US3497856A - Adjustable potentiometer - Google Patents

Description

Feb. 24, 1970 L, W, SCHEEL 3,497,856

I ADJUSTABLE POTENTIOMETER Filed Sept. 20. 1967 2, Sheets-Sheet 1 0a/5 M ScHffL 5 Feb. 24, 1910 L. w. SCHEEL 3,497,856

ADJUSTABLE POTENTIOMETER Filed Sept. 20. 1967 2 Sheets-Sheet 2 0a/5 k/. 56h/51. Mg. 5 5V United States Patent O M' 3,497,856 ADJUSTABLE POTENTIOMETER Louis W. Scheel, Columbus, Nebr., assignor to Dale Electronics Inc., Columbus, Nebr., a corporation of Nebraska Filed Sept. 20, 1967, Ser. No. 669,201 Int. Cl. H01c 5/02, 5/00 U.S. Cl. 338-162 5 Claims ABSTRACT F THE DISCLGSURE An adjustable trimmer potentiometer having a lgear in engagement with an adjusting leadscrew, the gear being operatively connected to a wiper arm assembly which slidably engages the resistance element. The gear includes peripheral teeth extending therefrom which engage the threads of the leadscrew whereby rotation of the leadscrew will rotate the gear and hence the Wiper. The gear and its teeth are somewhat liexible to permit the deection or ratcheting of the teeth over the threads of the leadscrew when the wiper arm assembly reaches the limits of its travel to prevent damage to the unit.

A problem encountered in the fabrication and use of trimmer potentiometers utilizing an adjusting leadscrew is the damage resulting from adjusting the unit beyond its lixed limits. Thus, when the wiper arms reaches the limits of its travel, the unit is damaged upon continued rotation of the leadscrew.

Therefore, a principal object of this invention is to provide an adjustable potentiometer that will not have its internal parts damaged by adjustment beyond`ts design capabilities.

A further object of this invention is to provide an adjustable potentiometer having a exible gear in engagement with the leadscrew, the gear adapted to ratchet over the threads of the leadscrew when the wiper arm assembly reaches the limits of its travel.

A further object of this invention is to provide an adjustable trimmer potentiometer which is easily fabricated.

A further object of this invention is to provide an adjustable potentiometer of the trimmer type which is easily assembled.

A further object of this invention is to provide an adjustable potentiometer having mean's for generating sufficient leadscrew torque so that the potentiometer will maintain its position of adjustment.

A further object of this invention is to provide an adjustable potentiometer that will have a long operating life.

A further object of this invention is to provide an adjustable potentiometer which is economical of manufacture, durable in use and refined in appearance.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, and combination of the various parts of the device, whereby the `objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings in Which:

FIG. 1 is a top perspective view of the potentiometer;

FIG. 2 is an enlarged sectional view of the potentiometer as seen along lines 2 2 of FIG. 1;

FIG. 3 is an exploded perspective view of the potentiometer;

FIG. 4 is a sectional View of the potentiometer as seen along line `4 4 of FIG. 2 with portions thereof cut away to more fully illustrate the invention; and

3,497,856 Patented Feb. 24, 1970 ICC FIG. 5 is a sectional view as seen along lines 5-5 of FIG. 2 with portions thereof cut away to more fully illustrate the invention.

The potentiometer of this invention is generally designated by the reference numeral 10 and includes an upper case 11 and a lower case 13 which are bonded together by any convenient means. Case 13 is provided with an upstanding shoulder 15 extending therearound inwardly of its periphery as best seen in FIG. 3. Case 13 is provided with a circular compartment 17 which extends around an upstanding post portion 19. Post portion 19 has a reduced diameter portion 21 at its upper end thereby defining a shoulder 23 therebetween. As seen in FIG. 3, post portion 19 is provided with a pair of cut away areas 25 and 27 on opposite sides thereof. Shoulder 15 has three notches 29, 31 and 33 formed therein which are adapted to receive leads 35, 37 and 39 respectively.

The numeral 41 generally designates a circular resistance coil which is comprised of a core 43 and windings 45. Coil 41 is mounted in the circular compartment 17 of lower case 13 by any suitable means. The opposite ends 47 and 49 of coil 41 terminate in spaced relationship within compartment 17 of lower case 13. Terminal connecting elements 51 and 53 are secured to the lower surfaces of the opposite end portions of coil 41 and the insulated leads 35 and 37 are connected to the elements 51 and 53 respectively.

A collector 55 is mounted on reduced diameter portion 21 and has a downwardly extending tab 57 received by cut away area 25. Collector 55 also has a downwardly extending tab 59 which is received by cut away area 27. Tab 59 includes a horizontal portion 61 which is secured to the under side of lead 37. The numeral 63 designates a tab which extends radially outwardly from collector 55 as best illustrated in FIG. 3. A wiper 65 is mounted on reduced diameter portion 21 above collector 55 and has a pair of upwardly extending tabs 67 and 69 provided thereon. As seen in FIG. 3, wiper is provided with a resistance coil engaging portion 71 which is arcuate in cross-section and which is designed to wipe upon the resistance coil 41. The other end of wiper 65 is provided with a downwardly extending tab 73 which is adapted to engage tab 63 to limit the travel of the wiper.

