Fail-safe system in a power regulation circuit for an automotive electronic circuit

• US 4,707,758 A
• Filed: 09/24/1982
• Issued: 11/17/1987
• Est. Priority Date: 09/29/1981
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Matsuda, Toshiro
• Primary Examiner(s): SALATA, ANTHONY J
• Assistant Examiner(s): Wysocki, A. Jonathan
• Application Number:
  US06/423,186
• Time in Patent Office: 1,880 Days
• Field of Search: 303/92, 361/18, 361/90, 361/87, 307/355, 307/269, 307/356, 307/297, 340/636, 340/663, 323/267, 323/280, 323/281
• US Class Current: 361/18
• CPC Class Codes: B60T 2270/414 Power supply failure
• CPC Class Codes: B60T 8/885 using electrical circuitry

Abstract

A fail-safe system in a power regulation circuit for an automotive electronic circuit such as electronic anti-skid brake control system, which fail-safe system can perform fail-safe operation even when the power regulation circuit is damaged and thereby the supply voltage from the power regulation circuit varies significantly. The fail-safe system in a power regulation circuit includes a monitor power supply circuit independently of the power regulation circuit. The monitor power supply circuit is adapted to produce a reference signal to be compared with the output of the power regulation circuit in a fail-safe circuit. The fail-safe circuit produces an error signal when the output signal value drops below a given threshold defined by the reference signal value to activate an alarm signal generator and disconnect an actuator controlled by the control system in order to prevent the actuator from malfunctioning due to errors in the control system.

Claims

1. A fail-safe system in a power regulation circuit of an automotive electronic circuit, comprising:

a power source producing unregulated output power;

the power regulation circuit connected to said power source and adapted to regulate said unregulated output power to produce regulated system power having a substantially constant output voltage, and to supply said regulated system power to said automotive electronic circuit;

a monitor power supply circuit connected to said power source independently of said power regulation circuit and adapted to produce a reference voltage to be compared with said output voltage of said power regulation circuit, said reference voltage representative of an allowable range of variation of said output voltage of said power regulation circuit; and

means for comparing said output voltage of said power regulation circuit with said reference voltage and for disabling said automotive electric circuit when said output voltage is out of said allowable range, and also for monitoring said reference voltage utilizing said output voltage of said power regulation circuit for detecting malfunction of said monitor power supply circuit to disable said automative electric circuit when malfunction of said monitor power supply circuit is detected.

4. The system as set forth in claim 1, 2 or 3, which further comprises an indicator lamp responsive to said means for indicating malfunction of said power regulation circuit when the output voltage is out of said allowable variation range.

2. A fail-safe system in a power regulation circuit of an automotive electronic circuit, comprising:

a power source producing unregulated output power;

the power regulation circuit connected to said power source and adapted to regulate said unregulated output power to produce regulated system power having a substantially constant output voltage, and to supply said regulated system power to said automotive electronic circuit;

a monitor power supply circuit connected to said power source independently of said power regulation circuit and adapted to produce a reference signal; and

means for produce first and second reference voltages to define an allowable range of variation of the output voltage of said power regulation circuit on the basis of said reference signal, for detecting when said output voltage of said power regulation circuit is out of said allowable range for disabling said automotive electronic circuit in response thereto, and for monitoring said reference signal for detecting failure of operation of said monitor power supply circuit based on variation of said reference signal value and disabling said electronic circuit when failure of operation of said monitor power supply circuit is detected.

3. A fail-safe system in a power regulation circuit of an electronic anti-skid brake control system, comprising:

a power source;

a power regulation circuit connected to said power source for outputting electrical power having a substantially constant voltage and said anti-skid brake control system;

a monitor power supply circuit connected to said power source independently of said power regulation circuit and adapted to produce a constant voltage reference signal; and

means for producing first and second reference voltages from said constant voltage reference signal to define an allowable range of variation of said output voltage of said power regulation circuit, for detecting when the output voltage is out of said allowable variation range to disable said anti-skid brake control system, for monitoring said constant voltage reference signal to detect fluctuation of said reference signal voltage, and for disabling said anti-skid brake control system if said fluctuations are detected.

5. A fail-safe system in a power regulation circuit of an automotive electronic circuit comprising:

a power source producing unregulated output power, said power source supplying unregulated output power;

the power regulation circuit connected to said power source and regulating said unregulated output power to produce regulated system power having a substantially constant output voltage, and supplying said regulated system power to said automotive electronic circuit;

a monitor power supply circuit connected to said power source to receive said unregulated output power independently of said power regulation circuit and producing a reference voltage to be compared with said output voltage of said power regulation circuit, said reference voltage representative of an allowable range of variation of said output voltage of said power regulation circuit; and

means for comparing said output voltage of said power regulation circuit with said reference voltage and for disabling said automotive electric circuit when said output voltage is out of said allowable variation range,

whereby the regulated system power from said power regulation circuit which is outside of said allowable range can be detected even when said power source for said power regulation circuit fluctuates.