US1063303A - Electrical resistance. - Google Patents

Description

UNITED STATES PATENT orrion.

ELIHU THOMSON, or SWAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO GENER ELECTRIC COMPANY, A CORPORATION on NEW YORK.

ELECTRICAL RESISTANCE.

Specification of Letters Patent.

Patented June 3, 1913..

' To all whom it may concern:

Be it known that I, ELIHU THOMSON, a citizen of the United States, residing at Swampscott, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Electrical Resistances, of which the following is a specification.

This invention relates to electrical resistances and has for its object the provision of a unit which will have a high resistance, is simple and inexpensive to construct and at the same time, very etiicient and durable.

My invention relates more specifically to resistance materials which have a high resistance and low heat conductivity. Such materials, for instance, as boron, have a high resistance and also a high negative temperature resistance co-efficient and low heat conductivity. Because of this combination of physical properties, such a material will allow but a very small leakage current to pass until the impressed voltage exceeds a certain break-down value and when this voltage is exceeded the resistance very suddenly falls to a lowv value. In the meet this material, especially in large sections, it is found that the current will concentrate in a particular part of the section, instead of flowing uniformly over it.

-The object of my invention, therefore, is to overcome this objection by arranging a heat conducting material 50 that it will conduct the heat uniformly throughout the sections.

In carrying out my invention I employ layers of resistance material and place between the layers a good heat conducting material. The layers are arranged alternately so as to form a complete unit and pressed together in some manner, as for instance, by a springpressure.

In the accompanying drawings in which I have shown my invention embodied in concrete form for purposes of illustration, Figure 1 represents a complete unit, partly broken away; Fig. 2 shows two of the elements composing the unit in perspective;

F ig. 3 shows a modified form of element; and Fig. t shows still another form.

Referring to the drawings, 10 represents a layer or plate of resistance material such as boron or the like. This material has a h co-efiicient and low heat conductivity, A

resistance, but a negative temperature plurality of these disks 10 are arranged alternately, as shown in Fig. 1, with a plurality of similarly shaped plates of metal having a high heat conductivity. I have found that where boron is used as the resistance element copper plates 11 serve the purpose of heat radiators or conductors, as its heat conductivity is high and it does not combine with the boron. These alternate plates or disks 10 and 11 are mounted between brackets 12 and 13 and pressed together by means of a spring 14. One terminal connection is made at having a plate 16 which is pressed against the uppermost copper plate and the other terminal connection is made at 17 with the lowermost copper plate, as shown. In this manner the heat which is developed in the resistance plates 10 is distributed throughout the plate and a more uniform resistance,

combined with a uniform heat, is obtained.

Instead of applying the alternate disks as shown in Figs. 1 and 52, substantially the same result may be obtained by coating one side of the metallic plate with boron, as shown in Fig. 3. In Fig. 4:, I have shown another method of accomplishing this result, wherebythe heat is dissipated rapidly. In this case the resistance plate 18 is clamped between two conducting plates 19 and separated from thenext element by an air gap so as to surface. 'The underlying principle is the same, however, as in the form shown in Figs. 1 and 2, namely, the furnishing of heat'conducting means for causing the re' sistance material to be of uniform temperature.

- While I .have described my invention as embodied in concrete form and employing specific materials for purposes of illustration, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

furnish a large radiating What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In a reslstance unit, the combination of a material having a high "cold resistance and a high negative temperature resistance coeflicient similar to boron, and a body of material having better heat conductivity than 'loorori in thermal and electric conductive relation thereto.

2. The combination of adliskof looron material, and a metallic elisk of good heat 5 conductivity in contact therewith. 3. The combination of a plurality of 1 plates of material of the nature of boron in its electrical break-down characteristics and a plurality of heat radiators in thermal-and electrical contact with said, plates. 10 I in Witness whereof, I have hereunto set my hand this first day of July, 1909.

ELIHU THUMSUN. Witnesses:

JOHN A. MoMANUs, Jr., QHARLES A. BARNARD.

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