US2614395A - Defroster control - Google Patents

Description

Oct. 21, 1952 H. 5. KING DEFROSTER CONTROL 5 Sheets-Sheet 1 Filed July 29, 1948 hily, i

MI I ENTOE QMVZ Oct. 21, 1952 H s K|NG DEFROSTER common 3 Sheets-Sheet 2 Filed July 29, 1948 Oct. 21, 1952 H. 5. KING" 2,614,395

DEFROSTER CONTROL Filed July 29, 1948 3 Sheets-Sheet 3 IN V5 IV 7' 0E HHEOAD 5. K/IVG Patented Oct. 21, 1952 DEFROSTER CONTRQL Harold S. King, Elkhart, Ind., assignor to Penn Controls, Inc., a corporation of Indiana Application July 29, 1948, Serial No. 41,282

13 Claims. (Cl. 62-4) This invention relates to adefroster control of the type wherein a timer operates a by-pass valve for the expansion valve of an evaporator, and a switch at the same time closes for insuring operation of the refrigerant compressor motor when the timer calls for a defrosting operation, hot refrigerant then being pumped through the evaporator for melting the frost therefrom.

One object of the inventioniis to provide a timer actuated defrosting valve wherein a comparatively heavily loaded spring-closed valve maybe opened by a relatively weak motor, such as an electric clock motor.

More particularly it is an object of the present invention to provide a cam moved spring- .loaded lever in which the'spring can be gradually A further object is to provide a control switch in connection with the timer motor and actuated thereby, which shunts the usual automatic switch provided for the refrigerant compressor motor and insures operation of the refrigerant compressor during the defrosting period, re-

gardless of whether or not the normal control switch 'is calling for refrigeration.

-With these and other objects in view, my invention consists in the construction, arrangement, and combination of the various parts of my device whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawings, wherein:

"Figure 1 is a front elevation of a defroster control embodying my invention and showing it in a normal position, that is, when not calling for a defrosting operation, a refrigerant system and a wiring circuit for the refrigerant compressor motor thereof being shown in conjunction with this figure- Figure 2 is a similar view omitting the diagrammatic showing and illustrating the defroster control tripped to the operative position.

Figure 3 is a view similar to a portion of Figand ure 2 showing the parts in the position assumed following the conclusionof the defrosting period.

Figure 4 is an end elevation of the control'as viewed from the right hand endof Figure 1;

Figures 5 and 6 are sectional views on the lines 5-5 and 66 respectively, of Figure 4.

On the accompanying drawings I have used the reference numeral In to indicate a mounting plate, and I2 a flange extending therefrom on which a by-pass valve V is located; The valve V has an inlet M, an outlet [6, a valve seat 18, and a valve disc 20. s

Extending from the disc is a stem 22 connected with a bellows head 24. A bellows 26 connects the body of the valve V with thehead 24 for sealing purposes in the usual manner. A hub 28 extends from the head 24 and an adjusting screw 3|] is threaded therein, the screw having a head 32 and being locked at adjusted positions by a nut 34. A return spring 35 .is

interposed between the body of the valve V and the bellowshead 24 for normally closing the valve V as in Figure l. I

Iprovide mechanism for actuating the valve V comprising a die plate 38 secured to the mountingplate ID by suitable posts and a series of levers and cams are mounted on the plate l0 and will now be described.

A valve and switch actuating lever 40 is pivoted at 42, has a protuberance 44 adapted to contact the head 32 of the screw and has an insulation extension 46 adapted to actuate a switch S. The spring tends to normally rotate the'lever clockwise.

An actuating lever 48 is pivoted at 50 and is normally biased upwardly by a spring 52 connected with one of the posts for supporting the side plate 38. This particular post is indicated at 54.

The lever 48 has pivoted thereto at 56 a pair of links 58 carrying a roller 60 between their upper ends. This roller is adapted to coact with a pair of notches 62 and 64 of the lever 40. The links 58 have a projection 90 to coact with the cam 16 as will hereinafter appear.

