US3368051A - Switch construction - Google Patents

Description

B. J. GOLBECK SWITCH CONSTRUCTION Filed Oct. 18, 1966 Feb. 6, 1968 United States Patent 3,368,051 SWHTCH CONSTRUCTION Bernard J. Golbeck, Crystal Lake, IllL, assignor to Oak Electro/Netics Corporation, a corporation of Delaware Filed Oct. 18, 1366, Ser. No. 587,475 3 Claims. (Cl. 200-166) ABSTRACT OF THE DISCLOSURE A wiper contact mounting for use in an electric switch in which a contact carrying member of insulating material has contacts mounted in back-to-back pairs on opposite sides of the member. The contacts each have a body portion on the member with an aperture aligned with an aperture in the member and a metallic rivet extends through the apertures securing the contacts to the member. The aperture in one of the contacts is larger than the aligned aperture in the member and an insulating block is disposed between the one contact and the rivet with an aperture aligned with the aligned apertures in the contact and the member. The rivet passes through the aligned apertures to maintain the contacts and insulating block rigidly on the member. The block includes a boss completely surrounding the rivet and extending into the enlarged aperture of the one contact to maintain the contact spaced from the rivet and reduce arcing between the contact and the rivet. The boss is substantially the same thickness as the one contact so that the insulating block holds the contacts securely against the member.

Background of the invention It is often desirable to construct a switch in which its contacts are mounted in a back-to-back relation on an insulating sheet, but electrically isolated. It is common to secure contacts to an insulating sheet by a rivet which extends through a hole in the sheet. Such a mounting pre sents a problem where the contacts are to be electrically isolated. Allison Patent 2,128,279 shows a construction in which an insulating block is provided under one end of the rivet to space it from one of the contacts. The mounting hole in the contact is larger than the rivet so that it can be spaced therefrom. The edges of the insulating block bear against upturned surfaces of the contact to establish a desired relative position. With the Allison construction, however, it is dificult to maintain proper spacing between the rivet and contact as the switch contact is easily deformed and as a result the contact may shift relative to the rivet and cause low voltage breakdown or a short circuit.

Summary of the invention A primary object of this invention is to provide a new and useful contact assembly.

Another object of this invention is to provide a new and useful mounting for electrical contacts.

Still a further object is to provide a simple contact carrying stator construction which will permit contacts insulated from each other to be supported in pairs on opposite sides of the stator by a mounting means which includes metallic means engaging one contact and passing through the stator and other contact and an insulating block disposed above the other contact to position said other contact so that it is spaced from said metallic means to insure that the contacts of each pair are electrically separate and also to prevent arcing between the other contact and the metallic means.

Other objects and advantages of the invention will become readily apparent from the following detailed description taken in connection with the accompanying drawings.

3,3fi8,5i Patented Feb. 6, 1968 Description of the drawings FIGURE 1 is a plan view of a gang switch construction embodying the invention;

FIGURE 2 is a partial section taken generally along the line 22 of FIGURE 1;

FIGURE 3 is a perspective view of an insulating block used in the switch construction and embodying the invention;

FIGURE 4 is a plan view of a modified insulating block having a single aperture;

FIGURE 5 is an elevation view of the insulating block of FIGURE 4; and

FIGURE 6 is a partial section, similar to FIGURE 2, including two insulating blocks.

Detailed description of the invention The rotary switch section shown in FIGURE 1 comprises a flat stator 10 of rigid insulating material having a plurality of pairs of apertures 12 disposed in a circle about the stator. The stator 10 is generally circular and has protruding ear portions 14 on opposite sides thereof with mounting apertures 16 through each car so that a plurality of sections may be mounted in ganged relation.

At one or more of the pair of apertures 12 two contacts, generally designated 18 and 19, may be mounted as shown in FIGURE 2. Contact 19, below stator 10 in FIGURE 2, has a double wipe construction, with a bent over strip of metal forming a connecting portion 20, a mounting body portion 22 and contacting jaws 24a, 24b. Jaw 24b extends upwardly into a recess 26 formed in the stator plate 10. The body portion 22 is provided with a pair of apertures 29 aligned with and substantially the same size as stator apertures 12.

Rivets 30 engage contact 19 and pass upwardly through its apertures 29 and stator apertures 12 to retain contact 19 in position. In the event that single rivets are used in smaller switch constructions, the upwardly bent jaw 24b extending into recess 26 in the stator 10 retains the contact 19 in position against rotary movement about the rivet.

Positioned above stat-or plate 10 is the second contact 18 which is generally similar in construction to contact 19, having an outer connecting portion 32, a mounting body portion 34 and jaws 36a, 36b. The jaw 36a of contact 18 similarly extends into a recess 38 on top of the stator to retain contact 18 in position against rotary movement in the event a single rivet is employed in smaller switches. The body portion 34 has a pair of apertures 39 (or a single elongated slot as illustrated herein) which are larger than the rivets 30 and stator apertures 12, so that contact 18 may be physically spaced and electrically separate from the rivets which engage contact 19.

