EP0504775A2 - Unterkühlungsstromregelventil für Kälteverfahren - Google Patents

Unterkühlungsstromregelventil für Kälteverfahren Download PDF

Info

Publication number
EP0504775A2
EP0504775A2 EP92104505A EP92104505A EP0504775A2 EP 0504775 A2 EP0504775 A2 EP 0504775A2 EP 92104505 A EP92104505 A EP 92104505A EP 92104505 A EP92104505 A EP 92104505A EP 0504775 A2 EP0504775 A2 EP 0504775A2
Authority
EP
European Patent Office
Prior art keywords
refrigerant
flow
valve
chamber
condenser
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP92104505A
Other languages
English (en)
French (fr)
Other versions
EP0504775A3 (en
Inventor
Pandu R. Cholkeri
Owen S. Smith
Carl N. Johnson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ranco Inc of Delaware
Robertshaw US Holding Corp
Original Assignee
Ranco Inc of Delaware
Ranco Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ranco Inc of Delaware, Ranco Inc filed Critical Ranco Inc of Delaware
Publication of EP0504775A2 publication Critical patent/EP0504775A2/de
Publication of EP0504775A3 publication Critical patent/EP0504775A3/en
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F25B49/027—Condenser control arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F25B41/24—Arrangement of shut-off valves for disconnecting a part of the refrigerant cycle, e.g. an outdoor part

