EP1669703A1 - Expansion valve - Google Patents
Expansion valve Download PDFInfo
- Publication number
- EP1669703A1 EP1669703A1 EP05026630A EP05026630A EP1669703A1 EP 1669703 A1 EP1669703 A1 EP 1669703A1 EP 05026630 A EP05026630 A EP 05026630A EP 05026630 A EP05026630 A EP 05026630A EP 1669703 A1 EP1669703 A1 EP 1669703A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- valve element
- expansion device
- valve
- refrigerant
- piston
- 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- Withdrawn
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Classifications
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- 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
- F25B41/30—Expansion means; Dispositions thereof
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- 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
- F25B2341/00—Details of ejectors not being used as compression device; Details of flow restrictors or expansion valves
- F25B2341/06—Details of flow restrictors or expansion valves
- F25B2341/063—Feed forward expansion valves
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- 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
- F25B2500/00—Problems to be solved
- F25B2500/01—Geometry problems, e.g. for reducing size
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- 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
- F25B2500/00—Problems to be solved
- F25B2500/12—Sound
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- 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
- F25B2600/00—Control issues
- F25B2600/25—Control of valves
- F25B2600/2505—Fixed-differential control valves
Definitions
- the invention relates to an expansion device according to the preamble of claim 1, and particularly for an automotive air conditioner using carbon dioxide (CO 2 ).
- a refrigeration cycle for an automotive air conditioner comprises a receiver for separating condensed refrigerant into gas and liquid, and a thermostatic expansion valve for expanding the liquid refrigerant.
- Other known a refrigeration cycles employ an orifice expansion device for throttling and expanding condensed refrigerant, and an accumulator for separating evaporated refrigerant into gas and liquid.
- the orifice expansion device orifice tube does not control the flow rate.
- the thermostatic expansion valve operates with a variable orifice controlling the flow rate and functions as a differential pressure valve the valve element of which is spring loaded in valve-closing direction. When the differential pressure is small, the valve will close, whereas when the differential pressure exceeds a predetermined value, the valve will open to reduce the differential pressure.
- valve element When the valve element vibrates or oscillates, the flow rate increases, and the vaporization temperature of the refrigerant in the evaporator becomes high, so that the temperature of air which has passed through the evaporator and is blown into a passenger compartment also becomes high.
- the instability of the valve operation can cause hunting of the refrigeration cycle, which makes the temperature of blown-in air unstable.
- a vibration proof spring is mounted on the valve element such that the valve element slides while the vibration proof spring is pressed against an inner housing wall surface.
- the vibration proof spring increases the frictional force at the wall and produces a large hysteresis in the valve flow rate characteristic.
- the valve element may get displaced from a position set as an optimum position, causing degradation of the efficiency of the refrigeration cycle.
- valve element diameter When applied to a refrigeration cycle using CO 2 , the valve element diameter is larger than the port diameter of the valve hole to fully close the valve hole when the differential pressure is small. A lap margin between the valve hole and the valve element thus becomes is large.
- CO 2 passes through the orifice between the valve hole and the valve element, the flow velocity increases and causes a valve element suction phenomenon.
- the valve element tends to move in valve-closing direction and makes the flow rate smaller than a set flow rate, which makes it impossible to obtain sufficient cooling power.
- the damper means With the help of the damper means, it is possible to suppress vibration of the valve element in opening or closing directions, thereby reducing generation of untoward noise, and to prevent that the flow rate increases due to a vibration of the valve element, to thereby suppress an undesirable rise of the temperature of the blown air.
- the damper means also prevents an occurrence of a hunting effect, which makes it possible to stabilise the temperature of the blown-in air.
- the damper means is a measure for preventing generation of untoward noise, and also allows to reduce hysteresis more dramatically than by the known measure utilising increased mechanical sliding resistance, and to thereby obtain stable characteristics and to operate the refrigeration cycle efficiently.
- valve element diameter is selectively set to be close to the port diameter, such that the ratio between the valve element diameter and the port diameter is set not larger than 12.5, with the effect that, surprisingly, valve element suction phenomenon effects can be suppressed.
- the characteristics of the expansion device can be set to some extend by calculation based on only the balance between the pressure received by the valve element and the load of the spring, which greatly facilitates adjustment of the characteristics. Further, due to the suppression of occurrence of the suction phenomenon, it is possible to prevent an accidental reduction of the flow rate of refrigerant, thereby securing the cooling power.
