US3122895A - Condenser fan control for refrigeration system - Google Patents

Description

March 3, 1964 N. w. WOODS 3,122,895

CONDENSER FAN CONTROL FOR REFRIGERATION SYSTEM Filed Jan. 8, 1962 3 Sheets-Sheet 1 INVENTOR. NORMA/V W. woods March 3, 1964 N. w. WOODS CONDENSER FAN CONTROL FOR REFRIGERATION SYSTEM 3 Shets-Sheet 2 Filed Jan. 8, 1962 O INVENTOR.

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ATTOR/VEXS' Ma rch 3, 1 9 N. w. wooDs CONDENSER FAN CONTROL FOR REFRIGERATION SYSTEM 3 Sheets-Sheet 3 Filed Jan. 8, 1962 INVENTOR.

NORMAN w. woaas United States Patent 3,1225% CGNDENSER FAY QQNTRGL FGR REFRlGERATlGN SYSTEM Norman W. Woods, llrantforrl, Qatar-lo, (Ianada, assignor to Keeprite Products Limited, Brantford, Gntario,

Canada, a corporation of Qntario, Canada Filed Ian. 8, 1962, Ser. No. 164,822 14 Claims. (til. 62-134) This invention relates to a refrigeration system and more particularly to a means for controlling the operation of the cooling fan for an air cooled condenser of a refrigerating unit.

In refri erating systems wherein the condenser is located outdoors and cooled by a fan, when the ambient outdoor temperature drops to a relatively low value in the winter, below freezing, for example, the pressure in 'the condenser may drop to such a low value that the pressure differential between the high and low sides of the system is lower than necessary to produce efiicient operation.

It is therefore an object of this invention to provide a device for controlling the operation of the cooling fan for the condenser so as to insure an adequate pressure differential between the low and high sides of the system.

More specifically, the invention contemplates a clutch interposed between the motor driven shaft and the fan propeller shaft, the clutch being responsive to the pressure of the refrigerant at the condenser for coupling and uncoupling the motor and fan shafts so that when the refrigerant pressure at the condenser falls below a predetermined value, the fan propeller shaft is disconnected from the motor driven shaft. The clutch incorporates a plurality of friction discs for effecting a driving connection between the motor driven shaft the fan propeller shaft, there bein' means provided for maintaining a thin film of oil between the discs so that the extent of slippage between the discs, and therefore the relative speeds of the motor driven shaft and the fan propellor shaft, vary in accordance with the force with which the discs are squeezed together.

In the drawings:

P16. 1 is a generally diagrammatic of a refrigeration system embodying the present invention.

FIG. 2 is a view of a condenser and fan unit showing a modified form of actuatin means for the clutch.

Fit}. 3 is a longitudinal sectional view of the clutch.

FIG. 4 is a vi w along the line 4-4 in FIG. 3.

FIG. 5 is a view along the line 5-5 in FIG. 3.

FIG. 6 is a View along the line 6-6 in FIG. 3.

Referring to the drawings, and particularly Fit 1, a conventional refrigeration system is there shown comprising a compressor 16 connected by a conduit 12 with a condenser i l. The condenser in turn is connected by means of a check valve controlled conduit 16 with a receiver 1S. Receiver 13 connects with evaporator 2%) through a conduit 22 in which there is arranged an expansion valve or equivalent device 24. The outlet of evaporator 2i) connects with the inlet of compressor it by a conduit 2s. A check valve controlled bypass line 23 is illustrated extending between the condenser inlet line 12 and the outlet line 16. The present invention is concerned primarily with the manner in which the condenser 14 is cooled. As illustrated, condenser 14 is enclosed within a housing 3%? having a circular opening 32 therein in which is located a fan 34. Fan 34 is driven from a motor 35 through a belt drive 3% to a clutch The actuation of clutch ll}, as will be explained in detail hereinafter, is controlled by the pressure of the refrigerant in condenser 14. In the embodiment illustrated in FIG. 1, a conduit 42 extends between clutch 4i; and condenser 14. In this arrangement, the refrigerant in condenser 14 actually conrnt a es with cl tch ii In the embodiment illustrated in FIG. 2, a conduit 44 likewise extends from the clutch but instead of connecting directly with condenser 14, conduit has a bulb 46 at the end thereof located in housing closely adjacent the condenser 14. Conduit 44 and bulb 46 may be filled with the same refrigerant used in the system or another expansible fluid if desired. In any event, bulb as is located in housing 3% sufficiently close to condenser 14 so that variations in the temperature of the condenser resulting from a change in pressure in the condenser will produce a change in temperature, and therefore a change in pressure, of the fluid in conduit and bulb 46.

