US755468A - Rheostat. - Google Patents

Description

PATENTBD MAR. 22, 1904.

'A. G. EASTWOOD RHEOSTAT.

APPLIOATION FILED DBO. 21, 1903.

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PATENTED MAR. 22, 1904. VA. 0. EASTWOOD.

RHEOSTAT. APPLICATION FILED 11mm, 1903.

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No. 755,468.' PATENTED MAR. 22, 1904.

- A. c. EASTWOOD.

RHEOSTAT.

APPLIOATION FILED DEG. 21, 1903.

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PATENT OEEICE.

ARTHUR O. EASTWOOD, CLEVELAND, OHIO.

RHEOSTAT.

SPECIFICATION forming part of Letters Patent No. 755,468, dated March 22, 1904.

Application filed December 21, 1903. Serial No. 186,141. (No model.)

To all whmn it may concern:

Be it known that I, ARTHUR O. EASTWOOD, a citizen of the United States, residing in Cleveland, Ohio, have invented certain Improvements in Rheostats, of which the following is a specification.

My invention relates to certain improvements in that class of apparatus especially designed for the absorption and dissipation of electrical energy, and has for its object the production of a rheostat composed of a number of sections so arranged that all wiring connectionsbetween them and the corresponding contacts on the controller shall be eliminated. It is further desired that the rheostat shall be of a simple and durable construction and shall consist of a relatively small number of parts of such a nature that they can be manufactured and assembled with a minimum,

of labor and expense. These objects I attain as hereinafter set forth, reference being had to the accompanying drawings, in which Figure 1 is a plan view of one ofthe sections forming part of my improved rheostat. Fig. 2 is an end elevation of the rheostat-section shown in Fig. 1. Fig. 3 is a sectional elevation on the line 3 3, Fig. 1. Fig. 4 is a side elevation of my improved rheostat with its parts in their assembled positions. Fig. 5 is a side elevation of a portion of my improved rheostat. Fig. 6 is a sectional plan view on the line 6 6, Fig. 4. Fig. 7is a diagrammatic view showing the electrical connections of the rheostat. Fig. 8 is a plan view of a special form of section for my improved rheostat, and Fig. 9 is an end elevation of the section shown in Fig. 8.

In the above drawings, A is a flat plate or grid of metal having at each end projecting portions provided with bosses a, in which are formed holes for the reception of vertical bars at. These bars are suitably fitted into the frame B of the rheostat, which preferably is of the general construction shown in Fig. 4.

Extending in the plane of the plate A and held thereto by thescrews a is a spring contact-finger a which carries at its end a contact-button o and is in electrical connection with the body of said-plate. A screw a passes through the spring-finger a and bears against the end of the plate A, being provided with a jam-nut, as shown, whereby it may be kept from turning after having been adjusted in said finger.

Upon the body or main portion of the plate A is placed a covering of mica 6, preferably shellacked in place, and upon this is cemented a thin layer of asbestos paper Z2 asolution of silicate of soda being preferably employed as a cement. Over this body of insulating material is wound a suitable resistance material, (indicated at 12 this being in the form of a coil of wire which at one end is electrically connected to the metallic body of the plate A by means of a screw 1) and at the other end is passed through openings in an insulating-washer 5 held in the body of the supporting-grid, so as to be firmly retained in position while being free for connection to an adjoining section.

In assembling the various sections they are placed. one above the other, as shown in Figs. 4: and 5, with insulating-washers 0 between the adjacent bosses a, and the free end of the resistance-wire of each grid is clamped under the screw 6 of each resistance-section next adjacent to it, it being noted that said sections are for this purpose alternately placed end for end'upon the supporting-rods a.

Carried upon a vertical shaft adjacent to the vertical column of resistance-sections is a metallic cylinder D, having riveted or otherwise suitably attached to its outside surface a series of contacts d, so placed as to successively engage with the spring contact-fingers a when the cylinder D is turned by means of its handle d. If desired, the said cylinder may be made of cast-iron and the contact-buttons of brass, these latter being provided with an asbestos washer d held between their head portions and the body of the cylinder, so as to prevent the possible formation of an are between the contact-finger and said cylinder.

The relative arrangement of electrical connections is preferably that shown in Fig. 7 in which the contacted are placed upon the surface of the cylinder in a spiral line, so as to successively come in engagement with the spring contact-fingers a whoseends lie in a straight line and which are connected to the various resistance-sections. In the present instance only the alternate resistance-sections are provided with contact-lingers, although it will be understood that any desired number of resistance-sections may be made to serve as a unit in the rheostat considered as a whole.

One of the contacts d on the cylinder D is in the form of a portion of a ring and is placed in the present case so as to be opposite the lowermost contact-finger, which is in direct connection with one of the current-mains E and E.

