US2471448A - Built-in heat exchanger in expansion valve structure - Google Patents

Description

Patented May 31, 1949 BUILT-IN HEAT EXCHANGER IN EXPANSION VALVE STRUCTURE Edmond D. V. Platon, Paris, VII, France,

assignor to International Standard Electric Corporation, New York, `N. Y., a corporation of Delaware Application March 24, 1943, Serial No. 480,413

' In France March 18, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires March 18, 1991 c claim. (ci. ca -115) The present invention relates to high performance refrigeratlng apparatus.

Refrigerating apparatus of the type under consideration in the present disclosure employs a closed refrigerating circuit through which passes a refrigerating agent such as methyl chloride (CHaCl) or one of the so-called freon gases such as dichloro-diuoromethane (CClzFz). The refrigerating agent passes from a closed tank to an evaporator in which it is evaporatedl by expansion and from which it passes to and is compressed in a compressor and after being condensed by passing through a condenser is returned to the tank; it being possible to employ the condenser itself as the tank.

One of the objects of this invention is to improve the performance of refrigerating apparatus of this type by providing circuit regulating devices which make it possible to obtain an increase in the refrigerating effect thereof.

It is a more particular object' of this invention to provide regulators or expanders for the circuit that permit the maintenance at a constant and A determined value of the suction pressure in the evaporator circuit, an increase in the refrigerating effect per unit of refrigerant in the system, and the obtaining of a substantially maximum cooling effect from the evaporator.

In a refrigerating circuit incorporating the features of this invention, the liquid coming from the storage tank passes into a cooling circuit previously disposed around a cold expansion chamber which forms part of the pressure responsive regulator and is in communication with the evaporator. The low temperature prevailing in this cold chamber cools the liquid coming from the tank into this preliminary cooling circuit and this insures expansion of the refrigerating uid to a lower point of the refrigerating cycle, with resultant decrease in the heat content of the refrigerant just before it enters the expansion valve,

and consequent increase in its refrigerating eii'ect within the evaporator.

An expander in accordance with this invention comprises a channel or part controlled by a pressure responsive bellows that maintains constant the suction pressure of the refrigerating uid leaving the evaporator. The bellows is disposed within a chamber around which there is placed a portion ofthe circulatory circuit of the iiuid before it passes through the part and in this chamber there is provided an arrangement which increases the refrigerating eifect of the system. It also prevents the formation of frost at the joint which is located between the body of this chamber and the cap or bell of the expander owing to the fact that this joint is then at a point in the circuit where the fluid is still tepid. A thermostatic bellows that by its control imures a better performance of the evaporator may be incorporated in this expander. This bellows is provided with means for limiting its travel or movement and with a thermostatic bellows control connection. The packing that insures the tightness of the bell of the expander is arranged in such a way as to permit axial control of a rod which regulates the travel of one and/or the other of the bellows.

These as well as other features of this invention will be more fully understood from the following detailed description of a plurality of embodiments thereof as illustrated in the attached drawings.

This invention resides substantially in the combination and construction, arrangement and relative location of parts as will be described in detail below.

In the accompanying drawings, c

Figure 1 is adiagrammatic and schematic view of a. refrigerating circuit incorporating features of this invention:

Figure 2 is` a cross-sectional view showing the construction of one form of expander in accordance with this invention;

Figure v3 is a cross-sectional view of another embodiment of an automatic expander without thermostatic control in accordance with this invention.

The refrigerating circuit shown schematically in Figure 1 comprises a tank I oi refrigerating iluid in liquid state under pressure. This tank is connected by a pipe 3 to the expander, generally indicated by the reference numeral 2. The connection 3 terminates in preliminary cooling coil 4 mounted within the casing of expander 2, preferably surrounding the chamber 5 into which the fluid is discharged from the preliminary cooling coil through the port i2. The port is controlled by the valve I3, which will be referred to later.-

'I'he iiuid, after expanding through the port I2 into the chamber 5, is conducted therefrom through the pipe connection 6 into the evaporator 1. It is now in a state of low pressure and comprises a liquid vapor mixture. At the outlet of the evaporator 'l the fluid is in the form of a superheated vapor and is transmitted by a pipeline 8 to the intake valve of the compressor 9. It is delivered from the compressor in the form of a vapor of high kpressure and is passed by means of the pipe connection I0 to the condenser Il. It 1S converted in the condenser into a high pressure liquid and then passes directly into the high pressure refrigerating liquid storage tank I.

