US2773548A - Timing device of the resettable and variable type - Google Patents

Description

Dec. 11, 1956 N. F. THOMPSON 3RD., ETAL 2,773,548

TIMING DEVICE OF THE RESETTABLE AND VARIABLE TYPE Filed April 22, 1954 United States PatentO TIMING DEVICE or THE RESETTABLE AND VARIABLE TYPE Application April 22, 1954, Serial No. 424,964

7 Claims. (Cl. 161-1) This invention relates to timers in general, and to variable timers of the resettable kind in particular.

The timer with which the present invention is concerned is of the type shown and described in the copendingapplication of Norman P. Thompson, Serial No. 424,618, filed April 21, 1954. This prior timer is designed to form a part of or be associated with a device whose period of operation is to be selectively controlled. In the specific example given by way of illustration in the aforesaid application, the timer forms a part of a bread toaster to control the duration of the toasting operation, although the timer may obviously serve to control the period of operation of a great variety of other devices. In this prior timer, a timing element in the form of a reciprocating rack is advanced from a starting position by a suitable power drive to cooperate with a pivotally mounted operating member, moving the latter into a terminal position from a set position at the completion of a selected time interval of operation. Movement of the operating member into such terminal position is employed to mechanically actuate the device under the control of the timer, and simultaneously to interrupt the drive to the timing element so that it may return to a starting position and be ready for a new cycle of operation. Selection of the duraton of the timing cycle of operation is afforded by providing on the operating member an adjustable'cam with which the timing element coacts to move the member to its terminal position. In the prior device, this cam is carried by the operating memberfor movement radially of the pivot axis of the latter, and cooperating with the cam is a pivoted shifter arm which may manually be turned to move the former into an infinite number of adjustments on the operating member. Moreover, the cam, its adjustment range on the operating member, and the timing element are so coordinated that the cam may be moved by the shifter arm to cause immediate movement of the operating member to its terminal position at any time and, hence, permit premature termination of any operating cycle of previously selected duration.

1 It is an object of the present invention to provide a variable timer of this type of which both the timing element and the adjustable element on the operating member are cams which may be designed to achieve most any desired movement of the operating member to its terminal position, such as substantially uniform motion, approximate harmonic motion, variable motion and snap motion, for instance, as well as a variety of other motions.

It is another object of the present invention to provide a variable timer of this type of which the cam element on the operating member is pivotally mounted thereon and is angularly adjustable, thereby to achieve an exceptionally wide range of possible operating cycle variation with a minimum of bulk.

It is a further object of the present invention to pro vide a single bearing for the pivotal support of the operating member and also for the journal support of a pinion ,coaxially of the pivot support of the operating 2,773,548 Patented Dec. 11,

member, and to further provide the pivoted cam element as the operating inember with a gear segment which is in mesh with the aforesaid pinion, thereby achieving not only exceeding structural simplicity of the timer and ready assembly of these parts with the rest of the timer, but also accurate and immediate response to any turn of the pinion of the cam element in its adjustment on the operating member.

Further objects and advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a side elevation of a variable timer embodying the present invention;

Fig. 2 is an end elevation of the same timer as viewed in the" direction of the arrow 2 in Fig. 1;

Fig. 3 is another side elevation of the timer as viewed in the direction of the arrow 3 in Fig. 2;

Fig. 4 is another end elevation of the timer as viewed in the direction of the arrow 4 in Fig. 1;

Fig. 5 is a section through the timer as taken on the line 55 of Fig. 4;

Figs. 6, 7 and 8 are fragmentary side elevations of the timer, showing certain parts thereof in different operating positions; and

Fig. 9 is an enlarged fragmentary section through the timer as taken on the line 9-9 of Fig. 1.

