US1445678A - Rheostat - Google Patents

Description

A. C. GILBERT.

'Feh zo, 1923.

RHEOSTAT.

,man nuuhza. 191s.

2 SHnETS-SHEET l.

frz venten' @45 MQW Feb. 20, 1923. f 1,445,678. A. C. GILBERT.

' RHEosTAT.

,FILED JAN.248| 19H3. 2 SHEETS-SHEET 2.

, orney Patented F eb. 20, 1923.

UNITED STATES ALFRED C. GILBERT, 0F NEW HAVEN, CONN lCOMPANY, OF NEW HAVEN. CONNECTIC ECTICUT, ASSIGNOR TO THE A. C. GILBERT UT, A CORPORATION OF CONNECTICUT.

RHEOSTAT.

Application filed January 28, 1918. Serial No. 214,141.

T0 aN y'1o/1.0m. 1,'/5 may com/'ern Bc it known that I, .fiiirnnn C. GiLnEnT, a citizen of the United States, residing in the city and county of New Haven and State ot Connecticut, have invented certain new and useful Improvements in llheostats, of which the following is a full, clear, and cxact description.

This invention relates to rheostats, and it has particular reference to a small, cheap rheostat construction primarily designed for use in the hollow base portion of an electric fan. although my improvements are applicable to other apparatus where simple and economical means for controlling the speed ot a motor or the like are required.

The primary object is to furnish :in efficient and reliable rheostat which can be produced at minimum expense.

Another object is to provide improved means for mounting the rheostat on a suitable base plate, which may be the plate that encloses the open bottom portion` of a fan base.

To these and other ends, the invention consists inthe novel featuresand combinations of parts to be hereinafter described and claimed.

In the accompanying drawing:

Fig. 1 is a side elevation of a fan base, having a rheostat embodying my improve ments;

Fig. 2 is a bottom view of the fan base;

Fig. 3 is a side elevation of the rheostat and its base plate,'the hollow casting or standard of the fan being indicated `in dotted lines; f

Fig. 4 is a side elevation oi the taken at right angles to Fig. 3;

Fig. 5 is a top plan view of the parts shown in Fig. 4, showing the controlling lever in the position in which the flow ot' current is interrupted;

Fig. 6 is a vertical central section of the rheostat;

F ig. 6^ is a section of certain parts shown rlieostat,

in Fig. 6 on a larger scale;

Fig. 7 is a horizontal section taken beneath the insulating plate or platform, on which the contacts are mounted, looking upward;

Fig. 8 is a diagram of the electrical connections; and

Figs. 9 and 10 are top and bottom views respectively of the controlling lever.

In the drawings, my improvements are illustrated as applied to a. base for a small electric fan, which base is indicated generally by reference character A, and comprises usually a hollow standard 11 of cast metal having a lower open end which is closed by a sheet metal plate 12 secured thereto by screws 13. The plate 12 isused as a base plate for a rheostat designated generally by reference character B, which rheostat is housed in the hollow bottom portion of the fan standard or base and carried by and removable with the' base plate. The rheostat B embodies in itsconstruction a controlling lever 14, projecting laterally through a slot 15 at one side of the hollow member 11. In the particular example shown, this lever has three main ositions, one corresponding to the total 1nterruption of the current, a second corresponding to a half speed operation of the fan, and a third corresponding to a full speed operation thereof.

The rheostat comprises in its construction an insulating plate orplatform 15, which may advantageously consist of a fibrous insulating material, and, in the example shown, this plate serves as a mounting for the controlling lever 14 and for two vfixed contacts 16, 17, cooperating therewith. The plate 15 is supported by integral lugs 18. struck-up out of the sheet metal plate 12 yand having reduced upper extremities 18 which pass through slots in the insulating plate. said extremities 18 being thereafter twisted out of the planes of the main portions of the lugs, as shown more particularly in Fig. 5, so that the insulating plate is firmly clinched on top of shoulders atl the upperportions of the lugs. The pivot of the controlling lever 14 is located intermediate and substantially in line with the lugs 18, and it preferiably comprises a member 19 in the form of a bolt having a head 20 disposed beneath the insulating platform, the shank of said bolt passing through an opening in the plat form to a considerable height above the latter, as shown in Fig. 6. Between the bolt head 20 and the under surface of the insulating platform is a Washer 9.1, and a simi lar washer 22 is interposed between the upper surface of the platform and the under surface of the controlling lever 14. The pivot bolt passes through the controlling out of the slot 15.

