US3018459A

US3018459A - Variable resistor

Info

Publication number: US3018459A
Application number: US34394A
Authority: US
Inventors: Wilbur T Hardison; Warren D Hulbert
Original assignee: Bourns Inc
Current assignee: Bourns Inc
Priority date: 1960-06-07
Filing date: 1960-06-07
Publication date: 1962-01-23
Anticipated expiration: 1979-01-23
Also published as: GB965697A

Description

Jan. 23, 1962 w. 'r. HARDISON ETAL 3,018,459

VARIABLE RESISTOR Filed June 7, 1960 l V/Lawe I HA [QB/501V,

WARREN 0 HUL BERT INVENTORS ing bracket 15,

atent VARIABLE RESISTOR Wilbur T. Hardison and Warren D. Hulbert, Riverside, Califi, assignors to Bourns, Inc., Riverside, Califi, a corporation of California Filed June 7, 1960, Ser. No. 34,394 Claims. (Cl. 338-180) The present invention relates to variable resistors, which term includes otentiometers.

The primary object of the present invention is to provide a variable resistor of the type wherein a movable contact is shifted lengthwise along a resistance element by means of a rotatable leadscrew, which variable resistor can be mounted on the back side of a panel with just a threaded stud projecting through a hole in the panel, and with means exposed at the front side of the panel for adjusting the leadscrew.

Another object of theinvention is to provide means for adapting a variable resistor of the type which is normally mounted on a pair of parallel rods extending through tubular rivets in the body, so that the said variable resistor can be mounted on the back side of a panel with a slotted adjustment head projecting through the panel to enable the variable resistor to be adjusted from the front side of the panel.

These and other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment thereof, reference being had to the accompanying drawings, wherein:

FIGURE 1 is a perspective view of a leadscrew-adjusted potentiometer embodying the principles of the invention;

FIGURE 2 is a top plan view of the same;

FIGURE 3 is a sectional view, taken at 3-3 in FIG- URE 2; and

FIGURE 4 is an enlarged fragmentary sectional view of the right hand end of the device as it is shown in FIGURE 3.

In the drawings, the reference numeral designates in its entirety a panel mount potentiometer of the leadscrewadjusted variety shown in Patent No. 2,777,926, to Marian E. Bourns. The potentiometer lo comprises an elongated rectangular body 11, which is embraced on three sides by a channel-shaped sheet metal cover 12. The cover 12 is secured to the body by two tubular rivets 13 which pass through the sides of the cover 12 and through the body 11 near respective ends thereof. The rivets 13 also pass through aligned holes in the sides 14 of a U-shaped mountand the said rivets are headed over to secure the bracket sides 14 to the potentiometer body.

The body 11 is preferably molded of, dielectric plastic material, and is formed with a central base portion 16 and upstanding end portions 17 and 18. Mounted side by side in parallel grooves in the base portion 16 are a resistance element 20 and a conductor strip (not shown). The ends of the resistance element 20 and the conductor strip are connected to respective ones of terminal wires 21 which pass through a hole 22 in the end 17 of the body.

Journa-led at its ends in the end portions 17 and 18, and

extending over the resistance element 20 and conductor strip, parallel thereto, is a leadscrew 23, one end of which projects through to the outside and is provided with a head 24 that is slotted diametrically at 25 to receive a screwdriver or the like for adjusting purposes. The leadscrew 23 is held against longitudinal movement by a pin 26 which is inserted through a transverse hole in the body and engages a circumferential groove 27 in the leadscrew. A slider 30 embraces the leadscrew 23 and is operatively engaged by the threads thereof so that the slider is moved longitudinally of the leadscrew when the latter is turned, The slider 30 is prevented from turning with the lead screw by means of two runners 31 (only one of which can be seen in FIGURE 3), that extend downwardly from the slider at opposite sides thereof and slidably engage the edges of the central portion 16. Mounted on the bottom of the slider is a sheet metal contact member 32, having two laterally spaced resilient fingers 33, only one of which can be seen in FIGURE 3. The two fingers 33 wipe on the resistance element 20 and on the conductor strip, to make electrical contact therewith.

