US1978709A - Expansion valve regulating mechanism for refrigerating systems - Google Patents

Description

Oct. 30, 1934. w Q HILL 1,978,709

EXPANSION VALVE REGULATINGMECHANISM FOR REFRIGERATING SYSTEMS Filed oct. 1. 1951 Patented 30, 1934 EXPANSIN VALVE REGULATING MECHA- NISM FOR BEFRIGEBATING SYSTEMS.

g william c. mu, Denham, men. application october 1, 1931, serial No. 566,285

14 claim..

This invention relates to expansion valves oi the type commonly used in mechanical refrigeration systems, and has for one of its objects provision of a greatly improved expansion valve 6 having especial utility when arranged to independently control the supply of refrigerant to one of a plurality of evaporators all oi' which are incorporated in the same refrigerating circuit, that is, supplied by the same compressor with 10 refrigerant which returns thereto.

Another object of this invention is the provision of such an expansion valve as will maintain one of a plurality of so arranged cooling units the .temperature of the other units, and semiindependently of the back-pressure in the evaporator. As is well known, most of such expansion valves, when incorporated in a mechanical re- !rigerating circuit of the usual type comprising a compressor, condenser, expansion valve and evaporator, rely for their operation upon the rise and fall of back-pressure generated in the evaporator or expansion tank, by the presence therein or absence therefrom of sumcient gase` ou's refrigerant at sumciently high pressure to permit closure or opening of the valve under' the influence o1 one of a pair of opposed springs or the like. When a number of evaporators, 3' each having its own expansion valve, are suphowever, it becomes a practical impossibility. to

such evaporators at variant tempera- Y tures (which is frequently a desideratum) as 'theV back pressure in such unitstends to equalize,

a dueto their connection to. a common return line.

It is an object of this invention to so control the operation of each expansion valve, indei pendently of the back pressure in its evaporator, that such units may be -maintained at any desired variant temperature.

It is also an object of this invention to provide"improved electrical controlling meansvfor the operation of an expansion valve.

i AA still fm'ther object of this invention lies in the provision of means for preventing undesired opening of the expansion valve of a refrigerating system when the pressure on its low side falls below the reduced point at whichthe valve normally opens.

Other objects and advantages will be apparent -from the following description, wherein refer enceismadetotheaccompanyingdrawing Y .illustrating preferred embodiments of my inven-` sstiornand wherein similar reference numerals at any desired temperature,V independently oi plied from -a single compressor and condenser,-

' designate similar parts throughout the several views.

In the drawing:

Figure 1 is a fragmentary schematic of a refrigerating system, yshowing a plurality of' cooling units connected to refrigerant supply and return lines.

Figure 2 is a sectional and partly diagrammatic view of an expansion valve incorporating one form of my invention.

Figures 3, 4, 5, 6, and 'I are views similar to Figure 2 of expansion valves incorporating somewhat modiiied forms of my invention.

Referring now to the drawing, reference character l0 represents a refrigerant supply pipe, on the high side of a vcirculatory refrigerating system, and 11 a. plurality of expansion valves and their 'appurtenant pipes` located in suitable and desired positions therealong, for controlling the supply of refrigerant to separate evaporators- Since this invention concerns itself entirely with lexpansion valve constructions. no attempt is made to illustrate'or describe in detail the other portions of a refrigerating system, further than is necessary to render clear the present disclosure. It is to be understood moreover that 'such refrigerating apparatus may be of any de- Vsired form and construction, and that my improved expansion valve might 'also be adapted to numerous other uses. Y v

