VEHICLE SAFETY SYSTEM CONTROL CIRCUIT HAVING A MALFUNCTION INDICATOR

• US 3,863,208 A
• Filed: 02/19/1974
• Issued: 01/28/1975
• Est. Priority Date: 02/14/1973
• Status: Expired due to Term

• Current Assignee: TRW Vehicle Safety Systems Incorporated (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Morton S. Balban
• Inventors: Balban, Morton S.
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US05/443,582
• Time in Patent Office: 343 Days
• Field of Search: 340/52R,52B,52D,52F,52H,53,59,60,244,248R,248A,248E 307/1R,1LS
• US Class Current: 280/735
• CPC Class Codes: B60R 21/01 Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents electrical circuits for transmission of signals between steering wheel and the vehicle itself B60R16/027; for electrically actuating belt retractor locking means B60R22/343

Abstract

A control circuit serves for controlling operation of a passive restraint safety system for protecting vehicle occupants during a collision. The circuit includes a sensing circuit portion for sensing a crash condition and a firing circuit portion for electrically actuating a safety device actuator, such as a detonator coil. Monitoring circuitry serves to continuously monitor both the sensing portion and the firing portion for circuit malfunctions and provides a warning indication to the vehicle operator in the event of a detected malfunction in either circuit portion. The monitoring circuit also monitors a crash sensor arming switch to determine whether it is closed rendering the sensor operable, and monitors the capacitor or redundant supply voltage to determine if that voltage level is proper. Other components and functions are monitored to provide a fault indication in the event of a detected malfunction.

Claims

1. A vehicle safety system control circuit comprising a crash sensor series circuit and a firing series circuit, said crash sensor series circuit including crash sensor switch means having a normal unactuated condition and an actuated condition representative of a crash condition, said firing series circuit including electrically energizable actuator means for upon energization actuating a vehicle safety device, power supply circuit means for providing operating voltage for said circuits, second switching means having a normal condition and a actuated condition for connecting said sensor series circuit and said firing series circuit together in series with said power supply circuit means so that when said sensor switch means is in its actuated condition an energizing circuit is completed through said sensor switch means and said second switch means for firing current to flow from said power supply circuit means to energize said actuator means, means for continuously effecting flow of a first test current from said power supply circuit means through said sensor series circuit while said second switch means is in its normal condition, means for continuously effecting flow of a second test current from said power supply circuit means through said firing series circuit while said second switch means is in its normal condition, and output circuit means responsive to said test currents for providing an output indication as to a circuit malfunction in either said sensor series circuit or in said firing series circuit in dependence upon the magnitudes of said test currents.

2. A vehicle safety system control circuit as set forth in claim 1 wherein said sensor switch means is actuated to its actuated condition in response to vehicle deceleration of A first predetermined magnitude and said second switching means is a deceleration responsive switch means actuated to its actuated condition in response to vehicle deceleration of a second predetermined magnitude less that that of said first predetermined magnitude so that both switching means must be actuated to their actuated conditions for completion of said energizing circuit for energizing said actuator means.

3. A vehicle safety system control circuit as set forth in claim 1 wherein said means for effecting flow of a first test current includes current limiting means connected across said sensor switching means for limiting said test current flow to a magnitude less than that required to energize said actuator means.

4. A vehicle safety system control circuit as set forth in claim 3 including a second said crash sensor switching means connected in parallel with said first crash sensor switching means with each having a said current limiting means connected thereacross to limit test current flow therethrough to a magnitude less than that required to energize said actuator means.

5. A vehicle safety system control circuit as set forth in claim 3 including normally closed position switch means connected in series with said crash sensor switch means in such a manner that current is permitted to flow through said crash sensor switch means in either its actuated condition or its normal condition only when said position switch means is in its closed condition.

6. A vehicle safety system control circuit as set forth in claim 3 including circuit means for developing a sensor circuit test voltage of a magnitude representative of the magnitude of the first test current flowing through said sensor series circuit.

7. A vehicle safety system control circuit as set forth in claim 6 wherein said output circuit means includes voltage comparing means for comparing said sensor test voltage with a reference voltage and providing a fault output indication in dependence upon said comparison.

8. A vehicle safety system control circuit as set forth in claim 7 wherein said comparing means includes means for comparing said sensor test voltage with a high level reference voltage and a low level reference voltage and providing a said fault indication signal only when said sensor circuit test voltage is not of a magnitude between said low and high reference voltages.

9. A vehicle safety system control circuit as set forth in claim 1 wherein said means for effecting said second test current includes current limiting means connecting said power supply circuit means with said firing series circuit for limiting the magnitude of the said second test current so as to be less than the magnitude required for energizing said actuator means.

10. A vehicle safety system control circuit as set forth in claim 9 wherein said output circuit means includes means for comparing a test voltage developed across said firing series circuit due to said second test current flow therethrough with a refrence voltage and providing a fault indicating output signal in dependence upon said comparison.

