US2410795A - Expansion valve - Google Patents

Description

Nov. 5, 1946," E. J. DILLMAN 2,410,795

EXPANSION VALVE, I

Filed Feb. '5. 1944 INVENTOR ,ATTORNY Patented Nora-5, 34 6 um'reo STATES rarer ormen- EXPANSION VALVE Earnest J. Dillman, Detroit, Mich, assignor to Detroit Lubricator Company, Detroit, Mich, a corporation of Michigan Application February 5, 1944, Serial No. 521,233

7 Claims. (cl. 62-8) This invention relates to new and useful improvements in expansion valves for controlling the flow of refrigerant medium to evaporators to be operated in extremely low temperature ranges.

An object of the invention is to provide a thermostatic expansion valve which will be sensitive in operationirrespective of extremely low refrigerant medium pressures in the evaporator.

Another object. 3 is to provide thermostatic means to move the valve toward closed position in order to amplify the force available from re frigerant medium pressures.

Another object is'to provide means for obtaining a dual or stepped superheat setting of the valve so that there can be a limit of maximum valve opening movement in the normal operating and the evaporator supplied out and distinctly an electrically operated shut off valve Id preferably of the solenoid type operable to stop the flow of refrigerant medium to the inlet l2 and controlled by the switch 3 such that the valve i4 is opened upon starting of the compressor l and is closed when the compressor motor 2 is deenergized. The outlet l5 from the valve casing I3 is connected by a refrigerant supply line or conduit it to the inlet of the evaporator'l. The valve casing I3 is of elongated tubula form having a longitudinal'bore extending from. the inlet 12 and separated by a valve seat member l'i into a strainer inlet chamber l8 and a 'valve chamber l9. In the chamber is there is a tubular strainer member of fine wire mesh which is attached to the inlet fitting member 2| and removable thereby from the chamber l8.

' The outlet i5 opens laterally fromthe chamber Figure 1 is a view in longitudinal vertical secpressor driven by an electric motor 2 controlled by an automatic switch 3, controlled by a liquid or vapor charged power element 4 having a temperature responsive bulb element 5 positioned in the space of which the temperature is to be controlled, the power. element 6 serving to stop and to start the motor 2 respectively upon the occurrence of the desired low and high tempera ture limits in said space. The compressor I has its inlet or suction side connected by a refrigerant return line or conduit 6 to the outlet end of a refrigerant medium evaporator I positioned in the space to be refrigerated- The outlet or pressure side of the compressor l is connected by a conduit 8 to a refrigerant condenser 9 which feeds into a tank or receiver ill. From the receiver ill the refrigerant liquid line or conduit It connects to an inlet I2 of the valve or body member. it of the thermostatic expansion valve. Intercalated in the liquid line ii there is i9 adjacent the valve seat member H and is connected to the inlet l2- by a passageway 22 which connects into the strainer chamber l8 and bypasses the passageway and valve port 23 through the seat member [1. In the bypass passageway 22 there is a flow restricting member 24 having a calibrated bleed port or orifice for minimum effective flow direct from the valve inlet to the valve outlet, the calibrated port being of say twenty'thousandths inchesdiameter. The port in member 26 can be still further reduced in size to further restrict flow through the bypass passageway 22 by means of a valve member 25 of needle type carried by a manually operable stem 26. justably screw-threaded, as at 21, in a casing bore which provides a valve chamber 28 intercalated in the passageway 22. Leakage of refrigerant medium around the stem 26 is prevented by packing material 29 and a packing gland 30. A screw cap or cover 3i houses the external end of the stem 25 and is removable fromthe casing it for access to the stem 26 to adjust the valve member 25. In the valve chamber l9 there is a valve member 32 having a conical metering valve. head 33 cooperable with the valve port 23 to regulate flow of refrigerant medium to the evaporator l. The valve member 32 is of rectangular cross section, see Fig. 2, so that its side edges engage the cylindrical wall of the chamber iii to guide the valve member in longitudinal movement toward and from the port 23. The member '32 has a transverse cylindrical aperture it therethrough which receives one end of a lever member 35, which end is preferably of substantially spherical form. Play or lost motion of the The inner end portion of stem 26 is ad.-.'