lever at a point intermediate of its ends, for which purpose said lever is provided with a suitable opening, said opening, in the ex ample shown, being` located somewhat nearer the contact end (cooperating with contacts 16, 17) than the operating end projecting On top of the controlo ling lever, another washer 23 emiraces the bolt and on top of this washer is a nut 2l, by which all the parts are firmly held in place,

so as to provide a mounting for the controlling lever which is neither too tight nor too loose. Preferably, the nut 2a will be mutilated after the, parts assembled, so that it cannot be displaced on the bolt, whereby the proper adjustment of the lever relatively to its support will be maintained.V

ln addition to the functionof pivotingl or swiveling the controlling` lever, the bolt 19 serves to carry the current, as hereinafter pointed out, and it likewise serves as a mounting for the resistance element, which is preferably constituted by. a sleeve 25 of some suitable resistance material having a vitreous coating, said sleeve having outwardly extending wire connections at the upper and lower parts thereof, so that a re duced.` flow of current will pass through it when the respective connections are ,connected with opposite poles of a source of current. p However, while `it is advantageousito use a resistance element ofl ceramic material in the form of a sleeve, 1 do not limit myself in this respect. ln the form shown, the resistance sleeve, which is suitably insulatedvby its covering or coating, is supported by the ,connecting wires, which are rather stiff, and the bolt 19 merely serves to center it. `One connecting wire 26 extends fromy thecontactl to one end of the sleeve and is suitably connected to it (in this case the upper end, as shown in Figf), while another wire 27 extends from the contact 17 to the otherv (lower) end ofthe sleeve, to which it is suitably connected. rlhe con- Ftaots 16, 17` may advantageously consist of headed fasteners of \'vell-lrnown type, having their heads disposed on the upper surface of platform 15 and provided with bendable shanks 16e, 17 extending through openings in the platform and clinched over on the under surface of the latter. 'In the particu lar exampleshown, the wires 26,' 27 are soldered to the ends of. the flexible contact shanlts, which are bent up'over the edge of the platform, as-shown in Fig. el. The shank ofeach contact is made intwoparts that can be separated from 'each other, as inthe ordinary McGill fastener; i

The-electrical connections are as follows: One wire 28ooming inifrom the battery, or other-'current source, passes through an insulating. nipple 29, in the side wall of member A and passesupward in said member to the motor (not shown) mounted on top of the same. `From the motor, a return wire 30 comes down into the hollow base member through the open upper end thereof, and is connected, as by soldering, with the upper end of the bolt 19, as shown at 31 in Fig. 3. A return wire tothe battery, or other current source, is connected to the shank of contact 17, said wire being designated by reference character 32, and passes out of the hollow base through the nipple 29.

lt will be observed that the lug ends 18 are so located as to constitute stops for limiting the swinging movement of the controlling lever in opposite directions (Fig. 5). This is a factor of some importance in facilitating the assemblage of the parts and the testing of the rheostat unit before it is placed in the fan base. When the rheostat has been placed in the base, however, the end portions of the slot 15 properly limit the movement of the lever. This lever is preferably of composite construction, having a main portion 14 of fibrous material and a metal Contact portion 14, preferably of brass. The metallic portion 14. extends somewhat beyond the pivot of thclever and is in fullcontact with the metal washers above and below the lever, which, in turn, contact with the bolt shank so that the cur rent will pass properly from the bolt to the movable contact 14 or'vice versa. The opshown in Fig. 5, the flow of current isentirely interrupted, owing to the fact that there is no connection between the wires 28, 32. l/Vhen the lever is' moved so that its contact portion 1e is in contactwith the head of contact 16, the current, it can be assumed, passes into the motor by wire 28, out of the motor by wire 30 and bolt 19 to contact 14', into contact4 16, thence through the resistance 25 by wires 26 and 27 to Contact 17, and thence to the current source by wire 32. is the current passes through the resistance element, the speed of the fan or other device is cut down to `an extent corresponding to the amount of resistance interposed- Then the lever is `movedso that its contact port-ion 14 is in contact with the head of contact 17, the current is shunted about theresistance in an obvious manner and the motor operates at full speed.