Referring to the drawings,'the reference numeral 20 designates a timer which for purposes of illustration, is adapted to control the operating cycles of a bread toaster. As shown here, the timer comprises an operating member or trigger 22, as it will be referred to hereinafter for convenience, a timing element 24, a power drive 26 for the timing element (Figs. 2, 4 and 5), and a drive control 28, all of which are provided in or on a timer frame 30. The timer frame 30 comprises, in this instance, opposite end plates 32 and 34 which are held in spaced parallel relation by a plurality of pillars 36.

The trigger 22 is in the form of an arm which, as shown in Fig. 9, is pivotally mounted on a diametrically reduced portion 37 of a bearing 38 on the frame plate 32. The trigger 22 is normally urged by a return spring 40 into a maximum set position (Figs. 1 and 7) in which a bent lug 41 on the trigger 22 bears against one end of an arcuate slot 42 in the frame plate 32. The return spring 40 is anchored with its ends on the frame plate 32 and trigger 22, respectively. The trigger 22 is turned into its set position to start an operating cycle of the timer, as will be more fully described hereinafter. Conversely, an operating cycle is terminated when the trigger 22 is shifted from its set position in Figs. 1 or 7 into its terminal position in Figs. 6 or 8 by the timing element 24 in a manner described hereinafter.

In the present example, the trigger 22 is, through intermediation of a lever 44, operatively connected with a latch bar 46 on the usual toaster rack (not shown). The lever 44 may conveniently be pivoted at 48 on a toaster frame (not shown) in which the present timer is suitably mounted and the aforementioned toaster rack is customarily depressible for toasting purposes and released for spring-return to a raised position at the end of a toasting cycle. In this instance, the timer 20 is conveniently mounted, by lugs 49 on its end plates 32 and 34, on a plate 51 of the toaster frame.

The lever 44 has two arms 52 and 54 which carry a follower pin 56 and a latch pin 58, respectively. The follower pin 56 projects into the bifurcated end 60 of the trigger 22, while the latch pin 58 projects into a longitudinal slot 62 in the latch bar 46. The slot 62 in the latch bar 46 has a straight portion 64 and an oifset por- (J tion 66, and the latch bar is normally urged into its uppermost position (Fig. 6) due to its explained connection with the spring-urged toaster rack. However, the latch bar 46 will, in the depressed position of the toaster rack, prevent the pop-up of the latter when the trigger 22 is in any position other than its terminal position and holds the lever 44 so that its latch pin 58 is somewhere in the offset slot portion 66 and locks with the latch shoulder 70 on the latch bar (Fig. 1). When the trigger 22 is thereafter shifted into its terminal position (Figs. 6 and 8) the lever 44 will also be shifted to bring its latch pin 58 from interlock with the latch shoulder 70 into alignment with the straight slot portion 64 in the latch bar 46, whereupon the latter and the toaster rack are released from their depressed position and permitted to pop up. A suitable switch (not shown) for the control of the usual heating elements in the toaster may automatically be opened in any suitable manner on the pop-up of the toaster rack to terminate a toasting cycle. In depressing the toaster rack by any of the conventional means provided for that purpose, the latch bar 46 is lowered sufficiently to permit the lever 44 and the trigger 22 to swing into the respective positions shown in Figs. 1 and 7 under the urgency of the trigger spring 40, returning thereby the latch pin 58 on the lever 44 into interlock with the latch shoulder 70 on the latch bar 46 and, hence, preventing the pop-up of the toaster rack until the trigger 22 is again shifted into its terminal position. The aforementioned switch for the heating elements in the toaster may automatically be closed in any suitable manner on depression of the toaster rack to start a toasting cycle.

The timing element 24 is, in the present instance, in the form of a cam on a staff 72 which is suitably journalled in the end plates 32 and 34 of the timer (Fig. 4). A torsion spring 74, which is anchored with its ends to the frame plate 34 and an anchor plate 76 on the staff 72 (Fig. 4), normally urges the latter in a direction to return the timing element 24 into a starting position in which the same bears against a stop 78 on the frame plate 32 (Figs. 1, 7 and 8).

