US2853567A - Switch mechanism - Google Patents

Description

Sept. 23, 1958 P. o. KOCK' 2,853,567

SWITCH MECHANISM Filed March 4, 1955 Fig.l.,

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' Zone 3 INVENTOR Paul O. Kock 344W am/r 22/ United States Patent 0 SWITCH MEESHANISM Paul (J, Koch, Columbus, .Ohio, .assignor to Bituminous 1 Coal Research, Inc, Bittsburgh, P a., a corporation of Delaware Application March 4, 1955, Serial No. 492,256 19 Claims. (Cl,- 200*31) This invention relates to a new switch mechanism which is automatically variable in response to a control signal. More particnlarly, this invention pertains to a new switch device having elements therein relatively movable in response to such a signal, and to a cam factor, for corresponding variation in cycle operation, or interval duration of switch action, or both as the signaling system may requ re.

A number of switch mechanisms embodying a timing factor have been utilized from time to time of varying degrees of complexity and cost. Certain of such devices employ a manually set indexing arm in clutching connection with-a timer arm such that upon energization of the timer, the-timing arm will move to a contact position reaching such when the interval indicated by the index arm has elapsed. In such a switch mechanism, the action interval is thus fixed in accordance with whatever the setting of the index arm may be. in other types of switch mechanism in a variety of applications, switch energization is provided for by means of cams. In many of these latter practices, the time interval of energization and the number of such intervals per cycle of the switch mechanism is substantially fixed in accordance with a cam of relatively fixed characteristic and position. Even in the case of adjustable cams, such an adjustment has beena prerequisite if a change in the length of camming interval is desired. In a number of various prior switch mechanism devices, further, the mechanism has not been reversible and in other cases, special resetting structure.

has been required. Such settings and adjustments, moreover, impede or prevent, particularly where manual in nature, the utilization of such switch mechanism in connection with operations for various industrial or other applications requiring quick changes for response to what ever the demand might be at the time in question. Still further, various of such prior switch mechanisms used for timing intervals and the like have tended to become quite complicated and therefore expensive in nature without that ruggedness and freedom from difficulty often re quired particularly near industrial operations associated with a considerable amount of dust and dirt.

In my invention, the foregoing difficulties and deficiencies have been overcome. A switch mechanism made in assassr movement between the switch and cam will cause a responsive change in cycle, or in duration of response, or in both. Moreover, such a variation in duration of switch response is flexible within a wide range and may be practically instantaneous if and as required. Again, the mechanism of this invention is automatically responsive to such a signal impressed on my new mechanism and without regard to whether the signal is reversible or of a oneway nature.

Other objects and advantages of this invention will be apparent from the following description and from the accompanying drawings, which are illustrative of one em bodiment only, in which:

Figure 1 is a view in front elevation of one embodiment of my invention which may be utilized in a number of industrial or other services;

Figure 2 is a View in elevation looking at the left end of the apparatus as viewed in Figure 1;

Figure 3 is a detail view of the path of movement of the switch pin relative to the switch;

Figure 4 is a schematic view of part of the apparatus shown in Figures 1 and 2 illustrating a no action effect situation in the switch mechanism condition;

Figure 5 is a schematic view of part of the apparatus shown in Figures 1 and 2 illustrating an action effect condition of the switch mechanism at less than the maximum number of cycles per unit of time and with interval duration variation;

Figure 6 is a schematic view of part of the apparatus shown in Figures 1 and 2 illustrating an action efiect condition of the switch mechanism with the maximum number of cycles per unit of time for the embodiment illustrated and with interval duration'variation;

Figure 7 is a schematic showing of zones of possible movement of a lever member shown in the illustrated embodiment of Figures 1 and 2 capable of yielding different "switch mechanism conditions with interval duration variation and/or cycle change; and

Figure 8 is a schematic representation graph of possible angular movements of said lever member plotted against switch action effects respectively capable of occurring in the course of one revolution of the cam in the illustrated embodiment.

- Referring to the drawings, my new switch mechanism may be secured to a panel 10 and placed in an instrument case cover (not illustrated).