The expander 2, which includes the expansion chamber 5 and the preliminary cooling circuit 4, includes a double, pressure-responsive and thermostatic control which will now be described in greater detail. The needle valve I3 which controls the port I2 is normally held against the port so as to keep it closed by the action of spring Il which acts in the same direction on the pressure-responsive bellows I6 byl means of the rigid mechanical connection I5. The pressure-responsive bellows II is subjected on one side to the pressure in chamber 5, of which it forms a wall, in addition'to the pressure of Vspring I4, and is exposed to atmospheric pressure on its other side, since this condition prevails in the cap or bell I'I of the expander. It is also subjected to the regulated pressure of the spring I8 and of the bellows transmitted to it by the rigid mechanical connection I9. Since the atmospheric pressure which prevails in the bell I'I is assumed to be constant, if the evaporator pressure falls below a predetermined value, controllable by the spring I8, the sum of the pressures of the atmosphere and of spring I8 on the pressure-responsive bellows I6 will become greater than the sum of the pressure in chamber 5 and that of spring It. Since the balance of the pressures on its two faces is thus upset, the pressure-responsive bellows IE elongates and by means of the rigid connection I5 it removes the needle valve I3 from its seat and thus opens the port I2. The liquid which is cooled in the coll 4 then passes through the port I2, expanding into chamber 5, and passes into the evaporator 1, where it becomes vaporized. The pressure of the evaporator rises, the bellows I6 contracts gradually and the n-eedle valve I3 again closes the port I2. It can be seen that the bellows I6 thus tends to maintain the pressure in the evaporator at a constant and denite value.

The rigid connecting rod I9 makes the pressureresponsive bellows I6 integral with the thermo- 4 at the outlet of the evaporator so that the temperature of the thermostatic bulb 22 will rise, increasing the pressure within the bellows 20; the bellows will expand and, outside of the temperature margin permitted by its adjustment, will lift the needle valve I3 from its seat so that a fresh supply of liquid will pass through the port I2 into chamber 5 and to the evaporator. This v thermostatic Ibellows, consequently, tends to mainstatic bellows 20. The bellows 2U is connected by a capillary tube 2| to a thermostatic bulb 22 disposed in thermal contact or heat exchange relation with the outlet of the evaporator 1. as shown. The assembly 20-2I-22 contains a suitable expansible fluid which may be a liquid, a gas, or mixtures thereof. The different temperature conditions prevailing at the outlet of the evaporator create corresponding pressure changes in this thermostatic system. In addition, the bellows 20 is'subjected externally to the atmospheric pressure and to the action of springs I4 and 23. Its length` will, consequently, be modified by any variations in these various forces acting thereon, including changes in pressure within the bellows as a result of variations of temperature at the outlet of the evaporator. If the fluid introduced into the evaporator has not been entirely vaporized, the liquid will arrive in the suction line 8, causing it to coat with frost. The pressure-responsive bellows I6 does not act because the pressure remains constant for the entire duration of vaporization but the liquid in bulb 22 cools and the pressure drops in the bellows 20 so that it contracts under the Yaction of spring 23 and againstI the action of spring IB, and accordingly seats valve I3. Port I2 is thus closed so that no fresh supply of uid reaches 'the evaporator, whereupon the fluid that has already reached it will be able to vaporize completely. If, on the contrary, the uid is already vaporized before leaving the evaporator-1., there will be a superheated vapor tain conditions that will assure a maximum refrigerating eifect from the evaporator.

In one practical example of an embodiment of this invention an increase of 7% was obtained in the refrigerating effect.

Two examples of practical embodiments of ex panders that incorporate the features of this invention will now be described in connection with Figures 2 and 3. In these figures the reference numerals used in Figure 1 have been carried over to the corresponding elements.

The expander or pressure responsive device shown in Figure 2 is in its assembly similar to the one diagrammatically illustrated in Figure 1. It comprises a valve casing 3D ofsome suitable material, such as brass, which houses the member which contains the port or passage I2 controlled by the needle valve I3, also the pressure-responsive bellows I6 and the heat insulating bell or closure 3i of any suitable material, such as Bakelite, within which is the thermostatic bellows 20. The refrigerating fluid reaches the valve casing 30 through a threaded union 32 which screws into a pipe portion 33 forming part of the valve casing 30. The threaded union 32 is shown as having a threaded fitting 34 on its end for securing conduit 3 thereto.

The refrigerating uid ows from the pipe portion 33 through a spiral passageway 4 formed in the casing member 35 and arranged in heat exchange relation with the chamber 5 of which the pressure-responsive bellows I6 forms a wall. The member 35 which surrounds the walls forming the chamber 5 provides the helical passage Il,

which is in communication at its upper end with the conduit 33 and at its lower end through the passage 31 is in communication with the port I2. The annular member 35 in which the passage 4 is formed ts around a portion of -the casing 30 as explained and is secured thereto at the joint 36 by welding or in any other suitable manner for forming a fluid tight seal.

A filter 38 of any suitable material, such as a ne metal mesh as, for example, a perforated brass sheet, is mounted in the piping portion 33 in order to remove from the incoming refrigerating fluid any solid impurities that might be present.

