US2836689A

US2836689A - Variable resistance assembly

Info

Publication number: US2836689A
Application number: US534834A
Authority: US
Inventors: George J Mucher
Original assignee: Clarostat Manufacturing Co Inc
Current assignee: Clarostat Manufacturing Co Inc
Priority date: 1955-09-16
Filing date: 1955-09-16
Publication date: 1958-05-27
Anticipated expiration: 1975-05-27

Description

May 27, 1958 G. J. MUCHER VARIABLE RESISTANCE ASSEMBLY Filed Sept. 16, 1955 INVENTOR figg?? Jm'zef ATTORNEYS United States Patent O VARIABLE RESISTANCE ASSEMBLY George J. Mueller, Rochester, N. H., assignorto Clarostat Mfg. Co., Inc., Dover, N. H., a corporation of New York Application September 16, 1955, Serial No. 534,834

4 Claims. (Cl. 20L-48) This invention relates to a structurally and functionally improved electrical control embodying a detent structure which in its functionings will not interfere with or interrupt the electrical circuit within which the control is included.

As is well appreciated, in connection with controls of the variable resistance and potentiometer types, it is frequently desirable to incorporate a structure such that the operator-without visual inspection-will be instantly able to determine the relative positions of the control elements. Especially in installations for use by the Armed Forces, this determination should be capable of achievement by the sense of touch and despite the fact that the operator may be wearing gloves.

Therefore, it is a primary object of the invention to furnish an improved control in which the relative positions of the shiftable parts with respect to other portions of the assembly may be determined by feel and in which the operator will not interrupt or otherwise inter fete with an established circuit in properly determining this position.

Other. objects are those of providing a structure which will embrace a simple design and be capable of manufacture by quantity production methods at minimum expense, aside from the fact that the design will resultV in a mechanism capable of being operated through a great number of cycles without any failure occurring on the part of the control.

With these and other objects in mind, reference is had to the attached sheet of drawings illustrating one practical embodiment of the invention, and in which:

Fig. 1 is a rear view of a control;

Fig. 2 is a transverse sectional view taken along the line 2 2 in the direction of the arrows as indicated in Fig. l;

Fig. 3 is a view similar to Fig. 1, but showing the parts adjusted to a different position;

Fig. 4 is a transverse sectional view taken along the line 4--4 in the direction of the arrows as indicated in Fig. 3;

Fig. 5 is a face view of the control with the rotor removed; and

Fig. 6 is a perspective view of the contact element which forms a part of the control.

In these views, the numeral 10 indicates the body of the control, which, in accordance with conventional design, is preferably annular and formed of an insulating material. It mounts a resistance which may take the form of a strip of dielectric material around which closely spaced wire windings 11 are disposed; the resistance being set within an arcuate groove formedin body 10. As shown especially in Figs. 2 and 4, one edge of that resistance is thus exposed beyond the face of the casing or mounting body. The ends of the resistance are connected to terminals 12 conveniently projecting beyond the control and to which current-conducting leads (not shown) are connected.

The resistance is concentrically disposed with respect i assetati Patented May 27, 1958 ICS to and spaced from a contact ring 13. A terminal 14 may be integral with this ring and extend through a notch in body 10 at a point intermediate terminals 12. Terminal 14 is likewise connected to a current-conducting lead. Resilient bearing portions 15 extend inwardly from the ring and engage with the surface of a recess 16 formed in body 1G so as to maintain the ring in proper position.

With a View to providing a contact which bridges the gap between resistance 11 and ring 13 and traverses these elements, a rotor is furnished. As shown, this may include a substantially semi circular disc 17 of insulating material provided with a preferably noncircular opening through which the similarly contoured and reduced end 18 of shaft 19 projects. The latter is rotatably supported in bushing 20 atxed to body 10. Retaining

plates

21 and 22 may overlie and underlie the body 17 and be provided with openings through which the reduced end 13 of the shaft extends. The end of that shaft may be headed after the parts are secured to it so that the disc portion 17 will rotate with the shaft. The latter is prevented from moving in an axial direction outwardly by, for example, a plate 23 which is attached to the shaft and bears against the inner surface of bushing assembly 20. This plate may also act as a stop by engaging a projecting portion of body 10. Inward axial movement of the shaft with respect to the remaining control parts is conveniently prevented by a C-ring 24 riding within a groove formed in the shaft and bearing against the outer edge of the bushing 20.