A shaft 66 is rotatably mounted and through suitable gearing 68 and 10 is driven at slow speed from an electric clock motor indicated generally at C. The shaft 66 carries a cam 12 of spiral character having a drop indicated at 14. A second cam is carried by the cam 12 and has a drop at l8. The cam 76 is adjustable relative to the cam 12 by being rotatable on the shaft 66 independent of the cam 12. An arcuate slot 80 and a clamp screw 82 are provided to retain the adjustment, whereas a set screw 84 threaded in an car 88 of the cam 12 and engaging an car 88 of the cam 16 serves as a means for micrometrically adjusting the cam 16 in relation to the cam 12.

The switch S comprises a base 92 on which is mounted a stationary contact 94, a movable contact 96, a contact actuating blade 98, a switch actuating blade I and a spring-extended toggle link 32 interposed between a pointed element I64 and the blade 98. This arrangement provides for snap action of the switch S.

The by-pass valve V is connected in a refrigeration system as shown diagrammatically in Figure l, the valve being in parallel with the usual expansion valve EV and condenser C of the system. The condenser of the system is shown at C, the evaporator at E, the refrigerant compressor at 08, and the refrigerant compressor motor at M. The system normally includes an automatic control such as a bellows I08 responsive to low side pressure in the system and operating contacts H0. The contacts 94 and 96 of the switch S are arranged to shunt the contacts H0 as shown.

Practical operation shaft 65 would rotate, for instance, once in 12 hours, although this period may be either shorter or longer if desired. The direction of rotation is counterclockwise.

In Figure 1 it will be noted that the drop 14 of the cam 12 is approaching the right hand end of the actuating lever 48. The valve V is closed. The defrosting period will commence when the drop 14 passes the end of the lever 48. After such passage has occurred as illustrated in Figure 2, the lever 48 is raised by the spring 52 and since the high portion of the cam 16 is against the projection. 90 of the links 58, the roller 60 will be thereby held in the notch 62 and rotate the valve and switch actuating lever 40 counterclockwise as illustrated. The relative strengths of the springs 52 and 36 are such that the spring 52 overcomes the spring 36 (the diilerence in leverage at 44 and 60 aiding in this respect), and the valve V is accordingly opened.

At the same time the switch S is permitted to close by reason of the projection 46 moving toward the right, and the actuating blade I00 of the switch returning to its initial shape as shown in Figure 2. This closes the switch with snap action, and the refrigerant compressor motor M is energized even though the bellows switch i08l i0 is not calling for refrigeration. Since the valve V is now open, the hot refrigerant from the compressor I06 Will by-pass the evaporator valve EV and the condenser C and flow through the evaporator E for melting the frost therefrom.

Referring to Figure 3, after a few more minutes of operation the projection 90 will fall off the drop 18 of the cam 16, thus permitting the roller Bllto be cammed by a projecting portion 63 of the lever 40 from the notch 62 to the notch 64 as illustrated, and as indicated by the arrow a. This permits the return spring 36 to expand and close the valve V.

The relatively strong spring 52 is now loaded throughout the remaining portion of the timing period by the counterclockwise rotation of the cam 12 which gradually lowers the lever 48 against the bias of the spring 52. This arrangement permits the relatively weak clock motor C to tension the spring 52 over a long period of time for eventual release again as in Figure 2.

The time for defrosting is represented by the projection dropping on 18 of the cam 16 in relation to the lever 48 dropping off I4 of the cam 12. The drops 90 and 48 may be relatively adjusted for longer or shorter defrosting periods by manipulation of the clamp screw 82 and the set screw 84 in an obvious manner.

A defroster control of the character disclosed permits a relatively rugged by-pass valve V to be operated with all the force necessary, but a relatively light motor, such as one of the electric clock type, is capable of resetting it for the next operation. The parts to accomplish this result are comparatively few and simple to manufacture and assemble.

Some changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim as my invention:

1. In a defroster control, a movable control element having a shallow notch and a deepnotch, an actuating element having a link pivoted thereto to engage said shallow notch, said notches being so shaped as to bias said link from said shallow notch to said deep notch, a spring to effectengagement of said link with said movable element and move said element to a position actuating said movable element, timer actuated cam means for gradually moving said actuating element back to a position with said spring loaded, and defroster terminating means comprising a second cam engaging said link to normally keep it in the shallow notch and permit it'to transfer to the deep notch when the second cam ceases'to engage the link.