Definitions

  • This invention relates to refrigeration systems and more particularly to vapor compression refrigeration systems wherein system refrigerant flow is variably controlled in response to sensed conditions.
  • Refrigeration systems for household refrigerators and freezers have heretofore been designed for low cost and high reliability, both of which require design simplicity together with a minimum number of parts.
  • Typical refrigerators or freezers employ a vapor compression system having an electric motor driven hermetic compressor connected in a circuit with a condenser, evaporator, an optional accumulator, and a refrigerant flow restriction between the condenser and the evaporator.
  • the flow restriction is almost universally a capillary tube sized for optimal system efficiency under a nominal set of operating conditions.
  • Such capillary tubes were designed for a constantly running refrigeration system operating at a single ambient temperature and constant load condition.
  • Capillary tubes used as the sole restriction offered the advantages of low cost and high reliability. They performed satisfactorily under operating conditions other than those for which they were designed, albeit at reduced efficiency.
  • a system operating under these idealized design conditions utilized the condenser to liquify high pressure gaseous refrigerant from the compressor and delivered it, as a saturated or slightly subcooled liquid, to the capillary tube.
  • the liquified refrigerant flowing through the capillary tube experienced a substantial pressure reduction on its way to the evaporator.
  • Refrigerant was vaporized in the evaporator as it absorbed heat from a system load.
  • the refrigerant then flowed to the compressor inlet as a low pressure gas.
  • the rate at which the system pressure equalized and the rate at which chilling commenced again depended upon the degree of flow restriction created by the capillary.
  • Capillary tubes sizes could be "loose” or “tight.” i.e. less or more restrictive, respectively.
  • the capillary tube was sized “loose” to allow the evaporator to flood quickly during compressor start up.
  • the "loose” capillary also allowed fast equalization of system pressure during the off cycle.
  • a principal advantage of a "loose" capillary design has been that fast pressure equalization enabled use of a low cost, low torque compressor motor for restarting the compressor after a short "off" cycle.
  • valves for blocking flow through the capillary tubes whenever the compressor turns off. These valves have been solenoid operated or have responded to changes in refrigerant pressure created by the compressor turning on and off. For example, see U.S. patent 4,267,702 issued May 19, 1981 to Houk. These kinds of valves did not modulate the refrigerant flows.
  • the present invention provides a new and improved, highly efficient household refrigerator or freezer wherein a refrigerant flow controlling valve is provided which modulates the flow of liquified refrigerant through an expansion device in response to sensed condenser outlet refrigerant temperature and pressure conditions in a highly accurate fashion, blocks refrigerant flow from the condenser when the compressor is off and yet assures system refrigerant flow at extremely high ambient temperatures to protect the system.
  • a flow control valve constructed according to preferred embodiments of the invention is associated with a vapor compression refrigeration system comprising a cyclically operated compressor, a condenser, and an evaporator between the condenser and the evaporator.
  • the refrigerant flow controlling valve is disposed between the condenser and the evaporator and comprises a housing defining a refrigerant flow chamber for receiving liquified refrigerant from the condenser outlet, valve seat structure defining a refrigerant flow port for communicating refrigerant from the condenser to the expansion device, and a refrigerant flow controlling valve assembly coacting with the valve seat structure to control the refrigerant flow from the refrigerant flow chamber to the expansion device.
  • the new flow control valve is so constructed and arranged that it accurately controls system refrigerant flow in response to subcooling, blocks refrigerant flow from the condenser when the compressor is cycled off and enables circulation of hot gaseous refrigerant under extreme high temperature ambient conditions.
  • the flow controlling valve assembly comprises a valving member movable into and away from engagement with the valve seat structure and an expansible chamber pressure actuator for moving the valving member.
  • the actuator has an operating fluid chamber containing a predetermined mass of vaporizable operating fluid in pressure and heat transfer relationship with refrigerant from the condenser outlet.
  • the actuator biases the valving member toward its closed position to prevent refrigerant flow through the port when the compressor is cycled off and has a movable operating chamber wall structure for operating the valving member to vary the flow through the expansion device in response to the condenser outlet refrigerant temperature when the compressor is operating.
  • the actuator operating fluid completely vaporizes at a predetermined relatively high condenser outlet refrigerant temperature (indicative of high ambient temperature) and the valve port is maintained open at condenser outlet refrigerant temperatures above the predetermined temperature.
  • valve is constructed and arranged to enable its calibration by controlled distortion after it has been fabricated. This assures reliable and accurate operation.
  • a valve seat supporting member forms a refrigerant flow chamber wall with a valve seat projecting from it. The seat supporting member is yieldable and is yielded to shift the valve seat location within the refrigerant flow chamber to a calibrated position.
  • the actuator comprises a thin, flexible stiffly resilient metal diaphragm defining a wall of the actuator chamber.
