US1618967A - Rheostat - Google Patents

Description

- March 1 1927.

H. E. ADAMS RHEOSTAT Filed Sept 14. 1925 Will afro: "u r The . the hollow of the extension spaced Patenta& Mar. 1', 1927.

&UNITED sTATEs 1-,6s,967 PATENT. OFFICE;

EABBY E. ADAMS, OI' TOLEDO, OEIQ ASSIGNOB TO THE W. G. NAGEL ELECTBIC COM- P ANY, OI' TOLEDO, OEIO, A COROBATION OF 0310 annosmr.

Application filed September 14, 1925. serial No. 53,114.

This invention relates to electrical equipv ment and particularly to rheostat umts.

Inthe use of units of this character in connection, for instance, with instruments for' 5 indicating the level of liquids it is important to tightly seal the chamber containing the rheostat Contacting parts, and in doing so the leads from the outside terminal wires must be brought into the chamber in a sealed manner to prevent leakage therearound.

It is the object of this invention to provide a chamber means :for this purpose, which 'is easy and quick to install, is inexpensive to manufacture and composed of few parts.

The invention is fully described in. the following specification, and while in its broader aspect itiscapable of embodiment forms and-in different connecin numerous tions, a ,preferred embodiment thereof in connection wi h a rheostat unit is illustrated in the accompanying drawings, n which,--;

Figure 1 is a top" plan view of such unit with the covers removed and the parts broken 'awa Fig. 2 is a section on the line 2-2 in ig. 1. Fig. 3 is a section on the line- 3-3 in Fig. 1. Fig. 4 is a perspective view of the lead connections and carrying strips therefor in assembled relation and. with parts of the strips broken away. Fig. 5 is a perspective View of one of the strips; Fig. 6 is a perspective view of'one of the terminal clamping members, and Fig. 7 is a per- `spective view of the spring lead finger extending from one of the lead connectons to -the swinging contact arm'of the rheostat.

Referrin shallow ca'sng or frame of substantially cylindrical form in the present instance, and having' ahollow extension 2 at oneside anda shenk orarm 3 projectin from its bottom substantially axially oft e body part 1.art 1 is hollow to form an open top chamlier 4, whichsis circular in form and in communication through anopen neck 5 with 2. A segmental resistance unit 6 is mounted concentrically in the-chamber 4 with the opening between its ends in register with theneck openin 5 `and having' any suitable arrangement o Contacts,

constitute the sucoessively spaced stan'ce, 7

convolutons ofthearesistance wire 8 is jqurnaledin the c to the drawings, 1 designates a 'ngs being which, in thepresent in-' swingingarm 9 having, in the resent instance, a contact plunger 10 in S iding outu ward spring-thrust engagement with the inner periphery of the resistance coil =7. The plunger 10 has sliding radial movement in a socketed conductr part 11 of thearm 9 and this part has astud 12 projecting therefrom in exposed position axially of the swinging ax'is of the arm and at the side thereof exposed to theshaft 8. If the rheostat unit is used in connection with a liquid level indicatinginstrument, the shaftS may be connected to and actuated by the movement of a float ridin on the liquid, the level of which is to %e determined. The manner of actuating the swinging contact arm, however, forms 'no part of the present invention and is, therefore, not shown.

Lead wires for therheostat control circuit are intended to enter the outer open end of theextension 2 and` to be engaged to lead' connecting bars 13-13 byterminal clamping screws 14, said lead bars being projected through the neck opening 5 and into the chamber 4 of the casng, and one being connected to one terminal` end of the resistance' coil 7 by binding' screw 15, while the other has a spring lead finger 16 mounte'd on its inner' end by a'binding screw 17. The free end of the finger 16 bears on and makes electrical contact with the outer end of thestud 12, which projects axially from the swing- -ing contact arm of the rheostat The .two connecting bars are carried'in parallel spaced relation by the two laterally spacedpartition members 18 of insulating material. These partition members preferably comprise strips of vulcanized fibre which fit -at their ends and lower bottom edges intorecesses 19 provided therefor n the side and bottom walls of the neck opening 5, thestrips 18 being adapted to be slidingly placed into said recesses, as shown n Figs. 1 and 2. The connectingbars 13 are projected throug respective openi 20 provided throug 'thestrps 18, such open-` of suitable size and shape to fit the end portions of the bars projected therethrough. The bars are prevented from endwise movement with res ect to the carrying strips' 18 when in assem led relation thereto by saidenlargements 21 provded on the strips s, best hw in Fig. 4.

