US2844945A

US2844945A - Reversible refrigerating systems

Info

Publication number: US2844945A
Application number: US247239A
Authority: US
Inventors: Muffly Glenn
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-09-19
Filing date: 1951-09-19
Publication date: 1958-07-29
Anticipated expiration: 1975-07-29

Description

, G. MUFFLY REVERSIBLE REFRIGERATING SYSTEMS Jul 29, 1958 5 Sheets-Sheet 1 Filed Sept. 19, 1951 j m E m E DP W 3 x i. w fir K r 5 a .M M W2 w/flw I @L. y

ly 29, 1958 GTMUFFLY 2,844,945

. I REVERSIBLE REFRIGERATING SYSTEMS Filed Sept. 19, 1951 3 Sheets-Sheet 2 July 29, 1958 MUFFLY 2,844,945

REVERSIBLE REFRIGERATING SYSTEMS Filed Sept. 19, 1951 3 Sheets-Sheet 3 INVENTOR. G rr/7 )721 29 2 United States Patent REVERSIBLE REFRIGERATING SYSTEMS Glenn Mufliy, Springfield, Ohio Application September 19, 1951, Serial No. 247,239

22 Claims. (Cl. 62--160) This invention relates to defrosting and to reversing the direction of fluid flow with or without the direction of compressor rotation being reversed.

There is a need for a reversible compressor and/or valve mechanism in reverse-cycle refrigerating and air conditioning systems, and particularly for defrosting freezer evaporators of two-temperature refrigerators.

No refrigeration compressor now on the market is suitable for reversing refrigerant flow, hence complicated valve arrangements are coming into use. Piston type compressors continue to pump in the same direction when their direction of rotation is reversed. Rotary compressors in which the piston or rotor is carried'by' a crank pin or eccentric require discharge valves which prevent operation of the compressor in reverse. The gear or lobed impeller type of compressor reverses its directionof fluid flow when the direction of rotation is reversed, but this type has not proven satisfactory and is not currently in production in the refrigeration field because of .noise and the fact that gas leakage increases with Wear. The type of rotary compressor in which a rotor is eccentrically located with respect to its cylinder and mounted concentrically on the drive shaft usually carries one or more sliding radial vanes which sweep the clearance space. This latter type of compressor does reverse its direction of pumping when reversed in rotation if equipped with three or more vanes, but such reverse pumping isinefiicient since the suction and dis.- charge ports are not suited for reversing their functions. When four or more radial vanes are carried by the rotor it is practical to dispense with the usual check valves located in the inlet and'discharge ports, but for best results the discharge port should be smaller than the suction port and the latter should extend farther around the cylinder in order to allow proper filling of the displacement space. This has prevented the development of a satisfactory reversible compressor.

It is an object of this invention to provide a compressor which reverses its direction of pumping when its direction of. rotation is reversed and has good efliciency when operated in either direction.

Another object is to provide a compressor having a pair of ports which interchange their functions of inlet and discharge when the compressor rotation is' reversed and to provide an additional port which serves as an auxiliary inlet port for both directions of rotation.

Another object is to provide self-actuating valve means for connecting the last mentioned port with the suction conduit and shifting this connection to another suction conduit when the compressor rotation is reversed.

Another object is to provide a compressor which allows high and low side pressures to equalize when idle.

Another object is to provide a valve mechanism responsive to the starting of the compressor in either of two manners to close and open the proper ports in relationship to the direction in which the compressor has been started.

ICC

of a freezer evaporator'ina primary system which is combined with a secondary system of which the evaporator is not to be defrosted. 4

Another object-is to providea pair of opposed check valves so interconnected as to cause the closing of one valve" to open the other when the system is started and to allow each valvetoa'ssume a' partly open position eachtime the compressor is stopped.

Another object-is to provide a'check valve and its associat'ed chamber so proportioned that when the valve is in its idle partly open'position it nearly closes the passage so that a slight'flow of fluid will cause the check valve to close, yet when the valve is fully opened it offers no serious obstruction to the How of fluid in the direction which would otherwise tend to close the valve.

Another object-is. to provide for defrosting the colder evaporator only in a multiple temperature system using either a'con'ventio'nal compressor or a compressor with the multiple-eifect'or dual-suction arrangement which provides two distinctsuction pressures.

Still another object is to achieve the utmost simplicity in a two-temperature system with automatic defrosting of the colder evaporator, such defrostingbeing accomplished automatically by a simple reversal of motor rotation or shifting of valves without aifecting the temperature of the space cooled by the warmer evaporator.

In the drawings; v

Fig. '1. is aldiagr'ammatic view of a two-temperature refrigerating system employing a new type of compressor and valve mechanism which combine to reverse flow in the system. Fig. 2 is a'longitudinal'j sectional view of a compressor such as illustrated diagrammatically in ,Fig. 1, showing the preferred arrangement of ports.

Fig. 3 is a sectional and diagrammatic view of a similar compressor as used in a heat-pumpor reverse-cycle system with the reversing valve incorporated ii the motor-compressor unit and arranged to control vapor flow instead ofliriuid. flow.

Fig. 4 is atop view of .a reversing valve mounted on the head. of a conventional compressor, to provide reversal .of both, discharge and suction where the compressor does not initself're'verse flow when its direction of rotation is reversed.

F Fig. 5 is a detail sectional. view on the line 5-5 of Fig.6 is .a diagrammatic view of 'a system similar to Fig. 1 but. using a reciprocating multiple-effect compressor'andia clock switch tocontrol the valves.

Fig. 7 is a diagrammaticview of. a similar system but using a conventional compressor and having the electricaliy'actuated" valves. under thermal instead of clockcontro Fig. -8 isa bottom-view of a sealed motor-compressor unit designed for use in .a system having its high side on the rear wall .of .atwo-zone refrigerator to conserve space and aid in disposalofde frost water.

Fig. 1 shows the compressor 10 drivenclockwise, which is the direction of rotation for defrosting the freezer evaporator 12. with. hot highpressure refrigerant vapor, which condenses therein and flows through the restrictor tube .14 to the condenser. 1.6,.in which the condensed refrigerant evaporates, and returns to the compressor at' 3 24 of the compressor during a considerable portion if not all of the short defrosting period of the freezer evaporator 12. The rotation of rotor 26 of the compressor and the path of refrigerant flow during this defrosting period are indicated by solid arrows.

