US3629779A - Rectilinear potentiometer - Google Patents

Abstract

An inexpensive, variable resistance device such as a potentiometer is characterized by a minimum number of parts that include a housing and a cover that is secured thereto without the use of fasteners. The resistance element, the collector and terminal means may be integral with the cover. The wiper element is positioned on a brush block that is suitably mounted on a shaft that is located within the housing. A portion of the brush block extends through the housing for coupling to actuation means.

Description

United States Patent Inventors Arnold S. Louis llutlngs-on-Hudson, N.Y.;

Hans H. Worlnser, New Mlllord, NJ. 875.31 1

Nov. [0, 1969 Dec. 21, i971 Marklte Corporation New York, N.Y.

Appl. No. Filed Patented Assignee RECTILINEAR POTENTIOMETER 4 Claims, 8 DrawlngFigs u.s. c1 .Q 338/183, 338/184 Int. Cl. t .t ll0le 9/02 Field of Search 338/183,

176,177,178,179,l80,l81,182,197,l99,l84

[56] Relerenees Clted UNITED STATES PATENTS l,82l,927 9/l93l Caruso 338/178 2,706,230 ,4/l955 Bourns et al 338/I 83 X 2,873,337 2/1959 Bourns et al 338/l80 3,445,802 5/1969 Spaude 338/ l 80 X Primary Examiner-Thomas .I. Kozma Assistant Examiner-D. A. Tone Attorney-Leonard R. King ABSTRACT: An inexpensive, variable resistance device such as a potentiometer is characterized by aminimum number of parts that include a housing and a cover that is' secured thereto without the use of fasteners. The resistance element, the collector and terminal means maybe integral with the cover. The wiper element .is positioned on a brush block that is suitably mounted on a shaft that is located within the housing. A portion of the brush block extends through the housing for coupling to actuation means.

PATENTEDUECZI m 3.629.779

I N VE N TOR ARNOLD .5. L 01/16 B HANS H. WORMJER ATTORNEY RECTILINEAR POTENTIOMETER The aforementioned abstract is neither intended to define the invention of the application which, of course, is measured by the claims, nor is it intended to be limiting as to the scope of the inventicin in any way.

This invention generally relates to variable resistance devices and more particularly to an improved housing and cover construction for a potentiometer that is inexpensive and simple to manufacture.

There is presently a need for low-cost variable resistance devices such as potentiometers. The device must be compact and must be susceptible to utilization of the simplest form of manufacturing techniques in order to minimize cost.

In its broadest aspect the present invention provides a plastic housing which includes means for supporting a guide shaft. A slideable brush block is loosely mounted on the shaft and extends through the housing so that it may be coupled to actuation means. Conductive means and terminals well known in the art are formed on the cover member which, in the assembled condition, is placed over the open portion of the housing and sealed thereto by heat, solvent or adhesive sealing, or by upsetting at least a portion of the housing edge.

Accordingly, it is an object of this invention to provide an improved low-cost variable resistance device.

It is a particular object of this invention to provide a lowcost, side actuated rectilinear potentiometer.

It is another important object of this invention to provide a device as described above that is readily assembled.

It is a specific object of this invention to provide a low-cost side actuated rectilinear potentiometer as described above, in which cover fasteners are not required.

These and other features, objects and advantages of the invention will, in part, be pointedout with particularity and'will, in part, become obvious from the following more detailed description of the invention, taken in conjunction with the accompanying drawing, which forms an integral part thereof. In the various figures of the drawing like reference characters designate like parts.

FIG. I is a perspective view illustrating one embodiment of the present invention;

FIG. 2 is a transverse, cross-sectional view, in elevation, illustrating the housing comprising the present invention;

FIG. 3 is an enlargedplan view of the structure shown in FIG. 2;

FIG. 4 is a sectional elevational view taken along line 44 of FIG. 3;

FIG. 5 is a bottom view of the cover element comprising the present invention;

FIG. 6 is an end elevational view partially broken away and partially in section of the present invention; the view being taken along line 6-6 of FIG. 4;

'FIG. 7 is an exploded, perspective view illustrating a brush block and wiper assembly; and

FIG. 8 is a sectional elevational view similar to FIG. 4 with parts omitted for clarity, but illustrating an alternative embodiment.

