Vehicular suspension system

• US 20050225048A1
• Filed: 03/12/2003
• Published: 10/13/2005
• Est. Priority Date: 03/12/2003
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Kasamatsu, Akira
• Granted Patent: US 7,311,314 B2
• Time in Patent Office: Days
• US Class Current: 280/124.160
• CPC Class Codes: B60G 17/0162 mainly during a motion involving steering operation, e.g. cornering, overtaking B60G17/0164 takes precedence
• CPC Class Codes: B60G 17/0185 for failure detection
• CPC Class Codes: B60G 17/056 Regulating distributors or valves for hydropneumatic systemsB60G17/044 - B60G17/048, B60G17/0416 take precedence; Fluid interconnection systems to control vehicle inclination B60G21/06, B60G21/10; valves per se F16K
• CPC Class Codes: B60G 21/055 Stabiliser bars
• CPC Class Codes: B60G 21/067 between wheels on different axles on the same side of the vehicle, i.e. the left or the right side
• CPC Class Codes: B60G 21/106 transversally
• CPC Class Codes: B60G 2600/08 Failure or malfunction detecting means
• CPC Class Codes: B60G 2800/012 Rolling condition
• CPC Class Codes: B60G 2800/80 Detection or control after a system or component failure
• CPC Class Codes: B60G 2800/9122 ARS - Anti-Roll System Control

Abstract

The object of this invention is to detect an abnormality of a roll-motion restricting device including a hydraulic circuit.

It is possible to determine that a fluid leakage takes place if actual fluid pressure in fluid passages 72, 74 connecting the corresponding fluid chambers of front-wheel-side hydraulic cylinder 30 and rear-wheel-side hydraulic cylinder 60 is lower than a value determined by a lateral acceleration value of a vehicle. On the basis of a relationship between a state of rolling of the vehicle and the fluid pressure, the hydraulic circuit can be diagnosed for any abnormality. In the event of detection of an abnormality, solenoid-operated shut-off valves 100, 102 are closed to isolate the two hydraulic cylinders 30, 60 from each other, and isolate one of the hydraulic cylinders or a portion of the fluid passage, which suffers from the fluid leakage, from the other hydraulic cylinder, so that this other hydraulic cylinder can generate a fluid pressure difference depending upon the rolling state of the vehicle, enabling a stabilizer bar to generate a resilient force, whereby the deterioration of a roll-motion restricting effect can be made smaller, than in the case where the two hydraulic cylinders are disabled to normally function.

Claims

1. A suspension system for a vehicle, characterized by comprising:

a fluid circuit including (a) at least one fluid cylinder provided on each of a front-wheel side and a rear-wheel side of the vehicle, each of said at least one fluid cylinder including a housing, and a piston which separates an interior space of the housing into two fluid chambers, said each fluid cylinder being disposed between a wheel-side member of the vehicle and a body-side member of the vehicle, such that there arises a difference between fluid pressures in said two fluid chambers when at least one of a left wheel and a right wheel is displaced in a vertical direction relative to a body of the vehicle, and (b) two fluid passage systems one of which connects one of the two fluid chambers of said at least one fluid cylinder on said front-wheel side to a corresponding one of the two fluid chambers of said at least one fluid cylinder on said rear-wheel side, and the other of which connects the other of the two fluid chambers of said at least one fluid cylinder on said front-wheel side to the other of the two fluid chambers of said at least fluid cylinder on said rear-wheel side; and

a diagnosing device operable to diagnose said fluid circuit on the basis of at least one of fluid pressures in said two fluid passage systems.

2. The suspension system according to claim 1, wherein said diagnosing device comprises (a) a roll-motion-related-quantity detecting device operable to detect a roll-motion-related quantity relating to a roll motion of the vehicle, (b) a fluid-pressure detecting device operable to detect at least one of the fluid pressures in said two fluid passage systems, and (c) an abnormality determining portion operable to determine whether said fluid circuit is abnormal, on the basis of a relationship between the fluid pressure detected by said fluid-pressure detecting device and said roll-motion-related quantity detected by said roll-motion-related-quantity detecting device.

3. The suspension system according to claim 2, wherein said roll-motion-related-quantity detecting device includes a centrifugal-force-related-quantity detecting device operable to detect a centrifugal-force-related quantity relating to a centrifugal force acting on the vehicle.

4. The suspension system according to claim 2, wherein said roll-motion-related-quantity detecting device includes a lateral-acceleration detecting device operable to detect a lateral acceleration value of the vehicle.

5. The suspension system according to claim 1, wherein said diagnosing device includes (a) a running-condition detecting device operable to detect a running condition of the vehicle, (b) a fluid-pressure detecting device operable to detect at least one of the fluid pressures in said two fluid passage systems, and (c) an abnormality determining portion operable to determine whether said fluid circuit is abnormal, on the basis of a relationship between the fluid pressure detected by said fluid-pressure detecting device and the running condition detected by said running-condition detecting device.

6. The suspension system according to claim 1, wherein said diagnosing device includes (a) a fluid-pressure detecting device operable to detect at least one of the fluid pressures in said two fluid passage systems, and (b) an abnormality determining portion operable to determine whether said fluid circuit is abnormal, on the basis of the fluid pressure detected by said fluid-pressure detecting device.

7. The suspension system according to claim 1, further comprising a fluid-circuit separating device operable to separate said fluid circuit into two parts, when said diagnosing device determines that the fluid circuit is abnormal.

