US2433911A

US2433911A - Lead through terminal

Info

Publication number: US2433911A
Application number: US565617A
Authority: US
Inventors: Johnston Leith
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-11-29
Filing date: 1944-11-29
Publication date: 1948-01-06
Anticipated expiration: 1965-01-06

Description

Jan- 6 1943 l.. JOHNSTON LEAD THROUGH TERMINAL Filed Nov. 29, 1944 fllll :In n 1| Patented Jan. 6, 1948 UNITED STATES PATENT oEFlcE LEAD THROUGH TERMINAL Leith Johnston, Park Ridge, Ill.

Application November 29, 1944, Serial No. 565,617

The present invention relates to lead through terminals for establishing an electrical connection to an electrical device through a metallic housing. Terminals of this character have to be passed through the metal housing in such a way as to make a sealed joint with the housing.

'It is the purpose of my invention to provide a lead through terminal by utilizing a metallic eyelet which can be sealed to the housing in combination with a rubber sleeve under compression and a terminal rod for the rubber sleeve. It is a further purpose of my invention to provide a novel method of securing a lead through terminal connection in permanent sealed relation to the housing of an electrical device such as a transformer or condenser.

The Vnature and advantages of my invention will appear more fully from the following description and the accompanying drawing wherein a preferred form of the invention is shown. It should be understood, however, that the drawing and description are illustrative only and should not be taken as limiting the invention except irlsofa-r as it is limited by the claim.

In the drawing:

Figure 1 is a view in side elevation of arubber sleeve employed in the making of the lead through terminal;

Figure 2 is a longitudinal sectional view through a metallic eyelet which forms a part of the terminal;

Figure 3 is a sectional view taken longitudinally through the eyelet and showing the rubber sleeve compressed therein;

Figure 4 is a view in side elevation oi a terminal rod before it is combined with the assembly of Figure 3;

Figure 5 is a longitudinal sectional view through the terminal showing the assembly of the terminal rod with the rubber sleeve and the metallic eyelet;

Figure 6 is a fragmentary sectional view 1 Claim. (Cl. 174-153) 2 container in which the electrical device is housed. Many such devices require a hermetically sealed housing. The present lead through terminal is constructed to prevent air passage where the electrical lead comes through the housing.

Referring now to Figures 1 to 6 inclusive, a

'I preferred method of making the terminal and mounting it in a housing will be described. I show in Figure 1 a sleeve 10 which is constructed of a resilient compressible insulating material. The sleeve Ill desirably may be constructed of natural rubber or any of the known synthetic rubbers. One of the synthetic rubbers, neoprene, has been found particularly advantageous because of its cold flow characteristics. Some of the other synthetic rubbers also have a much greater resistance to deterioration by oil products than natural rubber, so for certain purposes they are to be, preferred. The sleeve I0 need not be limited to rubber as there are other resilient materials such as cork that may be used. The sleeve I0 has a relatively small bore I I.

In Figure 2, I show a metal eyelet I2 which may be slightly taperedv between its ends. As shown there is just enough taper for the punch used in drawing the eyelet from a blank. This eyelet has a flange I3 at one end for mounting upon a housing. The other end I4 is plain. The eyelet meets the flange with a flared portion to facilitate entry of the sleeve Il) into the eyelet. In carrying out my invention, the rst step is to assemble the sleeve i0 in the eyelet I2 to produce the combination shown in Figure 3. This assembly can be readily accomplished and it results in a slightk compression of the sleeve in the eyelet I2. The numeral I5 indicates the restriction of the bore II due to the compression of the sleeve I0 in the eyelet.

through a portion'of a housing showing the lead Figure 8 is a view similar to Figure 7 showing a i further modification; and

Figure 9 is a view similar to Figure 'I of a third modiiication of the terminal construction.

The lead through terminalof the present invention is adapted to be used in connection with electrical devices such as transformers', condensers', switches and` the like to establish a seal A terminal rod I6 is next forced through the sleeve I D. In operation it is desirable to use a lubricant of some type to aid the passage of the rod. This lubricant may be a material that will act as a cement between the rod and the sleeve IU after it has served its purpose as a means of reducing friction due to pressing the rod through the sleeve. The rod I6 will be noted as much larger in diameter than the bore II of the sleeve so that it expands the rubber sleeve I0. The expansion, however, cannot take place within the eyelet andthe forcing of the terminal rod through the eyelet puts the sleeve within the eyelet under compression radially of the eyelet and under tension axially of the eyelet. The tension is effective to hold the end portions of the sleeve against around the electrical leads that pass through a the ends of the eyelet. The portions Illa and Illb of the sleeve I are expanded outward until they overlap the ends ot the eyelet I2. An eective sealing is thus accomplished so that no air can pass through the eyelet I2,

. The next steps in the assembly are to form the ends of the rod I8 so that they may be used for attaching conductors. Figure 6 shows the rod ends as flattened and apertured to form eyelets Il and I8. Figure 6 also illustrates the manner in which-the terminal assembly is secured in a housing. The housing is indicated at I9. It is provided with an aperture which is large enough to receive the portion I0b of the sleeve l0. According to the preferred practice, I also provide a depression being of such size as to seat the flange I3 of the eyelet I2. The eyelet I2 is,

soldered to the housing I9 by flowing solder 2Ia around the ilange I3 in suilicient quantitiesto make a good seal.