' signal generated by a system such as a stoker control accordance with my invention is relatively rugged, rela tively uncomplicated in construction and relatively inexpensive. Further, by means. of this invention, 1 can, in resp nse to a. signal from an industrial or other system, vary the action e ec of my new switch mechanism in e ms of t e cycle. o that e ha sm, o in terms of the duration of switching action of that mechanism, or in terms of both such cycle and duration occurrences. Still further, if the control signal varies, th n rg l tion duration and/or. ycle currence. as the ca ay be i caused to correspondingly vary to satisfy the needs of the equipment assoc a ed with my n w sw ch m c ni m- As. an example, a combustion system control signal may system wherein the angular position of lever 11 would vary in accordance with variations in signal condition in that system. Thus, if steam pressure were selected as the signal condition to be responded to, a sufficiently high pressure indicative of no need for fuel, might cause the movements of lever 11 to stay within a zone l as shown in Figure 7 between schematic upper and lower boundary limits respectively numbered 15 and 16. A lesser steam pressure indicating load, and some demand for steam might cause the control signal of the combustion system to move lever 11 in Zone 2 shown on Figure 7 between schematic boundary limits 16 and 17 respectively. A still lower steam pressure, for example, might, in the illustrated embodiment, cause. the. control signal through rod 14 to move lever 11 within zone 3 between schematic boundary limits 17 and 18, respectively. Such zones are shown in Figure 7 for purposes of illustration only and the. zonal limits thereof tend to be somewhat graduated and. normally would shift in space with a change in characteristics of structural elements employed in one of my new switch mechanisms, and/or with a change in the characteristics of the control signal or system, as will be understood by those skilled in the switch mechanism art to whom this invention is disclosed.

Lever 11, as shown, is connected to panel by a pivot 19, between a post and a washer 21. Preferably, the opening through lever 11 for the passage of pivot 19 is hushed to minimize wear and eliminate lost motion or play between the pivot and lever 11 as lever 11 moves parallel to the face of panel 10. A slide 22 is adjustably fixed to lever 11 by headed screws 23 which pass through slots 24 in the slide. A boss 25 may be made integral with slide 22 and is provided with a vertically drilled and tapped opening 26. The threads of opening 26 engage the threads of an engagement screw 27 passing through opening 26. A knurled thurnb'piece 28 serves as a head for screw 27 to enable it to be turned in the course of any adjustment thereof to change the distance between point 29 and a reference location such as the underside of boss 25. A lock nut 30 threadably engages the stem of screw 27 so that when it is adjusted to correct length, lock nut 30 is turned to seat against the upper side of boss 25 to hold screw 27 in fixed adjusted position.

A mounting plate 31 is also connected to panel 10 by a pivot 32. A stop 33 and washer 34 on opposite sides of plate 31 act to keep the movement of plate 31 parallel to panel 10 in the illustrated embodiment. The hole in plate 31 through which pivot 32 passes is preferably provided with a bushing to eliminate play and avoid wear. Plate 31 may be stamped out of metal preferably light in weight such as aluminum or thin gauge steel. Plate 31 may be provided at one end with an outer extension 36 to serve as a foot in contact engagement, preferably at all times, with point 29 of screw 27. Hence, movement of lever 11 through its full amplitude between illustrated limits 15 and 18, or through any part of are 13, will provide a corresponding movement in plate 31 about the axis of its pivot 32 without lost motion and without chattering between point 29 and foot 36 regardless of the extent of the swing of lever 11 or the rapidity and direction of movements of lever 11.

Plate 31 may be stamped in such shape, moreover, as to provide a vertical bracket 37 to which an electrical switch 38 may be secured by bolts 39. Switch 38 is preferably a lightweight snap-action switch, such as those termed Micro-switch, and may be provided with an axially movable pin 40 which is capable of producing an action effect in switch 38 by an internal snap-action. In the illustrated apparatus, switch 38 is normally open and received its energizing action effect whenever pin 48 is within its action distance 56. As also shown in Figure 3, the movement of the bottom of a pin 40 through any part of any pretravel distance outwardly of action distance 56 creates no snapping on of switch 38 and therefore creates no action effect. Pin 40 is biased to rest on the upper side of switch arm 41 at all times.