3. prevented by a, spring 35" on a spring-pressed abutment rod 38 guided in a longitudinal bore in the back or outer end portion of the valve member 32. The rod 38 projects from the valve member 32, as at 31, for engagement with an adjustable stop member 38 which is carried byan end closure member 38 for the chamber H. The stop member 38 is backed by a helical coil spring 48 which is limited in its expansion and held under compresson by lost motion stop members, as at 4 I. The stop member 38 is adjustable longitudinally of the chamber i8 by a stem 42 adjustably screwthreaded, as at 43, in the closure member 39. The stem 42 may be screwed inward to engage the stop member 38 with the projecting end portion of rod 31 to seat the valve head 33 and close the port 23 or may be positioned such as to position the stop member 38, as shown, in which it limits the maximum opening movement of the valve memberfor the desired operating range of the valve and evaporator. The resistance of the spring 40 is such that the valve member 32 may have opening movement beyond its limit establishedby the stop member 38 for temperature ranges of the valve and the evaporator above the desired operating range.

The lever member 35 extends through a side wall opening 44 in the casing l3 and laterally of i the valve member 32, The opening 44 is closed by an annular supporting member 45 carrying a flexible metal bellows member 48 which is hermetically sealed at one end to the supporting member 45 and at its other end, as at 41, to the lever member 85. The member 48 has upstandlng spaced ears or posts 48 positioned at opposite sides of the lever member 38 and which support a pivot pin 49 on which the lever member 35 is jcurnaled or fulcrumed. The supporting member 45 is clamped to the'casing I3 by a downward facing annular shoulder in the tubular stem 58 of a T-shaped hollow housing member 8|, which is tightly clamped to the casing l3 by bolts 82. Packing or sealing rings 53, 54 are interposed respectively between the supporting member 45 and the casing l3 and the housing member 8| to seal the opening 44 and the stem 88.

The lever member 35, which serves as a reciprocal motion transmitting thrust member for operating the valve member 32, has its external endportion 88. terminating in the housing member El and provided with oppositely facing conical sockets 88, 81 which are concentrically aligned with the hollow cylindrical arms 88, 88 respectively of the housing member 8|. Carried by the arm 88 there is a thermostatic actuator 88 comprising acup-shaped casing 8| having an expansible contractible wall or closure member 82 facing the socket 88. The casing 88 is connected to and supported from the arm 88 by a thin walled tube 83 of heatflow resisting material, such as stainless steel. The movable wall member 82 is connected to the lever end portion 85 by a thrust member 84, preferably a two piece rod of adjustable length reciprocally supported in a guide ring 88 carried by the casing so. The thrust member 84 has one end secured to the member 82 and has its other end seating in the socket 58. Resilient damping fingers 88 are carled by the gu de ring 85 and frictionally engage the rod 84. The pressure chamber 81 formed within the casing 8| by the member 82 is connected by a tube 88 of capillary or small bore to a bulb element or feeler member 88 which is clamped in intimate heat exchange relation to the evaporator inlet line or conduit 18, preferablyadjacent the evaporator inlet. The bulb element 89 is charged with a minute quantity of volatile liquid having a steep pressure-temperature curve in the extremely low temperature operating range of the evaporator, such a liquid being for example ethane. The use of a minute quantity of liquid or so-called gas charging of the thermostatic actuator serves to limit the pressure exerted on .the wall member 82 and by the actuator 88 at of 110 F. below zero to'l20 F. below zero. The

chamber 81 contains the usual spring 81- held under compression between the end wall of easing 8| and the movable wall 82 and tending to hold the rod 84 in engagement with the lever end 55. Cooperable stop members 81 and 81 rigid respectively with the casing 8| and the wall 82 serve by their engagement with each other to limit expansion of the chamber 81. The actuator is opposed by a thermostatic actuator 18 having a cup-shaped casing 1i closed by an expansible contractible wall or movable member 12 which faces the lever member socket 51, the easing H being carried by a thin walled tube 13 of.

heat flow resisting material, such as stainless steel, which extends from the housing arm 59.

The wall member 12 is operatively. connected to the lever member 35 by a thrust member 14 which may be a two piece expandably adjustable rod having one end secured to the member 12 and having its other end seating in the socket 51.