At the completion of the defrosting operation the compressor rotation stops and then restarts in the opposite direction as indicated by the dotted arrow on the rotor 26. This causes the port 28 to serve as a suction inlet to the compressor, which draws refrigerant vapor from the freezer evaporator 12 and discharges it at port 18 through the tube 30 to the condenser 16. Liquefied refrigerant flows from the condenser through the vaporlock restrictor 14 to the chamber 32 of the reversing valve 34. The impact of the resulting jet of liquid refrigerant mixed with its flash gas striking the vane 36 causes this vane to tilt upon its pivot 38, opening the valve 22 and closing the valve 40. Liquid refrigerant now leaves the chamber 32 by way of the tubes 42 and 44 after filling the lower portion of the chamber 32 with liquid. When a sufiicient pressure has developed within the tube 42 in excess of the pressure existing in the freezer evaporator 12 the weighted check valve 46 lifts terbore 65 connected with all of the slots by means of radial holes, which are indicated by dotted lines.

When the motor is stopped with a considerable pressure difference existing between the

tubes

30 and 50 the compressor is free to reverse its direction of rotation and act as a vapor-expansion motor until these pressures are nearly balanced. It is desired that pressures within the system equalize during idle periods of the compressor and the tendency of the compressor to act as a motor aids the electric motor in starting its reverse rotation when the controls of the system cause an instantaneous switch from cooling to defrosting or viceversa.

The housing 66 which encloses the weighted check valve 46 may be incorporated with the valve assembly 34 to eliminate the tubes which connect these two housings, but it may be preferred to keep them separate so that the housing 66 can be located adjacent to the colder evaporator 12 while the valve assembly 34 is located adjacent to the warmer evaporator 20. In either case it is preferred that and refrigerant liquid flows through the tube 48 into the lower temperature evaporator 12, from which vapor flows through the tube 50 to the inlet port 28 of the compressor.

It will be noted that the spacing of the

ports

28 and 24 is such that they are always divided by one or more of the radial vanes 52,54, 56, and 58 so that vapor withdrawn from the evaporator 12 is trapped in the space between two vanes, such as 52 and 54, before this space comes into communication with the auxiliary inlet port 24, at which time higher pressure suction vapor from the evaporator 20 fiows into the space between these two vanes. This space reaches its maximum expansion at the time the two vanes reach their symmetrical position straddling the port 24, but due to the velocity of suction vapor in the tube 60 it will continue to flow from tube 60 into the compressor until approximately the cut-off point at which the vane 54 cuts the compression space off from the auxiliary inlet port 24.

The trapped vapor is now compressed and delivered to the port 18, such discharge continuing until the vane 54 opens the port 18 to the next compression space be tween the vane 54 and the vane 56. There will be some reverse flow between the port 18 and these arcuate spaces, but with the proper arrangement of ports and the proper number of blades there can be no actual leak-back except the limited amount of unavoidable leakage past the working surfaces of the compressor.

The shaft 62 carrying motor. 26 is preferably the shaft of a two-pole alternating current motor which, on 60 cycle current, will operate at about 3400 to 3500 -R. P. M. It is desirable to keep the motor diameter down to a minimum for reasons which will appear later herein, hence in Fig. 1 it is assumed that the rotor and stator of the motor are hidden back of the compressor cylinder 64. The motor and compressor are preferably enclosed within a sealed casing to which the tube 60 leads and from which vapor flows into the port 24. p The cylinder 64 is provided with end plates or heads in the customary manner and it is preferred that the

ports

18, 24 and 28 be formed by recesses in one or both of these heads rather than as shown diagrammatically in the cylinder bore in Fig. l. The blades of rotary compressors are often provided with springs to hold them in engagement with the cylinder bore, but such springs may be omitted in this case because of the high speed of rotation which provides ample centrifugal force to hold the blades against the cylinder bore.

In order to prevent the development of a partial vacuum in the slot back of a blade, which would interfere with the operation of centrifugal force, and to prevent the accumulation of oil in a slot which would interfere with the free movement of a blade, I have shown a counthat the internal volume of the chamber 32 below the level of the various ports be kept at a minimum to conserve refrigerant liquid. All four of the ports connecting with the chamber 32 may be located at the same level, though shown at two different levels in Fig. 1 so that the refrigerant flow paths can be more easily traced. The freezer evaporator 12 may be located either above or below the warmer evaporator 20 and the weighted check valve 46 may be located either above or below the reversing valve assembly 34, hence this system is adaptable for use in a two-Zone refrigerator with the freezer compartment either above or below the main food compartment.

Fig. 1 illustrates the arrangement of ports and refrigerant passages for cooling a pair of evaporators simultaneously, one at a lower evaporating pressure than the other. The condenser 16 receives refrigerant from both evaporators while they are being cooled, but when the colder evaporator 12 is being defrosted by reverse operation of the compressor the warmer evaporator 20 is not affected since it is isolated by the closed valve 22.

A third evaporator 68, comprising a part of a secondary refrigerating system, may be combined with this system by locating the secondary condenser 70 in heat exchange with a portion of the evaporator 12, as indicated in Fig. 1. If a secondary system such as 6870 is used in place of the warmer evaporator 20, or only one evaporator is required, the

valves

34 and 46 may be eliminated, connecting the vapor-lock restrictor 14 directly with tube 48. Such a system is illustrated in Fig. 3. The elimination of evaporator 20 makes the port 24 available for withdrawal of refrigerant vapor from the evaporator 12, but it is then preferred to stop it off from evaporator 12 during the defrosting period, as will be explained later with reference to Fig. 3. The secondary evaporator 68 will not be affected by the defrosting of evaporator 12 since the heating of the secondary condenser 70 merely stops the flow of vapor from 68 to 70, thus trapping the entire charge of secondary refrigerant in the evaporator 68.