When the end of pin 40 under the pressure exerted by a switch arm 41 is moved into the distance 56, it snaps switch 38 on closing an electrical circuit through terminals 42. Terminals 42 are respectively connected will be automatically increased to provide a closed switch action effect condition of ten times the shorter duration, or more. Moreover, since the new mechanism is responsive to dynamic, that is, to constantly varying control signal conditions, the switch 38 on period interval duration which will be the signal response will vary correspondingly between the shortest and longest interval duration achievable in any on cycle with a particular apparatus embodying my new principle.

Switch arm 41 is hinged between channel sides 46 of switch 38 by a pivot 47. Switch arm 41 is provided with a follower which in the illustrated embodiment is in the form of a depending roller 48 secured thereto. A spring 49 may be utilized to press arm 41 in a counterclockwise direction about pivot 47 as shown in Figure 1. A stop 58 is usually provided on the underside of the body of switch 38 to engage the rear end 51 of switch arm 41 as a part of a commercial snap-action electrical switch of the kind illustrated, although in the new combination of this invention illustrated, such stop 50 and extension 51 need not be utilized. It will also be apparent that other switch constructions may be purchased and substituted for the switch construction described in connection with the illustrated embodiment of my in vention.

In such embodiment, a revolving cam 52 is provided and frictionally secured to a drive shaft 53a having a reduced threaded outer portion 54a for a washer 55a and a thumb nut 56a between which cam 52 is readily so held. Thus, when nut 56a is tight, as shaft 53a rotates, cam 52 will also rotate without relative movement therebetween and yet is readily removable should the substitution of another cam be desired. As shown, cam 52 may be provided with two cam portions 53 and 54, both of which with connecting circular portions 55 form a peripheral track edge upon which follower roller 48 preferably rolls at all times and in all positions of my new switch mechanism.

Moreover, to the extent that either cam portion 53 and cam portion 54, or to the extent that cam portion 54 alone, causes switch arm 41 to move in a clockwise direction (considering Figure 1) about pivot 47 to an extent that pin 48 is moved upwardly beyond its pretravel limit into action distance 56, a switch action effect will take place which in the illustrated embodiment will close the snap-action electrical contacts inside switch 38 by insulated wires in an insulating sheath 43 to the respective panel terminals 44 which extend in insulated relation to panel 10 therethrough and through a terminal block 45. Panel terminals 44 may in turn be connected for the above-mentioned combustion system to fuel feeding and combustion air supplying equipment so that such fuel and air feeding will occur when switch 38 is closed and only so long as such is the case.

In the case of some newer coal grate mechanisms for boilers, the duration that switch 38 be closed may not be longer under some circumstances than about onequarter of a second, whereas under greater fuel demand conditions, the same switch mechanism interval duration and connect both terminals 42 in circuit. Conversely, the instant the outer end of pin 40 moves away from switch 38 a greater distance than the distance represented by the numeral 56, switch 38 will snap open to its normally open condition. Hence, whenever the angular position of plate 31 about its pivot 32 is such owing to the.angular position of lever 11 about its pivot 19, that a switch closing (action effect) takes place (which in the illustrated embodiment would occur upon engage- .ment of follower 48 with an appropriate cam portion as schematically represented by zones 2 and 3 in Figure 7), there is an on period interval duration which is a function of the time that either or both cam portions, as the case may be, maintain the end of pin 40 within the action distance represented by the numeral 56. Significantly, that switch action effect condition in which switch 38 is closed may be practically instantaneous in length and conceivably might occur when follower 48 is in engagement with any part of either cam portion 53 or.of cam portion 54 dependent upon the position and condition of movement of lever 11 at the time being. Thus, lever 11 and plate 31 may vary in position even when a longer action effect is produced by engagement between follower 48 and cam portions 53 and 54. As an illustration, if, for example, a switch 38 snap closing is effected when the point of contact is at point A between follower 48 and the cam rise face of cam portion 53, a point B might represent the correspendin point of contact on the: cam: fall: face on. the portion 53- at which switch 38' opens: and the on? period duration interval would represent thetime' it took follower 48 to move from: A over peak 57 to point B if the position of plate 31- and lever 11. remained substantially steady. However, since members 11 and 31 are free to'move in response to'a' control signal, the interval= duration during' which switch 38 is closed would betshortened if the position of plate 31 at the time the contact at point B. occurs is above, that is, hasa position which isangular-1y clockwise of the position which plate 31"- had at the time of the point A contact. Conversely, the intervalduration during which switch: 3%: is closed wouldbe lengthened if the position of plate 31f at the time the contact at point B occurs is below; that-is; has a'positi'on which is'angularly counter clockwise of the position which plate 31 had at the time of the pointA' conta'ct For initial adjustment at the time that cam 52 is attached by hot 56a to shaft 53a; or for calibration or data recording purposes, the front of cam 52' may be marked with angular divisions 59 to serve in conjunction withan: index pointer 60 to mark time or degrees of angular position. To removeor replace a cam like cam 52; abol 'fi one may be loosened to enable pointer 60 to be swung out of way on post 60b;