Referrin to P16. 3, the specific clutch utilized in the arrangement illustrated in FIGS. 1 and 2 is illustrated. The clutch includes a housing 48 having an open end closed by a cover plate 59 which is secured in place by screws 52. Cover plate has a fitting 54 threaded thereon. The conduit or 4- connects with fitting 54. On the inner side of the cover plate, there is provided a recess 56 which cooperates with a flexible diaphragm 55s to form a chamber communicating with the fluid line 42 or 44, as the case may be. Around its periphery, diaphragm 56 is supported on one side by the cover plate 59 and on the opposite side by a ring fill. The cover plate and diaphragm assembly is sealed on the end of housing 45 by means of a gasket A pusher plate 64 bears against the portion of diaphragm 5:8 opposite the recess 55 in cover plate 52.. Flats 6 has a bushing as thereon into which is threaded a shaft 68. Shaft 68 extends through a thrust plate 7i fixed within housing 4 1% and has a spring '72 in the end thereof which bears against a thrust bearing retainer i I. Bearing retainer id is provided with a pair of dowel pins 735 which extend through openings 8 in thrust plate 7% A compression spring 30 around shaft has one end bearing against thrust plate 7% and its other end bearing against an adjusting nut 82 which is threaded on shaft By threading adjusting nut 32 along shaft as, the force with which the pusher plate 64 bears against diaphragm 58 may be adjusted.

The opposite end of housing 43 is reduced as at 84 and is fashioned with seats for bearings 06 in which a shaft 83 is journalled. The portion of shaft 83 projecting out of the reduced end 84 of housing 4 is fashioned with a keyway slot 9-9 for retaining a pulley 92 thereon (FIG. 1). Pulley Z is driven through motor 36 through the belt drive 33. Within shaft 8%, there is arranged a second shaft 9 Fan is mounted on shaft 94. Shaft 94 is supported adjacent the outer end of shaft 83 by bearings 96 and adjacent its inner end, it is supported by hearing 93. The inner end of shaft is bell-shaped so as to form a generally cylindrical cavity ran through which the inner end of shaft 94 projects axially. A plurality of friction discs 1% 13 are alternately arranged on the inner end of shaft 9%. Friction discs ltl i are mounted to rotate with shaft 94 by means of a key 166. On the other hand, friction discs Hi2 are mounted to rotate with shaft 88 by means of a key 1%. It will be noted that the keys and 1% enable the clutch discs to shift axially of shaft 94 and the bell-shaped end of shaft 83. These friction discs are retained in place by means of a clutch plate lit and a not 112 threaded on end of shaft 94. A thrust bearing lid is 10- tne inner cated between clutch plate lid and retainer '74.

In use, the interior of the housing 48 is filled with oil. Thus, seals are provided at 116 and 3.18 to prevent oil from leaking out of housing. In accordance with this invention, it is desired to maintain at least a thin film of oil between the adjacent friction discs 1&2, 1 5 Accordingly, each of the discs keyed to the inner shaft 94 are formed on opposite sides thereof with grooves 129. Grooves 12% extend in an arcuate path from the inner per square inch, the discs to the outer periphery of these discs. Likewise, clutch plate 110 is formed with similar grooves 1'22. The inner 'end of shaft 94 is provided with. a plurality of axially extending passageways 124 which extend radially to the surface thereof as at 126 along that portion of the shaft on which the friction discs 1 52, 164 are mounted. When shafts 88 and 94 rotate, it will be appreciated that oil from passageways 124 is directed outwardly between the successive friction discs 182, 164 through the radially extending grooves 120 to provide lubrication between discs 102, 104. These friction discs can be formed of the same material such as steel or of different materials. Friction discs 104 are preferably formed from heat treated cold rolled low carbon steel plate and friction discs 192 are preferably formed from a heat treated alloy steel such as molybdenum steel. The notches 128 at the outer periphery of discs 102 provide axial passageways along the stack of discs for the oil directed radially outwardly through grooves 126.

It will be appreciated that in some installations, fan 34 might be mounted for rotation about a vertical axis in which case clutch 46 would be mounted with its long axis extending vertically. To assist lubrication of shaft 94 for such installations, a spiral oil groove 13%? is formed around shaft 94 so that it extends from hearing $3 to the portion of the shaft surrounded by bearings 96. An

oil wick 132 is located between shafts 94 and 38 to facilitate such lubrication.

