US3863194A

US3863194A - Hermetically sealed adjustment for high voltage potentiometer

Info

Publication number: US3863194A
Application number: US419168A
Authority: US
Inventors: Jr Charles Edward Dorwart; Meade Goodman Bierly; Jr Charles Nelson Fendrich; John Thomas Roland
Original assignee: AMP Inc
Current assignee: TE Connectivity Corp
Priority date: 1973-11-26
Filing date: 1973-11-26
Publication date: 1975-01-28
Anticipated expiration: 1992-01-28

Abstract

The disclosure relates to a potentiometer for use in high voltage systems of the order of 8 kilovolts wherein the resistance of the potentiometer is adjustable externally of a can containing the potentiometer. The potentiometer is electrically insulated from the externally extending adjusting screw and is hermetically sealed within the can. The adjustment of potentiometer resistance is provided by connecting an adjusting screw which extends through a housing to a threaded rod which is secured to a metal bellows which is sealed in the internal housing within the can to hermetically seal the adjusting screw from the housing interior portion. The threaded rod is coupled via an insulating coupler or spacer to the slide rod of the potentiometer whereby axial movement of the threaded rod moves the slide rod and thereby controls the resistance of the potentiometer. The potentiometer is mounted in the housing and insulated therefrom by insulating spacers, the housing and can being filled with oil.

Description

United States Patent Dorwart, Jr. et al.

[ Jan. 28, 1975 l l HERMETICALLY SEALED ADJUSTMENT FOR HIGH VOLTAGE POTENTIOMETER [75] Inventors: Charles Edward Dorwart, ,lr.,

Columbia; Meade Goodman Bierly; Charles Nelson Fendrich, .lr., both of Elizabethtown; John Thomas Roland, Manhcim, all of Pa.

[73] Assignee: AMP Incorporated, Harrisburg, Pa.

[22] Filed: Nov. 26, 1973 [21] Appl. No.: 419,168

{52] U.S. (fl. 338/164 I51] Int. Cl. H0lc 5/02, F16j 15/50 {58] Field of Search 74/182; 338/164, 231

[56] References Cited UNITED STATES PATENTS 1,478,815 12/1923 Blauvclt H 74/182 X 3,187,289 6/l965 Rolwes 338/164 3,248,678 4/1966 Remus 338/164 3,373,395 3/1968 Sargent 338/164 I 3,441,894 4/1969 Yamamoto et al. 338/231 Primary Examiner-J. V. Truhe Assistant ExaminerKenneth Hairston Attorney, Agent, or Firm-Gerald K. Kita [57] ABSTRACT The disclosure relates to a potentiometer for use in high voltage systems of the order of 8 kilovolts wherein the resistance of the potentiometer is adjustable externally of a can containing the potentiometer. The potentiometer is electrically insulated from the externally extending adjusting screw and is hermetically sealed within the can. The adjustment of potentiometer resistance is provided by connecting an adjusting screw which extends through a housing to a threaded rod which is secured to a metal bellows which is sealed in the internal housing within the can to hermetically seal the adjusting screw from the housing interior portion. The threaded rod is coupled via an insulating coupler or spacer to the slide rod of the potentiometer whereby axial movement of the threaded rod moves the slide rod and thereby controls the resistance of the potentiometer. The potentiometer is mounted in the housing and insulated therefrom by insulating spacers, the housing and can being filled with oil.

8 Claims, 2 Drawing Figures Patented Jan. 28, 1975 HERMETICALLY SEALED ADJUSTMENT FOR HIGH VOLTAGE POTENTIOMETER This invention relates to a hermetically sealed high voltage potentiometer which is adjustable externally of the device and more particularly, to such a potentiometer wherein rotary motion external of the housing containing the potentiometer is converted to a linear motion and transmitted through a metal bellows and electrically insulating coupler to a linear position potentiometer.

High voltage potentiometers for use in the 8 kilovolt area have been known to the prior art. One such type of prior art potentiometer has been hermetically sealed within an oil filled can, adjustment of the potentiometer taking place only by breaking the hermetic seal. Another type of prior art potentiometer has been positioned externally of the can containing the high voltage terminals. However, it is still necessary to provide a high voltage interface connector to the potentiometer and, furthermore, since high voltage is applied across the potentiometer, the external positioning thereof presents a substantial safety hazard.

In accordance with the present invention, there is provided a potentiometer for use in high voltage systems of the order of 8 kilovolts wherein the resistance of the potentiometer is adjustable externally of a can containing the potentiometer. The potentiometer is electrically insulated from the externally extending adjustingscrew and is hermetically sealed within the can. The adjustment of potentiometer resistance is provided by connecting an adjusting screw which extends through a housing to a threaded rod which is secured to a metal bellows which is sealed in the internal housing within the can to hermetically seal the adjusting screw from the housing interior portion. The threaded rod is coupled via an insulating coupler or spacer to the slide rod of the potentiometer whereby axial movement of the threaded rod moves the slide rod and thereby controls the resistance of the potentiometer. The potentiometer is mounted in the housing and insulated therefrom by insulating spacers, the housing and can being filled with oil.

It is therefore an objectof this invention to provide a high voltage, potentiometer which is adjustable externally of a hermetically sealed housing without breaking the seal.