In the illustrated embodiment, shaft 53a is hushed in a post of; secured to the front of panel 10; The shaft 53a extendsthrough panel 1*0 and in the illustrated embodithem is drivenby a synchronized motor 62 usually having a gear train within a case; like case 63 as an" energy source or control to drive shaft 53a and therebycam 52 at a predetermined number of revolutionsv per unit of time. Thus; if motor 62 is so calle'd two-minute motor, camS'Z will make one complete revolution, which, ale-illustrated, is in thedirection of arrow 64, every two minutes in which event markings 59. may constitute one hundred twenty in number. Instead of being. driven by a synchronized motor, a shaft like shaft 53a in one of my new mechanisms may instead be connected for rt'ation under the influence of a second control signal whereby the action of a switch like switch 38 in the new mechanism would be a function of two variable control signals. In the" illustrated embodiment, the new mechanism is responsive to but" a single variable control signal impressed uponv lever 11. Further, in the illustration, wires 65' connect motor 6 2' to motor. terminals 66 at the front of panel ll) so that the motor may be connected to a suitable electrical power source.

It will also be apparent to those to whom this inventionis disclosed that other sequences and variations in switch action interval duration, or in cycle number, or in both, in connection with a combustion system control signal as described herein, or in connection with a control signal from any of, a number of other possible applications for my invention, may be provided by substituting a different cam, for example, on shaft 53a, or by substituting another motor for motor 62, or by making other modifications which will occur to those to whom my invention is disclosed. Further, although switch 38 is normally open, my new mechanism may readily be arranged to utilize an electrical switch which is normally closed. Still further, although in the illustrated embodiment, a revolving cam is shown, such camming may be obtained by an endless belt operating around sprockets with cam ridges thereon. Moreover, it will be apparent to those to whom this invention is disclosed that a variation in the sequence and/or action effect provided by this invention may be also achieved by a variation in cam contour as, for example, a change in the slope of the cam rise and/or fall portions. Although in the illustrated embodiment the cam; fall faces of cam portions. 53? and 54 are sloped, rather than abrupt, in order to minimize any possibility of backlash, it is possible to; obtain. gears: which; are free: from backlash in which event the: cam. fall: face of cams. utilized in; my new mechanism: may more readily be made abrupt. In the illustrated embodiment. further, it will be apparent that if a four-minute. motor were utilized in place of two-minute motor 62, for an otherwise similar control response operation, a cam. would be provided in place ofcamv52'havingfourcam= portions spaced 9.0T apart.