Surrounding the thrust member 14 and apertured of the actuator 18 and determines the superheat setting of the valve in the operating range of the evaporator. The casing H and member 12 provide a pressure chamber 18 which communicate through a tube 19 of small or capillary bore with a bulb element or feeler member-88 which is clamped in intimate heat exchange relation to the suction line 8 adjacent the outlet of the evaporator I. The bulb element 80 is charged with a minute quantity of volatile liquid such that the actuator 18 is gas charged, the liquid preferably being ethane and being in such minute quantity that at temperatures above the operating 'range of the evaporator I the liquid will be in gas phase and thereby have its force limited which acts on the Wall member 12 and which is exerted by the actuator. 18 to move the valve member 32 toward 'open position. The chamber I8 contains the usual spring i8 tending to hold the rod 14 in engagement with the lever end 88 and held under compression between the casing H and the movable wall 12. Expansion of the chamber 18 is limited by the cooperable ture of the bulb element 80 is sumciently higher than the temperature of the bulb element 69 such as to overcome the force of spring 16. A removable plug 8| closing an aperture in the wall of tube i3 permitsaccess to the abutment member l1 for adjustment of the force of spring it and, therefore, the superheat setting of the valve.

The operation of the refrigerating system and of the expansion valve when embodied therein is as follows: Assuming that the evaporator I is at room temperature or a temperature well above its operating range and that the temperatures of the bulb elements 69 and 80 have equalized, the switch operating power element l, due to the bulb element 5 being at a temperature above the desired temperature of the space containing the evaporator I, will have closed the switch 3. Therefore, upon closure of the circuit at the switch 3 the motor 2 will be started in operation and'the valve I l will be energized and opened. The operation of the compressor I .by the motor 2 will withdraw refrigerant medium which is at high back pressure from the evaporator l and discharge the same to the condenser 9 and receiver H) for flow through the liquid line H and the open valve It to the strainer chamber I8. Since the valve head 33 is seated and closing its port 23 due to the force of spring 16, there will be a minimum restricted flow of refrigerant medium through the bypass passageway 22 and the calibrated orifice member 24 to the outlet I5 and thence via conduit i6 to the evaporator I. The refrigerant medium evaporating in the conduit is will reduce the temperature of the bulb element 69 and when the gas pressure in chamber 67 decreases below the differential force of spring It, the actuator ill will overcome the lesser force of the actuator 60 and act through the lever thrust member 35 to move the valve member 32 toward open position; As refrigerant medium feeds through the port 23, the temperature of the bulb element69 will be further decreased thereby still further reducing the force of the actuator 60 so that the actuator i0, which is unaffected by this first flow of refrigerant medium, will move the valve member 32- to its maximum open position limited by the stop member 38. As the pressure in the inlet to the evaporator" l is further decreased by the compressor 6, the force exerted'by the actuator M will be still further decreased so that the gas in chamber 18 will exert sufficient pressure due to the relatively high temperature of the superheated refrigerant afiectingthe bulb B0, to overcome the spring d0 so that the valve head 33 will be moved to wide open position beyond the limit of the stop 38 thereby permitting substantially unobstructed flow through the port 23. The compressor I will therefore be permitted to operate efiiciently during the period when the evaporator l is-be'ing pulled down to its operating pressure range. As soon as the refrigerant medium in the evaporator l cools the bulb element 83 to a temperature such that the force exerted by its thermostatic actuator H! becomes less than the sum of the forces exerted by the actuator 66, the superheat spring 16 and the spring dd, then the spring will expand and move its limiting members toward engagement at Al. Expansion of the spring to will move the valve member 32 toward its seat, thereby reducing the rate of flow of the refrigerant medium to the evaporator 'I. The spring fill wiil continue to exert its force to close the valve member 32 until the temperature of the bulb element 80 has been reduced to the point where the stop members engage each other at.

' hold the rod end 37 in engagement with the stop member 38 which determines the maximum open position of the valve member 32 in the operating range of the evaporator. This maximum limit determined by the stop 33 and spring All) for the open position of the valve in the evaporator operating range serves'to reduce surging of the system which would be caused by excessive flow of refrigerantmedium through the valve port 23. When the evaporator l becomes completely refrigerated by the supply of refrigerant medium thereinto, such that evaporation is occurring to a point adjacent but on the evaporator side of the bulb element at, then the bulb elements 59 and 30 will cooperate t0;reg'ulate the opposing pressures in the thermostatic actuators 60 and 10 so as to throttle the valve member 32 for the necessary flow of refrigerant medium through the port 23 to keep the evaporator l flooded throughout its length. The system will continue in operation with the compressor i running until the temperature of the space refrigerated by the evaporator 1 decreases to the desired temperature at which power, element Q will open the switch 3 and deenergize the motor 2 and the valve it to stop flow of refrigerant medium to the valve inlet 02. It may be noted that the minimum flow permitted through the orifice member 25 will aid in preventing surging due to complete closure of the valve head 33 during the operation of the compressor land which may result from frictions at the extreme low temperatures of operation of the valve.