A drive coupler 75 is mounted on the upper portion of wiper 65 and rotatably embraces a portion of the reduced diameter portion 21 as seen in FIG. 2. Drive coupler 75 has a central opening 77 which embraces the reduced diameter portion 21 and has a pair of openings 79 and S1 extending vertically therethrough as best illustrated in FIG. 3'. As also illustrated in FIG. 3, drive coupler 75 is provided with three slots 83, 85 and 87 formed in its peripheral flange 89. The openings 79 and 81 in drive coupler 75 are adapted to receive the upwardly extending tabs 67 and 69 of wiper 65 so that wiper 65 will be rotated upon rotation being imparted to drive coupler 75.

Case 11 includes a downwardly extending central post portion 91 which is adapted to be positioned directly over reduced diameter portion 21 as illustrated in FIG. 2. The lower peripheral edge 93 of case 11 is adapted to be received on the upper end of case 13 as illustrated in FIG. 2 and would be secured thereto by any convenient bonding method. The numeral 95 designates a flexible gear having a central opening 97 through which post 91 extends. Gear 95 has three tabs 99, 101 and 103 extending downwardly therefrom which are received by slots 83, S5 and 97 respectively in drive coupler 75. Gear 95 has a plurality of peripheral teeth extending outwardly and downwardly therefrom as illustrated in FIGS. l2 and 3. Spring 107 is mounted on post 91 between gear 95 and the upper surface of drive coupler 75 as illustrated in FIG. 2.

A leadscrew 109 is rotatably mounted in case 11 in a manner best seen in FIG. 4. The leadscrew includes an inner end 111 which is journalled in a bore 113 formed in case 11 and a slotted outer end 115. An O-ring 117 embraces leadscrew 109 adjacent the outer surface of case member 11 to prevent foreign material from entering the interior of the unit. Leadscrew 109 is maintained within case 11 by a rolled or spiraled spring 119 which extends thereinto and which is received by an annular groove 121 in the leadscrew. Spring 119 is compressed as it is inserted into the potentiometer and thereby causes drag to be applied to the groove 121 of the leadscrew. This drag generates suicient leadscrew torque so that the potentiometer will maintain its position of adjustment. Leadscrew 109 is also provided with a threaded portion 123 including a plurality of threads 125. As seen in FIG. 4, the teeth 105 of gear 95 are in mesh with the threads v 125 on leadscrew 109.

In operation, the leadscrew 109 may be rotated to adjust the potentiometer by use of a conventional screw driver. The rotation of leadscrew 109 will cause gear 95 to be `rotated due to the engagement of teeth 105 with the threads 125. The rotation of gear 95 causes drive coupler 75 and wiper 65 to be rotated therewith due to the connection thereof as previously described. The wiper 65 is thereupon moved over the top surface of resistance coil 41 so that the resistance in the electrical circuit can be selectively varied in conventional fashion. When the wiper 65 has reached the limits of its travel with respect to the resistance coil 41, the continued rotation of leadscrew 109 will cause the ratcheting of the teeth 105 with respect to the threads 125. The `flexible characteristics and design of the gear is such that the teeth 105 will be deflected upwardly or ride over the threads upon the continued rotation of the leadscrew 109 to provide a ratcheting eifect. Thus, the internal components of the unit will not be damaged due to continued rotation of the leadscrew since the teeth 105 will ratchet which means that gear 95, drive coupler 75 and wiper 65 will not be rotated. It can be appreciated that the teeth 105 can be indefinitely ratcheted with respect to the leadscrew without causing damage to either of the leadscrew or gear 95. It should also Ibe understood that not only do teeth 105 deflect upwardly but a portion of the outer end of gear 95 adjacent thereto also is dellected slightly upwardly during the ratcheting phenomena. Thus, it can be seen that an adjustable potentiometer has been provided which will not have its parts damaged by adjust-ment beyond its `designed capabilities.

The -components of the unit are constructed of conventional materials while gear 95 is preferably constructed of #25 Berylco.

Thus, it can be seen that the device accomplishes at least all of its stated objectives.