In operation, the: illustrated embodiment may be utilized to change the cycle, or the interval duration,v of the on period of. a combustion system in. accordance with the needs of that system. Thus, if a; control signal is used from the system based, for example, on the pressure of steam: generated by a" boiler in thatsystem, such stearnmight be." available at sufiiciently high pressures to maintain: rod 14' and.thereby'movement oflever H substantially in' zone' 1 of Figure? which for illustrative purposes mightbe deemed to be represented on the chart of Figure 8 at the distance between a: datum line marked: W and a line: marked X at the peak of thelarger cam 54; The Figure 8 chart is inserted for purposes of explanation and" not by way of limitation in view of the: many forms which my invention may take; Further, in all z-ones, foot 36' is held against point 25 without chatteringbecause the force of switch arm acting through spring 49 issufficient for that purpose an all times regardless of the movement of lever 11. Moreover; in adjusting the new device, the lengthening of screw 27' by screwing it down into boss 25 would move plate 31 counterclockwise about its pivot 32 as seen in Figure l, the effect being to shift the line W of the Figure 8 chart upwardly toward the cam peaks and to reduce thean'gular distance between boundaries E5 and IE6 thereby reducing or even eliminating zone 1 as may be desired. Conversely, shortening screw 2'7 to allow foot 36 to' move upwardly relative to lever 11 would increase the angular distance in which a zone 1 effect would obtain. Thus, because of the location of the centers in the illustrated embodiment, the effect of a change in the length of screw 27 is to shift the chart shown in Figure 7 about its center, although the actual amplitude and angle through which lever 11 may swing under the influence of'a system control signal may remain unchanged.

In addition, the adjustment of slide 22 to the left, as shown in Figure 1, will somewhat decrease the angle of swing of plate 31, other conditions remaining'the same and vice versa. Hence; adjustments provided for by screw 27 and/or slide 22 constitute means in addition to cam contours and height for obtaining precise regulation between the switch action effect of switch 38 and the control signal impressed on lever 11 to which such switch action is to be responsive.

As described above in connection with any zone 1 which may exist, the combustion system control signal remains effective throughout but there is no on period for the illustrated embodiment of my switch mechanism in that zone 1 and the switch mechanism therefore idles when lever 11 is therein with plate 31 in corresponding position. The absence of any need for such an on period while lever 11 moves in zone 1 might indicate that there was sull'i cient fuel on the grate of a furnace in the control system so there would be no feeding of fuel if the terminals 4 of switch 38 were connected, for example, so as to energize a motor to feed coal to such grate whenever switch 38 is closed and inv its action position. In certain modern industrial coal furnaces, the on period even for regular load demands can be quite short re. quiring a quick-acting control device of a kind such as that provided by my invention. The device of my invention may be interconnected with other regulatory devices and its action might be suspended, for example, when a live fuel bed is being started in such a furnace or during periods; when the fire might be banked.

A change in the angular dimension of zone 1 would correspondingly shift the illustrative upper boundary 16 of zone 2. Further, my new device is flexible enough in construction so that an illustrative boundary like line 17 between zones 2 and 3 can also be shifted, as, for example, by screwing screw 27 down, or by increasing the height (radial distance from the axis of shaft 53a) of peak 57 on cam portion 54 relative to the existing greater height of peak 58 on the respective larger cam portion 54. As shown, the illustrative setting of the embodiment depicted herein is such that when lever 11 is in zone 2 (and plate 31 correspondingly positioned), engagement of follower 48 with the camming faces of cam portion 53 never causes the outer end of pin 40 to move within the switch action effect condition distance 56 shown in Figure 3 and the end of pin 40 remains in inaction position along its pretravel path. The result is that in zone 2, I provide but one on period cycle per revolution of cam 52 when cam portion 54 engages follower 43 although within the length of the cam rise and fall faces of cam portion 54 inclusive of peak 58, an almost innumerable interval duration variation can occur when switch 38 is closed and can change while switch 38 is closed. If such closing of switch 38 occurs only, for example, about at the instant of contact between follower 48 and peak 58 as when lever 11 is about in the position of illustrative boundary 16, the on or action effect period of switch 38 will be practically instantaneous and suitable for some applications to which my invention may be put. For illustrative purposes, the boundary lines 15 to 18, respectively, in Figure 7 may be indicated as W degrees, X degrees, Y degrees and Z degrees, the same degree markings being shown on the abscissa lines in the chart in Figure 8. In the chart of Figure 8, a small bar 67 at the X-degree line may represent such a practically instantaneous interval of closed switch condition obtainable at peak 58 by the embodiment shown. Further, a practically instantaneous interval duration is obtainable in zone 2 substantially anywhere along the cam rise face or cam fall face of cam portion 54 dependent upon the condition of movement of lever 11 and consequently of plate 31 and switch 38. By the same token, an action position can change into an inaction position, and vice versa, or the interval duration of any thereof may change as lever 11 and plate 31 respond to a change in the control signal. Hence, the new device quickly follows and is sensitively responsive to whatever need is reflected by the control signal condition and by any change therein.