- a refrigeration cycle for an automotive air conditioner using CO 2 as refrigerant comprises in Fig. 1 a compressor 1, a gas cooler 2 for cooling compressed refrigerant, an expansion device 3 for adiabatically expanding the cooled refrigerant, an evaporator 4 for evaporating the adiabatically expanded refrigerant, an accumulator 5 downstream of the evaporator 4 for storing surplus refrigerant, and an internal heat exchanger 6 for cooling the refrigerant cooled by the gas cooler 2, using refrigerant delivered from the accumulator 5 to the compressor 1.
- the expansion device 3 is disposed within a hollow cylindrical body 7.
- the body 7 has an upstream-side end connected to a pipe extending from the internal heat exchanger 6, and an downstream-side end connected to a pipe extending toward the evaporator 4.
- the operation of a refrigeration cycle using CO 2 is substantially the same as when using chlorofluorocarbon.
- the compressor 1 sucks in gaseous-phase refrigerant from the accumulator 5, and discharges after compression the high-temperature, high-pressure refrigerant in a gaseous phase or supercritical state.
- the discharged refrigerant is cooled by the gas cooler 2 and supplied via the internal heat exchanger 6 to the expansion device 3.
- the refrigerant is adiabatically expanded to have the phase state changed from the liquid phase state to a two-phase state of low-temperature, low-pressure gas and liquid.
- the refrigerant in the two-phase gas-liquid state is evaporated by air within a vehicle compartment, to cool the air by depriving the air of latent heat of vaporization.
- the evaporated refrigerant is supplied into the accumulator 5 and is temporarily stored.
- a gaseous-phase portion is returned from the accumulator 5 via the internal heat exchanger 6 to the compressor 1.
- the internal heat exchanger 6 further cools the high-temperature refrigerant cooled in the gas cooler 2, by the low-temperature refrigerant delivered from the accumulator 5 to the compressor 1, or further heats the low-temperature refrigerant from the accumulator 5 to the compressor 1, by the high-temperature refrigerant from the gas cooler 2.
- the expansion device 3 in Fig. 2 has a hollow cylindrical housing 10 with an upper open end forming a primary-side refrigerant inlet port 11, where a strainer 12 is fitted.
- An axially central housing portion is formed with a valve hole 13, the lower peripheral edge of which forms a valve seat 14.
- a valve element 15 is disposed below the valve seat 14.
- the valve element 15 is integral with a coaxial piston 17 axially slidably fitted in a housing cylinder 16.
- the valve element 15 contains a fixed orifice 18 communicating with a horizontal through hole 19 extending through a valve element tip perpendicular to the axis of the housing 10.
- the dimension of the fixed orifice 18 allows a minute amount of refrigerant to pass through when the valve element 15 is seated on the valve seat 14, to enable a circulation of a minimum amount of lubricating oil dissolved in the refrigerant, as required for the lubrication of the compressor 1.
- a secondary-side chamber 20a communicates with a refrigerant outlet port 20 of the housing 10.
- the piston 17 is urged by a spring 21 in valve-closing direction.
- the valve seat 14 and the valve element 15 jointly form a differential pressure valve operated by the balance between the differential pressure between a primary pressure on the upstream side of the valve hole 13 and a secondary pressure on the downstream side plus the load of the spring 21.
- the spring 21 is received by an adjustment screw 22 screwed into the lower end of the housing 10. The load of the spring 21 may be adjusted by adjustment screw 22.
- a space defined by the housing 10, the piston 17, and the adjustment screw 22 forms a damper chamber 23 communicating with the secondary side of the expansion device via a fixed orifice 24 in the adjustment screw 22.
- Refrigerant flows via a clearance between the housing 10 and the piston 17 into the damper chamber 23 and the fixed orifice 24 to the secondary side of the expansion device.
- An O-ring 25 seals between the primary side and the secondary side when the expansion device 3 is inserted into the body 7 shown in Fig. 1.
- the valve element 15 When the differential pressure between the refrigerant inlet port 11 and the refrigerant outlet port 20 is smaller than a predetermined value as determined by the load of the spring 21, the valve element 15 is seated on the valve seat 14 to close the expansion device. Refrigerant flows from the refrigerant outlet port 20 through the fixed orifice 18 at a minimum necessary flow rate.
- valve element 15 When the primary pressure received by the valve element 15 increases, the valve element 15 is moved away from the valve seat 14 to thereby place the expansion device in the open state.
- the primary-side refrigerant flows to the secondary side via a variable orifice defined between the valve seat 14 and the valve element 15.
- the high-temperature, high-pressure gaseous-phase refrigerant is adiabatically expanded into low-temperature, low-pressure refrigerant in a gas-liquid mixture state flowing out from the refrigerant outlet port 20.
- the valve element 15 is lifted to a position where the differential pressure between the primary and secondary pressures and the load of the spring 21 are balanced, and stops at that position.
