US2694296A

US2694296A - Flow restricting device

Info

Publication number: US2694296A
Application number: US251400A
Authority: US
Inventors: John R Prosek; Joseph A Galazzi
Original assignee: International Harverster Corp
Current assignee: Navistar Inc
Priority date: 1951-10-15
Filing date: 1951-10-15
Publication date: 1954-11-16
Anticipated expiration: 1971-11-16

Description

Nov. 16, 1954 J. R. PROSEK ETAL 2,694,296

FLOW RESTRICTING DEVICE Filed Oct. 15, 1951 2 Sheets-Sheet l FIFE/6517A 7' 101V 52 29 ,30 37 REFR/EERATION ro VAPORA roR 7'0 M4PORATOR 7'0 CAPILLARY 17 2 enzons:

4/5677, If 1 70821? a/s e vfi 'alazzz' United States Patent FLOW RESTRICTIN G DEVICE John R. Prosek and Joseph A. Galazzi, Evansville, Ind.,

assignors to international Harvester Company, a corporation of New Jersey Application October 15, 1951, Serial No. 251,400 6 Claims. (Cl. 62-115) This invention relates to flow restricting devices generally, but more particularly to a refrigerant flow restricting mechanism adapted for use in a refrigeration system wherein defrosting of the cooling unit is accomplished by reversing direction of flow of refrigerant through portions of the refrigerating apparatus.

ln the modern household refrigerator using the compressor-condenser-evaporator-type refrigerating system, periodic defrosting of the evaporator cooling element, for the purpose of removing accumulations of frost-like condensate thereon, may be accomplished by any one of several different methods. One method, however, that has found some favor in the industry involves reversing the direction of flow of refrigerant through a portion of the apparatus whereby the hot compressed refrigerant gases from the compressor are directed into the evaporator cooling unit instead of into the condenser.

1n arrangements of this character the heat of the compressed refrigerant is employed to raise the temperature of the evaporator surfaces sufliciently to effect a melting of any ice or frost accumulated thereon, and when the elevation of this temperature is accomplished with considerable rapidity there is no appreciable change in the temperature of the food products stored in the refrigerator. If, however, the temperature of the compressed refrigerant is not suflicient to rapidly effect a melting of the accumulated frost, and such reverse flow operation has to be continued to for an appreciable length of time, there is a danger that the temperatures in the food storage compartments will likewise be raised sufliciently to cause damage to any food stored therewithin.

In the past, defrosting systems of this character have not been entirely satisfactory primarily because the length of time required to effect defrosting of the evaporator was so great that a noticeable rise in temperature in the food storage compartments usually accompanied such reverse flow operation with the consequent prospect of food damage unless closely supervised. The basic reason for such slow and unsatisfactory operation was found to be primarily the result of attempting to operate the refrigeration system on the reverse cycle with the same degree of refrigerant flow restriction as that employed on the refrigeration cycle. It was found, however, that on the reverse or defrost cycle, the desirable pressure drop from the evaporator unit through the restricting device to the condenser unit is somewhat less than that ordinarily required for satisfactory operation on the refrigeration cycle; hence when the same degree of restriction is employed on both cycles unsatisfactory operation can be expected on at least one of the cycles. Since the refrigeration system is most frequently balanced for ideal operation on the refrigeration cycle, and since no suitable means has heretofore been developed to compensate for or to accommodate such desired variation in fiow restriction, it will readily be understood why the operation of such a system on the reverse or defrost cycle will not be entirely satisfactory.

In the conventional refrigeration system, an expansion valve or a capillary tube is generally used to reduce pressure and to meter the flow of refrigerant between the condenser and evaporator; but when the direction of flow of refrigerant therein is frequently or periodically reversed, as for defrosting purposes, the fixed and inflexible characteristics of these devices limit their adaptability and usefulness. The expansion valve, for instance, is essentially a uni-directional flow device, while the capillary tube restrictor, with its substantially identical flow restricting characteristics in both directions, cannot be balanced for effective reverse flow operation and, at the same time, provide satisfactory operation during the refrigeration cycle. When properly balanced for normal operation the capillary tube otters so much restriction to flow that in the reverse direction the refrigerant entering the evaporator remains largely in the evaporator. As a consequence, the passage or refrigerant is so slow that heating of the food storage compartments frequently occurs before defrosting is accomplished. Neither of these well known prior art restricting devices, therefore, has ever been entirely satisfactory for operation in a refrigeration system wherein refrigerant flow is occasionally reversed, as for defrosting purposes, and flow restricting characteristics differing from those of the refrigeration cycle must be provided. Furthermore, no other simple highly effective means capable of satisfactorily performing under such varying flow conditions has heretofore been proposed, hence it is readily understandable why defrosting systems using the reverse refrigerant flow principle have not been more universally accepted. The present invention, however, does provide the desired variation in flow restriction when direction of refrigerant flow through the circuit is reversed, hence it effectively overcomes the difficulties heretofore encounteredin a refrigerating system when such system employed a reverse cycle operation for defrosting purposes.

