US2231163A - Expansion valve - Google Patents

Description

Feb. 11, 1941. J N 2,231,163

EXPANSION VALVE Filed March 21, 1938 INVENTOR. Pay 14 JOHN-501V.

ATTORNEY.

mumh b Patented Feb. 11, 1941 2,23LI63 STATES PATENT OFFEC EXPANSION VALVE Roy W. Johnson, Milwaukee, Wis.

Application March 21, 1938, Serial No. 197,105

Claims. (01. 23692) This invention relates to an improvement in this makes it practical to provide a pressure thermostatic expansion valves combined with a chamber on the power side of the diaphragm of vapor compression refrigerator machine. small volume. As usual .this pressure chamber One of the objects of the present invention is connects through a capillary tube with a bulb 5 to provide a valve of this character which is so clamped to the suction line or some suitable part 5 compactly and closely organized as to require a of the evaporator. The small volume of the presminimum number of parts and hence be small sure chamber of the power element makes it in size and yet of rugged construction and highly practical to employ a bulb of small size and yet efficient and reliable, though flexible, in operahaving a volume greater than the combined voltion. ume of the pressure chamber and the capillary 10 Another object of the invention is to provide tube. For example, if the combined volume of a thermostatic expansion valve which is superthe pressure chamber and capillary tube is 8 sensitive in that a diaphragm of comparatively cubic centimeters then a bulb is employed which large area operates directly on a small needle has a volume of 8.3 cubic centimeters. With this valve so mounted and controlled as to eliminate relationship between the pressure chamber, capil- 15 practically all friction. The valve is of the carlary tube, and bulb of the power element, the tridge type and is so constructed and organized a power element may be so charged with refrigas to be self-alining and exercise a very close erant that the refrigerant will always have the regulating function and yet is readily removable surface from which vaporization occurs disposed to provide, if ever necessary, for replacement or within the confines of the bulb. This has the 20 change of orifice size. Because of its superimportant advantage of insuring that the bulb sensitive character the valve holds super-heat has control at all times and under all conditions. within very narrow limits. Provision is made The bulb will retain control even though the exhowever, for an adjustable super-heat range. pansion valve is encased in ice. Hence the valve For example, the particular valve structure disbody can be placed in an ambient temperature closed herein has an adjustable super-heat range higher or lower than the bulb temperature. between 0 and 35 degrees Fahrenheit. The invention provides a thermostatic expan- In order to have the desirable small size and sion valve which maintains a constant super-heat simplicity of structure and also obtain eflicient over a wide range of evaporator temperatures and operating characteristics, a charging refrigerant which permits operation at low super-heat at 30 such as methyl chloride is employed in the power normal operating pressures without flooding back element having a vapor pressure curve lying on high evaporator temperatures. There is not below that of the system refrigerant such as only assurance against flooding back of the liqfreon and a loading spring is combined with the uid at the starting cycle but the power needed diaphragm of the power element in such manner in the compressor motor, when the evaporator 35 as to make itpossible to obtain an equilibrium. temperature is high, is limited.

The loading spring and the adjustable spring for Other objects and advantages reside in cerincreasing or decreasing thesuper-heat are contain novel features of the construction, arrangecentrically disposed in the outlet chamber of the ment and combination of parts which will be valve as a further measure to render the struchereinafter more fully described and particularly 4G ture small and compact. pointed. out in the appended claims, reference The outlet chamber into which the refrigerant being had. to the accompanying drawing formdirectly flows from the orifice has one of its ing a part of, this specification, and in which: walls constituted by the diaphragm of the power Figure 1 is a view partly in central vertical sec- 5 element. The organizationis such that when tion and partly in side elevation showing a therthe valve opens, the refrigerant in the outlet mostatic expansion valve embodying the present chambers exerts a cooling effect through the invention together with its capillary tube and diaphragm on the charging refrigerant of the bulb; power element located on the opposite side of Figure 2 is a view in perspective of the parts the diaphragm resulting in an instantaneous showninFigure 1; and 50 closing movement of the valve. Hence the valve Figure 3 is a diagrammatic view in'elevation ilis self-modulating or dampening in action. lustrating the application of the expansion valve,

While the area of the diaphragm is large in .its capillary tube and bulb to a refrigerating sysrelation to the metering valve proper, the valve tem. 65 as a whole, diaphragm included, is small, and Referring to the drawing, the expansion valve is designated generally by the reference character V, the capillary tube at C, and its cooperating bulbat B. As usual, the expansion valve V is incorporated in the liquid refrigerant supply line L leading to the cooling or evaporator coil E and the bulb B is clamped to the suction line S leading from the evaporator coil E to the motor driven compressor M.

