US3657936A

US3657936A - Dimmer potentiometer switch

Info

Publication number: US3657936A
Application number: US31626A
Authority: US
Inventors: Edwin B Judd
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1970-04-24
Filing date: 1970-04-24
Publication date: 1972-04-25
Anticipated expiration: 1989-04-25

Abstract

An improved indexing mechanism for rotation of a cam bearing rotor through predetermined pattern of motions is provided to respond to a plunger actuation. The indexing and plunger motions are related by springs which act in tension and compression to advance the rotor in response to each push and return of the plunger.

Description

United States Patent Judd 1451 Apr. 25, 1972 154] DIMMER POTENTIOMETER SWITCH 2,997,840 8/1961 Rueger ..74/126 x 3,3 1,1 4 [72] Inventor: Edwin B. Judd, East Greenwich, RI. 8 O3 Duffield at al 200/156 [73] Assignee: General Electric Company y xam ner-Milton Kaufman Alto Paul E. R hf d, F nk L, N h d J h Apr. 24, Fgtgan 0C 01 ra EU auser an osep [21] Appl. N0.: 31,626

[57] ABSTRACT 52 U.S. c1 ..74 12s, 74/160, 74/162, An improved indexing mechanism for rotation of a am ar- 74 577 51-, 200 4, 200 53 1 200 15 ing rotor through predetermined pattern of motions is pro- 511' 1m.c1 ..-..Fl6h 27 02 vided to respond to a Plunger actuation The indexing and [58] Field Of Search ..74/88, 128,126, 144,160, p g motions are related y Springs WhiCh act in tension 74/162, 575, 576, 577 SF, 577 3; 200/156, 153 J, 4 and compression to advance the rotor in response to each push and return of the plunger. R f C! d [56] 8 e 6 Claims, 5 Drawing Figures UNITED STATES PATENTS 3,136,167 6/1964 Morner ..74/128 X I l DIMMER POTENTIOMETER SWITCH "The present invention relates to an indexing mechanism useful in obtaining controlled rotary motion responsive to actuation of a plunger under a push-push motion. Specifically, the present invention relates to a mechanism by which the contact arms of an electric switch are controlled by cams disposed on a rotary element and the movement of the rotary element is controlled by a plunger operating through a combination of spring elements on ratchet teeth also disposed on the rotary element.

A number of switch mechanisms having rotary elements bearing a combination of ratchet teeth and cams are known in the art. Such U.S. Pat. included Nos. 3,381,103; 3,045,501; 3,440,429; and doubtlessly others. All ofthese switches have mechanisms which rotate a rotary member by the co-operation. of a plunger element operating against the teeth of the ratchet portion of the rotary element and causing the selective rotation of the rotatable shaft in discreet essentially equal movements. 7

Also, these patents teach the control of the movement of electrical contact members by cams where the contact members'have the form of a leaf spring bearing an electrical contact on some portion thereof. Controlled movement is accomplished by the action of cam elements formed integrally with or mounted on the rotary member. These cams cause a movement of the contact onto or displacement of the contact away from a stationary contact.

In the construction and use of dimmers there is a preference that the size of a push-in actuator be relatively large so that, in addition to turning the switch on or off by the push-in motion, the level of power which the switch permits to pass to the controlled electrical load-maybe closely regulated by the turning of the-knob. For-this purpose the knob should be large enough so that the knob may be gripped comfortably by the fingers of the operator and a smooth rotarymotion may be imparted to the controlmechanism to set the lighting level orother power level at thedesired intensity. But becausethe knob is so large, there is a tendency to impart to it a force in switching the light on or off which is greater than that applied in many conventional switches which have actuators only large enough for use of a single finger. Considerable damage has dimmer switch mechanisms as a result of their by the user with the palm or heel of an open hand or by the side of a closed hand or arm or other larger force delivering implement. .When a dimmer knob is struckin this manner it must withstand an appreciably higher force and yet must operate the switch from the on to the off condition and must continue to function satisfactorily in the rotary control of the light intensity. Considerable damage has been done for examplc to twisted rod push-push cam mechanisms which are particularly susceptible to be damaged by too strong an actuating blow on the control knob.