The power drive 26 of the timing element 24 comprises a reduction gear train 80 which is driven by any suitable prime mover or power source, such as a synchronous motor 82, for instance (Figs. 2, 4 and The gear train 80 has the previously mentioned output shaft 72 which carries the timing element 24. The motor 82 is suitably mounted at 86 and 88 in the timer frame 30, and its rotor shaft 90 carries a gear 92 which forms a part of the gear train 80. Starting from the motor 82, the gear train 80 has successive stages of speed reduction in the gear parts 92 and 94, .96 and 98, 100 and 102, 104 and 106, 108 and 110, and 112 and 114. As already mentioned, the gear 92 is carried by the rotor shaft 90 of the motor 82. The next succeeding sets of unitary gears 94, 96 and 98, 100 are carried by suitably journalled staffs 116 and 118, respectively, in the timer frame 30. The unitary gears 102, 104 of the next set are freely rotatable on a fixed staff 120 in the timer frame 30. The unitary gears 106, 108 of the next set are carried by a staff 122 which is not only journalled in the timer frame but is also axially movable therein for a purpose described hereinafter. The unitary gears 110, 112 of the next set are freely rotatable on the same fixed staff 120 on which the gears 102, 104 of the previously mentioned set are also freely rotatable. Finally, the end gear 114 of the train is carried by the output shaft 72. Any suitable means, such as the collars 124 and 126 may be provided on the fixed staff 120 in order to prevent axial motion of the gear sets 102, 104 and 110, 112 thereon.

The gear train 80 is also provided with a normally engaged clutch which is disengaged to interrupt the gear train 80 at the end of each operating cycle and between successive operating cycles, and which is engaged during each operating cycle. This clutch is, in the present instance, constituted by the axially immovable gear and the gear 108 on the axially shiftable staff 122, and Fig. 2 shows this clutch engaged by virtue of the meshed relation of these gears. The staff 122 may be shifted to the right as viewed in Fig. 2 to demesh the gear 108 thereon from the gear 110 on the fixed staff without demeshing the gears 106 and 104, and thereby interrupt the gear train.

The shiftable staff 122 is normally urged, by means of a leaf-type spring 130 on the frame plate 34 (Fig. 2), into clutch-engaging position in which a collar 132 thereon bears against the frame plate 32 and the gears 108 and 110 are in mesh with each other. The staff 122 is shifted at the proper times into clutch disengaging position, to demesh the gear 108 from the gear 110 and thereby interrupt the gear train, by means of the aforementioned control 28 which is in the form of a punched-out cam lug on the trigger 22. This cam lug is so arranged (Fig. 2) as to depress the adjacent end 136 of the staff 122 and demesh the gear 108 from the gear 110when the trigger 22 is shifted into its terminal position to terminate an operating cycle (Figs. 6 and 8), and to release the end 136 of the staff 122 and permit the latter to be spring-urged into its clutch-engaging position for reme'sh'of the gear 108 with the gear 110 (Fig. 2) when the trigger is shifted from its terminal position toward its set position for starting an operating cycle. The timer described so far is in most essential respects like the timer shown and described in the aforementioned copending application Serial No. 424,618, except that the present timing element 24 is a cam.

The instant timer 20 is also of the variable type, i. e. its operating cycles may be of. variable duration. To this end, the timing element 24 does not directly cooperate with the trigger 22, but acts through intermediation of an adjustable cam element 140 on the trigger, in shifting the latter into its terminal position for the termination of an operating cycle. It is this cam element 140 and its adjustability on the trigger 22, coupled with the cam form of the timing element 24, which form the major part of the present invention. The cam element 140 is pivotally mounted at 142 on the trigger 22. For its angular adjustment on the trigger 22, the cam element 140 is provided with a gear segment 144 which is in mesh with a pinion 146 (Figs. 1, 2 and 9). The pinion 146 has a shank 148 which is journalled in the aforementioned hearing 38 on which the trigger 22 is pivoted coaxially of the pinion 146 (Fig. 9). The shank 148 of the pinion 146 is retained in the bearing 38 by means of a disc 150 which is interposed between the frame plate 32 and a snap ring 152 on the shank 148. The disc 150 is a spring disc which holds a mounted flange 154 on the pinion 146 in engagement with the adjacent end of the bearing 38 with sufficient friction to resist rotation of the pinion 146 unless the same is manually turned with some force for intended angular adjustment of the cam element 140 on the trigger. The pinion 146 is also provided with a slotted hub 158 for connection with a knob (not shown) with which to turn the pinion 146 whenever the cam element 140 is to be angularly adjusted on the trigger.