As'explained previously the pressure of the fluid at the fitting 54 of clutch 4t varies in accordance with the pressure of, the refrigerant in the condenser. In the embodiment illustrated in FIG. 1, this is true because the conduit 42 extends directly from the condenser to fitting 54. In the embodiment illustrated in FIG. 2, the pressure of the fluid at fitting 5d varies in accordance with the pressure of the refrigerant in the condenser because the bulb 46 is located adjacent the condenser and the temperature thereof varies generally in accordance with the temperature of the condenser. In any event, when there is a rise in pressure in the condenser, there will be a rise in the pressure of the fluid in diaphragm chamber 56. The pressure of the fluid in diaphragm chamber 56, it will be noted, urges the pressure plate '64 an shaft 65 ina direction to the right as illustrated in PEG. 3, opposing the action of spring 86. The fluid pressure in chamber 56 is exerted against the stack of friction discs 162, 1594 on shaft 94 so as to compress the stack and tend to establish a driving connection between the successive discs. Thus,

' sures'at which it is desired to effect a coupling and uncoupling of the motor drivenshaft 38 and the fan prope lor sha ft 94. V a V -With thearrangement i lustratec and using a particular refrigerant nut 82 can be adjusted so that at a predetermined pressure of the refrigerant the condenser, say

' 110 lbsper square inch,'the fluid pressure in chamber 136 willbesuflicient to partially overcome the bias of spring 89 and apply suflicient force to the stack of discs 1G2, 104 on shaft 94 to establish at least a slipping driving connection between shafts 88 and 9 Thus, shaft 4 on which the fan 34 is mounted will be driven at a speed somewhat less than the speed to which shaft 3-5 is driven by motor as. As the pressure in the condenser rises, the differential speed between shaftsiSS and 94 will'diminish so that at a predetermined higher pressure, say 136 lbs. 132, 164 will be effectively locked together and the two shafts will rotate at the same speed. By the same token, when the pressure in the condenser falls below a predetermined value, a slippage will occur between the successive friction discs 192, 194 and the speed of the fan shaft 9-4 will progressively diminish as the pressure in the condenser falls until a point is reached where the fan will stop or, depending upon the design of the clutch, will rotate at a minimum speed because of residual fluid or frictional drive.

The grooves 120 in the friction discs assure a constant flow of oil between the successive discs as well as a continual wiping action. This is desirable for several reasons. In the first place, a thin film of oil between these discs will prevent the discs from squealing when they rotate re.ative to one another. Furthermore, the provision of a thin film of oil between successive discs enables the discs to slip past one another a variable extent so that within a predetermined range of pressure change in the condenser, the speed of rotation of fan as varies generally in accordance with the pressure of the refrigerant in the condenser.

Thus, with the arrangement disclosed herein, when the outside ambient temperature drops to a value such that the cooling action of the rotating fan on the condenser would produce too low a pressure differential between the high and low sides of the system, operation of the fan is automatically cut off until such time as the pressure in the condenser rises to a value wherein operation of the fan is desired. Likewise, it will be appreciated that in view of the fact that the degree of slippage between the adjacent friction discs 192, 1.64 over a predetermined range, varies generally in accordance with the change in pressure in the condenser, the fan will be driven at a variable speed in accordance with the operating conditions and requirements of the refrigeration system.

I claim:

1. In a refrigeration system of the type comprising a compressor, an evaporator, a condenser connected between the compressor and evaporator, a fan for directing air over the condenser, and a motor for operating said fan, the combination of a shaft driven by said motor, a separate shaft for propelling said fan, a fluid pressure operated clutch for coupling and uncoupling said shafts, a fluid line connected withsaid clutch for controlling the operat on of the clutch and means for causing the pressure in said fluid line to vary in accordance with the 'variation of the pressure of the refrigerant in said condenser. V

2. The combination called for in claim 1 wherein said fluid line extends to and connects with said condenser.

3. The combination called for in claim 1 wherein said fluid line is provided with a temperature responsive bulb disposed directly adjacent the condenser such that the temperature of said bulb and consequently, the pressure of the fluid in said fluide line is responsive to the pressure of the refrigerant in said condenser.

4. The combination called for in claim 1 wherein said 7 clutch includes a plurality of adjacently positioned fric tion' discs, the successive discs being connected ,to'rotate one with the motor shaft and the other with the fan-shaft,

means for directing the pressure of the fluid in'said fluid line to squeeze the discs together whereby the degree'of slippage between successive discs pressure in said fluid line;

5. The combination called for iniclairn. 4 including. means opposing the action of said fluid pressure on said discs,*said means being adjustable to permitvariation of the pressure in said fluid line necessary to effect couclutch for controlling the operation of, a' condenser cool ing fan response to the pressure of the refrigerant:

in the condenser comprising a housing, a motor driven? V shaft, a fan driving, shaft, said shafts being telescoped' is responsive to the V 7 V one Within the other and journalled for rotation in the housing, said shafts projecting out of the housing at one end, one of said shafts being adapted to be motor driven and the other being adapted to rotate the condenser cooling fan, the inner shaft being journalled for rotation within the outer shaft, a plurality of adjacently positioned discs, the successive discs being connected one with the inner shaft and the next with the outer shaft, 21 fluid line connected with said housing, means for transferring the pressure of the fluid in said line axially against said stack of discs whereby to vary the frictional drag between the discs and means for causing the pressure in said fluid line to vary in accordance with variation in the pressure of the refrigerant in said condenser.

