US3323093A

US3323093A - Precision potentiometers

Info

Publication number: US3323093A
Application number: US380181A
Authority: US
Inventors: Gilbert J Orozco
Original assignee: Litton Industries Inc
Current assignee: Litton Industries Inc
Priority date: 1964-07-03
Filing date: 1964-07-03
Publication date: 1967-05-30
Anticipated expiration: 1984-05-30

Description

May 30, 1967 G- J. OROZCO PRECISION POTENTIOMETERS 2 Sheets-Sheet 1 Filed July 5, 1964 3 INVENTOR. Gilberf (I Orozao ATTORNEY May 30, 1967 G. J. OROZCO PRECISION POTENTIOMETERS 2 Sheets-Sheet 2 Filed July 5. 1964 INVENTOR. 6276px? J. Oraz c0 ATTORNEY United States PatentO 3,323,093 PRECISION POTENTIOMETERS Gilbert J. Orozco, New Rochelle, N.Y., assignor to Litton Industries, Inc., Beverly Hills, Calif. Filed July 3, 1964, Ser. No. 380,181 6 Claims. (Cl. 338-132) This invention relates to otentiometers, more particularly of the stacked type embodying two or more potentiometer resistor element assemblies in one housing conjointly controlled by a single input shaft.

The object of the invention in general terms is to improve the construction and reduce the size of multi element potentiometers in which a plurality of potentiometer units are ganged to form a unitary assembly for operation by a single input shaft.

In electrical apparatus employing a plurality of potentiometers for control purposes, it is frequently desirable to combine two or more potentiometers for simultaneous adjustment of the electrical functions of the potentiometers by a single control or input shaft. If the separate shafts of several potentiometers are coupled together by external mechanical coupling means, it is difficult to phase the separate units with the required precision and an error may be introduced as a result of play or backlash in the coupling. Even if the separate potentiometer units are bolted or secured together for adjustment by a single input shaft, the attachment and phasing of the separate units may present problems, such as undersirable bomplexity and cost. In any event such assemblies of the prior art are rather bulky, particularly where multi-turn potentiometers in which the input shaft is rotated through several revolutions are employed.

The present invention obviates these and other disadvantages of the prior art by a novel stacked resistor element assembly. In accordance with the invention, the potentiometer resistor element are mounted back-to-back in a single casing and a supporting member is provided which overlies the resistor units and carries all of the adjustable contact members or wipers.

An object of the invention therefore is to provide a compact construction which utilizes a novel rotatable contact carrier or support cooperating with a plurality of potenti0- meter resistor elements which may be of the multi-turn yp Another object of the invention is to provide a potentiometer having stable electrical and mechanical characteristics, and which comprises a plurality of resistor elements each embodying an insulating core or coil form on the outside surface of which is wound a multiturn, closely spaced resistance element.

A still further object of the invention is to support the contact members or wipers of a multi-element potentiometer in an improved manner.

Still another object of the invention is to provide improved means for dampening movement or vibration of the movable contact support and the movable contacts on said support in a multi-element or stacked compound potentiometer.

A feature of the invention is the utilization of a cupshaped contact or wiper support for a potentiometer and an annular dampening ring engaging the end surface of said support to dampen vibration thereof without imposing excessive frictional load on the rotating elements of the potentiometer.

. In accordance with the embodiment of theinvention to be described, a compound or multi-element potentiometer having a plurality of stacked resistor units is provided with a rotatable input shaft concentric with the insulating cores of the resistor units. Each of the resistor units includes a compact core or coil form having a multiturn resistance element wound on the outside of the coil form. In order to obtain adjustable electrical connections to the respec tive resistor units, a pivoted contact member or wiper is provided for'each of the resistor units, said pivoted contact members being mounted on or carried by an external rotor or supporting member which is attached to the input shaft. The rotor or supporting member is preferably hollow or cup-shaped and provided with slots in which the respective contact members or wipers are attached to the supporting member, the mounting of the contact members being adjustable in order to permit phasing of said members with respect to the associated resistor units. In order to avoid vibration or transverse movement of the cup-shaped support when the potentiometer is subjected to impact or shock in service, an annular ring of plastic or other suitable shock-absorbing material is mounted in a position to engage the edge of the cupshaped supporting member. In this manner a compact multi-element potentiometer is obtained which possesses stable electrical and mechanical characteristics and which is able to withstand external shock or vibration to which the poentiometer may be subjected.

