Impact sensor for vehicle safety restraint system

• US 5,430,334 A
• Filed: 09/24/1992
• Issued: 07/04/1995
• Est. Priority Date: 11/19/1990
• Status: Expired due to Fees

• Current Assignee: Jack B. Meister
• Original Assignee: Echlin, Inc.
• Inventors: Meister, Jack B.
• Primary Examiner(s): Gaffin, Jeffrey A.
• Assistant Examiner(s): GANJIAN, PETER
• Application Number:
  US07/950,315
• Time in Patent Office: 1,013 Days
• Field of Search: 307/10.1, 307/121, 200/61.45 R, 200/61.45 M, 200/61.52, 200/61.53, 73/517 R, 73/518, 73/519, 73/520, 280/735, 340/438, 180/282
• US Class Current: 307/10.1
• CPC Class Codes: B60R 21/0132 responsive to vehicle motion parameters , e.g. to vehicle longitudinal or transversal deceleration or speed value
• CPC Class Codes: G01P 15/093 by photoelectric pick-up
• CPC Class Codes: G01P 15/105 by magnetically sensitive devices
• CPC Class Codes: G01P 15/11 by inductive pick-up
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: H01H 35/14 Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch wherein the liquid constitutes a contact of the switch H01H29/002
• CPC Class Codes: H01H 35/147 the switch being of the reed switch type

Abstract

A vehicle restraint system that includes an impact sensor coupled by fiber optics to an igniter for inflating an air bag. The impact sensor includes a permanent magnet disposed within a cavity and biased by magnetic force toward one end of the cavity, motion of the magnet in the cavity being sensed by a weigand wire or Hall sensor for igniting the air bag. Facility is disposed externally of the cavity for selectively adjusting the bias of the sensor and/or moving the magnet into proximity with the Hall effect or weigand wire sensor to test operative condition of the sensor.

Claims

1. A vehicle restraint system that comprises:

restraint means for positioning in a vehicle to restrain motion of an occupant upon operation of said restraint means,

an impact sensor including means for sensing vehicle impact to provide an impact signal, said impact sensor including means of non-magnetic construction having an internal cavity, a permanent magnet movably mounted within said cavity, means for resiliently urging said magnet to a first position within said cavity, and a Hall sensor positioned adjacent to said cavity for sensing motion of said magnet against force of said urging means to generate said impact signal as an electrical signal having a magnitude that varies as a continuous monotonic analog function of position of said magnet within said cavity,

means responsive to said impact signal for operation said restraint means, including means for analyzing rate of change of said analog electrical signal and operating said restraint means when said rate of change indicates a vehicle impact condition, and

means for selectively adjusting sensitivity of said impact sensor by adjustably varying force urging said magnet to said first position, said selectively adjusting means comprising an electromagnet positioned axially externally adjacent to said cavity and means for selectively varying force of attraction/repulsion of said electromagnet on said magnet.

2. The system set forth in claim 1 further comprising means coupled to said electromagnet for selectively testing operative condition of said impact sensor by magnetically urging said magnet into proximity with said magnetic sensing means.

3. The system set forth in claim 2 further comprising means for disabling operation of said means for operating said restraint means during testing of said impact sensor.

4. The system set forth in claim 3 wherein said sensor includes means for supplying said impact signal as an electrical signal, and wherein said system further includes a light emitter at said sensor responsive to said electrical signal to provide a light signal, a light sensor at said signal-responsive means for reconverting said light signal into an electrical signal, and a fiber optic connecting said light emitter to said light sensor.

5. The system set forth in claim 4 wherein said impact sensor further includes means enclosing said impact sensor and said light emitter in a housing, said light emitter including means projecting from said housing for coupling to said fiber optic.

6. The system set forth in claim 1 further comprising means operatively coupled to said electromagnet for selectively testing operative condition of said impact sensor by urging said magnet into proximity with said magnetic sensing means.

7. An acceleration sensor that comprises:

a body of non-magnetic construction have an internal cavity,

a first permanent magnet mounted within said cavity for movement therewithin between at least first and second positions spaced from each other longitudinally of said cavity,

means for resiliently urging said magnet to said first position within said cavity,

bistable magnetic flux-generating means carried by said body externally of said cavity, said flux generating means having first and second stable states of magnetic flux generated by said flux-generating means, and being responsive to proximity of a magnetic field of one polarity for switching from said first state to said second state, and to proximity of a magnetic field of polarity opposite to said one polarity for switching from said second state back to said first state, and

means positioned adjacent to said flux-generating means, and responsive to switching of said magnetic flux-generating means from said first state to said second state as a result of motion of said magnet from said first position to said second position to generate a sensor output signal,

said magnet, said cavity and said signal-generating means being constructed and arranged such that motion of said magnet from said first position to said second position switches said flux-generating means from said first state to said second state to generate said signal, and to motion of the same said magnet from said second position back to said first position under force of said resiliently urging means to switch said flux-generating means from said second state back to said first state.

8. The sensor set forth in claim 7 wherein said bistable magnetic flux-generating means comprises a length of weigand wire carried by said body on an axis parallel to said cavity.

9. The sensor set forth in claim 8 wherein said signal-generating means comprises an electrical coil positioned adjacent to said weigand wire.

10. The sensor set forth in claim 9 wherein said coil encircles said weigand wire.

12. The sensor set forth in claim 7 wherein said magnet-urging means comprises a second permanent magnet mounted within said cavity at a position opposed to said first position said first magnet, said first and second magnet having opposed like magnetic poles such that said first magnet is urged to said first position by magnetic repulsion from said second magnet.