Because both the cam rise face and the cam fall face of cam portion 54 are sloped, a part of that duration interval in zone 2 positions for lever ll and plate 31, extend across the vertical dash line 76 representing a radial line through the cam crest 58. Switch action caused by cam portion 54 in the lever 11 and corresponding plate 31 positions between X degrees and Y degrees are also illustrated as bars 68, 69 and 70, such being with bar 67 between four of the almost limitless variations that can occur in the on period duration interval that can occur in the functioning of my device. As shown, interval durations represented by bars 67 to 70, inclusive, indicate a steady situation without material movement of lever 11 during each such interval duration whereas in practice such movement may be likely to occur and would correspondingly change such interval duration.

Operations within the illustrated zone 2 will occur, for example, when steam pressure is lower and there is one demand for more fuel in each full revolution of cam 52. Whenever such steam pressure becomes too low requiring a greater amount of fuel in the illustrative cornbustion system, the control signal therefrom will move lever 11 to the border between zones 2 and 3 (see bar 70), or into zone 3, illustrated in Figures 7 and 8, whereupon my new switch mechanism provides both a cycle change and on period interval duration variation. Thus,

in zone 3, the position of plate 31 is such that switch arm 41 will be caused by both cam portions 53 and 54 to move pin 40 within the switch action energization distance 56 so that there will be two on period intervals under zone 3 conditions for each single revolution of cam 52. Thereby, cam portion 53 is made effective and produces an on period response by the closing of switch 38. Thus, if cam porton 53 produces an action effect at its peak as represented by bar 71, there will be two cycles or on periods per single revolution of cam 52, the respective durations of which may be represented by bars 71 and respectively. The more that lever 11 is in zone 3 and closer to its Z-degree position, the greater the likelihood the interval duration for each on period produced by cam portion 53, and for that matter by cam portion 54, may be correspondingly longer, as shown in the case of cam portion 53 by bars 72 to 74,- inclusive, respectively. Similarly, bars 77 to 79, inclusive, respectively represent the possibility of increased interval duration producible by cam portion 54 as lever 11 and therefore plate 31 approach their respective positions corresponding to the Z-degree position in zone 3. Bars 73, 77 and 73 illustrate respective interval durations in which there has been a movement of lever 11 during the occurrence of the particular switch energization interval, although in the illustrated instances of bars 73, 77 and 78, lever 11 did not move out of zone 3 during such movement while there was contact between follower 48 respectively with the cam portions 53 and 54. The vertical line 75 represents a radial line through the center of cam 52 and the crest 57 of cam portion 53. Whenever cam portion 53 is effective, its mode of functioning relative to the balance of my new device is similar to the mode of functioning of cam portion 54. In addition, Figures 4, 5 and 6 illustrate possible instantaneous positions of my new switch mechanism in zones 1, 2 and 3, respectively.

Thus, so long as lever 11 remains in a zone 3 position, the duration interval produced by cam portion 54 will be longer than when lever 11 is in a zone 2 position. On the other hand, lever 11 may move into any other zone after any switch closing caused by either cam portion and correspondingly vary the functioning of my new switch mechanism. For example, if after a zone 3 position contact between follower 48 and cam portion 53, lever 11 moves into a zone 1 position before cam portion 54 engages follower 48, there will be no effective action caused by cam portion 54. However, if lever 11 has moved into a zone 2 position by the time cam portion 54 is so reached, then the interval duration which occurs will close switch 38 but only in accordance with an interval between the X-degree and Y-degree positions on the chart of Figure 8 so long'as lever 11 and plate 31 remain in a zone 2 condition.

