US 4,886,322 A · Vehicle anti-lock brake system

Abstract

The present invention concerns a vehicle anti-lock brake control system which does not require the use of an auxiliary hydraulic pump and, in the preferred embodiment, is adapted to control only the rear brakes of a four-wheel vehicle. The control system includes a normally open solenoid actuated isolation valve connected between the master cylinder and the rear wheel brakes, and a normally closed solenoid actuated dump valve connected between the rear wheel brakes and a fluid accumulator. A computer control is connected to monitor the rear wheel speed and deceleration and, during braking of the vehicle, functions to control the application of hydraulic pressure to the rear brakes via the isolation and dump valves in order to correct wheel speed departures and prevent lock-up of the brakes. The computer control is adapted to detect a low to high mu road surface change which occurs during a wheel speed departure, and thereafter applies additional pressure to the rear brakes by selectively opening the isolation valve. Further, the control is adapted to detect when one of the rear wheels remains locked after anti-lock measures have been taken. In these instances, the standard operating parameters which control the reapplication of additional pressure are modified.

Claims13

Dependent claims

In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:

a normally open isolation valve means connected between the supply means and the selected wheel brake;
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir;
and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for sensing the deceleration of the associated wheel and for detecting wheel speed departures of the associated wheel relative to the actual speed of the vehicle, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant level after a wheel speed departure of the associated wheel is detected, said control means operable to selectively open said dump valve means after said isolation valve means has been closed to enable fluid to flow into said fluid reservoir to selectively reduce pressure to the selected wheel brake and correct said wheel speed departure of the associated wheel, said control means operable to determine a reference deceleration value representing the average wheel deceleration during a cycle of said wheel speed departure, said control means further operable to reapply additional pressure to the selected brake in the event the actual average wheel deceleration over a predetermined time period following said cycle is greater than said reference deceleration value by a predetermined amount.

1 more element

In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least two selected wheel brakes to control the braking of at least two associated selected wheels, said control system comprising:

a normally open isolation valve means connected between the supply means and the selected wheel brake;
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir;
speed sensor means for generating a signal representing the average speed of the selected wheels;
and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting wheel speed departures of the selected wheels relative to the actual speed of the vehicle, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brakes at a relatively constant level after a wheel speed departure of the associated wheels is detected, said control means operable to selectively open said dump valve means after said isolation valve means has been closed to enable fluid to flow into said fluid reservoir to selectively reduce fluid pressure to the selected wheel brakes an attempt to correct said wheel speed departure, said control means responsive to a predetermined set of operating parameters for selectively opening said isolation valve means after said wheel speed departure has been corrected to selectively increase pressure to the wheel brakes, said control means including means for determining when at least one of said selected wheel brakes remains at least partially locked after the attempt to correct said wheel speed departure, said control means operable to modify said predetermined set of operating parameters in the event at least one of said selected wheel brakes remains at least partially locked.

2 more elements

In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least two selected wheel brakes to control the braking of at least two associated selected wheels, said control system comprising:

valve means connected between the supply means and the selected wheel brakes;
speed sensor means for generating a signal representing the average speed of the selected wheels;
and
control means connected to operate said valve means, said control means including means for detecting wheel speed departures of the selected wheels relative to the actual speed of the vehicle, said control means operable to actuate said valve means to selectively reduce fluid pressure to the selected wheel brakes and attempt to correct said wheel speed departure, said control means responsive to a predetermined set of operating parameters for actuating said valve means after said wheel speed departure has been corrected to selectively increase pressure to the selected wheel brakes, said control means including means for determining when at least one of said selected wheel brakes remains partially locked after the attempt to correct said wheel speed departure, said control means operable to modify said predetermined set of operating parameters in the event at least one of said selected wheel brakes remains at least partially locked.

1 more element

Dependencies are inferred from the claim text.

Vehicle anti-lock brake system

Life of this patent

Vehicle anti-lock brake system

Life of this patent

Abstract

Claims13