US3020772A - goodhouse - Google Patents

Description

Feb. 13, 1962 c. J. GOODHOUSE SWITCH AC'TUAT ING TIMER 2 Sheets-Sheet 1 Filed Feb. 24. 1959 INVENTOR. v far/ J iaaa iaz/se, BY

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Feb. 13, 1962 c. J. GOODHOUSE SWITCH ACTUATING TIMER Filed Feb. 24. 1959 2/ as 32 a 34 2 sheets sheet 2 INVENTOR.

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United States Patent Ofilicc 3,020,772 Patented Feb. 13, 1962 3,020,772 SWITCH AKITUATING TIMER Carl J. Goodhouse, Litchfield, Conn, assignor to Genernl Time Corporation, New York, N.Y., a corporaticn of Delaware Filed Feb. 24, 1959, Ser. No. 794,975

' 4 Claims. (Cl. 74-54) The present invention relates generally to electric switch actuating timing devices and concerns a timer particularly well suited for controlling a defrosting cycle in refrigerators.

The primary object 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 can effectively control a refrigerator defrosting cycle lasting but a few minutes but which occurs only once or twice a day.

it is also an object of the invention to provide a timer as described above which snap-actuates common, inex pensive switch components to avoidarcinglor 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 section of a switch actuating timer con structed in accordance with the present invention;

FIG. 2 is a section taken approximately along the line 22 of FIG. 1; and

FIGS. 3, 4 and 5 are fragmentary views similar to FIG. 1, showing in stop-motion form, the operation of the timer.

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 embodying the invention which is effective to operate an electric switch 16. The timer 15 includes a frame 17 on which is rigidly mounted a switch housing 18, preferably formed of a dielectric material, that supports the components of the switch 16.

The switch includes a pair of resilient contact arms 21, 22 anchored by terminals 23, 24 to the housing 18. The arm 21 is the movable member of the switch and it carries a pair of opposed contacts 25, 26. When the arm 21 is swung upwardly, the contact 25 is urged into engagement with a contact 27 carried by the arm 22.

Lowering the arm 21 brings the contact 26 into engagement with a contact 28 which is carried by a fixed-term nal 29 mounted in the housing 18. Thus, lifting the arm 21 closes the contacts 25, 27 and opens the contacts 26, 28, while lowering the arm 21 opens the contacts 25, 26 and closes the contacts 26, 28.

To prevent the contacts 25, 27 from remaining in engagement when the arm 21 is lowered, a lug 31, preferably formed as an integral portion of the housing 18, engages the end of the arm 22 when the arm 21 is lowered (see FIG. 4) and positively holds the contacts 25, 27 apart.

For moving the arm 21, the arm is provided with an operator 32 in'the form of a pin or rod. The operator pin is secured to the arm 21 by being fixed between a pair of depending flange portions 33 formed integrally with the switch arm.

In accordance with the present invention, the operator 32 is biased against a cyclically driven control cam having a drop-off portion, and a timing member is provided which blocks the operator from the cam drop-off portion. The timing member is driven through a cycle whose duration is a multiple of the control cam cycle and is formed to periodically free the operator for operation by the control cam.

In the illustrated embodiment, the operator 32 is urged against a control cam 35 by mounting the contact arm 21 so that its inherent resilience tends to swing the operator 32 against the control cam. The control cam 35 is provided with a drop-oil portion 36 having one side 37 formed as a sloping cam surface.

In the preferred form of the invention, the control cam 35 is loosely journaled on a shaft 41 and is driven in an oscillating cycle by a drive cam 42. The drive cam 42 is secured to an output shaft 43 of a synchronous timing motor 44 which drives the shaft 43 through speed reduction gears in a gear case 45. The drive cam 42 rotates counterclockwise, as seen in the drawings, at a constant predetermined rate when alternating cur-rent is supplied to the motor 44.

To enable the drive cam 42 to oscillate the control cam 35 through its cycle, the cam 35 is provided with a cam follower in the form of a pin 46 and is biased by a tensioned spring 47 so as to urge the pin 46 against the periphery of the drive cam 42. The drive cam is formed with a pair of drop-off steps 51, 52 connected by a spiral cam surface 53. It may thus be seen that as the drive cam 42 rotates in a counterclockwise direction, the pin 52 is urged to the left by the cam surface 53 so as to swing the control cam 35 in a clockwise direction against the urging of the spring 47. Upon further movement of the drive cam 42, the pin 46 drops from the successive drop-off steps 51, 52 so that the control cam 35 jumps in a counterclockwise direction under the urging of the spring 47 to a first position as the pin 46 drops from the step 51, and then to a second position as the pin drops from the step 52. In other words, the control cam 35 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 35 is phased so that its drop-off portion 36 is adjacent the switch operator 32 when the cam has jumped to its first position with the pin 46 dropping from the step 51 (see FIG. 4).

In the illustrated embodiment, the member which blocks the operator 32 from the drop-off portion 36 of the control cam takes the form of a timing cam 60 mounted coaxially with the control cam 35. The timing cam is provided with a relieved peripheral or drop-off portion 61 and is secured to the shaft 41. The cam 60 is rotated by the motor 44 through a pinion 62 carried by the output shaft 43 and a gear 63 mounted on the shaft 41 (see FIG. 2). Thus, the timing motor 44 cycles the timing cam 60 in a clockwise direction while driving the control cam 35 through its oscillating cycle.

