US 2717494 A
Description (OCR text may contain errors)
Sept. 13, 1955 R. w. DOEG REFRIGERATING APPARATUS Filed Jan. 13, 1954 JNVENTOR. RALPH M D056' BY WGTM Arron/vir United States Patent O r``ce 2,717,494
REFRIGERATING APPARATUS Ralph W. Docg, Detroit, Mich., assigner to Nash-Kelvinator Corporation, Detroit, Mich., a corporation of Maryland Application January 13, 1954, Serial No. 403,842
3 Claims. (Cl. 62-3) This invention relates generally to the refrigerating apparatus and particularly to controls for controlling defrosting of a refrigerating apparatus evaporator.
It is an object of the invention to provide for refrigerating apparatus an improved control which is manually operable to initiate a defrosting cycle of the apparatus and which is automatically actuated in response to increase in the temperature above normal operating temperature to terminate the defrost cycle and return the apparatus to the normal refrigerating cycle.
Another object of the invention is to provide for a defrost cycle control having a valve and actuators therefor an improved mechanism for operatively connecting the valve and actuators to effect inexpensive, yet efficient and sensitive, control.
More specifically, it is an object of the invention to provide an improved arrangement of the components of a defrost cycle control including a valve operated through a toggle either by a manual push button to initiate the defrosting cycle or by a thermostat responsive to predetermined increase in evaporator temperature to terminate the defrosting cycle.
Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.
In the drawings:
Fig. l is a diagrammatic illustration of a refrigerating apparatus including my defrost cycle control; and
Fig. 2 is a cross sectional view of my defrost cycle control.
Referring to the drawing by characters of reference, my defrost cycle control valve, designated generally by the numeral 20, is illustrated with a refrigerating apparatus of the well known type having the usual refrigerant motor-compressor unit 22, a condenser 24, and an evaporator 26. These units are connected together communicatively in the well known manner by conduits including a small diameter conduit or capillary tube 28 which connects the outlet of condenser 24 to the inlet of evaporator 26, and a refrigerant return conduit 30 which connects the outlet of the evaporator to the inlet of the motor-compressor unit 22. A conduit 32, connects the outlet of the motor-compressor unit 22 to the inlet of the condenser 24. It is to be understood that in practice, a thermostat (not shown) of any suitable type is used to control cycling operation of the motor-compressor unit 22 in response to the temperature of the evaporator whereby to maintain a substantially constant evaporator temperature. During the normal refrigeration cycle, liquid refrigerant is conducted by the capillary 28 from the condenser 24 to the evaporator 26, and vaporous refrigerant is conducted by the return conduit 30 to the motorcompressor unit 22 from which compressed vaporous refrigerant is delivered by conduit 32 to the condenser 24. It will also be understood that the above described refrigerating system may be provided with a cabinet of any suitable type such as the domestic refrigerator cabi- Patented Sept. 13, 1955 net shown in my Patent No. 2,638,753, issued May 19, 1953, and entitled Refrigerating Unit Mounting.
A by-pass conduit 34 connects the conduit 32 to the inlet of the evaporator 26, thus by-passing the condenser 24, and ow through the by-pass 34 is controlled by the valve 20. The valve 20 is normally closed to effect normal refrigeration cycling of the apparatus, but when valve 28 is opened, the hot compressed vaporous refrigerant discharged by compressor 22 passes through the by-pass conduit 34 because this conduit is of larger diameter than the condenser inlet, thus offering the path of least resistance to flow of the refrigerant. The hot vaporous refrigerant circulates through the evaporator 26 heating the same to defrost the evaporator quickly after which the valve 20 operates automatically to return the apparatus to normal refrigerating operation.
The valve 20 includes a support or casing 36 having a bottom wall 38, opposite upright walls 4t) and 42, and a separate top wall or cap 44. In order to give access to the interior of the casing, the front thereof may be closed by a removable plate (not shown) which may be detachably secured to the casing proper.