11. A vehicle safety system control circuit as set forth in claim 10 wherein said comparing means includes circuit means for comparing said test voltage with a high reference voltage and a low reference voltage and providing a fault indication signal whenever said test voltage is not of a magnitude between that of said high and low reference voltages.

12. A vehicle safety system control circuit as set forth in claim 1 including circuit means for developing a first voltage representative of the magnitude of said first test current and a second voltage representative of the magnitude of said second test current, and said output circuit means includes means responsive to said first and second test voltages for producing an output fault signal in the event that either of said test voltages is of a magnitude outside of a given voltage range associated with that voltage.

13. A vehicle safety system contRol circuit as set forth in claim 1 wherein said output circuit means includes fault indicator lamp means and means for energizing said fault indicator lamp means to present a visual display representative of a fault condition in said control circuit.

14. A vehicle safety system control circuit as set forth in claim 13 includes circuit means for providing a simulated fault indicating signal and circuit means responsive to said simulated signal for effecting energization of said fault indicating lamp means.

15. A vehicle safety system control circuit as set forth in claim 1 including fault time recorder indicating means for providing an indication representative of the time duration of a said output circuit malfunction.

16. A vehicle safety system control circuit as set forth in claim 1 wherein said output circuit means includes lamp means, logic circuit means for energizing said lamp means in response to a malfunction signal, and circuit means for applying a said malfunction signal to said logic circuit means so long as either said first or said second test current is of a magnitude outside of prescribed limits therefore.

17. A vehicle safety system control circuit as set forth in claim 16 including circuit means for monitoring said capacitor or redundant power supply circuit means for applying a said malfunction signal to said logic circuit means so long as said capacitor or redundant supply voltage is of magnitude less than a predetermined magnitude.

18. A vehicle safety system control circuit as set forth in claim 16 including position switch means having a normally closed condition and connected in series with said sensor switch means to complete a circuit for current flow through said sensor switch means, and circuit means for applying a said malfunction signal to said logic circuit means so long as said position switch means is in an open condition.

19. A vehicle safety system control circuit as set forth in claim 16 including pressure indicating switch means having a normally closed condition and an open condition representative of low fluid pressure in a fluid reservoir for inflating a safety confinement in response to actuation of said electrically actuatable means, and circuit means for applying a said malfunction signal to said logic circuit means so long as said pressure indicating switch means is in its open condition.

20. A monitoring circuit for a system including an electro-explosive device to be actuated by a predetermined minimum current upon the occurrence of a predetermined circumstance, means for sensing the occurrence of the predetermined circumstance, and means providing the minimum current in response thereto, said circuit comprising:

a. means providing a first test current through said sensing means, said first test current being less than said minimum current;

b. means providing a second test current through said electro-explosive device, said second test current being less than said minimum current; and

c. output circuit means responsive to said first and second test currents for providing an indication of a fault in either said sensing means or said electro-explosive device.

21. The circuit as set forth in claim 20 including circuit means for developing first and second test voltages representative of said first and second test currents, and wherein said output circuit means includes means for comparing said first and second test voltages with a reference voltage and providing a fault indication responsive to said comparison.

22. The circuit as set forth in claim 21 wherein said voltage comparing means includes means for comparing said first and second test voltages with a high level reference voltage and with a low level reference voltage and providing a fault indication only when one of said test voltages is either higher than said high level reference voltage or lower than said low level reference voltage.

23. The circuit as set forth in claim 20 wherein said output circuit means includes:

a. inDicator means to provide a visual representation of a fault condition in said system; and

b. circuit means for providing a fault indication signal and energizing said indicator means in response thereto.

24. The circuit as set forth in claim 20 including fault time indicating means for providing an indication representative of the time duration of a fault indication.

25. A control circuit for a system including an electro-explosive device to be actuated by a predetermined minimum current upon the occurrence of a predetermined circumstance and means for sensing the occurrence of the predetermined circumstance, said circuit comprising:

a. switch means adapted to be operably connected to the sensing means and having a normal unactuated condition and an actuated condition representative of the occurrence of the circumstance;

b. electrically energizable means for actuating the electro-explosive device in response to said minimum current;

c. said switch means and said actuating means being operably connected electrically in series and adapted to be connected to a source of power;

d. means providing a first test current through said switch means, said first test current being less than said minimum current;

e. means providing a second test current through said actuating means, said second test current being less than said minimum current; and

f. output circuit means responsive to said first and second test currents for providing an indication of a fault in either of said switch means or said actuating means.

26. The circuit as set forth in claim 25 wherein said means providing a first test current includes current limiting means connected across said switch means for limiting said first test current to less than said minimum current.

27. The circuit as set forth in claim 25 wherein said means providing a second test current includes current limiting means connected across said actuating means for limiting said second test current to less than said minimum current.