It is accordingly one object of the present invention to provide an indexing mechanism which can resist damage due to being struck with a large force.

Another object is to provide an indexing mechanism which can withstand the motion imparted to the mechanism by a relatively high velocity impact.

Another object is to provide an indexing mechanism which permits smooth rotary control motion coupled with a damage resisting plunger motion.

A further object is to shallow silhouette.

Another object is to provide a mechanism for a switch having a combination of push-in and rotary activation.

Still another object is to provide a highly reliable switch mechanism having a combination of rotary and push-in actuation.

Other objects will be inpart apparent and in part pointed out in the description which follows.

In one of its broader aspect, the objects of the present invention are achieved by providing an indexing mechanism which comprises a rotatable member mounted for rotation in been done to being pounded provide a mechanism for a switch of a supporting frame, said member having ratchet teeth and cams spaced there around, a plunger having an at-rest position, spring means extending from said plunger and mounted to said frame to urge said plunger toward said at-rest position, wire spring means extending from said plunger to said rotatable member and biased against said rotatable member to engage the teeth of said ratchet, and said wire spring having a cross portion aligned with the ratchet teeth ratchet by pulling said ratchet through a distance related to the distance of movement of said plunger.

The manner in which the foregoing and other objects of the present invention may be achieved will be made additionally clear by reference to the accompanying drawings in which:

FIG. 1 is a perspective rear view of a mechanism such as is provided by the present invention shown within a housing which is partly broken away.

FIG. 2 is a more detailed view of such a mechanism with a greater portion of the housing removed and with the mechanism shown enlarged.

FIG. 3 is a cross-sectional view of such a mechanism show ing the relationship of the springs and rotary element.

FIG. 4 is a perspective view of selected parts of the mechanism essentially in the orientation shown in FIG. 2 but with elements removed for greater clarity of understanding.

FIG. 5 is a perspective view similar to that of FIG. 4 with the plunger mechanism advanced over the position illustrated in FIG. 4.

Referring now first to FIG. 1, an insulating housing 10 having end wall 12, side wall 14, and bottom wall 16 is shown in a perspective view with a portion of side wall 14 and bottom wall 16 broken away to expose a mechanism in the interior of the housing. The insulating closure of the housing is completed by an insulating spacer 18 which is mounted between the housing 10 and the metal mounting bracket 20 having the conventional size and conventionally located mounting screw holes 22 for mounting in a wall box in common use in the wiring device industry. A know 24 mounted at the end of a shaft extending from the housing provides the manual actuation of the mechanism by both rotary motions for lighting level control and by push-in motion for on-off control.

Turning now to F IG. 2, essentially the same parts are shown as those seen through the broken away portion of the housing of FIG. 1, but the housing is in this figure completely removed and the internal mechanism is shown enlarged as compared to the view seen in FIG. 1. In addition, only a portion of the insulating spacer l8 and of the metal mounting bracket 20 are shown to clarify the relationships of the various part. An insulating frame 30 is mounted to the bracket 20 by a pair of rivets 32, one of which is seen disposed in a channel 34 in the mounting leg 36 of the frame 30. Rivet heads 38 hold the 7 frame 30 to the mounting bracket 20 and against the insulating spacer l8.

Mounted within trunnion wells 40 at the right hand side of the frame are the trunnions 42 formed at the ends of the rotary member 44. The relationship of the rotary member and the trunnions 42 at the ends thereof may be seen with greater clarity in FIGS. 4 and 5 which is essentially an abbreviated view of portions of FIG. 2. The trunnions 42 are restrained within the wells 40 when the housing is in place on the mechanism by spring contacts 100 and/or 102. The trunnion bosses 46 which may be seen in place in FIGS. 1 and 3 keep the rotor 44 from leaving the trunnion wells 40 under severe jarring conditions. As best seen perhaps in FIG. 4, the rotary member 44 includes in addition to the end trunnions 42 apair of cammed

portions

48 and 50 and a centrally located ratchet portion 52. It will be noted that the cams of the cammed portion 48 are offset angularly from the cams of the cammed portion 50 in the specific mechanism illustratively shown. The cams of each portion are spaced at One set of cams is angularly offset from the other set by approximately 45. The ratchet teeth are spaced at about 45 rotor 44. Although the teeth may be angularly aligned with the to index said increments around the cams of the two cammed

portions

48 and 50, this is not necessary and their angular alignment may be independent of each other.

