Circuit arrangement for triggering a safety system

• US 4,933,570 A
• Filed: 01/22/1988
• Issued: 06/12/1990
• Est. Priority Date: 02/24/1987
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Matschi, Helmut, Swart, Marten
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): IP, SHIK LUEN PAUL
• Application Number:
  US07/147,337
• Time in Patent Office: 872 Days
• Field of Search: 307/9, 307/10 R, 307/105 B, 180/268, 180/270, 180/271, 180/272, 180/273, 180/282, 180/283, 180/287, 180/274, 280/734, 280/735, 280/736, 340/429, 340/436, 340/457.1
• US Class Current: 307/10.1
• CPC Class Codes: B60R 21/017 including arrangements for providing electric power to safety arrangements or their actuating means, e.g. to pyrotechnic fuses or electro-mechanic valves
• CPC Class Codes: B60R 21/0173 Diagnostic or recording means therefor

Abstract

A circuit arrangement for triggering a safety system. A circuit arrangement serves the purpose of triggering a motor vehicle air bag system and contains an energy source, at least one release switch and at least two series branches connected in parallel and each branch has a tripping device for an air bag. A series capacitor is provided in every series branch, this capacitor limiting the current quantity in the tripped case in order to guarantee a reliable tripping of the further tripping device which acts with a time delay.

Claims

1. A circuit arrangement for triggering a safety system, particularly an air bag system, having an energy source connected in series with at least one release switch also in series with at least two series branches connected in parallel, each of which contains a tripping device for the safety system, comprising a capacitor in each of said branches, said capacitor limiting the charge amount flowing through the respective series branch.

7. The circuit arrangement according to claim 1, wherein a resistor is connected in parallel to each of said capacitors, respectively.

2. A circuit arrangement for triggering a safety system, particularly an air bag system, having an energy source connected in series with at least one release switch also in series with at least two series branches connected in parallel, each of which contains a tripping device for the safety system, comprising a capacitor in each of said series branches, said capacitor limiting the charge amount flowing through the respective series branch, and an evaluator receiving a voltage at each of said capacitors, the evaluator acquiring this voltage at the end of a measuring interval which begins with the point in time of tripping and storing the voltage value thereof in a memory.

3. The circuit arrangement according to claim 2, wherein the evaluator receives a voltage at every tripping device and identifies the point in time of tripping from a voltage discontinuity.

4. The circuit arrangement according to claim 3, wherein the evaluator derives another value from the voltage and stores said another value in the memory.

5. The circuit arrangement according to claim 2, wherein the content of the memory can only be erased by mechanical destruction.

6. The circuit arrangement according to claim 2, wherein the evaluator contains an integrated circuit connected to a microprocessor which is connected to said memory.

8. A circuit arrangement for triggering a safety system, comprising:

an energy source;

at least two series circuit branches connected in parallel, each of said circuit branches connected between said energy source and ground, and having at least a capacitor for limiting the current flowing through the circuit branch in series with a tripping device for activating the safety system.

9. The circuit arrangement according to claim 8, wherein said circuit arrangement further comprises a release switch mechanism having at least two mechanically coupled release switches connected between said energy source and said two circuit branches, one release switch associated with one circuit branch and the other release switch associated with the other circuit branch.

10. The circuit arrangement according to claim 8, wherein said circuit arrangement further comprises a resistor connector in parallel to said capacitor for each of said circuit branches.

11. The circuit arrangement according to claim 8, wherein said circuit arrangement further comprises at least one release switch in series with said energy source and said circuit branches.

12. A circuit arrangement for triggering a safety system, comprising:

an energy source;

at least two series circuit branches connected in parallel, each of said circuit branches connected between said energy source and ground;

each of said circuit branches having at least a capacitor for limiting the current flowing through the circuit branch in series with a tripping device for activating the safety system; and

an evaluator which receives a voltage at each of said capacitors, the evaluator acquiring this voltage at the end of a measuring interval which begins with the point in time of tripping and stores the voltage value thereof in a memory.

13. The circuit arrangement according to claim 12, wherein said evaluator receives a voltage at every tripping device and identifies the point in time of tripping from a voltage discontinuity.

14. The circuit arrangement according to claim 13, wherein said evaluator has an integrated circuit for interfacing with said circuit branches, a programmable read only memory, and a microprocessor connected to said integrated circuit and said programmable read only memory.