To maintain the upper contact 18 in a spaced relationship with respect to the metallic rivets 30, an insulating block 40 (shown in perspective in FIGURE 3) is provided. This block has apertures 42 through which rivets 39 pass and in which they snugly fit. The insulating block includes a rib or boss -44 which extends through the enlarged aperture 39 of contact 18 completely surrounding rivets 30 to position contact 18 spaced from rivet 30 thereby electrically insulating contact 18 from contact 12. The rib or boss 44 centers the rivets 30 in the apertures and substantially reduces arcing between contact 18 and the rivets 30 which are electrically engaged with contact 19.

In the embodiment of the invention illustrated, cooperating with the stator contacts 18, 19 is a flat insulating rotor 45 centrally disposed thereof. A plurality of flat segmental contacts 46 are carried on opposite sides of rotor 45 about the outer periphery thereof for selectively making contact with surfaces 28a, 28b and 38a, 38b

of contacts 19 and 18, respectively. A contact extension 43 (FIGURE 1) is disposed at the outer edge of each segmental contact 46. The extension 48 may be of any angular extent and may be provided in any number or even omitted. This extension 48 is adapted to engage the jaws of short contacts (18a in FIGURE 1, for instance), while the remainder of segmental contacts 46 engage longer contacts 18b (FIGURE 1) in a known manner such that a number of circuits may be simultaneously acted upon as the rotor 45 is rotated. In the embodiment of the invention illustrated, since the contacts 18 and 19 of each pair thereof are electrically insulated from each other on opposite sides of the stator and there being two segmental contacts 46, four circuits may be acted upon by the movement of the single rotor 45.

FIGURES 4 and 5 show a modified insulating block 50 similar to the insulating block 40 but has a single aperture through which a single rivet passes for use in smaller switch constructions. This insulating block also has a rib or boss 52 which extends through an enlarged aperture of an appropriate upper contact similar to contact 18 but having a single aperture therethrough. The block 50 similarly centers the rivet passing therethrough to maintain the contact spaced from the rivet and substantially reduces arcing between the contact and rivet.

FIGURE 6 shows a form of the invention wherein a second insulating block 54 is provided between contact 19 and rivets 30. Block 54 is similar to block 40 and includes a rib or boss 56 which extends through an enlarged aperture 29' of contact 19 completely surrounding rivets 30 to position contact 19 spaced from rivets 30 and substantially reducing arcing therebetween. Occasionally it is desirable to attain a higher voltage breakdown, and this can be accomplished by employing two insulating blocks whereby both contacts are insulated from rivets 30.

In addition to the Allison patent discussed above, other methods of electrically insulating the contacts in each pair, such as providing a laminated stator, have proven expensive to manufacture. Such laminated stators require more pieces and require notches to accommodate the rivet heads. The provision of an insulating block as employed herein has proven to be a satisfactory and efficient means for electrically insulating back-to-back contacts. But heretofore an extra means had to beprovided to position the one contact (18, for instance) such that its body portion bounding its enlarged aperture is spaced from the rivets. Not only does the rib or boss 44 (56) eliminate any extra positioning means, but it reduces arcing between the contact 18 (and/or 19) and rivets 30.

The foregoing detailed description is given for clearness of understanding only and no unnecessary limitations are to be understood therefrom, as some modifications will be obvious to those skilled in the art.

I claim:

'1. In an electric switch having a contact carrying member of insulating material with contacts mounted in backto-back pairs on said member, one contact being on one side of said member and the other contact being on the other side thereof, said contacts each having a connecting portion, a body portion disposed on said member with an aperture aligned with an aperture in said member and a contacting portion, the aperture in said one contact being larger than the aligned aperture in said member, and metallic means securing the contacts to said member, the improvement comprising an insulating block disposed between said one contact and said metallic means and having an aperture aligned with said aligned apertures in said contact and said member, said metallic means passing through the aligned apertures in said one contact and said member to maintain said contacts and insulating block rigidly on said member, and said insulating block including a boss completely surrounding said metallic means and extending into the enlarged aperture of said one contact to maintain said one contact spaced from said metallic means and to reduce arcing between said one contact and said metallic means, said boss being substantially the same thickness as said one contact so that said insulating block holds said one contact securely against said member.

2. The electric switch of claim 1 wherein the periphery of said boss is tapered inwardly to facilitate insertion into the aperture of said one contact.

3. The electric switch of claim 1 wherein the body portion of each of said contacts includes a pair of apertures aligned with a pair of apertures in said member, the apertures in said one contact being larger than the aligned apertures in said member, metallic means engaging said other contact and passing through the pair of aligned apertures in said one contact and said member to maintain said contacts and insulating block rigidly on said member, and said insulating block including a rib completely surrounding said metallic means and extending into the enlarged apertures of said one contact, said rib being substantially the same thickness as said one contact.

References Cited UNITED STATES PATENTS 2,128,279 8/1938 Allison 200-11 2,990,465 6/1961 Dumke et al. 200--166 FOREIGN PATENTS 1,085,750 2/1955 France.

ROBERT K. SCHAEFER, Primary Examiner.

.H. O. JONES, Assistant Examiner.

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