US3555219A

US3555219A - Tilt switch

Info

Publication number: US3555219A
Application number: US830360A
Authority: US
Inventors: Wade M Johnson; Harry L Mussett
Original assignee: Continental Oil Co
Current assignee: ConocoPhillips Co
Priority date: 1969-06-04
Filing date: 1969-06-04
Publication date: 1971-01-12
Anticipated expiration: 1988-01-12
Also published as: FR2112780A5; DE2050710A1

Abstract

A tilt-sensitive electrical mercury switch wherein the mercury chamber comprises upper and lower spaced walls of essentially conical shape having the cone apexes oriented downward and the two-cone bases joined at their peripheries to form a fluid-tight chamber; various embodiments for restricting splashing of the mercury are provided.

Description

United States Patent Wade M. Johnson;

Harry L. Mussett, Ponca City, Okla. 830,360

June 4, 1969 Jan. 12, 197 l Contnental Oil Company Ponca City, Okla.

a corporation of Delaware [72] Inventors [21 App] No, [22 Filed [45] Patented [73] Assignee [54] TILT SWITCH 1,618,608 2/1927 Smith ZOO/61.47 1,858,191 5/1932 ZOO/61.47 2,130,500 9/1938 ZOO/61.47 2,056,877 10/1936 ZOO/61.47 2,161,411 6/1939 Erich 200/61.47 2,192,262 3/1940 Griesedieck ZOO/152.7 2,522,721 9/1950 Matterrl 200/152 3,036,296 5/1962 Conte 200/61.47X 3,163,726 12/1964 Kalish et a1. 200/61.47X

Primary Examiner-Robert K. Schaefer Assistant Examiner-M. Ginsburg Att0rneys.loseph C. Kotarski, Henry H. Huth, Jerry B. Peterson, William A. Mikesell, Jr. and Carroll Palmer ABSTRACT: A tilt-sensitive electrical mercury switch wherein the mercury chamber comprises upper and lower spaced walls of essentially conical shape having the cone apexes oriented downward and the two-cone bases joined at their peripheries to form a fluid-tight chamber; various embodiments for restricting splashing of the mercury are provided.

ATENTED JAN 1 21am FIG.

FIG. 4

FIG. 3

INVENTORS. WADE M. JOHNSON HARRY L. MUSSETT' BY I "L-22 3mm C 724% ad! g1 ATTORNEY TILT SWITCH This invention relates to a novel tilt-sensitive electrical mercury switch configuration.

Tilt-sensitive switches comprising a chamber containing a pool of mercury which opens or closes an electrical circuit between a pair of elecrodes upon appropriate tilting have long been known. One problem existing with such switches has been their sensitivity to vibration, i.e. when rigidly mounted on a motor vehicle or other equipment subject to vibration, the mercury can splash and thus open or close a circuit erroneously when the switch has not been subjected to the necessary tilting.

It is accordingly an object of this invention to provide a mercury switch wherein the tendency of the mercury pool to splash when its chamber is subjected to vibration or jogging is diminished. Another object of the invention is to provide a mercury switch sensitive to actuation by tilting in any direction.

Other objects and the several advantages of this invention will become apparent upon study of this disclosure, the appended claims, and the drawing, in which:

FIGS. 14 represent vertical cross-sectional views of various embodiments of the invention.

Referring now to the drawing, and to FIG. 1 in particular, a chamber indicated generally as contains a pool of mercury 11 and two or more electrodes 12. According to the present invention, chamber 10 comprises an'upper wall 13 and a lower wall 14, both generally conical in configuration.

Walls

13 and 14 are spaced apart sufficient to permit free flow of mercury therebetween, i.e. to avoid surface tension effects. The downwardly oriented apex of lower wall 14 is preferably rounded, as shown, so as not to present crevices or sharp corners which would by surface tension impede the free movement of mercury 11. In the embodiment of this FlG., the apex of upper wall 13 is convex upwardly at a distance from lower wall 14 as to conform to or just clear the upper surface of mercury 11. Upper wall 13 and lower wall 14 are joined together at the peripheries of their bases, i.e. at their upper ends, so as to make chamber 10 fluid-tight, preferably so as to present a smooth or rounded inner surface as shown. Electrodes 12 are suitably sealed where they pass through the walls of chamber 10, as at 15. In this embodiment, one electrode 12 enters the chamber through upper wall 13, and another through lower wall 14. When a normally closed switch is desired, the inner ends of both electrodes 12 terminate within the body of liquid mercury 11, preferably near the center thereof, with the mercury in its normal position between the apexes of the walls.

Referring now to FIG. 2, this embodiment differs from that of FIG. 1 in that the resistance to mercury-splashing is provided by the shape of lower wall 14, rather than by the convex apex of upper wall 13. Lower wall 14 in the present embodiment is provided with a necked-in portion 16, which is so spaced from upper wall 13 as to resist splashing of a large portion of the mercury therebetween but to permit free flow upon tipping of chamber 10 about its vertical axis. Necked-in portion 16 also provides a quick, clean break" of contact between the electrodes upon tipping when the mercury has cleared the hump provided thereby. In this embodiment, both electrodes 12 enter chamber 10 through lower wall 14.

In the embodiment of FIG. 3, both upper wall 13 and lower wall 14 are of generally conical with smoothed apex portions, and resistance to splashing of the mercury is provided by a also illustrates an embodiment of electrodes l2 wherein one electrode 12 terminates within chamber 10 in theform of a ring surrounding and spaced from the inner end of the other electrode 12. This FIG. further illustrates and electrode 12', here a circular ring, spaced some distance above the normal upper surface of mercury 11 and suitably connected to an external circuit by a conductor and seal means not shown. Electrode 12' is used in conjunction with an electrode 12 to provide a normally open switch action, and chamber 10 must obviously contain sufficient mercury to provide a circuit between these electrodes when in a tipped position.

The inclination of wall 14 with respect to the vertical axis of the switch obviously controls the amount of tilt necessary to actuate the switch and, because of the symmetry about its vertical axis, the switch is actuable by tilting in any direction from the vertical.

Chamber 10 can be fabricated in one or more pieces, and can be made of insulating material such as glass or any number of plastics, the primary requirement being that mercury does not amalgamate with the chamber wall. The electrodes are made of suitable electrically conductive material which preferably does not amalgamate. Although any electrically conductive liquid can be used in the chamber, mercury is far preferred because of its high specific gravity and resistance to electrolysis.

Various features shown in the FIGS. can obviously be interchanged and combined with those of other FIGS. For example, restriction screen 17 of FIG. 3 can be used in conjunction with the electrodes configuration of FIG. 2, etc.

Although this invention has been described with respect to particular embodiments thereof, it is not to be so limited, as changes and modifications may be made therein which are within the spirit and scope of the invention as defined by the appended claims.

We claim:

1. Tilt-actuable electrical switch means comprising a chamber means defined by spaced inner and outer wall means of generally conical configuration, said wall means being joined at their peripheries, electrically conductive liquid within said chamber means, electrode means terminating within said chamber means, and motion restriction means comprising a convexity of said inner wall means at the apex thereof toward the base thereof, the space between said motion restriction means and said outer wall means being substantially filled by said electrically conductive liquid.

2. The device of claim 1 wherein said electrode means comprises coaxial conductor means having insulating means in an annular space thereof.

3. The device of claim 1 wherein said electrode means comprises a first substantially linear conductor means and a second conductor means terminating in a ring adjacent to and spaced from the end of said first conductor means.