8. The suspension system according to claim 1, wherein said wheel-side member is a stabilizer bar provided on each of the front-wheel and rear-wheel sides of the vehicle, and said at least one fluid cylinder on each of the front-wheel and rear-wheel sides is disposed between said stabilizer bar and said body-side member, said two fluid passage systems consisting of two fluid passages one of which connects one of the two fluid chambers of said at least one fluid cylinder on said front-wheel side to a corresponding one of the two fluid chambers of said at least one fluid cylinder on said rear-wheel side, and the other of which connects the other of the two fluid chambers of said at least one fluid cylinder on said front-wheel side to the other of the two fluid chambers of said at least one fluid cylinder on said rear-wheel side.

9. The suspension system according to claim 8, further comprising a cut-off device operable between a state for permitting fluid flows through said two fluid passages, and a state for inhibiting the fluid flows through the two fluid passages.

10. The suspension system according to claim 9, further comprising a cut-off-device control device operable to place said cut-off device in the state for inhibiting the fluid flows through said two fluid passages, when said diagnosing device has detected an abnormality of said fluid circuit.

11. The suspension system according to claim 8, wherein said two fluid passages are provided with respective accumulators, and control valves are disposed between the respective two fluid passages and the respective accumulators.

12. The suspension system according to claim 1, wherein said at least one fluid cylinder provided on each of said front-wheel and rear-wheel sides of the vehicle consists of fluid cylinders disposed for said left and right wheels, respectively, between the wheel-side member and the body-side member, and said one of said two fluid passage systems connects one of the two fluid chambers of each of the four fluid cylinders to corresponding ones of the two fluid chambers of the other of the four fluid cylinders, while said other of the two fluid passage systems connects the other of the two fluid chambers of said each of the four fluid cylinders to the other of said other of the four fluid cylinders.

13. The suspension system according to claim 12, further comprising an emergency cut-off device operable to isolate a first fluid circuit and a second fluid circuit from each other, when an abnormality of said fluid circuit is detected by said diagnosing device, said first fluid circuit including the two fluid cylinders respectively provided for one of front and rear wheels located on a right side of the vehicle and one of front and rear wheels located on a left side of the vehicle, while said second fluid circuit including the other two fluid cylinders.

14. The suspension system according to claim 13, wherein each of said two fluid passage systems includes a first fluid passage connecting the corresponding fluid chambers of said two fluid cylinders, a second fluid passage connecting the corresponding fluid chambers of the other two fluid cylinders, and a third fluid passage connecting said first and second fluid passages, and said emergency cut-off device includes a fluid-passage cut-off device operable to inhibit fluid flows through said third fluid passage.

15. The suspension system according to claim 1, wherein said fluid circuit includes (a) a connecting passage connecting said two fluid passage systems to each other, and (b) a communication control valve provided in said connecting passage, said suspension system further comprising a communication-control-valve control device operable to control said communication control valve on the basis of a running condition of the vehicle.

16. The suspension system according to claim 15, wherein said communication-control-valve control device includes a fluid-pressure control portion operable to control said communication control valve for controlling a fluid pressure in each of said two fluid chambers of said at least one fluid cylinder such that said two fluid chambers do not provide an effect of restricting a roll motion of the vehicle, while the vehicle is running straight.

20. The suspension system according to claim 1, wherein said each of said at least one fluid cylinder has two piston rods extending from said piston in respective opposite directions, and one of said two piston rods is held in engagement with said wheel-side member.

17. A suspension system for a vehicle, characterized by comprising:

a fluid circuit including (a) at least one fluid cylinder provided on each of a front-wheel side and a rear-wheel side of the vehicle, each of said at least one fluid cylinder including a housing, and a piston which separates an interior space of the housing into two fluid chambers, said each fluid cylinder being disposed between a wheel-side member of the vehicle and a body-side member of the vehicle, such that there arises a difference between fluid pressures in said two fluid chambers when at least one of a left wheel and a right wheel is displaced in a vertical direction relative to a body of the vehicle, and (b) two fluid passage systems one of which connects one of the two fluid chambers of said at least one fluid cylinder on said front-wheel side to a corresponding one of the two fluid chambers of said at least one fluid cylinder on said rear-wheel side, and the other of which connects the other of the two fluid chambers of said at least one fluid cylinder on said front-wheel side to the other of the two fluid chambers of said at least one fluid cylinder on said rear-wheel side;

a separating device operable to separate said fluid circuit into two parts; and

a separating-device control device operable to control said separating device on the basis of at least one of fluid pressures in said two fluid passage systems.

18. The suspension system according to claim 17, wherein said separating-device control device includes (a) a fluid-pressure detecting device operable to detect at least one of the fluid pressure in said two fluid passage systems, and (b) a separating-device control portion operable to control said separating device on the basis of the at least one of the fluid pressures detected by said fluid-pressure detecting device.

19. The suspension system according to claim 17, wherein said separating-device control device includes (c) a roll-motion-related-quantity detecting device operable to detect a roll-motion-related quantity relating to a roll motion of the vehicle, and (d) a roll-motion-dependent control portion operable to control said separating device on the basis of a relationship between the roll-motion-related quantity detected by said roll-motion-related-quantity detecting device and at least one of the fluid pressures in said two fluid passage systems.

21. The suspension system according to claim 17, wherein said each of said at least one fluid cylinder has two piston rods extending from said piston in respective opposite directions, and one of said two piston rods is held in engagement with said wheel-side member.