US2266373A - Unit cooler - Google Patents

Description

Dec. 16, 1941. c. D. MARLO 2,266,373

UNIT COOLER Filed Feb. 17, 1939 2 Sheets-Sheet l C. D. MARLO Dec. 16, 1941.

UNIT COOLER Filed Feb. 17, 1959 2 Sheets-Sheet 2 Patented Dec. 16, 1941 ourr COOLER Caesar D. Marlo, St. Louis, Mo., asslgnor to Marlo Coil Company, St. Louis, Mo., a partnership composed of A. T. Marlo, C. D. Mario, and L. C.

Pellegrinl Application February 17, 1939, Serial No. 256,880

4 Claims.

This invention relates to unit coolers, and has special reference to coolers assembled as unitary portable coolers adapted to be located in cooling or refrigerating rooms or compartments for reducing the temperature therein to as low a degree as desired.

Objects of the invention are to provide an improved cooler constructed and assembled as a unitary device adapted to be placed in a room or compartment in which the temperature is to be reduced to a low degree, and having means for creating a circulation of cooled or refrigerated air within the room or compartment; to provide such a device including a portable housing having insulating walls for the refrigerating or cooling and air circulating devices; to provide shutters mounted and arranged to be opened and held opened by the movement of the air through the cooler when the air circulating device or blower is in operation; to provide an improved arrangement of the coils within the housing so as to eliminate short-circuiting of the refrigerant and to insure maximum capacity of the cooler; to provide an improved defrosting device arranged in a novel relationship to the coils so as to effect speedy defrosting of the coils without substantially modifying the temperature within the room or compartment in which the unit is located; and to provide improved means for suspending or supporting the cooler.

Another object of the invention is to provide a cooler for effecting forced circulation of air between series of refrigerating coils, a housing for enclosing the cooler mechanism as a unit, means for defrosting the coils speedily and effectively, and shutter devices for closing the housing during the defrosting operation so as to prevent the warm air resulting from the defrosting operation from passing from the unit into the room or compartment in which it is mounted.

Other objects of the invention will be readily apparent from the following description, reference being made to the annexed drawings, in

whichv Fig. 1 is a top plan view of my improved unit cooler with part of the top wall broken away.

Fig. 2 is an elevation with parts broken away showing that side of the housing through which the air enters.

Fig. 3 is a horizontal sectional view approximately on the line 33 of Fig. 2.

Fig. 4 is a view showing a portion of one side of the cooler, one of the detachable panels opposite the ends of the refrigerating coils being removed.

Fig. 5 is an elevation showing one end of the cooler.

Fig. 6 is an elevation showing the opposite end of the cooler.

Fig. 7 is an enlarged sectional view approximately on the line 1-1 of Fig. 2.

The housing may be made of any size adapted for its intended use and comprises side, end, top, and bottom walls including on the inside sheets i of insulating material which are covered on the outside by metallic sheets 2. One of the vertical walls of the housing is formed with an opening in which a metallic frame 3 is mounted and retained by fasteners 4. Within the open frame 3, which provides an opening for the flow of air into the housing, an automatically operated shutter, comprising a vertical series of shutter strips 5, is mounted. These shutter strips may be made of aluminum, aluminum alloy, or other light and preferably noncorrodible material, having their upper edges mounted on pivots 6 with the lower edges of the respective strips 5 extending downwardly from the upper margins of the adjacent lower strips (Fig. 7). This provides for inward swinging and opening of the shutter when subjected to the pressure of air circulated through the refrigerating unit by the forced circulating device,

That wall of the housing directly opposite from the wall containing the frame 3 has a complementary opening in which a frame 1 is mounted. A shutter device is mounted in the frame 1 and comprises a vertical series of strips 8 which may be made of the same material forming the strips 5 so as to swing freely on their supporting pivots 8. The upper edges of the strips 8 are mounted on the pivots 9 and the lower margins of the respective strips 8 extend downwardly beyond the upper margins of the adjacent lower strips so that, when the strips are in closed position as shown in solid lines (Fig. 7), a complete closure for the outlet of the housing is provided. The lower margins of the respective strips 8 extend on the outside of the adjacent lower strips so that all of the strips may be swung outwardly to open position by the forced current of circulating air.