It is a principal object of this invention, therefore, to provide in a refrigerating system refrigerant flow restricting means which offers a predetermined restriction to the flow of refrigerant therethrough in one direction and a different restriction to flow therethrough in the opposite direction.

Another object is to provide an auxiliary flow restrictor for use in a refrigerating system which is adaptable for increasing the restriction to refrigerant flow in one direction through the system.

A further object is to provide an improved refrigerating system wherein the evaporator cooling element is defrosted by reversing the direction of flow of refrigerant therethrough.

A still further object is to provide a refrigerating system having a reversing valve therein whereby the direction of flow of refrigerant through portions of the circuit may be reversed for the purpose of defrosting the evaporator cooling element of the system.

A yet still further object is to provide an auxiliary flow restrictor device adaptable for use with a capillary tube restrictor in a refrigerating system for increasing the restriction to refrigerant flowing in one direction only through the syste Another important object is to provide a simple, rugged, non-adjustable and inexpensive flow restrictor device having no movable parts and arranged to offer a greater resistance to flow of refrigerant therethrough in one direction than in the opposite direction, and which is adaptable for use in a refrigerating system that may be operated on reverse cycle for defrosting purposes.

A further important object is to provide a refrigerant flow restricting device having a chamber and choke means therewithin for increasing turbulence and the resistance to flow when refrigerant flows therethrough in one direction.

The foregoing and other objects and features of the invention will become apparent as the disclosure is more fully made in the following detailed description of a preferred embodiment of the invention as illustrated in the accompanying sheets of drawings, in which:

Fig. 1 is a schematic diagram of a refrigerating system embodying the restrictor device of the present invention, the refrigerating apparatus being shown in operating position for producing refrigeration of the evaporator.

Fig. 2 is an enlarged sectional view of a preferred form of the auxiliary restrictor device of the present invention as employed in the refrigerating system during the refrigeration cycle.

Fig. 3 is a View similar to Fig. 1 but with the refrigerating apparatus shown in operating position for producing defrosting of the evaporator.

Fig. 4 is similar to Fig. 2 but shows the auxiliary restrictor device as it is employed in the refrigeration system during defrosting of the evaporator.

Figs. and 6 are enlarged sectional views showing modified forms or constructions of the proposed auxiliary restrictor device.

By reference to the drawings it will be noted the refrigerating system selected for schematic illustration is of the conventional compressor-condenser-evaporatortype wherein the direction of flow of refrigerant through the evaporator cooling-unit may be reversed, as indicated by the directional arrows in Figs; 1 and 3, in order to effect the defrosting thereof. In Fig. l, for instance, the direction of flow of refrigerant through the system, as indicated by the arrows, is shown as normal or that which will produce refrigeration of the cooling unit, while in Fig, 3 the direction of refrigerant flow through portions of the system is shown, as indicated by the arrows, as reversed with respect to that of Fig. 1, and the system as so operated will produce defrosting of the cooling unit.

In a refrigerating system of this character, the discharge outlet of a conventional motor-compressor unit 10 is connectedby a conduit 11 to an opening 12 in a reversing valve device 13, an opposite outlet 14 of which connects by a conduit 15 to the inlet of a condenser 16 while the outlet of said condenser may, if desired, be connected by a conduit 17 to a drier unit 18, the opposite side of which connects by a conduit 19 to the inlet of a capillary restrictor tube 20. The outlet of said capillary, in accordance with the teachings of the present invention, may connect by conduit 21 to one side of an auxiliary restrictor device, indicated generally by the numeral 22, while the opposite side or outlet thereof is connected by conduit 23 to the inlet of an evaporator cooling unit 24. The outlet of said evaporator connects by a conduit 25' to an opening 26, of the reversing valve 13, and a corresponding opposite outlet passage 27 of said valve connects by conduit 28 to the suction inlet of said motor-compressor unit. It will be understood, of course, that refrigerant will be circulated within the apparatus for purposes of effecting refrigeration.