The alignment or absence of alignment of the ratchet teeth and cams is a function of such factors as length of ratchet spring, the positioning of the end stop of the plunger stroke, diameter of the rotor, and other factors.

Each ratchet tooth is seen to have one side which is aligned essentially radially from the axis of the rotor 44 and another side which is aligned approximately tangentially with the surface of the rotor. In one actual embodiment the radially aligned side of the ratchet tooth was undercut by about The ratchet spring 60 extends from a head portion or adapter 62 of plunger 66 where it is mounted as best seen in FIG. 3. In the embodiment shown the ratchet spring actually pivots on the shaft return spring 70. Also, in this particular arrangement the portion of the spring 60 extending from the adapter 62 has a generally U-shaped configuration and the bottom of the U is flat and aligned with the ratchet portion of the rotor 44. The flat bottom of the U slides over the tangentially oriented sides, of the ratchet teeth as the plunger returns to its at-rest position. As the plunger moves into the switch housing, the ratchet spring engages and pulls on the radially oriented sides of the ratchet teeth. Accordingly, it will be seen that as the plunger moves from the position shown in FIG. 4 to the advanced position shown in FIG. 5, a tension will be developed along the extending portion 60 of the ratchet spring and a pull will be exerted on the radially oriented face of the engaged ratchet tooth. This pulling imparts the rotary motion to the rotatable member 44 as the plunger head 62 is advanced into the housing as a result of a manual push on the rod portion of the plunger extending out from the mounting strap 20.

While the plunger is being pushed in there is also a deflection of the spring 60 relative to the shaft 66 as is seen by comparison of the alignment of spring 60 with the shaft 66 in FIGS. 4 as compared with that in 5. Accordingly, the bias spring pressure on the rotary member 44 is increased as the plunger is inserted or pushed further into the housing 10. The extent of movement of the plunger into the housing and accordingly the extent of the pull of the spring member 60 on the ratchet tooth may be limited by a stop such as the shoulder ring 80 which may be disposed at any location where the limiting ring will be brought into contact with an appropriate surface. The ring may be brought to bear against the outer surface of the mounting bracket for example as illustrated in FIG. 3.

As the plunger is pushed in and after the plunger has been advanced into the housing to its full extent, it will be urged into its initial at-rest position by the plunger return spring 70. Spring 70 has the general configuration of a letter W and the center portion of the spring 72 is the portion which bears against the adapter 62 of the plunger. This central portion may be, as is illustrated in FIG. 4, a straight portion lying in a slot 74 in the upper end of the adapter 62. The inner strands 76 I and 78 of the W" configuration as well as the

outer strands

77 and 79 of the W are bent upward from the shelf of the frame 30 toward the plunger end 62. The flat portions joining the inner and outer strands are also bent and are placed under torsional force so that there is a spring bias acting on the end of the plunger adapter 62 and tending to return it to its at-rest position. In this at-rest position, shoulder ring 80 may rests against the upper portion of a potentiometer housing 82 or it may rest as shown against a flat inner portion of frame 30.

An important and attractive feature in the return spring structure shown in FIGS. 4 and 5 is the smooth operation and smooth build up of return pressure on the plunger as it is inserted into the housing due in part to the folded configuration, or W configuration, of the wire spring which serves the plunger return spring function. The double fold of the spring members result in the application of a force directly down along the shaft of the plunger rather than a force to one side or another of the plunger. A force having a larger sideward component is generated for example if a leaf spring were used with 4 one end of the spring held in a fixed position and with the plunger acting on the other end. A sideward force is developed because as the plunger displaces the leaf spring to greater distance, the spring itself is bent through a' greater angle and its return force is accordingly also applied at a greater angle on the end of the plunger. The plunger has greater tendency to bind wherethe spring return force has a sideward component. This reverse bent spring 70 by contrast operates directly along the axis of the shaft and there is very even development of spring return force. The action of this spring return force on the shaftessentially along the axis there of is to return it smoothly to its at-rest position. There is no tendency of the shaft to bind due to the cumulative influence of a sideward force being applied to the shaft through the many many strokes which the shaft makes during its useful life.