The expansion valve V comprises a valve body 5 provided with an inlet 6 equipped with a strainer I and also provided with an outlet 8. A passageway 9 leads from the inlet 6 into the opening or port of a ported partition designated at Ill. The partition I has an integral upwardly extending sleeve I provided at its upper end with an inturned flange l2. A unitary valve assembly or cartridge type valve designated generally at I3 is inserted in the sleeve II and regulates and meters the flow of liquid refrigerant through the ported partition and into an outlet chamber l4 in open communication with the outlet ll.

One of the walls of the outlet chamber is con-" stituted by the diaphragm l5 of the valve V, the periphery of the diaphragm being clamped between an outwardly extending annular flange l6 integral with the upper end of the valve body and the periphery of a head I'I-whichjs mechanically interlocked with and sealed to the flange IS. The head and .the diaphragm |5 define between them the pressure chamber N3 of the power element of the valve, which power element is constituted of this pressure chamber and its diaphragm, the capillary tube C and bulb B. I

The cartridge type valve |3 comprises a valve cage which is threadedly interconnected with the sleeve H, a valve seat 2| threadedly interconnected with the cage 20, a needle valve 22 which is floated in the cage 20 and co-acts with the seat 2|, and a spring 23 which is interposed between the lower end of the needle valve and the bottom of the cage and which biases the needle valve to closed position, that is, into engagement with its seat. The lower portion of the cage 20 is of reduced external diameter and has passages 24 extending therethrough to afford communication between that portion of the interior of the ported partition which communicates with the passage 9 and theinterior of the cage and of the valve seat. The valve 22, except for its lower end portion, is smaller than. the opening through the cage and valve seat so that the liquid refrigerant can flow around the valve to the port or orifice in the valve seat. The lower end of the valve 22 has guiding engagement with the lower portion of the wall of the cage, as indicated at 25.

This unitary valve assembly may be inserted in the sleeve and removed therefrom through the port of the partition and through an opening in the bottom of the valve body.

In the assembly, the valve cage 20 is turned up in the sleeve until the shouldered upper end of the valve seat 2| firmly abuts the inturned flange l2. of the sleeve After the valve assembly has been inserted, the inlet side of the valve is sealed off by means of a flanged cap nut 26 threaded into the lower end of the port of the partition and having hermetic sealing engagement therewith.

The diaphragm I5 directly operates the valve 22 and for this purpose it is provided at its center with a buffer plate arrangement 21 securely interconnected mechanically and intersealed with the diaphragm and having a depending pin 'V is encased in ice.

28 which engages the point of the valve 22. A reticulated or perforated cap-like guide 28 is carried by the buffer plate 21 and telescopes over the upper end of the sleeve As will be understood from the drawing, the invention proposes a diaphragm of comparatively large area operating directly on a small needle valve which is so constructed and mounted as to be practically frictionless. These features of themselves tend to make the expansion valve super-sensitive and enable it to hold super-heat within very narrow limits.

In order to obtain the desired operating characteristics and yet avoid the use of differential bellow or differential diaphragm arrangements and to have the desirable small size and simplicity of structure, the present invention proposes to employ a charging refrigerant in the power element having a vapor pressure curve lying below that of the system refrigerant and combine a loading spring 29 with the diaphragm in such manner as to make it possible to obtain an equilibrium. The loading spring 29 applies a constant force to the diaphragm l5 tending to flex the same in the same direction as pressure in the chamber l8. The force which the spring applies to the diaphragm is determined by reference to the two vapor pressure curves and the effective area of the diaphragm. In the construction illustrated the loading spring 29 is disposed in the outlet chamber l4. and has its upper end abutting a fixed abutment plate 30 secured to the valve body by means of a split snap ring 3|. The spring 29 encircles a connecting shell 32 and has its lower end abutting an outwardly directed flange 33 provided at the lower end of this connecting shell. The connecting shell, while open at its lower end, has an upper end plate 34 which is secured to the diaphragm by being clamped to the parts that make up the bufier plate 21.

While the area of the diaphragm I5 is large in relation to the size of the valve 22, the expansion valve as a whole, including the diaphragm I5, is small and consequently the pressure chamber |8 is of small volume. The small volume of the pressure chamber. makes it practical to employ a small bulb -B, which, nevertheless, has a capacity or volume greater than the combined volume ofthe pressure chamber l8 and the capillary tube C. With this relation between the pressure chamber l8, capillary tube C, and bulb B of the power element, the power element may be and is, so charged with refrigerant or volatile liquid that the refrigerant will always have the exposed surface thereof from which evaporation occurs located or disposed within the confines of the bulb B. This has the important advantage of insuring that the bulb B is in control at all times and under all conditions and this even though the expansion valve In other words, the valve body may be placed in an ambient temperature lower or higher than the bulb temperature without adversely affecting the operation.

