JPH0179101U

JPH0179101U -

Info

Publication number: JPH0179101U
Application number: JP1987174421U
Authority: JP
Priority date: 1987-11-17
Filing date: 1987-11-17
Publication date: 1989-05-26

Description

[Brief explanation of the drawing]

第１図は本考案に係わるフエールセーフ回路の
一実施例を示す回路図、第２図はリレー等の自己
チエツク動作を説明するためのフローチヤート、
第３図は本考案の第２の実施例を示す回路図であ
る。１……信号制御部、２……電力制御部、３……
モータ、Ｆ１……ヒユーズ、Ｔ１，Ｔ２……端子
、ＲＬ１……リレー、Ｑ１〜Ｑ４，Ｑ１０〜Ｑ１
３……トランジスタ、ＩＣ１……マイクロコンピ
ユータ、ＩＣ２……ウオツチドツグタイマ、ＩＣ
３……ワンシヨツトマルチ、ＣＰ１，ＣＰ２……
コンパレータ、Ｄ１，Ｄ２……ダイオード、ＺＤ
１……ツエナーダイオード、Ｒ１〜Ｒ２１，Ｒ３
０，Ｒ３１……抵抗、Ｃ１〜Ｃ４……コンデンサ
。 FIG. 1 is a circuit diagram showing an embodiment of a fail-safe circuit according to the present invention, and FIG. 2 is a flowchart for explaining self-check operation of relays, etc.
FIG. 3 is a circuit diagram showing a second embodiment of the present invention. 1...Signal control section, 2...Power control section, 3...
Motor, F1...Fuse, T1, T2...Terminal, RL1...Relay, Q1~Q4, Q10~Q1
3...Transistor, IC1...Microcomputer, IC2...Watchdog timer, IC
3...One shot multi, CP1, CP2...
Comparator, D1, D2...diode, ZD
1... Zener diode, R1 to R21, R3
0, R31...Resistor, C1-C4...Capacitor.

Claims

[Scope of Claim for Utility Model Registration] (1) In a fail-safe circuit of a signal control unit that controls a rear wheel steering device consisting of a power relay, a motor, and a power control unit that drives the motor, a reset from a watchdog timer is provided. a microcomputer that inputs a signal and a predetermined signal, opens the relay in response to the reset signal, and opens the contacts of the relay when the predetermined signal indicates an abnormality; a first abnormality detection circuit that outputs an abnormality signal;
The microcomputer includes a second abnormality detection circuit that outputs a second abnormality signal in response to the predetermined signal, and a holding circuit that holds the output levels from the first and second abnormality detection circuits, and the microcomputer A fail-safe circuit characterized in that it performs a self-check at predetermined time intervals and opens the contacts of the relay by means of an alternative port in the event of a port failure. (2) The fail-safe circuit according to claim 1, wherein the predetermined signal is a signal indicating that the current flowing through the coil of the relay is excessive. (3) The fail-safe circuit according to claim 1, wherein the predetermined signal is a signal indicating that the current flowing through the contacts of the relay is excessive. (4) Self-check for shorted transistors, stuck relay contacts, or grounding downstream of the relay coil.
The fail-safe circuit according to claim 1, which is a utility model registration, characterized in that it checks for a short circuit in a relay coil, an open circuit in a relay coil, and a defective contact in a relay.