When a set ofbars 13 and insulated carrying-strips ormembers 18 have been assembled in proper relation, as shown n Fig. 4, they are inserted as a unit nto thenck portion 5 of thecase 1 with the ends and bottom edges of the strips fittng into therecesses 19 of the case. This having been done, the pocket or space between the insulating strips -18 and around the central 1nterposed portions of theconneeting bars 13 is filled with a material 22 (F ig. 2) 'whch is of an electrical insulating nature and sufliciently fluid when appled to completely fill said space and to enter any crevices, Cracks or openings therein so as to cooperate with thestrips 18 andbars 13 to form an hermetic seal between the rheostat chamber 4 and the wire terminal receiving chamber 2' in theextension 2. Thematerial 22 should preferably be of'such a nature' as to become at least partially set so as to maintain its shape after being applied. This material should also be-of a nature to prevent being attacked or disintegrated by or to render it insoluble in the liquid, the level of which is being determined, as in most applications thecasing 1 would be mounted in an opening. in the container and theextension 3 thereof projected into the container, thereby rendering it possible in some cases for the liquid in the container entering the chanber 4. In some cases air pressure is applied to the liquid within the container to force it to a point of use,'and this pressure sonetimes might enter the chamber 4, and it is, therefore, one of the purposes of the seal between such chamber and 'the wire terminal chamber 2' to prevent the leakage of such pressure' therebetween. In some cases an insulating shellac may be employed as thematerial 22, and in other cases where gasoline or other hydrocarbon liquid is to be gauged a compound composed of glycerine and corn starch in substantially the proportion of two pounds of the former to four ounce's of the latter, thinned with water and boiled to a jelly-like consistency has been found suitable for use. This latter material forms the subject-matter of a copending application and is, therotore, not claimed herein.

The tops of the chanbers 4 and 2' are closed bycovers 23 and 24, respectively, secured to the casing top byscrews 24 or in any other suitable manner. Thecover 23 has a sealing or gasket tight fit o'n the top of the casing and also coacts with the upper strips' 18 and with thetop of the materia therebetween.

I wish it understood that my invention is not limited to any specific Construction arrangement or form of the parts, as t is capable of numerous modifications and changes without departing from the spirit of the claims.

Having thus described my invention, What I claim as new and desire to secure by Letters Patent is: i

1. In a rheostat, a casing forming an open top casing, a cylindrical chamber for receiving rheostat contact parts and having a side opening therefrom, a pair of spaced parallel insulating strips mounted in said opening to close the same, electrical connecting member extending through said strips and the space therebetween, sealing material filling the space between said stri veloping the contact mem Jers, and closure means mounted over said chamber and strips.

2. In a rheostat, a casing having a cylindrical chamber for receivng rheostat conopening having recessed side-walls, insulat-- ing strips slidingly mounted in said recesses to form a double closure for the opening with a pocket therebetween, electrical' connecting members extending through said strips and pocket, a sealing material disposed in said pocket and elosely enveloping the connecting members, and removable cover means for said chambers and opening.

3. In combination, a casing forming a chamber for containing electrical parts and having a side opening leading therefron with spaccd recesses in the opening wall, insulating strips s'lidably mounted in said recesscs and forming transversely spaced closu'e members for the opening said strips having opening therethrough, a terminal connecting lead bar projected through said strip oponings and substantially filling the same and having an enlarged portion in. the space between the strips for sholdoring against the strips, and a scaling material of flowing consisteney when Originally applied disposed in and completely filling the space between said st'ips around said lead.

In testinony whereof I have hereunto signed by name to this specification.

` HARRY E. ADAMS.

s and' closely .en-

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