The individual components or units of the system, with the exception of the auxiliary restrictor 22, are generally conventional, and, since their specific use and application in a refrigerating system are well understood in the art, it is believed further description of the structural details thereof, and of the conventional control devices generally associated therewith, is unnecessary.

The reversing valve 13 is, preferably, of the conventional 4-way type, such for instance as is described and illustrated-in the Walfert Patent 2,342,566, dated February 22, 1944, having dual inlets and outlets and canals or passageways therewithin arranged so that refrigerant incoming from the compressor may be directed, either, to the opening 14 leading to the condenser or to the opening 26 that is connected by a conduit with the evaporator. It should be understood, of course, that when refrigerant incoming from the compressor through opening 12 is directed, by way of opening 26, to the evaporator, instead of through opening 14 to the condenser, the discharge from the condenser will be directed from the valve opening 14 across to the opening 27 that connects said valve, by way of conduit 28, to the suction side of the compressor, thereby effecting a reversal of refrigerant flow through portions of the system. Since valves of this character are generally old and well known in the art as heretofore indicated, and since the specific valve mechanism employed is not pertinent to the operation of the instant invention, the details thereof have not been shown with any great degree of particularity. Likewise, means for operating said valve have been omitted because it is immaterial whether manual, senili-automatic or automatic operation is employed therewit In one preferred embodiment, as illustrated in the sectional views of Fig. 2 and 4, the proposed auxiliary restrictor device 22 is depicted as fashioned with a tubular outer member 29 having the opposite ends thereof swaged or otherwise drawn to provide reduced section portions indicated, respectively, at 30 and 31. Intermediate the reduced ends of said outer tubular member, there is provided a fluid choke device fashioned, preferably, as a longitudinally extending core-like circular plug member 32 shaped to conform with the interior surface of said tubular member. The opposite ends of said plug are trimmed so as to present substantially flat

end wall surfaces

33 and 34, respectively, that are normally disposed with respect to the longitudinal axis thereof, while a cone-shaped or tapered passageway 35 extending through the center of the plug connects a small opening 36, in the end wall 34, with an enlarged opening 37 in the opposite end wall 33. The end walls, 33 and 34, are inwardly spaced from the respective reduced end portions of said outer tubular member so as to provide expansion or

turbulence chambers

38 and 39. If desired, said plug member may be fashioned as an integral portion of the tubular outer member but, preferably, it is separately fabricated and then positioned in'said tubular member in a press-fit relationship so that once positioned therewithin it will remain fixedly disposed indefinitely. If desired, of course, the tubular member may be long enough to position two or more such plug-like members at spaced intervals therewithin for the purpose of increasing resistance to refrigerant flow therethrough.

In operation, the proposed auxiliary restrictor functions to restrict the flow of refrigerant between the capillary tube and the evaporatorinlet and thus aids or supplements the restricting action of said capillary when the refrigerating system operates on the refrigeration cycle. When the refrigerant from the capillary first enters said auxiliary restrictor, it passes into the chamber 39 where it may expand and bombard or impinge against the barrier provided by the end wall 34 of the plug member 32. As a result of such action, a turbulence is set up within said chamber which operates to increase the entrance loss and thus permits only a small or limited portion of the refrigerant to pass, by way of the small opening 36, passageway 35, and the enlarged opening 37, into the chamber 38 at the opposite end of said restrictor. The turbulence thus set up will continue, so long as refrigerant flows thereinto, to retard or restrict the movement of said refrigerant through said restrictor, thereby aiding or supplementing the capillary tube in restricting refrigerant flow between the condenser and evaporator units. On the other hand, when the system is operating on the defrost cycle the direction of refrigerant flow is from the evaporator 24, through the auxiliary restrictor 22, to the capillary tube 20, in which case refrigerant enters the restrictor through conduit 23 and flows immediately into the expansion or turbulence chamber 38. Since the end wall barrier 33 provides very limited restriction, and since the opening 37 is enlarged, there is very limited opportunity for setting up any appreciable turbulence to restrict flow therethrough; hence refrigerant flows easily into and along the gradually tapering passageway 35 and discharges through the opening 36 into chamber 39 from where it passes by way of conduit 21 into the capillary tube. It will readily be appreciated that the flow of refrigerant through the auxiliary restrictor in this direction is substantially free flowing and uninhibited; consequently, substantially no turbulence is produced therewithin and restriction to flow of refrigerant therethrough is minimized. Under these conditions the auxiliary restrictor does not appreciably add to or supplement the capillary tube in providing a restriction to refrigerant flow between different portions of the refrigerating system.