Secured to the inner face of disc 17 by, for example,

rivets 2S is a mounting ring 26. This attachment may continue throughout an area of around lOO". A greater or lesser area of attachment may obviously be resorted to. In any event, a substantial portion of ring 26 (preferably in excess of extends beyond disc or plate 17 and conveniently includes bowed portions 27 between which a pair of outwardly extending parts 2S are provided. Between these, the material of the ring is reduced to furnish a bridging portion 29. The latter may be rounded in cross-section and extend in an inward direction so that the bridging portion acts as a fulcrum for a contact element. That Contact element has been illustrated to best advantage in Fig. 6.

l As therein shown, it may include a generally blockshaped body 29 formed of a copper graphite compound or any other suitable conducting material and having a length in excess of the distance between ring 13 and resistance 11. Its width should be such that it can be accommodated between the projecting portions 28 of the rotor ring 26. lt is formed in its underface with a transverse notch or recess 3@ of rounded configuration and corresponding in outline to the bridging portion 29. A transversely curved contact face 31 extending substantially parallel to axis of block 29, is included in the surface opposite that within which notch 3@ is formed. An inclined and similarly rounded contact face 32 forms a continuation of and merges into face 31. if desired, a shallow groove 33 may also be included in the block and adjacent to notch or recess 39. Thus, a member is furnished which, as shown especially in Figs. 2 and 3,

is resiliently supported by those parts 27 of ring 26` which extend beyond plate or disc 17. Therefore,

surfaces

31 and 32 of the block will ride in firm contact with ring 13 and resistance 11. Also, the block will be capable of rocking around the fulcrum provided by the bridging strip 29 while lateral movements of the block will be confined by the projecting portions 28. Obviously, therefore, with a turning of shaft 19, the block may be caused to traverse the entire operative area of the resistance strip 11 and to vary the eiectrical values established by the control of which it forms a part.

asesee Now, with a view to providing an operator-perceptible assembly which will enable the user to determine the position of the contact with respect to the resistance by feeL a detent structure is furnished. With a view to simplifying the present illustration, only a single detent has been shown. That detent has been illustrated as occupying a position adjacent one end of the resistance 11. It will be obvious that while in many respects this is a preferred structure, any suitable number of detents could be embodied and they might variously be positioned according to the needs of a given circuit. As illustrated, the detent will include an inwardly extending portion 34 preferably integral with ring 13. The surface of this extension will be bulged upwardly to furnish a rib 3S. of travel of the contact block 29. Therefore, in traversing this Zone of the ring, the block will pass over the rib 35.

Assuming therefore that the parts are assembled in the manner shown in Figs. l and 2, an operator may rotate shaft 19 to cause the contact to traverse the resistance and contact ring and thus vary the values within an electrical circuit. Any inequalities or unevenness of the parts will have no effect on this operation in that the block Z9 will simply fulcrum around the strip 29 as it rides over any uneven portions. At the same time, incident to the resiliency embodied in ring 2.6, especially adjacent the bridging strip 29, a firm and even electrical contact will prevail during this traversal. The same operation of the parts will occur when the contact passes over the detent provided by rib 35. In that case, surface 32 riding in contact with the ring 13 will simply cam over the rib. In such camming, it will rock around strip 29 as shown especially in Fig. 4. So moving, its surface 31 will remain in engagement with the resistance Accordingly, no interruption will occur to the electrical circuit which is involved. However, the operator will be entirely cognizant that the contact is traversing the detent structure in that he will feel the increased resistance to turning offered by the shaft 19 as the contact cams over the detent.

Thus, among others, the several objects of the invention as specifically aforenoted are achieved. Obviously numerous changes in construction and rearrangements of the parts might be resorted to without departing from the spirit of the invention as defined by the claims.

I claim:

l. ln a variable resistance assembly in combination rThat rib will extend within the path a body, a resistance element mounted by said body for traversal by a contact, a contact ring concentrically disposed with respect to said resistance and mounted by said body, a rotor movably connected to said body, a contact connected to said rotor and bridging said ring and said resistance for traversal thereof, means between said contact and contact ring providing, upon said rotor being turned, an operator-perceptible impediment to rotor movement and means forming part of the connection between said rotor and said contact whereby the latter remains in electrical association with said resistance over the entire operative length thereof.

2. In a variable resistance assembly as in claim l, said means between said contact and contact ring comprising a protrusion on said ring in the path to be traversed by said contact and said contact being rockingly mounted to oscillate as it engages said protrusion.

3. In a variable resistance assembly as in claim 1, said means forming part of the connection between said rotor and said contact including a fulcrum part rockingly engaging said contact for enabling said contact to remainv in electrical association with said resistance over the entire traversal. path thereof.

4. Ina variable resistance assembly in combination a body, a resistance element mounted by said body for traversal by a contact, a contact ring concentrically disposed with respect to said resistance and mounted by said body, said contact ring being provided with a surface for traversal by a contact and having a detent intersecting a zone of said surface, a rotor movably connected to said body, said rotor including a ring-shaped element being provided with a bridging strip, a contact formed with a notch for rockingly engaging said bridging strip, said contact bridging said ring and resistance for .simultaneous traversal thereof, whereby said detent imposes an operator-perceptible impediment to traversal of said ring and said resistance by said contact as said rocking engagement between said element and said contact retains said contact in electrical association with said resistance.

. References Cited in the le of this patent UNITED STATES PATENTS