Stability control device of vehicle adaptive to failure of wheel speed sensor

• US 5,707,119 A
• Filed: 10/04/1996
• Issued: 01/13/1998
• Est. Priority Date: 10/19/1995
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Monzaki, Shirou
• Primary Examiner(s): Ballato, Josie
• Application Number:
  US08/725,469
• Time in Patent Office: 466 Days
• Field of Search: 303/122.05, 303/122.06, 303/140, 303/146, 303/147, 303/169, 303/DIG. 6, 364/426.016, 364/426.021
• US Class Current: 303/146
• CPC Class Codes: B60T 2210/22 Banked curves
• CPC Class Codes: B60T 2270/402 Back-up
• CPC Class Codes: B60T 2270/416 Wheel speed sensor failure
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60T 8/246 Change of direction
• CPC Class Codes: B60T 8/4836 wherein a booster output pressure is used for normal or anti lock braking B60T8/4845, B60T8/4863, B60T8/489 take precedence
• CPC Class Codes: B60T 8/885 using electrical circuitry

Abstract

A stability control device of a vehicle having an estimator for identifying a tendency of the vehicle body toward running instability when, for example, the vehicle is making a turn, and for producing an instability quantity which generally increases along with increase of the tendency; a first wheel speed detector of an inside wheel, with respect to the duration of turn, for producing an inside wheel speed signal; a second wheel speed detector of an outside wheel for producing an outside wheel speed signal; a brake for selectively applying a variable braking force to each of the wheels; and a controller for controlling the brake so as variably to apply a braking force to the outside wheel according to calculations based upon the instability quantity and the inside wheel speed signal, wherein the controller uses the outside wheel speed signal as a substitute for the inside wheel speed signal when the inside wheel speed signal is judged to be abnormal, and further, when the outside wheel speed signal is judged to be abnormal, the controller holds the braking force applied to the outside wheel constant for a predetermined period before terminating the control operation.

Claims

1. A stability control device of a vehicle having a vehicle body, and front left, front right, rear left and rear right wheels, comprising:

means for estimating a tendency of the vehicle body toward a running instability to produce an instability quantity which generally increases along with increase of said tendency;

means for detecting wheel speed of a first one of said wheels serving at the leftside of the vehicle to produce a first wheel speed signal;

means for detecting wheel speed of a second one of said wheels serving at the rightside of the vehicle to produce a second wheel speed signal;

brake means for selectively applying a variable braking force to each of said wheels; and

control means for controlling said brake means so as to selectively variably apply a braking force to either said first wheel or said second wheel according to calculation thereof based upon said instability quantity and either said second wheel speed signal or said first wheel speed signal according to whether said first wheel or said second wheel is applied with the braking respectively, in order to suppress the running instability of the vehicle body,

wherein said control means uses either said first wheel speed signal or said second wheel speed signal as a substitute for either said second wheel speed signal or said first wheel speed signal, respectively, when said second wheel speed signal or said first wheel speed signal upon which said calculation is to be based is determined to be abnormal.

2. The stability control device according to claim 1, wherein said control means terminates the control operation when the determination of said second wheel speed signal or said first wheel speed signal as being abnormal has continued for a predetermined period.

3. A stability control device of a vehicle having a vehicle body, and front left, front right, rear left and rear right wheels, comprising:

means for estimating a tendency of the vehicle body toward a running instability to produce an instability quantity which generally increases along with increase of said tendency;

means for detecting wheel speed of a first one of said wheel serving at the leftside of the vehicle to produce a first wheel speed signal;

means for detecting wheel speed of a second one of said wheels serving at the rightside of the vehicle to produce a second wheel speed signal;

brake means for selectively applying a variable braking force to each of said wheels; and

control means for controlling said brake means so as to selectively variably apply a braking force to either said first wheel or said second wheel according to calculation thereof based upon said instability quantity and either said second wheel speed signal or said first wheel speed signal according to whether said first wheel or said second wheel is applied with the braking, respectively, for suppressing the running instability of the vehicle body,

wherein, when said first wheel speed signal or said second wheel speed signal is judged to be abnormal, said control means holds the braking force applied to said first wheel or said second wheel constant for a predetermined period before terminating the control operation thereof.

4. A stability control device for a vehicle having left front, right front, left rear and right rear wheels, comprising:

a wheel speed sensor associated with each wheel and outputting a wheel speed signal;

means for estimating a tendency of the vehicle to become unstable during a turn;

a brake system including components for individually controlling the braking applied to each wheel;

control means for applying a braking force through the brake system to at least a front outside wheel when the vehicle is turning on a basis of an estimate of a tendency of the vehicle to become unstable and the wheel speed signal of the wheel sensor for a front wheel at an inside of the turn, wherein when an abnormal operation of the wheel sensor of the wheel at the inside of the turn occurs, the wheel speed signal from the wheel speed sensor of a front wheel at the outside of the turn is used as a substitute for the wheel speed signal by the control means.

5. The stability control device according to claim 4, wherein the control means terminates stability control when an abnormal signal from the wheel speed sensor of at least one of the front wheel at the inside of the turn and the front wheel at the outside of the turn has been abnormal for greater than a predetermined period of time.

6. The stability control device according to claim 4, wherein when at least the wheel speed signal from the wheel speed sensor of the wheel at the outside of the turn is abnormal, the control means maintains the braking force currently applied to the wheel at the outside of the turn for a predetermined period of time and then terminates control.