US1492774A - Rheostat - Google Patents

Description

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Patented May 6, 1924.

UNITED STATES lPATENT OFFICE.

JOHN C. BOYTON, F CLEVELAND, AND HERBERT A. STEVENSON, OF LAKEWOOD, OHIO.

BHFDBTAT.

Application Med Iay 8,

To all whom it may concern.'

Be it known that we, (1) JOHN C. BeY- ToN, (2) HERBERT A. STEvENsoN, citizens of the United States, residing at (1) Cleveland, (2) Lakewood, in the county of Cuyahoga and State of Ohio, have invented a ,certain new and useful Improvement in Rheostats, of which the following is a full, clear, and exact description, reference being had to the accom anying drawings.

T 1e aim of our invention is to improve, simplify, and cheapen the construction of rheostats of the ty e wherein the resistor element is composed) of carbon or like sub stance.

Two very desirable embodiments of our invention are illustrated in the accompanying drawing wherein Fig. I1 shows one form of our improved rheostat in side elevation and as mounted on a su porting member; Fig. 2

is a central longitu inal section through the same; Fi 3 is a front view of the device shown in ig. 1, removed from the supporting member and with the adjusting screw in section; Fig. 4 is a section on the line 4--4 of Fig. 2; Fig. 5 is an elevational view of another form of our invention mounted on a su porting member; Fig. 6 is a central longitu mal sectionon the line 6--6 of Fig. 5 looking in the direction of the arrows; and Fig. 7 1s a section on the line 7-7 of Fig. 6.

The supporting member 1 may be the instrument board of any ap aratus wherewith our invention is adapted or use.

The form of the invention illustrated in Figs. 1 to 4 comprises a tube 2 of insulating material, such as fiber, and to the ends of the tube are applied metal ferrules 3 and 4. These ferrules may be secured to' the tube in anyl suitable manner, as by the obvious expedients of s inning them thereon, indenting the ferru es so as to interlock them with a part of the tube, or they may be secured b suitable fastening means, as b rivets 5. t is essential, however, that they securely attached to the tube, and that they be spaced apart suiciently to insure effective insulation of one from the other. A plate 6 closes the outer end of the tube 2 and is held in place by lugs 7 that extend from the end of the ferrule 4 through slots in said plate and are turned over therebeyond. The plate is extended at one side where it is formed with an internally threaded boss 8 for the reception of a terminal screw 9 by means of 1922. Serial Fo. 558,125.

which an electrical conductor 10 may be attached to the plate.

A supporting plate 12 is similarly secured to the ofpposite end of the tube 2 by lugs 13 of the errule 3 that are projected through slots in said plate 12 and turned over therebeyond. The supportin plate is shown as extended an appreciabe distance on opposite sides of the tube 2, and the extended portions are provided with apertures through which screws 14 pass by means of which the rheostat is secured to the support ing member 1. One end of the supporting plate 12 is turned laterally where it is provided with an internally threaded boss 15 for the rece tion of a terminal screw 16 by means of w ich an electrical conductor 17 may be attached to said plate.

It will be seen from what has so far been described that the plates 6 and 12 constitute the terminals of the rheostat, and that they are insulated from eachother by the tube 2. These terminal plates are adapted to be electrically connected through a resistor element of variable conductivity which we shall now describe.

A series of carbon, preferably graphitic carbon, disks 20 are adapted to be compresed with varying degrees of pressure between the plate 6 and apressure plate 21 as by means of an adjustin screw 22 that is threaded throu h a thimle 23, applied to the supporting p ate 12, the inner end of the screw being tapered to fit within a correspondingly shape depression in the center o the pressure plate 21. The outer end of the screw 22 is equipped With a knob 24. The supporting member 1 has an aperture 25 for the aecommodation of the adjusting screw. 'lo prevent undue separation of the several disks 20 and the pressure plate 21 when the adjusting screw is retracted, to open the circuit (in which case the device serves as a switch) and to revent their dislodgment from the tube 2 1n the event that the supporting plate 12 is removed, a sleeve 26. preferably of insulating material, is pressed into the end of the tube 2 `to form a shoulder -Wherewith the peripheral portion of the pressure plate 21 may engage.

The form of the invention illustrated in- Figs. 5, 6 and 7 is made up of a sleeve 3() of suitable insulating materlal which, in this form of the invention, may be fiber, glass, porcelain, or other suitable insulating ma- .contact with said member.

terial, and a sleeve 31 is fitted into one end of the tube to provide a shoulder. Between this shoulder and the opposite end of the tube repose the carbon disks 32 engaged at each end by substantially identical pressure plates 33 having central projections 34. The projection of the pressure plate 33 adjacent the sleeve 31 4tits within a recess in the end of an adjusting screw 35 which has a knob 36 applied to its outer end. The adjustmg screw is threaded through a supporting plate 37, shown in the present instance as circular, and secured to the supporting plate 37 on opposite sides o the tube 30 are the outwardly turned ends of a substantially U-shaped member 38 which has its central branch engaged across the outer end of the tube 30 and perforated to receive the projection 34 o the adjacent pressure plate 33. Screws 40 and 41 connect the ends of the U-shaped member to the supporting plate 37, and these screws are insulated from the supporting plate, while being in electrical The screws 40 and 41 have nuts 4Q applied to their threaded ends, and the screw 40 is sufficiently long to receive a knurled nut 43 so that a binding post is thus constituted of the.screw 40 to which an electrical conductor 44 may be applied and clamped between the nut 43 and the adjacent nut 42. Said conductor, therefore, is in electrical connection with the pressure plate 33 at the outer end of the series of carbon disks 32, while the pressure plate at the opposite end of said series has electrical connection, through the adjusting screw 35, with the supporting plate 37. The supporting plate 37 is spaced from the supporting member 1 by a bar 48, that is interposed between the two and through the ends of which the screws 46 and 47 pass, to provide clearance for the heads of the former screws 40 and 41. The respective screws 46 and 47 have nuts 50 and 51 applied to their inner ends, and the latter screw is made sufiiciently long to receive a knurled nut 52 between which and the nut 51 the end of an electrical conductor 53 may be clamped. The last mentioned conductor, therefore, has electrical connection with the series of carbon disks through the screw 47, supportinF plate 37, adjusting screw 35, and the adjacent pressure plate 33.