Fig. 2 shows a preferred arrangement of the compressor of Fig. l with ports in the

end walls

72 and 74 instead of in the cylinder barrel 64. The auxiliary intake port 24 in the wall 74 is open to the interior of the sealed housing 76 and hence placed at the top to be above the level of oil 78. The suction tube 60 enters the housing on the far side of the motor 80 so that suction vapor from evaporator 20 aids in cooling the motor. The

ports

18 and 28 are formed in the end plate 72 which closes the housing.

Tubes

30 and 50, connected with these ports, are brazed to the end plate 72. An oil slinger 82, shown in the form of a drawn cup attached to the rotor of the motor, has two or more arms 84 which, in either direction of rotation, throw oil against the sheet metal baflle 86 which is attached to the plate 74 and assesarranged to carry oil intothe pocket 88,,which leads to port 24 and' also to the shaft through h L 90 The stator of the motor i's presscdinto the oti ng 76 and provided with a longitud'iiialf o'il passageQZso that the level of oil '78 is maintained on"b'o'th sides of the motor. Four terminals of the motor winding, as 94 of 'Fig. 2, are connectedwith asuitablereversing"switch,,as 96 in Fig 3, which may be operatedmanually" by te'rnperature or pressurechanges, byfcount ofcycles orope'nings of cabinet or by'a clock, for 'tli'epurposeofstarting the motor in either directionof rotation. In one'closed position of switch '96 one of the of the*linernay be connected with wires 97andj98 whileflie other' l'i' "w're is connected with 99 and100i *Iii-the other erased 'o sition of switch 96 one of: the-line wires: westwards be connected with 97' and 9 9 whilethe other linew'v'ire' connects' with 98 and 100 for the reverse rotation ofthe compressor. r

Referring now to-Fig. 3;. which s ows 'a -rotarYcompressor similar to those of previousfigures'wThis compressor is assumed to beof the open type, '.='-e {notinconporated in a sealed unit," and"to be -cotinectcd with two heat exchangers 12 and '16" in series-with the restrictor '14 between them. The'rotor 26-, which is com centric with and driven'by an'electric motor carnies four blades 52, 54, 56 and 5'8:which arefree' to slide 1 their radial slots in the rotor so that theyare held in contact with the bore of cylinder -64"bycentrifugal rforcerwhen ever the compressor is operating; Since there me no springs holding the blades'in contact-with thecylinder bore, there are no check; valves which remain-closed when the compressor is idle and the compressor'may he driven in either direction byexcess pressure intone-of the

lines

30 or 50, it is seen thathigh and low-side pres sures will equalize very soon after thecompressor' is stopped. m In Fig. 3, as in Fig. 1', it-isassumed-zthat low pressure refrigerant vapor is flowing. tothecom'pressor from the tube 30, as indicated by the solid-arrow and that high pressure refrigerant vaporis being discharged-through the tube 50 as indicated by the solit'la'arrowt This means that the rotor is being driven counterclockwise, .assind-i' cated by the solid arrow,-and that thereishigh-tpressurerefrigerant vapor in the tube 1021which-leads to--the1check valve 104. This pressure holds the check -tvalve 1104 closed and thereby through the mediu-mg ofthe-.- rocker 106 the check valve 108 .is held open. Suction ,vapor is thus free to enter the compressor, through thesuction port 24 and by way of: the branch tube.110 and the port 18. Low pressure refrigerant, vaporenters the increasing clearance pocket between adjacenthl-ades and 54; This clearance pocket increases in volume afterpassing out of communication with the first "inletport #18, but soon thereafter it comes into" open" communication with the port 24 which extends a' wnsraemuemgi on each side of the verticallcenter line. Suction vapor willlcontinue to enter the arcuate compression space between blades after this space has started. tofr'edu'ce in volume, but before there is any appreciable'back:iflow ofvapor from the compression sp'ace'girito'ft'he elongated port :24 this port will be cut off by"bla'd'e'5'4. 7 From this point on the compression space decreases 'in'ivolume '"d'sub tially all of the vapor is discharged i After the blade 54 has passed the port *8 t'her'e'will efa return flow of high pressure vap'or into" the 'riext' corn: pression pocket but not 'beyondit. It isfthtiss'eeii 'hat the customary discharge check valve" is no'trehuired in the port 28. The valve 104 will be held firmly" closed-by high pres sure refrigerant vapor as rang as the compressor is operated counterclockwise as indicated by solid rrow n Fig. 3. Due to the arrangementdftiie tubes ands]! it will be seen that'oil is 'centrifiigal'lys'epaiated the discharge vapor tocollect in thef chamber a e" of the closed check valve 104'. This dilrern'a 'ns' so: trapped until the next idle period of the compressor, at which time it willzfiow'i'nto port 24 or port 28 and'reenter the compressor when next started in its reverse direction of rotation.

As' shown in Fig. 3 the valves 104 and 108 are each hinged to 106 and 108 is additionally supported by one of the ears 109 formed on 106, thus the open valve 108 and the rocker 106 exert gravitational forces tendingto open the valve 104,.and their neutral position of rest is with each valve partly opened. It will be seen in Fig. 3 that there is only a small clearance between each valve and the recess which it enters in its neutral position. In the event ofvapor fiow toward the valve 104 from the tube 102 this valve will be pushed closed and the valve 108'pushe'd to its position of maximum opening, thus no matter in which direction the compressor is started the valves 104 and 108 will adjust themselves to the proper relationship which allows suction vapor flow to the port 24 from thelow pressure side of the system and stops flow to port 24'from the high pressure side of the system.

As shown in Fig. 3, with counterclockwise rotation of the'compressor rotor 26, high pressure refrigerant vapor is'being'discharged at the port 28 to the tube 102 which leads upward to the chamber 112, this chamber being stopped off from the port 24 by the valve 104 which is closed, hence the high pressure refrigerant vapor is delivered to the tube 50 which leads to the heat exchanger 12 now serving as the condenser of the system. Condensed refrigerant fiows through the restrictor 14 to the heat exchanger 16, now serving as an evaporator, and the evaporated .refrigerant returns through the tube 30 to the chamber 114, which is now serving as a suction chamber. The refrigerant vapor is free to flow through the tube 110 to the primary intake port 18 and past the open valve 108 to the secondary intake port 24.

