US2230586A

US2230586A - Resistance unit

Info

Publication number: US2230586A
Application number: US283960A
Authority: US
Inventors: Joseph J Cerny
Original assignee: LECTROHM Inc
Current assignee: LECTROHM Inc
Priority date: 1939-07-12
Filing date: 1939-07-12
Publication date: 1941-02-04
Anticipated expiration: 1958-02-04

Description

Feb. 4, 1941. .1. J. CERNY RESISTANCE UNIT Filed July 12, 1959 720872.22?" Jsgv/z J Cern I Patented Feb. 4 1941 UNITED J STATES RESISTANCE UNIT Joseph J.'Cerny, Berwyn, Ill., assignor to Lectrohm, Inc., Cicero, 111., a co p ration of Ill inois Application July 12, 1939, Serial No. 283,960

6 Claims.

The present invention relates to resistance units and has as its principal, object to improve the construction of wound resistance units so as to so constructed as to aid in the dissipation of heat and to protect the resistance wire against changes in insulation which commonly occur where the protection for the wire is composed of a moisture l5 absorbing material.

The present invention also contemplates certain improvements in the method of manufacturing resistance units whereby a resistance wire and its terminal strips are first mounted on a 20 core piece. The entire unit is then given a coating of porcelain enamel and while wet is encased in a shell of porcelain which is in the form of a split sleeve.

The features and advantages of the present in- 25 vention will appear more fully as the description proceeds, reference being had to the accompanying drawing wherein a preferred form of the invention is shown. It is to be understood, however, that the drawing and description are il- 30 lustrative only, and are not to be taken as limiting the invention except insofar as it is limited by the claims.

In the drawing, Fig. 1 isa perspective view of a resistance unit embodying my invention;

35 Fig. 2 is a sectional view on the line 2-2 of Fig. 1;

Fig. 3 is a perspective view illustrating the resistance wire and terminal strips mounted on the inner porcelain member;

40 Fig. 4 illustrates the coating operation in a somewhat diagrammatic fashion, and x Figs. 5 and 6 are perspective views showing the inner and outer porcelain units. Y

Referring now to the drawing, the present in- 45 vention is embodied in a resistance unit, adapted for use in radio receiving apparatus, television sets and other apparatus of the same general nature. The resistance unit comprises a split sleeve ill of porcelain, the sleeve being somewhat 50 oval in cross section, as shown, a hollow core II, a resistance wire i2 and terminal strips l3 and I4. The space around the core ll within the sleeve I is shown as exaggerated in Fig. 2. Normally this space is just such as to permit as ready insertion of the core H with the resistance wire and terminal strips thereon after they have been dipped in porcelain enamel. In this way it is possible to substantially fill the space around the resistance wire and between the porcelain core and porcelain sleeve. The resistance wire I2 is placed on the core H by holding the core in a suitable chuck and winding the wire thereon. The core II has openings l5 and I6 extending through it and these openings serve to circulate air down the center of the resistance unit and i0 thus-conduct away the heat. They are also utilized in holding the core in the winding chuck. When the resistance wire i2 is wound on the core, the terminal strips i3 and H are placed around the wire at the desired intervals and are clamped in place by small clips I! and i8.- The unit shown in Fig. 3 is then ready to dip in a porcelain enamel and mount in thexsleeve 10. By, using the terminal strips I3 and H, the operator can dip all but the protruding ends of the terminal strips in porcelain enamel and then slide the whole assembly endwise into a sleeve M. I The excess enamel that will hang on to the unit practically fills the space around the core ii and the resistance unit I! within the sleeve Ill. The porcelain enamel serves to bind the sleeve and the core together. This enamel is not a very good insulator, but with the insulation provided by the porcelain sleeve ill, the resistance is well protected from an insulation standpoint. Units of this type have been coated with porcelain enamel in the past, but such a material alone has many defects. It has a tendency in humid atmospheres, when subjected to variations in heat, to crack with small surface cracks commonly termed crazing. By the present invention the enamel is protected throughout almost the entire circumference of the sleeve of the resistance unit. The only place the porcelain" enamel is exposed is along the slot it which is it provided in the sleeve ii) for the passage of the terminalstrips i3 and i4. Since the porcelain enamelis not hardened until after the core and resistance wire are mounted in the sleeve it,

there is, of course, no cracking or damaging. of

its surface in the assembly operation.

From the above description, it is believed that the construction and operation of my invention will be readily apparent to those skilled in this art. Having thus described my invention, what I claim as new and desire to-secure by Letters Patent is:

1. A resistance unit of the character described comprising a hollow coreof porcelain, a porcelain sleeve having a narrow longitudinal slot, said said core,

sleeve enclosinz said core, a resistance wire on said wire and projecting through the slot in said sleeve, the space within said sleeve about the wire said core, spaced'te 11'1"};

terminal strips and core being filled with porcelain enamel.

2. A resistance unit of the character described comprising a hollow core of porcelain, a porcelain vsaid wire and projecting through the slot in said sleeve, said core and resistance wire being cemented in said sleeve with porcelain enamel.

3. A resistance unit of the character described comprising a core of porcelain, a. porcelain sleeve having a narrow longitudinal slot, said sleeve enclosing said core; a resistance wire on said core, spaced terminal strips engaged with said wire and projecting through the slot in said sleeve, .said core and resistance wire cemerited, in said sleeve with no 1 .1 enamel, said core having a. plurality or openings extending lengthwise therethronsh.

4. A resistance unit of the character described speced terminal stripe engaged with comprising a hollow core of porcelain, a. porcelain sleeve having a narrow longitudinal slot, said sleeve enclosing said core, aresistance wire on said core, spaced terminal strips clamped around said wire and core and projecting through the slot in said sleeve, said core and resistance wire being lcemented in said sleeve with porcelain ename 5. A method of making resistance units which comprises wrapping a. resistance wire about a hollow porcelain core, clamping the wire in place by means of terminal strips, coating the wire and core with porcelain enamel and mounting them while wet with the enamel in a porcelain sleeve.

6. A resistance unit of the'charecter described comprising a flattened longitudinally split porcelain sleeve, a flattened longitudinally apertured porcelain core, a. resistance wire wound on said core and terminal strips clamped to the wire, said core and resistance wire being mounted in said sleeve and secured therein by porcelain enamel, and said strips projecting laterally through the slot in the sleeve.

JOSEPH J. CERNY.