US3057973A - Switch actuating timer - Google Patents

Description

Oct. 9, 1962 c. J. GOODHOUSE SWITCH ACTUATING TIMER Filed April 11, 1960 2 Sheets-Sheet 1 INVENTOR.

Z/zamey Oct. 9, 1962 c. J. GOODHOUSE 3,057,973

SWITCH ACTUATING TIMER Filed April 11, 1960 2 Sheets-Sheet 2 IN VEN TOR.

gw/ J 540%04 54 W4 United States Patent 3,057,973 SWITCH ACTUATiNG TIMER Carl J. Goodhouse, Litchfield, Conn, assignor to General Time Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 11, 1960, Ser. No. 21,372 3 Claims. (Cl. 200-38) The present invention relates generally to electric switch actuating timing devices and concerns a timer particularly well suited for applications such as controlling a defrosting cycle in refrigerators.

The primary aim of the invention is to provide a novel switch actuating timer capable of reliably operating a switch through a short timed interval during a relatively much longer timing cycle. In this way, the timer accurately controls a cycle lasting but a few minutes, but occurring only once or twice a day.

It is an object of the invention to provide a timer of the above character which affords a particularly accurate timing cycle that can be easily and conveniently set to occur at an exactly selected time.

It is also an object of the invention to provide a timer as described above which snap-actuates common, inexpensive switch components to avoid arcing or fluttering of switch contacts, even though the timer operates the switch through only a small fractional part of the total timing cycle.

It is a further object to provide a reliable timer having the above characteristics which is exceptionally compact and quite inexpensive to manufacture.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:

FIGURE 1 is a top plan view with the cover removed of a switch actuating timer constructed in accordance with the present invention;

FIG. 2 is a side elevation of the timer shown in FIG. 1; and

FIGS. 3 and 4 are fragmentary views similar to FIG. 1, showing the operation of the timer in stop-motion form.

While the invention will be described in connection with a preferred embodiment, it will be understood that I do not intend to limit the invention to that embodiment. On the contrary, I intend to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Turning first to FIGS. 1 and 2 there is shown a switch actuating timer 15 embodying the invention adapted to operate an electric switch 16. The timer 15 includes a frame 17, which carries a switch base block 18 preferably formed of a dielectric material on which the components of the switch 16 are mounted.

The switch 16 includes a resilient contact arm 21 anchored by a terminal 22 to the base 18. The arm 21 is the movable member of the switch and carries a pair of opposed contacts 23, 24. When the arm 21 is swung upwardly, the contact 23 is urged into engagement with a contact 25 secured to a fixed terminal 26 mounted on the base 18. Lowering the arm 21 brings the contact 24 into engagement with a contact 27 secured to a fixed terminal 28 mounted on the base 18. Thus, lifting the arm 21 closes the contacts 23, 25 and opens the contacts 24, 27, while lowering the arm 21 opens the contacts 23, 25 and closes the contacts 24, 27. v

For moving the arm 21, the arm is provided with an operator in the form of a pin or rod 29. The operator pin 29 is preferably fixed between a pair of depending flange portions 30 formed integrally with the switch arm 21.

In accordance with the present invention, the switch operator 29 is biased against a latched control cam which is periodically, at regular predetermined moments, released and driven through a timed cycle wherein the cam operates the switch for a selected timed interval and then returns to its latched condition.

In the preferred embodiment, the control cam against which the operator 29 is biased takes on the form of a segmented. cam 31 loosely journalled on a post 32. The control cam 31 is provided with a drop-off portion 33 having one side 34 formed with a sloping cam surface. The drop-off portion 33 is proportioned so that when the operator 29 enters therein, the arm 21 will cause the switch 16 to operate. As the control cam 31 continues to rotate in a counterclockwise direction, the sloping surface 34 will cam the operator 29 out of the drop-off portion 33 and restore the switch to its original condition.