It will be noted that in the embodiment shown, the ratchet spring 60 is linked at its held portion with the straight mid-portion of the shaft return spring 70. The end of the held portion of ratchet spring 60 is secured in place at the sides of adaptor 62 by the spring bosses 68. Because ratchet spring 60 operates through the mid-portion of return spring 70, there is a very extended useful life expectancy for this indexing mechanism and it has been found to go through many thousandths of cycles, over 200,000, without failure.

Returning now to FIG. 2 there are shown two sets of contacts including two fixed contacts and 92 which are mounted and held in frame 30 at a lower shelf 94 thereof, and two

movable contacts

96 and 98 mounted in

leaf spring members

100 and 102. The fixed ends of

leaf spring members

100 and 102 are at the left and are eyeletted by

eyelets

104 and 106 to the frame 30 so that suitable electrical connections can be made to the movable contacts by sodering wires to the eyelets. The free

movable ends

108 and 110 of the

strips

100 and 102 engage the sets of earns 48 and 50 of the rotor 44. Referring now first to the leaf spring 100 operating against the cam set 48, it will be seen that the end of the leaf spring 108 rests in the depression in the cam set and effectively prevents counter rotation of the rotatable member while the free end l10or the spring 102 rides up on a cam of the can set 50. As free end 110 rides up on a cam of the set 50, contact 92 is separated from contact 98 and opens an electrical path in an appropriate circuit associated with these contacts of the switch. As will be evident from the contours of the individual cams as seen best in FIGS. 4 and 5, the induced contact motion is a slow break and fast make most suitable for alternating current switching.

One of the features of this indexing mechanism is that it is adaptable for structures which provide both the rotary and push-push motion needed for dimmer type of operation. This adaptability is evident with reference to the FIGS. 4 and 5 and the function of the adaptor 62 seen in these figures. It will be evident that the shaft 66 is free to rotate within the adaptor 62 because the operation of the adaptor does not require it to go through any rotary motion. Also, the flat mid-portion of spring mechanism 72 effectively holds the adaptor aligned with these springs because of the location of the spring 72 within the .recess 74 at the end of the adaptor. The shaft 66 can accordingly be rotated about its axis in a receiving aperture at the end of the adaptor opposite spring slot 74 and can accordingly afford the rotary motion to the shaft both indepen' dently of the in and out motion of the shaft and adaptor and simultaneously with the in and out motion. With this independent rotary motion, the shaft 66 can operate on a potentiometer such as 82, shown in FIG. 3, to increase or decrease the resistance of an element of an associated dimmer circuit and accordingly control lighting of a lighting load associated with a control circuit which includes potentiometer 82. Such dimmer control circuits are well known in the art and described in the General Electric SCR Manual, 4th Edition. A potentiometer such as 82 performs the conventional control function in controlling the phase shift of a triggering circuit. Some flattened portion on the shaft, where it passes through the potentiometer, permits the rotary motion to be transmitted to a control element of the potentiometer tov effectively change the setting of the resistance element of the potentiometer.

' From FIG. 3 it is evident that the switch of the present invention provides a combination of rotary and plunger motions and is made up from a combination of components to provide this combined switching action within a structure of low silhouette. The frame 30 may have an overall depth for example of less than three quarters of an inch, and the overall mounting bracket and housing enclosure may have overall depth dimensions of less than one and one quarter inch.

The depth dimensions of the indexing and switching mechanism in the illustrative embodiment shown may be appreciably less than one half inch with the plunger push stroke of less than one quarter of an inch. In part, this shallow depth is achieved because the plunger adaptor and rotor are located side by side in the frameand the ratchet spring and return spring are extended from the plunger adaptor in the same general plane in which the plunger adaptor and rotor are disposed. The overall dimensions of the frame itself in which the several indexing and switching elements are mounted and contained are quite small being about one inch in width and less than one and one half inches in length. Because of these small width and length dimensions, auxilliary switching or dimming components can be provided in the end portions of an insulating housing such as in which the mechanism is mounted depending on the switching function to be performed. Such elements may include resistors, capacitors, solid state switches such as triacs or quadracs, audio frequency suppressing coils, and similar components as described in the art such as the General Electric SCR Manual, 4 th Edition.

