US2354368A - Interval timer - Google Patents

Description

y 1944- w. P. GALLAGHER 2,354,368

INTERVAL TIMER Filed Jan. 2, 1942 2 Sheets-Sheet 1 y 25, 1944' w. P. GALLAGHER v 2,354,368

INTERVAL TIMER Filed Jan. 2, 1942 2 Sheets-Sheet 2 lizvcn 1'01:-

M/i/lz'am f? Gafggyfzarf Q? 1m 4m 1 Patented July 25, 1944 IYNTERVAL mm William P. Gallagher, Chicago, Ill., assignor to International Register Company, Chicago, Ill., a corporation of Illinois Application January 2, 1942, Serial No. 425,397

15 Claims. (Cl; zoo-es I The present invention relates to electrical interval timers or time switches, and more particularly to such devices of the fixed interval type in which the switch moves to a predetermined position at a set time of the day or night, and remains in that position for a substantially fixed interval of time, whereupon the switch is then restored to its normal position.

These fixed interval timers are particularly suited for use as defrosting switches in electric refrigerators. In such use, the interval timer automatically interrupts the circuit of the refrigerator motor at a predetermined time of the night or day (usually at night), and maintains said circuit interrupted for a substantially fixed interval of sufiicient duration to defrost the refrigerator effectively, whereupon the timer again closes the motor circuit so that the refrigerator can resume normal operation. This time interval is generally of about three or four hours duration, and is preferably set to occur late at night or early in the morning, when the refrigerator is seldom being opened and closed. Once set to occur at this time, the automatic cycle of opening the motor circuit for a fixed interval will reoccur every night indefinitely without further attention.

One of the objects of the invention is to provide greatly simplified switch mechanism for automatically opening and closing the circuit. This switch mechanism obtains a snap opening of the contacts and a, snap closing of the contacts by an improved construction and arrange ment of movable switch elements whereinthe movable switch part moves through one path in effecting the snap opening, and moves through another path substantially at right angles thereto in effecting the snap closing.

Another object of the invention is to provide an improved manual control which can be set to render the interval timer non-functioning so that there will be no interruption of the motor circuit.

Another object of the invention is to provide an improved interval timer in which the defrosting interval can be readily adjusted to occur at a different time or times.

Other objects, advantages and features of the invention will appear from the following detail description of one preferred embodiment thereof. In the accompanying drawings illustrating such embodiment: v e

Figure l is a plan View or front elevational view of the entire interval timer;

Figure 2 is a horizontal view of the operating mechanism in its mounting on the sub-frame immediately below the cover,'corre sponding to a view taken on the plane of the line 22 of Figure 3; g e 1 I .Figure 3 is a longitudinal sectional view through the housing, showing some of the mechanism in section;

Figure 4 is a fragmentary elevational view of the one-way drive mechanism which is interposed. in the driving train between the electric motor and the switch actuator; and

Figures 5, 6, 7 and 8 are fragmentary views on a larger scale showing different positions of the switch parts. I

The mechanism is preferably enclosed within a housing comprising a casing l4 closed over by a cover plate (5 (Figure 3). A U-shaped subframe I6 is secured to the under side of the cover plate l5, and the various operating parts are assembled between this sub-frame and the cover plate. The end portions of said sub-frame are formed with tongues l1 which project upwardly through corresponding slots formed in the cover plate l5 (Figure 1). Screws lllpass down through the cover plate and thread into tapped holes in the bottom of the sub-frame l6 for releasably securing the latter to the cover plate. The electri cal conductors 2i enter the housing through the bottom wall ofthe casing l4 and have connection with suitable binding posts or terminals 24 projecting downwardly from an insulating panel 25 riveted to the underside of the sub-frame l6.

These conductors supply the alternating current which drives the synchronous motor. 21, and they also constitute the control circuit which is con trolled by the interval timer. Projecting from the. upper side of the cover plate [5 is a setting knob 28 and associated pointer 29 which rotate concentrically of a 24 hour dial 30 which is stamped or marked on the cover. This setting knob and pointer aremounted on the upper end of a time driven spindle or shaft 3| which carries the switch actuator. As hereinafter described in greater detail, rotation of the setting knob 28 and pointer 29 enables the interval timer to be properly synchronized with the time of day when the device is first cut into the circuit; and transposition of the P inter 29 to a diametrically opposite position with respect to the setting knob and actuator s'haftenables the defrosting interval to be shifted from day time to night time, or vice interval timer performing its intended function of defrosting the refrigerator periodically at the desired interval, and, which when swung to the upper end of the slot, renders the switch of the interval timer non-functioning, but without stopping the synchronous motor 21 and the switch actuator driven thereby.