Within the casing 36 and mounted on the bottom wall 38 thereof is a valve body 46 having a passage therethrough provided with an inlet 48 and an outlet 50 which are connected in and to the by-pass conduit 34. A valve seat member 52, secured to and within the valve body 46, provides a port 54 and seat for a movable valve member 56. The valve member 56 has a valve stem 58 which extends upwardly through a clearance bore 60 in the valve body 46 and projects from the top thereof to be secured to a movable wall 62 of a bellows or diaphragm seal 64. The opposite end of the bellows 64 is sealed and secured to the top of the valve body 46 around the entire periphery thereof to seal the body against leakage of refrigerant by way of the valve stem clearance bore 60. Valve 56 is biased to closed position by the movable wall 62 of the seal, as said wall is tensioned to move or flex upwardly to move the valve to its seat. Valve closing action is aided by refrigerant pressure acting against the valve head.
The valve member 56 is actuated through operation of a toggle comprising an upper arm 66 and a lower arm 68 which have inner ends connected together by a pivot pin 70. The upper end of the upper toggle arm 66 is pivoted to a depending ange 72 of the casing top wall 44, and the lower end of the lower toggle arm 68 is connected by a link '74 to the casing sidewall 40. The link 74 extends substantially horizontally and controls movement of the lower end of toggle arm 68 so that the arm is guided to impart vertical movement in flexing wall 62. The upper end of the valve stem 58 is sealed and secured to the bellows 64 and has a head 76 externally thereof which provides a bearing surface for the lower end of the toggle arm 68.
Mounted on the casing wall 4t) is a manual actuator or push rod 78 to actuate the toggle in a direction to open the valve member 56. The push rod 78 is slideably supported in a sleeve 80 which is secured in and to the casing wall 40. A push button head 82 on the outer end of the push rod 78 is abutted by one end of a coil spring 84 which surrounds the sleeve 80 and acts to move the rod outwardly away from the toggle when the button is released by the operator. The inner end of the push rod 78 is preferably rounded, as at 86, and preferably engages the toggle arms 66 and 68 adjacent the toggle pivot 70 thereof. The toggle arms 66 and 68 are shown in full lines as having been moved by push rod 78 to the over-center position or position in which the toggle holds the valve member 56 in open position. When the toggle arms are so positioned, the valve member 56 will be held open against the tensioned wall 62 and the refrigerant pressure acting at the inlet 48 to close the valve.
On the casing wall 42 is a thermostatically actuated push rod 90 in axial alignment with manual push rod 78 and adapted to actuate the toggle in a direction to permit closing of the valve member 56 by the tensioned wall 62 and refrigerant pressure acting thereagainst. The thermostatic actuator comprises in general a bellows 92, a body 94, a tube 96, and a feeler bulb 98. These are communicatively connected and are completely filled with a temperature responsive, expansible-contractible fluid to actuate the bellows 92, and the feeler bulb 98 is attached to the evaporator 24 so that the bellows 92 responds to changes in evaporator temperature. The bellows 92 has a fixed wall 100 which is sealed and secured to the body 94, and has a movable wall 102 which is sealed and secured to the push rod 90.
The thermostatically operated push rod 9) is supported and guided by a lever 104 which is pivoted intermediate the ends thereof by a pin 106 to the rod 90 and to the cap flange 72 by a pin 107. To the lower end of the lever 104 is connected one end of a spring 108 which has its other end attached to the casing wall 42 by an adjustment screw 110. Spring 108 yieldingly opposes the thermostatic actuator 92 and so by adjusting the spring tension the evaporator temperature at which the valve 56 will close may be determined. The spring 108 is adjusted such that thermostatic actuator will not actuate the toggle during the normal refrigerating cycle of the apparatus. That is, the thermostatic actuator is set to close valve 56 only at evaporator temperatures above normal operating temperature of the evaporator. A
When defrosting of the evaporator is desired, the push button 82 is pressed inwardly resulting in rod 78 pushing the toggle to the over-center position against the opposing refrigerant pressure and the biasing action of wall 62. In this position of the valve 56, hot vaporous refrigerant from the compressor 22 by-passes the condenser 24 and flows through the by-pass conduit 34 into the evaporator where the hot vaporous refrigerant quickly raises the evaporator temperature to melt the frost therefrom. As the temperature of the evaporator 26 increases, the bellows 92 expands and pushes rod 90 to move the toggle over-center in the opposite direction. The thermostatic actuator is only required to break the toggle after which the refrigerant pressure at the inlet acting on the valve head and the tensioned wall 62 moves the valve 56 to closed position against seat 54. This closes the by-pass conduit 34 to refrigerant flow and automatically returns the apparatus to the normal refrigerating cycle.