  • the actuator is disposed in the refrigerant flow chamber so that the diaphragm position is controlled by the refrigerant flow chamber temperature and pressure.
  • the valving member is attached to the diaphragm and defines a generally flat, pliant valving face having an area substantially larger than that of the flow port.
  • the preferred housing comprises first and second cup-like housing members hermetically joined to form the chamber between them, each housing member having a cavity surrounded by a peripheral flange and a conduit extending from the cavity.
  • the housing members are fixed with respect to each other at the flanges with the cavities confronting so the conduits form refrigerant flow chamber inlet and outlets.
  • the valving member is biased to an open position spaced from engagement with the valve seat structure to communicate the condenser outlet with the evaporator when sensed condenser outlet refrigerant temperature is less than the predetermined level and the compressor is off.
  • a vapor compression refrigeration system 10 of the sort used in a household refrigerator or freezer is schematically illustrated in Figure 1.
  • the system 10 is a hermetic circuit containing a refrigerant, preferably R12.
  • the system 10 comprises a compressor 12, a condenser 14, an evaporator 16, an expansion device 18 between the condenser and the evaporator, and a refrigerant flow controlling valve 20 between the condenser and the expansion device 18.
  • the compressor circulates the refrigerant through the system 10 so that heat is transferred from a frozen food compartment 22 to the atmosphere ambient the system as the refrigerant successively evaporates and condenses in the evaporator and condenser.
  • a thermostat (not illustrated) in the compartment 22 cyclically operates the compressor so that the compartment temperature is maintained within desired limits.
  • the compressor 12 compresses gaseous refrigerant flowing from the evaporator and delivers it, at an elevated temperature, to the condenser.
  • the condenser transfers heat from the refrigerant flowing through it to atmospheric air so that the refrigerant condenses in the condenser.
  • Liquified refrigerant flows from the condenser through the expansion device 18 after which it enters the evaporator, having undergone a substantial pressure reduction.
  • the system geometry is such that the liquified refrigerant collects at the discharge end of the condenser before entering the expansion device.
  • the expansion device 18 is preferably formed by a long, small bore capillary tube.
  • the capillary tube design is "loose" in that the tube bore is sufficiently large to pass flows of the liquid refrigerant sufficient to relatively quickly flood the evaporator with liquid refrigerant when the compressor starts up.
  • the refrigerant flow controlling valve 20 varies the refrigerant flow rate from the condenser to the evaporator according to refrigeration system operating parameters to assure efficient operation.
  • the flow controlling valve 20 coacts with the expansion device 18 so that the rate of refrigerant flow into the evaporator varies between zero and the maximum flow permitted by the expansion device acting alone. This coaction enables the refrigeration system to quickly flood the evaporator when the compressor initially operates at the beginning of an "on" cycle (the expansion device being of "loose” design), yet virtually precludes the flow of any substantial amounts of gaseous refrigerant into the evaporator under normal operating conditions.
  • the preferred valve 20, illustrated in figures 2 and 3, is particularly adapted for use in a household freezer.
  • the valve 20 comprises a valve housing 24 defining a refrigerant flow chamber 26 in communication with the refrigerant condenser, a valve seat structure 30 forming a port 32 leading to the expansion device 18, and a refrigerant flow controlling valve assembly 34 coacting with the valve seat structure to control the flow of refrigerant from the refrigerant flow chamber.
  • the valve 20 is constructed primarily of stamped sheet metal parts and is thus of simple, relatively inexpensive construction.
  • the valve housing 24 communicates the condenser 14 to the expansion device 18 and comprises first and second housing members 36, 38 forming the refrigerant flow chamber 26 and refrigerant flow conduits 40, 42, respectively, for directing the refrigerant into and away from the refrigerant flow chamber.
  • the housing members 36, 38 are formed by respective concave confronting cup-like portions 44, 46, having confronting peripheral flanges 50, 52 hermetically secured together about the chamber 26.
  • the conduits 40, 42 are illustrated as comprising refrigerant flow tubes projecting, respectively, to sealed, bonded (preferably brazed) joints (not shown) with the condenser 14 and the expansion device 18.
  • the conduits are also joined to their respective housing members by sealed, bonded joints such as brazed connections.
  • the housing 24 is oriented with the conduit 40 extending upwardly to the condenser and the conduit 42 extending vertically downwardly to the device 18 (see figure 3).
  • the chamber 26 is preferably below the lowest condenser elevation so liquified refrigerant from the condenser flows to the chamber and gaseous refrigerant remains above the liquid refrigerant level. Under most operating conditions the chamber 26 is flooded with the liquified refrigerant.
  • the flow control valve seat structure 30 forms part of the refrigerant flow chamber and in the valve illustrated in Figure 3 comprises a seat support member 60 disposed in the chamber 26 and a valve seat 62 surrounding the refrigerant flow port 32.
  • the illustrated seat support member 60 is formed by a plate having an outer marginal flange 66 hermetically joined between the confronting housing member flanges 50, 52 and a central support section 68 for the seat 62.
  • the central section 68 defines a frustoconical wall 70 adjoining the flange 66, a generally planar annular wall 72 between the wall 70 and the seat 62, and a series of radially extending stiffening ribs 73 embossed in the wall 70.