The element 140 is provided with a contoured periphery forming a cam surface 160 which confronts and is in operative alignment with the timing element 24, and is engaged by and compelled to follow the latter on its power drive in an operating cycle until the trigger 22 is turned to its terminal position for the termination of the operating cycle. The gap (Fig. 7) between the timing element 24 in its starting position and the cam element 140 in the maximum set position of the trigger 22, at the start of an operating cycle, will vary with the angular adjustment of the cam element on the trigger, with the result that the ensuing operating cycle will also vary with the adjustment of the cam element.

The angular adjustment range of the cam element-140 on the trigger 22 isnot so limited asto'leavea gap between it and the timing element'24 every time the trigger is shifted from its terminal position for the start of an operating cycle, neither may the trigger be shifted 'all'the way to its maximum set position (Figs. 1 and 7) for the start of every operating cycle. Thus, the cam element 140 may be adjusted on the trigger to the extent shown inFig. 1, for instance, such that the former will, on shifting the latter into its maximum set position, engage the timing element 24 substantially in its starting position, with the result that the ensuing operating cycle will be of considerably shorter duration than that resulting from the adjustment or setting of the cam element in Fig. 7. The cam element 140 may be adjusted even further, clockwise from the position shown in Fig. 1, so that the same will engage the timing element 24 in, or substantially in, its starting position when the trigger 22 is shifted from its terminal position into a set-position which is anywhere between the latter position and its maxmum set position, with the result that the ensuing operating cycle will be even shorter in duration than that resulting. from the exemplary adjustment of the cam element in Fig. 1.

It thus follows from the preceding that the angular adjustability of the cam element 140 on the trigger 22 affords an infinite number of time interval variations Within a wide range. The cam element 140 may, through manipulation of the aforementioned knob on the pinion 146, be adjusted for a desired time interval before the same is started, or may be adjusted during an operating cycle to vary the same as desired. Furthermore, the cam element 140, its angular adjustment range on the trigger 22, and the timing element 24, are so coordinated that any started operating cycle may instantaneously be terminated at any time. In this connection, let it be assumed that an operating cycle of maximum possible duration has been started, and that it is desired to terminate the cycle immediately after its start. This may readily be accomplished by merely turning the cam element 140 into the position shown in Fig. 8 so that the same will react with the timing element 24 and shift the trigger into its terminal position before the timing element has been driven through an appreciable angular distance, if any, from its starting position. Since an operating cycle of maximum possible duration may instantaneously be terminated immediately after its start, it follows that all possible selected time intervals of timer operation may instantaneously be terminated at any time aftertheir start.