What is claimed and is desired to be secured by Letters Patent of the United States is:

1. The combination with a refrigerant evapobypassing said seat member, an orifice member determining the minimum flow to said outlet and positioned in and restricting flow through said bypass passageway, a needle valve cooperable with said orifice member to throttle the flow through the orifice in said orifice member, said casing having a side wall opening positionedat the side of said valve member, a motion transmitting member connected to ,and for actuating said valve member and extending through said opening, means sealing said opening around said transmitting member, a housing mounted on said casing and surrounding the exterior end portion of said transmitting member,- a fluid charged thermostatic actuator carried by. said housing and having a. bulb element responsive to temperature of the refrigerant medium adjacent the inlet to the evaporator, a rod connecting said actuator to said transmitting member to move said valve member toward closed position upon temperature increase of said bulb elcm nt,'a fluid charged thermostatic actuator carried by said is no longer opposed by the spring Ml, will now.

temperature of the refrigerant medium adjacent the outlet of the evaporator, a rod connecting said second-named actuator to said transmitting member to move said valve member toward open position upon temperature increase of. said secend-named bulb element, a superheat determining spring opposing opening of said valve memher by said second-named actuator: and means closing the other open end of said casing and determining the maximum opening of said valve member in its operating range.

2. An expansion valve for controlling the flow of refrigerant medium to an evaporator to be operated at extremely low temperatures, said valve being controlled in accordance with the diflerence in the refrigerant medium temperatures adjacent the inlet and outlet of the evaporator and comprising a tubular valve casing having an inlet andanJoutlet, a valve seat member in said casing and having a-valve port,-a valve member reciprocal in said casing and cooperable with said 'seat member, said casing having a restricted passageway bypassing said port and leading from said inlet to said outlet, said casinghaving a side wall opening at the side of said'valve member, an annular supporting member, sealed to said casing concentric with said p ning. a motion transmitting lever member extending through said supporting member and said opening and having one end engaging said valve member, means pivotally securing said lever-member to said supporting member, a flexible closure member surrounding said lever memher and sealed to said supporting member and to said lever member, a T-shaped housing member'having its stem receiving the external end of said lever member, means clamping said stem to said casing around said opening, said external lever end having alined sockets concentric with and facing the arms of said housing member, tubular supporting members alined with each other and extending one from each of said arms, thermostatic actuators secured one to each of said arms and each having a pressure chamber with a movable wall facing one of said sockets,

thrust rods extending between said movable walls and said sockets, bulb elements containing a minute quantity of volatile liquid and communicatively connected one to each of said pressure I chambers, said liquid having a steep pressuretemperature curve relative to the pressure-temperature curve of the refrigerant medium in the low temperature operating range of the evaporator so as to exert a greater pressure per degree of temperature change than is exerted by the refrigerant medium, one of said bulb elements being adapted to respond to the refrigerant medium temperature adjacent the inlet to the evaporator and tending upon temperature increase to cause valve member closing movement and the other of said bulb elements being adapted to respond to the temperature of the refrigerant medium adjacent the outlet of the evaporator and tending upon temperature increase to cause valve member opening movement, and a spring resisting valve -member opening movement by the actuator having said other bulb element thereby to determine the superheat setting of the valve. 1 3. An expansion valve for controlling the flow of refrigerant medium to an evaporator to be operated. at extremely low temperatures, said valve being controlled in accordance with the 'diflcrenoc in the refrigerant medium temperavalve member is closed, means responsive to temperature of the refrigerant medium adjacent the evaporator inlet for movingsaid valve member toward closed position upon temperature increase of the refrigerant medium, a gas-charged thermostatic actuator having a bulb element containing a minute volatile liquid charge having a steep pressure-temperature curve in the operating range'of the evaporator, said thermostatic actuator being operatively connected to said valve member and acting upon temperature increase to move said valve member toward open position, a superheat determining spring opposing said thermostatic actuator, and a spring operable to stop in an open position the opening movement of said valve member in the operating range of the evaporator, said stop spring being overcome by said thermostatic actuator at temperatures above said operating range thereby to provide wider opening of said valve member. 1 4. A thermostatic expansion valve for controlling flow 'of refrigerant medium to an evaporator in accordance with the difference in the refrigerant medium temperatures adjacent the inlet and the outlet of the evaporator, comprising a valve casing having a pasageway therethrough with a valve seat, a valve member having a lateral opening and being cooperable with said seat, said casing having a side wall aperture 35 alined with said lateral opening, a lever extending through saidaperture and having one end positioned in said lateral opening, means holding said lever end Qagainst lateral play in said opening, a T-shaped housing having its stem end secured and sealed to said casing around said aperture, said lever extending into said housing and having oppositely directed sockets alined with the arms of said housing, tubular supporting members in concentric relation and extending one from each arm of said housing, a fluid charged thermostatic actuator mounted on the free end of one of said supporting members and having a bulb element adapted to respond to refrigerant medium temperature adjacent the evaporator inlet, a rod seating in one of said sockets and connected to said actuator to urge said valve member positively toward closed position upon temperature increase of said bulb element, a fluid charged thermostatic actuator mounted on the free end of the other of said supporting members in opposition to said first-named actuator and having a bulb element adapted to respond to refrigerant medium temperature ad- .iacent the evaporator outlet, a rod seating in the other of said sockets and connected to said second-named actuator to urge said valve member positively toward open position upon tem-v way having a valve seat, a valve member cooper-' tor having a bulb element responsive to the temperature of the refrigerant medium adjacent the inlet to the evaporator and acting on temperature decrease to permit said other actuator to move said valve member toward open position, said other actuator having a bulb element responsive to the temperature of the refrigerant medium adjacent the outlet of the evaporator, said actuators being so constructed and charged as to exert equal and opposite forces on said lever end for equal temperatures of said bulb elements, a