  • the rib embossments project from the plane of the wall 72 in the direction away from the valving member and in the illustrated valve 20, three ribs are provided extending 120 degrees apart about the port axis.
  • the valve seat 62 projects from the central section 68 and is illustrated in figures 2 and 3 as formed by a central, drawn and pierced projection forming the port 32.
  • the seat region immediately surrounding the port 32 is defined by an annular rim 74 having a sharply radiused projecting edge for contacting the valving structure 34.
  • the rim 74 is quite narrow and the port 32 has a small area.
  • the rim and port areas are slight to make negligible any differential pressure force changes acting on the valving structure when the flow controlling valve 20 is closed or nearly closed.
  • the small rim area also reduces possible effects of localized transient pressure forces caused by high velocity refrigerant flows between the rim and the valving member when the valve is nearly closed.
  • the flow controlling valve assembly 34 governs refrigerant flow through the port 32 in relation to sensed refrigeration system conditions.
  • the valve assembly 34 comprises a valve supporting structure 80 fixed with respect to the housing, an actuator 82, and a valving member 84 connected to the actuator for movement into and away from engagement with the valve seat structure for controlling the flow of refrigerant from the refrigerant flow chamber 26.
  • the valve supporting structure 80 is fixed in the chamber 26 for rigidly positioning and locating the actuator 82 and the valving member 84 with respect to the valve seat structure 30.
  • the valve supporting structure 80 illustrated in figures 2 and 3 comprises a rigid stamped sheet metal plate having an outer peripheral flange section 90, an annular body section 92, and a central, actuator support flange section 94.
  • the flange section 90 is circular and conformed to the size and shape of the housing flanges.
  • the section 90 is sandwiched between the housing flange 50 and the seat structure marginal flange 66 and is hermetically joined to the housing flanges 50, 52 and the marginal flange 66 by a continuous circumferential weld joint 95.
  • the body section 92 extends through the chamber 26 between the flange section 90 and the support flange 94.
  • the body section forms an annular corrugation in the valve support structure.
  • a series of refrigerant flow openings 96 is formed about the body section to permit unrestricted refrigerant flow through the chamber.
  • the corrugated shape of the body section assures that the body section remains structurally strong and stiff regardless of the presence of the openings 96.
  • the actuator support flange 94 is a short, stiff annulus which surrounds a central actuator receiving opening 98.
  • the flange 94 stiffly supports the actuator 82 generally along the center-line of the chamber 26.
  • the actuator 82 is constructed and arranged to shift the valving member 84 between fully opened and fully closed positions and to control the valving member position to modulate flow depending on sensed refrigerant temperature and pressure conditions.
  • the preferred actuator 82 is an expansible chamber pressure actuator having a hermetic expansible operating chamber 100 filled with an operating fluid.
  • the operating fluid is in both its liquid and vapor phases under normal operating conditions so the internal chamber pressure varies with temperature according to the pressure-temperature characteristics of the fill fluid saturated vapor.
  • the fill fluid of the figures 2 and 3 actuator is preferably R 500.
  • the preferred actuator comprises a stiffly resilient metal diaphragm 102 forming a movable wall of the operating chamber 100 and carrying the valving member.
  • the position of the diaphragm 102 relative to the valve seat structure is determined by the refrigerant pressure in the chamber 26, the pressure of the fill fluid in the operating chamber 100 and the internal diaphragm spring force.
  • the actuator 82 is formed by a stiffly resilient single convolution metal bellows comprised of the diaphragm 102, a second diaphragm 104, a fill tube 106, a supporting eyelet 108, and an extension member 110.
  • the diaphragms 102, 104 are stamped from a thin (e.g. 0.006 inch thick) leaf of sinless steel spring material and are initially identical dished discs.
  • diaphragm 104 is constructed to be anchored to the supporting structure 80 by the eyelet 108 which is formed by a malleable metal straight cylindrical sleeve-like body having an annular end flange 111.
  • the eyelet end flange 111 is welded to the centerline of the disc about the opening and the diaphragm is pierced to form a central opening 112 along its centerline.
  • the "bottom” diaphragm 102 carries the valving member 84 on the extension member 110.
  • the extension member illustrated by figures 2 and 3 comprises a flat cylindrical cup-like body stamped from sheet metal.
  • the body has a flat circular base 115, a cylindric wall 116, and projecting fingers 117 disposed about the projecting edge of the wall.
  • the base 115 is welded securely to the diaphragm 102 with the wall 116 and fingers 117 projecting towards the valve seat.
  • the diaphragm discs are aligned in confronting relationship and bonded together about their peripheries by a continuous hermetic weld to provide the operating chamber 100 between them.
  • the partially completed bellows is assembled to the supporting structure 80 with the eyelet 108 extending through the receiving opening 98.
  • the eyelet is upset to form an outwardly extending corrugation 120 which clamps the eyelet firmly to the flange 94.
  • the cylindrical end of the eyelet is swaged at the same time to reduce its diameter to approximate that of the fill tube 106.
  • the fill tube 106 is inserted in the eyelet end and hermetically brazed to the eyelet.
  • the valving member 84 is inserted into the extension cup 110 and the fingers 117 are crimped into engagement with the valving member to secure it in place.