In Figs. 5 and 6, two modifications of the proposed restrictor device depict structures that differ slightly in construction from the preferred embodiment heretofore described, but which function in substantially identical fashion to produce the same desirable result. Direction arrows on these views indicate the direction of refrigerant flow therethrough during the respective refrigeration and defrosting cycles. In Fig. 5 the restrictor shown includes a tubular outer member 40 having reduced end portions 41 and 42, and a choke-like plug member 43 positioned therewithin between the

chambers

44 and 45. The plug 43 is shaped, preferably, to conform substantially with the interior surface of said outer member and is positioned therewithin in a press-fit relationship. Opposite ends of said plug are fashioned to present

surfaces

46 and 47 normally disposed with respect to the longitudinal axis thereof. A bore or passageway 48 that diminishes in cross-sectional dimension throughout its length extends from end to end through the center of the plug. A passageway such as indicated may be fashioned from a series of successively graduated, axially aligned

adjacent bores

49, 50 and 51 that are arranged to cooperate and form steps or setback ledges 52 and 53 disposed at spaced intervals along the walls of said bores.

The restrictor depicted in rig. 6 includes a tubular outer member 54 having reduced

end portions

55 and 56, and a choke plug member 57 positioned therewithin between the chambers 58 and 59. The plug 57 is shaped, preferably, to conform substantially with the interior surface of said outer member and is positioned therewithin in a press-fit relationship. One end of said plug is fashioned to present a flat end surface 60 that is normal to the longitudinal axis thereof, while the opposite end is fashioned with a longitudinal offset 61 that joins axially spaced flat end surfaces 62 and 63 likewise normally disposed with respect to said longitudinal axis, and a tapered or cone-shaped bore or passageway 64 that extends from end-to-end therethrough.

In operation, the restrictors of Figs. 5 and 6 function in much the same fashion as previously described in connection with the embodiment illustrated in Figs. 14. During the refrigeration cycle, in the restrictor depicted in Fig. 5, refrigerant flows from the capillary by way of conduit 21, into the chamber 45 where it bombards and impinges first against the barrier wall 47 and then, successively, against the

ledges

52 and 53 within the passageway 48. Since entrance losses are known to rapidly multiply, as a result of sharp bends or rapid changes in direction of the flow of a fluid, it will be appreciated that the

ledges

52 and 53 operate to supplement the action of the wall barrier 47 in setting up a restricting turbulence that tends to restrict the flow of refrigerant from the capillary 20, through the tapered passageway 48 and chamber 44, into the evaporator 24. On the defrost cycle however, the flow through the restrictor being in the reverse direction, the refrigerant will flow more freely because only the one wall barrier 46 is disposed in the path thereof to create or set up a turbulence. As a consequence, substantially less turbulence will be created and no appreciable or seriously objectionable restriction to flow through the restrictor in this direction will be encountered. Likwise, in Fig. 6, during the refrigeration cycle, the offset surfaces 62 and 63, of the end wall barrier, operate to restrict flow and produce turbulence when refrigerant impinges thereagainst, but during the defrost cycle, when refrigerant flows through the restrictor in the reverse direction, no appreciable resistance or restriction is encountered, thus the restriction to flow therethrough is minimized.

From the foregoing, it will be readily apparent that the proposed refrigerant flow restrictor represents a new,

novel and highly etfective device that will greatly im prove the operation of a refrigeration system employing the reverse flow principle for defrosting the cooling unit thereof. Furthermore, the proposed device is simple, inexpensive, and contains no movable parts or elements that might readily wear, deteriorate or get out of adjustment as a result of normal use. In addition, the proposed restrictor is readily adaptable to any conventional refrigeration system and requires only a minimum of modification or alteration to permit its installation in the refrigeration circuit.

Although only a preferred form of the invention, and

several structural modifications thereof, has been illustrated and described in detail, it will be apparent to those skilled in the art that various other modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What is claimed is:

1. A flow-restricting device for restricting flow of refrigerant through a refrigerating system comprising: a longitudinal member having a central bore therethrough and adapted to have one end thereof connected to one portion and the other end connected to another portion of a refrigerating system, fluid-restricting means within said member, said means including a choke member disposed in spaced relation to the ends of said longitudinal member and arranged so as to provide a chamber between each end of said choke member and the respective proximate end of said longitudinal member, said choke member having one end thereof substantially flat and normally disposed with respect to the longitudinal axes thereof while the opposite end of said member is fashioned with an axially extending oifset that forms said end portion into two axially spaced end face surfaces normally disposed with respect to the longitudinal axes, and having said choke member further provided with a gradually tapering bore extending longitudinally therethrough and communicating with the chambers at opposite ends thereof.