Provision is made for adjusting the super-heat range of the valve and resides in the provision of anadjustable spring which engages the diaphragm and opposes or bucks the action of the pressure in the pressure chamber l8. In the valve construction here shown this spring 35 is located in concentric relation to .the loading spring 29 and preferably is disposed within the connecting shell 32 and in surrounding relation to the sleeve I. The upper end of the spring 35 bears against sufficient.

gage the underside of the adjustable abutment the end plate of the connecting shell 32 and consequently is directly mechanically related with the diaphragm IS. The lower end of the spring 35 bears on an adjustable abutment ring 36 which is shiftable along sleeve ll under the control of suitable means. Preferably the means for adjusting the abutment 36 and consequently varying the force of the spring 35 and increasing or decreasing the super-heat includes a plurality of push pins 31 which extend through and are slidably interfitted with openings 38 provided in the ported partition around the outside of the sleeve ll. Any suitable number of these push pins may be provided, although usually three are The upper ends of the push pins en- 1 36. The lower ends of these pins rest on a shiftable plate 39 which is centrally apertured and swivelly interconnected with an adjusting screw 40, the center aperture of the plate fitting over a reduced extension of the screw and the portion of the underside of the plate which surrounds the center opening engaging ashoulder on the screw. The screw 40 has its threaded portion 4| threadedly engaged with the internally threaded portion of a hexagon nut 42 which is threaded into the lower end of an opening 43 provided in the valve body below the ported partition ID. The shank .of the screw works through packing 44 compressed by a follower 45 threadedly engaged with a gland 46 provided on the nut, and in all adjustments of the screw the lower end of its shank projects below the follower 45. The lower end portion of the screw may be provided with flats 41 to facilitate its manipulation by a suitable tool. A cap or bonnet 48 is threadedly interconnected with the gland 46 and provides an enclosure for the screw. By removing the cap or bonnet 48 and turning the screw a superheat may be increased or decreased as desired. The valve shown has an adjustable super-heat range between and 35 degrees Fahrenheit. By removing the hexagon nut 42 and the closure nut 26, th; valve assembly may be readily removed and the valve seat replaced or changed if desired.

An expansion valve of this character is very simple in its operation. Warming of the bulb B caused by increased load on the evaporator increases the pressure in the power element of the expansion valve and in the pressure chamber 18} thereby flexing the diaphragm l downwardly and having the needle valve to open position. The resulting increased flow of the refrigerant cools the refrigerant coil E and the expansion valve bulb B, thereby decreasing the pressure in the pressure chamber l8 and allowing the spring 33 to close the valve 22.

As previously stated, the diaphragm I 5 constitutes a wall of the outlet chamber into which the refrigerant directly flows as it issues from the orifice of the valve seat. The refrigerant in the outlet chamber is in contact with the diaphragm and has a cooling effect on the refrigerant orvolatile liquid in the pressure chamber It on the opposite side of the diaphragm so that as the valve 22 opens, the pressure in the chamber I8 is momentarily reduced and a closing movement is imparted to the valve 22 thereby setting up a self-modulation or dampening action of the valve which improves the operation of the system. The valve maintains a constant superheat over a wide range of evaporator temperatures. The power element is so constituted as to obtain an absolute shut-01f of the valve on the off cycle. This permits operation of the lower super-heat at normal operating pressures without flooding back on high evaporator temperatures. The use of a single diaphragm of large area together with the small amount of friction present in the valve 22 results in a very close valve regulating action.

While I have shown and described one construction in which the invention may be advantageously embodied, it is to be understood that the construction shown has been selected merely for the purpose of illustration or example and that various changes in the size, shape and arrangement of the parts may be made without departing from the spirit of the invention or the scope of the subjoined claims.