Referring now in detail to the construction, the electric motor 21 which drives the interval timer is preferably a conventional synchronous alternating current motor of the type commonly employed for driving electric clocks, although it will be understood that other time controlled or time driven mechanism can be employed in lieu of such electric motor. The motor unit 21 includes a gear reduction housing 31 enclosing suitable reduction gearing, this housing being secured by screws 38 to the horizontal portion of the subframe IS. A shaft 39 at the outer end of this reduction gearing mounts a small spur pinion 4| on the under or back side of the sub-frame I6. This pinion meshes with a large spur gear 42 which is part of a one-way drive mechanism rotatably mounted on a stationary bearing stud 43. The upper end of this bearing stud 43 is rigidly staked in a raised supporting lug 44 which is punched upwardly or forwardly from the body of the sub-frame IS. The large gear 42 is adapted to transmit a drive to a pinion 46 coaxial therewith through the one-way drive device, indicated in its entirety at 41. This one-way drive device enables the interval timer to be properly set without transmitting reverse motion to 'the switch actuator, and without transmitting any such setting motion to the electric motor 21. The details of this one-way drive device are fully disclosed in my copending application Serial No. 417,614, filed November 3, 1941, and hence I shall only make a brief description of the construction in this application. The driving gear 42 is formed with an annular series of driving shoulders 5| projecting rearwardly from the body of the gear. As shown in Figure 4, these shoulders are preferably formed by punching tongues rearwardly from the gear, the free ends of the tongues facing in the normal, clockwise direction of rotation of the driving gear 42. The driven element of this one-way drive 'device is in the form of a spider 54 comprising a hub portion from which radiates a plurality of evenly spaced spring arms'56. These spring arms are preferably curved in the approximate S-formation shown so as to be of longer length for increased resiliency. The central portion of the spider is spaced slightly from the drive gear 42, but the tip ends of the spider are sloped forwardly so as to bear constantly against the surface of the gear and to be engaged by the driv-r ing shoulders 5|. With reference to the mounting of this one-way drive device, the pinion 46 is formed with an integral bearing extension or hub 59, and this gear and hub unit is rotatably mounted on the stationary bearing stud 43. The drive gear 42 is mounted on the bearing hub 59 so as to be capable of free rotation thereon. The spider 54 is mounted on an outer reduced extension 5% of the bearing hub 59; the shoulder at the inner end of the outer extension maintaining the hub of the spider spaced away from the surface of the drive gear 42. Splayed or other like driving surfaces 590 on the outer bearing extension 5% engage corresponding driving surfaces formed in the hub of the spider 54 so that'a keyed relation is always maintained between the spider 54 and pinion 46.v The bearing hub 59 of gear 42 andthe bearing hub of the spider 54 are held relation to each other.

against endwise displacement off the end of the stationary bearing stud 43 by a U-shaped retainer clip 6| which snaps into an annular groove formed in the end of the stud 43.

It will be apparent that the small spur pinion 4| driven by the electric motor 21 will impart a continuous, time driven rotation to the large driving gear 42 at all times. In Figure 4, this direction of rotation is clockwise, such rotation operating through the gears 46 and 63 to impart clockwise rotation to the time driven shaft 3|, pointer 29 and knob 28, as viewed from the front of the timer unit. It will be noted that in this clockwise rotation of the driving gear 42, the driving shoulders 5| transmit the driving torque to the tip ends 56 of the spider 54. There are preferably a relatively large number of driving shoulders 5| and a relatively large number of driven shoulders 56, and the number of shouldersin one series is in prime relation to the number of shoulders in the other series. For example, in the preferred construction shown, there are nine driving shoulders 5| and eight driven shoulders 56, these two numbers being in prime By virtue of this relation, only one driving shoulder and one driven shoulder will be engaging at any particular time. Upon a very small advancing movement of the spider relatively to the drive gear, drive relation is immediately transferred to another drive shoulder and driven shoulder (the next in rearward sequence). The gear reduction from the armature of the electric motor to the pinion 4| is of such design or of such magnitude that the motor cannot be driven in the reverse direction by any manual force capable of being exerted on the setting knob 28. It will thus be seen that by virtue of this one-way driving relation, the gear 42 positively drives the spider 54 in a clockwise direction, and also enables the spider to be advanced in a forward or clockwise direction relatively to the gear, but does not permit the spider to be rotated backwardly relatively to the gear.

