between the seat and vehicle body, has a variable spring preload to compensate for differing masses placed on the seat. A motion sensor detects movement of the seat and a displacement sensor detects seat displacement. A force sensor detects a force exerted on the actuator by an operator sitting in the seat. A controller responds to the motion and displacement sensors by operating the actuator to nullify effects of the movement of the vehicle body from acting on the seat, and responds to the force sensor by varying the spring preload of the air bag to maintain the force exerted on the actuator to within a defined range.

Claims

1. An active suspension system for isolating a seat of a vehicle from motion disturbances of the vehicle body, said active suspension system comprising;

a linkage by which the seat is attached to and supported by the vehicle body in a manner that enables movement of the seat along a given axis with respect to the vehicle body;

an actuator connected between the seat and the vehicle body to produce motion of the seat which counteracts influence of the motion disturbances of the vehicle body;

a spring connected between the seat and the vehicle body and having a preload which is variable to compensate for differing masses placed on the seat;

a motion sensor detects movement of the seat along the given axis and produces a motion signal in response thereto;

a force sensor which produces a force signal indicating a magnitude of force exerted on the actuator by the seat and an operator in the seat; and

a controller which responds to the motion signal by operating the actuator to nullify effects of the motion disturbances of the vehicle body from acting on the seat, and which responds to the force signal by varying the preload of the spring to maintain the force within a predefined range.

2. The active suspension system as recited in claim 1, wherein the actuator is a hydraulic cylinder;

and a piston moveable with respect to a cylinder.

3. The active suspension system as in claim 2, wherein the force sensor senses pressure within the hydraulic cylinder.

4. The active suspension system as recited in claim 1, wherein the actuator comprises a hydraulic cylinder;

a piston; and

a first valve operable by the controller to selectively supply a pressurized fluid from a first external source to the cylinder and to selectively relieve pressurized fluid from the cylinder, causing the piston to move relative to the cylinder.

5. The active suspension system as in claim 4 wherein the force sensor senses pressure within the hydraulic cylinder.

6. The active suspension system as recited in claim 5, wherein the spring comprises an air bag;

and a second valve operable by the controller to selectively supply a pressurized gas from a second external source to the air bag and to selectively relieve pressurized gas from the air bag thereby altering preload of the spring;

wherein the controller operates the second valve to control the pressured gas in the air bag so that the pressure within the hydraulic cylinder is substantially one-half a maximum pressure of pressurized fluid available from the first external source.

7. The active suspension system as recited in claim 1, wherein the spring is an air bag and the controller varies the pressure of a gas within the air bag in response to the force signal thereby maintaining the force exerted on the actuator within a predefined range.

8. The active suspension system as recited in claim 1, wherein the spring comprises an air bag;

and a valve operable by the controller to selectively supply a pressurized gas from an external source to the air bag and to selectively relieve pressurized gas from the air bag thereby altering preload of the spring.

9. The active suspension system as recited in claim 1, wherein the linkage comprises a parallelogram suspension.

10. The active suspension system as recited in claim 9, wherein the parallelogram suspension comprises a first support member attached to the seat;

a second support member attached to the vehicle body; and

two parallel cross bars pivotally attached to both the first and second support members.

11. The active suspension system as recited in claim 1, wherein the linkage comprises two scissor mechanisms connected to the seat and to the vehicle body.

12. The active suspension system as recited in claim 1, wherein the spring is connected to the vehicle body and the linkage.

13. The active suspension system as recited in claim 1, wherein the actuator is connected to the vehicle body and the linkage.

14. The active suspension system as recited in claim 1, further comprising a displacement sensor which detects an amount of displacement of the seat with respect to the vehicle body.

15. The active suspension system as recited in claim 1, wherein the controller produces a compensated motion signal a_f according to the expression:

##EQU4## where a_S is the motion signal, and Gc is a gain factor which is a function of gains of the actuator and the motion sensor.

16. The active suspension system as recited in claim 15 wherein τ

₁ has a value of substantially 0.80 seconds and τ

₂ has a value of substantially 0.05 seconds.