Still further, lever 11 may be in a zone 3 position, with plate 31 in a corresponding position, at the beginning of action effect engagement between follower 48 and cam portion 54 with the initiation of an interval duration such those illustrated between the Y degrees and Z degrees on Figures 7 and 8. Should such lever 11 move into a zone 1 or 2 position after such engagement with cam portion 54 and by the time cam portion 53 is reached, there would then be no action effect or on period produced through switch 38 in the illustrated embodiment.

Thus, in my invention, numerous permutations and combinations are achievable which are adaptable to the particular needs of a variable control signal in different kinds of systems. Numbers of changes may be made in elements and parts of my new switch mechanism without departing from the spirit of my invention or the scope of the appended claims.

I claim:

1. In a switch mechanism, a panel, a lever pivotally mounted on said panel, said lever being responsive to a signal from :arcombustionrsystem or :thedike, ta tslide :ad- .iiu'stably zconnected to said slever, 'aniengagement screw tadjustablytconnected :to -'said slide, a mounting plate piv- ;,Zationofsaid switch varies in relation-to the spatial tpositions and movements of said lever.

2. In a switch mechanism having a panel, a movable lever responsive to a signal, a mounting plate pivotally connected to said panel, a snap-action switch mounted on said plate, a switch arm in said switch capable of holding said mounting plate in engagement with said lever, said switch arm having a cam follower and being capable of movement through a pretravel range and an action range, a timer motor, a rotatable cam driven by said motor and 'in engagement with said cam, said cam having at least one cam portion having a taper in a radially outward direction, whereby a change in the position of said lever changes the position of said follower relative to at least one of said ranges and the interval duration relation between said ranges.

3. In a switch mechanism, apparatus comprising, in combination, a member movably mounted in said mechanism and adapted to move in response to variations in a signal, first means movably mounted in said mechanism adjacent said member, a switch in said first means, means for causing said first means to operatively exert pressure relative to said member for movement of said first means as and when said member moves, cam means'movably mounted in said mechanism adjacent said first means, means for moving said cam means, means for causing said first means to operatively exert pressure relative to said cam means, said first means substantially extending between said member and said cam means and further including flexible means to accommodate changes in the space between said member and said cam means, whereby actuation of said switch is responsive to predetermined spatial positions of said member and cam means relative to one another.

4. In a switch mechanism, apparatus comprising, in

combination, a lever pivotally mounted in said mechanism'and adapted to move in response to variations in a signal, a member pivotally mounted in said mechanism adjacent said lever, a switch mounted on said member adjustable means to cause said member to operatively exert pressure against said lever for movement of said member as and when said lever moves, a cam rotatably mounted in said mechanism adjacent said switch, means for rotating said cam at a predetermined rate, and a follower continuously in engagement with said cam and extending between said cam and said switch, said follower being adapted to actuate said switch when said cam is within a predetermined distance thereof.

5. In a switch mechanism, in combination, a movable first member, means for moving said first member in response to a signal, a movable second member engaging said first member and adapted to be moved when said first member is moved, a switch mounted on said second member, a switch arm carried by said switch, said switch arm having an action position, and a movable third member engaged by said switch arm, said third member having a path of travel and an irregular configuration such that said third member may cause said switch arm to move into action position for varying interval lengths of time dependent upon the relative position and condition of movement of said first member.

6..In a switch mechanism, in combination, a member movable in response to a control signal, a second memratiomas rto-timeof occurrence ganddurationof :the interval of aid action tpcsi iqu corre ponding to Sa d on l :signal.