To latch the control cam 31 and thereby prevent it from continuous cyclical oscillation, a leaf spring 35 is secured to the timer frame adjacent the cam and the cam is biased in a counterclockwise direction by a tensioned helical spring 36 so that a ledge portion 37 of the cam abuts the end of the spring 35. The drop-off portion 33 of the control cam 31 is to the right of the operator 29 when the cam is biased against the spring 35 (see FIG. 1). Thus, it may be seen that with the control cam 31 latched, the switch 16 is maintained in an inoperative condition.

In order to disengage the spring 35 and free the cam 31 for cyclical operation, a trip-pin 38 is mounted on a driven gear wheel 39 so as to engage and lift the spring 35 out of engagement with the cam ledge portion 37 incident to rotation of the wheel 39. The gear wheel is secured to the post 32 coaxial with the cam 31 and is driven by a drive gear 40 through gears and pinions 41-44. The drive gear 40 is secured to an output shaft 45 driven by a synchronous timing motor 48 through speed reduction gears in a gear case 48a. The illustrated gear wheel 39 is provided with only one trip pin 38; however, it is understood that additional trip pins may be mounted on the wheel in order to vary the operating characteristics of the timer.

To drive the operating cam 31 through its cycle, a drive cam 46 is secured to the output shaft 45 adjacent the drive gear 40. The drive cam 46 rotates counterclockwise as seen in the drawings at a constant perdetennined rate when alternating current is supplied to the motor 48, and the cam is formed with a pair of drop-off steps 49, 50 connected by a spiral cam surface 51. The control cam 31 is provided with a cam follower in the form of an car 47 and is biased by the helical spring 36 so as to urge the car 47 toward the periphery of the drive cam 46.

During a cycle of operation, assuming the latch spring 35 to be clear of the ledge portion 37, it may be seen that as the drive cam 46 rotates in a counterclockwise direction, the car 47 is urged upwardly by the cam surface 51 so as to swing the control cam 31 in a clockwise direction. Upon further movement of the drive cam 46, the car 47 drops from the successive drop-off steps 49, 50 so that the control cam 31 jumps in a counterclockwise direction. In other words, the control cam 31 oscillates by slowly moving in a clockwise direction and then jumping back in a counterclockwise direction through two steps to its original position.

The control cam 31 is phased so that its drop-off portion 33 is adjacent the switch operator 29 when the cam has jumped to its first position with the ear 47 dropping from step 49 (see FIG. 3). Thus, the switch 16 is operated when the cam makes its first jump and is restored when the cam jumps the second time.

As a feature of the invention, the operator 29 is blocked from the drop-off portion 33 when the control cam 31 swings clockwise, thereby preventing operation of the 3 switch as the cam oscillates back to its latched position. In the illustrative embodiment, the return cycle blocking member takes the form of a blocking cam 52 loosely journalled coaxially with the control cam 31 on the post 32. The blocking cam 52 is spring biased in a counterclockwise direct-ion relative to the control cam 31 by spiral tensioned spring 52b and is formed so that the edge of a notch or relieved portion 53 registers with the dropoif portion 33 of the control cam 31 when an edge 54 of the cam is biased against the car 47.

To enable the operator 29 to enter the drop-01f portion 33 of the control cam 31, the blocking cam 52 has a pcriphery 52a which is on a somewhat greater radius than the periphery 31a of the control cam 31 (see FIG. 4). Thus, it may be seen that the outer edge of the drop-off portion 53 engages the operator pin 29 (see FIG. 1) and holds the blocking cam 52 against the bias of the spring 52b as the control cam 31 makes its first jump in a counterclockwise direction. Therefore, the operator is free to drop into the drop-off portion 33 so as to actuate the switch 16 (see FIG. 3).

As the control cam 31 continues its cycle and jumps into its second position, that is, when the ear 47 drops from the step 50, the cam surface 34 urges the operator 29 upwardly onto the periphery of the control cam, and the contact arm 21 is restored to its original position (see FIG. 4). The control cam 31 has a periphery 31b adjacent the sloping surface 34 with a radius slightly greater than the radius to the periphery 52a of the blocking cam 52. Thus, with the operator 29 riding on the periphery 31b of the control cam, the blocking cam 52 is free to rotate counterclockwise under the urging of the spring 52b to its initial position with the surface 54 abutting the eat 47.