2. In a defroster'control, a movablecontrol element having a shallow notch and a deep notch, said movable element having an operative position for effecting a defroster operation,'an actuating element having a link pivoted thereto to engage said notches, said link being normally engaged in said shallow notch, a spring acting through said actuating element to eifectsuch engagement, to bias said link toward saiddeep notchand to move said movable element to said operative position, cam means for gradually moving said actuating lever back to a position with said spring loaded, and defroster terminating means comprising a second cam carriedby the first cam and engaging said link to normally keep it in said shallow notch and to permit it to transfer to said deep notch at a predetermined position of said second cam.

3. In a defroster control, a timer actuated shaft, a spiral cam thereon having a drop, an

actuating lever engaging said cam, a spring to effect such engagement, a valve'actuating lever having a shallow notch and a deep notch, a link connected with said actuating lever, engaged in said shallow notch by said spring acting through saidv actuating lever and biased to transfer from said shallow notch to said deep notch by said spring, a second cam on said-shaft for retaining said link in said shallow notch against the-bias of said spring, said second cam having'a drop for permitting the link to drop into the deep notch, and defroster means adapted to be operated by said spring acting on said actuating lever when it drops on said first cam.

' 4. In a defroster control, a timer actuated shaft, a spiral cam thereon having a, drop, an actuating lever engaging said cam, a spring to effect such engagement, a control lever having a shallow notch and a deep notch, a link connected with said actuating lever and biased by'said spring acting through said actuating lever to transfer from said shallow notch tosaid deep notch, a second cam on saidshaft for retaining said link in said shallow notch, said second cam having a drop for permitting the link to drop into said deep notch, and a spring-loaded defrosting means adapted to be operated against itsspring load by said spring acting on said actuating lever when it drops on said first cam. ,7 k 5. In a defroster control, a timer actuated shaft, aspiral cam thereon having a drop,-an actuating lever engaging said cam, a spring to effectsuch engagement, a defroster lever having a shallow notch and-a deep notch, a link connected with said actuating lever and biased by said spring actingthrough said actuating lever to engage said notches, said link being normally engaged with said shallow notch but constrained toward said deep notch by said spring, a second cam on said shaft for retaining said link in said shallow notch against the action of said spring, said second cam having a drop for permitting the link to drop into said deep notch, and defroster means adapted to be operated by said spring acting on said actuating lever when it drops on said first cam.

6. In a control of the character disclosed, a defroster control lever biased to moveto a normal position, a spring-loaded secondlever, a link for operatively connecting said second lever to said defroster control lever to move said defroster control lever under the bias of said spring-loaded lever, a motor driven cam for gradually moving said spring-loaded lever and thereby loading its spring, said cam having a drop for releasing said spring-loaded lever, said spring-loaded second lever thereupon acting through said link to move said defroster control lever, one of said levers having a shoulder against which said link is normally engaged by said spring-loaded lever, and a second cam operable to release said link so that said spring-loaded lever can disengage said link from said shoulder whereby said defroster control lever can be moved by its bias to said normal position for terminating the defrosting period.

7. In an automatic defrost control device for use in a refrigeration system, a valve, a first spring for biasing said valve in a closed position, a second stronger spring capable when stressed and operative when released from a stressed position to open said valve with a snap action against said first spring, a synchronous timer motor, means driven by said motor for stressing said second spring over a period of time and for effecting its release at a predetermined time, a member movable to a first position in which said second spring is rendered operative when released from its stressed position to open said valve and to hold it open, and movable to a second position in which said second spring is rendered inoperative to hold said valve open, whereby said valve may again be closed with a snap action by said first spring, spring means for biasing said member in one position, and means driven by said motor for moving said member to its other position.