  • the cup wall 116 extends just beyond the valving member toward the valve seat.
  • the preferred valving member 84 is a flat cylindrical disc defining a generally flat valving face confronting the valve seat.
  • the valving face has an area which is quite large compared to the area of the port 32.
  • the preferred and illustrated valving member 84 is composed of a tough, somewhat resilient plastic material, preferably polytetrafluoroethylene (e.g. Teflon) or equivalent, which is resiliently deflected when moved into positive sealing engagement with the valve seat without being cut or abraded by the rim 74.
  • the valving member should be at least some what resilient to assure that the valving member 84 returns substantially to its undeflected condition when the valve is open.
  • the rim of the extension cup wall 116 engages the seat structure wall 72 after the valve fully closes to limit compression of the valving member if the actuator exerts excessive force after closing the valve.
  • the ribs 73 form radially extending channels in the otherwise planar seat structure wall 72. These channels communicate refrigerant at flow chamber pressure to most of the valving member face even when the valve 20 is tightly closed.
  • the small valving member face area occupied by the valve port 32 is insufficient to create a material differential pressure force on the valving member.
  • Teflon or equivalent plastic material is preferred because it does not react with compressor lubricating oil circulating in the system with the refrigerant.
  • Other materials, such as synthetic rubbers or other elastomers, can be used for the valving member so long as they are compatible with the system refrigerant and the compressor lubricant.
  • the bellows is then charged with the fill fluid in such a way that the flow controlling valve is opened at both the high and low ambient temperature operating extremes of the freezer (regardless of the operating condition of the compressor); the flow controlling valve closes when the compressor cycles off during normal operation; and the valve modulates the refrigerant flow in response to predetermined subcooling conditions.
  • a predetermined quantity of fill fluid is introduced to the bellows via the fill tube 106.
  • Charging is carried out under strictly controlled pressure and temperature conditions so that under normal flow controlling valve operating conditions the bellows operates "above” (i.e. at greater than) its free height. That is, the bellows is extended against its own inherent spring force.
  • the differential fluid pressure across the bellows diaphragms is zero the bellows force is relaxed and the bellows "retracts" to its free height.
  • the flow controlling valve is opened in this condition.
  • the fill fluid in the flow controlling valve of figures 2 and 3 (R 500) is selected so that its saturated vapor pressure-temperature characteristic curve has, through the normal operating temperature range, a steeper slope than that of the system refrigerant (in this case R12). See figure 4 where the fill fluid saturated vapor pressure-temperature curve 132 is depicted with the refrigerant saturated vapor pressure-temperature curve 134. When the spring force of the bellows is taken into account, the effective fill fluid pressure-temperature characteristic curve is as illustrated by the line 135 of figure 4.
  • the effective fill fluid pressure is markedly higher than the saturated refrigerant vapor pressure.
  • the bellows extends above its free height and the valve closes if the compressor is not operating. If the compressor operates under these conditions the valve opens and may or may not modulate the refrigerant flow depending on sensed conditions.
  • the fill fluid completely evaporates.
  • the superheated vapor pressure-temperature characteristic curve approximates that of a so-called "perfect" gas (i.e. the slope of the pressure-temperature curve is much less than that of the refrigerant vapor pressure-temperature curve). This is illustrated in Figure 4 at line segment 136.
  • the saturated refrigerant pressure at elevated temperatures rises above the actuator operating chamber pressure and the bellows retracts to fully open the valve 20.
  • the ambient temperature at which the fill fluid evaporates is determined by the quantity of fill fluid introduced into the actuator.
  • the actuator assembly and the valve seat structure are assembled with their flange peripheries aligned and then placed between the housing cups.
  • the assembled elements are fixtured with all the outer flange peripheries aligned and the fill tube 106 extending part way through its associated conduit.
  • the assembly is completed by welding the flanges 50, 52, 66 and, 90 to form the hermetic joint 95 about the flange junctures.
  • Calibration is accomplished by establishing predetermined conditions within the flow controlling valve and distorting the structure of the valve 20 to shift the relative positions of the port 32 and the valving member 84.
  • An example of one calibration technique is to establish a given flow of air through the valve 20 at a predetermined pressure and temperature by yielding the valve seat supporting structure a controlled amount.
  • valves In one series of flow controlling valves it has been found that operationally satisfactory valves are so constructed and arranged that when such a valve is at a temperature of 70°F (21°C) and supplied with air or Nitrogen at that temperature and 78 psig, a flow rate of 0. 15 scfm is established through the valve. To calibrate an uncalibrated valve, the valve is maintained at 70°F and supplied with 70°F Nitrogen or air until a flow rate of 0.15scfm is observed. The gas pressure at this flow rate is less than 78 psig.
  • a calibration ram 140 (schematically illustrated in figure 3) inserted in the conduit 42 is forced against the seat support structure while the flanges 50, 52, 66 and 90 are securely held in place.