It will be readily understood from the foregoing description that in each embodiment ot the invention current flowing from one of the electrical conductors to the other may be varied by altering the pressure imposed upon the carbon disks by means of the adjusting screw, in accordance with the well known principle of carbon rheostats.

Having thus described our invention, what we claim is:

1. A rheostat of the character described comprising a tube of insulating material, an

element fastened to and closing each end of the tube, said elements being of conductive material and insulated from each other by the tube, a pressure screw threaded throng one of the said elements, a pressure plate applied to the end of the screw, a series of carion disks interposed between said pressure plate and the element which closes the opposite end of the tube, and means for connecting electrical conductors to the aforesaid elements.

2. A rheostat of the character set' for' comprising a tube of insulating material, a sleeve pressed into one end of the tube thereby to provide a shoulder, an element of conductive material closing each end of the tube, said elements being insulated from each other by the tube, an adjusting screw threaded through one of the elements and projecting into the tube, a pressure plate applied to the end of the screw,

said plate being limited in its outward movement by said shoulder, a series of carbon disks interposed between said pressure plate and the element situated at the other end of the tube, and means for connecting electrical conductors to the aforesaid elements.

3. A rheostat of the character set forth comprising a tube of insulatin material, a ferrule secured to each end o the tube, a

plate of conductive material applied to each end of the tube, each fel-rule and the adjacent plate having interlocking parts whereby the plates are secured to the tube through the intervention of said ferrules, means for connecting electrical conductors to said plates, a screw threaded through one of said plates and projecting into the tube, a pressure plate applied to the inner end of the screw, and a series of carbon disks interposed between said pressure plate and the plate situated at the opposite end of said tube.

4. A rheostat of the character set forth comprising a tube of insulating material, a ferrule fitting over and secured to` each end of the tube, said ferrules having lugs extending from their .outer ends, a plate applied to each end of the tube, said plate having apertures through which the lugs of the adjacent. ferrule extend and beyond which the lugs are turned over thereby to secure the plates to the tube, one of said plates having a threaded hollow boss, a pressure screw threaded through said boss and projecting centrally into the tube, a pressure plate within the tube, said pressure plate and the inner end of the screw having part-s interengaging with each other, a series of carbon disks interposed between the pressure plate and the plate situated at the opposite end of the tube, a sleeve fitted into the end of the tube into which the screw projects, the sleeve providing a shoulder against which the pressure plate may enage when the screw is retracted, and means or attaching electric 4kconductors tothe plates that are applied to the ends of the sleeve. y

5. A rheostat of the character set forth comprising a tube of insulating material,

aplate secured to and closing one end of the tube, said plate having a lateral extension,

means .for connecting an electrical conductor to said extension, a plate secured to and closing the opposite end of the tube, said plate extending in opposite directions beyond the tube thereby to provide support ing ears, the plate extending beyond one of said supporting ears and turned laterally to form a lug, means for connecting an electrical conductor to said lug, a screw extending into the tube through the last mentioned plate and having threaded connection therewith, a pressure plate applied to the inner end of the screw, and a series of carbon disks interposed between the pressure plate and the first mentioned plate.

6. In a rheostat of the character set forth, the combination of a supporting plate, a U-shaped member having its ends secured to and insulated from diametrically opposed portions of the supporting plate, a tube of insulating material reposing between the side branches of the U-shaped member and confined between the central ortion thereof and the opposed portion o the supporting plate, a variable pressure means. carried by t e supporting plate and extending into the tube, a compressible body -of resistance material within the tube and interposed between said means and the central portion of the U-shaped member, and means for connecting an electrical conductor to'eacli the U-shaped member and the supporting plate.

7. In a rheostat of the character set forth, the combination of a supporting element, a U-shaped member having its ends connected to and insulated from the supporting member, a tube of insulating material reposing between the side branches of the U- shaped member and confined between the supporting element and the central. portion of the U-shaped member, said central portion having an aperture in axial alignment with the bore of the tube, a screw threaded through the supportinglelement and projecting into the tube and aving a recess in its inner end that is substantially in axial alignment with the bore of the tube, a series of carbon disks, a pressure late applied to each end of said series of disks, each pressure plate having a central projection, the projection of one of said plates being engaged throu h the aperture in the central portion of t e U-shaped member and the projection of the other engaged within the recess of the screw, and means for connecting an electrical conductor to each of the U-shaped member and the supporting element.

8. In a rheostat of the character set forth, the combination of a supporting element, a U-shaped member having its ends turned outwardly, screws connecting the ends of said member to diametrically opposed portions of the supporting element, means insulating the member from the supporting element, one of said screws constituting a binding post through which a conductor is radapted to have electrical connection with ,tor lis adapted to have electrical connection with the supporting element, a tube of insulating material reposing between the side branches of the U-shaped member and confined between the central portion of said member and the supporting element, an ada justing screw threaded through the supporting element and projecting into the tube, and a compressible body of resistance material confined between the inner end of the screw and the central portion of the U-shaped member.

In testimony whereof, we hereunto alx our signatures.

JOHN C. BOYTON. HERBERT A. STEVENSON.

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