It is evident that the mechanism of FIG. 3 is adaptable for use as a three-way switch mechanism due to the presence of two sets of

contacts

90 and 96 and 92 and 98 respectfully. When one of the stationary contacts is omitted, the switch becomes a single pole switch device. The second movable contact arm is included in either the single pole or three-way switches as it performs a function of preventing counter rotation of the rotor 44 Appropriate screw terminals may be provided for connec- 1 tion of electric power supply wires or wires may be brought through a port in the housing as at of FIG. 1.

What is claimed is:

1. An indexing mechanism which comprises a rotatable member mounted for rotation in a supporting frame, 7 1

said member having ratchet teeth spaced therearound,

a plunger having an at-rest position,

spring means mounted from said plunger to said frame and urging said plunger toward said at-rest position,

wire spring means extending from said plunger and biased against said rotatable member,

said wire spring means having a cross-portion aligned with the ratchet to index said ratchet by pulling said ratchet teeth as said plunger is pushed in,

said spring overriding the succeeding tooth on return of said plunger to its at-rest position.

2. The mechanism of claim 1 in which two sets of cams are located on said shaft, each set having a plurality of alternate elevations and depressions spaced around said rotatable member, and one set being angularly displaced relative to the other.

3. The mechanism of claim 2 in which leaf springs are mounted on said support frame to engage the cams and limit the counter rotation of the rotatable member.

4. An indexing mechanism which comprises a rotatable member mounted for rotation in a supporting frame, said member having ratchet teeth spaced therearound, a plunger having an at-rest position, spring means mounted from said plunger to said frame and urging said plungler toward said at-rest position,

said spring means avmg a W shape in which the outer ends are held in the support frame and the center fold acts on a plunger head,

said spring overriding the succeeding tooth on return of said plunger to said at-rest position.

5. An indexing mechanism which comprises a rotatable member mounted for rotation in a supporting frame,

said member having ratchet teeth spaced therearound,

a plunger having an at-rest position,

said plunger return spring means having a reverse bend between the portion where the wire is held in the support frame and the point where it acts on the plunger,

said wire spring having a cross-portion aligned with the ratchet to index said ratchet by pulling said ratchet teeth as said plunger is pushed in,

6. The mechanism of claim 1 in which the end of the plunger closest to said rotatable member is nested in a plunger head and is rotatable therein.

Claims

1. An indexing mechanism which comprises a rotatable member mounted for rotation in a supporting frame, said member having ratchet teeth spaced therearound, a plunger having an at-rest position, spring means mounted from said plunger to said frame and urging said plunger toward said at-rest position, wire spring means extending from said plunger and biased against said rotatable member, said wire spring means having a cross-portion aligned with the ratchet to index said ratchet by pulling said ratchet teeth as said plunger is pushed in, said spring overriding the succeeding tooth on return of said plunger to its at-rest position.

4. An indexing mechanism which comprises a rotatable member mounted for rotation in a supporting frame, said member having ratchet teeth spaced therearound, a plunger having an at-rest position, spring means mounted from said plunger to said frame and urging said plunger toward said at-rest position, said spring means having a ''''W'''' shape in which the outer ends are held in the support frame and the center fold acts on a plunger head, wire spring means extending from said plunger and biased against said rotatable member, said wire spring means having a cross-portion aligned with the ratchet to index said ratchet by pulling said ratchet teeth as said plunger is pushed in, said spring overriding the succeeding tooth on return of said plunger to said at-rest position.

5. An indexing mechanism which comprises a rotatable member mounted for rotation in a supporting frame, said member having ratchet teeth spaced therearound, a plunger having an at-rest position, spring means mounted from said plunger to said frame and urging said plunger toward said at-rest position, said plunger return spring means having a reverse bend between the portion where the wire is held in the support frame and the point where it acts on the plunger, wire spring means extending from said plunger and biased against said rotatable member, said wire spring having a cross-portion aligned with the ratchet to index said ratchet by pulling said ratchet teeth as said plunger is pushed in, said spring overriding the succeeding tooth on return of said plunger to its at-rest position.