  • the "bumping" force applied to the seat yields the support section 68 so that the rim 74 is moved toward the valving member 84. This increases the gas pressure required to achieve a 0.15 scfm flow rate. The process is repeated as necessary until the 78 psig - 0.15 scfm calibration condition has been established.
  • the supporting section 68 is yielded in a generally circular path extending about the radially outer ends of the embossed ribs 73.
  • the ribs are quite stiff and thus dictate where the yielding deflection takes place and thus aid in assuring reliable calibration.
  • valve seat structure can be deformed by introducing high pressure air or Nitrogen into the chamber section between the valve seat structure and the housing cup 46.
  • a gas at about 650 psi, is effective to deform the seat plate for calibration purposes.
  • the port 34 has a sufficiently small area that the deforming gas pressure is easily maintained in the housing without subjecting the actuator 82 to excessive external pressure.
  • the outlet conduit 42 is swaged to reduce the diameter of its outlet and the completed valve 20 is ready for assembly into a freezer unit refrigeration system.
  • the valve 20 is brazed into the refrigeration system and oriented so refrigerant flow through the valve occurs generally vertically downwardly from the condenser through the valve 20 toward the expansion device 18. This valve orientation tends to reduce the possibility of reduced pressure refrigerant remaining in the vicinity of the seat supporting structure after passing through the port 32 and evaporating there. Such evaporation could cause conductive heat transfer from the actuator fill fluid through the extension member 110 and the valving member 84, to the evaporating refrigerant via the valve seat structure.
  • the fill fluid vapor pressure depends on the temperature of the coolest actuator location because that temperature governs condensation of the fill fluid. Conductive heat transfer away from the actuator might thus cause inappropriate actuator response because the actuator would respond to the evaporating refrigerant temperature downstream from the valve port 32 rather than the refrigerant temperature in the flow chamber 26.
  • the refrigeration system After the valve 20 is installed in the freezer the refrigeration system is charged with refrigerant and the system is operated. During normal operation, at relatively high ambient temperatures, the flow controlling valve 20 tends to be open when the compressor is running. In this operating condition the valving member 84 is positioned according to the lowest flow chamber refrigerant temperature detected by the actuator 82. If the refrigeration system is heavily loaded (for example when a large quantity of room temperature meat has just been placed in the freezer) the flow chamber refrigerant temperature is relatively high, signifying that the undesirable passage of hot gas through the expansion device might be imminent. The operating chamber pressure increases as the refrigerant temperature increases so the valving member moves toward the port 32 and restricts the refrigerant flow from the flow chamber 26. This action tends to minimize the possibility of hot gas flowing through the expansion device into the evaporator.
  • the quantity of liquified refrigerant at the condenser discharge end is increased and refrigerant in the flow chamber is subcooled. Accordingly the flow chamber refrigerant temperature is reduced resulting in the valving member retracting from the valve port so the refrigerant flows in a less restricted way from the chamber.
  • the compressor When the food compartment thermostat is satisfied the compressor is cycled “off” and the flow controlling valve 20 closes promptly so that the refrigerant in the condenser remains there at high pressure during the time the compressor is not operating (freezer compartment cooling is not called for).
  • the compressor cycles “off” the pressure in the condenser drops precipitately toward the saturated vapor pressure of the refrigerant in the condenser.
  • the forces acting on the actuator diaphragm promptly come into balance with the actuator stabilizing in its extended position so the flow controlling valve 20 is closed.
  • the forces acting on the diaphragm are the fill fluid vapor pressure force; the bellows spring force; and, the refrigerant vapor pressure force.
  • valve 20 also provides for failsafe operation in that if the actuator operating fluid chamber should leak or be holed for any reason, the fluid pressures acting on the bellows would be balanced and the valve would open due to the diaphragm spring force.
  • the valve 20 opens automatically when the compressor restarts.
  • the thermostat calls for compartment,cooling by turning the compressor "on” and the condenser pressure rises to the compressor discharge level. This creates additional pressure force acting on the actuator bellows in opposition to the fill fluid pressure force. Assuming normal operating conditions, the bellows retracts and the valve 20 opens.
  • Household freezers are sometimes located in unheated spaces (such as garages), or even out-of-doors (for example on open porches), where the atmospheric temperature ambient the freezer may be quite low. In such environments freezers are quite lightly loaded but even so, compressors cycle periodically because compartment temperature set points are below the ambient air temperature and compartment heat gains occur. At low ambient temperatures the system temperature is so low that operation of the compressor may not produce an appreciable condenser pressure rise.
  • the condenser pressure may not be relied on to increase sufficiently to open the flow controlling valve 20. If the valve 20 remains closed the food compartment thermostat can not be satisfied and the compressor continues operating. All the system refrigerant may be delivered into the condenser. Since the compressor lubricating oil is circulated in the system by the refrigerant the compressor can be damaged from insufficient lubrication.
  • the preferred flow controlling valve is biased to its open condition when the ambient temperature is low.