The aperture I2 is formed in an annular plug 39 made of a hard metal that is not readily attacked by the refrigerating fluids employed as, for example, it may be made of a veryhard steel and the needle valve I3 of the same material. The plug 39 is threadedly mounted in a perforated supporting member 40 which in turn is threadedly mounted as shown in the casing 30. The member 40 is provided with a passage which communicates through a passage in the casing 43III with the passage 31 as shown. The perforated supporting member 4I) is mounted in the central cross-stay 4i formed as a part of the housing 30. The fluid expands through the port I2, as will be apparent, and moves up into the chamber 5 through openings in the cross-stay 4I. The refrigerating iiuid leaves the chamber 5 through a threaded female union member as shown and 'I'he needle valve I5 is rigid with a plate 45 against which the helical spring I4 rests at one end.V The other end of this spring engages a cap 44 which is threadedly mounted in a recess, as shown, in the casing 30. Secured tothe plate 43 are three rods vI'lv disposed at the apexes of any equilateral triangle. The rods4 pass through openings in the cross-stay member 4| and are l connected at their upper ends to the end plate 46 of the pressure-responsive bellows I6.

-It will be obvious that these three connecting rods insure thelateral stability of the needle valve I3. To further insure the centering of the vertical path of movement of the needle valve, it is provided with a stem, as shown, sliding in the recess I8 formed in the cap 44.

The expansible bellows I6, which has been termed herein the pressure-responsive bellows, is

be seen that the expansion or extension of the bellows will be limited by the engagement oi' the cap 60 with the enlarged end oi vthe tubular extension. On'the other hand, the bellows is i'ree to collapse without restraint from this device. Within the bellows is the spring Il which rests at its ends against the closure caps 53 and 54 respectively of the bellows.

Extending through a central passage in the member 55 is the end 62 of the capillary tube 2| of Figure 1. The end of the tube t2 is sealed to the extension comprising the half sylinders 55 and 51 and the tube in turn is sealed in the member vtill as indicated at 5l by welding or any other suitable mannen The upper end ofthe member 55 is vprovided with threads 64 which threadedly engage a collar preferably of an elastic material of some suitable metal alloy, as, for example, that sold under the trade name Tombacf4 The necks of the bellows are very deep, as shown, and this increases its flexibility. In this way the bellows faithfully and accurately follows very small changes in pressure and assumes al1 of its positions by continuous variations without intermediate balancing. ItsY opposite end is engaged by an annular ring 48, preferably of metal, secured to the adjacent portion of the casing in any suitable manner to form a seal and to the adjacent end of the bellows I5.

'I'he upper end of the bellows I5 is closed or sealed from the space defined by the bell 3| by a member 49 preferably of Bakelite or other suitable material of poor heat conducting ability. The member 49 is preferably mounted in the bell by means of screw threads as shown. The member 49 has a passage, as shown, at its center through which the rod I9 extends which in turn is riveted, as shown, to the centery of the closure plate 46 for the bellows. The rod I9 has an integral collar 50 against which one end of the spring 23 rests with its other end against the perforated end of the member 49. The member 49 when mounted in the bell 3| locks in place a plate or wall member 5| to define the lower wall of the chamber formed by the bell 3|. The member 5| may likewise be made of hcat insulating material so as to isolate the compartments and elements contained therein from heat exchange. The

. upper end of the rod I9 rests against a member 52 mounted in one end of the bellows 20 which in turn is housed in the bell 3| above the `wall 5|. The member 52 is mounted in the end or closure plate 53 sealed to the flexible wall of the bellows 20 as shown.

A device for limiting the movement of the bellows 20 is employed but it should first be noted that the other end of this bellows is sealed to a plate 54 which is secured at its center to a rod 55 forming part of the adjusting mechanism for the bellows. Mounted on the lower end of the member 55 and lying within the space defined by the bellows 20 is a tubular member comprising the half cylinders 56 and 51 which terminate at one end in the cam shaped head portions 58 and 59. Threadedly attached to theupper end of the abutment member 52, which is hollow, is a cap 60 which is perforated at the center by a passage the walls of which converge downwardly. \Thus the cam shaped heads 58 and 59 may be passed through this passage when the half cylinders are compressed together and then separated to locky mounted in the adjusting cap 55. Only axial movement of the member 55 is l'ermitted by reason ofl the` pin' 61 mounted therein and projecting into a longitudinal groove 58 in the bell 3|. Surrounding the member 55 is a packing y means comprising the packing 59 and the adjustable sleeve 10 threadedly mounted in the upper end of the bell 3|.