The gear ratio of the driving train is such that the gear 63 and time driven spindle 3| make exactly one complete revolution every 24 hours The spindle 3| has a reduced rear end which is journaled in the sub-frame l6, and has a reduced upper portion which is journaled in the cover plate I5, The spur gear 63 is riveted to a flange 3|a projecting outwardly from the rear portion of the shaft-3|. The setting knob 28 screws over a right hand thread formed on the reduced front end 3|b of the shaft 3|. Two diametrically opposite splayed surfaces 3|c are formed at the inner end of the reduced portion 3|b for receiving corresponding driving surfaces formed in the central portion of the pointer 29. The setting knob 28 screws inwardly along the thread and clamps the pointer 29 to the inner ends of the splayed surfaces 3|c. By removing the setting knob 28, the pointer 28 can be released from the splayed surfaces, and then transposed to a diametrically opposite position, where it is again secured to the shaft 3| by the setting knob 28. This transposition of 180 results in a 12 hour shift in the indication afforded on the dial 30, as a result of which the defrosting interval can be shifted from an a. In. time to a p. In. time, or vice versa. The right hand thread 3|b over which the setting knob 28 screws enables the setting knob to advance the shaft 3| in a right hand or clockwise direction, but merely results in the knob unscrewing from the shaft if it is attempted to adjust the shaft in a counterclockwise direction. Such counterclockwise direction would be likely to injure the switch mechanism.

The switch mechanism is actuated by an actuating cam 66 which is secured fast to the splayed forward end of a hub portion ale on the shaft. This cam is composed of insulating material, such as a linen base Bakelite punch stock. Formed in the periphery of this cam is an arouate gap or notch 68 which is proportioned in' length to give the desired fixed interval of time for defrosting the refrigerator. In most instances, a defrosting interval of approximately four hours is desired, although it will be under- I stood that longer or shorter intervals may be easily obtained by merely substituting actuating cams having longer or shorter notches 68, As clearly shown in Figure 5, the leading edge 69 of this notch 68 is formed relatively sharp, and is undercut or recessed at 1.0 to effect snap opening of the switch. The trailing end H of the notch is slightly rounded, and is also preferably recessed or undercut at 12.

The switch comprises a stationary contact and a movable contact 16, the latter responding to the cam 66. The stationary contact 15 is secured to the forward portion of a rigid terminal bracket 15a which has its rear end anchored to the insulating panel 25, and carries one of the terminal screws 24. The movable contact 16 is secured to one end of a leaf spring blade element 16a which is capable of switch opening motion in one path and switch closing motion in another path, substantially at right angles thereto. accommodate these two motions, the blade 16a is formed with a substantially circular resilient loop 16b terminating in an attachment portion 16c which projects approximately at right angles to the main length of the blade element. The attachment portion 160 is riveted to a rigid terminal bracket H, which has its rear end anchored to the insulating panel 25, and carries one of the terminal screws 24. Riveted to the flexing span of the blade element, at a point intermediate the contact 16 and the bowed portion 16b is a clip or bracket 1.8 formed with a right angle flange or shoulder 19 at one end. This shoulder 19 constitutes the rider element of the movable blade assembly which. rides on the time driven cam 66. The inherent resiliency in the spring blade 16a tends to bias the switch toward the open circuit position shown in Figure 6.

