Gravity switch

• US 4,513,183 A
• Filed: 04/30/1984
• Issued: 04/23/1985
• Est. Priority Date: 05/04/1983
• Status: Expired due to Term

• Current Assignee: Plastics Incorporated (NSI Holdings, Inc.)
• Original Assignee: Plastics Incorporated (NSI Holdings, Inc.)
• Inventors: Hill, Clinton W.
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US06/605,036
• Time in Patent Office: 358 Days
• Field of Search: 200/61.45 R, 200/61.45 M, 200/61.52, 200/61.83, 200/DIG. 29, 200/267
• US Class Current: 200/61.45R
• CPC Class Codes: H01H 35/02 Switches operated by change of position, inclination or orientation of the switch itself in relation to gravitational field tilting mercury container H01H29/20; change of position due to change of liquid level H01H35/18
• CPC Class Codes: Y10S 200/29 Ball

Abstract

A gravity switch comprises a dielectric and a cup-shaped conductor pressed together in telescoping relationship to provide a hermetically sealed enclosure for a brass ball contact member rollable axially therein for selectively making or breaking an electrical contact between the sidewalls of the cup-shaped conductor and a point contact with a second conductor extending through the dielectric. The diameter of the ball is only slightly less than the diameter of the enclosure and is more than half the axial distance between the closed end of the cup-shaped conductor and the point contact of the second conductor in order to constrain the ball movement and reduce contact bounce. The various contact surfaces of the switch are silver plated and thoroughly cleansed to optimize current flow and maximize switch life within the hermetically sealed enclosure.

Claims

1. A gravity switch comprising:

(A) a cylindrical shell member of conductive material closed at one end and open at the other end;

(B) a base member of dielectric material closing the open end of said shell member;

(C) an electrical contact extending axially through said base member to present a contact tip surface located adjacent the open end of the said shell member on the central axis of that member;

(D) a ball of conductive material positioned rollably within said shell member and having a diameter which is slightly less than the inner diameter of said shell member and more than half of the shortest distance between said contact tip surface and the inner surface of the closed end of said shell member;

(E) said shell member and electrical contact cooperating with said base member for hermetrically sealing the interior of said shell member within which said ball is rollable;

(F) said ball having a surface coating of conductive material different from the interior material of said ball; and

(G) said contact tip surface and the interior surface of said shell contactable by said ball comprising material having electrical properties comparable to the electrical properties of the material coating said ball.

2. A gravity switch according to claim 1, wherein said contact tip surface comprises a spherical surface having a radius comparable to the radius of said ball so as to make a tangent point electrical contact with said ball.

3. A gravity switch according to claim 1, wherein said conductive material is a precious metal.

4. A gravity switch according to claim 3, wherein said precious metal is silver.

5. A gravity switch according to claim 4, wherein said contact tip surface comprises a spherical surface having a radius comparable to the radius of said ball so as to make a tangent point electrical contact with said ball.

6. A gravity switch according to claim 1, wherein the material of said ball is brass.

7. A gravity switch according to claim 6, wherein said contact tip surface comprises a spherical surface having a radius comparable to the radius of said ball so as to make a tangent point electrical contact with said ball.

8. A gravity switch according to claim 6, wherein said conductive material is a precious metal.

9. A gravity switch according to claim 8, wherein said precious metal is silver, and said contact tip surface comprises a spherical surface having a radius comparable to the radius of said ball so as to make a tangent point electrical contact with said ball.

10. A gravity switch according to claim 8, said base member having an annular flange extending coaxially into the open end of said shell member and having an annular shoulder around said flange, the radial dimension of said shoulder approximating the wall thickness of said shell member, whereby said shell member may be hermetically telescoped over said annular flange portion to position its open end adjacent to said shoulder and define a smooth air-tight switch capsule having a uniform external diameter throughout its length corresponding to that of the shell member.

11. A gravity switch for opening or closing an electrical circuit in accordance with the inclination of the axis of the switch from a horizontal position comprising a cup-shaped dielectric member having axially extending sidewalls forming an enclosure, a base closing one axial end of said enclosure, and a mouth opening axially endwise at the opposite axial end of said enclosure;

first contact means of electrical conducting material comprising an interior electrical contact within said enclosure adjacent to said base, an exterior electrical contact externally of said enclosure, and means extending through said member and electrically connecting said interior and exterior contacts;

second contact means of electrical conducting material spaced from the first contact means and fixed with respect to said enclosure, said second contact means having guide portions extending axially along said sidewalls in the direction from said base toward said mouth and effecting an interference fit with said sidewalls, said guide portions terminating in said direction in portions closing said mouth and defining a second exterior contact; and

means for selectively completing an electrical connection between said guide portions and said interior contact comprising gravity actuated contact means movable axially along said guide portions in electrical contact therewith to and from positions of electrical contact with said interior contact in accordance with the inclination of said axis, said gravity actuated contact means comprising a ball rollable within said enclosure, said exterior contact comprising fixed means for effecting a point contact with said ball when the latter is in said position of electrical contact with said interior contact, said first and second contact means cooperating with said dielectric member for hermetrically sealing said enclosure, said ball having a surface coating of conductive material different from the interior material of said ball, the surfaces of said fixed means and said guide portions comprising material having electrical properties comparable to the electrical properties of the material coating said ball.

12. A gravity switch according to claim 11, wherein said surface coating is a precious metal.

13. A gravity switch according to claim 12, wherein said contact tip surface comprises a spherical surface having a radius comparable to the radius of said ball so as to make a tangent point electrical contact with said ball, and said precious metal is silver.

14. A gravity switch according to claim 11, wherein the material of said ball is brass.

15. A gravity switch according to claim 14, wherein said contact tip surface comprises a spherical surface having a radius comparable to the radius of said ball so as to make a tangent point electrical contact with said ball, and said surface coating is silver.