Inertia and inductance switches

• US 5,334,963 A
• Filed: 10/22/1992
• Issued: 08/02/1994
• Est. Priority Date: 10/22/1992
• Status: Expired due to Fees

• Current Assignee: University of Alabama in Huntsville (University of Alabama System)
• Original Assignee: University of Alabama in Huntsville (University of Alabama System)
• Inventors: Wessling, Francis C.
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US07/964,932
• Time in Patent Office: 649 Days
• Field of Search: 200/61.45 R-61.53, 73/514-520, 335/2
• US Class Current: 335/2
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence
• CPC Class Codes: G01P 15/11 by inductive pick-up
• 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 35/143 Resetting means

Abstract

A switch device which includes a magnet movable within a passageway. A wire coil is provided about the passageway such that, as the magnet moves into the coil, a current is induced, thereby providing a signal pulse. The switch can be utilized for sensing changes in inertia, with a stopper opposing movement of the magnet unless the magnet imparts sufficient force against the spring biased stopper to allow the magnet to move along the passageway. The biasing force of the stopper can be adjusted to adjust the amount of force, acceleration or deceleration required for actuating the switch. The switch may also be utilized without the spring-biased stopper, with the magnet preloaded with a spring or weight, such that the switch automatically operates upon removal of a safety pin.

Claims

1. A switch comprising:

a housing including a passageway therein;

a magnet mounted within and movable along said passageway;

a stopping pin for preventing possible movement of said magnet until removed; and

a coil mounted in said housing such that is comprises a spiral around at least a portion of said passageway;

wherein movement of said magnet along said passageway and into said coil causes conduction of a current thereby producing a signal pulse.

2. The switch of claim 1, further including a means for applying a force to said magnet for causing said magnet to move along said passageway.

3. The switch of claim 2, wherein the means for applying a force includes a preloaded spring.

4. The switch of claim 2, wherein said housing contains a hole and a pin projects into said passageway through said hole to prevent movement of said magnet, and wherein removal of said pin from said passageway causes said means for applying a force to move said magnet along said passageway and at least partially inside of said coil.

5. The switch of claim 1, further including an access port in said housing to allow for resetting of said switch by permitting means for applying a force to said magnet in opposition to the direction of said movement such that after said movement, said magnet can be placed in a position occupied prior to said movement.

6. The switch of claim 1, further including magnetic shielding means for preventing an erroneous induction of current in said coil.

7. The switch of claim 1, further including an external magnet positioned outside the housing and relative to said movable magnet for repelling or attracting said movable magnet so as to reset said switch.

8. A switch comprising a housing including a passageway therein:

a magnet mounted within and movable along said passageway;

a coil mounted in said housing such that it comprises a spiral around at least a portion of said passageway; and

means for opposing movement of said magnet along said passageway unless said magnet exerts a predetermined amount of force upon said means for opposing movement, said means for opposing movement comprising a spring mounted stopper which at least partially projects into said passageway, and wherein a predetermined inertial force of said magnet causes said stopper to move in opposition to the spring bias to allow the magnet to move along said passageway and into said coil.

9. The switch of claim 8, further including means for adjusting said means for opposing movement to vary the predetermined amount of force.

10. The switch of claim 8, wherein said housing further includes a channel extending at least substantially perpendicular to said passageway, and the spring contacting said stopper is disposed in said channel, and wherein said stopper moves into said channel upon application of a sufficient force by said magnet.

11. The switch of claim 10, further including a threaded plug contacting said spring, wherein movement of said plug varies the predetermined amount of force.

12. The switch of claim 10, wherein a portion of said channel adjacent to said passageway has a reduced cross-section to prevent said stopper from excessively protruding into said passageway.

13. A switch for sensing changes in inertia comprising:

a housing having a passageway therein;

a mass disposed within and movable along said passageway;

a restraint extending at least partially into said passageway for restraining movement of said mass unless said mass exerts at least a predetermined amount of force upon said restraint comprising a stopper which is spring biased into a position at least partially extending into said passageway;

said housing further including a channel at least substantially perpendicular to said passageway, wherein the spring for biasing said stopper is disposed within said channel, and wherein a portion of said channel adjacent to said passageway has a reduced cross-section to prevent excessive protrusion of said stopper into said passageway.

14. The switch of claim 13, further including means for adjusting the predetermined amount of force required for said mass to overcome said restraint.

15. The switch of claim 14, wherein said means for adjusting includes a threaded plug which contacts a spring, said spring contacting said restraint, and wherein rotation of said plug causes movement of at least a portion of said spring thereby varying the amount of force required for said mass to move said restraint in opposition to the spring.

16. The switch of claim 14, further including means for varying a biasing force of said stopper.

17. The switch of claim 15 wherein said mass includes one of a magnet and a magnetic material, the switch further including a magnet external to said housing and relative to said movable magnet for repelling or attracting said mass so as to reset said switch.

18. The switch of claim 13, wherein said mass is a magnet.

19. A switch for sensing changes in inertia comprising:

a housing having a passageway therein;

a stopper which is spring biased to at least partially extend into said passageway;

a magnet disposed within said passageway and movable along said passageway only upon application of a sufficient force by setting said magnet upon said stopper;

a coil disposed such that it forms a spiral around a portion of said passageway such that as said magnet moves along said passageway a current is induced in said coil; and

a channel extending at least substantially perpendicular to said passageway, and wherein the spring for biasing said stopper disposed in said channel.

20. The switch of claim 19, wherein a plug is provided at one end of said channel to allow access to said channel, spring and stopper.

21. The switch of claim 20, wherein another end of sad channel has a reduced cross-section to prevent excessive protrusion of said stopper into said passageway.

22. The switch of claim 19, wherein a port is provided at one end of said passageway to allow for resetting of said switch.

23. The switch of claim 19, further including a hole capable of housing a removable pin projecting through said hole and into said passageway for preventing actuation of the switch.

24. The switch of claim 19, further including at least one port extending into said housing to prevent differential pressure forces as said magnet moves along said passageway.

25. The switch of claim 19, further including an adjusting device to vary the sufficient force required for movement of said magnet along said passageway.