Anti-skid brake control system with fail-safe system responsive to abnormal power supply

• US 5,129,713 A
• Filed: 05/14/1984
• Issued: 07/14/1992
• Est. Priority Date: 05/17/1983
• Status: Expired due to Term

• Current Assignee: Nissan Motor Company Limited 2 Takara-Cho Kanagawa-Ku Yokohama-Shi Kanagawa-Ken Japan
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Matsuda, Toshiro
• Primary Examiner(s): Oberley, Alvin E.
• Application Number:
  US06/610,005
• Time in Patent Office: 2,983 Days
• Field of Search: 303/92, 303/20, 303/116, 303/119, 340/52 R, 340/52 B, 340/636, 188/181 C, 188/181 A
• US Class Current: 303/122.05
• CPC Class Codes: B60T 2270/414 Power supply failure
• CPC Class Codes: B60T 8/88 with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means
• CPC Class Codes: B60T 8/885 using electrical circuitry

Abstract

A fail-safe system for an anti-skid brake control system includes a switch disposed within a power supply circuit of the anti-skid brake control system for connecting and disconnecting a vehicle battery to the anti-skid control system. A battery voltage monitor produces a disabling signal when the battery voltage drops below a predetermined battery voltage threshold. A gating circuit is disposed between the battery voltage monitor and the anti-skid control system to selectably transmit the disabling signal to the latter. The gating circuit receives as input the output of the anti-skid brake control system, and thus responds to operation of the anti-skid control system by blocking transmission of the disabling signal. Thus, the gating circuit allows the disabling signal to be transmitted to the anti-skid control system only while the anti-skid control system is inoperative. The switch disconnects the battery from the anti-skid control system in response to the disabling signal.

Claims

1. A fail-safe system for an anti-skid automotive brake control system comprising:

a battery for supplying electric power to said anti-ski control system;

a switch means disposed between said battery and said anti-skid control system, said switch means being operative between a first normal position for connecting said battery to said anti-skid control system and a second position for disconnecting the battery from said anti-skid control system;

a first detector detecting when the battery voltage is out of a predetermined normal range to produce a first detector signal;

a second detector for detecting braking of a vehicle to produce a second detector signal; and

a power supply control means, responsive to said first detector signal and the absence of said second detector signal for switching the position of said switch means from said first position to said second position for disconnecting said battery from said anti-skid control system for disabling the latter, said power supply control means being further responsive to said second detector signal for disabling said switching operation in response to said first detector signal for maintaining connection between said battery and said anti-skid control system in order to enable said anti-skid control system irrespective of said first detector signal as long as said second detector signal is present, whereby battery voltages outside of said predetermined normal range which occur during braking are prevented from disconnecting said anti-skid control system from said battery, thereby maintaining said anti-skid control system operative.

2. The fail-safe system as set forth in claim 1, wherein said second detector detects a control signal produced by said anti-skid control system demanding a decrease in the fluid pressure in a hydraulic brake system.

3. The fail-safe system as set forth in claim 1, wherein said second detector comprises a brake switch closed whenever braking is being performed.

4. The fail-safe system as set forth in claim 2, wherein said anti-skid brake control system comprises a wheel speed sensor for detecting wheel speed, a control module for processing a signal from said wheel speed sensor and producing a control signal for increasing, decreasing and holding constant the fluid pressure in said hydraulic brake system so as to optimize braking characteristics, and an electromagnetic actuator associated with said hydraulic brake system for increasing, decreasing and holding constant the fluid pressure in response to said control signal.

5. The fail-safe system as set forth in claim 3, wherein said anti-skid brake control system comprises a wheel speed sensor for detecting wheel speed, a control module for processing a signal from said wheel speed sensor and producing a control signal for increasing, decreasing and holding constant the fluid pressure in said hydraulic brake system so as to optimize braking characteristics, and an electromagnetic actuator associated with a hydraulic brake system for increasing, decreasing and holding constant the fluid pressure of said hydraulic brake system in response to said control signal.