Referring now to the drawing, there is shown in FIG. I a low-cost rectilinear potentiometer 10 comprising the present invention.

With particular reference to FIG. 2 the housing 12 of the potentiometer I0 will be discussed first prior to describing the novel features and assembly procedures of this invention. The housing 12, which is preferably a molded heat deformable plastic member, is comprised of sidewalls 14 and 16, a base wall 18 and end walls 20 and 22. The top of the housing 12 is open to define a cavity 24 therein and a ledge 25 is provided proximate the upper edge of the sidewalls I4 and 16. For purposes to be described in detail hereinafter the base wall 18 includes a longitudinal slot 26 having walls that converge in a downward direction. The convergence of the slot in the downward direction is not essential. It may converge in the opposite direction or be straight without affecting the essence of the design. The downward convergence shown is preferred as it permits broad tolerance in positioning of the shaft within the case and provides a single line of guidance for the brush block with maximum spacing from the shaft for stabilizing the brush block. The end walls 20 and 22 each include a slot that is T shaped in plan view, each of the T-shaped slots comprising a first recess 28 and a second recess 30. As shown in FIG. 2, the recesses 28' and 30 do not extend through the end walls. Recess 28 is inward of recess 30 and has an arcuate bottom portion 28a. By way of contrast, recess 30 has straight sidewalls and a flat bottom wall. Both of the recesses 28 and both of the recesses 30 are open at their upper extremities.

Turning now to FIGS. 3, 4, 5 and 6, there is shown the potentiometer 10 comprising the present invention. A shaft 34 is positioned within the cavity 24 in the housing 12 such that the ends of the shaft 34 rest on the arcuate bottom surface 28a of the U-shaped recess 28. A molded plastic, heat deformable brush block 36 is loosely'and slideably mounted on the shaft by means of lugs 38a and 38b. The bottom end extension 40 of the brush block 36 extends through theslot 26 formed in the base wall 18 and is provided with a notch 42 to permit coupling to an external actuating device (not shown). The tapered wall of the slot 26 minimizes frictional contact with the extension 40. Lug 38b is provided with a boss 44 which is arranged to receive a tail portion 46a of a metallic wiper member, 46. An opening 48 in the tail portion 46a is positioned over the boss 44 which is then heated by any suitable tool so as to be deformed and to thereby capture the wiper element 46.

With the shaft 34 in place, spacers 50 are inserted into each of the recesses 30 as to bear against the top ends of the shaft 34. A cover 52 is then inserted into the housing resting on the top surface of the spacers 50 and the ledges 25. It will be appreciated that the sidewalls l4 and I6 and the end walls 20 and 22 of the housing 12 extend above the top surface of the cover 52. The end walls may be rolled over such as shown by reference character 53 by any heated tool so as to deform the upper edges of the housing 12 and thereby define a lip portion for capturing thecover member 52. The spacers 50 in combination with wall portions of the recesses 28 and 30 minimize movement of the shaft 34.

In order to complete the potentiometer assembly suitable terminals 54, S6 and 58 are provided extending through the cover member 52 by suitable means such as eyelets 54a, 56a, and 58a. On the inside surface of the cover 52 there is formed, in a conventional manner, a conductive resistance element 60 and a conductive takeoff or collector member 62. The resistance element 60 and the takeoff member 62 are contacted by the brush 46 which is positioned above the upper surface of the brush block 36 and in opposition to the underside of the cover member 52. The formation of the resistance element 60 and the takeoff member 62 are conventional and do not form a part of the invention other than that their combination with the improved housing and assembly thereof provides an improved apparatus. The housing I2 is also provided with apertures 32a and 32b to permit mounting thereof. The end of the resistance element is connected through an eyelet 59a or other suitable means to the top surface of cover 52 wherein printed circuit means 61 connects eyelet 59a to terminal 54. This arrangement brings all terminals within the same area facilitating installation in a utilization apparatus. Thus the resistor element 60 appears across terminals 54 and 58 and the wiper terminal 56 has a direct electrical path to the wiper member 46.