  • the preferred valve 20 thus enables continued system refrigerant flow at low ambient temperatures regardless of the compressor operating condition. This operational feature protects the compressor without materially reducing the refrigeration system operating efficiency because the system is extremely efficient at low ambient temperatures anyway.
  • the flow controlling valve 20 illustrated by Figures 2 and 3 employs an actuator bellows filled with a fluid (R 500) whose saturated vapor pressure-temperature curve is sloped more steeply than the saturated vapor pressure-temperature curve of the system refrigerant (R12). Comparing the curves 134 and 135 of Figure 4 reveals that at low ambient temperatures the system refrigerant vapor pressure force and the diaphragm spring force exceed the actuator operating fluid pressure force. Thus the actuator is biased to open the valve 20.
  • the valving member 84 is moved only a short distance between its full flow and fully closed positions. When the valving member is between these limiting flow positions the refrigerant flow through the port is modulated so that the refrigerant pressure drop between the condenser and the evaporator varies in accordance with the degree of refrigerant subcooling.
  • the preferred single convolution bellows is quite stiff and has a relatively linear spring characteristic through the range of valving member positions between closed and full flow. That is, the actuator spring force opposing extension of the bellows remains substantially constant over the operating range of bellows positions.
  • the flow controlling valve is thus quite sensitive in its response to detected refrigerant pressure and temperature conditions indicative of the degree of its subcooling.
  • valve 20 can be employed in household refrigerators or refrigerator/freezer combinations. Refrigerators and refrigerator/freezers are not designed for use in cold surroundings and therefore do not necessarily require the flow controlling valve to remain open at low ambient temperatures when the compressor is off. Accordingly when so used the valve 20 contains a fill fluid which is the same as the system refrigerant, i.e. R12. The saturated vapor-liquid fill fluid and the bellows coact such that the bellows diaphragm spring force closes the valve 20 when the compressor is off (i.e. the saturated vapor pressure forces within and outside the bellows chamber are balanced). In some refrigerator systems it may also be desirable to form the valving member from a synthetic rubber material rather than "Teflon" so long as the system refrigerant and lubricant do not react to the rubber selected.
  • Figure 5 illustrates part of an alternative refrigerant flow controlling valve construction wherein the valving member blocks refrigerant flow from the condenser when condenser outlet refrigerant temperature is above a predetermined level and the compressor is off, yet is biased to an open position to communicate the condenser outlet with the evaporator when sensed condenser outlet refrigerant temperature is less than the predetermined level and the compressor is off.
  • the Figure 5 valve is constructed primarily from parts which are the same as those described above in reference to Figures 1-3 with corresponding parts indicated by like, primed reference characters.
  • valve 20' of Figure 5 differs from the valve 20 in that when the flow chamber temperature is below the predetermined temperature (e.g. 50F or below) and the compressor is off, the valving member 84' is biased to its open position by a thermally responsive biasing member 150.
  • the actuator fill fluid is the same as that used as the system refrigerant.
  • the biasing member 150 comprises a bimetal element which changes its configuration in response to sensed temperatures below the predetermined level and in so doing engages the valving member 84' to prevent it from closing the port 32'.
  • the illustrated bimetal member is in the form of a two layer disc seated on the seat structure wall 72' with its outer periphery 152 tack welded to the wall 72'.
  • the disc layer confronting the wall 72' has a smaller coefficient of thermal expansion and contraction than that of the layer confronting the valving member 84'.
  • a circular eye 154 is formed at the center of the disc through which the valve seat 156 projects.
  • the valve seat 156 differs from the seat 62 in that the seat 156 projects slightly further from the wall 72' than would the seat 62 in order to accommodate the thickness of the bimetal disc.
  • the actuator 82' is constructed like the actuator 82 except the actuator fill fluid is the same as the system refrigerant (in this case R12).
  • the actuator 82' is filled so that when the internal and external actuator pressures are the same, the actuator diaphragm spring force urges the valving member 84' into engagement with the seat 156 to close the port 32'. This tyically occurs when the compressor is off; but when ambient temperatures are very low the same condition can persist after the compressor has begun to run. This can result in damage to the system as is noted previously.
  • the biasing member 150 prevents the valving member from closing on the seat 156 at low ambient temperatures by buckling into a generally frusto-conical shape with its inner periphery 158 lifting away from the wall 72' and engaging the valving member 84' to block its motion toward the seat. This condition is illustrated by broken lines in Figure 5.
  • the valving member is thus prevented from closing at low temperature when the compressor is off. When temperatures are above the predetermined temperature the bimetal member hugs the wall and does not interfere with operation of the valve 20'.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Temperature-Responsive Valves (AREA)
EP19920104505 1991-03-19 1992-03-16 Refrigeration system subcooling flow control valve Withdrawn EP0504775A3 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US617364 1984-06-05
US61737091A 1991-03-19 1991-03-19
US61736491A 1991-03-19 1991-03-19
US617370 1991-03-19