The foregoing and other objects and advantages of the invention will be apparent from the following description of an illustrative embodiment thereof shown in the accompanying drawings, wherein FIG. 1 is a side elevation, partly in section, of a multielement potentiometer having four stacked multiturn elements;

FIGS. 2 and 3 are end and sectional views, respectively of the contact-supporting member or rotor shown in FIG. 1, FIG. 3 being a section taken on the line 33 of FIG. 2,-

FIG. 4 is a top view to an enlarged scale of one of the contact members or wipers, showing the adjustable mounting of the contact member or Wiper on the slotted supporting member; and

FIGS. 5 and 6 are sectional views to an enlarged scale of the contact member and the adjacent portion of the supporting member taken on the lines 5-5 and 6-6, respectively, of FIG. 4.

Referring to the drawings, there is shown in FIG. 1 an illustrative embodiment of the invention comprising a multi-element assembly 10 composed of four multi-turn resistor elements or

units

11, 12, 13 and 14 mounted backto-back to form a stack on a base or hub plate 16. An input or control shaft 17 is journaled in the base plate member 16 and is preferably of such length that it extends through the several resistor elements, as shown. The resist-or elements 11-14 are clamped to the base or hub 16 by a clamping ring 19 engaging the inner resistor unit 14. The clamping ring 19 is secured by screws or bolts 21 to the rear end of alongitudinal extension 22 of the base plate 16, said extension being for example in the form of a cylindrical sleeve integral with the base plate. Obviously the resistor elements may be secured in fixed position, after being located in the desired angular relation to the input saft, by any suitable clamping or equivalent means.

The resistor elements may be compact elements of conventional character but, as shown, are similar to the resistor elements disclosed in the patent of James W. Weidenman and Gilbert J. Orozco, Patent No. 3,187,286, dated June 1, 1965, the disclosure of which is incorporated herein by reference. Thus each resistor element 11-14 includes an insulating core member or coil form 24, preferably of ceramic material, on which a helical resistance element 25 is wound with the turns in closely spaced relation to minimize the depth or thickness of the unit. In the construction shown, a guide wire or filament 26 is wound on top of the resistance element in order to provide a guide for the contact member or wiper 27 as shown more clearly in FIG. 4, said guide element being of insulating material or consisting of an insulated wire. This feature is disclosed and claimed in the prior patent to 3 James W. Weidenman and David Rathje, No. 2,871,326 dated June 27, 1959. While other types of resistor elements may be employed in carrying out the invention, this construction has the advantage that the requirement for a separate mechanical feed for the adjustable contact member is obviated, thus permitting a reduction in the size and complexity of the potentiometer.

The contact members or wipers 27 engaging each of the resistor elements 11-14 are mounted on a supporting member or rotor 29 attached to the rear end of the input shaft 17 and having an extension or wall portion overlying the outside surface of the resistor elements. Thus the wipersupporting member or rotor preferably is substantially cup-shaped, with the base portion apertured to receive the input shaft to which it is clamped or fastened as by setscrews 31 and 32. In accordance with another feature of the invention, a dampening ring 33, of plastic or other suitable shock-absorbing material, is disposed in a recess in the base plate 16 opposite the open end of the cupshaped wiper-supporting member 29 and engaging the edge thereof to eliminate or minimize movement or vibration of the supporting member and of the contact wipers 27 when the potentiometer is subjected to external shock or impact in service. As shown, the dampening ring 33 may be provided with a thin projecting edge portion 34 bearing firmly against the inner surface of the rotor 29 over a small area, thus insuring effective dampening without imposing excessive frictional load on the input shaft.

The shaft 17 and rotor 29 attached thereto are supported for rotation in any suitable manner, as by

ballbearings

37 and 38. A conventional seal 39 may be provided Where necessary for the shaft 17 on the base plate 16. The potentiometer itself is enclosed in a dust-cover or case 41 secured to the plate 16 by screws 42. The terminal board 43 carries terminals 44 connected to the resistors elements 11-14 in the usual manner and through slip-rings 45 and cooperating brushes 46 to the terminals 47 (FIG. 4) of the respective wiper contacts carried by the supporting member or rotor 29. The potentiometer is also provided with stop means to limit the rotation of the input shaft 17. As shown, the stop means 51 is of the balland-groove type described and claimed in my prior patent, No. 3,121,210 dated Feb. 11, 1964, to which reference my be made for a detailed disclosure thereof.