Following is a description of a cycle of operation of the instant timer in connection with the toaster with which it is associated in the present example. After angularly adjusting the cam element140 on the trigger 22, to the extent shown in Fig. 1, for instance, for the desired duration of the time interval of timer operation to follow, the operating cycle is started by depressing the toaster rack, with the result that the trigger 22 is permitted to shift into the set position shown in Fig. 1 under the urgency of its return spring 40, and the toaster rack will for the duration of the timer cycle be held in its depressed position by virtue of the interlock of the latch pin 58 on the lever 44 with the latch shoulder 70 on the latch bar 46. Immediately after the trigger 22 leaves its terminal position in its shift toward its set position, the cam lug 28 thereon withdraws from the depressed staff 122 (Fig. 2) and permits the latter to be shifted by the leaf spring 130 into its clutch-engaging position to bring the gear 108 thereon into remesh with the gear 110 and thereby restore the gear train 80 and impart it drive to the timing element 24 for the advance of the latter from its starting position (Fig. 1). In this exemplary operating cycle the timing element 24 will immediately on its advance from starting position cooperate with the cam element 140 in shifting the trigger 22 from its set position toward and into its terminal position. The trigger 22 will, in the course of its advance toward its terminal position, rock the lever 44 so that its latch pin 58 will move on the latch shoulder 70 closer toward alignment with the straightslot portion 64 in the latch bar 46. When the timing element 24 finally shifts the trigger 22 into its terminal position, the latch pin 58 on the lever will be in alignment with the straight slot portion 64 in the latch bar 46 and permit the latter and the associated toaster rack to pop. up and thereby terminate an operating cycle of the toaster. Further, when the trigger 22 reaches its terminal position the cam lug 28 thereon will have depressed the staff 122 sufiiciently to demesh the gear 108 from the gear 110 and interrupt the gear train to terminate the timing operation and permit the spring 74 to return the timing element 24 to its starting position.

It follows from thepreceding that the gears 114, 112 and 110 of the train will be driven, counter to their normal drive, on the spring-return of the timing element 24 to its starting position, while the remaining gears of the train will not interfere with the return of the timing element regardless of whether they are driven by the motor 82 between successive operating cycles, or are at rest if the motor should be shut off in any suitable manner on the pop-up of the toaster rack. The few reduction gears 114', 112 and 110, which are reversely driven by the timing element 24 on its spring-return to starting position, constitute an effective brake for the timing element so that the same will not be forcefully snapped back into its starting position but will rather gradually return thereinto. This hesitancy and delay in returning the timing element 24 to its starting position does not in the least interfere with desired rapid repeatcycle performance of the timer for the following reason. The trigger 22 remains in its terminal position until the next operating cycle is started and the gear train 80 remains interrupted until then, wherefore the timing element 24 has available the entire period between successive cycles of the timer to return to its starting position. The gradual, rather than a quite sudden, return of the timing element 24 to its starting position not only protects it and the parts connected therewith from harmful jarring and undue wear, but also assures that the timing element is in its starting position and rests against the stop 78 at the time the next cycle is started and, hence, assures high accuracy of the duration of the next operating cycle in conformity with the setting of the timer.

Due to the explained frictional resistance of the pinion 146 against turning, the gear segment 144 of the cam element will slightly roll on the pinion 146 when shifted from and into its terminal position, as will be readily understood. However, this rolling of the gear segment 144 on the pinion 146 will not in any way change any operating cycle for which the timer has been set prior to the start of the cycle. Thus, this rolling of the gear segment 144 on the pinion 146 will cause during a shift of the trigger from its terminal position into any set position a slight counterclockwise shift of the cam element 140 on the trigger (Fig. 1) which will continue as a clockwise shift of the same magnitude during the following shift of the trigger into its terminal position, so that the angular shift of the cam element will be canceled when the trigger returns to its terminal position and the time interval of operation then terminated will be exactly of the duration for which the timer was preset.

The formation of both the timing element 24 and the adjustable element 140 as cams is highly advantageous in that they may be designed to achieve most any desired movement of the trigger to its terminal position from the set position, whereby substantially uniform motion, approximate harmonic motion, variable motion and snap motion, for instance, may be obtained. Further, the pivotal arrangement of the cam element on the trigger and its angular adjustability thereon are instrumental in achieving an exceptionally wide range of timing interval variation with a minimum of bulk. Also, the instant arrangement of mounting the trigger 22 and pinion 146 on and in the single bearing 38 (Fig. 9) and providing the pivoted cam element on the trigger with a gear segment for direct mesh with the aforesaid pinion makes for structural simplicity of the timer as well as ready assembly of these parts with the rest of the timer. Moreover, the direct mesh of the gear segment of the pivoted cam element on the trigger with the pinion 146 and the journal support of the latter coaxially of the pivoted trigger support makes for accurate and immediate response of the cam element in its adjustment to any turn of the pinion at any time.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

