US2820125A - Contact means - Google Patents

Description

c. HUETTEN CONTACT mus Original Filed Nov. 28. 1950 Jan. 14, 1958 I I 2,820,125

INVENTOR filafhce Hueizen/ Unite CONTACT MEANS Clarence Huetten, Mallory & (30., of Delaware 1 Claim. (Cl. 200-166) Indianapolis, Ind, assignor to P. R. Inc., Indianapolis, Ind., a corporation The present invention relates to electrical circuit controllers such as vibrators, ignition contact breakers, and various other types of contactors, and has specific pertiriency to such apparatus and methods directed to provide improved contact structures for devices of this character.

The contact structure of the present invention relates particularly to circuits utilizing circuit breakers employing a contact arm which is adapted through the use of a rotary cam to carry the contacts, per se, into and out of engagement with a cooperating stationary contact. The contacts used in these ignition circuits and for vibrators, etc., heretofore employed, presented problems usually resulting from difi'iculties of high interface resistance, contact transfer and slow speed of contact separation. By the present invention there is provided a contact structure which is adapted to overcome the above difficulties. This application is a divisional application of copending U. S. application Serial No. 197,965, filed in the United States Patent Oflice on November 28, 1950.

The present invention, therefore, provides a novel form of contact structure constructed so as to offer a substantially compliant or flexible mating surface of substantially thin cross-section. As a result thereof, the problem of transfer is substantially lessened. The structure, as hereinafter described, limits transfer, contact bounce, and permits a faster break velocity for the contacting element.

It is, therefore, an object of the present invention to provide a novel contact structure which is readily fabricated, easily assembled, inexpensive and effective in preventing inefiiciency resulting from contactors showing early contact failures as a result of transfer of contact material.

Still another object of the present invention is to provide an improved contact for ignition circuits wherein the efiiciency of said circuits is increased because of the lessened high interface resistance and contact transfer from the novel structure of the contact invention.

Still another object of the present invention is to pro.- vide a contact for use with contact breakers wherein the contact element is provided with a substantially compliant surface so that an improved type of make and break relation is obtained between said contact and an associated fixed contact.

Still another object of the present invention is to provide a contact structure characterized by improved characteristics of interface resistance, contact transfer and speed of separation.

The invention, in another of its aspects, relates to novel features of the instrumentalities described herein for teaching the principal object of the invention and to the novel principles employed in the instrumentalities whether or not these features and principles may be used in the said object and/or in the said field.

Referring to the drawings:

Figure l is a plan view of the improved contact including as a portion thereof a compliant face or surface of the present invention, and as adapted to be used with States atent 2 an electrical circuit breaker, the embodiment being shown having a cylindrical shape with its base being welded to the contact arm at the periphery thereof; 7

Figure 2 is a longitudinal, cross-sectional view of the embodiment of the present invention of the improved contact make and break device shown in Figure 1, taken along line 22 thereof and as adapted to illustrate the novel structure of the contact element therein;

Figures 3 and 4 are illustrations of the structural configuration of the contact used in Figures 1 and 2 as adapted to illustrate the substantially hollow structure of the contact;

Figure 5 is a profile view of an alternative embodiment of the contact structure of the invention showing the configuration of the said structure as being of a pyramidal construction having separated triangular mating sections; and

Figure 6 is a cross-sectional view of the contact structure shown in Figure 5 as taken along line 6-6 thereof.

Referring to the drawings, the present invention pro vides means for affording a contact structure which may be used in ignition circuits, vibrators, etc., to improve the characteristics which relate to interface resistance between the moving contact and its associated fixed contact element. The novel contact minimizes losses due to interface resistance, contact transfer and slow speeds of separation. By the structure of the contact here described, a contact is provided which allows for the limiting of contact transfer or migration of the contact material during the operation of its incorporating device.

