Suspension controller

• US 5,257,814 A
• Filed: 12/19/1991
• Issued: 11/02/1993
• Est. Priority Date: 12/20/1990
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Tokico Limited (Hitachi, Ltd.)
• Inventors: Kohara, Takao
• Primary Examiner(s): Rice, Kenneth R.
• Application Number:
  US07/810,293
• Time in Patent Office: 684 Days
• Field of Search: 280/787, 280/772, 280/711, 280/714, 280/DIG. 1
• US Class Current: 280/5.508
• 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 2204/82 left and right unit on same axle
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/41 Steering angle
• CPC Class Codes: B60G 2400/50 Pressure
• CPC Class Codes: B60G 2500/30 Height or ground clearance
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/14 Differentiating means, i.e. differential control
• CPC Class Codes: B60G 2600/90 other signal treatment means
• CPC Class Codes: B60G 2800/012 Rolling condition
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: Y10S 280/01 Load responsive, leveling of vehicle

Abstract

A suspension controller includes a controller that actuates devices for charging and discharging a pressure fluid into and from front and rear wheel-side cylinders. The controller has first-order lag circuits including first-order lag elements with different time constants. In the early stage of a steering operation, the rear wheel-side cylinders carry a higher travelling load than that shared by the front wheel-side cylinders on the basis of transverse acceleration data detected with a transverse acceleration sensor, so that excellent vehicle turning characteristics can be obtained. After a predetermined time has elapsed, the front wheel-side cylinders are also subjected to control based on the transverse acceleration data, so that the load is shared between the front and rear wheel-side cylinders in a well-balanced manner. Thus, excellent convergence is obtained.

Claims

1. A suspension controller of a vehicle having a vehicle body and front and rear wheels, said controller comprising:

level-control cylinders each associated with a respective one of the front and rear wheels of the vehicle, and each of the level-control cylinders being interposed between the vehicle body and a member provided on the respective one of the front and rear wheels in such a manner that the level of the vehicle is established by the amount of pressurized fluid in the cylinders;

front wheel-side charging and discharging means for selectively charging and discharging pressurized fluid into and from each said level-control cylinder associated with a respective front wheel of the vehicle;

rear wheel-side charging and discharging means for selectively charging and discharging pressurized fluid into and from each said level-control cylinder associated with a respective rear wheel of the vehicle;

transverse acceleration detecting means for detecting transverse acceleration acting on the vehicle while the vehicle is making a turn and for outputting a transverse acceleration signal representative of the transverse acceleration; and

control means, operatively connected to said transverse acceleration detecting means and to said front and said rear wheel-side charging and discharging means, for receiving said transverse acceleration signal, for generating first and second control signals based on said transverse acceleration signal, for inputting said second control signal to the rear wheel-side charging and discharging means, and for inputting said first control signal to said front wheel-side charging and discharging means after the second control signal has been input to said rear wheel-side charging and discharging means such that each said level-control cylinder associated with a rear wheel of the vehicle is controlled by said rear wheel-side charging and discharging means on the basis of the transverse acceleration acting on the vehicle in advance of each said level-control cylinder associated with a front wheel of the vehicle being controlled by said front wheel-side charging and discharging means on the basis of the transverse acceleration.

2. A suspension controller according to claim 1, wherein said control means includes a first lag circuit which creates a time delay between when the transverse acceleration signal is received by the control means and said first control signal is output by the control means.

3. A suspension controller according to claim 2, wherein said control means includes a second lag circuit which creates a time delay between when the transverse acceleration signal is received by the control means and said second control signal is output by the control means, the time delay created by said first lag circuit being of a greater duration than the time delay created by said second lag circuit.

4. A suspension controller according to claim 2, wherein the time delay has the characteristics of a first-order lag.

5. A suspension controller according to claim 3, wherein the time delay created by said first and said second lag circuits each have the characteristics of a first-order lag.

6. A suspension controller of a vehicle having a vehicle body and front and rear wheels, said controller comprising:

fluid-accommodating chambers each associated with a respective one of the front and rear wheels of the vehicle, and each of the fluid-accommodating chambers being interposed between the vehicle body and a member provided on the respective one of the front and rear wheels in such a manner that the level of the vehicle is established by the amount of pressurized fluid in the chambers;

front wheel-side charging and discharging means for selectively charging and discharging pressurized fluid into and from each said fluid-accommodating chamber associated with a respective front wheel of the vehicle;

rear wheel-side charging and discharge means for selectively charging and discharging pressurized fluid into and from each said fluid-accommodating chamber associated with a respective rear wheel of the vehicle;

transverse acceleration detecting means for detecting transverse acceleration acting on the vehicle while the vehicle is making a turn and for outputting a transverse acceleration signal representative of the transverse acceleration; and

control means, operatively connected to said transverse acceleration detecting means and to said front and said rear wheel-side charging and discharging means, for receiving said transverse acceleration signal, for generating first and second control signals based on said transverse acceleration signal, for inputting said second control signal to the rear wheel-side charging and discharging means, and for inputting said first control signal to said front wheel-side charging and discharging means after the second control signal has been input to said rear wheel-side charging and discharging means such that each said fluid-accommodating chamber associated with a rear wheel of the vehicle is acted on by said rear wheel-side charging and discharging means on the basis of the transverse acceleration acting on the vehicle in advance of each said fluid-accommodating chamber associated with a front wheel of the vehicle being acted on by said front wheel-side charging and discharging means on the basis of the transverse acceleration.

7. A suspension controller according to claim 6, wherein said control means includes a first lag circuit which creates a time delay between when the transverse acceleration signal is received by the control means and said first control signal is output by the control means.

8. A suspension controller according to claim 7, wherein said control means includes a second lag circuit which creates a time delay between when the transverse acceleration signal is received by the control means and said second control signal is output by the control means, the time delay created by said first lag circuit being of a greater duration than the time delay created by said second lag circuit.

9. A suspension controller according to claim 7, wherein the time delay has the characteristics of a first-order lag.

10. A suspension controller according to claim 8, wherein the time delay created by said first and said second lag circuits each have the characteristics of a first-order lag.