What is claimed is:

l. A variable timer, comprising a pivoted operating member for controlling the operation of a device being timed by the timer, said operating member being turnable into and from a terminal position to terminate and Start, respectively, operating cycles of selectively timed duration; a gear segment pivoted on said operating member at a point remote from the pivot axis of the latter; a pinion in mesh with said gear segment and turnable about the pivot axis of said operating member; means for turning said pinion to adjust said gear segment relative to said operating member; a timing element normally urged in one direction into a starting position, and movable in the opposite direction, from its starting position through a distance varying with the adjustment of said gear segment, to coact with the latter and turn said operating member into its terminal position; a power drive for moving said timing element in said opposite direction at a predetermined rate; a clutch incorporated in said power drive; and means disengaging and reengaging said clutch in response to movement of said operating member into and from its terminal position, respectively.

2. A variable timer as set forth in claim 1, in which said gear segment has a contoured periphery forming a cam surface .with which said timing element coacts in turning said operating member into its terminal position.

3. A variable timer as set forth in claim 1, in which said power drive has an output shaft, and said timing clement is a cam carried by said output shaft.

4. A variable timer as set forth in claim 1, in which said power drive has an output shaft, said timing element is a cam carried by said output shaft, and said gear segment has a contoured periphery forming a cam surface with which said cam coacts in turning said operating member into its terminal position.

5. A variable timer as set forth in claim 1, in which said. gear segment has a contoured periphery forming a cam surface with which said timing element coacts' in turning said operating member into its terminal position,

said gear segment being adjustable to coact with said timing element in any position of the latter and turn said operating member into its terminal position for instanteneous termination of an operating interval of the timer at any time.

6. A variable timer, comprising a pivoted operating member for controlling the operation of a device being timed by the timer, said operating member being turnable into and from a terminal position to terminate and start, respectively, operating cycles of selectively timed duration; a gear segment pivoted on said operating member at a point remote from the pivot axis of the latter; a pinion in mesh with said gear segment and turnable about the pivot axis of said operating member; friction means to resist rotation of said pinion; manual means for turning said pinion to adjust said gear segment relative to said operating member; a timing element normally urged in one direction into a starting position, and movable in the opposite direction, from its starting position through a distance varying with the adjustment of said gear segment, to coact with the latter and turn said operating member into its terminal position; a power drive for moving said timing element in said opposite direction at a predetermned rate; a clutch incorporated in said power drive; and means disengaging and reengaging said clutch in response to movement of said operating member into and from its terminal position, respectively.

7. A variable timer for controlling the operating time of a device, comprising a bearing; an operating member connected to the device to be timed, said member being turnablymounted on said bearing externally thereof for movement into and from a terminal position to terminate and start, respectively, operating cycles of selectively timed duration; a gear segment pivoted on said operating member; a pinion in mesh with said gear segment and journalled in said bearing for rotation about the rotary axis of said operating member; spring means urging said pinion against said bearing frictionally to resist rotation of the former; manual means for turning said pinion to adjust said gear segment relative to said operating member; a timing element normally urged in one direction into a starting position, and movable in the opposite direction, from its starting position through a distance varying with the adjustment of said gear segment, to coact with the latter and turn said operating member into its terminal position; a power drive for moving said timing element in said opposite direction at a predetermined rate; a clutch incorporated in said power drive; and means disengaging. and reengaging said clutch on movement of said operating member into and from its terminal position, respectively.

References Cited in the file of this patent UNITED STATES PATENTS 2,609,044 Stanton Sept. 2, 1952

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