Also cooperating with the rider shoulder 19 is a manual cam 8i which responds to the shifting of the control pin 34 in the slot 33. Said manual actuated cam 8| is also composed of insulating material, preferably of the same composition as the cam disc 66, and is formed with a cam slope 8ia terminating in a detent notch Mb. The cam is riveted to the rear arm 82a of a rotatable bracket 82. This rear arm of the bracket is formed with a bearing hole which engages over the shaft 3!, so that the bracket 82 rotates about the axis of the shaft. The bracket is formed with a forwardly extending web portion which terminates in a front arm or segment 820. This segmental portion lies immediately under the arcuate slot 33 in the cover plate l5, and the control pin 34 is fixedly anchored in said segmental portion 820. When the control pin 34 is oscillated down to the defrost end of the slot 33 the cam 8| assumes the inoperative or non-functional position shown in dotted lines in Figure 8. When the control pin 34 is swung up to the ofi" end of the slot 33 the cam M is oscillated into the switch closing position illustrated in full lines in Figure 8, such motion of the cam acting through the cam slope 8 i a against the movable contact shoulder 19 to fiex the movable contact into circuit closing position. In this position, the shoulder T9 snaps into the detent notch Bib of the cam for establishing a releasable detent engagement, holding the control pin 34 in its off position.

Referring now to the operation of the timer, Figure 5 illustrates the normal closed circuit position of the switch. In this position, the solid periphery of the cam 66 bears against the rider 19 of the movable blade element 16a, thereby retaining the movable contact I6 pressed against the stationary contact 15. Because of the spring resiliency of the blade element 16a, and the fact that the rider member 19 is mounted thereon substantially intermediate the ends of the blade element, the transverse resiliency of the blade is utilized to hold the contacts together under spring pressure. Figure 6 illustrates the switch opening operation with occurs as soon as the leading shoulder 69 of the notch 68 rotates past the rider shoulder 19. The blade element 16a immediately flexes toward the right, producing a snap separation of the contacts '15 and 15. The switch remains in this open circuit position for the fixed interval predetermined by the length of the notch 68. Near the end of this interval, the rounded trailing shoulder H of the notch engages the forward surface of the rider member 19 and starts exerting pressure on the blade element 16a in a direction approximately along the length of the blade element. With the continued rotation of the actuator disc 56, the shoulder "H continues to force the blade element ma substantially in a rearward direction, as illustrated in full lines in Figure 7. The resiliency inherent in the relatively large loop portion 161) permits this endwise rectilinear motion of the blade element. With the continued rotation of the actuator disc, the trailing shoulder H finally rides off the edge of the shoulder member 19, thereby permitting the blade element 16a to snap forwardly again under the spring energy stored in the loop portion 16b. In snapping forwardly under this spring energy, the riding shoulder 79 follows the circular contour of the disc 66. This guides the return motion of the movable contact 16 in a general. direction toward the stationary contact 15, so that the two contacts are brought together with a sidewise motion, the movable contact sliding across the face of the stationary contact substantially from the side thereof. This results in a wiping of the contact surfaces at the time that they reengage. In the final position indicated in dotted lines, the switch is back in the normal closed circuit position shown in Figure 5. The engagement of the contacts in this switch closing operation ocours with a snap motion, so that all pitting and arcing of slowly engaging contacts is avoided. In snapping back into this closed circuit position, the movable blade structure moves 'into a wedging relation wherein the movable contact 16 is wedged against the stationary contact '15 and the rider shoulder 19 is wedged against the periphery of the disc 66, which holds the two contacts together under resilient pressure, as described above in connection with Figure 5.

It will be noted that the movable contact or movable blade element has motion through two paths, substantially at right angles to each other.

In the switch opening operation, the contact 16 moves along the path indicated at X in Figure 6, such being in a plane substantially at right angles to the plane of interengaging faces of the contacts. In the switch closing operation, the movable contact 76 moves along a path indicated approximately by the arrow Y in Figure '7, which is approximately parallel to the plane of the interengaging faces of the contacts. This operating relation enables the snap separation and the snap reengagement of the contacts to be obtained with a relatively simple structure and simple operating motion.

Figure 8 illustrates the manually actuated cam 81 swung into switch closing position, when it is desired to discontinue the automatic defrosting cycle. This exerts camming pressure on the rider shoulder 9 for swinging the movable contact 16 into engagement with the stationary contact 15. The yieldable detent engagement of the rider member 19 in the notch 8lb resiliently holds the manual control in this position until the control pin 34 is swung back to the lower end of the slot 3-3. This manual control mechanism enables the interval timer to be placed in a non-operative condition with the switch 15-16 held closed, whereby the refrigerator will continue in its normal operation Without being interrupted by any defrosting interval. Such may b a desirable condition temporarily, in order to meet brief peak load requirements, or to insure operation after current failures etc. This nonoperative condition of the interval timer is obtained without stopping the synchronous motor 21, and hence the timer is not thrown out of timed step by the erformance of the manual control.