28. The circuit as set forth in claim 25 including a redundant power supply circuit means capable of being connected electrically in series with said switch means and said actuating means to supply power thereto if a discontinuity occurs in the series electrical connection between said power source, said switch means and said actuating means.

29. The circuit as set forth in claim 28 wherein said redundant power supply circuit means comprises a capacitor, and including means for monitoring said capacitor to provide a fault indication if the voltage stored by said capacitor is less than a predetermined minimum.

30. A control circuit for a system including an electro-explosive device to be actuated by a predetermined minimum current upon the occurrence of a predetermined circumstance and means for sensing the occurrence of the predetermined circumstance, said circuit comprising:

a. sensor circuit means adapted to be operably connected to the sensing means and including sensor switch means having a normal unactuated condition and an actuated condition representative of the occurrence of the circumstance;

b. firing circuit means including electrically energizable actuator means for actuating the electro-explosive device in response to said minimum current;

c. said sensor circuit means and said firing circuit means being operably connected electrically in series and adapted to be connected to a source of power;

d. means providing a first test current through said sensor circuit means, said first test current being less than said minimum current;

e. means providing a second test current through said firing circuit means, said second test current being less than said minimum current; and

f. output circuit means responsive to said test currents for providing an indication of a fault in said sensor circuit means or said firing circuit means.

31. The circuit as set forth in claim 30 wherein said means providing a first test current includEs current limiting means connected across said sensor switch means for limiting said first test current to less than said minimum current.

32. The circuit as set forth in claim 30 including normally closed position switch means connected in series with said sensor switch means to permit current to flow through said sensor switch means in both its actuated condition and its normal condition only when said position switch means is in its closed condition.

33. The circuit as set forth in claim 30 including circuit means for developing a sensor circuit test voltage representative of said first test current, and wherein said output circuit means includes means for comparing said sensor circuit test voltage with a reference voltage and providing a fault indication responsive to said comparison.

34. The circuit as set forth in claim 33 wherein said voltage comparing means includes means for comparing said sensor circuit test voltage with a high level reference voltage and with a low level reference voltage and providing an indication of a fault only when said sensor circuit test voltage is either higher than said high level reference voltage or lower than said low level reference voltage.

35. The circuit as set forth in claim 30 wherein said means providing a second test current includes current limiting means adapted to be operably connected between the power source and said firing circuit means for limiting said second test current to less than said minimum current.

36. The circuit as set forth in claim 35 including circuit means for developing a firing circuit test voltage representative of said second test current, and wherein said output circuit means includes means for comparing said firing circuit test voltage with a reference voltage and providing a fault indication responsive to said comparison.

37. The circuit as set forth in claim 36 wherein said voltage comparing means includes means for comparing said firing circuit test voltage with a high level reference voltage and with a low level reference voltage and providing a fault indication only when said firing circuit test voltage is either higher than said high level reference voltage or lower than said low level reference voltage.

38. The circuit as set forth in claim 30 wherein said output circuit means includes:

a. fault indicator lamp means to provide a visual representation of a fault condition in said control circuit;

b. means for energizing said fault indicator lamp means;

c. circuit means for providing a simulated fault indicating signal; and

d. circuit means responsive to said simulated fault indicating signal for effecting energization of said fault indicator lamp means.

39. The circuit as set forth in claim 30 including fault time recorder indicating means for providing an indication representative of the time duration of a fault indication.

40. The circuit as set forth in claim 30 including a redundant power supply circuit means capable of being connected electrically in series with said sensor circuit means and said firing circuit means to supply power thereto if a discontinuity occurs in the series electrical connection between said power source, said firing circuit means and said sensor circuit means.

41. The circuit as set forth in claim 40 wherein said redundant power supply circuit means comprises a capacitor, and including means for monitoring said capacitor to provide a fault indication if the voltage stored by said capacitor is less than a predetermined minimum.

42. A control circuit for a vehicle occupant restraint system including a crash sensor and an electro-explosive device to be actuated by a predetermined minimum current upon the occurrence of a crash condition, to cause the inflation of an inflatable confinement, said circuit comprising:

a. crash sensor circuit means adapted to be operably connected to the crash sensor and including sensor switch means having a normal unactuated condition and an actuated condition representative of a cRash condition;

b. firing circuit means including electrically energizable actuator means for actuating the electro-explosive device in response to said minimum current;

c. said crash sensor circuit means and said firing circuit means being operably connected electrically in series and adapted to be connected to a source of power;

d. means providing a first test current through said crash sensor circuit means, said first test current being less than said minimum current;

e. means providing a second test current through said firing circuit means, said second test current being less than said minimum current; and

f. output circuit means responsive to said test currents for providing an indication of a fault in either of said crash sensor circuit means or said firing circuit means.

43. The control circuit of claim 42 including:

a. pressure indicating switch means having a normally closed condition and an open condition representative of a low fluid pressure in a fluid reservoir adapted to inflate the inflatable confinement; and

b. circuit means for providing a fault indication when said pressure indicating switch means is in said open condition.