US2958208A - Control for a refrigeration system - Google Patents

Description

1960 R. s. BRADEN CONTROL FOR A REFRIGERATION SYSTEM 3 Sheets-Sheet 1 Filed Jan. 31, 1957 j M .7 z i w ,W h a I, g m h 1 M M i m 4 A m U 4 M 2 4 Q w/ fi. M 5 Z 5 r 4 .M 4 t m M J 4 a 7 Nov. 1, 1960 R. s. BRADEN CONTROL FOR A REFRIGERATION SYSTEM 3 Sheets-Sheet 2 Filed Jan. 31, 1957 INVENTOR.

IT70X/VE/Sf Nov. 1, 1960 R. s. BRADEN 2,958,203

CONTROL FOR A REFRIGERATION SYSTEM Filed Jan. 31, 1957 3 Sheets-Sheet 3 INVENTOR.

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CONTROL FOR A REFRIGERATION SYSTEM Ralph S. Braden, Dayton, Ohio, assignor to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware Filed Jan. 31, 1957, Ser. No. 637,410

1 Claim. (Cl. 62181) This invention relates to a control for a refrigeration system and more particularly to apparatus operable to throttle the flow of air over an air cooled condenser in response to variations in the condition of the refrigerant in the system.

Heretofore, some difiiculties have been encountered during mild weather with some refrigeration systems employing air cooled condensing apparatus. These difficulties occur when the condensing temperatures become lower than normal due to cool outside air temperatures. This causes the pressure of. the refrigerant in the condenser to be of low magnitude and there is then an insufficient pressure differential across the expansion valve to force an adequate amount of refrigerantthrough the valve into the evaporator. With an insufficient amount of refrigerant in the evaporator the amount of refrigerant which is boiled off in the evaporator is inadequate which results in a low suction pressure of the refrigerant entering the compressor. Some refrigeration systems rely upon the passage of such suction refrigerant over the windings of the electric motor driving the compressor to cool this electric motor and such systems frequently employ a safety control device to stop the compressor motor when the cooling is inadequate. Safety control devices of this type generally require manual operation of a reset switch to restart the compressor. Thus, it is found that when the suction pressure of the refrigerant entering the compressor is low the cooling of the compressor is unsatisfactory and the compressor motor is stopped by the above mentioned safety control device and it is necessary to manually operate the reset switch to restart the compressor. This results in an undesirable nurn er of inconvenient shut downs of the compressor during mild or cool weather and it is an object of this invention to eliminate these shut downs and correct the conditions which cause them by providing damper means to restrict the flow of air over the condenser under conditions which would otherwise provide excessive cooling of the refrigerant in the condenser.

It is also an object of this invention to variably restrict the air fiow across the condenser in response to variations in the pressure of the refrigerant on the discharge side of the compressor as the pressure of this refrigerant reflects variations in its temperature and by permitting substantially unobstructed flow of air across the condenser when the refrigerant head pressure is too high and throttling the air flow when the head pressure is too low the refrigerant suction pressure which cools the compressor motor is indirectly controlled and the motor cooling is held within adequate limits.

In the drawings:

'Fig. l is a diagrammatic view, partly in section, of a typical residential heating and air conditioning unit of the air cooled type showing my invention applied thereto;

Fig. 2 is a plan view of the condensing unit with its top cover removed;

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Fig. 3 is a vertical section taken on the line 33 of Fig. 2 through the condensing unit;

Fig. 4 is an end elevation of the condensing unit taken on the line 44 of Fig. 3;

Fig. 5 is an end view, partly in section, taken on the line 5-5 of Fig. 4; and

Fig. 6 is a horizontal section taken on the line 6-6 of Fig. 4.

In Fig. '1 a typical residential installation is illustrated as including a furnace 10 installed in a room 12, such as a basement of a residence, and having a cold air return duct 14, a blower 16, a heat exchanger 18 and an air delivery duct 20. -An evaporator coil 22 is mounted in the duct 20 to cool air forced by blower 16 through duct 20 for delivery to remote parts of the residence. According to common practice the furnace 10 is used to heat the residence during some seasons while the evaporator 22 is relied on to cool the residence during other sasons. My invention relates only to a refrigeration system of which the evaporator 22 forms one element denser coils travels through tube 26 and a branch 42 thereof, leading fromcoil 34, to the evaporator 22 and its associated expansion valve, which is not shown. The refrigerant, after passing through the evaporator coil 22, returns to the condensing unit 28 through suction tube 24 and enters the top of the compressor through a fitting 44-. The refrigerant then passes down over an electrtic motor 46, which forms a part of the hermetic compressor 30, and serves to cool this motor. The refrigerant then passes through a passage 43 and other internal passages to a plurality of cylinders 50 where it is compressed and discharged to the pipe 35. Suction gas cooling of compressor motors is a common practice and I do not claim to have deviated from general practice in the construction of the compressor, per se.