Thus it will be seen that the mechanism for closing the upper end of the bell 3| includes means for axially adjusting the member 55 and, consequently, the position of the end of the bellows 20 closed by the plate 54. The packing means forms a tight seal around the member 55 without interfering with its axial adjustment by rotating cap 86. This results from the fact that the cap 66 is provided wi h a screw 1| vmounted in the metallic insert 12 the cap 68 which, it may be noted is preferably of a suitable heat insulating material. This is the reason for forming the threads which engage the threads on the member 55 in a metal insert 65 molded into the cap 55. 'Ihe end of the screw II engages in an annular groove 'I3 in the bell 3|, as shown, so that the only movement which can result from the rotation of the cap 66 is the desired axiai movement of member 55. This provides a simple arrangement for effecting the adjustment of means for undue chilling by the refrigerating fluid in the chamber 5. Since the packing elements 59-15 separate the chamber I1 in bell 3| from the atmosphere, the operation of the entire nit will be stable in so far as variations in atmospheric pressure are concerned and independent of ambient temperature conditions.

The arrangement of Figure 3 employsdn a large part the construction of the expander of Figure 2 below the wall 5|. In this embodiment of casing or bell 3|, the preliminary cooling circuit 4 and the pressure-responsive bellows |9 are of the same design as previously described and the details thereof are consequently indicated by the same reference numerals and further description.

pressure-responsive control of the expander and, therefore, rod i9 ls modified as shown.I The collar 50 is disposed nearer the lower end of the rod i9 and the compression spring 23 is interposed between its upper face and the end of the member 55. The member 55 is provided With a counterbore 16 in which the upper end of the rod I9 may slide as the bellows i6 expands and contracts when subjected to pressure variations. The adjustment by cap 66 as before causes axial positioning of the member 55 and, therefore, varies the extent of compression of spring 23.

From the previous description of Figure 1, it

.will be understood how the expanders of Figures 2 and 3 operate and, therefore, no further detailed description of their operation seems necessary. As represented by two examples herein disclosed, it becomes apparent that those skilled in the art will readily appreciate that many variations and adaptations of the subject matter of this invention can be developed without departing from the novel subject matter thereof. I do not, therefore, desire to be strictly limited to the disclosure as herein given but rather to the scope of the claims granted me.

What is claimed is:

1. A method of refrigerating with a vaporizable refrigerating liquid in a refrigerating system having an evaporator, which comprises comi pressing the refrigerant to form a high pressure liquid, precooling the high pressure liquid in a first zone by conducting it therethrough in heat exchange relationship with low pressure liquid refrigerant in a second zone, expanding the high pressure liquid from said first zone into said second zone, after it has been precooled, to form low pressure fluid, conducting such low pressure fluid to the evaporator, and preventing the expansion of the high pressure liquid refrigerant whenever liquid refrigerant is leaving the evaporator.

2. A method of refrigerating with a vaporizable refrigerating liquid in a refrigerating system having an evaporator and an expansion valve, which comprises compressing the refrigerant to lform a high pressure liquid, precooling the high pressure liquid by conducting it in heat exchange relationship with low pressure liquid refrigerant within said expansion valve, expanding the high pressure liquid through said expansion valve, after it has been precooled, to form low pressure fluid, conducting such low pressure fluid to the evaporator, opening the expansion valve in respon:o to reduced pressure in the evaporator, and preventing the opening of the expansion valve, whenever liquid refrigerant is leaving the evaporator.

3. In a refrigerating system comprising a va porizable liquid refrigerant, a compressor, an evaporator, and an expansion valve including a throttling port, means within said valve for precooling high pressure liquid refrigerant by conducting it in heat exchange relationship with low pressure liquid refrigerant` before it passes through said port, and means responsive to the escape of liquid refrigerant from the evaporator for preventing the opening of said expansion valve.

4. In a refrigerating system comprising a vaporizable liquid refrigerant, a compressor, an evaporator and an expansion valve including a throttling port, means Within said valve for precooling high pressure liquid refrigerant by conducting it in heat exchange relationship with low pressure liquid refrigerant before it passes through said port, means responsive to reduced pressure in said evaporator for opening said expansion valve, and means responsive to the escape of liquid refrigerant from the evaporator for preventing the opening of said expansion valve.

5. A device for use in refrigerating systems comprising an expansion Valve including a casing and a throttling port therein, an inlet chamber within said casing through which refrigerant must pass before reaching said port, an outlet chamber within the casing through which refrigerant must pass after passing through said port, said inlet chamber surrounding and being in heat exchange relationship with said outlet chamber.

6. In a refrigerating system of the compressorcondenser-expander type employing an evapora-- tor, the method of regulating the refrigeration cycle to give a maximum refrigerating effect in the evaporator which includes the steps of precooling high pressure liquid in a first zone by conducting it in heat exchange relationship with the liquid component of low pressure refrigerant in a second zone, and expanding the high pressure liquid from said first zone into said second zone after it has been precooled and before it is supplied to the. evaporator.

. EDMOND D. V. PLATON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS starr Nov. 12,1940

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