Whenthe compressor is stopped the pressure within the system will substantially equalize due to the open restrictor' 14; to the 'fact that the compressor may be turned in reverse by high pressure vapor from heat exchanger 12 and to the absence of centrifugal force allowing vapor to pass the vanes carried by rotor 26. The weight of the rocker 106 and of the open valve 108 now cause the rocker 106 to drop to its neutral position at which both valves 1 04 and 108 are open. In this neutral position each valve enters its counterbore 116 where it offers considerable resistance to vapor flow without closing tightly.

Assuming now that the compressor is started in the direction of rotation indicated by the dotted arrow on the rotor 26, either by reversing the motor which drives the shaft 62 or by the use of a reversing mechanism between this shaft and its source of power. Thesuddenlyapplied' torque causes the body of the compressor, which is mounted on flexible supports 118, to rotate slightly tothe right at the instant of starting. The rocker 106' and the two valves pivoted thereto will, due to their inertia, 'lag' behind the sudden clockwise jerk of the compressor body thus causing the valve 108 to close while at" the same instant vapor discharged through the port 18 to the tube 110 impinges upon the valve 108 to aid in holding it closed until the pressure within the chain: 136L114 builds up to positively hold the valve-108 closed. This-closing of the valve 108 causes the valve 104 to be 'lifted 'fa rther from its seat and clear ofits counterbore 116 so that suction vapor is now free to flow from the tub 5'0 to the auxiliary intake port 24 as well as to port 28; which now becomes the primary suction port; This: clockwise rotation of the compressor causes'th'e heat exch'a'nger'16 to begin operation as the condenser of the system: Liquid refrigerant now flows to the left through therestrictor 14-as indicated by the dotted arrow and it evaporates in the heat exchanger 12, which now serves as the evaporator of; the system, delivering refrigerant vapor to the tube SO which is noW serving as the suction tube. Suction vapor is free to enter the main suction port f2 8fo1f tlifeconipressor and also to pass the open valve 104 from the chamber 112 to the auxiliary suction port 24.

It is thus seen that the

ports

18 and 28 have exchanged their functions and now serve as discharge and suction ports respectively, whereas the auxiliary suction port 24 continues to operate as the auxiliary suction port, being open to heat exchanger 12 instead of to heat exchanger 16. This use of the auxiliary suction port to receive vapor from the same evaporator from which vapor is flowing to the

active suction port

18 or 28 is suitable for a system of the heat pump type in which reversed operation may continue for several hours instead of for a few minutes as explained in connection with Fig. 1.

Fig. 1 represents the multiple effect use of the compressor and its use for the purpose of defrosting the colder evaporator, whereas in Fig. 3 the same principle is shown as utilized in an air conditioning system of the so-called reverse cycle type, which either heats or cools the room. In the latter case there is no need for two distinct evaporating temperatures and normally neither one of the two heat exchangers collects frost during its operation as the evaporator of the system. In both cases gravity, inertia and pressure differences combine to actuate the valves, the required one being held closed by refrigerant pressure during operation of the compressor in either direction. The valve mechanism 34 of Fig. 1 might be mounted on the compressor or on its casing and actuated by the suddenly applied torque, as explained in connection with Fig. 3, or the valve mechanism of Fig. 3 might be mounted independently of the compressor and operated solely by refrigerant flow, as is the valve 34 of Fig. 1.

Assuming that the compressor of Fig. 3 is incorporated in a sealed unit and rigidly connected with the stator of an electric motor enclosed by the same sealed casing, it will be seen that the direction of the starting jerk applied to the compressor body is now in the opposite direction from that of rotation of the motor rotor, the shaft 62 and the compressor rotor 26, due to the resultant torque being applied through the motor stator to the body of the compressor, with or without transmission of such resultant torque through the casing which encloses the motor and the compressor.

Fig. 4 shows how the principle of actuating a reversing valve by means of inertia can be applied to a conventional piston type compressor to accomplish the result of Fig. 3. Assuming that suitable provisions have been made for lubrication, a reciprocating compressor of the piston type may be driven in either direction of rotation, but the reversal of rotation does not reverse the direction of refrigerant flow. The valve mechanism seen in Fig. 4 is intended to replace the usual cylinder head of an open type reciprocating compressor in which both intake and discharge ports are through the regular valve plate of the compressor. The plan is to design a replacement cylinder head to be bolted on top of the valve plate in place of the original cylinder head which is connected with the suction and discharge tubes, thus converting a conventional rotary or reciprocating compressor into a flowreversing compressor.

The special cylinder head includes the valve body which is shown in section as 130 in Fig. 4. The chamber 132 connects with the chamber into which high pressure vapor flows from the regular discharge valve of the compressor, and the chamber 134 connects in a similar manner with the chamber from which suction vapor is drawn through the regular intake valve of the compressor. It is therefore only necessary to consider Fig. 4 as a top view of a conventional reciprocating compressor of which the crank shaft is indicated at 136. The actual valve mechanism is very similar to the one shown in Fig. 6 of my copending U. S. patent application Serial No. 50,101 filed Sept. 20, 1948, now Patent No. 2,672,016, but the actuating mechanism shown in Figs. 7 and 8 of this earlier patent appli- 8 cation of mine is omitted. The valve stems 138 and 140 are supported by

guides

142 and 144 respectively and'are free to slide therein. We thus have a pair of check valves 146 and 148 in the discharge chamber 132,

but these check valves are rigidly connected together so that one must open when the other is closed. Likewise we have a pair of check valves 150 and 152 arranged to close one or the other of two'ports which lead into the chamber 134 from which suction vapor flows to the regular intake valve of the compressor.