When the interval timer is first cut into circuit in its capacity of controlling the refrigerator motor, the knob 28 is rotated in a clockwise direction to place the pointer 29 in registration with that point of the dial 38 corresponding to the hour of the night or day when the refrigerator is first started. The one-way drive device 81, together with the right hand thread 3lb on the shaft 3|, enable the knob, pointer and cam 66 to be rotated into this synchronized position by clockwise rotation, but prevent counterclockwise rotation, which might cause injurious jamming between the cam drop-off shoulder 69 and the rider lug 19. If it is desired to transpose the defrosting interval from an a. m. time to a p. In. time, or vice versa, it is only necessary to transpose the pointer from one position on the driving surfaces 3 lo to the diametrically opposite position permitted by these surfaces, and to then reset the time indication of the pointer over the dial 30 so that it indicates the true clock time of that moment. This transposition merely changes the angular relation between the pointer 29 and the notch 68 corresponding to an interval of twelve hours. If a smaller shift in the defrosting time is desired, such can be accomplished by adjustments made through the knob 28, even though such adjustments may introduce a slight error of reading in the time indication given over the dial 30.

While I have illustrated and described what I regard to be the preferred embodiment of my invention, nevertheless it will be understood that such is merely exemplary and that numerous modifications and rearrangements may be made therein without departing from the essence of the invention.

I claim:

1. In a switch, the combination of a pair of cooperating contacts, one movable relatively to the other, and switch actuating mechanism effecting snap opening of said switch by motion of said movable contact along one path, and effecting snap closing of said switch by motion of said movable contact along another path.

2. In a switch, the combination of a relatively stationary contact, a contact spring carryin a movable contact adapted to engage said relatively stationary contact, said spring being capable of transverse motion and endwise motion, said spring being biased transversely so as to tend to separate said contacts, and rotary switch actuating means operative to open the switch by permitting such transverse separation of the contacts, and operative to close said switch by causing said spring to move endwise and transversely.

3. In a switch, the combination of a relatively stationary contact, a contact spring anchored at one end and carrying a movable contact at its other end adapted to engage with said relatively stationary contact, a resilient loop portion formed in said contact spring permitting transverse motion and endwise motion of the contact carrying end of said spring, and a switch actuating cam governing transverse motion of said contact spring in the opening of the switch and governing endwise motion of the spring in the closing of the switch.

4. In a switch, the combination of a relatively stationary contact, a contact spring anchored at one end and carrying a movable contact at its free end, a resilient loop portion formed in said contact spring intermediate its ends, said loop portion permitting transverse motion and endwise motion of said free end, and a time-driven rotary cam comprising a notch permitting transverse motion of said contact spring in the opening of the switch, and comprising a shoulder for causing endwise motion of said spring in the closing of said switch.

5. In a fixed interval timer, the combination of a relatively stationary contact, a resilient contact spring anchored at one end and carrying a movable contact at its free end, a resilient loop portion formed in said contact sprin intermediate its ends, said loop portion permitting transverse motion and endwise motion of the free end of said spring, a rider shoulder projecting from said spring, a time driven rotary cam against which said rider bears, a notch in said cam permitting transverse motion of said contact spring in the switch opening operation, and a shoulder on said cam adapted to engage said rider shoulder and shift said spring endwise, and to thereupon release said spring for return endwise motion into engagement with said relatively stationary contact in the switch closing operation.

6. In an interval timer, the combination of a pair of cooperating switch contacts, one movable relatively to the other, switch actuating mechanism comprising a. time driven member together with means cooperating therewith for efiecting separation of said contacts by motion of said movable contact along one path, and for effecting engagement of said contacts by motion Of said movable contact along another path, and separate control means operative to hold said contacts engaged independently of said switch actuating mechanism.