Normally, the potentiometer 10 is mounted on a pair of parallel screws or rods (not shown) which are passed through the hollow rivets 13. However, there are situations where it is desirable to mount the potentiometer on the back side of an instrument panel, with only the slotted head of the leadscrew exposed on the front side of the panel for adjustment purposes. To enable the potentiometer 10 to be mounted in this manner on a panel P (FIGURE 3), the bracket 15 is provided with means extending through a hole 34, in the panel for securing the potentiometer thereto and for adjusting the leadscrew.

As mentioned earlier, the bracket 15 is U-shaped in configuration, with sides 14 extending along the sides of the potentiometer body and secured thereto by rivets 13. The bracket sides 14 are connected by a bight portion 38 which is arched upwardly so that the center line of the leadscrew is disposed approximately between the top and bottom edges of the bracket. The bight portion 38 is apertured at 37, and a stud 36 is insertedthrough the aperture from the inside of the bracket. The aperture 37 is non-round, and preferably flat on two opposite sides thereof; the stud 36 being correspondingly shaped so that it fits snugly within the aperture and is thus prevented from turning with respect to the bracket. The stud 36 is provided at one end with a radial flange 39 which bears against the inside of the bight portion 38, and is clamped thereby against the end of the potentiometer body 11. Formed within the stud is a central bore 40' of a diameter to receive the leadscrew head 24, and this bore is joined by an annular shoulder 41 with an extension bore 42 of somewhat smaller diameter, which extends through to the right-hand end of the stud. The outer end of the stud is threaded externally at 43 to receive a mounting nut 44.

Rotatably disposed within the bore 42 is a cylindrical adjustment head member 46 having a radial flange 47 at one end extending behind and seating against the shoulder 41. Projecting from the left-hand end of the member 46 is a diametrically extending tongue 48 which seats in the slot 25 of the leadscrew head 24. The member 46 is provided with a circumferential groove 50, in which is seated an O-ring 51 of elastomeric material. The O-ring 51 provides a slight amount of frictional drag on the member 46 and also seals the clearance between the member 46 and the stud to prevent the entrance of dirt or moisture. The outer end of the member 46 is slotted transversely at 52 to receive a screwdriver or other adjusting tool.

The potentiometer 10 is mounted on back side of the panel P by inserting the stud 36 through the hole 34, and then screwing a nut 44 on the threads 43. A look washer 53 is preferably interposed between the nut 44 and the panel P so as to prevent the nut from loosening. With the potentiometer thus mounted on the panel, adjustment of the leadscrew is effected by merely turning the head member 46 with a screwdriver, the leadscrew being turned with the member 46 by the tongue 48 which is seated in the slot 25.

The bracket 15 with the stud 38 and associated parts may be assembled with the potentiometer at the time of manufacture to make a panel mount type of instrument. Alternatively, the bracket 15 and stud 38 may be sold separately and later assembled to a standard potentiometer by merely removing the rivets 13, placing the bracket sides 14- over the sides of the potentiometer body, and securing the bracket to the body with new tubular rivets.

While we have shown and described in considerable detail what we believe to be the preferred form of our invention, it will be understood by those skilled in the art that various changes may be made in the shape and arrangement of the several parts without departing from the broad scope of the invention as defined in the appended claims.

We claim:

1. A variable resistor adapted for mounting on the back side of a panel with adjusting means projecting through an aperture in the panel to the front side thereof, comprising an elongate leadscrew-actuated potentiometer having an elongate body and having an adjusting leadscrew head projecting from one end of the body; a U-shaped mounting bracket having opposed elongate limbs attached to said body and a bight portion extend ing across the said one end of the body; an externally threaded stud secured to said bracket and projecting therefrom substantially coaxially with said leadscrew head, said stud having a central bore into which said leadscrew head projects; a member rotatably disposed within said bore and having a driving engagement at one end there of with said leadscrew head, said member having its other end exposed for engagement by an adjusting tool; and a mounting nut cooperating with the thread of said stud.