2-. In refrigerating apparatus, the combination of a compressor, a condenser, an evaporator, a flow-restricting tube, a flow-reversing valve, tubing connecting said condenser, flow-restricting tube, and evaporator in series, additional tubing connecting said flow-reversing valve with the compressor, condenser, and evaporator, in operating relationship whereby said reversing valve functions to direct the flow of refrigerant from the compressor selectively either through the condenser and thereafter through the flowrestrieting tube and the evaporator in one direction or through the evaporator in the opposite direction and thereafter through the flow-restricting tube and the condenser, additional flow-restricting means characterizedby having greater restriction to flow when refrigerant flows therethrough from the condenser to the evaporator than when refrigerant flows therethrough from the evaporator to the condenser, and tubing connecting the said resatricting means in series with the said flow-restricting tu e.

3. In refrigerating apparatus, the combination of a compressor, a flow-reversing valve, a condenser, a flowrestricting tube, an evaporator, tubing connecting said condenser, flow-restricting tube, and evaporator in series, additional tubing connecting said flow-reversing valve with said compressor, condenser, and evaporator in operating relationship whereby said reversing valve functions to direct the flow of refrigerant from the compressor selectively either through the condenser and thereafter through the flow-restricting tube and the evaporator in one direction or through the evaporator in the opposite direction and thereafter through the flow-restricting tube and the condenser, a flow-restricting device, and tubing connecting the said flow-restricting device in series in the tubing that connects the said flowrestricting tube with said evaporator, said flow-restricting device being additional to the flow-restricting tube and constituting together with said flowrestricting tube a flow-restricting means characterized by having a high restriction to the flow of refrigerant when the direction of flow is from the condenser through the flow-restricting tube and flow-restricting device to the evaporator and a low restriction to the flow of refrigerant when the direction of flow is from the evaporator through the flow-restricting' device and flow-restricting tube to the condenser.

4. In refrigerating apparatus, the combination of a compressor, a condenser, an evaporator, a capillary tube fiow restrictor wherein the restriction to flow is the same in either direction for a refrigerant flowing therethrough under identical conditions of temperature and pressure in both directions, a flow-reversing valve, tubing connecting said condenser, capillary tube flow restrictor, and evaporator in series, additional tubing connecting said flow-reversing valve with said compressor, condenser, and evaporator, in operating relationship whereby said reversing valve functions to direct the flow of refrigerant from the compressor selectively either through the condenser and thereafter through the capillary tube flow restrictor to the evaporator in one direction or through the evaporator in the opposite direction and thereafter through the capillary tube flow restrictor to the condenser, additional floW-restricting means connected in series between the condenser and evaporator, said additional flow-restricting means including a flow-restricting device characterized by a relatively large pressure drop when the fiow of refrigerant therethrough is from the condenser through the capillary tube flow restrictor and said additional flow-restricting device to the evaporator and a relatively small pressure drop when the flow of refrigerant is in the reverse direction.

5. In refrigerating apparatus, the combination of a compressor, a condenser, an evaporator, flow-restricting means in which the restriction to the flow of a refrigerant therethrough is a function of direction of flow whereby the restriction to flow through said means in one direction and at any given temperature and pressure is greater than the restriction to flow therethrough in the opposite direction at the same temperature and pressure, a flow-reversing valve, tubing connecting said condenser, flow-restricting means, and evaporator in series, additional tubing connecting said flow-reversing valve with said compressor, condenser, and evaporator, in

operating. relationship whereby said reversing valve functions to direct the flow of refrigerant from the compressor selectively either through the condenser and thereafter through the. flow-restricting means and the evaporator in one direction or through the evaporator in the opposite direction and thereafter through the flowrestricting means and the condenser.

6. The combination recited in claim 5, and further characterized by havingrsaid flow-restricting means include a length of small diametered capillary tubing connected to a tubular member having a choke therein, and having the choke positioned so that the flow-restricting means offers the greatest restriction to the flow of a refrigerant therethrough when the direction of flow is from the capillary tube portion thereof to and through the choke portion to the evaporator.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,704,177 Davenport Mar. 5, 1929 2,456,626 Dahnke Dec. 21, 1948 2,589,384 Hopkins Mar. 18, 1952