In the construction shown in Figure 2, the valve 12 is normally/intained in opened position by the compression spring 13, which urges downwardly the diaphragm 14,.the central oiset sylphon portion 15 of which is engaged by the stem 16 of the valve 12. The valve is urged toward closed position by the spring 17, which is of course weaker than the spring 13. Refrigerant enters the chamber 18 through the supply tube 19, which is connected to the main supply line 10, and passes through-the valve orifice 20 to the chamber 21 immediately beneath the diaphragm 14, whence it is conducted tothe evaporator by the tube 22. It will bev obvious that when the pressure-rises sufficiently in the 10 chamber 21, due tothe boiling of the refrigerant in the evaporator, the tendency of the thus generated back pressure is to lift the diaphragm 14 against the'force o'f the spring 13, which-in an ordinary expansion valve construction would l as the pressure in the chamber 21 falls sumciently, the valve reopens, as the spring 13 then overcomes the opposing force of the spring 17. This is frequently undesirable, as it may be desired to maintain the evaporator controlled by this particular expansion valve at a higher temperature than the possible To prevent reopening of the valve, despite the decreasing back-pressure, until a desired temperature hasibeen attained, I provide the diaphragm 14 with the above mentioned oset exible bellows or sylphon portion 15, against which the valve stem engages. A sleeve 23 surrounds such sylphon portion, and its bottom is secured to the diaphragm. The sleeve is provided with an end can v24 at its upper extremity, which may be screw-threaded therein to permit adjustment, as shown in Figure 2. The upper end of the ilexible bellows portion 15 of thediaphragm 14 is closed by a relatively stiff buffer plate 25, which receives the thrust of the valve stem 16. It Will be apparent that, due to the flexibility of the bellows 15, in order to open the valve, or to maintain the same in opened position, the downward movement of the spring 13 must be transmitted through the buffer plate 25, as the downward force exerted by spring 13 on the main diaphragm 14 is rendered relatively ineffective by the interposition of the bellows 15 between the diaphragm and-valve stem.

Between the end cap 24 and the bull'er plate25 y,

incorporated in the thrust-transmitting member is adapted when heated to swell the plates 26 sufficiently to establish contact between plates 24 and 25, thereby rendering the spring 13 operative to open the expansion valve, provided the pressure in the chamber 21 is sufliciently reduced. The exible conductors 29 may connect the heating 'element with a thermostat (not shown) in the refrigerated zone, or other suitable outside controlling means, `automatic or otherwise. If desired pads or spacers 45 formed of material of poor thermal conductivity may be used to separate and insulate the buffer plate 25 and the adjacent one of the plates 26 on the one hand and the end cap 24 and another one of the plates 26 on the other side.

It will be apparent that as long as the heating element 28 is energized and the plates 26 distended, ,the valve will function in the normal manner, but that when the plates of the thrusttransmitting member are allowed to collapse, due to the de-energization of the heating element, the valve will remain closed, since the thrust of the spring 13 is then ineffective to open it. yIn this manner a thermostat may be arranged to so control the functioning of the expansiotn valve that the valve may be allowed to remain closed, independently of falling pressure on the low side, until the temperature in the refrigerated zone reaches any desired point at which the thermostat may be set; and this though the evaporator may be one of several connected to a common return line, as 30, Figure 1.

In Figures 3, 4, 5, 6 and 7 are illustrated somewhat modified forms of my invention, all of which are productive of similar results. In Figure 3 is shown an expansion valve normally controlled in the conventional manner by a thermostat comprising the bulb 3l, connected tube 32 and bellows 33, in which may be trapped a suitable volatile fluid in the well known manner. The thrust of the bellows 33 is transmitted to the thrust plate 14 through the crown cap 24g. The thrust plate 14a will be seen to be centrally provided with an oilset ilexible sylphon portion 15a, similar to the portion 15 previously described, but extending in the opposite direction. A relatively stii buer plate 25a similarly closes the end of the sylphon portion and bears against the stem 161i. A thrust-transmitting member may be provided partially housed within the sylphon portion 15, and comprising a substantially cylindrical cupped portion 27a closed at its upper end by a distortable outwardly convexed metallic cap 26a. A heating element 28' is similarly `provided within the thrusttransmitting member, which, when heated, is

adapted to expand the air or other fluid contents of the thrust-transmitting member, to upwardly distend the cap 269. It will be seen that the'pressure exerted by the bellows 33 can only be made effective to` open or maintain in open position the valve 12a when the heating element 28 is energized and the thrust-transmitting member expanded to operatively connect the buffer plate 25=l and cap 24-, upon which the thrust of the bellows is directly imposed. The exible leads 29 may connect the electrical heating element with any suitable outside controlling means, in the manner set forth in connection with the first described embodiment, and it will be seen that when the heating element is energized the operation of this form of my invention is also similar to that of an ordinary expansion valve; and accordingly need not again be described. The parts of such conventional portions of the device are numbered similarly to those of the first described embodiment, with the addition of a exponents to the reference characters. The construction shown in Figure 4 di'ers from that of Figure 3 principally in that the combined chamber 33b and diaphragm 14b serve the function performed, as to the construction shown in Figure 3 by the thrust plate 148L and the bellows Figure 4 shows another somewhat modied form of my invention in which a conventional type of thermostatic control may be provided, governed by the bulb 31", tube 32b and chamber 33', which is closed by the diaphragm 14b to which the chamber is sealed by the ilexible bellows 34. Such thermostatic controlling means may be rendered normally ineffective to open the expansion valve in a similar fashion, as by centrally providing the diaphragm 14h with an o'set flexible portion lb'closed by a buffer cap 25h, against which the valve stem 16b engages. Secured to and movable with the diaphragm 14b surrounding the sylphon 15b is a light but rigid housing 23h, which is provided with an enlarged cylindrical upper extremity serving as a casing for the bellows 27h, which constitutes an auxiliary thermostatic element and is connected by means of the tube 29'J to the bulb 35. The bellows 27b will be seen in'this embodiment to upon the diaphragm, exerted within the thermostatic phamber 33 by engagement of the end caps 26 ofthe bellows with theo buffer plate 25" and the upper' end of the housing 23, is the lexpansion valve operable in 4the-normal manner,

