US2324309A - Refrigeration apparatus - Google Patents

Description

July 13, 1943 G. s. M cLoY REFRIGERATION APPARATUS Filed Aug. 6, 1942 INVENTOR GRRHRM 5. MCCLQY.

Fla. 1.

WITNESSES:

BY E g ATTORN Y Patented July 13, 1943 REFRIGERATION APPARATUS Graham S. McCloy, Springfield, Mass, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 6, 1942, Serial No. 453,763

5 Claims.

My invention relates to refrigeration apparatus and particularly to automatic defrosting of the cooling element of such apparatus.

It is desirable to defrost the cooling element of a refrigerator very frequently, for example every day, to obtain maximum heat transfer between the cooling element and the media to be refrigerated. It has, therefore, been the practice in some cases to provide a defrosting clock which renders the refrigerating system inactive every twenty-four hours for a suflicient time to effect defrosting.

However, the major portion of the moisture which is condensed and forms frost on the cooling element is obtained from the air in the refrigerator. Each time the refrigerator door is opened, a charge of moisture laden air enters the refrigerator, it being obvious, therefore, that the amount of frost on the cooling element is in nearly direct ratio for given average cooling element temperatures to the number of door openings. A clock defrosting device has no relation to the amount of frost on the cooling element, with the result that if the refrigerator door is not opened for twenty-four hours, the refrigerator cooling element is defrosted when it is unnecessary, thereby raising the'temperature of the refrigerator and its contents and requiring additional unnecessary power consumption after defrosting to reduce the temperatures to normal. On the other hand, if the refrigerator is being used constantly and the door is being opened many times in a day, defrosting may be necessary in less than twenty-four hours. Defrosting devices directly responsive to the thickness of frost on the cooling element are either quite complicated or lack dependability.

It is, therefore, an object of my invention to provide intermittent defrosting of the cooling element of a refrigerator in response to an operation or use of the refrigerator which has substantially a direct relationship with the quantity It is a further object of my invention to pro-1 vide a defrosting device responsive to refrigerator door openings for initiating a defrosting period and responsive to the cooling element temperature for ending a defrosting period and restoring normal operation of the refrigerating system.

,These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. l is a sectional view of a refrigerator cabinet and mechanism embodying my invention; and,

Fig. 2 is a schematic view of a mechanism to initiate and terminate a defrosting period in ,accordance with my invention.

Referring specifically to the drawing for a detailed description of my invention, numeral H designates generally a refrigerator cabinet having a food-storage compartment 12 and a machinery compartment l3. The food-storage compartment is provided with an access opening 84 closed by a hinged door l5. An evaporator or cooling element 16 refrigerates the air in the food-storage compartment [2 to preserve food stored therein.

A hermetically sealed motor compressor unit H, a condenser l8 and a motor driven fan IQ for cooling the condenser are disposed in the machinery compartment I3. The refrigerating system is of the compression type having a motor 2| driving a compressor 22. Compressed refrigerant vapor is delivered to the condenser l8 wherein it is condensed by the cool air from the fan l9. Condensed refrigerant is delivered through a capillary tube flow restricting device 23 to the evaporator l6 wherein the condensed refrigerant vaporize s and absorbs heat. Refrigerant vapor is withdrawn from the evaporator l6 through a conduit 24 by the compressor 22, whereupon the refrigeration cycle is repeated.

A standard adjustable temperature control, shown diagrammatically at 25, is provided for normally controlling cyclic operation of the motor 2| and compressor 22 to maintain an average evaporator temperature below the freezing point of water, at which temperature moisture is condensed from the air in the food-storage compartment l2 and is deposited on the evaporator [6 in the form of frost.

As stated hereinbefore, intermittent automatic defrosting of the evaporator 16 is effected in response to the number of times the door I5 is opened. A mechanism for initiating a defrosting period in response to door openings and terminating said defrosting period in response to ing moved from one tooth to another.

evaporator temperature is indicated generally at 33. The mechanism 28 comprises an operating plunger 21 which is forced inwardly each time the door I is closed. A tension spring 23 is attached to the plunger 21 and to a portion 33 of the refrigerator cabinet Ii to pull the plunger 21 outwardly when the door I3 is opened. The plunger 21 is attached to a freely rocking lever 3| having a pawl 32 attached thereto. A ratchet wheel 33 having teeth 34 is rotated by movement of the plunger 21, lever 3i and pawl 33, the pawl 33 engaging the teeth 34 of the ratchet wheel 33. A retaining pawl 35 also engages the teeth 34 and allows rotation of the ratchet wheel 33 in a clockwise directbn, but prevents it in a counter-clockwise direction while the pawl 32 is be- The ratchet wheel 33 is provided with a fixed arm 33 which engages a snap-acting device 31 to open a set of contacts 33. A stop 39 limits the movement of the snap-acting device 31. The contacts 38, when closed, establish a flow of current to the temperature control devic 25 and motor 2| through a source of power L1, L2 and when open, interrupt said flow of current. After the arm 36 has operated the snap-acting device 31 to open the contacts 38, the evaporator l6 rises in temperature due to heat leakage into the refrigerator cabinet I l, and the evaporator is defrosted after a short period of time.