ln practice, the various wires vor leads should be properly enclosed, and insulated to prevent short. circuiting, as Ywill be ob vious. o Y

The particular manner of fastening the contact portion 14 to the fibrous body porlill) The opening 14" for the pivot bolt is formed partly in the metal part and partly in the Vfibrous part.

Fig. 8 shows a simple diagram of the electrical connections, including the motor, which is designated by M, the resistance 25, the fixed contacts 16 and 17, and the movable contact 14".

Various changes may be made in the details without departing from the scope of the invention as defined in the claims.

What I claim is:

1. In a device such as described, a sheet metal plate having struck-up lugs, a platform supported on said lugs, and a rheostat structure on the platform.

2. In a device such as described, a sheet metal base plate having struck-up lugs, a platform of insulating material supported on said lugs, and a rheostat structure mounted on said platform.

In a device such as described, a sheet metal base plate having struck-up lugs, a platform of insulating material supported on said lugs, and a rheostat structure mounted on Said platform, including at least two fixed contacts on the platform and a movable contact to cooperate successively with said fixed contacts.

4. In a device such as described, a base plate, a platform of insulating material spaced above the same but carried thereby, a l vbolt passing through an opening in the platform, a controlling lever of insulating material pivoted to the platform by means of said bolt, a conductor strip secured to a face of said lever, and a fixed contact cooperating with said conductor strip.

5. In a rheostat, a base plate, a platform of insulating material spaced above the same but supported thereby, two xed contacts on said platform, a resistance element connected with said contacts, a controlling lever formed of insulating material pivotally mounted upon said platform, and a contact strip secured to said lever and movable thereby to electrically connect either of said fixed contacts with said pivot.

(5. In a rheostat, a plate of insulating material, fixed contacts on said plate, a resistance element connected with said contacts, a controlling lever formed of insulating material and pivotally mounted upon said plate, and a Contact strip secured to a face of said lever and movable thereby to electrically connect any one of said fixed contacts to said pivot.

7. In a rheostat, a plate of insulating material, fixed contacts on said plate, a resistance element connected with certain of said contacts, a controlling lever pivoted on said plate and common means to pivot said controlling lever and support said resistance element on said plate.

8. In a rheostat, a supporting plate or platform, a pair of fixed contacts supported thereon, a lever pivotally mounted thereon and having a Contact member cooperating with said fixed contacts, a resistance element in circuit between said contacts and mounted above said lever and common means for pivoting said lever, centering said resistance element and forming an electrical connection with said Contact member.

9. In a rheostat, an insulating plate, a pair of fixed contacts carried thereby, a pivotally mounted movable contact cooperating with the fixed contacts, and a resist-- ance element bridging said fixed contacts and mounted above the pivot point of said movable contact about an electrical terminal of said rheostat connected with said movable contact.

10. In a rheostat, a base, a switch lever pivotally mounted thereon, a resistance element, adapted to be controlled by said lever, said lever being mounted between said base and said resistance element and com` mon means for pivoting said lever and retaining said resistance element.

11. A rheostat comprisin an insulating base having fixed contacts t ereon, a resistance element bridging said contacts, a pivoted handle carrying a contact member cooperating with said fixed contacts and means to electrically connect said contact member with a terminal of said rheostat and to retain said resistance element upon said base.

12. In a rheostat, a base, a Switch lever pivotally mounted thereon, and a resistance element adapted to be controlled by said lever, said resistance element being mounted above said base and said lever upon the terminals leading thereto and positioned thereon by a terminal connected with said lever.

In witness whereof, I have hereunto set my hand on the 21st da of Januar 1918.

ALFR JD c. GILRT.

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