In FIG. 8 there is shown an alternative embodiment of the present invention. In this construction the spacer members 50 described above are eliminated. The end wall 22' of the housingl 2 is provided with a blind hole 70 and the opposite wall 20 is provided with an aperture 72 that is coaxial with the blind hole 70. A shaft 74 is inserted through end wall 20' until it seats itself in the blind hole 70. The opposite end of the shaft 74 which could be splined is retained in aperture 72. The cover member 52' rests on a shoulder 76 formed on the interior of the housing I2 proximate the upper edges thereof. The

remainder of the construction is the same as described hereinabove with reference to the first embodiment.

From the foregoing it will be appreciated that an extremely low-cost potentiometer assembly has been provided which avoids the need for cover fasteners. The invention described hereinabove may very easily be assembled merely by dropping the components into place and by deforming the brush block and the housing, by means of heat, so as to provide a unitary assembly. Adhesives may be used as an alternative to the application of heat. The need for tapped holes or the like is eliminated and there is an attendant reduction in the number of parts that must be maintained in inventory. Assembly procedures are rapid, do not require highly skilled labor and yet provide a reliable device.

It is presently contemplated that the body member be formed of a heat deformable plastic by conventional molding techniques. However, thermosetting resins may be employed. Further, the body may be formed by extruding the central section from either a plastic or a metal, and employing suitable end caps. The body member may also be fabricated by employing conventional sheet metal techniques. If metal is employed for the body member, an insulating coating may be applied if application requirements so dictate.

Having thus disclosed the best embodiment of the present invention presently contemplated, it is to be understood that various changes and modifications may be made by those skilled in the art without departing from the spirit of the inventron.

What I claim as new and desire to secure by said Letters Patent is:

1. An improved, rectilinear potentiometer comprising:

a. an elongated housing including a lip portion on the periphery thereof extending entirely inwardly;

b. a shaft disposed in said housing;

c. means in said housing for supporting said shaft by the ends thereof;

d. brush block with wiper means slidably mounted on said shaft, a portion of said brush block extending through said housing and being adapted for coupling to an actuation device; and

e. a cover member including a resistance element, a collector and terminal means, said cover member being in nesting relationship with said housing and secured thereto by said inwardly extending lip portion.

2. The potentiometer in accordance with claim 1 wherein said means for supporting the ends of said shaft in said housing includes first recess means formed in opposite end walls of said housing, said recesses being open upwardly.

3. The potentiometer in accordance with claim 2 wherein there is further included spacer means intermediate the ends of said shaft and the interior, opposed surface of said cover member.

4. The potentiometer in accordance with claim 3 wherein there is further included second recess means in the end walls of said housing, said spacer means being positioned in said second recess means.

* l t t

Claims (4)

1. An improved, rectilinear potentiometer comprising: a. an elongated housing including a lip portion on the periphery thereof extending entirely inwardly; b. a shaft disposed in said housing; c. means in said housing for supporting said shaft by the ends thereof; d. brush block with wiper means slidably mounted on said shaft, a portion of said brush block extending through said housing and being adapted for coupling to an actuation device; and e. a cover member including a resistance element, a collector and terminal means, said cover member being in nesting relationship with said housing and secured thereto by said inwardly extending lip portion.

2. The potentiometer in accordance with claim 1 wherein said means for supporting the ends of said shaft in said housing includes first recess means formed in opposite end walls of said housing, saiD recesses being open upwardly.

3. The potentiometer in accordance with claim 2 wherein there is further included spacer means intermediate the ends of said shaft and the interior, opposed surface of said cover member.

4. The potentiometer in accordance with claim 3 wherein there is further included second recess means in the end walls of said housing, said spacer means being positioned in said second recess means.

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