in accordance with general practice a low pressure control switch 52 is provided to stop the electrtic motor 46 whenever the suction pressure of refrigerant in line 24 falls below a desired level. trol 52 to fitting 44. Similarly a high pressure control '56 is provided to stop the electrtic motor 46 whenever the discharge pressure exceeds predetermined limits and this control is connected to fitting 37 by tube 58. A thermostat 60 is also provided with a control switch 62 to interrupt the operation of the electric motor 46 and a manual reset button 64 is provided to restart the compressor after it has been stopped by switch controls 52 or 56. These controls follow generally accepted practice and do not, in themselves, constitute a deviation from common commercially available constructions.

The blower 32 and condenser coils 34 and 36 are separated from the compressor 30 by a partition 66 which extends transversely of the condensing unit 28. An electric motor 68, by means of a belt 70, drives the blower 32 to induce a fiow of air inwardly through each of the condenser coils 34 and 36. The air then is forced out an opening 72 provided in the end of the condensing unit 28.

In order to control the flow of air over the condensing coils I provide a plurality of dampers or vanes 74 in registry with the opening 72. The dampers 74 each carry a pair of pins 76 which are pivotally mounted on a sup- A tube 54 connects con-- porting frame structure 78 having a central opening 80. The individual dampers 74 are interconnected for operation in unison by a bar 82 having a plurality of pivotally mounted arms 84 respectively connected to individual dampers 74. r

Means are provided to move the dampers to' selected positions or stations by moving one damper, such as the lowermost damper, and by means of bar 82 the other dampers follow the one moved damper. A piston 86 is reciprocally mounted in a hollow cylinder 88 and provided with a piston rod 90 which penetrates the bottom end of cylinder 88 and is adapted to move with piston 86. The piston 86 is urged in an upward direction by a spring 92 which is contained within cylinder 88 and a bellows 94 encompasses the piston rod 90 and has its upper end sealed to the under side of piston 86 and its lower end 97 sealed to the lower end of cylinder 88. A cavity 96 for the reception of refrigerant under pressure is thus defined within cylinder 88 in the space above piston 86 and below a top 98 provided on cylinder 88 and in the space surrounding bellows 94. The piston 86 is provided with a plurality of peripheral openings 100 interconnecting the above-mentioned spaces which cooperate to define cavity 96. The piston rod 90 carries a bifurcated member 102 which straddles a pivot 104 carried by an arm 106 keyed to one of the pins 76 of the lowermost damper 74. It will be evident that downward movement of piston 86 in Fig. will lower pin 104 and rotate arm 106 and the dampers. The dampers will achieve a more nearly horizontal or open position when piston 86 is moved downwardly.

In order to control the positioning of piston 86 and dampers 74 a refrigerant line 108 extends from the top of cylinder 88 to the fitting 37 which receives high pressure refrigerant from compressor 30. The line 108 is in fluid flow communication with the cavity 96 in cylinder 88. Thus the higher the discharge pressure of refrigerant being delivered by compressor to condensers 34 and 36 the greater the pressure forcing piston 86 downwardly in opposition to spring 92 and the more open the position assumed by dampers 74. The dampers 74 are shown completely open in Fig. 3 and completely closed in Fig. 5.

I claim:

'In a refrigeration system the combination of a compressor driven by an electric motor hermetically sealed in a housing with said compressor, an air cooled condenser and blower means for creating a circulation of air thereover to cool it, an evaporator, a discharge line connecting said compressor'with said condenser, a suction line connecting said evaporator with said housing and operable to dump refrigerant into the interior of said housing to pass such refrigerant over said electric motor to cool it and to supply such refrigerant to said compressor, control means operable to stop said electric motor when the cooling effect of such refrigerant on said electric motor is inadequate, refrigerant pressure regulating apparatus associated with said air cooled condenser and comprising damper means to restrict the air circulation over said condenser, said damper means being operable to variably restrict such flow of air in response to movement of said damper means to a plurality of selective stations, and refrigerant pressure responsive motor means operably connected to said damper means to position said damper means at said stations, said motor means being solely responsive to refrigerant pressure on the discharge side of said compressor.

References Cited in the file of this patent UNITED STATES PATENTS 1,838,259 Hull Dec. 29, 1931 2,210,325 Newton Aug. 6, 1940 2,214,103 Dickey Sept. 10, 1940 2,283,025 Wolfert May 12, 1942 a. I man-

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