As long as the controller-cylinder D is in operation the lowermost contact-finger is in engagement with the long contact-plate (Z and with the connections shown in Fig. '7 all of the resistance comprised by the five re sistance units is in series with the two currentmains E and E, while when the cylinder D is turned sufliciently far to bring the two lowermost contact-fingers a in engagement with the contact (Z and lowermost of the small brass contacts (Z, respectively, it will be seen that the lowermost section of resistance a is short-circuited. Since said contact (Z and the contact-ring (Z are provided with a low-resistance connection through the body of the metallic cylinder D, as the said cylinder is still farther rotated on its axis the various sections of resistance '1", r 1", and 1- are successively cut out, until finally the current from the main E enters the highest of the contactbuttons (Z and passing through the metallic body of the cylinder D finally flows out through the contact-plate (Z and the lowermost of the spring-fingers (0 It will be noted in Fig. 4: thatIhave shown a spring contact-finger mounted on every second grid, so that two units of resistance form a section. It is evident, however, that by mounting a similar set of fingers on the op: posite ends of the grids and providing the necessary contacts one section may be cut out at a time.

When it is desired to employ my improved rheostat in connection with apparatus requiring heavy currents, I employ resistance-sections of the construction shown in Figs. Sand 9, in which the body of the grid A is made to serve as the resistance material. In practice this form of grid is usually of cast-iron and constructed with any number of slots extending into its body from its edges, so that it forms a relatively long and continuous conductor. As in the case of the supportinggrid A, it has bosses at, of which there are in the present instance two on one side and one on the other for the reception of the bars a belonging to the supporting-framework of the rheostat. Similarly, the contact-finger a is in direct electrical connection with the body of the grid, there thus being, as in the other form of my invention, no connections or secondary contacts between the spring-finger and the resistance material.

In the structure shown in Figs. 8 and 9 one of the bosses at has a contact-finger connected to it, while a second boss serves for the attachment of a metallic piece a, through which current flows to one of the resistance-sections next adjoining.

I claim as my invention 1. A resistance-section consisting of a metallic supporting-body, a resistance material wound thereon, and electrically connected to said body, with a piece for making electrical contact also connected to said body, substantially as described.

2. A resistance-section consisting of a metallic plate, a covering of insulating material therefor, resistance material wound on said plate and electrically connected thereto, and a contact also connected to the plate, substantially as described.

3. A rheostat consisting of sections of re sistance each including a metallic body having a winding in electrical contact therewith, means for connecting together the windings of the several sections, contacts carried by the metallic bodies of the sections and a movable element also having contacts placed to coact with the contacts on said sections, substantially as described.

4. In a rheostat, the combination of a series of metallic plates, windings on the plates in electrical connection therewith, metallic lingers in electrical connection with the plates and a movable element placed to engage said fingers. substantially as described.

5. In a rheostat, the combination of a series of supporting-grids each having a Winding of resistance material, contact-fingers carried by certain of the grids and in electrical contact with the windings thereon, with an element carrying contacts for engagement with the fingers, substantially as described.

6. In a rheostat the combination of a wind ing of resistance material, a series of contactfingers connected thereto at intervals, with a metallic cylinder having a series of contact plates projecting from and in electrical connection with it, substantially as described.

7. The combination of a body ofresistance material having contact-fingers connected to it at intervals, a metallic cylinder having contact-pieces in electrical contact with it, said contact-pieces being provided with washers of insulating material between them and said cylinder, substantially as described.

8. The combination in a rheostat of a frame, a standard thereon, a series of metallic plates having portions in engagement with said standard, windings of resistance material upon the plates, contact-fingers in electrical connection with certain of the plates and with the windings thereon, with an element carrying contacts for engagement with said lingers, substantially as described.

9. A resistance-section consisting of a plate of metal, a winding of resistance material thereon connected at one end to said plate, and

a finger also in electrical connection with the plate and having means whereby it may be adjusted, substantially as described.

10. A section of a rheostat consisting of a metallic plate, a winding of resistance material thereon, means for holding said plate in position on a frame, a finger projecting from said plate in the plane thereof, said finger being in electrical connection with the winding on the plate, substantially as described.

11. The combination in a rheostat of a supporting ,frame, a series of plates thereon, windings of resistance material on the plates and in electrical connection therewith, with means for connecting together the windings of adjacent plates and means for insulating said plates from each other, substantially as described.

12. The combination in a rheostat of a series of plates having means for retaining them in position and contact-fingers projecting from them, a resistance'material wound on said plates and connected to said fingers, with a rotatable cylinder having its axis parallel to the axis of the series of plates and contact-plates on said cylinder for engagement with said fingers, substantially as described.

13. A resistance -section consisting of a metallic grid, with a contactfinger mechanically attached to and in electrical contact with said grid, substantially as described. 14:. A rheostat consisting of aseries of grids formed of electrically conducting material,

means for electrically connecting said grids together, contact-fingers connected directly to the grids and contacts for coacting with said fingers, substantially as described.

15. A resistance-section including a metallic plate anda contact-piece in mechanical and electrical connection therewith, said piece being constructed to slidingly engage another contact or contacts, substantially as described.

16. A resistance-section including a metallic plate and a contact-finger mechanically and electrically connected therewith, substantially as described.

17. In an electric controller, the combination of a series of contact-fingers with a metallic cylinder having contacts thereon and washers of insulating material between said contacts and the surface of the cylinder, substantially as described.

18. A resistance-section including ametallic plate and a contact-finger mechanically and electrically connected therewith, with means for adjusting the position of said finger relatively to a surface engaged thereby, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ARTHUR c. EASTWOOD.

Witnesses:

C. W. CoMs'rocK, HOWARD O. Town.

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