To restore the control cam'31 to its initial latched position and thus complete the cycle, the drive cam 46 continues to rotate so that the spiral cam surface 51 returns the control cam 31 and the blocking cam 52 in a clockwise direction. This movement continues until the respective drop- 01f portions 33, 53 of the cams are slightly to the right of the operating pin 29 and the latch spring 35 snaps into latching engagement with the ledge 37. During this clockwise movement of the control cam the operator 29 rides across the drop-off portion '33 on the periphery 52a of the blocking cam and hence the switch 16 is not again operated upon the return oscillation of the cams.

To more readily understand the operation of the timer 15, a complete operating cycle of the timer will be briefly reviewed. Considering first FIG. 1, it will be appreciated that the switch cannot operate so long as the switch operator 29 rests on the periphery of the control cam 31 and the cam is latched by the spring 35. The contacts 23, 25 thus remain closed and the contacts 24, 27 open throughout the relatively long interval required to rotate the gear wheel 39 so as to bring the pin 38 into contact with the spring 35 to unlatch the control cam 31. In the illustrated embodiment the gear wheel 39 cycles once in twenty-four hours.

When the pin 38 lifts the spring 35 and releases the cam 31, the car 47 of the control cam is free to follow the drive cam 46 (see FIG. 1). As the ear 47 drops down the step 49 and the cam 31 makes its first counterclockwise jump, the corner of the relieved portion 53 of the blockingcam 52 engages the operator 29 and prevents the blocking cam from following the control cam 31.

Thus, the operator 29 is free to snap into the drop ofli portion 33 of the control cam to operate the switch 16 (see FIG. 3). As the drive cam 46 continues to rotate, the car 47 next drops 011 the step 50 causing the control cam 31 to jump again to the left and the operator 29 is carried upward to the periphery 31b of the control cam by the sloping surface 34 (see FIG. 4).

When the operator 29 rides up onto the periphery 31b of the control cam 31, the blocking cam 52 is released 4 to return to its position against the ear 47, thus closing the drop-off portion 33. Therefore, the switch is not again operated as the control cam is oscillated in the clockwise direction by the drive cam 46. Just before the control cam 31 reaches its extreme clockwise position and after the drop-off portion 33 has passed to the right of the operator 29, the spring member 35 engages the ledge portion 37 of the control cam thus completing the cycle.

In accordance with another aspect of the invention,

simple manual setting of the timer 15 is made possible The coil spring 55 is wound so that when the drive shaft 45 is rotated counterclockwise as seen in the drawings, the spring tends to contract and Wind more tightly on the adjacent sleeves 56, 57 so as to establish a positive driving connection from the motor 48 to the sleeves.

However, upon rotating the drive cam 46 and the drive gear 40 more rapidly than they are driven by the motor 48, the sleeve 57 tends to unwind and thus expand the coil spring 55 so as to permit overrunning of the cam and gear.

To set the timer 15, the drive cam 46 and drive gear 40 are manually rotated counterclockwise until a desired position is reached, and for the purpose, a setting knob 58 is provided. The setting knob 58 is preferably formed as a cap which fits loosely over the spring member 55. Depending from the knob 58 are a pair of lugs 59 which fit into slots (not shown) formed in the drive cam 46. The top of the setting knob 58, as well as the end of the post 32, extend through circular openings formed in a cover plate 60 secured to the frame 17 (see FIG. 2). The end of the knob 58 is provided with a slotted portion 61 permitting a screwdriver or similar tool to be easily inserted to turn the setting knob and thereby drive cam 46.

Since the drive-cam 46 and the drive gear 40 act together, rotating the drive cam also causes the drive gear to turn, transmitting movement through gears and pinions 41-44 to the gear 39. Thus, it may be seen that by turning the setting knob 58, both the drive cam 46 and the latch releasing pin 38 are positioned to set the timer for operation at a particular time. If desired, the end of the post 32 may be provided with an indicia line 62 (see FIG. 4) to indicate the adjusted position of the gear wheel 39 and its pin 38.