It is a further object of this invention to providea high voltage potentiometer wherein the resistance is adjusted by converting a rotary motion to a linear motion'transmitted through an electrically insulatingcoupling to a linear position potentiometer;

It is a, still further object of this invention toprovide a high ,voltage, potentiometer positioned within a hermetically sealed housing which is adjustable externally of the housing.

The above objects and still further objects of the invention will immediately become apparent to those skilled in the art after consideration of the following preferred embodiment thereof, .which is provided by way of example and not by way of limitation, wherein: FIG. 1 is a partially cut away view in elevation of the high voltage potentiometer in accordance with the present invention; and.

FIG. 2 is a cross sectional view of a portion of the potentiometer of FIG. 1.

Referring now to the Figures, there is shown the high voltage hermetically sealed potentiometer in accordance with the present invention. The potentiometer device includes an external metal can [of an electrically conductive material such as aluminum having a housing 3 therein of an electrically insulating material such as a glass epoxy. The can 1 and housing 3 have one common wall over which is positioned a metal plate 5 which is soldered to the can with solder 7. An adjustment screw 9 passes through a locking ring 11 which is positioned on the plate 5, the screw 9 passing through an aperture in the plate into the housing 3 and threadedly engaging a threaded rod 13 within the housing. A metal bellows 15 is soldered to the threaded rod with solder 17 and to the side wall of the housing around the screw 9 to hermetically seal the screw from the interior of the housing. The bellows 15 is preferably formed from brass. The threaded rod is secured within a spacer or coupler 19 which is formed from an electrically insulating material such as a'glass epoxy. The spacer 19 includes grooves 21 to provide a larger tracking distance for any discharge from the high voltage components. A slide rod 23 which is an externally extending part of the self-contained potentiometer 25 is secured in the spacer l9 and is movable along the axis of the potentiometer 25 to adjust the resistance value thereof. The potentiometer is electrically insulatingly mounted within the housing 3 by means of spacers 27 coupling the potentiometer to the housing wall. The

spacers 27 are preferably formed from a glass epoxy material. The housing 3 and can 1 are filled with oil in well known manner the housing 3 opening into the can 1 at its leftmost end as shown.

Terminals

31, 33 and 35 are the three standard potentiometer output terminals which would be coupled to an external device in standard circuit operation.

The potentiometer 25' is adjusted externally of the can 1 by rotating the screw 9 by means of rotating a screw driver in the slot 29. This rotation will cause the rod 13 to move axially due to threading thereof into or out of the screw 9. The hermetic seal is maintained during this'movement by expansion and contraction of the bellows 15. The coupler or spacer 19 moves with rod 13 and therefore causes the rod 23 to move in the same manner to provide an adjustment of the potentiometer It can be seen that the adjustment takes place with the screw 9'always electrically insulated from the potentiometer 25, this taking place without the necessity of breaking the hermetic seal.

Though the invention has been described with respect to a specific'preferred embodiment thereof, many variations and modifications will immediately become apparent to those skilled in the art. It is therefore the intention that the claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.

What is claimed is:

1. An externally adjustable hermetically sealed high voltage potentiometer system comprising,

an-electrically insulating hermetically sealed housing,

a potentiometer in the form of a self-contained unit mounted on an interior wall of the housing adjacent one end thereof,

a linearly movable member for varying the resistance of the potentiometer slidably supported on the potentiometer unit and projecting from the unit into the housing, rotatable means extending through the opposite end wall of the housing with its inner end terminating short of the linearly movable member, insulating coupling means secured to the linearly movable member and provided with means cooperating with the inner end of the rotatable means upon rotation thereof to move the linearly movable member, and expandable means surrounding said rotatable means and secured to the other end wall about the rotatable means and to the cooperating means hermetically sealing said rotatable means from the interior of the housing. 2. A potentiometer system as set forth in claim 1 wherein said housing is filled with oil and further including a metal can surrounding said housing.

3. A potentiometer system as set forth in claim 1 wherein the inner end of said rotatable means and the means cooperating therewith comprise interfitting wherein said expandable means comprises a bellows.

Claims

1. An externally adjustable hermetically sealed high voltage potentiometer systeM comprising, an electrically insulating hermetically sealed housing, a potentiometer in the form of a self-contained unit mounted on an interior wall of the housing adjacent one end thereof, a linearly movable member for varying the resistance of the potentiometer slidably supported on the potentiometer unit and projecting from the unit into the housing, rotatable means extending through the opposite end wall of the housing with its inner end terminating short of the linearly movable member, insulating coupling means secured to the linearly movable member and provided with means cooperating with the inner end of the rotatable means upon rotation thereof to move the linearly movable member, and expandable means surrounding said rotatable means and secured to the other end wall about the rotatable means and to the cooperating means hermetically sealing said rotatable means from the interior of the housing.

2. A potentiometer system as set forth in claim 1 wherein said housing is filled with oil and further including a metal can surrounding said housing.

3. A potentiometer system as set forth in claim 1 wherein the inner end of said rotatable means and the means cooperating therewith comprise interfitting screw threads.

4. A potentiometer system as set forth in claim 2, wherein the inner end of said rotatable means and the means cooperating therewith comprise interfitting screw threads.

5. A potentiometer system as set forth in claim 1 wherein said expandable means comprises a bellows.

6. A potentiometer system as set forth in claim 2 wherein said expandable means comprises a bellows.

7. A potentiometer system as set forth in claim 3 wherein said expandable means comprises a bellows.

8. A potentiometer system as set forth in claim 4 wherein said expandable means comprises a bellows.