Assume now that the valves are as shown in Fig. 4 or in neutral positions, none being fully closed, that the compressor body is mounted on springs or other flexible supporting means 118, as shown in Fig. 3, and that torque is suddenly applied to the shaft 136 in the direction indicated by the solid arrow. During the first compression stroke of a piston in the compressor the compressor body will jerk suddenly to the right, causing valves 146 and 152 to .close. This compression stroke delivers compressed vapor into the chamber 132, thus holding the valve 146 closed and the valve 148 open so that the discharge vapor can flow freely past valve 148 into the chamber 154 and out through the port 156 which now serves as the discharge connection leading to the condenser. The discharge vapor filling the chamber 154 aids in, holding the valve 152 closed so that the valve 150 is held open, allowing vapor to be drawn from the port 158 through the chamber 160 and past the valve 150 into the chamber 134, which is connected with the regular intake port'of the compressor. So long as the compressor continues to operate in this direction, each of the valves 146 and 152 is held closed by high pressure refrigerant, thereby holding their mating valves 148 and 150 open. The result is to deliver compressed refrigerant vapor to condenser 16, where it condenses and then flows through restrictor 14 to the evaporator 12 from which its vapor flows to port 158. When the compressor is stopped the high and low side pressures may be allowed to equalize or not as desired. They will substantially equalize if a vapor-lock restrictor is used as shown in Fig. 4. Should the next start of the compressor be in its opposite direction of rotation the result will be to close the valves 148 and 150 and to open valves 146 and 152, thus coming back to the position shown in Fig. 4 with flow as indi' cated by the solid arrows.

As in Figs. 1 and 3 the secondary evaporator 68 of Fig. 4 is cooled only when its condenser 70 is colder than 68, with the result that refrigeration is suspended in the secondary evaporator 68 while the evaporator 12 is being defrosted. This arrangement is suitable for use in a two-temperature household refrigerator. The arrangement of Fig. 4, with the secondary system 68- 70 omitted, is also suitable for reverse-cycle air conditioning systems, as the conventional reciprocating compressor is equally eflicient in its two directions of rotation and may be operated for long periods in either direction, assuming that proper provision has been made for lubrication.

Again it will be understood that in the event that the compressor of Fig. 4 is enclosed within a sealed unit and rigidly associated with the stator of the motor, as is customary, using either internal or external spring mounting of the sealed'unit, the sudden jerk which moves the valves will be caused by resultant torque, hence the valves will operate in exactly the reverse manner. The effect however is the same because high pressure refrigerant is delivered through port 156 when the compressor is started in one direction and it is delivered through port 158 when the compressor is started in the opposite direction. In each case the former discharge tube becomes the suction tube. It is also within the scope of this invention to mount the inertia-actuated valves on the motor which drives the compressor or on the casing of a sealed unit.

ertia due to starting of the compressor.

Fig. needs no explanation, being a detail section of Fig. 4. to show that valve guides 142 and 144 are a part of'the casting 130.

Fig. 6 shows a system similar to that of Fig; 1, but employing a conventional reciprocating compressor 162 of the multiple-efiect type, i. e. one having two suction ports for two separate suction pressures. Since this is not a reversible compressor the reversal of flow is obtained by means of a valve mechanism such as shown in my c0- pending U. S. patent application Serial Number 45,343 filed August 20, 1948, now Patent No. 2,654,227. An other change from Fig. 1 is that the two pressure reducing devices are located in branch lines instead of in series. Fig. 6 also shows the use of a clock-actuated switch to causedefrosting to occur at a preselected time, preferably between midnight and daybreak;

Theswitch 164 includes blade 165 which is normally actuated by the clock 166 on such a time cycle, but may also beoperated manually when occasion requires. The lifting of this switch blade 165 breaks the circuitthrough wire 173 and the switch 174 regardless of the position of its blade 175 and energizes the circuit through wire 167 the solenoid 168 and wire 169 to lift the valves of 170 to their defrosting positions, as explained in the earlier application above mentioned. At the same time the switch closes acircuit through the

wires

172 and 172 to short out the-thermostatic switch 174 and start the compressor motor 176 if it is not already running. The clock mechanism allows the switch 164 to drop to the position shown at the'end of a short period which is established just long enough to insure that the freezer evaporator 12 is defrosted. This allows return of the valves to their normal positions as shown, due to the combined weight of the movable parts of 170 and 168 which is ample to overcome the upward liquid pressure on the valves which were closed during the defrosting operation. As an additional provision to insure the downward movement of the valves due to gravity when the solenoid 168 is de-energized I propose to employ loose fits for lost motion in the pivots which connect these valves with the armature of solenoid 168.

The

valve assemblies

34 and 66 of Fig. 1 could be used in* Fig. 6 in the same manner, but I have shown the warmer evaporator 20 fed with liquid through'the branch tube 178 and expansion valve 180, thus eliminating the valve assembly 34'. Normal flow of refrigerant is as indicated by solid arrows, the restrictor 14' being designed to'produc'e a greater pressure drop than the expansion Valli/e180 so that evaporator 12 operates at low freezing while evaporator 20 operates at a non-frosting temperature or defrosts itself during each idle period.

Closing the defrost switch 164 produces reverse cycle operation of evaporator 12- and condenser 16 without feeding either liquid or vapor to evaporator 20. Any liquid in evaporator 20' at the time defrosting starts is evaporated therein and the vapor flows through tube'60 to the auxiliary inlet of the compressor as in Fig. 1. There will'be substantially no flow of liquid through the expansion valve 180 during the short defrosting operation, though there may be some if the pressure in evaporator 20 is pulled down to below that of the condenser 16 which' oper'ates as a low pressure evaporator during the defrosting of evaporator 12. Dotted arrows indicate the now during the defrostperiod. In the event that only one evaporator is required or the secondary system 68 -70 is used, the evaporator 20-may be omitted along with expansionvalve 180 and tubes 178 and 60; This arrangement allows the use of any conventional compressor-in place of 'the multiple-suction compressor 176.

The thermostatic switch 174 may be equipped with two bulbs-so as to open when both the space cooledby'evaporator'lz and the space cooled byevaporator' 20 have been pulled] down to their required terr'ip'eratures'. For such uselI show two bulbs connected with the thermostat 174 sistance -toflow of current.

"10 and it is assumed that the thermostat is charged with a volatile fluid in such qantitythat the bulb associated with evaporator'20w'ill contain only'vapor at the cut-out point The secondary system 6870 operates as described in connection with Figs; 1, 3 and'4 and may or may not be provided with the thermostatic control valve 182.