As stated above, the resistor elements are shown as similar to those described in the above mentioned Patent No. 3,187,286 of James W. Weidenman et al., and include pivoted contact wipers 27 supported by the rotor 29. In accordance with another feature of the invention, as shown more clearly in FIGS. 36, the supporting member or rotor 29 is grooved as indicated at 54 to receive insulating mounting lugs 55 in alinement with each resistor element. A series of radial slots 56 are milled in the sleeve portion of the cup-shaped rotor 29 to provide. a space for the wiper contacts 27. Slots 57 are provided at one edge of the slots 56 to receive mounting screws 58 employed to secure the mounting lugs 55 to the rotor 29 and to permit desired phasing adjustment of the contact wipers during assembly (see FIG. 6).

If desired, more than one aperture 56 and mounting slot 57 may be provided for each contact wiper, four equally spaced apertures and slots around the periphery of the rotor 29 being shown in FIGS. 2 and 3. This construction permits the wiper to be located at any one of several angularly spaced positions around the periphery of the rotor; or more than one contact wiper may be employed for one or more of the resistor elements.

Any suitable type of adjustable contact or wiper may be used instead of that described in the patent referred to above. As illustrated in detail in FIGS. 46, the preferred construction includes a metallic bracket 61 which is pivotally supported by a jewel bearing 62 in the insulating block 55. A flexible lead 63 connects the contact member 27 to a conductor 64 connected to a terminal 44 and clamped in position by a clamp 65. It will be apparent that the form of the wiper-supporting member 29 and the ar rangement of a pivoted contact or wiper 27 thereon results in a compact construction of multi-element potentiometer without sacrificing efficiency and reliability.

While only a single embodiment of the invention had been described in detail for the purpose of explaining the underlying principles thereof, various modifications in the form and arrangement of the components illustrated will occur to those skilled in the art and may be made without departing from the scope of the invention.

What is claimed is:

1. A multi-element potentiometer comprising an insulating core,

a plurality of multiturn resistance elements on the surface of said core, a rotatable contact-supporting member journaled on the axis of said core and having an extension overlying the surface of said multiturn resistance elements, and

pivoted contact members mounted on the extension of said contact-supporting member, one contact member being disposed in alignment with each of said resistance elements, each of said contact members being independently adjustable circumferentially on said supporting member to alter the point of engagement of said contact member with the corresponding resistance element.

2. A multi-element potentiometer comprising a base member, two or more stacked resistor units on said base member, each consisting of an insulating core member and a resistance element on said core member,

"said resistor units being mounted with one resistor unit abutting against said base member and another inner resistor unit behind it to form a stack,

an input shaft journaled in said base member and having the inner end thereof extending through the stacked resistor units, said base member having an integral extension inside said core members of the resistor units,

a clamping ring mounted on said integral extension and engaging the core member of the inner resistor unit to clamp the resistor units to the base member,

a contact-supporting member attached to the inner end of said input shaft opposite said base member and extending over the outside surface of said resistor units, said supporting member being provided with a series of separated circumferential slots, each of said slots being in alignment with one of said resistor units,

contact members adjustably mounted one in each of said series of slots in the supporting member for phase-adjustable engagement with the respective re sistance elements to provide electrical connections to said elements which are simultaneously varied by the turning of the input shaft, and

terminal connections for said resistance elements and contact members.

3. A multi-element potentiometer comprising two or more resistor units, each consisting of an insulating core member and a resistance element on said core member,

a base member on which said resistor units are mounted one behind the other,

means for clamping said resistor units to said base member,

an input shaft journaled in said base member and extending through said resistor units,

a cup-shaped Contact-supporting member attached to the end of said input shaft,

a plurality of contact members on said cup-shaped contact-supporting member, each engaging one of said resistance elements,

means for adjustably securing said contact members on said supporting member to permit relative phase ad= justment of each contact member with respect to its associated resistance element, and

terminal connections for said resistance elements and said contact members.