Some changes may be made in the construction and arrangement of my adjustable potentiometer without departing from the real spirit and`purpose of my invention, and it is my intention to cover by my claims, any modified forms `of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim:

1. In an adjustable potentiometer,

a housing,

a compartment in said housing,

an arcuate resistance element in said housing,

an electrical collector means in said housing,

a movable wiper movably mounted on said collector means and being in movable electrical contact with said resistance element,

means on said housing limiting the movement of said wiper,

a circular gear means rotatably mounted in said housing and being operatively connected to said wiper whereby rotation of said gear means will cause said wiper to be moved on said resistance element,

an elongated leadscrew rotatably mounted in said housing and having a threaded portion normally in threaded engagement with said gear means whereby rotation of said leadscrew will normally cause the rotation of said gear means,

said gear means being resilient and being capable of being deliected out of engagement with said leadscrew when said leadscrew is continued to be r0- tated after said wiper reaches the limits of its travel,

said gear means being operatively connected to an insulated drive coupler which is operatively connected to said wiper,

said gear means including a plurality of tabs extending therefrom which are detachably received by said drive coupler, said wiper including a plurality of tabs extending therefrom which are detachably received by said drive coupler,

and a circular spring means positioned between said gear means and said drive coupler adapted to yieldably resist the movement of said gear means and drive coupler towards each other.

2. In an adjustable potentiometer,

a housing,

a compartment in said housing,

an arcuate resistance element in said housing,

an electrical collector means in said housing,

a movable wiper movably mounted on said collector means and being in movable electrical contact with said resistance element,

means on said housing limiting the movement of said wiper,

a circular gear means rotatably mounted in said housing and being operatively connected to said wiper whereby rotation of said gear means will cause said wiper to be moved on said resistance element,

an elongated leadscrew rotatably mounted in said housing and having a threaded portion normally in threaded engagement with said gear means whereby rotation of said leadscrew will normally cause the rotation of said gear means,

said gear means being flexible and having peripheral teeth extending outwardly therefrom which are adapted to engage the threads of the threaded portion of said leadscrew,

the exible characteristics of said gear means permitting said gear teeth to be deflected and ride over the threads of said leadscrew thereby providing a ratcheting effect when said leadscrew is `continued to be rotated after said wiper reaches the limits of its travel,

said gear means being of metal construction and being operatively connected to an insulated drive coupler which is operatively connected to said wiper,

said gear means including a plurality of tabs extending therefrom which are detachably received by said drive coupler, said wiper including a plurality of tabs extending therefrom which are detachably received by said drive coupler, said drive coupler being positioned between said gear means and said wiper.

3. In an adjustable potentiometer,

a housing,

a compartment in said housing,

an arcuate resistance element in said housing,

an electrical collector means in said housing,

a movable wiper movably mounted on said collector means and being in movable electrical contact with said resistance element,

means on said housing limiting the movement of said wiper,

a circular gear means rotatably mounted in said housing and being operatively connected to said wiper lwhereby rotation of said' gear means will cause said wiper to be moved on said resistance element,

an elongated leadscrew rotatably mounted in said housing and having a threaded portion normally in threaded engagement with said gear means whereby rotation of said leadscrew will normally cause the rotation of said -gear means,

said gear means being ilexible and having peripheral teeth extending outwardly therefrom which are adapted to engage the threads of the threaded portions of said leadscrew, y

the tlexible characteristics of said gear means permitting said -gear teeth to be deected and ride over the threads of said leadscrew thereby providing a ratcheting elect when said leadscrew is continued to be rotated after said wiper reaches the limits of its travel,

said housing being comprised of first and second case members detachably secured together, said resistance element, collector means and said wiper being mounted in said trst case member, said leadscrew and gear means being mounted in said second `case member.

4. In an adjustable potentiometer,

a housing,

a compartment in said housing,

an arcuate resistance element in said housing,

an electrical collector means in said housing,

a movable wiper movably mounted on said collector means and being in movable electrical contact with said resistance element,

means on said housing limiting the movement of said wiper,

a circular gear means rotatably mounted in said housing and being operatively connected to said wiper whereby rotation of said gear means will cause said wiper to be moved on said resistance element,

an elongated leadscrew rotatably mounted in said housing and having a threaded portion normally in threaded engagement with said gear means whereby rotation of said leadscrew will normally cause the rotation of said gear means,

said gear means being flexible and having peripheral teeth extending outwardly therefrom which are adapted to engage the threads of the threaded portions of said leadscrew,

the ilexible characteristics of said gear means permitting said 4gear teeth to be deflected and ride over the threads of said leadscrew thereby providing a ratcheting effect when said leadscrew is continued to be rotated after said wiper reaches the limits of its travel,

said gear means including a substantially flat central portion, said teeth extending outwardly and downwardly into engagement with the upper portion of the threads of said leadscrew, said teeth being deflected upwardly over said threads when said ratcheting eiect takes place.

5. The potentiometer of claim 4 wherein said leadscrew is maintained in said housing by a spring means frictionally engaging an annular groove formed therein r thereby creating torque on the leadscrew so that the leadscrew will maintain its position of adjustment.

References Cited UNITED STATES PATENTS 3,115,614 12/1963 Habeveder 338-174 3,124,778 3/1964 Youngbeck 338-131 X 3,242,452. 3/1966 Grunwald et al. 338-162, X 3,416,119 12/1968 Benthuysen et al. 3355-174 ROBERT K. SHAEFER, Primary Examiner H. l. HOHAUSER, Assistant Examiner U.S. Cl. X.R.

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