13. The sensor set forth in claim 12 wherein said magnet-urging means further comprises magnetically permeable means positioned externally of said cavity adjacent to said first position.

14. The sensor set forth in claim 7 wherein said magnet is polarized lengthwise of said cavity, said flux-generating means being disposed externally of said cavity between said first and second positions of said magnet such that motion of said magnet from said first position to said second position and from said second position to said first position subjects said flux-generating means to varying magnetic fields of opposite polarity.

15. A vehicle restraint system that comprises:

restraint means for positioning in a vehicle to restrain motion of an occupant upon operation of said restraint means,

an impact sensor including means for sensing vehicle impact to provide an impact signal, said impact sensor including means of non-magnetic construction having an internal cavity, a permanent magnet movably mounted within said cavity, means for resiliently urging said magnet to a first position within said cavity, and a Hall sensor positioned adjacent to said cavity for sensing motion of said magnet against force of said urging means to generate said impact signal as an electrical signal having a magnitude that varies as a continuous monotonic analog function of position of said magnet within said cavity,

means responsive to said impact signal for operating said restraint means, including means for analyzing rate of change of said analog electrical signal and operating said restraint means when said rate of change indicates a vehicle impact condition, and

means operatively coupled to said magnet for selectively testing operative condition of said impact sensor by urging said magnet into proximity with said magnetic sensing means so as to generate said electrical analog signal independent of a vehicle impact condition.

16. The system set forth in claim 15 wherein said condition-testing means comprises an electromagnet disposed axially externally adjacent to said cavity.

17. The system set forth in claim 15 further comprising means coupled to said electromagnet for selectively adjusting sensitivity of said impact sensor by adjustably varying force of attraction/repulsion of said electromagnet urging said magnet to said first position.

18. The system set forth in claim 15 wherein said condition-testing means comprises an electromagnetic actuator disposed externally of said cavity and operatively coupled to said magnet.

19. A vehicle restraint system that comprises:

an impact sensor including means for sensing vehicle impact to provide an impact signal,

restraint means for positioning in a vehicle to restrain motion of an occupant upon operation of said restraint means,

means responsive to said impact signal for operating said restraint means,

fiber optic means interconnecting said sensor and said signal-responsive means for supplying said impact signal to said signal-responsive means,

said impact sensor including means of non-magnetic construction having an internal cavity, a permanent magnet movably mounted within said cavity, means for resiliently urging said magnet to a first position within said cavity, and magnetic sensing means positioned adjacent to said cavity for sensing motion of said magnet against force of said urging means to generate said impact signal as an electrical signal,

said magnetic sensing means comprising a Hall sensor for providing said electrical signal having a magnitude that varies as a continuous monotonic analog function of position of said magnet within said cavity, said means responsive to said impact signal including means for analyzing rate of change of said analog signal and operating said restraint means when said rate of change indicates a vehicle impact condition,

said fiber optic means including a light emitter at said sensor responsive to said electrical signal to provide a light signal, a light sensor at said signal-responsive means for reconverting said light signal into an electrical signal, and a fiber optic connecting said light emitter to said light sensor, and

means for selectively adjusting sensitivity of said impact sensor by adjustably varying force urging said magnet to said first position, said selectively adjusting means comprising an electromagnet positioned axially externally adjacent to said cavity and means for selectively varying force of attraction/repulsion of said electromagnet on said magnet.

20. The system set forth in claim 19 further comprising means coupled to said electromagnet for selectively testing operative condition of said impact sensor by magnetically urging said magnet into proximity with said magnetic sensing means.

21. The system set forth in claim 20 further comprising means for disabling operation of said means for operating said restraint means during testing of said impact sensor.

22. A vehicle restrain system that comprises:

an impact sensor including means for sensing vehicle impact to provide an impact signal,

restrain means for positioning in a vehicle to restrain motion of an occupant upon operation of said restraint means,

means responsive to said impact signal for operating said restraint means,

fiber optic means interconnecting said sensor and said signal-responsive means for supplying said impact signal to said signal-responsive means,

said impact sensor including means of non-magnetic construction having an internal cavity, a permanent magnet movably mounted within said cavity, means for resiliently urging said magnet to a first position within said cavity, and magnetic sensing means positioned adjacent to said cavity for sensing motion of said magnet against force of said urging means to generate said impact signal as an electrical signal,

said magnetic sensing means comprising a Hall sensor for providing said electrical signal having a magnitude that varies as a continuous monotonic analog function of position of said magnet within said cavity, said means responsive to said impact signal including means for analyzing rate of change of said analog signal and operating said restraint means when said rate of change indicates a vehicle impact condition,

said fiber optic means including a light emitter at said sensor responsive to said electrical signal to provide a light signal, a light sensor at said signal-responsive means for reconverting said light signal into an electrical signal, and a fiber optic connecting said light emitter to said light sensor, and

means operatively coupled to said magnet for selectively testing operative condition of said impact sensor by urging said magnet into proximity with said magnetic sensing means.

11. The sensor set forth in claim 22 wherein said magnet-urging means comprises magnetically permeable means positioned externally of said cavity adjacent to said first position, such that acceleration force on said magnet must overcome force of attraction between said magnet and said magnetically permeable means to move said magnet to said second position.

23. The system set forth in claim 22 wherein said condition-testing means comprises an electromagnet disposed axially externally adjacent to said cavity.

24. The system set forth in claim 22 wherein said condition-testing means comprises an electromagnetic actuator disposed externally of said cavity and operatively coupled to said magnet.