FAULT DETECTOR FOR MOTOR VEHICLE SAFETY DEVICE

• US 3,849,759 A
• Filed: 02/15/1973
• Issued: 11/19/1974
• Est. Priority Date: 02/19/1972
• Status: Expired due to Term

• Current Assignee: Akio Hosaka, Kiyoshi Wazawa, Kosaku Baba
• Original Assignee: Akio Hosaka, Kiyoshi Wazawa, Kosaku Baba
• Inventors: Hosaka, Akio, Baba, Kosaku, Wazawa, Kiyoshi
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US05/332,762
• Time in Patent Office: 642 Days
• Field of Search: 340/52R,52B,52D,52F,52H,53,59,60,244R,248R,248E,250 307/1R,1LS
• US Class Current: 340/438
• CPC Class Codes: B60K 28/14 responsive to accident or emergency, e.g. deceleration, tilt of vehicle
• CPC Class Codes: B60R 21/0176 for firing circuits using only mechanical switches as collision detecting means, in series with pyrotechnic fuses
• CPC Class Codes: G07C 3/005 during manufacturing process
• CPC Class Codes: G07C 5/0825 using optical means

Abstract

A fault detector for detecting a fault or failure in an actuator of a safety device for a motor vehicle which comprises a fault recording or storing means having an electric fuse and an alarm with a pilot lamp. The fault detector may detect a faulty condition of the actuator even though the actuator could be accidentally temporarily recovered from the faulty condition for some cause or another. This is accomplished by continuing the alarm operation of the alarm in such a manner that, when the electric fuse is burnt out or melted in the event of the fault, the alarm is energized and the pilot lamp is lighted so as to start the alarm operation that stops only when the burnt out fuse is replaced. The fault detector may record or store the faulty condition of the actuator by means of the melted fuse and detect malfunction of the pilot lamp of the alarm.

Claims

1. A fault detector for an actuator of a safety device for a motor vehicle having an electrical DC power supply, which comprises:

a logic circuit comprising a plurality of comparators responsive to internal signals in an electrical circuit of a safety device actuator, an inverter receptive of a logic output signal of one of said comparators, and a first NAND gate receptiVe of logical output signals of said inverter and the remaining ones of said comparators to develop a logic circuit output signal;

a fault memory means for developing a continuous output signal in response to a logic circuit output signal representative of a fault in the safety device actuator; and

an alarm actuated in response to said output signal from said memory means.

2. A fault detector as claimed in claim 1, further comprising an additional logic circuit for detecting a source voltage of an auxiliary power source of said power supply, said additional logic circuit developing a logic output signal indicative of an auxiliary power source fault, and means applying said additional logic circuit output signal to said alarm.

3. A fault detector as claimed in claim 2, in which said additional logic circuit comprises a comparator.

4. A fault detector as claimed in claim 1, in which said fault memory means comprises a first transistor, a first resistor connected between the base of said first transistor and the output of said first NAND gate, means connecting the emitter of said first transistor to one terminal of said power supply, a memory element, means connecting the collector of said first transistor in series with said memory element to another terminal of said power supply, and a second resistor connected between said emitter and said collector.

5. A fault detector as claimed in claim 4, in which said memory element is an electrical fuse.

6. A fault detector as claimed in claim 2, in which said alarm comprises a second transistor, a third resistor connected between the base of said second transistor and a junction of said memory device and said second resistor, means connecting the emitter of said second transistor to one terminal of said power supply, an indicator, and means connecting the collector of said second transistor in series with said indicator to another terminal of said power supply.

7. A fault detector as claimed in claim 6, in which said indicator is a lamp.

8. A fault detector as claimed in claim 6, in which said alarm further comprises a second NAND gate having two inputs, means applying to one of said inputs an output of said additional logic circuit, and means applying to the other input an output of said memory means, and means connecting an output of said second NAND gate in series with said second resistor to said base of said second transistor.