The invention claimed is:

1. A thermostatic expansion valve of the character described comprising a valve body having an inlet and an outlet, a valve seat interposed between said inlet and said outlet, a valve cooperable with said seat to regulate flow therethrough, said valve body having an outlet chamber on one side of said seat, a diaphragm interrelated with the valve body and interconnected with the valve, means co-acting with the diaphragm to define a pressure chamber, a capillary tube and bulb connected to the pressure chamber and co-acting therewith to provide the power element of the valve, said power element containing a charging refrigerant adapted to operate in vapor phase under same conditions of state as the system refrigerant and having a vapor pressure curve lying below that of the system refrigerant, a loading spring disposed in said outlet chamber and co -acting with the diaphragm to supplement the action of pressure in said pressure chamber, and an adjustable spring also disposed in the outlet chamber and engaged with the diaphragm to oppose the action of pressure in said pressure chamber and thereby control the super-heat in the system with which the valve is associated.

2. An expansion valve of the character described comprising a valve body having an inlet and an outlet, a ported partition interposed between said inlet and said outlet and having a valve seat, a valve cooperable with said seat to regulate flow tlie rethrough, said valve body having an outlet chamber on one side of said valve seat, a diaphragm interrelated with the valve body and interconnected with the valve, means co-acting with the diaphragm to define a pressure chamber, a capillary tube and bulb connected to the pressure ,chamber and co-acting therewith to provide the power element of the valve, said power element containing a charging refrigerant having a vapor pressure curve lying below that i of the system refrigerant, a loading spring disposed in said outlet chamber and co-acting with the diaphragm to supplement the action of pressure in said pressure chamber, an adjustable spring disposed in the outlet chamber in concentric relation to the loading spring and engaged with the diaphragm to oppose the action of pressure in said pressure chamber and thereby control the super-heat in the system with which the valve is associated, and means for varying the compression of the adjustable spring and comprising a shiftable abutment therefor, push pins engaged with said abutment, said ported partition having a plurality of openings through which the push pins are slidably fitted, and screw means operable from the exterior of the valve body for shifting said push pins.

3. A thermostatic expansion valve of the character described comprising a valve body having an inlet and an outlet, a ported partition inter-,

posed between the inlet and the outlet and provided with a valve seat, said valve body having an outlet chamber on one side of the valve seat and having an opening on the other side thereof, a valve cooperable with the valve seat for regulating flow therethrough, a diaphragm interconnected with the valve body, means co-acting with the diaphragm to define a pressure chamber, a capillary tube and bulb connected to the pressure chamber and containing a volatile fluid expandible and contractible under the influence of variations in temperature to which the bulb is subjected, means operatively interconnecting the diaphragm and the valve, a spring disposed in the outlet chamber and co-acting with the dia-' phragm to oppose the action of pressure in the pressure chamber and thereby vary the superheat, an afiustable abutment disposed in the outlet chamber and engaged with said spring, a removable nut for said opening, a screw threadedly engaged with the nut and having one end located in the opening of the valve body and having the other end projecting exteriorly of the nut, a plate in the opening of the valve body engaged with the screw and shifted thereby, and push pins interconnecting the plate and the abutment, the ported partition having openings through which the push pins extend.-

4. An expansion valve of the character described comprising a valve body having an inlet and an outlet, a ported partition interposed between the inlet and the outlet and having a valve seat, a valve cooperable with said seat for regulating flow therethrough, said valve having an outlet chamber on the outlet side of said seat, a diaphragm of good thermaleconductivity interconnected with the valve body and forming a wall of said outlet chamber, means directly connecting the diaphragm and the valve, meanscoacting with the diaphragm to define a pressure chamber, a capillary tube and bulb connected to the pressure chamber and co-acting therewith to provide the power element of the valve, said power element containing a charging refrigerant adapted to operate in vapor phase under same conditions of state as the system refrigerant and having a vapor pressure curve lying below that of the system refrigerant, a loading spring disposed in said outlet chamber and co-acting with the diaphragm to supplement the action of pressure in said pressure chamber, an adjustable spring also disposed in the outlet chamber and co-acting with the diaphragm to oppose the action of the pressure in the pressure chamber, and

means co-acting with the adjusting spring to vary the force which it applies to the diaphragm and thereby vary the super-heat in the system with which the valve is associated.

5. A thermostatic expansion valve of the character described comprising a valve body having an inlet and. an outlet, a valve seat interposed between said inlet and said outlet, a valve cooperable with said seat to regulate flow therethrough, a diaphragm. interrelated with the valve body and interconnected with the valve, means co-acting with the diaphragm to provide the power element of the expansion valve, said power element containing a charging refrigerant adapted to operate in vapor phase under same conditions of state as the system refrigerant and having a vapor pressure curve lying below that of the system refrigerant, a loading spring disposed in said outlet chamber and co-racting with the diaphragm to supplement the action of pressure in said pressure chamber, and an adjustable spring disposed in the outlet chamber in concentric relation to the loading spring and en-'

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