Shock sensor

• US 5,506,568 A
• Filed: 05/30/1995
• Issued: 04/09/1996
• Est. Priority Date: 05/30/1995
• Status: Expired due to Term

• Current Assignee: Nutek Corp.
• Original Assignee: Nutek Corp.
• Inventors: Chen, Chau-Ho
• Primary Examiner(s): SWANN III, GLEN R
• Application Number:
  US08/449,481
• Time in Patent Office: 315 Days
• Field of Search: 340/566, 340/429, 307/117
• US Class Current: 340/566
• CPC Class Codes: G08B 13/1681 using infrasonic detecting means, e.g. a microphone operating below the audible frequency range

Abstract

A shock sensor includes a mass suspended in a flexible support arranged to resonate when subjected to a mechanical shock, a microphone spaced closely to the mass, the mass and microphone forming a first air pressure chamber with the flexible support for transmittal therethrough of air pressure waves from the resonating mass to the microphone, the microphone arranged to produce an electronic signal when it detects changes in air pressure from the pressure waves traveling through the chamber.

Claims

1. A shock sensor comprising:

a) a mass suspended in a flexible support arranged to resonate when subjected to a mechanical shock; and

b) a microphone spaced closely to said mass,

said mass and said microphone forming a first air pressure chamber with said flexible support for transmittal therethrough of air pressure waves from said resonating mass to said microphones,

said microphone being arranged to produce an electronic signal when it detects changes in air pressure from the pressure waves traveling through said chamber.

2. The shock sensor of claim 1 further including an electronic circuit connected to said microphone for processing said signal to produce an alarm.

3. The shock sensor of claim 1 wherein said mass is asymmetrical to resonate upon receipt of a shock from any direction.

4. The shock sensor of claim 1 wherein said mass is suspended at a point spaced apart from its center of gravity.

5. The shock sensor of claim 1 wherein said mass comprises:

a) a large mass portion;

b) a smaller mass portion spaced apart from said large mass portion; and

,

c) a narrow, elongated, portion interconnecting said large mass portion and said smaller mass portion.

6. The shock sensor of claim 5 wherein said large mass portion is shaped as a round.

7. The shock sensor of claim 5 wherein said smaller mass portion is shaped as a round.

8. The shock sensor of claim 1 wherein said mass is centrally suspended over said microphone for transmission of maximum vibrations thereto.

9. The shock sensor of claim 1 wherein said mass and said microphone are arranged in spaced-apart, facing relationship.

10. The shock sensor of claim 1 wherein said mass forms the upper part of said first air chamber.

11. The shock sensor of claim 1 wherein said microphone is of the electret type.

12. The shock sensor of claim 1 wherein said microphone includes a variable capacitor mounted for receipt of air pressure waves emanating from said mass.

13. The shock sensor of claim 1 wherein said microphone closes off said air chamber to make it sealed from the outside.

14. The shock sensor of claim 1 wherein said microphone includes a hard, outer jacket and an aperture for receiving therethrough the pressure waves generated by said resonating mass.

15. The shock sensor of claim 1 wherein said microphone includes a pair of pins extending therefrom for carrying the signal produced upon receipt of the pressure waves from said resonating mass.

16. The shock sensor of claim 1 wherein said microphone forms the lower part of said first air chamber.

17. The shock sensor of claim 1 further including a protective case surrounding said sensor.

18. The shock sensor of claim 1 further including a second air chamber surrounding said first air chamber for insulating said mass from impact of shocks and sounds from non-intrusive events.

19. The shock sensor of claim 18 wherein said second air chamber is cylindrical in shape.

20. The shock sensor of claim 1 wherein said first air chamber is cylindrical in shape.

21. The shock sensor of claim 1 further including mounting hardware for mounting said sensor in the passenger compartment of said vehicle.

22. A method of indicating receipt of a shock from an intrusion into a protected area comprising the steps of:

a) suspending a mass in a flexible support in said area, so that it may mechanically resonate upon receipt of the shock thereto;

b) arranging said resonance to produce a series of air pressure waves; and

,

c) directing said air pressure waves to a microphone for generating an electrical signal in response thereto.

23. The method of claim 22 wherein said step of suspending a mass in a flexible support includes the step of arranging said mass in said flexible support to be supported at a point spaced apart from its center of gravity.

24. The method of claim 22 wherein said step of arranging said resonance to produce a series of air pressure waves includes the step of housing said mass in a first air chamber in close proximity to said microphone set in facing relationship thereto.

25. The method of claim 22 including the additional step of processing the electric signal produced by said microphone to a signal that indicates an intrusive event.

26. The method of claim 22 including the additional step of housing said first air chamber in a second air chamber, surrounding said first air chamber, to attenuate shocks from non-intrusive events from impacting said mass.