The cycle of the timing cam 60 has a duration which is a multiple of the cycling interval of the control cam 35. In the illustrated embodiment, the control can 35 cycles, that is, makes a complete oscillation, six times while the timing cam 60 cycles once, that is, makes one complete revolution.

To more readily understand the operation of the timer 15, a complete operating cycle of the timer will be reviewed. Considering first FIG. 1, it will be appreciated that so long as the switch operator 32 rests on the periphery of the timing cam 60, the oscillating control cam 35 cannot operate the switch 16. The contacts 25, 27 thus remain closed and the contacts 26, 28 open throughout the relatively long time interval required to rotate the 3 timing cam 6t) so as to bring the relieved portion 61 adjacent the operator 32. In the preferred embodiment, the timing member 66 cycles once every twelve hours.

When the timing cam 69 approaches the end of a cycle and the relieved portion 61 is brought adjacent the operator 32, as shown in FIG. 3, it will be seen that the operator 32 rests solely on the control cam 35. As the control cam 35 cycles, the pin 46 drops from the step 51, see FIG. 4, and the drop-d portions 36 and 61 are brought into alinement adjacent the operator 32. Because of the resilience in the contact arm 21, the arm swings downwardly to open the contacts 25, 27 and close the contacts 26, 2.8.

As the control cam 35 continues its cycle and jumps into its second position, that is, when the pin 46 drops from the step 52, the cam surface 37 urges the operator upwardly onto the periphery of the control cam, and the contact arm 21 is restored to its original position with the contacts 25, '7 closed and the contacts 26, 23 opened. Soon thereafter, the timing member 69, continuing its steady rotation, moves sutiiciently far to carry the relieved portion 61 away from the operator 32 so that subsequent cycles of the control cam 35 are ineffective to operate the switch 16 until the timing cam 69 again completes its full cycle.

It is important to note that when the switch 16 is operated, its operation is solely under the control of the cam 35 which moves quite rapidly, in spaced jumps, when operating the switch. Thus, the switch contacts are moved quickly and positively into and out of contact and there is no opportunity for fluttering or arcing.

The length of time during which the switch is operated is determined by the spacing between the steps 51, 52 on the drive cam 42, that is, by the length of a ledge 65 which connects the steps. In the illustrated embodiment, the ledge 65 is sufiiciently long to hold the switch 16 operated for the period of three minutes. By selecting an appropriately proportioned drive cam 42, this time interval can be adjusted quite accurately.

It can now be understood that the timer is capable of reliably operating the switch 16 for an exactly determined relatively brief interval, three minutes in the illustrated embodiment, once during a relatively much longer timing cycle, twelve hours in the illustrated example. However, since the switch 16 is snap-actuated, it can be seen that 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 timing motor, a control cam, means for intermittently stepping said control cam, said means being powered by said motor so that the control cam is stepped through repeating cycles, said cam having a drop-off portion, a mechanism operator biased against said cam and being operated when said drop-off portion is alined therewith at one of said intermediate steps, a timing member for blocking said operator from said drop-0d portion, said timing member being driven by said motor through a cycle whose duration is a multiple of said control cam cycle, and said member having a relieved portion which periodically frees said operator for operation under the control of said control cam.

2. A mechanism actuating timer comprising, in combination, a timing motor, a timing cam coupled to said motor for rotation through a repeating cycle, a jump cam positioned adjacent said timing cam, a movable mechanism operator biased against the peripheries of said cams, each of said cams having drop-off portions permitting operation of said operator when said portions are each alined adjacent the operator, means powered by said motor for cycling said jump cam at a speed which is a multiple of said timing cam cycle, said means being ehfective to jump said jump cam during its cycle with a snap action into and out of the position at which the drop-off portion of the jump cam is adjacent said operator, said cams being phased so that once during each timing cam cycle said drop-off portions coincide adjacent the operator and the mechanism operator is operated.

3. A mechanism actuating timer comprising, in combination, a timing motor, a timing cam coupled to said motor for movement of said cam through repeating cycles, a control cam positioned adjacent said timing cam, a movable mechanism operator biased against said cams at a fixed location, each of said cams having drop-01f portions permitting operation of said operator when the portions are alined at said location, means powered by said timing motor for oscillating said control cam through repeating cycles, said means causing the control cam to jump to first and second positions during its cycle, said cams being phased so that every time the timing cam dropoil portion reaches said location the control cam first jumps to its first position disposing its drop-off portion at said location, thus operating said mechanism operator, and then the control cam jumps to its second position to restore the mechanism operator.

4. A mechanism actuatin timer comprising, in combination, a timing motor, a circular timing cam coupled to said motor for rotation of said cam through repeating cycles, a control cam positioned adjacent said timing cam and journaled coaxially therewith, a movable mechanism operator biased against the peripheries of said cams at a fixed location, each of said cams having drop-off portions permitting operation of said operator when the portions are alined at said location, means for resiliently urging said control cam in one direction, a drive cam coupled to said timing motor for oscillating said control cam through repeating cycles, the cycle of said timing cam being a multiple of the cycle of said control cam, said drive cam having spaced drop-off steps causing the resiliently urged control cam to jump to first and second positions during its cycle, said cams being phased so that every time the timing cam drop-off portion reaches said location the control cam first jumps to its first position disposing its drop-0d portion at said location, thus operating said mechanism operator, and then the control cam jumps to its second position to restore the mechanism operator.

References Cited in the file of this patent UNITED STATES PATENTS 2,424,116 Puerner July 15, 1947 2,925,478 Yamasaki Feb. 16, 1960

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