Fig. 7 shows a modified electrical system particularly suited for use in air conditioning or when the reversecycle periods are apt to last for hours instead of minutes. The blade 183 of switch 184 is actuated in response to temperature changes of bulb 186, which is located in the space where temperature is to be controlled. A rise of temperature of bulb 186 moves the blade 183 of switch 184-downwardly, thus energizingthe'motor 176 through wires 185 to start and'185' to runwithout energizing the solenoid 168. Thus operation of the system is started normally with flow as shown by solid arrows, causing 12 to operate as the evaporator and 16 as the condenser. When the switch blade is moved in the opposite direction, either manually or in responseto a drop of temperature of the bulb 186, the motor 176 and solenoid 168 are both energized through

wires

187, 187 and 185 so that the flow of refrigerant follows the dotted arrows, causing 12 to function as a condenser and 16 as an evaporator, thus heating the controlled space. It will be seen however that the solenoid 168 remains energized only so long as the starting circuit breaker 188 remains closed with its blade 189 in the solid line position- In this case the armature of the solenoid and the movable parts of the valve assembly 170' are made'light in weight relative to valve port sizes so that the high side pressures eifective on the valves by the time the circuit breaker opens will be ample to holdth'e valves in the positions to which they have been moved by the solenoid. Thusit is only necessary to lift the valves at the start of the run and they will thereafter be held in their lifted positions by high side refrigerant' pressure until the next time the compressor is stopped. As some time will always elapse between the need for heating and the need for cooling, the pressures within the system -will'equalize to allow the valves to drop before the system is restarted.

The wiring of Fig. 7 puts the solenoid 168 in series with the startingwinding of the motor 176, which is permissible with a solenoid winding which offers little re- This arrangement is 1 preferred because'of the fact that the starting circuit breaker is thus employed to open both the starting circuit and the solenoid circuit. Thesolenoid and the starting circuit could be wired in parallel,.as they are in Fig. 6, at a slight additional cost but this-is not considered necessary.

The secondary system 68-70 ofFigs. 6 and 7 operates asin-Figs.. 1, 3, 4 and 5,. cooling evaporator 68 whenever evaporator 12is cooled. The secondary system remains idle when the evaporator 12 is functioning as a condenser.

Figure 8 is a bottom view of a preferreddesign and location of a sealed motor-compressor unit 10, such as shown in Figs. 1 to 4 inclusive. It will be understood that the lubricating system" of Fig. 2 and the gravity-actuated valves of: Fig. 3 will be modified to fit the vertical axis arrangement of Fig. 8, -as by putting the valves and

ports

18, 28 and 24-of Fig. 3 in the end plate 72 of Fig. 2. The casing of .unit 10 is flexibly mounted on the rear wall of a refrigerator and provided with parallel fins 192 instead of the usual radial fins. This is to reduce the horizontal dimension between the back of the refrigerator 194 and the wall 195 of the room. It is highly desirable to locate the motor-compressor unit in this manner and to keep one of the horizontal dimensions down to the minimumv which allows use of a suitable motor. One of the reasons for preferring a two-pole motor, running at about twice the speed of the usual four-pole motor, is to reduce its diameter for use in this location. This arrangement puts the fins in vertical planes, thus adapting the unit for'co'oling by gravity circulation of air upwardly over it.

The tube 50, which normally carries suction vapor, is preferably connected as at 60 of Fig. 2, thus the motor is normally cooled by suction vapor and high pressure vapor flows through the casing during the short defrost period only. A port not shown connects the chamber 112 (Fig. 3) with the interior of the motor casing of Fig. 8. I propose to locate the unit or a portion of the condenser near the bottom of the cabinet to provide heat for evaporating drip water to ambient air.

The electrical system of Fig. 8 may be similar to that of Fig. 6, except that the switch 164 will also reverse the motor, normally closing the motor circuit through the thermostatic switch 174 while during defrost it opens this circuit and closes the one which reverses motor rotation. In the event that defrosting is to be controlled in response to frost accumulation, door openings, a temperature change, manually or otherwise than on a time cycle the clock may be omitted.

In the event that the system of Fig. 1 is to be used in Fig. 8 the

tubes

102 and 110 will disappear and we will see tubes and 50 enter the near (bottom) end of 10 while tube 60 comes out the back of the cabinet and disappears on the far (top) end of 10, where it enters the casing, as in Fig. 2. This eliminates the valves of Fig. 3 and substitutes the valves of Fig. 1, which are preferably located inside of or adjacent to their respective refrigerated spaces within the refrigerator cabinet.

The word inertia is used in this specification and the appended claims as defined in Websters Dictionary thus: That property of matter by which it tends when at rest to remain so, and when in motion to continue in motion, and in the same straight line or direction, unless acted on by some external force.

It will be understood that a change of design from one in which the compressor body is rigidly connected with the stator of the motor, and the jerk is caused by resultant torque, to one in which the compressor body is separate from the motor stator and the starting jer is caused by frictional drag, or vice versa, will not change the fact of the valves of Fig. 3 or 4 being actuated by their inertia. It would however change the marking of switch 96 as used in either Fig. 3 or Fig. 4 and in Fig. 3 it would call for crossing the

tubes

102 and 110 to connect with 114 and 112 respectively. Instead of L (left) and R (right) the switch might be marked C (cooling) and D (defrosting) to match the detailed design.

The showing of two bulbs for switch 174 in Fig. 6 will be understood by reference to Fig. 10 of my issued U. S. Patent No. 2,349,367 or to the multiple bulbs of switch 83 in Fig. 13 of my U. S. Patent No. 2,359,780.

The modifications here shown represent only a few typical designs which utilize the principles of this invention, the main features of which are obtainable in designs having many other modifications of mechanical details.

I claim:

1. In a two-temperature refrigerating system, two evaporators of which one is cooled to a lower temperature than the other, pressure reducing means providing two stages of pressure reduction in series to feed liquid refrigerant to said one evaporator, and means for causing said one evaporator to act as a condenser while refrigerant flows through one of said stages of pressure reduction and the other of said stages is bypassed.

