Inertia or gravity responsive tilt switch

• US 5,457,293 A
• Filed: 05/23/1994
• Issued: 10/10/1995
• Est. Priority Date: 05/23/1994
• Status: Expired due to Fees

• Current Assignee: American Vehicular Sciences LLC (Acacia Research Corporation)
• Original Assignee: Automotive Technologies International Incorporated
• Inventors: Breed, David S.
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US08/247,759
• Time in Patent Office: 505 Days
• Field of Search: 200/61.45R-61.53, 200/61.45 M, 200/61.83, 200/DIG. 29, 200/262, 335/151-154, 335/61.53, 335/61.45 M, 335/61.83, 335/DIG.29, 218/91
• US Class Current: 200/61.52
• CPC Class Codes: H01H 35/147 the switch being of the reed switch type
• CPC Class Codes: Y10S 200/29 Ball

Abstract

A unique geometry is used to amplify the force created by gravity on a tilting mass to substantially increase the resulting contact force in a mechanical tilt switch. In some cases a novel contact surface containing abrasive particles is also used to substantially reduce the contact force required to achieve a low contact resistance. The combination of these two features permits a substantial reduction in the size of the seismic mass needed for mechanical tilt switches and results in a switch which has a comparable size and comparable performance to mercury switches without the use of mercury. In some applications the effect of vibration is reduced by partially filling the switch housing with a damping fluid.

Claims

1. A tilt switch comprising:

a housing;

a beam flexibly attached to and substantially within said housing;

said beam having a length substantially greater than its width or thickness;

a first contact within said housing attached to said beam, said contact having a portion at an angle with respect to said length, said portion of said contact having a first contact surface;

a mass within said housing positioned to apply an actuation force on and in the direction of motion of said beam, said actuation force resulting from gravity acting on said mass when said housing is tilted at an angle exceeding a predetermined actuation angle;

a second contact within said housing, said second contact having a second contact surface;

stop means to limit the motion of said beam when said housing is at a second predetermined angle less than the vertical,

and wherein

said tilting of said housing causes said beam to move causing said first contact surface to engage said second contact surface with a contact engagement force; and

said contact engagement force during contact of both said surfaces exceeds said actuation force.

2. The invention in accordance with claim 1 wherein said engagement force is at least twice as great as said actuation force.

3. The invention in accordance with claim 1 wherein said beam flexible attachment comprises a hinge.

4. The invention in accordance with claim 1 wherein said beam is flexible along its length.

5. The invention in accordance with claim 1 wherein said housing comprises an hermetically sealed glass enclosure.

6. The invention in accordance with claim 1 wherein said mass is attached to said beam.

7. The invention in accordance with claim 1 wherein said mass is separately supported and adjacent to said beam.

8. The invention in accordance with claim 1 wherein said housing comprises a sealed plastic enclosure.

9. The invention in accordance with claim 1 wherein said contact surface of at least one of the contacts is coated with a coating comprising an abrasive and a conductive matrix.

10. The invention in accordance with claim 1 wherein said mass is spherical and is movable on said beam substantially along said length.

11. The invention in accordance with claim 1 wherein at least one of said contacts comprises a snap action means.

12. The invention in accordance with claim 1 wherein said mass is made from a material which is at least twice as dense as steel.

13. The invention of claim 1 wherein said second contact is a portion of said housing.

14. The invention in accordance to claim 1 further comprising:

a liquid substantially filling said housing, said liquid exerting a force opposing motion of said first contact

and wherein

said switch is thereby made resistant to the effects of vibration.

15. The invention in accordance with claim 14 wherein said damping liquid is an oil.

16. The invention in accordance with claim 14 wherein said damping liquid is a silicone oil.

17. The invention in accordance with claim 14 wherein said damping liquid is a transformer fluid.

18. The invention in accordance with claim 14 wherein said switch is a tilt switch.

19. A tilt switch comprising:

a housing;

a first contact mounted within said housing, said contact having a first contact surface, said surface having a coating, said coating comprising abrasive particles and a conductive matrix;

a second contact mounted within said housing and spaced apart from said first contact; and

means to cause said first contact surface to engage said second contact;

and wherein

said coating results in a substantially less contact resistance than without said coating.

20. The invention in accordance with claim 19 wherein said abrasive particles are diamonds.

21. The invention in accordance with claim 19 wherein said abrasive particles are silicon carbide.

22. The invention in accordance with claim 19 wherein said conductive matrix is gold.

23. A reed switch comprising:

a housing;

a first contact mounted within said housing, said contact having a first contact surface, said surface having a coating, said coating comprising abrasive particles and a conductive matrix;

a second mounted within said housing and spaced apart from said first contact;

and,

means to come said first contact surface to engage said second contact.