2. For mounting an elongate leadscrew-adjusted variable resistor on the back side of a panel with adjusting means thereof projecting through an aperture in the panel to the front side thereof, said variable resistor having a longitudinally extending leadscrew and an elongate body of rectangular configuration with at least one fastening member extending transversely through said body from one side thereof to the other, said leadscrew including a head projecting from one end of said body, mounting means comprising: a mounting bracket, said mounting bracket being of U-shape and including elongate side portions extending longitudinally along opposite sides of said body and each side portion having an aperture therein through which said fastening member passes, an apertured bight portion interconnecting said side portions, and an externally threaded stud secured to said bight portion and projecting outwardly therefrom coaxial with said head, said stud having a central bore into which said leadscrew head projects; a member rotatably disposed Within said bore and having a driving engagement at one end thereof with said head, said member being retained within said stud and having its other end exposed for engagement by an adjusting tool; and a mounting nut screwed onto the threads of said stud.

3. For mounting an elongate leadscrew-adjusted variable resistor on the back side of a panel with adjusting means thereof projecting through an aperture in the panel to the front side thereof, said variable resistor having a longitudinally extending leadscrew and an elongate body of rectangular configuration, with at least one fastening member extending transversely through said body from one side thereof to the other, said leadscrew including a head projecting from one end of said body, mounting means comprising: a mounting bracket, said mounting bracket being of elongate U-shape and including: opposed elongate side portions extending longitudinally along opposite sides of said body and each side portion having an aperture therein through which said fastening member passes, an apertured bight portion intercon'necting said side portions and with the aperture in the bight arranged concentric with said head; an externally threaded stud inserted through the aperture in said bight portion, said stud having a radial flange arranged to be clamped against said one end of said body by said bracket, and said stud having a central bore into which said head projects; a member rotatably disposed within said bore and having a driving engagement at one end thereof with said head, said member being retained within said stud and having its other end exposed for engagement by an adjusting tool; and a mounting nut screwed onto the threads of said stud.

4. Potentiometric means adapted for alternative mounting according to either of differing modes, said means comprising: a leadscrew-actuated potentiometer comprising an elongate transversely perforate body and a leadscrew mounted therein and having an end accessible for actuation at one end of said body and said leadscrew being at said one end provided with a driver-slot; a U- shaped mounting bracket comprising opposed elongate limbs interconnected by an apertured bight portion, said limbs being disposed alongside said elongate body and being secured thereto; a flanged tubular stud having a tubular portion and a flange disposed and maintained between the body 'of said potentiometer and the bight portion of said bracket and there held captive by said bracket with the tubular portion of said stud extending through the aperture in the bight of the bracket; rotatable leadscrew-engaging driver means disposed in said tubular portion and constructed and arranged to engage said driver slot and rotate the leadscrew incident to being rotated, said driver means having in turn a driver slot; and means for securing said tubular stud to a panel.

5. Potentiometric means, comprising, in combination:

first means, including an elongate leadscrew-adjusted potentiometer of the type having an elongate body having transversely extending mounting means and an elongate adjusting leadscrew disposed longitudinally of said body, said leadscrew having a driving end exposed at one end of said body;

second means, including a threaded tubular stud and cooperating means threaded on the stud for securing the stud to a panel; and

third means, comprising interconnecting means closely embracing said tubular stud and said elongate body, said interconnecting latter means being constructed and arranged to maintain the said stud and the said body in fixed relationship each to the other and with the axis of the said tubular stud substantially in alignment with the axis of the said leadscrew with the driving end of said leadscrew facing the bore of said tubular stud.

References Cited in the file of this patent UNITED STATES PATENTS 2,358,991 Miller Sept. 26, 1944 2,371,159 Erb Mar. 13, 1945 2,458,314 Straub et al. Jan. 4, 1949 2,776,356 Kling Jan. 1, 1957 2,777,924 Youngbeck Jan. 15, 1957 2,777,926 Bourns Jan. 15, 1957 2,836,690 Barr May 27, 1958