7- I-n a.- itch me hanism, tin-combinat on, zmov bl first member ,mounted ,in .said mechanism .and responsive to a signal, a movable second member mounted in said mechanism for engagement by said first member so that when said first member moves said second member is moved at the same time, a switch mounted on said second member and having an actuator movable through a non-actuating pretravel distance with movement of said actuator beyond said pretravel distance actuating said switch, a switch arm mounted on said switch to contact said actuator, a movable third member mounted in said mechanism and having at least one peripheral cam portion, said second member and switch substantially extending between said first and third members,-said switch arm being adapted to engage the periphery of said third member to move said actuator, and means for moving said third member, whereby duration and periodicity variations in any actuation of said switch are dependent upon the respective positional interrelationships of said members.

8. In a switch mechanism, in combination, a movable first member mounted in said mechanism and responsive to a signal, a movable second member mounted in said mechanism in constant engagement with said first memher so that when said first member moves said second member is moved at the same time, means for adjusting such engagement between said first member and said second member, a switch mounted on said second member and having an actuator movable through a non-actuating pretravel distance with movement of said actuator beyond said pretravel distance actuating said switch, a switch arm mounted on said switch and in constant contact with said actuator, a rotatable third member mounted in said a mechanism and having a periphery with at least one cam.

portion, said second member and switch substantially extending between said first and third members, said switch arm being in constant engagement with said periphery to move said actuator, and means for rotating said third member, whereby duration and periodicity variations in any actuation of said switch are dependent upon the respective interpositional relation among said members.

9. -In a switch mechanism variable as to duration of actuation or frequency of actuation or both, in combination, a pivotally mounted lever responsive to a signal impressed thereon to move said lever about said pivot, a pivotally mounted mounting plate movable generally in the plane of said lever, a contact member extending between said lever and said plate to move said plate about its pivot in simultaneous accordance with movements of said lever, a cam member having a periphery movable through a path of travel adjacent said plate, the periphery of said cam having normal non-actuation portions and camming portions therealong, a switch mounted on said plate and movable therewith, an actuating pin for said switch having a non-actuating pretravel zone and an actution zone, and a yieldable switch armconnected to said plate to follow closely the periphery of said cam and to move said pin, said camming portions having sloping sides and extending for predetermined heights, whereby said plate and switch float between constraints respectively exercised by said contact member and cam for correspond- 10. In a swtch mechanism, in combination, a movable lever, means for moving said lever in response to a signal, a movable plate engaging said lever and adapted to be moved when said lever is moved, a switch mounted on said plate, a switch arm for said switch having an action effect within a predetermined distance thereof, a movable cam having at least two cam rise portions on its periphery to engage said switch arm, said cam portions having an outwardly tapering configuration and having respectively different camming distances measured from the movement center of said cam, said plate and switch substantially extending between said lever and cam, whereby as said lever and therefore said switch move away from '12 saidc'am'the tendency is to first render at least'the smaller cam portion ineffective insofar as any action efiect is concerned and to shorten any action effect provided through either cam portion, and vice versa.

References Cited in the file of this patent UNITED STATES PATENTS 2,553,299 Carr May 15, 1951 2,633,914 Miller Apr. 7, 1953 2,653,196 Cockman Sept. 22, 1953 FOREIGN PATENTS 900,567 France Oct. 9, 1944 UNITED STATES PATENT ormei E CERHHCATE @315 @URREQTWN Patent Nob 2,853 ggptembgl Paul Koek It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below,

Column 9 line 51,, after "member" insert comma; eoiunm 10, line ee,

for "aotu read aotua (2011mm 1.1 line 1 for "SW-toil" reed Signed and sealed this 6th day of January 1959 SEAL) nest:

' KARL H AXLINE ROBERT C. WATSQN Attesting Uflicer Commissioner of Patents UNITED STATES PATENT UFFICE CERTIFICATE @F QORRECTIUN Patent N00 2,853,567 September 23, 1958 Paul Q 3 Kook It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 99, line 51,, after "member" insert comma; column 10, line so,

for "actu read M eotua== column 11, line 1 for "swtoh" read an switch e Signed and sealed this 6th day of January SEAL) ttest:

- KARL Ho AXLLINE RGBERT C. WATSON Commissioner of Patents Attesting Oificer

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