Publications (2)

Publication Number Publication Date
EP0504775A2 true EP0504775A2 (de) 1992-09-23
EP0504775A3 EP0504775A3 (en) 1993-01-20

Family

ID=27088014

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920104505 Withdrawn EP0504775A3 (en) 1991-03-19 1992-03-16 Refrigeration system subcooling flow control valve

Country Status (2)

Country Link
EP (1) EP0504775A3 (de)
CA (1) CA2063373A1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0805318A2 (de) 1996-05-03 1997-11-05 Electrolux Espana, S.A. Kühlanlage
EP0898131A1 (de) * 1997-08-21 1999-02-24 Fujikoki Corporation Thermostatisches Unterkühlungsventil
EP0931991A3 (de) * 1998-01-21 1999-11-17 Denso Corporation Überkritisches Kühlverfahren

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE275152C (de) * 1912-08-24 1914-06-13 Heizkörper für Zentralheizungen mit durch das abfliessende Heizmittel beeinflusstem Thermostaten
DE950887C (de) * 1954-03-20 1956-10-18 Daimler Benz Ag Thermostatanordnung
US4402455A (en) * 1981-08-28 1983-09-06 Leonard W. Suroff Automatic fluid control assembly
EP0272826A1 (de) * 1986-12-06 1988-06-29 Sanden Corporation Regelgerät für einen Kältekreislauf

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE275152C (de) * 1912-08-24 1914-06-13 Heizkörper für Zentralheizungen mit durch das abfliessende Heizmittel beeinflusstem Thermostaten
DE950887C (de) * 1954-03-20 1956-10-18 Daimler Benz Ag Thermostatanordnung
US4402455A (en) * 1981-08-28 1983-09-06 Leonard W. Suroff Automatic fluid control assembly
EP0272826A1 (de) * 1986-12-06 1988-06-29 Sanden Corporation Regelgerät für einen Kältekreislauf

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0805318A2 (de) 1996-05-03 1997-11-05 Electrolux Espana, S.A. Kühlanlage
US5822999A (en) * 1996-05-03 1998-10-20 Electrolux Espana, S.A. Refrigeration system
EP0898131A1 (de) * 1997-08-21 1999-02-24 Fujikoki Corporation Thermostatisches Unterkühlungsventil
US5996900A (en) * 1997-08-21 1999-12-07 Fujikoki Corporation Thermostatic subcooling control valve
EP0931991A3 (de) * 1998-01-21 1999-11-17 Denso Corporation Überkritisches Kühlverfahren
US6134900A (en) * 1998-01-21 2000-10-24 Denso Corporation Supercritical refrigerating system

Also Published As

Publication number Publication date
CA2063373A1 (en) 1992-09-20
EP0504775A3 (en) 1993-01-20

Similar Documents

Publication Publication Date Title
US3564865A (en) Automotive air-conditioning system
US6189800B1 (en) Expansion valve
EP0892226B1 (de) Drucksteuerventil für Kälteanlage
US3708998A (en) Automatic expansion valve, in line, non-piloted
US6112998A (en) Thermostatic expansion valve having operation reduced with influence of pressure in a refrigerant passage
JP2004270966A (ja) 蒸気圧縮式冷凍機
US5177973A (en) Refrigeration system subcooling flow control valve
KR20080018795A (ko) 팽창 장치
US3998570A (en) Air conditioning compressor
KR100196729B1 (ko) 온도식 팽창 밸브
KR19990080069A (ko) 스텝 모터를 이용한 유량 조절 밸브
US4632305A (en) Expansion valve
US5156017A (en) Refrigeration system subcooling flow control valve
US2215947A (en) Refrigerating apparatus
EP0504775A2 (de) Unterkühlungsstromregelventil für Kälteverfahren
WO2004061378A1 (en) Block valve with integral refrigerant lines
JP3027379B2 (ja) 流量調節弁
US5201190A (en) Refrigerator with subcooling flow control valve
US6484950B2 (en) Expansion valve
JP2007278616A (ja) 膨張装置
US5205131A (en) Refrigerator system with subcooling flow control
US4646533A (en) Refrigerant circuit with improved means to prevent refrigerant flow into evaporator when rotary compressor stops
JP2002071037A (ja) リリーフ弁およびリリーフ弁付き高圧制御弁および超臨界蒸気圧縮冷凍サイクル装置
JP3125824B2 (ja) 過熱防止装置を備えたスクロール圧縮機
US3951569A (en) Air conditioning compressor

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE ES FR GB IT

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE ES FR GB IT

17P Request for examination filed

Effective date: 19930426

17Q First examination report despatched

Effective date: 19940120

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19950607