17. The active suspension system as recited in claim 15:

further comprising a displacement sensor which detects an amount of displacement of the seat with respect to the vehicle body and in response produces a displacement signal; and

wherein the controller combines the compensated motion signal a_f with the displacement signal to produce an error signal which controls the operation of the first valve.

18. An active suspension system for isolating a seat of a vehicle from motion disturbances of the vehicle body, said active suspension system comprising:

a support by which the seat is connected to the vehicle body and enabling movement of the seat along a given axis with respect to the vehicle body;

a hydraulic actuator connected between the seat and the vehicle body to produce motion which counteracts influence of the motion disturbances of the vehicle body on the seat;

an air bag connected between the seat and the vehicle body and having a spring preload which is variable to compensate for differing masses placed on the seat;

a motion sensor which detects movement of the seat along the given axis and produces a motion signal in response to detected movement;

a displacement sensor which detects an amount of displacement of the seat with respect to the vehicle body

a force sensor which produces a force signal indicating a magnitude of force exerted on the actuator by the seat and an operator in the seat; and

a controller connected to the force sensor, the motion sensor and the displacement sensor, wherein the controller responds to the motion signal by operating the actuator to nullify effects of the motion disturbances of the vehicle body from acting on the seat, and responds to the force sensor by varying the spring preload of the air bag to maintain the force exerted on the actuator to within a predefined range.

19. The active suspension system as recited in claim 18 further comprising a valve operable by the controller to supply a pressurized gas from an external source to the air bag and to relieve pressurized gas from the air bag thereby altering the spring preload.

20. The active suspension system as recited in claim 18 further comprising a flow control valve operable by the controller to supply a pressurized fluid from an external source to the hydraulic actuator and relieve pressurized fluid from the hydraulic actuator thereby tending to produce movement of the seat relative to the vehicle body.

21. The active suspension system as recited in claim 18, wherein the controller produces a compensated motion signal a_f according to the expression:

##EQU5## where a_S is the motion signal, and Gc is a gain factor which is a function of gains of the actuator and the motion sensor; and

combines the compensated motion signal a_f with a signal from the displacement sensor to produce an error signal which controls the operation of the hydraulic actuator.

22. A seat assembly for a motor vehicle which nullifies motion disturbance of a vehicle body, said seat assembly comprising;

a frame;

a resilient seat cushion attached to the frame and forming a passive vibration isolator;

a support by which the frame is connected to the vehicle body and enabling movement of the frame along a given axis with respect to the vehicle body;

an active vibration isolator comprising an actuator and a spring connected between the frame and the vehicle body, wherein the actuator produces motion of the frame which counteracts influence of the motion disturbances of the vehicle body, and the spring connected has a preload which is variable to compensate for differing masses placed on the seat cushion;

a motion sensor connected to the frame to detect movement along the given axis and produce a motion signal in response to detected movement;

a force sensor which produces a force signal indicating a magnitude of force exerted on the actuator; and

a controller which responds to the motion signal by operating the actuator to nullify effects of the motion disturbances of the vehicle body from acting on the seat, and which responds to the force signal by varying the preload of the spring to maintain the force within a predefined range.

23. The seat assembly as recited in claim 22, wherein the actuator comprises a hydraulic cylinder;

a piston; and

a first valve operable by the controller to selectively supply a pressurized fluid from a first external source to the cylinder and to selectively relieve fluid from the cylinder, so as to cause the piston to move relative to the cylinder.

24. The seat assembly as in claim 23 wherein the force sensor senses pressure within the hydraulic cylinder.

25. The seat assembly as recited in claim 24, wherein the spring comprises an air bag;

and a second valve operable by the controller to selectively supply a pressurized gas from a second external source to the air bag and to selectively relieve pressurized gas from the air bag thereby altering preload of the spring;

wherein the controller operates the second valve to control the pressured gas in the air bag so that static pressure within the hydraulic cylinder is substantially one-half a maximum pressure of pressurized fluid available from the first external source.

26. The seat assembly as recited in claim 22 wherein the support comprises a parallelogram suspension.

27. The seat assembly as recited in claim 22 wherein the support comprises two scissor mechanisms connected to the frame and to the vehicle body.