24. The invention in accordance with claim 23 wherein said abrasive particles are diamonds.

25. The invention in accordance with claim 23 wherein said abrasive particles are silicon carbide.

26. A reed tilt switch comprising:

an hermetically sealed glass housing;

a beam flexibly attached to and substantially within said glass housing, said beam rotatably movable within said glass housing;

a first contact within said glass housing and attached to said beam, said contact having a first contact surface;

a mass within said glass housing positioned to apply an actuation force on and in the direction of rotation of said beam, said force resulting from gravity acting on said mass when said glass housing is tilted at an angle exceeding a predetermined actuation angle;

a second contact within said glass housing, said second contact having a second contact surface, said second contact surface positioned to engage said first contact surface with an engagement force when said glass housing is tilted at an angle greater than said actuation angle; and

stop means to limit the motion of said beam when said housing is at an angle less than the vertical;

and wherein

said contact engagement force during engagement of both said contact surfaces exceeds said actuation force.

27. The invention in accordance with claim 26 wherein said mass is made from a material which is at least twice as dense as steel.

28. A rolling ball tilt switch comprising:

a housing;

a beam flexibly attached to and substantially within said housing, said beam rotatably movable within said housing;

a first contact within said housing, said contact having a first contact surface, said surface having a coating, said coating comprising abrasive particles and a conductive matrix;

a ball within said housing positioned to roll on and apply an actuation force on and in the direction of rotation of said beam, said force resulting from gravity acting on said ball when said housing is tilted at an angle exceeding a predetermined actuation angle; and

a second contact within said housing, said contact having a second contact surface, said surface positioned to engage said first contact surface with an engagement force when said housing is tilted at an angle greater than said actuation angle.

29. A rolling ball tilt switch comprising:

a housing;

a beam attached to and substantially within said housing, said beam adapted to rotate within said housing;

a first contact within said housing and integral with to said beam;

a ball within said housing positioned to roll and apply an actuation force on and in the direction of rotation of said beam said force resulting from gravity acting on said ball when said housing is tilted at an angle exceeding a predetermined actuation angle;

a second contact within said housing positioned to engage said first contact with an engagement force when said housing is tilted at an angle greater than said actuation angle; and

,

mechanical advantage means to cause said contact engagement force to exceed said actuation force.

30. A tilt switch comprising:

a housing;

a beam flexibly attached to and substantially within said housing;

said beam having a length substantially greater than its width or thickness;

a first contact within said housing attached to said beam, said contact having a portion at an angle with respect to said length, said portion of said contact having a first contact surface;

a mass within said housing positioned to apply an actuation force on and in the direction of motion of said beam said actuation force resulting from gravity acting on said mass which contacts said beam when said housing is tilted at an angle exceeding a predetermined actuation angle;

a second contact within said housing, said second contact having a second contact surface;

stop means to limit the motion of said mass when said housing is at a second predetermined angle less than the vertical, and wherein

said tilting of said housing causing said mass to rotatably move which causes said first contact surface to engage said second contact surface with a contact engagement force; and

said contact engagement force during contact of both said surfaces exceeds said actuation force.

31. A tilt switch comprising:

a housing;

a beam flexibly attached to and substantially within said housing, said beam having a length substantially greater than its width or thickness;

a first contact within said housing attached to said beam, said contact having at least one portion at an angle with respect to said length, said portion of said contact having a first contact surface;

a mass within said housing positioned to apply an actuation force on and in the direction of motion of said beam, said actuation force resulting from gravity acting on said mass when said housing is tilted at an angle exceeding a first predetermined actuation angle in a first direction or at an angle exceeding a second predetermined actuation angle in the direction opposite to said first direction;

a second contact within said housing, said second contact having a second contact surface, said second contact located in said first direction;

a third contact within said housing, said third contact having a third contact surface, said third contact located in the direction opposite to said first direction;

and wherein

said tilting of said housing in said first direction at an angle exceeding a first predetermined actuation angle causing said beam to move in said first direction causes said first contact surface to engage said second contact surface with a first contact engagement force;

and said tilting of said housing in said second direction at an angle exceeding a second predetermined actuation angle causing said beam to move in said direction opposite to said first direction causes said first contact surface to engage said third contact surface with a second contact engagement force; and

said first contact engagement force during engagement of said first and second contact surfaces exceeds said actuation force, and

said second contact engagement force during engagement of said first and third contact surfaces exceeds said actuation force.

32. A tilt switch comprising:

a housing;

a beam flexibly attached to and substantially within said housing, said beam having a length substantially greater than its width or thickness;

a first contact within said housing attached to said beam, said contact having a first contact surface;

a mass within said housing, said mass attached to said first contact means, said first contact surface being closer to where said beam is flexibly attached to said housing than said mass;

a second contact within said housing, said second contact having a second contact surface;

said mass positioned to apply an actuation force on and in the direction of motion of said beam, said actuation force resulting from gravity acting on said mass when said housing is tilted at an angle exceeding a predetermined actuation angle;

said tilting of said housing causing said beam to move causes said first contact surface to engage said second contact surface with a contact engagement force; and

said contact engagement force during contact of both said surfaces exceeds said actuation force.