US1184706A - Resistance-grid. - Google Patents

Description

W. H. KELLER.

RESISTANCE GRID. APPLICATION FILED JAN. 6. 1914.

1,184,706. Patented May 23, 1916.

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Specification of Letters Patent.

Patented May 23, 1916.

Application filed January 6, 191& Serial No. 810,545.

To all whom it may concern Be it known that I, WILLIAM H. KELLER,

a citizen of the United States, and resident of Norton, in the county of Wise and State of Virginia, have invented certain new and useful Improvements in Resistance-Grids, of which the following is 'a specification.

This invention relates to those electrical resistance units which are of a -stifi' plate like character and have separated parts somewhat resembling a. grid iron,jso that they are known in the art as grids.

In using the resistance grids usually a plurality of them arev supported in a suitable frame or on a suitable support, being suitably insulated from each other and c0nnected together in desired relations, either in series or in parallel, ora combination of the two systems. and connecting grids is'well; understood in the art. The grids are usually clamped in position between end plates or screwed tightly. to a support by means of screws passing into the feet of the grids, the conduc tivity of the electrical connection between the grids or from a'grid to a connecting piece being dependent upon the secure clamping of the parts together. Where cast iron or other brittle grids are tightly clamped they are liable to break. They are also liable to breakage by being accidentally struck or by jarring or jolting, such as that to which grids'are sub ected upon electric locomotives or other vehicles.' Also, grids heretofore in use are liable to warp when hot, so that adjacent grids of a rheostat may come together and short circuit a portion of the resistance unless the grids are placed so far apart that this contact cannot occur. 40 It will be apparent, however, that this will prevent compact construction of the rheostat and a compact construction is certainly greatly to be desired, if not absolutely necessary, on locomotives and Y space is valuable.

It is an object of the present invention to provide a resistance grid which shall be inexpensive to' manufacture, which shall answer the purpose of a resistance unit efliciently, which shall not be liable to be broken by jarring or jolting, which may. be clamped tightly to secure good electrical connection and secure support and which will not be warped by the heating due to the passage of the electric current.

The objectof the invention is accom- The manner of mounting employed,

other places where I plished by providing a grid of iron of suflicient ductility so that the grid may be stamped or cut by a die from of suitable thickness. Iron of the character referred to is found in that class of the metal known steel. ductilit etc., may be summed up in the word malleable. My experience in the matter has shown that steel is highly preferable and possesses numerous advantages.

Grids of the character described may be tightened into good electrical contact, are not broken by warp when hot and may be inexpensively produced by punching by simple dies from plane sheets of metal. The metalis not expensive, which permitsthe use of lar as wrought iron and also in gegrids for carrying large quantities without alarge expenditure and at the same time an eflicient resistance unit is supplied. Also, this permits as a commercial proposition the use of a grid of suiiicient size so that, taking into consideration the character of the metal conformation of id to accomplish this end.

e invention is illustrated in the accompanying drawing, of which- Figure 1' is a side elevation of a rheostat including grids according to the present invention; Fig. 2 is an end view of the rheostat shown in Fig. 1; and Fig. 3 is an en larged view of a grid according to the present invention, the manner of its mounting and insulation in the rheostat of Fig. 1 being indicated.

eferring to the drawing, which the grids are to be mounted comprises the end plates 0 and b between which extend the bolts 0, d and 0, having nuts outside the ends of the plates as shown. Between the plates are arranged grids f.

The structure of a grid is shown best in Fig. 3, from which it appears that each grid comprises the reflexed portions 1, 2, 3, 4, 5 and 6, thus providing a long path for the current in going from one side of the grid to the other; At one end of each of the outside grids is a hole through which the bolts (1 and e pass, while at the middle of the grid upon the opposite side from the tioned is another hole through which is threaded the bolt 0. The grid is ordinarily arring or knocking, will not it is self sustaining to a great extent and does not require any peculiar holes. men

a sheet of iron The desired qualities of pliability,

the frame in or bushings '7, 8 and 9, which envelop the bolts and adjustment grids may be insulated from each other where desired by means of insulating washers as 10 and 11, which are interposed between the grids and threaded upon the bolts. Preferably the insulating bushings and washers referred to are made of mica, although other insulating material might be employed.

Each grid is punched from a sheet of steel of suitable thickness and all of the parts of the punched grid lie in a lane sheet. As noted above, other forms 0 iron than steel may be employed but do not realize all the advantages to the same extent as the steel.

It will now be apparent that in order to farm the rheostat as shown in Figs. 1 and 2, t e bushings on the bolts d, c and'e, the plates a and b are placed on the ends and the nuts on the bolts are tightened so that the whole is clamped firmly together, insulating washers having been placed between the grids upon the bolts where it is desired to separate the grids while such washers are omitted or metallic desired to establish electrical tween adjacent grids.

The end plates (1. and b of the rheostat are provided with feet as 12 and 13, through which screws or bolts may pass into the support, such as the floor of a car, in order to secure the rheostat in position.

Electrical connection may be made to the grids in any of the ways well known in connection bethe art.

While the invention has been illustrated in what is considered its best application, it may be embodied in various structures without departing from its spirit and is not rids are'threaded over the insulatingwashers inserted where it is therefore limited to the structure shown in the drawing.

What I claim is:

1. In a 'rheostat, the combination with supporting rods, of a plurality of reflexed resistance grids mounted thereon, means for clamping said grids toward each other endwise of said rods, means for spacing said grids along said rods so that air spaces are formed between them, and means for insulating said grids from said rods and each other at desired points, each of said grids being punched from sheet steel and having the greater portion of its surface exposed to the air.

2. In'a rheostat, the combination with a support, of a plurality of reflexed resistance grids of sheet steel mounted thereon, said grids being spaced apart so that air Spaces are formed between them, insulated from each other at desired points and each having the greater portion 0. its surface exposed to the air.

3. In a rheostat, the combination with a sup ort, of a plurality of reflexed resistance grl s of malleable metal consisting in the.

greater art of iron, mounted thereon, said grids being spaced apart so that air spaces are formed between them and insulated from each other at desired points, and each having'the greater portion of its surface exposed to the air.

Si ed at Norton, in the county of Wise, and tate of Virginia, this 31st day of December, A. D. 1913.

WILLIAM HENRY KELLER.

Witnesses:

R. B. COWAN, Geo. I]. Ro'rEBUcK.

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