The contact consists of a thin sheet of contact material such as tungsten or molybdenum punched and formed as illustrated. The contact may be fastened at its peripheral area such as by welding or clamping while the central structure is the actual contacting surface.

Heretofore, although in many devices only a small portion of the contact material was needed, greater thicknesses were used for convenience in fabrication and assembly so as to prevent early failures resulting from high resistance. Thus, in the event transfer or erosion occurred over a relatively small area, the contact might mate with the base metal if the contact material were too thin and as a result of which high resistance resulted. In the present novel contact the transfer from it to an associated mating contact is limited by the thickness of the contact itself. At the same time there is a small space between the contacting surface and the base so that as the compliant member deflects it will maintain contact with the mating surface even though the transfer spike may go through to the base material.

In the case where transfer is such as to deposit material on the contact, the build up of the transfer is limited by the flexing of the contact surface. Further, the flexing contact surface may stress the transferred material so that it may fall off as erosion dust. In addition a slight radial sliding action will occur tending to shear olf larger transfer spikes and keep the mating surfaces relatively free of oxides, etc

Contact transfer and erosion and contact heating vary of the order of the current squared. Thus, as described and shown in Figures 5 and 6, the separated members assure a larger number of contacting spots and since there will be some current division between the spots the maximum current through a particular spot is, in general, less, and hence the effects of contact transfer, erosion, and heating are reduced.

Referring to Figures 1-4, the contact of the invention is constructed of a thin sheet of contact material formed into a cylindrical cupola or hat-like shape which may be welded to a support at its periphery, the contacting area thus being unsupported by any base metal. The contact 10 comprises a top face or disc 11 adapted to make contact with an associated fixed contact 12 supported on a bracket 13 of the circuit breaker. The contact element 10 has its face 11 raised a substantial distance from the contact arm" 1 4 to which it is connected by. means of a Canaries-11y shapedsic'l'e wall structure 153 The entire contact, including the face portion and the side wall portion, iswelded to the contact arm 14 at its'periphery 17. As illustrated inFigure 4'; the contacting area or face 11 is unsupportedbyany'ba'se metal and presents asubstantiallyhollowstructure. As an aid in preventing oscillations; at" dampening structure 30-" maybe included with contact 10.

As aresulfofthe above construction, contact transfer or migrationis limited to'the thickness of the contact material. This not only limits the height of such tr'a-ns'f'er 'but force'sa better utilization of the contactmateria'l It hasb'eenfound, when'attempts are made to limit transfer by supportinga thin contact on a base metal, transfer occurs until-thetransfer pip hits the base metal and high resistance results. The present contact structure; however, overcomes this difliculty. The contact structure described is readily "fabricated, easily assembled and' is in'expensive; The novel structure of the present invention has been found etfective in preventing early contactfail'ures asa result of contact transfer or migration.

ln Figures 5 and 6-the' contact having a yielding surface is shown as comprising apyrainidal construction 20, having separated triangularsections or -faces 21, 22, 23, 245 Each of'the section's hasb'een substantially raised above the contact arm itself so asto approach a confluxing point or apex 25. The separatetriangular faces such as 21 and 22 are adapted to be connected-to the contact arm peripherally as at 27 by means of welding the said sections to the arm. Thus the structure of the contact has a greater compliance than usual and which affords means for overcoming contact transfer or migration since, as pointed out above, contact" transfer or migration has been substantially lessened because of the reduced thickness of the contacting area.

The presentinvention of acontact with a compliant surface, as described above, ismerely illustrative and not exhaustive in scope and since many widely different embodiments of the invention'may be made without de of said contactmembers comprising a single cup-shaped structure free of internal solid material having a top-ann'ular' flexing disc, side walls vertically depending therefrom s'o asto'form a cup-like structure thereby, andmeans for connecting said dependent side wall structure to associated supporting structure.

R'cfrencesi'iited in the file of this patent UNITED STATES PATENTS Johnson Mar; 24; 1942

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