US 5,513,108 AGranted

System for controlling suspension in accordance with road conditions

AssigneeMitsubishi Jidosha Kogyo Kabushiki Kaisha

InventorsNaohiro Kishimoto, Hiroaki Yoshida, Kiichi Yamada

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Abstract

A suspension system includes air suspensions provided for individual wheels of a motor vehicle, each including a damping force switching actuator and an air supply/discharge actuator for the air spring. It further includes sensor for detecting the steering angle of a steering wheel, a sensor for detecting the vehicle velocity, and a control device for controlling the damping force and spring constant of each air suspension in accordance with the values detected by means of the sensors. This thereby reduces the roll of the vehicle body and modifies the steering characteristic of the motor vehicle. The control device includes a controller for detecting the gradient and flexure degree of a road. It further includes a controller for discriminating the road conditions by fuzzy inference in accordance with the gradient and flexure degree, and for determining the delay time or time interval between the start of the roll control for the rear portion of the vehicle body and the start of the roll control for the front portion of the vehicle body in accordance with the result of the discrimination.

Claims24

Dependent claims

A suspension control system of a motor vehicle running on a road, said motor vehicle having a vehicle body, front wheels, and rear wheels, said system comprising:

suspensions for connecting the vehicle body with the wheels, including a front group of front-wheel suspensions providing a front roll stiffness on the front side of the vehicle body, and a rear group of rear-wheel suspensions providing a rear roll stiffness on the rear side of the vehicle body;
detecting means for detecting movement states of the vehicle body and outputting respective detection signals;
first output means for calculating a total roll stiffness of the whole vehicle body in response to the detection signals from the detecting means and delivering a first control signal, indicative of required front and rear roll stiffnesses in accordance with a result of the calculation of the first output means;
arithmetic means for calculating a first state variable indicative of a flexure degree of the road and a second state variable indicative of a gradient of the road in accordance with the detection signals from the detecting means and outputting the results of the calculation of the arithmetic means;
second output means for delivering a second control signal to the control means in accordance with the calculation results from the arithmetic means to vary the front and rear roll stiffnesses, thereby modifying a steering characteristic of the motor vehicle;
and
control means for independently controlling the front and rear roll stiffnesses provided by the front and rear groups of suspensions in accordance with the first control signal and the second control signal.

4 more elements

A method for controlling suspensions of a motor vehicle traveling on a road, the motor vehicle including a vehicle body, front wheels, and rear wheels, the suspensions connecting the vehicle body with the wheels and including a front group of front wheel suspensions providing a front roll stiffness on the front side of the vehicle body and a rear group of rear-wheel suspensions providing a rear roll stiffness on the rear side of the vehicle body, the method comprising the steps of:

(a) detecting movement states of the vehicle body and outputting respective detection signals;
(b) calculating a total roll stiffness of the whole vehicle body in response to the output detection signals;
(c) outputting a first control signal indicative of required front and rear roll stillnesses in accordance with the calculation of step (b);
(d) calculating a first state variable, indicative of a flexure degree of the road, in accordance with the detection signals;
(e) calculating a second state variable, indicative of a gradient of the road, in accordance with the detection signals;
(f) outputting a second control signal, in accordance with the calculations of steps (d) and (e), to vary the front and rear roll stiffnesses, thereby modifying a steering characteristic of the motor vehicle;
and
(g) controlling, independently, the front and rear roll stiffnesses provided by the front and rear groups of suspensions in accordance with the output first control signal and the output second control signal.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/016,978Filed 12 Feb 1993
Priority: JP 4-02839814 Feb 1992
Granted: 30 Apr 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification19 codes

B60G 21/073
Fluid: between wheels on the same axle but on different sides of the vehicle, i.e. the left and right wheel suspensions being interconnected
B60G 17/0162
Characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input: mainly during a…
B60G 17/0182
Characterised by the use of a specific signal treatment or control method: involving parameter estimation, e.g. observer, Kalman filter
B60G 2400/104
Acceleration; Deceleration: lateral or transversal with regard to vehicle