8. The combination called for in claim 7 wherein said housing comprises an oil reservoir and said discs are fashioned with radially extending grooves thereonfor directing oil between the adjacent faces of the successive discs.

9. The combination called for in claim 7 wherein said means for transferring the pressure of the fluid in said fluid line to said stack of discs comprises a diaphragm in said housing which is adapted to flex in response to variations of the pressure in said fluid line, and a shaft extending axially between said diaphragm and said stack of discs.

10. In a refrigeration system, a fluid pressure operated clutch for controlling the operation of a condenser cooling fan in response to the pressure of the refrigerant in the condenser comprising a housing, a motor driven shaft, a fan driving shaft, said shafts being telescoped one within the other and journalled for rotation in the housing, said shafts projecting out of the housing at one end, one of said shafts being adapted to be motor driven and the other being adapted to rotate the condenser cooling fan, the inner shaft being journalled for rotation within the outer shaft, a plurality of adjacently positioned discs, the successive discs being connected one with the inner shaft and the next with the outer shaft, a fluid line connected with said housing, means in said housing including a flexible diaphragm forming a chamber communicating with said fluid line, a shaft extending between said diaphragm and said stacks of discs, said shaft being effective to apply a force tending to squeeze the discs together in response to the pressure in said chamber, means biasing said shaft in a direction opposing the action of the diaphragm and means for causing the pressure in said fluid line to vary in accordance with variations in pressure of the refrigerant in said condenser.

11. The combination set forth in claim 10 wherein said biasing means comprising a spring, said spring having one end engag ng a fixed abutment in said housing, the opposite end of the spring engaging an abutment on said shaft, said abutments being relatively adjustable axially of the shaft to vary the bias of said spring.

12. The combination set forth in claim 10 including a thrust bearing interposed between said stack of discs and the adjacent end of said shaft.

13. The combination cal'ed for in claim 10 wherein said housing comprises an oil reservoir encompassing said discs, said discs having grooves thereon extending radially from the inner to the outer peripheries of the discs for conducting oil radially between the discs.

14. In a refrigeration system, a fluid pressure operated clutch for controlling the operation of a condenser cooling fan in response to the pressure of the refrigerant in the condenser comprising a housing, a motor driven shaft, a fan driving shaft, said shafts being telescoped for rotation one within the other and journalled for rotation in the housing, said shafts projecting out of the housing at one end, one of said shafts being adapted to be motor driven and the other being adapted to rotate the condenser cooling fan, the inner end of the outer shaft being generally bell-shaped to form a cylindrical recess surrounding the inner end of the inner shaft, a stack of friction discs in said recess, said friction discs being keyed one with the inner shaft and the next successive one with the bell-shaped end of the outer shaft, a fluid pressure line extending from the condenser to said housing, a mechanism within the housing for applying the pressure of the fluid in said fluid line axially against said stack of discs and means biasing said mechanism in opposition to the action of the pressure in said fluid line, said bias means being adjustable to thereby vary the pressure in said fluid line eflective to provide a driving connection between the discs.

References Cited in the file of this patent UNITED STATES PATENTS 1,894,285 Swezey Jan. 17, 1933 2,587,230 Schaad Feb. 26, 1952 2,588,495 Dodge Mar. 11, 1952 2,877,751 Johnston Mar. 17, 1959 2,891,644 Davis June 23, 1959 2,952,991 Pierre Sept. 20, 1960 2,971,347 Gygax Feb. 14, 1961

Claims (1)

1. IN A REFRIGERATION SYSTEM OF THE TYPE COMPRISING A COMPRESSOR, AN EVAPORATOR, A CONDENSER CONNECTED BETWEEN THE COMPRESSOR AND EVAPORATOR, A FAN FOR DIRECTING AIR OVER THE CONDENSER, AND A MOTOR FOR OPERATING SAID FAN, THE COMBINATION OF A SHAFT DRIVEN BY SAID MOTOR, A SEPARATE SHAFT FOR PROPELLING SAID FAN, A FLUID PRESSURE OPERATED CLUTCH FOR COUPLING AND UNCOUPLING SAID SHAFTS, A FLUID LINE CONNECTED WITH SAID CLUTCH FOR CONTROLLING THE OPERATION OF THE CLUTCH AND MEANS FOR CAUSING THE PRESSURE IN SAID FLUID LINE TO VARY IN ACCORDANCE WITH THE

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