The refrigerating coil core comprises a series of spaced fins l0, and a series of tubes H extending therethrough and having their ends connected by return bends I2 and providing a unit adapted to be mounted in the assembly conveniently and without interference with other parts. I 3 is the inlet of the coils and may be detachably connected with one end of one of the bottom tubes II. A pressure relief valve l4 of known construction is connected as a by-pass around the outlet valve I 1. Thus should the pressure in the coil become excessive, the pressure relief valve l4 functions to permit the refrigerant to-pass around the valve l1 if it is closed. This is especially desirable since heat may be applied to the coil by the defrosting device and will raise the temperature and pressure of the refrigerant above that usually encountered. The refrigerating coil may be removed as a unit through the end of the compartment, provided with a removable panel 18 closing the opening IS in the housing. This panel fits in the opening l9 and is attached to the wall of the housing by nuts 20 screwed on the ends of bolts 2 I.

Two retaining members 22 and 23 are rigidly attached to the inside of a pan or tray 24 within the housing, and serve to position the coil. The pan or tray 24 is attached to the bottom wall of the housing by fasteners 25. The lower ends of the fins 10 are formed with notches 26 (Fig. 7), permitting water obtained from defrosting of the tubes 1 l to flow to the drain pipe 21 opening through the bottom of the pan 24. The ends of the retaining members 22 and 23 are separated from the end walls of the pan 24 by spaces 28 (Fig. 3), also provided to permit water to flow freely to the drain 21.

The coil unit is attached to a pair of rigid frame members 29 by bolts 30 engaging parts of the coil unit and having threaded ends extending through the members 29 and provided with nuts 31 whereby the bolts 30 may be tightened. The members 29 may be formed with holes 32, permitting free movement of air therethrough at the ends of the coil unit and preventing formation of air retaining pockets.

The defrosting device comprises a series of tubes 33 extending through the fins l below the coil tubes H. These tubes 33 are preferably of copper and, as shown, are of larger diameter than the tubes ll, although the relative dimensions of these tubes may be varied optionally. Electrical heating elements 34 extend through the tubes 33 and may be connected as shown in series. Electricity is supplied to the heating elements by circuit wires 35 and 31. When the circuit through the wires 31 is closed, the heating elements 34 are heated and, as a consequence, the tubes 33, fins l0, and tubes I l are heated sufficiently to melt the frost on the tubes and to heat the air within the housing. As a consequence, the water produced by the melting of the frost on the tubes drops, or flows along the has It, into the pan or tray 24 and is-discharged through the drain 21. During this defrosting operation, which usually requires only from ten to fifteen minutes, the shutters and 8 are closed, thereby preventing the warm air from passing from within the housing into the room or compartment in which the refrigerating unit is located. The manner in which the shutter strips 5 and 8 are pivotally supported at theirupper edges and leaving the lower portions thereof extending downwardly, constitutes means for automatically closing the shutters by gravity when the fan and motor are idle.

The heating tubes are located so that they will heat the coils by conduction, radiation and convection as well as by circulation of the refrigerant within the coils. The position in which aaeasvs they are placed causes the refrigerant in the coils near the heaters to become warm. This. of course, causes a rise in the pressure of the refrigerant in this portion of the coil. The pressure rise causes a movement of the refrigerant away from the heat coils which eflects a circulation of the refrigerant within the coils to aid in the defrosting process. By utilizing tubes placed in the fins as shown, for encasing the heating elements, the same machinery used to space and align the refrigerant tubes may be used for fabricating the heating tubes and a veryeconomical construction is achieved. Placing the heating elements beneath the refrigerant tubes and in line therewith increases the emcacy of the device. The insulated housing keeps the heat in and the cold out during a defrosting operation and thus shortens the time required for defrosting as well as prevents raising of the refrigerator temperature. A switch (not shown) is provided in connection with the wires and 31 to open and to close the circuit, and it will be understood that said switch is kept open when through an opening 42 in the housing wall and into a box 43 having a removable sliding wall 44. The opposite ends of the heating elements 34 extend through an opening 45 in the panel l8 and into a box 46 having a removable sliding wall 41 which may be removed to afford access to the ends of the heating elements 34 and their connections 36, and then replaced as desired.

A frame 48 is attached to the frame 1 and supports a motor 49 within the housing. A fan 50 is attached to and operated by the shaft 5| of the motor 49 within a circular opening in a frame 52 attached to the frame 1 and adjacent to the strips 8. Electric circuit wires 53 furnish power for the fan.