It is important to note that when the switch 16 is ope'rated, its operation is solely under the control of the cam 31 which moves rapidly, in spaced jumps, through its switch operating cycle. Thus, the switch contacts are moved quickly and positively into and out of contact and there is no opportunity for fluttering or arcing. It can also 'be seen that there is little friction or rubbing contact between the timer parts during most of the timing cycle. Only when the latch spring 35 is released and the switch 16, is being operated does the car 47 ride down the cam steps 49, 50. Wear and loading of the motor 48 is therefore minimized.

It will also be understood that the timer 15 is capable of reliably operating the switch 16 for an exactly determined, relatively brief interval at a particular predetermined time, during a relatively much longer timing cycle. However, since the switch 16 is snap-actuated, there is no danger of arcing between the contacts despite the very long timing cycle involved.

Those skilled in the art will also appreciate that the timer 15 can be constructed quite compactly and economically, since it utilizes components of standard types which can be easily formed by tools and techniques common to the art.

I claim as my invention:

1. A mechanism actuating timer comprising, in combination, a frame, a timing motor mounted on said frame, a drive cam coupled to said motor so as to be cyclically driven, a control cam journalled on said frame adjacent said drive cam, said control cam having a cam follower and being biased so that said follower is urged toward said drive cam, said drive cam being formed to oscillate said control cam when said follower rides on said cyclically driven dnive cam, a mechanism operator on said frame biased towards said control cam, said control cam being formed to operate said operator during each oscillation of said control cam, a latch on said frame for engaging said control cam at one point of its oscillation so as to lock the control cam from further oscillation, a latch release member movably mounted on said frame, and means coupling said motor and said member for driving the latter through a cycle wherein said member releases the latch and allows said control cam to be oscillated by said drive cam, the cycle of said member being an even multiple of the cycle of said drive cam.

2. A mechanism actuating timer comprising, in combination, a frame, a timing motor mounted on said frame, a drive cam coupled to said motor so as to be cyclically driven, a control cam journalled on said frame adjacent said drive cam, said control cam having a cam follower and being biased so that said follower is urged toward said drive cam, said drive cam being formed to oscillate said control cam when said follower rides on said cyclically driven drive cam, a mechanism operator on said frame biased towards said control cam, said control cam being formed to operate said operator during each oscillation of said control cam, a latch on said frame for engaging said control cam at one point of its oscillation so as to lock the control cam from further oscillation, a latch release member movably mounted on said frame,

means coupling said drive cam and said member for driving the latter through a cycle wherein said member releases the latch and allows said control cam to be oscillated by said drive cam, the cycle of said member being an even multiple of the cycle of said drive cam, and an overrunning clutch interposed between said drive cam and said motor so that the drive cam and the latch release member can be advanced and set for operation at a desired time.

3. A mechanism actuating timer comprising, in combination, a frame, a timing motor mounted on said frame, a drive cam coupled to said motor so as to be cyclically driven, a control cam journalled on said frame adjacent said drive cam, said control cam having a cam follower and being biased so that said follower is urged toward said drive cam, said drive cam being formed to oscillate said control cam when said follower rides on said cyclically driven drive cam, a mechanism operator on said frame biased towards said control cam, said control cam having a drop-off portion and an adjacent rise portion for operating said operator each time said control cam oscillates in one direction, means carried by said control cam for blocking said operator from said drop-off portion each time said control cam is oscillated in the opposite direction, a latch on said frame for engaging said control cam at one point of its oscillation so as to lock the control cam from further oscillation, a latch release member movably mounted on said frame, and means coupling said motor and said member for driving the latter through a cycle wherein said member releases the latch and allows said control cam to be oscillated by said drive cam, the cycle of said member being an even multiple of the cycle of said drive cam.

References Cited in the file of this patent UNITED STATES PATENTS 2,424,116 Puerner July 15, 1947 2,553,846 Clemens May 22, 1951 2,946,902 Hagan July 26, 1960

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