AIRBAG CONTROL UNIT

• US 20150001837A1
• Filed: 06/27/2014
• Published: 01/01/2015
• Est. Priority Date: 06/27/2013
• Status: Active Grant

• Current Assignee: Zodiac Cabin Controls
• Original Assignee: Zodiac Cabin Controls
• Inventors: Glck, Susanne, Hoya Arija, Sara, Rschl, Stefan, Pohl, Jonas
• Granted Patent: US 9,283,912 B2
• Time in Patent Office: Days
• US Class Current: 280/735
• CPC Class Codes: B60R 2021/01047 Architecture
• CPC Class Codes: B60R 21/01336 using filtering
• CPC Class Codes: B60R 21/01558 monitoring crash strength
• 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

Abstract

An airbag control unit including two, independent trigger control paths that operate sets of first and second switches placed in series with a power source, sets of trigger outputs, and a ground. Each trigger control path is capable of detecting a shock and determining if the shock is a crash-level shock. Each trigger control path outputs a trigger signal to a switch when a crash-level shock is detected and the trigger control path is armed. Current is only supplied to the trigger output if both trigger control paths sense a crash-level shock and are armed. Upon sensing a shock, each trigger control path can power a power hold element that provides temporary power to the trigger control paths long enough to process the shock signals and generate any necessary trigger signals.

Claims

1. An airbag control unit comprising:

at least one first switch and at least one second switch coupled in series with at least one trigger output between a power source and a ground;

a first trigger control path coupled to the power source and operable to supply a first trigger signal to the at least one first switch in response to sensing a crash-level shock, wherein the at least one first switch is operable to allow current flow therethrough in response to the first trigger signal;

a second trigger control path coupled to the power source and operable to supply a second trigger signal to the at least one second switch in response to sensing the crash-level shock, wherein the at least one second switch is operable to allow current flow therethrough in response to the second trigger signal.

2. The airbag control unit of claim 1 additionally comprising a maintenance interface operable to disable at least one of the first trigger control path and the second trigger control path, wherein the first trigger control path is unable to supply the first trigger signal when disabled and the second trigger control path is unable to supply the second trigger signal when disabled.

3. The airbag control unit of claim 1, wherein:

the first trigger control path comprises a first acceleration sensor coupled to the power source, a first filter coupled to the first acceleration sensor, and a first signal conditioner coupled to the first filter; and

the second trigger control path comprises a second acceleration sensor coupled to the power source, a second filter coupled to the second acceleration sensor, and a second signal conditioner coupled to the second filter.

4. The airbag control unit of claim 3, wherein:

the first filter is a first low-pass filter;

the second filter is a second low-pass filter;

the first signal conditioner is a first Schmitt-trigger circuit; and

the second signal conditioner is a second Schmitt-trigger circuit.

5. The airbag control unit of claim 3, wherein:

the first trigger control path further comprises a first nonvolatile memory for storing a first armed status and a first logic gate coupled to the first signal conditioner and the first nonvolatile memory, wherein the first logic gate is operable to supply the first trigger signal only in response to receiving a first conditioned signal while the first armed status is enabled; and

the second trigger control path further comprises a second nonvolatile memory for storing a second armed status and a second logic gate coupled to the second signal conditioner and the second nonvolatile memory, wherein the second logic gate is operable to supply the second trigger signal only in response to receiving a second conditioned signal while the second armed status is enabled.

6. The airbag control unit of claim 5 additionally comprising a maintenance interface coupled to the first nonvolatile memory for setting the first armed status and coupled to the second nonvolatile memory for setting the second armed status.

7. The airbag control unit of claim 1, wherein:

the at least one first switch includes four first switches;

the at least one second switch includes four second switches;

the at least one trigger output includes four trigger outputs; and

the four first switches are each coupled in series with respective ones of the four second switches and respective ones of the four trigger outputs between the power source and the ground.

8. The airbag control unit of claim 1, wherein each of the at least one first switch and the at least one second switch is a transistor switch.

9. The airbag control unit of claim 1 additionally comprising a power hold element coupled to the first trigger control path and the second trigger control path for supplying a voltage to the first trigger control path and the second trigger control path for a duration, wherein the first trigger control path and the second trigger control path are further operable to initially supply power to the power hold element in response to sensing an uncritical shock or the crash-level shock.

10. The airbag control unit of claim 9 additionally comprising:

a first brown out detector coupled to the power hold element and the first trigger path for disabling power to the first trigger path when the voltage drops below a predetermined limit; and

a second brown out detector coupled to the power hold element and the second trigger path for disabling power to the second trigger path when the voltage drops below the predetermined limit.

11. A method of triggering an airbag inflator comprising:

providing a first trigger signal in response to sensing a crash-level shock by a first trigger control path;

providing a second trigger signal in response to sensing the crash-level shock by a second trigger control path;

outputting a voltage to a trigger output in response to providing the first trigger signal and providing the second trigger signal.

12. The method of claim 11, wherein outputting the voltage further includes closing at least one first switch in response to providing the first trigger signal and closing at least one second switch in response to providing the second trigger signal.

13. The method of claim 12, wherein:

providing the first trigger signal further includes;

generating a first shock signal in response to sensing the crash-level shock by a first acceleration sensor;

filtering the first shock signal to generate a first filtered signal;

conditioning the first filtered signal to generate a first conditioned signal; and

providing the second trigger signal further includes;

generating a second shock signal in response to sensing the crash-level shock by a second acceleration sensor;

filtering the second shock signal to generate a second filtered signal;

conditioning the second filtered signal to generate a second conditioned signal.

14. The method of claim 13, wherein:

providing the first trigger signal further includes reading a first armed status from a first nonvolatile memory, and wherein providing the first trigger signal only occurs when the first armed status is enabled; and

providing the second trigger signal further includes reading a second armed status from a second nonvolatile memory, and wherein providing the second trigger signal only occurs when the second armed status is enabled.

15. The method of claim 11, further comprising:

charging a power hold element in response to sensing a sensed shock selected from the group consisting of an uncritical shock and the crash-level shock; and

supplying power to the first trigger control path and the second trigger control path from the power hold element.

16. The method of claim 15, additionally comprising ceasing to supply power to the first trigger control path and the second trigger control path in response to sensing a supply voltage of the power hold element below a predefined limit.

17. An airbag control unit comprising:

a first acceleration sensor coupled to a first filter which is coupled to a first signal conditioner;

a first AND logic gate coupled to the first signal conditioner and a first nonvolatile memory;

a second acceleration sensor coupled to a second filter which is coupled to a second signal conditioner;

a second AND logic gate coupled to the second signal conditioner and the first nonvolatile memory or a second nonvolatile memory;

a power source coupled to the first acceleration sensor, the second acceleration sensor, and at least one trigger output;

at least one first switch coupled to the first AND logic gate and the at least one trigger output; and

at least one second switch coupled to the at least one first switch, the second AND logic gate, and a ground.

18. The airbag control unit of claim 17, further comprising:

a power hold element coupled to the first acceleration sensor and the second acceleration sensor, the power hold element further coupled to a first analysis element and a second analysis element, wherein the first analysis element is selected from the group consisting of the first filter and the first signal conditioner, and wherein the second analysis element is selected from the group consisting of the second filter and the second signal conditioner.

19. The airbag control unit of claim 18, further comprising:

at least one brown out detector coupled to the power hold element, the first analysis element, and the second analysis element.

20. The airbag control unit of claim 19, further comprising a maintenance interface coupled to the first nonvolatile memory and the second nonvolatile memory, wherein the second AND logic gate is coupled to the second nonvolatile memory.