US2862082A - Combined contact and terminal for electric switch - Google Patents

Description

COMBINED CONTACT AND TERMINAL FCR ELECTRIC SWITCH Filed Feb. 4. 1957 D. A. PIERCE Nov. 25, 1958 2 Sheets-Shun D. A. PIERCE Nov. 25, 1958 COMBINED CONTACT AND TERMINAL FOR ELECTRIC SWITCH 2 Sheets-Sheet 2 Filed Feb. 4, 1957 y mwgw 17m-152:7 Fzeraa United States Patent C)fi COMBINED CONTACT AND TERMINAL FOR i ELECTRIC SWITCH Donald A. Pierce, South Bend, Ind., assignor to Chicago Telephone Supply Corporation, Elkhart, Ind., a corporation of Indiana Application February 4, 1957, Serial No. 638,079

1 Claim. (Cl. 200-166) This invention relates to electric switches and refers more particularly to double-pole Single-throw switches of the type used in television and radio receivers, and often mounted upon the back of a variable resistor to be actuated concomitantly with` adjustment of the resistor through a fraction of its fullrange of adjustment.

Those familiar with the demands made by the manufacturers of television and radio receivers for smaller and smaller components, know that the switches with which this invention is concerned, not only must have long life and good low resistance contact engagement, but, in addition, must be extremely small in overall size.l In fact, these switches are now miniaturized to the extent that the housing in which the entire switch instrumentalities are located is substantially less than 3A in diameter, and but very slightly deeper than 1A. Obviously, therefore, any improvement which enables the switch manufacturer to better attain these objectives and requirements, constitutes an important advantage.

One of the sources of difficulty in switches of this kind heretofore available, was in the mounting of the stationary contacts, and the connection thereof to their external terminals. While these diiculties have been overcome to a large degree by the combined contact and terminal of Patent No. 2,671,841, issued March 9, 1954, the present invention provides an even better solution to the problem.

The purpose and object of this invention, therefore, is to provide an improved contact and terminal wherein exceptional strength and rigidity are combined with unprecedented compactness or small size.

Broadly, this objective is achieved by forming the combined contact and terminal as a T-shaped stamping uniformly arcuate in transverse cross section. As a result, the stem of the T-shaped stamping which provides the terminal is considerably stronger and more rigid against bending. ln addition, by virture of the arcuate formation of the stamping, the anchorage of the combined contact and terminal to the switch base is more secure.

With the above and other objects in View, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly dened by the appended claim, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claim.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

Figure l is a view partly in side elevation and partly in longitudinal section, of a combined variable resistor and switch, the switch being equipped with the combined contact and terminal of this invention;

j 2,862,082 Patented Nov. 25, 1958 ICC the plane of the line 2 2, illustrating the switch in its open condition; i Figure 3 is a view similar to Figure 2 but showing the switch closed; l

Figure `4 is a perspective view of the combined contact and terminal of this invention shown byitself and prior Figure 2 is a cross sectional view through Figure 1 on i to assembly to the base of a switch; t

Figures 5 and 6 are views similar to Figures 2 and 3, respectively, but illustrating the combined contact and terminal of this invention used in conjunction with a contactor different than the one shown in Figures 2 and 3; and

Figure 7 is a plan view of the combined contact and terminal in its flat developed form, and also illustrating the manner in which the unit is anchored to the switch base.

Referring now more particularly to the accompanying drawings, the numeral 5 designates generally a variable resistor of the type used in television and radio receivers, upon the back of which a switch 6 is mounted to be actuated concomitantly with adjustment of the resistor through a fraction of its full range of adjustment. Since the variable resistor, and for that matter the mechanism of the switch, form no part of this invention, these parts have not been illustrated in detail. Suflice it to say that the variable resistor includes a rotor or contactor assembly 7 driven by a control shaft 81, and that the switch has a movable contactor 9 adapted to be moved across the inner face of a base 10 of insulating material .to and from bridging engagement with a pair of stationary contacts 11. The contacts 11 are mounted on the base 10 which also serves as the rear wall of a housing in which the switch instrumentalities are contained. The housing is completed by a stamped substantially cylindrical shell 12, suitably secured to the base and attached to the back of the variable resistor'.

The contactor 9 is connected to a carrier arm 15 of insulating material, pivoted, as at 16, to swing across the base 10 and thereby carry the contactor to and from bridging engagement with the stationary contacts. A switch actuating cam 17 overlying the arm 15, is also pivoted at 16, and a spring 18 connected between the Cam and the carrier arm 15 yieldingly holds the latter and the contactor 9 in either switch open or switch closed position.

Although not a part of the present invention, it is to be lnoted that the shell 12, though generally cylindrical, is bulged outwardly, as at 19, adjacent to the pivotal mounting of the cam and contactor carrier; and that the cam is reversed from the position it usually occupies in switches of this type, so that its bifurcated arm 20 faces inwardly rather than outwardly. The purpose of this reversal and non-circular shape of the shell, is to achieve the utmost compactness.

