US1658866A

US1658866A - Vernier rheostat

Info

Publication number: US1658866A
Application number: US562607A
Authority: US
Inventors: Chester H Thordarson
Original assignee: Individual
Current assignee: Individual
Priority date: 1922-05-22
Filing date: 1922-05-22
Publication date: 1928-02-14
Anticipated expiration: 1945-02-14

Description

Feb.14, 192 8. f 1,658,866

- c. H. THORDARSON VERBIER RHBOSTAT Filed May 22. 1922 Patented Feb. 14, 1928.

UNITED- STATES CHESTER H. THORDARSON, OF CHICAGO, ILLINOIS.

VERNIER RHEOS'IAT.

Application filed May 22,

This invention relates to improvements in rheostats for regulating or adjusting an electrical circuit, and refers more particularly to a novel vernier' rheostat, the circuit of which composes a main winding, constituting almost the entire rheostat circuit, and a short or fractional part compris ng, 1n length, a short subdivision of said entire circuit and which is in circuit with said winding and binding posts for connection to an external circuit, and containing also a main sliding element which travels over and in contact with the main winding or its contacts and a secondary sliding element which travels'independently of the main sliding element over the fractional circuit part, whereby the latter element or member is capable of cutting in or out fractional portions between one or more coils or contacts of the main winding so as to thereby attain very minute subdivisions of the rheostat circuit.

An object of the invention is to provide an exceedingly simple and eflicient rheostat of this character, in which the parts may be economically made and economically assembled, and also to provide a construction in which the fractional portion of the circuit is well insulated from the main winding of the rheostat circuit.

A further object of the invention is to produce a construction of rheostat in Which the operative parts are compactly arranged and protected by the general construction of the device from exterior bruises.

The construction herein shown is particu-' larly well adapted for use in the tuning circuits of radio transmitting and receiving sets but may be adapted to other uses where fine graduations of current flow through a circuit is required.

The invention consists in. the combination and arrangement of the parts shown in the drawings and described in the specification, and is pointed out in the appended claims.

In the drawings:

Figure 1 is an end view of a rheostat embodying my invention.

Figure 2 is an axial section thereof, with parts shown in elevation.

Figure 3 is a diagram of the rheostat circuit.

Figure 4 is a modified diagram of the rheostat circuit.

Referring first to Figure 3, 10 designates a winding constituting the principal part of 1922. Serial No. 562,607.

the rheostat circuit. 11 designates a fractional part of said circuit which, in practice, is made of a lengthof approximately that of one or two of the coils of the winding. 12 designates a conducting arm which is adapted to travel along the length of and in contact with the winding 10, and 13 designates a like (conducting arm which is adapted to travel along and in contact with the fractional circuit part. Said arms are shown in Figure 4 electrically connected, as at the point 14. 15, 16 designate binding posts by which the rheostat circuit is connected to the wires of an external circuit. The said.

arms

12, 13 are, in the mechanical construction, mounted to rotate on the same axis, and each of said arms is adapted to be independently movable so that, with the arm 12 on one of the coils or contacts of the winding, the other arm 13 can be moved along the fractional circuit part 11, so as to divide the current force into as many in crements as the length of said fractional conductor bears ratio to the length of the coil or coils with which the arm 12 is in contact.

Referring now to the illustrated mechanical construction constituting one embodiment of my invention, 17 designates a metal base plate. It is provided with a rim 18 which is made of one piece of metal that is curved to form an almost complete circular element that may be fixed to the plate 17, as by means of an integral spur or flange 20 struck up from said base plate and riveted to the ends of the rim member. The said rim is shown as made of thin gauge metal and is of a width to form a protecting wall for parts enclosed therein, as will hereinafter be described.

The said rim also forms a core or support for the winding 10 of the rheostat circuit, said winding being Wound in elongated coils about the said rim throughout the principal portion of its circumferential length. The Winding is insulated from the metal of the rim by an insulating tube 21 made to fit closely about the portions of the rim at the sides of the flange or spur 20 and directly supports the winding 10.

