US2566704A

US2566704A - Electric switch

Info

Publication number: US2566704A
Application number: US77526A
Authority: US
Inventors: William E Leibing
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-02-21
Filing date: 1949-02-21
Publication date: 1951-09-04
Anticipated expiration: 1968-09-04

Description

W. E. LEIBING ELECTRIC SWITCH Sept. 4, 1951 Filed Feb. 21. 1949 6, w W M T a m Em W my w M M Patented Sept. 4, 1951 UNITED STATES PATENT OFFICE ELECTRIC SWITCH William E. Leibing, Los Angeles, Calif. Application February 21, 1949, Serial No. 77,526

3 Claims.

This invention relates to electric switching apparatus and is particularly directed to improvements in switch construction utilizing separable contacts positioned in a chemically inert medium.

Electrical make and break switches which are required to carry any considerable amount of current are commonly subject to deterioration of the contact points, particularly when the points are open to the atmosphere. The rapid deterioration of contact points due to arcing in such switches has led to the use of relays operating in conjunction with the switches to make and break the required current flow. For example, automobile horns are now commonly actuated through a relay which is in turn energized from a manually operable switch carrying very low current.

It is the principal object of this invention to provide an electrical switch capable of carrying relatively high current without being subject to destruction of contacts through arcing. The added expense of supplying and installing a relay in conjunction with the manual switch is thereby eliminated.

Another object is to provide an electrical switch having contacts positioned within an inert medium so that oxidation of the contact points under arcing conditions is eliminated.

Another object is to provide a switch of this type in which an inner gas surrounds the contact points and acts on a flexible impervious diaphragm for resiliently maintaining the contacts in spaced position.

Other and more detailed objects will appear hereinafter.

In the drawings:

Figure 1 is a sectional elevation partly broken away showing a preferred embodiment of my invention and illustrating the switch contacts in spaced position.

Figure 2 is a view similar to Figure 1 showing the switch contacts in closed position.

Referring to the drawings, a two-part housing generally designated l includes a metallic shell II and an electrically nonconducting cover I2. The cover l2 may be formed of any suitable electrically nonconducting material. The two parts of the housing I0 are maintained in assembled relationship by means of a clamping ring I3 which encircles adjacent flanges I4 and I5 formed on the shell II and cover I2 respectively.

A flexible impervious diaphragm I6 is positioned within the housing I0. This diaphragm I6 is clamped on its outer rim between the flanges I4 and I5 and is thus held securely in place. The clamping ring I3 confines the outer rim of the diaphragm I6 under compression between the flanges I4 and I5.

The cover I2 may be provided with a central axially extending opening I8 which acts as a guide for the metallic plunger I9 extending through the opening into the interior of the housing I0. The plunger I9 is provided with an integral enlarged head 20 adapted to engage the central portion of the diaphragm IS. A metallic button or cap 2| is provided with a central projection 22 which extends into an axial recess 23 provided in the plunger I9. The projection 22 also extends through a central opening 24 provided in the diaphragm I6. The projection 22 is press-fitted into the recess 23 so that the central portion of the diaphragm I6 is clamped under compression between the head 20 and th button or cap 2|.

An inert gas such as, for example, nitrogen or argon, is admitted into the chamber I1 defined by the shell II and diaphragm I6. The gas is admitted through passage 25 which is subsequently closed by any suitable means such as, for example, by the lead plug 26. Pressure of the inert gas within the chamber II opposes atmospheric pressure within the cover I2 and normally maintains the plunger I9 in the position shown in Figure 1. On or more ports 21 may be formed in the cover I2 to admit atmospheric pressure into the interior of the cover I2.

Manual pressure exerted against the end 28 of the plunger l9 compresses the gas within the chamber I'I sufiiciently to bring the

contact faces

29 and 30 into engagement. These faces are formed as part of the metallic elements 2| and I I. An electrical lead Wire 3I may be electrically connected in any suitable way to the contact element 2|, and as shown in the drawings this electrical connection may take the form of an attaching screw 32 connecting the lead wire 3| with th metallic plunger I9. The electrical connection is then established through the metallic projection 22 to the movable switch contact 2|. The shell II may be connected electrically to the other lead which may take the form of a metallic bracket 33 grounded by means of an attachment bolt 34 connected to a supporting frame (not shown). The bracket 33 may be provided with an aperture 35 through which the threaded boss 36 extends. This boss 36 may be formed integrally with the shell Ii. A-clamping nut 31 serves to hold the bracket 33 in assembled relationship with respect to the housing I0. 7