Actuation of the switch from one position to the other is, of course, accomplished by swinging the actuator on its pivot, and, to effect this result, as a consequence of adjustment of the variable resistor, the bifurcated arm 20 of the switch cam projects into the interior of the resistor housing through a hole in its rear wall, to be transiently engaged by an arm 21 which forms an integral part ofthe rotor of the resistor. i

In that embodiment of the invention illustrated in Figures l, 2 and 3, the contactor 9 is of the type illustrated in Patent No. 2,698,369, and, as a. result, it is a generally heart-shaped stamping, so connected to the contactor carrier that the free end portions of its two arms 9 travel forwardly of the point of connection between the contactor and the carrier arm in moving towards bridging engagement with the stationary contacts 11. In Figures 5 and 6, the contactor is somewhat different, not only in its shape and formation, but also in the manner in which it is brought into engagement with the stationary contacts. From the standpoint of Vshape andfformation, the lcontactor of Figures 5 and 6 is essentially V-shaped with divergent flat blades connected together at the apex of the V by a U-shaped p0rtion 26 from which lugs 27 extend edgewi'se to connect the contactor to the contactor carrier arm 15. Hence, during closure of the switch, the -contact engaging portions of the contactor trail the connection of the contactor to its carrier.

In both cases, however, the stationary contacts 11 present cylindrical surfaces to the approaching contactor arms, across which the contactor arms readily slide as the switch is closed and opened, to thus achieve a wiping action which assures the maintenance of clean low resistance connections between the contactor and the contacts.

Since the contact engaging surfaces of the contactor, in either case, are maintained perpendicular to the switch base, it is essential that the surfaces of the stationary contacts engagable thereby likewise be rigidly maintained perpendicular to the switch base. This requirement is fully met by the combined switch contact and terminal of this invention. In addition, the combined Contact and terminal of this invention has the advantage of small size, rigidity and strength, as well as low manufacturing cost and ease of assembly to the switch base.

All this flows from the fact that the combined contactor and terminal is a T-shaped stamping having a head 30 and a stem 31, with the entire stamping uniformly arcuate in transverse cross section, as clearly shown in Figure 4. The stamping thus has an outer convex sur'- face, all portions of which are equidistant from an imaginary line or axis parallel to the longitudinal axis of the stem of the T.

The head of the T which provides the contact, has suflicient width in the flat developed aspect of the stamping shown in Figure 7, to assure that in its final form, it defines substantially a semicircle. Symmetry is thus obtained, and as a result, it makes no difference at which side of the path of the contactor the contact is located. In each instance, identically the same shaped contact surface is presented to the approaching contactor arm.

The stern of the T, of course, denes a lesser arc than the semicircle formed by the head, and that part 32 of the stern which lies directly under the head and may be considered a shank, is taperingly reduced in width toward the outer end of the stem, so that, upon insertion of the stamping into an arcuate slit in the base, this shank portion 32 has a drive tit in the slit 33, as more particularly illustrated in Figure 7. It is, of course, to be understood that the slit must have an arcuate length slightly less than the greatest arcuate length of the shank portion 32 or, when viewed in the at, as in Figure 7, the slit 33 must have a maximum width less than the maximum width of the shank portion 32.

Outwardly of its shank portion 32, the stem of the T is again abruptly reduced in width, to form shoulders 34 which areeasily swedged over the adjacent face of the base, as indicated in broken lines at 35 in Figure 7. In this manner, the combined contact and terminal is anchored to the base 10, with the underside of the head of the T bearing solidly against the base and the contact surface provided by the head, rising perpendicularly from the base.

The outer terminal forming part of the stamping, or, in other words, the stem of the T, may be notched at its outer end, as at 36, to facilitate the attachment of conductor wires thereto.

From the foregoing description, taken in connection with the accompanying drawings, it will be readily apparent that this invention provides a combined contact and terminal which is very well adapted for use in the small miniaturized switches employed in television and radio receivers, and usually mounted on the back of a volume control, or other variable resistor, since, through it, small size is combined with increased strength and stability. p

What I claim as my invention is:

A combined stationary contact and terminal for use in an electric switch mechanism wherein a movable bridging contactor is actuated back and forth across one face of a substantially fiat base of insulting material, toward and from wiping engagement with surfaces of stationary contacts that are perpendicular to the base, said combined stationary contact and terminal comprising: a generally T-shaped metal stamping having a head, a stem, and a wedge-like shank connecting the stern and head, said shank having a width greater than that of the stem but less than that of the head so that the end portions of the head which project beyond the opposite marginal edges of the shank provide abutments having surfaces which face toward the outer end of the stem and lie in a common plane normal to the longitudinal axis of the stern, a portion of the wedge-like shank which is adjacent to the head being taperingly reduced in width to provide marginal edges on the shank which are slightly inclined to the longitudinal axis of the stern and are adapted to have a drive t in an opening through a switch base when the stem of the stamping is projected through said opening, and the portion of the shank which is adjacent to the stem being abruptly reduced in width toward the stem to provide steeply inclined shoulders on its opposite marginal edges generally facing away from the head of the T, portions of said shoulders being adapted to be swedged outwardly beyond the slightly inclined edges of the shank to provide abutments spaced from and opposing the abutments on the ends of the head and cooperable therewith to clamp portions of the switch base therebetween and thus provide for securement of the cornbined stationary contact and terminal to the base; and said T-shaped stamping being uniformly arcuate in transverse cross section so that the stern and shank are stiffened against bending, and so that the T has an outer convex surface all portions of which are equispaced from an imaginary line parallel to the stem of the T, the radius of curvature being shorter than the width of said shank portion having the slightly inclined marginal edges, and being such that the head of the T forms substantially a semicircle, the outer convex side of which constitutes the active contact surface of the stationary contact and is disposed in perpendicular relation to the adjacent face of a flat switch base to which the combined stationary contact and terminal may be fixed.

References Cited in the file of this patent UNITED STATES PATENTS 2,805,291 Eickhorst et al Sept. 3, 1957

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