22 designates a disc made of insulating material which is seated on the base 17 and is enclosed by the rim 18 and its winding 10. Said insulating disc 22 at its base is made the full diameter of the rim, and is formed at said base with a radial extension or flange 24 that extends beneath the winding to insulate the winding from the base 17. The disc 22 is provided near its edge remote from the flange 24 with an external annular groove 25 in which is seated the fractional portion 11 of the rheostat circuit,

. said fractional circuit part being a plain curved wire. tion is connected at one end to the binding post 15 and is laid between its ends in said external groove 25 and is open at its other end. The 'coil 12 is connected at ome end with the binding post 16 and is open at its other end, the fractional circuit part and winding being thus in series through the

arms

12 and 13. Said disc 22 is provided exterior to said groove 25 with an annular recess or groove 26 of some depth, and the latter groove is flanked by an annular en closing flange 27 of less height than the thickness of said disc. I

28 designates a hollow operating shaft which extends through mounting board B, in which the shaft is rotatively mounted. Said shaft is reduced at its inner end and is rotatively mounted in a sleeve 28 which extends through the base plate. Said shaft extends beyond-the disc 22 and carries at its outer end the angularly adjustable conducting arm 13 which extends radially from the shaft. Said arm 13 is provided at its free end with a down-turned contact finger 30 for engagement with the fractional circuit part 11. Said contact finger 30 also travels in the groove 26 to hold it engaged with the fractional circuit part 11 and also to prevent contact of said downturned finger with the winding 10. Said hollow shaft isprovided with a hand wheel 31 by which to rotate it-and the conducting arm 13.

32 designates a second shaft which extends through and is mounted to rotate in the shaft 28. Said second shaft extends outwardly beyond the hollow shaft28 and is provided beyond the hand wheel 31 of the shaft 28 with an independently'actuable hand wheel 33. The shaft 32 also extends at its inner end beyond the shaft 28 and carries at its inner end the contact arm 12 which is disposed radially to the shaft and is adapted for contact at its outer end with the coils of the windinglO.

As herein shown, the conducting arm 13 is fixed to a reduced, threaded portion of the shaft 28 by being provided with an enlarged perforated head for the passage of said reduced end, and the said head is clamped between a solid washer 34 and a nut 35 threaded to saidshaft. The Washer 34: is forced by the nut 35 against a split or spring washer 36, which latter yieldingly bears on the inner end of a flanged sleeve 28', which surrounds the shaft 28 at the disc and constitutes a bearing sleeve for the Said fractional circuit porlatter shaft. The said conducting arm 12, is likewise provided with a perforated head through which the threaded, reduced, inner end of the shaft 32 extends, and said arm is held fixedly on said" shaft between lower and

upper nuts

38, 39. The metal to metal contact of the mounting of the conducting

arms

12 and 13 and their fastening nuts and bearing of the shaft '32 in the hollow shaft 28. Thus, with the outer end of the conduct ing arm 12 in contact with one or more of the coils of the windinglO, the conducting arm 13 can he angularly adjusted on the fractional circuit part 11, so as tofurther subdivide. the current passing through the rheostat, due to the length of said fractional circuit part relatively to the length of the coil or coils of the winding with which the conducting arm 12 is in closed circuit.

The said base plate 17 maybe attached to the inner face of a mounting board B which, in practice, may be a wall of-a cabinet or like structure in which the electrical apparatus to beregulated by the rheostat is contained. The fastening of the plate 17 may be effected by means of screws 22' extending through said plate and the conducting disc into said wall. The hand piece .31 of the outer or tubular shaft 28 is spaced from said mounting board a distance to permit it to be readilygrasped to turn the same and the conducting arm actuated thereby, and the hand piece of the shaft 32 is spaced from the hand piece 31 to afford free access thereto without disturbing the latter hand piece. t

An advantage of .the construction shown is" that the winding 10 and the fractional portion 11 of the circuit are arranged con The conducting elements of the rheostat,

embracing the winding 10, the fractional circuit part 11, the

wiping conducting arms

12 and 13 and their mounting, as well also as the insulating disc 22, and the rim 18. are made of materials which are not afiected by heat developed in the circuit conductors, so that thereby, after the parts have been assembled and adjusted, the accuracy of the on said rim at one end of the winding 10 to prevent contact of the conducting arm 12 with one of the binding posts. A like stop may be provided on the disc to limit angular movement of the other conducting arm 13.

In Figure 4 is shown a modified wiring diagram, wherein the winding 10' and short circuit part 11 are in direct series and connected to binding

posts

15, 16, and wherein the

arms

12, 13'.are not directly in series with the coils and circuit part and are represented as electrically connectedhy the Wire 14. i a

I claim as my invention:

A Vernier rheostat comprising a base, a rim outstanding therefrom and fixed thereto, an insulating body within said rim,

formed on its circumference with a groove and radially beyond said groove with a guard flange, a conductor embracing a winding on and insulated from said rim, and a fractional circuit part fitted in said body groove, and electrically connected conducting arms mounted for separate angular adjustment about an axis concentric to said rim, adapted for wiping contact, one with said winding, and the other provided with an inturned finger lying outside said body periphery for wiping contact with said fractional circuit part, and lying within said guard flange.

In witness whereof I claim the foregoing as my invention, I hereunto append my sig= nature this 17 day of May, 1922.

CHESTER H. THORDARSON.