4. A multi-element potentiometer comprising two or more resistor units, each consisting of an insulating core member and a multiturn resistance element on said core member,

a base member on Which said resistor units are mounted one behind the other, t

an input shaft journaled in said base member and extending through the resistor units,

a cup-shaped contact-supporting member attached to the end of said input shaft spaced from said base member, said cup-shaped member being provided with a wall portion surrounding said resistor units,

a plurality of contact members pivotally mounted on said cup-shaped contact-supporting member and engaging the respective resistance elements to provide electrical connections to said elements which are simultaneously adjusted by the turning of said input shaft,

means on said contact-supporting member for elfecting relative independent phase adjustment between each resistance element and its associated pivoted contact member, and

terminal connections for said resistance elements and said contact members.

5. A potentiometer comprising a base member,

a resistor unit,

a rotatable input shaft journaled in said base member and extending through said resistor unit,

a contact-supporting member attached to the end of said input shaft and consisting of a base portion and a substantially cylindrical wall portion surrounding said resistor unit and projecting from the base portion of said supporting member, a

a contact member pivotally mounted on the wall portion of said contact-supporting member and engaging said resistor unit, and

an annular plastic ring mounted in fixed relation to said base member and engaging the periphery of the Wall portion of said contact-supporting member for damping the resulting movement or vibration of said member when the potentiometer is subjected to shock or impact during use.

6. A multiple-element potentiometer comprising a plurality of resistor units, each consisting of an insulating core member and a multiturn resistance element on the outer surface of said core member,

a base member on which said resistor units are mounted one behind the other,

an input shaft journaled in said base member,

a cup-shaped contact-supporting member having a substantially cylindrical Wall portion surrounding said resistor units, said contact-supporting member being attached to said input shaft and having the wall portion thereof provided with a plurality of circumferential slots spaced in both axial and circumferential directions,

a plurality of contact members mounted on said contact-supporting member and engaging the respective resistor elements,

means for pivotally and adjustably mounting said contact members in the slots of said contact-supporting member, and

a plurality of terminals conductively connected to said resistance elements and said contact members, respectively.

References Cited UNITED STATES PATENTS 2,599,126 6/1952 Reed 336-440 X 2,657,295 10/1953 Barclay 33 8132 2,686,634 8/1954 Kolisch 338l30X 2,974,299 3/ 1961 Youngbeck 33 81 63 3,011,142 11/1961 Mair 338-132X 3,187,286 6/1965 Weidenman 338149 RICHARD M. WOOD, Primary Examiner.

I. G. SMITH, Assistant Examiner.

Claims

6. A MULTIPLE-ELEMENT POTENTIOMETER COMPRISING A PLURALITY OF RESISTOR UNITS, EACH CONSISTING OF AN INSULATING CORE MEMBER AND A MULTITURN RESISTANC ELEMENT ON THE OUTER SURFACE OF SAID CORE MEMBER, A BASE MEMBER ON WHICH SAID RESISTOR UNITS ARE MOUNTED ONE BEHIND THE OTHER, AN INPUT SHAFT JOURNALED IN SAID BASE MEMBER, A CUP-SHAPED CONTACT-SUPPORTING MEMBER HAVING A SUBSTANTIALLY CYLINDRICAL WALL PORTION SURROUNDING SAID RESISTOR UNITS, SAID CONTACT-SUPPORTING MEMBER BEING ATTACHED TO SAID INPUT SHAFT AND HAVING THE WALL PORTION THEREOF PROVIDED WITH A PLURALITY OF CIRCUMFERENTIAL SLOTS SPACED IN BOTH AXIAL AND CIRCUMFERENTIAL DIRECTIONS, A PLURALITY OF CONTACT MEMBERS MOUNTED ON SAID CONTACT-SUPPORTING MEMBER AND ENGAGING THE RESPECTIVE RESISTOR ELEMENTS, MEANS FOR PIVOTALLY AND ADJUSTABLY MOUNTING SAID CONTACT MEMBERS IN THE SLOTS OF SAID CONTACT-SUPPORTING MEMBER, AND A PLURALITY OF TERMINALS CONDUCTIVELY CONNECTED TO SAID RESISTANCE ELEMENTS AND SAID CONTACT MEMBERS, RESPECTIVELY.