2. In a refrigerating system having two evaporators and a condenser, a compressor including a chamber in which compression occurs, said chamber having two ports serving simultaneously as intake ports for low pressure vapor from said evaporators and one port serving as a discharge port connected to said condenser during a first direction of compressor rotation, and means for reversing the direction of rotation of said compressor and thereby the direction of refrigerant vapor flow through said chamber, said reversal causing one of said intake ports to start serving as a discharge port for high pressure vapor flowing to one of said evaporators to heat it while the other intake port continues to take in low pressure vapor from the other evaporator and the first said discharge port starts serving as an intake port drawing vapor from said condenser which is thereby caused to operate as an evaporator.

' 3. In a refrigerating system, a pair of heat exchangers, means for operating said system whereby said heat exchangers serve as an evaporator and a condenser and alternatively as a condenser and an evaporator respectively whereby the first said evaporator is defrosted, and a secondary system comprising an evaporator and a condenser and containing a separate charge of volatile refrigerant which is partly liquid and partly vapor and is circulated solely by its density difference between liquid and vapor phases, the last said condenser being arranged in heat exchange with the first said evaporator whereby the evaporator of said secondary system is cooled only during operation of the first said evaporator as an evaporator, and due to vapor being trapped in the secondary condenser there is substantially no heating of said secondary evaporator while the first said evaporator is being defrosted.

4. In a refrigerating system employing a volatile refrigerant, a rotary compressor having a displacement chamber for circulating said refrigerant, a heat exchanger serving as a condenser, a heat exchanger serving as an evaporator, means for reversing the rotation and thereby the flow through said chamber of said compressor, and a valve enclosed within the refrigerant-containing portion of said system, said valve including means actuated in response to the reversal of pumping action due to reversal of said compressor, whereby the flow of refrigerant through said heat exchangers is modified to exchange their functions so that the first mentioned one serves as an evaporator and the second mentioned one serves as a condenser while said compressor is operated in its reversed direction of rotation.

5. In a refrigerating system, a compressor having a suction vapor inlet port a discharge port and a third port serving as a suction vapor inlet port, and means for reversing said compressor to cause said inlet port to serve as a discharge port and the first said discharge port to serve as an inlet port, said third port continuing to serve as a suction vapor inlet port.

6. In a refrigerating system, a compressor having an inlet port a discharge port and a third port serving as an auxiliary inlet port, means for reversing said compressor to cause said inlet port to serve as a discharge port and the first said discharge port to serve as an inlet port, an evaporator connected with the first said inlet port, and a second evaporator connected with said third port.

7. In a refrigerating system, a compressor for circulating a volatile refrigerant, two heat exchangers, means for reversing the flow of refrigerant to and from said heat exchangers as produced by said compressor, an expansion device in said system adapted to pass refrigerant liquid at reduced pressure when the refrigerant flows through it in either direction, a second expansion device connected in series with the first said device to provide an additional reduction of pressure during refrigerant flow in a first direction, means forming a by-pass passage around said second expansion device, and a check valve in said bypass, said check valve closing said bypass pas sage when flow is in said first direction and allowing free flow of refrigerant in the reverse direction, whereby only the first said expansion device is effective during such reversed flow.

8. In a refrigerating system of the reversible type, a heat exchanger serving at one time as an evaporator and at another time as a condenser, a refrigerant conduit connected with said heat exchanger, a chamber forming a part of said conduit, a movable member within said chamber carrying two check valves, a pair of refrigerant ports of which one is closed by one of said valves when said member is moved in one directiomand the other is closed by the other valve when themember is.-rnoved in the opposite direction, a third portopening; into said chamber in position to discharge refrigerant against said member when a first one of said ports is closedbythe associated one of said valves, and. a conduit connecting said third port with a source of refrigerant, said member being moved by a flow of refrigerant to said chamber through said third port to open one and close the other of said pair. of ports.

9. In arefrigerating system of thev reversible type, a heat exchanger serving at one time as an; evaporator and at another as a condenser, a movable member carrying a valve, a refrigerant port which. is closed by said' valve when said member is moved in one direction, means forming a chamber enclosing said member and valve, a second port opening into said chamber inposition to discharge refrigerant against said member, a conduit connected with said second port .and'witli asource of refrigerant, said memberbeing movable by a How of refrigerant through said second port from said conduit to close the first said port, a bypass for thevfirst said port, anda weighted check valve in said bypass to allow restricted flow when said first port is closed. I

10. In a refrigerating system employing a, volatile refrigerant, a rotary compressor having-two inlet. ports forlow pressure vapor and a discharge port for'high pressure vapor, two evap'orators includingone connected'with each of said inlet ports, a'cond'enser connected with said discharge port, andmeans for reversing. said compressor thereby causing said discharge port to. act as. an inlet port drawingvapor from said condenser and one of the first said inletports to become a discharge portfor vapor flowing to one of said evaporators while the other of said inlet ports continues to draw lowipressure'vapor' to saidcompressor from the other of said'evaporators.

11. In a refrigerating system, a" compressor: having two inlet ports,':anda discharge port, ailow temperature evaporator connected with one ofsaid inlet ports, a higher temperature evaporator connected with the other of said'inl'et ports, a condenser'connected with said discharge port, means whereby thezdirection of refrigerant flow is. reversed in said system. for, defrostingsaid low temperature. evaporator, and a valve arranged to stop. flow of refrigerant to said higher temperature evaporator during said defrosting of the low temperature evaporator.

12. In a refrigerating system, a compressor having two inlet ports and a discharge port, a low temperature evaporator connected with one of said inlet ports, a higher temperature evaporator connected with the other of said inlet ports, a condenser connected with said discharge port, and means for defrosting said low temperature evaporator by reversing the flow of refrigerant to deliver high pressure refrigerant vapor from said compressor to the low temperature evaporator while stopping flow to the high temperature evaporator.

13. In a refrigerating system, employing a volatile refrigerant circulated by a compressor through a condenser and an evaporator, said evaporator being adapted to operate at a frost collecting temperature, means for reversing the flow of refrigerant in said system to cause said evaporator to act temporarily as a condenser and thereby defrost while said condenser acts as an evaporator, a second evaporator connected in said system, and means effective during said reversed operation to restrict the flow of refrigerant to said second evaporator.