From the foregoing description, it will be understood that I have provided for refrigerating apparatus an improved defrost cycle control which functions manually to set and hold the valve open to initiate the defrost cycle and which functions automatically to release the valve to return the apparatus to the normal refrigerating cycling. It will be further understood that by arrangement of the toggle so that it can be set manually to hold the valve open results in an inexpensive, yet efficient, device which is sensitive on closing the valve since only slight movement of the toggle overcenter is required by the thermostatic actuator to allow the valve to snap shut. In addition I have provided a defrost control device having an improved mechanism for operatively connecting the manual and thermostatic operators to a valve for controlling the defrosting cycle.
1. A control device for use in controlling the defrost cycle of a refrigerating apparatus comprising, a support, a valve body mounted on said support having a refrigerant ow passage therethrough, a movable valve member controlling said passage having a valve stem projecting from said valve body, said valve member being movable in one direction to open said passage to refrigerant flow therethrough and movable in the opposite direction to close said passage to liow therethrough, means acting to move said valve member in said opposite direction, a bellows surrounding said valve stem and sealed to said valve body, said bellows having a movable wall, means connecting said valve stem to said movable wall and forming a bearing surface on the latter externally of said bellows, a pair of toggle links having inner movable ends pivoted together and the outer end of one of said links pivoted to said support, the outer end of the other of said links engaging the said bellows bearing surface, a link pivoted at one end to said support and at the other end to the outer end of the said other of said toggle links, a manually operable push rod engageable at one end thereof with the inner connected together ends of said toggle links and operable to actuate said toggle to move said valve member in said one direction to open the passage to refrigerant flow, a second and thermostatic push rod in axial alignment with the first push rod on the other side of said toggle from said rst push rod, said second push rod engaging the connected together ends of said toggle and operable through said toggle to allow said valve member to be moved to closed position, a lever pivoted to said support and to said second push rod, and a spring acting on and opposing said second push rod.
2. A defrost cycle control device comprising, a casing, a valve body within and mounted on said casing, said valve body having an inlet and an outlet, a pressure responsive valve member anterior to and controlling said inlet, a valve stem on said valve member projecting from said valve body into said casing, a diaphragm sealed and secured to said valve body around said stem and having a movable wall sealed and secured to said stem, said diaphragm movable wall biasing said valve member to closed position, a bearing member carried by said movable wall, a pair of toggle arms having inner ends pivoted together and having the outer end of one arm pivoted to said casing and the outer end of the other arm engaging said bearing member, a link connecting the outer end of said other arm to said casing to control movement of said arm, said toggle arms being movable to open said valve member and to a position in which the pivot of the inner ends of said arms are slightly overcenter to hold the valve member open against the biasing action of said diaphragm movable wall, a push rod manually operable to move said toggle arms to the position holding said valve member open, and a thermostatically operated push rod operable to move said arms to release said Valve member for closing by said diaphragm movable wall.
3. In a refrigerant flow control device having a valve member movable in one direction by a manual actuator and in the opposite direction by a thermostat, mechanism for operatively connecting the valve member to both the manual actuator and the thermostat comprising, a lever for actuation respectively by the manual actuator and thermostat, a second lever to actuate the valve, and a link connecting the free ends of said levers together forming therewith an abutment for engaging by either the manual actuator or thermostat and a second abutment for engaging the valve.
References Cited in the le of this patent UNITED STATES PATENTS 1,982,582 Lovekin Nov. 27, 1934 2,049,625 Ruppricht Aug. 4, 1936 2,638,753 Doeg May 19, 1953