US481781A

US481781A - Third to w

Info

Publication number: US481781A
Authority: US
Publication date: 1892-08-30
Anticipated expiration: 1909-08-30

Description

( odem 0. E. CARPENTER.

' RHEOSTAT.

No. 481,781. Patented Aug. 30, 1892.

UNITED STATES PATENT OFFICE.

CHARLES E. CARPENTER, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR OF ONE- THIRD TO I. S. ANDREWVS, OF NEIV YORK, N. Y.

RH EOSTAT.

SPECIFICATION forming part of Letters Patent No. 481,781, dated August 30, 1892.

Application filed February 18, 1891. Serial No. 381,825. (No model.)

To all whom it may concern:

Be it known that 1, CHARLES E. CARPENTER, a citizen of the United States, and resident of the city of Minneapolis, county of Hennepin, and State of Minnesota, have invented certain new and useful Improvements in Rheostats, of which the following is a specification.

This invention relates to improvements in rheostats or resistances; and has for its prime object to simplify the construction and reduce the cost of manufacture thereof, while at the same time rendering the device more durable and compact in form. This object is accomplished by the devices illustrated in the accompanying drawings, in which-- Figures 1 and 2 represent top plan views of rheostats embodying my invention with parts broken away, so as to more clearly show the internal construction thereof; Fig. 3, atransverse vertical section of Fig. 1, and Fig. 4 a detail section taken on the line 3 3 of Fig. 1.

Similar letters of reference indicate the same parts in the several figures of the draw lugs.

Referring by letter to the accompanying drawings, A indicates a base-plate of some suitable metal for receiving a coating B of enamel or similar vitreous material which is adhesive and is a non-conductor of electricity. Many such materials, suitable for the purpose of my invention, are now manufactured and applied to many kinds of utensils, generally in a plastic condition and fused for the purpose of attaching to the article, and sometimes are applied in a liquid or powdered state; but the process of manufacture of such material and the methods of applying the same form no part of this invention. In this coating is embedded a conductor or resistance C, preferably consisting of fine wire of the reflexed type, covering practically the entire surface of the base-plate, the sections of which are by the coating of enamel or equivalent material secured firmly in position upon but insulated from the base-plate and correspond with the usual coils of a rheostat.

111 some kinds of work-such as electricallyoperated street-cars and in some electric-light systems-the rheostat employed may have a fixed and unchanging resistance which is predetermined, and therefore no means need be provided for altering or varying the resist ance of the same. IVhen such is the case, the instrument may be constructed, as shown in Fig. 2, with any desired number of sections of the resistance or conductor, terminating at the ends, respectively, at the binding-post C for convenience in introducing the rheostat into the line-circuit, the number of' sections and the size and character of the conductor determining the resistance offered by the apparatus. In other cases, however, it is desirable to have the rheostat so constructed as to be adjustable for varying resistances, as usual in this class of devices, and when such an instrument is required it will have the general character illustrated in Fig. 1, which I will now proceed to describe. In the coating of enamel is also embedded the connectorwire D, leading from the pivot E of the switch-key F to the binding-posts G, as shown by dotted lines in Fig. 1, and also a series of contact blocks or plates 11, arranged on the arc of a circle from the pivot of asWitch-key, and with which such key makes successive contact in cutting out or in the resistance, each section being connected by the short wires I with a contact block or plate.

In the practical manufacture of these devices I have found it most advantageous to first coat the base-plate uniformly over its entire surface, then set the various resistance coils or sections, wires, and contact-blocks when used in position, and afterward applying one or more coatings of the enamel or equivalent material, covering the wires, but leaving the upper faces of the contact blocks or plate exposed, the blocks for the greater security against displacement being provided with a lateral flange J around their base, which is covered by the enamel.

To prevent any undue heating of the base plate when heavy currents are passed through the resistance, the back thereof may be ribbed, corrugated, or provided with a series of projections, as shown at K in Fig. 2, which permits a free circulation of air around the back of the plate, and at the same time exposes a large surface for the radiation of the heat.

By my invention the cost of construction of rheostats or resistances is reduced to the minimum, while the simplicity, compactness,

and durability thereof is promoted to the maximum degree, the enamel or equivalent material serving to retain the resistance coils or sections in position against displacement, protects them from external injury, avoids the danger of fusion of the resistance, and perfectly insulates the coils or sections from their support and from each other.

Having described my invention, What I claim, and desire to secure by Letters Patent, 1s-

1. A rheostat or resistance comprising a base-plate corrugated, ribbed, or recessed on the rear face thereof and provided with a coating of enamel or similar vitreous material on the front face and resistance coils or sections embodied in such coating, substantially as and for the purpose described.

2. Arheosl'at. nnmnrisino" a. base-late. nrnvitreous material, a series of resistance coils or sections, and a corresponding series of contact-blocks therefor embedded in such coating, and a switch-key co-operating with such series of blocks, substantially as described.

3. A rheostat comprising, a base-plate provided with a coating of enamel or similar vitreous material, a series of resistance coils or sections, and connecting-wires embedded in said coating beneath the surface thereof, but out of contact with the base-plate, a corresponding series of contact-blocks also embedded in said coating", but projecting beyond the surface of the same, and a switch-key cooperating with series of blocks, substantially 3 5 as and for the purpose described.

CHARLES E. CARPENTER. Witnesses:

A. (3. 711mm;