8. In an automatic defrost control device for vuse in a refrigeration system, a valve, a first spring for biasing said valve in a closed position, a second stronger spring, a synchronous timer motor, means including speed reduction gearing and cam means driven by said motor for building up a, stress in said second spring over a period oftime and for subsequently effecting its release at a predetermined time, a member movable to a first position in which said second spring is rendered operative to open said valve with a snap action and to hold it open whenreleased from its stressed position, and movable to a second position in which said second spring .is inoperative to affect said valve, whereby it may be again closed with a snap action by said first spring, resilient means for biasing said member to one position, and means driven by said motor for moving it to its other position. 9. Inan automatic defrost control device for use in a refrigeration system, a valve. a switching device, a first spring for biasing said valve in a closed position, a second stronger spring, a synchronous timer motor, means driven by said motor for buildingup a stress in said second spring over a period of time and for effectingits release at a predetermined time, a member movable to a first position for rendering said second spring operative when released from its stressed position to open saidvalve with a snap action and to hold it open, and movable to a second position in which said second spring is inoperative-to hold said valve open whereby it may again be closed with asnap action by said first spring, spring'rneans for biasing said member in one position, means driven by said motor for movingsaid member to its other position, and a member movable with said valve for the actuation of said switching device. I

10. In a device of the class described, a control member movable oppositely between two control positions, an actuator therefor, afirst spring for moving said control member to a first position, a second stronger spring, an operative connection between said second spring and said actuator, said second spring being arranged to act opposite in relation to said first spring and capable when released after being stressed of moving said control member through said actuator and said operative connection to its second position and holding it there, said second spring having a normal unstressed position in which said first spring is permitted to move said control member to its first position, a timer motor, cam means driven by said motor for stressing said second spring over a period of time and for restraining it while it is being stressed, a second cam means for restrainingone element of said operative connection while said second spring is being stressed, said first cam means releasing said second spring at a predetermined time and after said spring has been stressed, whereby to move said control member through said actuator under the action of said second spring, and said second cam means subsequently releasing said element to permit said first spring to move said control member.

11. In a device of the class described, a valve, a first spring for biasing said valve in a closed position, a second stronger spring, an operative connection between said second spring and said valve, said second spring through said operative connection being capable when released after being stressed of opening said valve against said first spring, a timer motor, means driven by said motor for stressing said second spring over a period of time, said means also restraining said second springwhile it is being stressed, means driven by said motor for releasing the energy stored in said second spring at a predetermined time and after said spring has been stressed, one element of said operative connection being movable to a first position by said second spring and operative through another element of said operative connection when the spring is released to open said valve and to hold it open, and movable to a second position in which said second spring is rendered inoperative to hold said valve open, and means driven by said timer motor for moving'said one element to a third position at a predetermined time whereby it is subsequently operative to utilize the release of said second spring to open said valve.

12. In a device of the class described, a valve, a first sprin for biasing said valve in a closed position, a second stronger spring, an actuating lever to which said second spring is connected, said second spring through said actuating lever being operatively capable of opening said valve and holding it open against said first spring when said second spring is released after being stressed in a direction opposed to said first spring, a timer motor, a shaft driven by said motor, speed reduction gearing between said motor and said shaft, a first cam on said shaft for engaging said actuating lever to move one end of said second spring ina direction and to a position over a period of time wherein it is stressed to oppose said first spring, said cam restraining said-actuating lever andthereby said second spring While it is being stressed and subsequently releasing said actuating lover, a member for transferring movement of saidactuating lever to said valve, a second cam rotatable with said shaft for restraining said member until after said first cam has released said actuating lever at a preselected time and after said second spring has been stressed, said second cam being rotatable with said shaft and angularly adjustable thereon for releasing said member a preselected interval after the release of said actuating lever whereby said member is subsequently operative to utilize the release of said'second spring to open said valve.

13. In a defroster control of the character disclosed, a defroster control lever biased to position for discontinuing a defrost operation, a spring loaded second lever,a link to move said defroster control lever, said link being pivoted to one of said levers, the other of said levers having a double notch with one of the notches deeper than the other, said link normally engaging in the shallower notch and biased by said spring loaded lever toward the deeper notch, a clock motor driven cam for gradually moving said spring loaded lever and thereby loading its spring, said cam having a drop for releasing said spring loaded lever whereupon it is moved by its spring and said link is thereupon moved by said springloadedilever for moving said defroster control lever against its bias, and a second clock driven motor cam operable to disengage said link whereupon said spring loaded lever moves said link'from the shallow notch into the deeper notch for permitting the bias for said defroster control lever to act and thereby terminate the defrosting period.

HAROLD S. KING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,351,140 McCloy June 13, 1944 2,433,574 Newton Dec. 30, 1947 2,451,682 Lund Oct. 19, 1948 2,463,027 Frie Mar. 1, 1949

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