7. In a switch, the combination of a relatively stationary contact, a cooperating relatively movable contact, means mounting said movable contact for movement in a direction substantially at right angles to said stationary contact and for movement in a direction substantially parallel to said stationary contact, automatic switch actuating means for causing movement of said movable contact in one direction for closing the switch and in the other direction for opening the switch, and manual control means for holding said contacts in engagement independently of said automatic switch actuatin mechanism.

8. In a switch, the combination of a pair of cooperating contacts, one movable relatively to the other, a single time driven switch actuator operative by unidirectional rotation to efiect opening of said switch by motion of said movable contact along one path, and to eiiect closing of said switch by motion of said movable contact along another path, an electric motor for driving said switch actuator, adjusting means for adjusting said switch actuator relatively to said electric motor, and a one-way drive device associated with said switch actuator to restrict such adjustment to motion in one direction.

9. In a fixed interval timer of the class described, the combination of a switch comprising a pair of cooperating switch contacts, one movable relatively to the other, a resilient contact spring anchored at one end and carrying said movable contact at its free end, a resilient loop portion formed in said contact spring intermediate its ends, said loop portion permitting transverse motion and endwise motion of the free end of said spring, a time driven rotary cam cooperating with said contact spring, said cam permitting transverse motion of said spring in the opening of said switch, and causing endwise motion of said spring in the closing of said switch, time indicating means, an electric motor driving said time driven rotary cam and said time indicating means, adjusting means enabling relative angular adjustment to be effected between said time driven rotary cam and said time indicating means, a one-way drive device interposed in the driving train between said electric motor and said time driven rotary cam, whereby rotational adjustment of said cam can only be performed in one direction, and manual control means for holding said contacts in closed circuit position independently of the operation of said time driven rotary cam.

10. In a switch, a relatively stationary contact, a spring, a point of anchorage for one end of said spring permitting lateral and endwise movement of said spring, a movable contact carried by said spring adjacent to the other end thereof, said spring having a normal bias tending to separate said contacts, a rotary cam adapted to bear against said spring intermediate its ends to hold said contacts closed, a notch in said cam adapted to permit lateral fiexure of said spring for opening said contacts, and a shoulder on said cam for imparting endwise movement to said spring in the operation of closing said contacts.

11. In a switch, a relatively stationary contact, a spring, a point of anchorage for one end of said spring permitting lateral and endwise movement of said spring, a movable contact carried by said spring adjacent to the other end thereof, said spring having a normal bias tending to separate said contacts, a rotary cam adapted to bear against said spring intermediate its ends to hold said contacts closed, a notch in said cam adapted to permit lateral flexure of said spring for opening said contacts, a shoulder on said cam for imparting endwise movement to said spring in the operation of closing said contacts, and separate control means operative to hold said contacts engaged independently of said rotary cam.

12. In a switch, the combination of a pair of cooperating contacts, one movable relatively to the other, switch actuating mechanism eiTecting snap opening of said switch by motion of said movable contact along one path, and efiecting snap closing of said switch by motion of said movable contact along another path, and separate control means operative to hold said contacts engaged independently of said switch actuating mechanism.

13. In a switch, the combination oi: a pair of cooperating contacts, one movable relatively to the other, and switch actuating mechanism comprising a rotary member disposed on the back side of said movable contact in position for forcing said movable contact into engagement with said stationary contact, and also comprising means for effecting separation of said contacts by motion of said movable contact along one path, and for efiecting engagement of said contacts by motion of said movable contact along another path.

14. In a switch, the combination of a pair of cooperating stationary and movable contacts, means mounting said movable contacts for motion along separate paths in the opening and closing of said switch, rotary switch actuating means disposed in position for forcing said movable contact into engagement with said stationary contact, means associated with said r0- tary switch actuating means for causing said movable contact to move along one path, and means associated with said rotary switch actuating means causing said movable contact to move along another of the aforesaid paths.

15. In a switch, the combination of a pair of cooperating stationary and; movable contacts, means mounting said movable contacts for motion along separate paths in the opening and closing of said switch, rotary switch actuating means disposed in position to press said movable contact into engagement with said stationary contact, a notch associated with said rotary switch actuating means for causing said movable contact to move along one of the aforesaid paths, a shoulder associated with said rotary switch actuating means for causing said movable contact to move along another of the aforesaid paths, and separate control means operative to hold said contacts engaged independently of said rotary switch actuating means.

WILLIAM P. GALLAGHER.

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