that is, under the control of the thermostatic bulb 31" as to the opening of the valve.

As shown in Figure 5, the expansion valve may be controlled by a thermostatic bulb 31, which is in turn controlled by an electrical heat- The thrust of the spring 13 is 'in this embodiment imposed directly upon thediaphragm 14, but is rendered ineilective to open the valvel under normal conditions by the offset sylphon portion 15, against the buffer plate of which the valvel stem 16 engages. 'Ihe thermostatic chamber 33 may. be closed by the same sylphon. 15, as there shown. and is connected to the bulb 31 4by the tube 32. They end or buiIer plate 25 vof the sylphon is normally urged upwardly and away from the end of thevalve stem by the coil spring 36. This spring may be positioned by an upwardly projecting boss or sleeve portion 37 carried by the diaphragm 14. The fluid within the connected bulb 31, tube 32 and chamber 33 is of such quantity and volatility that it cannot expand suillciently under Vnormal operating conditions to move the plate 25 downwardly into engagement with the valve stem, to permit opening of the valve 12, except whenrthe heating element 28 is energized to vsuillciently expand the con- `tents of the thermostatic system. It -will of course be obvious that the energization or otherwise of the bulb 31c may be regulated in the '38 formed in the' thrust plate 14d.

same manner as that provided as tov thebulbl v35 Vin the construction shown in Figure 4.

The modiiled form, shown in Figure 6 is also electrically controlled, and-the heating element 18 may be housed in a cupped central portion The thrust plate is connected to the housing 39 ot the valve by a ilexible bellows 40, and the downward force of the spring 13, tending to open the valve .12

againstthe tension'of the spring 17, must be exerted through the sylphon 15 and its buffer cap 25. l'Ihe ilexibility of the sylphon is'such', however, that sumcient pressure cannot be transmitted to accomplish opening or maintenance of the valve iny open Position unless the` air'or 'other fluid trapped' between thesyl- 'phon 15 and cupped portion 38 of the dia-- phragm is expanded, as by energiaation ofthe heating element 18. The plate 25 is normally urged away from the end of the valve stem by the spring 30; which is 'supported by a spider or cupped support 37 secured to the thrust plate 14. Actual separation of the plate 25 and the valve stem 16 may occur, dependent 'upon the degree of energization of the heating element 18. The operation ot the remainder of this embodiment of my invention seen to be analogous to the operation of the ments previously described.

As shown in Figure 7, a member in the nature' of a wedge, ale-26 may be interposed-between theendof-thevalvestemandthepressureresponsive diaphragm 14%', which may be moved tothe left. as viewed in thatll'igure, to so separate the complementarily wedge-shaped butler 25e carried by the diaphragm 14 from the valve stem as to render the latter non-actuatable by the former. 'I'he wedge `member 26 may be operable in any suitable manner, analogousv to one of those previously described, as by the bellows 27 connected thereto by the link 43, and the like functioning of the device to those previously described will be apparent.

As to eachof the suggested modified forms shown in .Figures v3 to 'l inclusive, pads of insulating or semi-insulating material similar to ,the pads described as to, the construction shown in Figure 2 may, if desired, be used to adequately separate the heat-energized parts from the adjacent cap and builer plates.

It will be apparent that by employing one or more of my improved expansion valves provided with Iauxiliary controlling means in the manner herein described, in conjunction with such an arrangement of independent cooling units as is ,diagrammed in Figure 1, it-is possible to govern with complete independence the temperature at 1 which each unit willbe maintained by its valve.

vrelatively to the seat, means connecting the valve member and actuating means, and-temperatureresponsive means for rendering such connectingl means ineffective.