superheat determining spring surrounding and acting through said second rod to oppose opening movement of said valve member by said other actuator, said-casing having a bypass passageway around said seat for flow of refrigerant medium to cool said first-named bulb element so that said other actuator can open said valve member, and stop means including a spring and. engageable by and limiting the opening movement of said valve member, said stop means spring having a resistance which is overcome by said other actuator during the starting period of evaporator operation so that said valve member can have opening movement beyond the limit of said stop means.

6. In a refrigerating system, the combination with a compressor, a condenser and an evaporator communicatively connected in circuit, of a thermostatic expansion valve comprising a valve casing having a passageway therethrough containing a valve seat, said passageway having its inlet connected to said condenser and having its outlet connected to the inlet of said evaporator,

a valve member cooperable with said seat to throttle flow of refrigerant medium from said condenser to said evaporator, a lever operable to move said valve member, a fluid charged thermostatic actuator facing said lever and having a bulb element responsive to temperatureof the refrigerant medium adjacent the inlet to the evaporator, a rod connecting said actuator to said lever such that temperature increase of said bulb element will tend to close said valve member, a

i0 fluid charged thermostatic actuator facing said lever and said first-named actuator and having a bulb element responsive to temperature of the refrigerant medium adjacent the outlet of the evaporator, a rod alined with said first-named rod and connecting said second-named actuator to said lever such that temperature increase of said second-named bulb element will tend to open said valve member, a superheat determining spring acting on and through said second-named rod in opposition to'opening of said valve member by said second-named actuator, and means to bleed refrigerant medium from said passageway inlet to said passageway outlet to cool said first-named bulb element so that said secondnamed actuator can overcome said spring and open said valve member.

, 7. A thermostatic expansion valve for controlling fiow of refrigerant medium to an evaporator, comprising a valve casing having a pas sageway therethrough with a valve seat, a valve member having a lateral opening and being cooperable with said seat, said casing having a side, wall aperture alined with said lateral opening, a lever extending through said aperture and having one end positioned in said lateral opening, means holding said lever end against lateral play in said opening, a T-shaped housing haw ing its stem end secured and sealed to said casing around said aperture, said lever extending into said housing and having opp'ositelydirected sockets alined with the arms of said housing, tubular supporting members in concentric relation and extending one from each arm of said housing. a fluid pressure responsive actuator mounted on the free end of one of said supportingmembers, a rodseating in one of said sockets and connected to said actuator to urge said valve member positively toward closed position upon pressure increase, a fluid charged thermostatic actuator mounted on the free end of the other of said supporting members in opposition to said first-named actuator and having a bulb element adapted to respond to refrigerant medium ternperature adjacent the evaporator outlet, a rod seating in the other of said sockets and connected to said second-named actuator to urge saidyalvg member positively toward open positionfipon temperature increase of said bulb ele ment, and a spring surrounding and acting on manner an I I

Images