When the evaporator temperature reaches a predetermined temperature above the freezing point of water to insure that all the frost has melted oif, expansible fluid contained in a bulb 4| expands, causing expansion of a bellows 42 which is connected to the bulb 4| by a conduit 43. As the bellows 42 expands, it moves a lever 44 which engages a member 45 which carries the movable portion of the contact 38. Lever 44 also engages one end of the snap-acting device 31, causing it to snap into the position shown in Fig. 2 and close the contacts 38. It-is apparent that the defrosting period is terminated in response to evaporator temperature and the refrigerating mechanism again cycles to maintain an average evaporator temperature below freezing, as determined by the setting of the temperature control 25.

The ratchet wheel 33 shown in Fig. 2 by way on refrigerators shipped to such a locality.

From the foregoing it will be apparent that I have provided a new defrosting device which in-.

. termittently automatically effects defrosting of the cooling element of a refrigerator in response to the number of times the access door is opened.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes andmodifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

1. In refrigeration apparatus, the combination of a refrigerator cabinet having a food-storage compartment provided with an access opening therein, a door movable for opening and closing the access opening, a cooling element for refrigerating the air in said food-storage compartment, refrigerating apparatus for normally maintaining said cooling element at an average temperature below the freezing point of water, at which temperature it collects frost from the moisture in said air and means responsive to the opening and closing of said door a predetermined plurality of times to modify the operation of said refrigerating apparatus to permit the temperature of said cooling element to rise above the freezing point of water.

2. In refrigeration apparatus, the combination of a refrigerator cabinet having a food-storage compartment provided with an access opening therein, a movable door for opening and closing the access opening, a cooling element for refrigerating the air in said food-storage compartment, refrigerating apparatus for normally maintaining said cooling element at an average temperature below the freezing point of water, at which temperature it collects frost from the moisture in said air and means for modifying the operation of said refrigerating apparatus to permit the temperature of said cooling element to rise above the freezing point of water, in response to the opening and closing of said door a predetermined plurality of times, and for reestablishing normal operation of said refrigerating apparatus in response to an above freezing temperature of said cooling element.

3. In refrigeration apparatus, the combination of a refrigerator cabinet having a food-storage compartment provided with an access opening therein, a door movable for opening and closing the access opening, a cooling element for refrigerating the air in said food-storage compartment, refrigerating means for normally maintaining the temperature of said cooling element below the freezing point of water, at which temperature it collects frost from the moisture in said air, and means operative by the opening and closing of said door a predetermined plurality of times to modify the operation of said refrigerating means and thus permit a rise in the temperature of said element above the freezing point of Water.

4. In refrigeration apparatus, the combination of a refrigerator cabinet having a food-storage compartment provided. with an access opening therein, a door movable for opening and closing the access opening, a cooling element for refrigerating the air in the food-storage compartment, means for circulating a refrigerant through said cooling element; control means for normally operating said refrigerant circulating means to maintain an average temperature of said cooling element' below the freezing point of water, at which temperature the cooling element collects frost from the moisture in said air and means for intermittently modifying the operation of said refrigerant circulating means when said door has been opened and closed a predetermined plurality of times to raise the temperature of said cooling element and effect defrosting of said cooling element.

5. In refrigeration apparatus, the combination of a refrigerator cabinet having a food-storage compartment provided with an access opening therein, a door movable for opening and closing the access opening, a cooling element for refrigerating the air in the food-storage compartment, means for circulating a refrigerant through said cooling element, control means for normally operating said refrigerant circulating means to maintain an average temperature of said cooling element below the freezing point of water, at which temperature the cooling element collects frost from the moisture in said air, means for intermittently superseding said control means and for modifying the operation of said refrigerant circulating means when said door is opened and closed a predetermined plurality of times to raise the temperature of said cooling element and permit defrosting of said cooling element and means responsive to an above freezing temperature of said cooling element for restoring control of said circulating means to said control means.

GRAHAM S. McCLOY.

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