Figure 7 of the drawing illustrates a slightly varied form of the invention. The variation consists in the following features. An eyelet 22 is utilized. This'eyelet may be slightly tapered in diameter as shown, or straight. It is also provided with a flange 24 which may be mounted like the flange I3 to the housing or placed against the inner surface of the housing as illustrated in Figure '7. The eyelet 22 extends through an opening 23 in the housing and has its upper end 25 flared outward slightly to facilitate forcing the sleeve Ill therein. In this form oi' the invention a different type of terminal rod 26 is shown. This terminal rod had a cylindrical portion which can be forced into the sleeve I0 to cause the sleeve to expand. The terminalv rod 26 has a threaded'terminal portion 21 and a. hexagonal portion 28 adjacent to the portion 21 to serve as a means for holding the rod when a wire terminal nut is threaded on the Portion 21 and to form one end abutment for the sleeve I0. After the terminal rod 26 is forced through the sleeve I0 and the eyelet 22, a washer 29 is placed thereon and the sleeve is compressed endwise between the

parts

28 and 29. The rod 2l is upset as indicated at 30 so as to hold the sleeve I0 under compression. The end of the rod 26 can be flattened as shown at 3| and apertured in the same operation that upsets the portions 30.

In soldering eyelets I2 and 22 to the housing I9, there is an additional advantage obtained toward sealing the device. The temperature of the solder used is in the neighborhood of 500 F. The rubber vulcanizes at somewhat above 300 F. There is enough heat loss between the solder and the rubber sleeve I0 to prevent over-heating of the rubber, but at the same time,thel heat conduction through the eyelet I2 causes the vulcanization and sticking of the rubber to the eyelet I2 and to a certain extent to the terminal rod I6. Therefore, in the final assembly an excellent seal is obtained.

The device shown in Figure 8 is essentially similar to that shown in Figures 1 to 6, except that a new terminal rod 32 is used. 'Ihe manner of mounting the terminal rod 32 in the sleeve I0 and the eyelet I2 is the same as the manner of completing the device shown in Figures 1 to 6. The terminal rod l2 is made with reduced end portions 32a and 32h that are smaller than the bore ofthe sleeve I0 so they can be bent and may have considerable freedom of movement with respect to the sealed part in the eyelet I2.

Figure 9 illustrates a type of tubular terminal rod assembled in the same fashion as the terminal rod I6 was membled with a sleeve Il and an eyelet I2. In Figure 9 the terminal rod 33 is hollow and has both ends flanged over as shown at 3l and 36, to mount an angular terminal strip 3l, and a washer 31. The sleeve Il) is compressed between the members 35 and 31 so as to make it bulge out over the ends of the eyelet I2. In this form of device the wiring 38 is led out through the rod 33 and wrapped around the strips 35. The wire is sealed in place by use of solder indicated at 39 which will also run into the hollow terminal rod 33 and seal it. If there is any doubt about the solder 39 sealing the hollow rod 33, the interior of the rod may be illled with a sealing composition after the lead 38 is drawn through and before the soldering is done.

It is believed that the foregoing description and the accompanying drawing will enable those skilled in this art to utilize the invention shown and described.

Having thus described my invention, I claim:

A method of prOducing a hermetlcally sealed lead through terminal which comprises forcing a sleeve of rubber through a metal eyelet, then forcing a, conductor rod much larger in cross section than the bore of the sleeve, through the assembled sleeve and eyelet, then soldering said eyelet to a supporting metal wall and thereby vulcanizing the rubber to the eyelet.

LEITH JOHNSTON.

REFERENCES CITED The following references are of record in the Number Name Date 1,852,454 Foster Apr. 5, 1932 1,899,591 Segar Feb. 28, 1933 2,014,004 Mershon Sept. 10, 1935 2,052,700 De Lange Sept. 1, 1936 2,138,660 Mann Nov. 29, 1938 2,167,286 Theobald July 25, 1939 2,169,967 Smith Aug. 15, 1939 2,170,718 Humphries Aug. 22, 1939 2,181,860 Adkinson Dec. 5, 1939 2,219,940 Ritz-Woller Oct. 29, 1940 2,223,153 Seifer NOV. 26, 1940 2,266,523 Waterman Dec. 16, 1941 2,368,548 Kalstein Jan. 30, 1945 2,387,630 Weakley Oct. 23, 1945