When the compressor is operating and the valve I1 is open, refrigerant is forced through the tubes II, and low temperatures can be obtained, ranging from about 32 F. to about 20 below zero, thus adapting the device for such low temperature work, as in ice-cream hardening rooms, etc. The device may be suspended by hooks or eyelets 56 attached to the housing and adapted to engage hangers 51 within the room or compartment containing the device.

When the motor. 49 and fan 50 are operating, a flow of air'through the housing is caused by suction of the fan 50. The air passes between and across the tubes ll of the refrigerating coil and is expelled from the housing through spaces provided by the opening of the shutter strips 8. This suction also opens the shutter strips 5. During this operation, the circuit through the wires 35 and 31 is open.

When it is desired to defrost the coils, the circuit through the wires 53 is opened and the motor 43 and fan 50 are stopped, as a consequence of which the suction of air into the housing is also stopped. When the suction of air is stopped, the shutter strips 5 and 8 move to closed position, and the circuit through the wires 35 and 31 is then closed to heat the heating elements 34 by. which the heating unit is defrosted. The defrosting requires only a com-' paratively short time, usually from ten to fifteen minutes. After the heating unit has been defrosted-the circuit through the wires 35 and 31 may be manually opened and the motor 49 and fan 50 again placed in operation by closing the circuit through the wires 53.

It should now be apparent that this invention attains all ofits intended objects and purposes in a highly efficient, economical and satisfactory manner. The construction, arrangement and relationship of the parts may be varied as widely as the scope of equivalent limits will permit without departure from the nature and principle of the invention.

I claim: Y

1. A refrigerating coil comprising a plurality of spaced, parallel, vertical fins, a plurality of spaced, parallel tubes for carrying refrigerant passing through the fins horizontally and arranged in vertical rows, a plurality of tubes beneath said rows passing through the fins and provided with electrical heating elements, a shutoff valve in the outlet of said refrigerating coil and a by-pass valve around the shut-off valve arranged to operate at a predetermined temperature or pressure to relieve the pressure in the coil ii the shut-off valve is closed.

2. A refrigerating coil comprising a plurality of spaced, parallel, vertical fins, a plurality of horizontal tubes that are secured to the fins and arranged to carry refrigerant, said horizontal tubes being parallel and spaced apart and arranged in vertical rows, a tube for each of the vertical rows of refrigerant tubes passing through the fins, said tube being provided with an electrical heating element adapted to be energized to defrost the coils, said tube and said heating element being positioned below and in proximity to the bottom tube of the vertical row of tubes thereby facilitating rapid defrosting of the coil by simultaneously heating the inner and the outer surfaces of the frost, said outer surface of the frost being heated directly by the convection of heat generated by the said heating element, said inner surface of the frost being heated by circulation of heated refrigerant through the tubes in the vertical row.

3. A cooling unit comprising, an insulated casing, an air inlet in one of the walls of the casing, an air outlet, shutters closing said inlet and outlet and arranged to be opened by a flow of air therethrough, a refrigerating coil positioned upright in the casing, a fan arranged to move air through the casing and over the refrigerating coil, said refrigerating coil consisting of fins and a plurality of tubes for carrying refrigerant, said tubes being parallel and spaced apart and arranged in vertical rows, and a tube beneath each of said rows passing through the fins that is provided with an electrical heating element, said fan being inoperative during the defrosting period thereby permitting the shutters to close and isolate the cooling unit from the atmosphere tobe cooled, said heating element being operative during the defrosting period and being arranged to facilitate ready defrosting of the coil by simultaneously heating the inner and the outer surfaces of the frost, said outer surface of the frost being heated directly by the convection of heat generated by the heating element, said inner surface of the frost being heated by circulation of heated refrigerant through the tubes in the vertical row.

4. A cooling unit comprising, an insulated casing, an air inlet in one of the walls of the casing, an air outlet in the opposite wall of said casing, shutters closing said inlet and outlet and arranged to be opened by a fiow of air therethrough, a refrigerating coil between the inlet and outlet, a fan for moving air through the casing and across the refrigerating coil, said refrigerating coil being provided with fins and tubes passing horizontally therethrough in vertical rows, a tube beneath each of said rows passing through the fins and provided with an electrical heating element, a shut-oil valve in the ,outlet of said refrigerating coil and a by-pass valve around said shut-off valve arranged to operate at a predetermined pressure or temperature to relieve the pressure within the coil if the shut-oil! valve is closed.

CAESAR D. MARLO.

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