An electrical connection is closed between the lead wire 3| and the ground ng belt it when the plunger 19 is manually mote-ii to bring the con tact surfac s 29 and 30 into engagement. When manual pressure is released from the end surface 28 the pressure of the inert gas within the chamber I! flexes the diaphragm IE to return the plunger to the open position shown in Figure 1 and thereby separate the

contact faces

29 and 30. Although arcing may occur when the contact surfaces are separated, no serious destructive efi'ects occur because oxygen is excluded from the chamber I! and hence oxidation cannot occur with arcing. The pressure of the inert gas is above atmospheric pressure so that the switch is normally open.

It is essential that the diaphragm l6 be substantially impervious so that the inert gas does not leak through the diaphragm out of the chamber I1. I have found that commercially available synthetic materials made by Du Pont de Nemours Company under the name Fairprene" 5002 or 5003, or Chicago Rawhide Company under the name of Servene" 8083 gives satisfactory results.

It will be understood from this description that the inert gas serves two purposes. It excludes oxygen from the contact points so that arcing is not objectionable and it acts against the diaphragm normally to maintain the switch contacts in open position.

In this specification and in the claims I have used the word inert" in connection with gases to designate gases which protect electrical contact points from excessive damage or decay under arcing conditions, and therefor inert gases as thus defined are not necessarily fully inert in the chemical sense.

The use of gas under compression to resiliently maintain the contact points in spaced relationship eliminates the requirement of a metallic spring, and hence the switch construction embodying my invention may be economically constructed in quantity and on a competitive basis to make and break switches which must be used in conjunction with relays to avoid pitting of contacts.

. My improved switch construction is particularly well suited for use in mines, powder maga-, zines, refineries and other locations where it is essential that make and break electric switches be protected so that arcing of contacts cannot cause an explosion. Since the contacts of my improved switch construction are mounted in an enclosed chamber, there is no possibility that arcing across the switch points might set fire to an explosive mixture in the atmosphere.

While in the drawings I have shown the construction which provides a stop for movement of the plunger in one direction only, it will be recognized that a stop for limiting the movement of the plunger in the other direction can be had if necessary or desirable. Such a stop could be conveniently mounted on the cover l2 and arthe details herein set forth, but my invention is of the full scope of the appended claims.

I claim:

1. In an electric switch construction, the comhination or a shell, a flexible diaphragm cooperating with the shell to form an enclosed chamber,-a stationary contact element on the shell, a movable contact element on th diaphragm, said contact elements being within said chamber, the chamber being filled with an inert gas under pressure, the pressure of the gas acting to move the diaphragm in a direction to hold the contact elements in spaced relationship, and manually operable means accessible exteriorly of the shell whereby the diaphragm may be moved against the pressure of the gas to engag the electrical contact elements.

2. In an electric switch construction, the combination of an electrically conducting shell, an electrically nonconducting cover fixed relative to the shell, a flexible diaphragm clamped between the cover and shell and cooperating with the shell to define an enclosed chamber, a stationary contact element on the shell, a movable contact element secured relative to the diaphragm, said contact elements being positioned within said chamber, an electrically conducting plunger fixed relative t the movable contact element and extending exteriorly of said cover, the chamber being filled with an inert gas under pressure, the pressure of the gas acting on the diaphragm to move the movable contact element away from the stationary contact element, the plunger being movably manually against the pressure of the gas to brin said elements into contact.

3. In an electric switch construction, the combination of an electrically conducting shell, an electrically nonconducting cover fixed relative to the shell and provided with a central opening, a flexible diaphragm, cooperating flanges on the cover and shell clamping the outer portion of the diaphragm therebetween, the diaphragm cooperating with the shell to define an enclosed chamber therebetween, a stationary contact element on the shell, a movable contact element secured'to the central portion of the diaphragm, said contact elements being positioned within said chamber, a plunger guided for axial movement within the central opening in the cover, the chamber being filled with an inert gas under pressure, the pressure of the gas acting on the diaphragm to move the movable contact element away from the stationary contact element, the plunger being movable manually against the pressure of the gas to bring said elements into engagement.

WILLIAM E. LEIBING.

REFERENCES CITED UNITED STATES PATENTS