6. The fail-safe system as set forth in claim 4, wherein said electromagnetic actuator is connected to said battery via said switch means, and said switch means connects and disconnects said actuator to and from said battery.

7. The fail-safe system as set forth in claim 5, wherein said electromagnetic actuator is connected to said battery via said switch means, and said switch means connects and disconnects said actuator to and from said battery.

8. The fail-safe system as set forth in claim 6, which further comprises means responsive to switching of said switch position from said first position to said second position for producing an alarm.

9. The fail-safe system as set forth in claim 7, which further comprises means responsive to switching of said switch position from said first position to said second position for producing an alarm.

10. The fail-safe system as set forth in claim 8, which further comprises a motor control circuit for controlling operation of a fluid pump motor for reducing fluid pressure, said motor control circuit being associated with said anti-skid control system to operate said motor when said anti-skid control system is operating.

11. The fail-safe system as set forth in claim 10, wherein said motor control circuit is responsive to said second detector signal to operate said motor.

12. An anti-skid brake control system with a fail-safe system comprising:

an anti-skid controller associated with sensors for detecting a vehicular braking condition and controlling application and releasing of braking pressure for a wheel cylinder of a vehicular brake system;

a hydraulic brake circuit incorporating an anti-skid controlling actuator for controlling braking pressure in said wheel cylinder upon detection of a control signal from said anti-skid controller;

a fluid pump disposed within the braking circuit and adapted for circulating the working fluid in said wheel cylinder to an accumulator in a brake circuit for reducing braking pressure in said wheel cylinder, which fluid pump becomes active at least in the brake releasing mode operation state of said actuator;

a vehicular battery supplying electric power for said actuator and said fluid pump for operation thereof;

a switch means disposed between said battery and said actuator and operable between a conductive state for establishing electrical communication between said battery and said actuator and a non-conductive state for blocking electrical communication between the battery and said actuator in order to place said actuator in an operational state in an application mode;

a first detector monitoring voltage of said battery and producing a first signal when the battery voltage is not within a predetermined normal range;

a second detector for detecting a vehicular braking state and producing a second detector signal upon application of a vehicle brake; and

a power supply controller responsive to said first signal in the absence of said second detector signal to operate said switch means from said conductive state to said non-conductive state for disabling said anti-skid controlling actuator, and responsive to said second detector signal to maintain said switch means at said conductive state as long as said second detector signal is present, whereby said switch means is prevented from erroneously shutting off the power supply to said actuator in response to a temporary drop of the battery voltage due to actuation of said actuator and/or said fluid pump.

13. An anti-skid brake control system with a fail-safe system therefor comprising:

a hydraulic brake circuit including a fluid pressure source and a wheel cylinder for building up therein a braking pressure;

a pressure control valve means for adjusting braking pressure in said wheel cylinder, said pressure control valve means being movable between a first position to increase said braking pressure in said wheel cylinder in response to a braking operation and a second position to decrease said braking pressure in said wheel cylinder;

an actuator, associated with said pressure control valve means, for operating said pressure control valve means between said first and second positions;

a battery for supplying electric power to said anti-skid control system;

a switch means disposed between said battery and said anti-skid control system, said switch means being operative between a first normal position for connecting said battery to said anti-skid control system and a second position for disconnecting the battery from said anti-skid control system;

a first detector detecting when that battery voltage is out of a predetermined normal range to produce a first detector signal;

a second detector for detecting braking of said vehicle to produce a second detector signal; and

a power supply control means, responsive to said first detector signal for switching the position of said switch means from said first position to said second position for disconnecting said battery from said anti-skid control system for disabling the latter and for operating said actuator to operate said pressure control valve means at said first position so as to allow adjustment of braking pressure directly responsive to said braking operation, said power supply control means being further responsive to said second detector signal for disabling said switching in response to said first detector signal for maintaining connection between said battery and said anti-skid control system in order to enable said anti-skid control system irrespective of said first detector signal as long as said second detector signal is present.