Method and system for performing fail-safe operation for anti-skid automotive brake control system having a plurality of controllers independently operable to others

Claim 2

In an anti-skid brake control system for an automotive vehicle including a plurality of control systems mutually independent for controlling braking operations of respectively corresponding braking circuit, each of said control system including a pressure control valve operable among a first position in which braking pressure in the corresponding brake circuit is increased, a second position in which the braking pressure in said corresponding braking circuit is decreased and a third position in which the braking pressure in said corresponding braking circuit is held constant, an actuator associated with said pressure control valve to operate the latter according to a control signal, a wheel speed sensor producing a sensor signal indicative of rotation speed of a corresponding vehicular wheel, and a controller receiving said sensor signal for deriving said control signal on the basis thereof, a method for performing fail-safe operation when failure of operation in one of the control systems is detected, comprising the steps of: monitoring operation of each of said control systems for disabling said actuator and holding said control signal at a value indicative of said first position of said pressure control valve, and producing a fault-indicative signal, when faulty operation in the control system is detected; and monitoring operating conditions of other control system by chacking presence of said fault-indicative signal, to perform fail-safe operation to disable said actuator, to hold the control signal at a value corresponding to said first position and producing said fault-indicative signal.

Claim 3

The method as set forth in claim 1, which further comprises a step of turning on a fault warning indicator by said fault indicative signal.

Claim 4

The method as set forth in claim 1, wherein said anti-skid brake control system includes a first control system for controlling braking operation one of driven wheels, a second control system for controlling braking operation on the other of said driven wheels, and a third control system for controlling braking operation on driving wheels; and said first control system is associated with said second control system for detecting failure in said second control system, said second control system is associated with said third control system for detecting failure in said third control system, and said third control system is associated with said first control system for detecting failure in said first control system.

Claim 5

The method as set forth in claim 3, wherein said first control system is also asociated with said third control system for detecting failure ins aid third control system, said second control system is also associated with said first control system for detecting failure in said first control system, and said third control system is also associated with said second control system for detecting failure of said second control system.

Claim 6

The method as set forth in claim 2, which further comprises a step for recording data identifying faulty component in response to said fault-indicative signal.

Claim 7

A fail-safe system for an anti-skid brake control system which includes a plurality of respectively independent brake control sub-systems comprising: a plurality of hydraulic brake circuits, each cooperated corresponding one of said brake control sub-systems; a pressure control valve disposed in each of said brake circuits for increasing hydraulic brake pressure in a wheel cylinder in its first position, for decreasing hydraulic brake pressure in said wheel cylinder in its second position and for holding hydraulic brake pressure in said wheel cylinder constant in its third position; an actuator associated with each one of corresponding pressure control valve for operating said pressure control valve among said first, second and third positions according to a control signal, said actuator being connected to an electric power source to receive power supply therefrom; a sensor incorporated with each of said brake control sub-systems for detecting wheel speed and producing a second signal indicative of the wheel speed; a detector incorporated with each of said brake control sub-systems for detecting faulty operation of the components of said anti-skid brake control system and producing a fault-indicative signal when faulty operation of at least one of said components is detected; and a controller incorporated with each of said brake control sub-systems, receiving said sensor signal and processing the sensor signal, deriving values of wheel acceleration and slippage, deriving said control signal in accordance with said values, said controller being responsive to said fault-indicative signal from said detector incorporated in the corresponding sub-system to hold said control signal at a value at which said pressure control valve is in said first position and to terminate power supply to said actuator, and said cotnroller further responsive to said fault-indicative signal from said detector in other sub-system to hold said control signal at a value at which said pressure control valve is in said first position and to terminate power supply to said actuator.

Claim 8

A fail-safe system for an anti-skid brake control system which includes a plurality of respectively independent brake control sub-systems comprising: a plurality of hydraulic brake circuits, each cooperated corresponding one of said brake control sub-systems; a pressure control valve disposed in each of said brake circuits for increasing hydraulic brake pressure in a wheel cylinder in its first position, for decreasing hydraulic brake pressure in said wheel cylinder in its second position and for holding hydraulic brake pressure in said wheel cylinder constant in its third position; an actuator associated with each one of corresponding pressure control valve for operating said pressure control valve among said first, second and third positions according to a control signal, said actuator being connected to an electric power source to receive power supply therefrom; a sensor incorporated with each of said brake control sub-systems for detecting wheel speed and producing a second signal indicative of the wheel speed; a detector incorporated with each of said brake control sub-systems for detecting faulty operation of the components of said anti-skid brake control system and producing a fault-indicative signal when faulty operation of at least one of said components is detected; and a controller incorporated with each of said brake control sub-systems, receiving said sensor signal and processing the sensor signal, deriving values of wheel acceleration and slippage, deriving said control signal in accordance with said values, said controller being responsive to said fault-indicative signal from said detector incorporated in the corresponding sub-system to hold said control signal at a value at which said pressure control valve is in said first position and to terminate power supply to said actuator, and said cotnroller further responsive to said fault-indicative signal from said detector in other sub-system to hold said control signal at a value at which said pressure control valve is in said first position and to terminate power supply to said actuator.

Claim 9

The fail-safe system as set forth in claim 6, which further comprises a fault monitor lamp energized by said fault-indicative signal.

Claim 10

The fail-safe system as set forth in claim 6, which further comprises a memory associated with said detector for storing data identifying all faulty components in response to said fault-indicative signal.

Claim 11

The fail-safe system as set forth in claim 8, further comprising a faulty component indicator energized when faulty operation of a corresponding of said components is detected by said detector.

Claim 12

The fail-safe system as set forth in claim 9, wherein said detector monitors the power supply to said actuator and produces said fault-indicative signal when the power supply is interrupted.

Claim 13

ll. The fail-safe system as set forth in claim 10, wherein said detector distinguishes between termination of power supply to said actuator by said controller and by external conditions, and in the former case does not produce said fault-indicative signal.

Claim 14

The fail-safe system as set forth in claim 6, wherein said detector includes means receiving said control signal and signals indicative of the response of the components of the anti-skid control system to the current control signal comparing said control signal and said response-indicative signals and producing said fault-indicative signal when said responsive-indicative signals do not fully correspond to the response of properly functioning anti-skid control system components to the current control signal.