2. In an expansion valve, a. valve seat, a valve member' movable relatively to the seat, actuating means Aincluding a movable pressure-responsive member for governing movement of the valve member, means forming a plurality l of parts4 connecting the valve. member. and actuating means to enable controlling the former bythe latter, and-temperature controllable means for preventing vmovement of one part of said connecting means by another to render said connecting means ineffective at desired times.

4 3. In combination with a circulatory refriger-- ating system including a plurality of evaporators', an expansion valve for independently controlling the ilow of refrigerant through each evaporator, each valve including av valve, seat, a

valve member movable relatively to the seat, a

movable diaphragm member for governing the ing the valve and diaphragm members to enable controlling the motivation of the former by the latter, and means subject to outside control for e.

preventing operation of said .connecting means.

4. In a circulatory refrigerating system including a plurality of evaporator-s, an expansion valve for controlling the admission of refrigerant to each evaporator, each valve including .a valve actuating of the valve member, means connectf member, a valve seat, a pressure-responsiveV member for moving the valve relatively' to its seat, meansconnecting vthe valve and valve actuating members, and means for rendering said connecting means ineective in response to temperatureconditions v temporarily prevailing in the area refrigerated by the evaporator controlled thereby, comprising a member forming part of said connecting means,4 and movable to break the continuity thereof, means responsive to temperature changes in said area for moving said member.

5. In a rerigerating system including an evaporator, an expansion valve controlling the admission cf refrigerant to the evaporator, means normally responsive to pressure variances in the evaporator for actuating the valve toward opened or closed position, means mechanically connecting the valve and its actuating means, and a member forming part Aof the connecting means and controllable in response to varying temperature conditions in the refrigerated area for breaking such mechanical connection to render the pressure-responsive actuating means inoperative to move the valve.

6. In an expansion valve, a valve member, means for actuating said valve, 'means connecting the valve and the actuating member, and temperature-responsive means for selectively breaking the connecting means to render the actuating means ineilective.

7. In combination with a refrigerating system having a cooled zone and an evaporator incorporated therein, an expansion valve member controlling the admittance of refrigerant to the evaporator, means normallyv responsive to the pressure on one side of the valve for actuating the same toward open or closed position, means connecting the valve member and actuating means, and means responsive to temperature in the cooled zone, for rendering the connecting means ineiective under desired temperature conditions therein.

8. In an expansion valve incorporating a valve member, a valve seat, means adapted to control the opening and closing of the valve, actuating means for the valve, and temperature-responsive means for automatically connecting and disconnecting the valve and its actuating means at desired times.

9. In an expansion valve, a valve member, a valve seat, a pressure-responsive member for moving the valve toward and from its seat,

means operatively connecting the valve and .l

and closure of said valve are regulated, andmeans operable independently of such pressure variations and rponsive to predetermined temperaturechanges within the refrigerated space 4served by said evaporator for positively closing the valve and preventing operation thereof by said pressure-responsive means. A

11. In combination with a circulatory refrigerating system including a plurality of evaporators, a valve appurtenant each evaporator and including a valve member, a seat therefor, means for efIecting the opening and closing movement of said valve conformably to variations in relative pressures within said refrigeration system and means appurtenant each valve and controllable independentlyof such relative pressures for preventing one of such pressures from inuencing operation of the valve, to thereby enable its positive maintenance in one position independently of such pressures. K

12. In combination with a circulatory refrigerating system including a plurality of evaporators, an expansion valve appurtenant each evaporator and including a valve member and a port relatively-to which the valve is movable, means subject to the influence of pressure variances acting upon said valve for controllingly so moving the valve member, and means controllable in*v response to temperature conditions in a zone served by the appurtenant evaporator for lpositively preventing the operation of thevvalve by such pressure variations and whereby the valve may be maintained in one position independently thereof.

13. The combination, with a plurality of spaces to be refrigerated, an evaporator in each space and a common circulatory refrigerant system connected to all of such evaporators, a pressure-regulated expansion valve controlling the flow of refrigerant iluid through each` evaporator, means associated with each of said valves for regulating the opening and closure thereof responsively to pressure variations in the system, and independent means responsive to thermal conditions within the space served by the appurtenant evaporator for rendering said pressure-responsive means inoperative to control movement of the valve.

14. 'In combination with a common refrigerant supply line and with a plurality of pressure- WILLIAM `C. HILL.

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