US3657505A - Electrical contacting arrangement - Google Patents

Abstract

A composite electrical contact structure which includes a laminate of an aluminum layer bonded to a layer of high-grade contact material such as copper or silver onto the aluminum layer of which is then cast a base body of aluminum or aluminum alloy. During casting of the base body, the surface of the aluminum layer is fused by and becomes united with the molten aluminum upon solidification of the latter.

Description

United States Patent Mosele [4 1 Apr. 1%, H972 [54] ELECTRICAL CONTACTING References Cit ARRANGEMENT UNITED STATES PATENTS Inventor: Joset Mosele, Obere Brucke, Othmarsin- 3,198,662 8/1965 Seibert ..200/166 0 ux gen, Switzerland 3,299,240 1/1967 Foti ..200/l66 C Mar et al C [21] Appl. No.: 18,085 Primary Examiner-41. 0. Jones Attorney-Pierce, Scheffler & Parker [30] Foreign Application Priority Data 57 ABSTRACT P 1,1969 Switzerland -4943/69 A composite electrical contact structure which includes a laminate of an aluminum layer bonded to a layer of high-grade [52] US. Cl. ..200/166 C, 29/630 C contact material such as copper or silver onto the aluminum [51] Int. Cl. ..H01h 1/02 layer of which is then cast a base body of aluminum or alu- [58] Field of Search ..200/166 C; 29/630 C m n alloy. ng ng o the e o y, the surface of the aluminum layer is fused by and becomes united with the molten aluminum upon solidification of the latter.

2 Claims, 1 Drawing Figure PATENT EDAPR 18 1972 3, 657', 505

Fig.2

INVENTOR. Jose I MoseLe BY At me s 1 ELECTRICAL CONTACTING ARRANGEMENT The present invention relates to an electrical contact arrangement, especially for power circuit breaker apparatus, in which a base body of aluminum or aluminum alloy is joined to a contact piece of high-grade contact material by casting.

In bodies of aluminum or aluminum alloy which serve for the conduction of current and the transmission of current to other parts, the point where contact is made has received particular attention for a long time. A satisfactory solution, however, has not yet been found to date. Thus, contact pieces of high-grade contact material, for instance, copper or silver, have been applied to an aluminum base body in various ways. Besides bolting on of copper parts, it is known among other things how to fasten sheet silver to the aluminum base body by means of spot welding for the purpose of providing contact. It is true that with this letter method a usable contact point is obtained at the silver-aluminum transition, but the contact areas outside the welding points are poorly utilized with regard to current and heat transfer. It is also known to join current transfer contacts of high-grade contact material, for instance, copper, to the aluminum body by casting, wherein the aluminum is cast onto the copper parts as a die casting, or the latter are cast into the former. Here, however, a more or less imperfect transition resistance cannot be avoided, as no intimate, continuous bond between the aluminum body and the contact material comes about. The present invention is based on the task to find a solution for applying contacts to a base body of aluminum or aluminum alloy with a high-grade material, in which the contact transition is substantially improved over the arrangements so far proposed, with respect to from the electrical as well as thermal aspects. in accordance with the invention it is proposed that the contact piece-be a composite body consisting of aluminum and the high-grade contact material, the aluminum side of which faces the base body. In this manner there is obtained between the base body and the aluminum side of the composite body an intimate, homogeneous metallic bond which remains free of corrosion and in which the entire cross section of the transfer area is utilized.

The accompanying drawings show two examples of implementation of the invention.

FIG. 1 is a half longitudinal section showing the point of contact between two tubular conductors, and

FIG. 2 is a similar sectional view showing a sliding contact arrangement.

In FIG. 1 the two tubular conductors l and 2 are arranged so that they butt against each other with their end faces. The conductors 1, 2 consist of aluminum or aluminum alloy and each have at the end face the contact bodies 3 and 4, respectively, each of which, as.a composite body, consists of two layers 3a, 3b and 4a, 411, respectively. The layers 3a and 4a, respectively, consist of aluminum and the layers 3b, 4b respectively consist of high-grade contact material, such as for-example, copper or silver. Such composite bodies are manufactured by rolling together under pressure and heat to form a laminate and are commercially available in various forms, for instance, in plate form, for instance, as the so-called Cupal plate. Thicknesses from 0.5 to 8 mm with different layer thickness ratios of Al to Cu or Ag, respectively, are common. The tubular conductor part 1 can for example, be cast from an ingot of aluminum alloy, wherein the laminated body 3 is placed into the casting mold prior to pouring the molten aluminum into the mold, in such a manner that the aluminum side, layer 3a, faces the casting zone for the conductor body 1 as the latter is cast. It is of advantage to use technically pure aluminum (99.5 percent) for the composite body since this avoids destruction of the bond between the layers 3a, 3b of the composite body 3 during the casting and fusion of the aluminum layer 30 as the latter is joined to the adjacent surface of the aluminum conductor body during its solidification following pouring, and possibly, the refining process, since in this case the processing temperature is sufficiently below the melting temperature of the eutectic of the transition alloy Cu or Ag, respectively, against the pure aluminum inthe composite body.

At the inside and outside diameters, the composite bodies 3, 4 and an adjacent portion of the conductor 1, 2 can be covered with a suitable protective lacquer, so that access of air and moisture to the contact point is prevented. The required contact pressure between the conductors l and 2 can be achieved, for example, by pressing them together in a manner known per se, not shown in detail. If the contacting layers 3b, 4b consists, for example, of copper, they can be silver-plated after they have been faced off to make them flat.

In FIG. 2 the ring shaped composite body 8, built up from the aluminum and copper layers 8a, 8b, is cast into the outer surface of the tubular shaped aluminum base body 5. On the side of the outer layer of high-grade contact material 8b rest the contact fingers 9. There are several of these fingers 9, distributed around the circumference. They can consist, for example, of silver-plated copper and are held in a fixed cage 10, with the insertion of the contact pressure springs 11. Within the part 5 is accommodated, by means of an insulating plastic ring 7, a nozzle switch piece 6 which is supported and driven so that it can reciprocate in the direction of the double-headed arrow 12. The switch piece 6 consists, for example, of silverplated copper and the right-hand ends of the fingers 6 slide on it. The two end faces of the sheet-shaped composite body 8 each can terminate in a small recess in the shape of an annular groove in the base body 5, so that they do not touch the latter. The groove can be filled with a protective lacquer which possibly also covers the bodies 5, 8 to some extent.

I claim:

1. A composite contact structure comprising a laminate consisting of an aluminum layer bonded to a layer of highgrade contact material and a base body essentially of aluminum cast upon and fused with said aluminum layer.

2. An electrical contact structure as defined in claim 1 wherein said aluminum layer consists of technically pure (99.5 percent) aluminum.

mm m. 3, 57,505 Dated April 1 1972 Inventor (X) MOSELE JOSEF I: is ccrtificd that error appears in the and ch-1'7; uaid Letters Patent a.

rc hereby corrected as shown below:

' In the-fheaqlng of the ,patent the identity of the a sl n eg ."to wit: .AKTIENGESELLSCHAFT v BROWN, 'BOVERI & 'cIE.', BA'DEN, SWITZERLAND, should appear.

-S ignedand se aled, this 10th day of October 197;.

(SEAL) Attest: v EDWARD MQFLE'TCHIERQJ'RD W ROBERT GOTTSCHALK Attesting' Officer- Commissioner of Patents

Claims (1)

1. 2. An electrical contact structure as defined in claim 1 wherein said aluminum layer consists of technically pure (99.5 percent) aluminum.

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