14. In a refrigerating system employing a volatile refrigerant, a low temperature evaporator, a higher temperature evaporator, a condenser, means for simultaneously withdrawing refrigerant vapor from said low temperature evaporator while it operates at a low evaporating temperature and from said higher temperature evaporator while it operates at a higher evaporating temperature and discharging said vapor to said condenser, means for reversing the operationof said system wherebyvapor is withdrawn from said condenser and delivered-to. said low temperature evaporator to condense therein and thereby defrost said low temperature evaporator, and means for preventing flow of refrigerant vapor to said higher temperature evaporator during-said defrosting of the low temperature evaporator.

15. In a refrigerati'ng system, two evaporators, a condenser, a compressor operating normallyas a multiple effect compressor having two inlet ports acting simultaneously to draw high and low suction vapor from said two evaporators and one discharge port through which compressedvapor normally flows to saidcondenser, r'eversibledriving means for said compressor; said compressor when reversed being arranged todraw'refrigera'nt vapor from said condenser anddischa'r'ge it through one only of the said two inlet-ports, andvalv'e means for pre venting flow of such vapor from said one inletpo'rt'to the other inlet port.

16'. In a refrigerating system employing a volatile'refrigerant, a compressor; a condenser, a high temperature evaporator, a low temperature evaporator, refri g erant flow control means providing two stages of pressure reduction for'said refrigerant, the high temperature evaporator being supplied through said first stage only and the low temperature evaporator through both stages, and. means for reversing the compressor rotation and thereby the. flow ofrefrigerant in a: portion'of said sys: tem whereby it flows through one only of said stages of pressure reduction from the low temperature evaporator to the condenser. 7

17. In a refrigerating system inluding' an evaporator normally maintained'at a temperaturebelow 32 F., a

heat exchanger normally employed as a condenser, an

evaporator normally operated at" a higher temperature than that of thefirst said evaporator, pressure reducing means for passing liquid" refrigerant to both said evap orators during their normal operation at low and higher pressures respectively, and means for reversingthe flow of refrigerant in a portion of said system'whereby'said heat exchanger serves as an evaporator; said lower rem: perature evaporator serves as a condenser while defrosting, and said higher temperature. evaporator. receives no refrigerant.

18. In a refrigerating system; a compressor, a condenser; two :evaporators, said compressor-havingia normal discharge port, a normal intake port and an auxiliary intake port, said normal discharge port being connected with said condenser, said normal intake port being connected with one of said evaporators, said auxiliary intake port being connected with the other of said evaporators,

and means for reversing said compressor to convert said normal intake port into a discharge port and convert said normal discharge port into an intake port.

19. In a refrigerating system a reversible rotary compressor having two inlet ports for low and higher suction pressures respectively and a discharge port, means for reversing the rotation of said compressor whereby said discharge port becomes a suction port, the said low suction pressure inlet port becomes a discharge port and said higher suction pressure inlet port continues to serve as an inlet port, two evaporators separately connected with the first said two inlet ports, and a condenser connected with the first discharge port.

20. In a refrigerating system charged with a volatile refrigerant, a compressor having two inlet ports and a discharge port, three heat exchangers of which each is connected with a separate one of said three ports, two

normally operate as evaporators becomes a condenser while the third heat exchanger continues to act as an evaporator.

21. In a refrigerating system employing a volatile refrigerant, a compressor of a type which reverses its direction of pumping effect when its direction of rotation is reversed, said compressor having three ports including a first port normally serving for discharge of compressed vapor, a second port normally serving for intake of low pressure vapor and a third port serving as a vapor intake port, a first heat exchanger connected with said first port and normally serving as a condenser, a second heat exchanger connected with said second port and normally serving as a low temperature evaporator, a third heat exchanger connected with said third port and serving as a medium temperature evaporator, and means for reversing the rotation of said compressor to cause said first port to serve as an intake port for low pressure refrigerant flowing from said first heat exchanger which now acts as an evaporator while said second port serves as a discharge port for compressed refrigerant vapor flowing to said second heat exchanger which now acts as a condenser and said third port continues to act as an intake port drawing vapor from said third heat exchanger.

22. In a refrigerating system employing a volatile refrigerant, means defining at least three refrigerant flow paths, a compressor including a housing forming a chamber, rotary means in said chamber for compressing refrigerant vapor and circulating it through said system, said rotary means being reversible as to direction of rotation, the reversal of rotation causing a reversal of flow through said chamber and thereby through various flow paths of said system, means forming a second chamber with References Cited in the file of this patent UNITED STATES PATENTS 87,084 Van der Weyde Feb. 16, 1869 16 Gase et a1. Mar. 15, Hilger Sept. 28, Stickney et a1. Aug. 2, Gilbert May 12, Hunt Jan. 26, Brouse Apr. 7, Beust June 23, Philipp July 21, Galson Sept. 1, Gibson Mar. 16, Vancott Nov. 9, Hilger Dec. 27, Gaede Feb. 20, Buchanan Apr. 29, Schlumbohm July 15, Allen et a1. Dec. 15, Philipp Oct. 5, Wolfert Feb. 22, McCormack Mar. 7, Kucher Mar. 21, Mufily May 27, Hagstrom Sept. 12, Mufily Oct. 10, Atchison Dec. 7, Great Jan. 11, Mackey Aug. 23, Zearfoss Sept. 20, MacDougall Nov. 1,

Jordan Jan. 3, Sporn et a1. July 4, Ewald Aug. 29, Pabst Oct. 10, Roth et a1. Oct. 10, Nussbaum Nov. 21, Feinberg Mar. 6, Wingerter Sept. 4, Morton Feb. 26, Daniels May 26, Muflly Oct. 6, Mufily Mar. 16,

FOREIGN PATENTS Great Britain Jan. 18, France Dec. 17,

UNITED STATES PATENT OFFICE CERTIFICATE ()F CORRECTION Patent No.. 2344,945 July 29, 1958 Glenn Muffly It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 52, for 'motor" read rotor column 4, line 20, strike out "that"; column 6, line 65 for "tub" read m tube column 9, line 50, for "10W" read below a Signed and sealed this 4th day of November 1958- (SEAL) Attest:

KARL H; AXLINE ROBERT c. WATSON Attesting Oflicer Commissioner of Patents