- the expansion device passes refrigerant at a flow rate corresponding to the differential pressure between the primary and secondary pressures.
- the valve element 15 is able to move without large sliding resistance in accordance with any changes of the primary pressure. When the primary pressure is changing gently, it is possible to reduce hysteresis of the flow rate characteristics.
- valve element 15 When the pressure of the refrigerant inlet port 11 rises sharply, the valve element 15 is urged to move quickly in valve-opening direction. However, the piston 17 tends to move in valve-opening direction to reduce the volume of the damper chamber 23. The pressure within the damper chamber 23 rises and acts to return the piston 17 in valve-closing direction. This restricts a sudden valve-opening motion of the valve element 15 to prevent that the valve element 15 moves in direct accordance with the sharp primary pressure rise. Thereafter, the increased pressure within the damper chamber 23 is progressively released through the clearance between the cylinder 16 and the piston 17 and the fixed orifice 24 such that the force returning the piston 17 in valve-closing direction decreases or is lost.
- valve element 15 and the piston 17 operate opposite to the above case, and for the same reasons, the valve element 15 cannot move in the valve-closing direction in direct accordance with the sharp primary pressure drops.
- the primary pressure sharply rises or drops, sudden motions of the valve element 15 will be suppressed, thereby preventing vibrations of the valve element, and dramatically reducing generation of untoward noises.
- variable orifice is formed by the valve seat 14 of the housing 10 and by the valve element 15.
- the valve element 15 has a diameter "b" larger than a port diameter "a" of the valve hole 13 so that the differential pressure valve can be fully closed, and on the secondary side of the variable orifice, there exists a lap margin of width or the diameters (b - a).
- Fig. 4 in which the abscissa represents the ratio (b/a) of the valve element diameter "b” to the port diameter "a”, and the ordinate represents the suction force, shows that the suction force is small when the ratio (b/a) is low, and as the ratio (b/a) is higher, the suction force is larger. Presumably, this is because when the ratio (b/a) is low, the lap margin is small, and hence the influence of turbulences of the refrigerant flow upon the valve element 15 is small. It is apparent from Fig.
- valve element diameter "b” is selected close to the port diameter "a” to reduce the lap margin, whereby the ratio (b/a) of the valve element diameter "b” to the port diameter "a” is set to about 1.16.
- the expansion device 3 described above operates by a variable orifice having a characteristic such that when the valve is closed, refrigerant flows through the fixed orifice 18 in the valve element 15, and such a characteristic that after the valve is opened, the valve element 15 is progressively lifted according to the differential pressure, i.e. a variable orifice having a single characteristic change point.
- the expansion device 3a in Fig. 5 is provided with a stopper 26 which is screwed into the adjustment screw 22.
- the stopper 26 is axially adjustable in the adjustment screw 22 and serves to restrict the stroke of the piston 17 in valve-opening direction to in turn restrict the maximum lift amount of the valve element 15.
- the maximum lift amount can be determined by adjusting the screw-in amount of the stopper 26 after the load of the spring 21 is adjusted by the adjustment screw 22.
- the stopper 26 has a hollow part which is open to the secondary side. Similar to the refrigerant outlet port 20, the fixed orifice 24 for the damper chamber 23 is formed in an upper end of the stopper 26 opposed to the piston 17.
- the piston 17 and/or the stopper 26 has in the opposed end faces e.g. a groove intersecting the axis of the fixed orifice 24 so as to prevent the fixed orifice 24 from being closed when the piston 17 abuts at the stopper 26.
- the abscissa represents the differential pressure across the valve element 15, and the ordinate represents an opening area formed when the valve element 15 is lifted, which is indicated by an opening diameter as the diameter of a circle having the same area as the opening area.
- the valve element 15 is progressively lifted until the piston 17 abuts at the stopper 26 (e.g. 6MPa in the illustrated example).
- the valve element 15 cannot move any further in valve-opening direction even if the differential pressure further rises, so that the differential pressure valve has a characteristic that the opening diameter does not change further even when the differential pressure rises.
- the change point on the high differential pressure side can be changed by adjusting the stopper 26 accordingly.
- the two change points of the valve-opening characteristic can be adjusted separately by the adjustment screw 22 and the stopper 26. This allows to adjust the two change points for the case where the expansion device 3a is applied to a certain refrigeration cycle, and to tailor the characteristic of the expansion device 3a to a point desirable in terms of system efficiency, so that the degree of freedom in configuring the settings of the characteristic of the expansion device 3a can be enhanced. Further, after the differential pressure has exceeded a predetermined value, the opening diameter no longer increases with a rise in the differential pressure, and hence excessive flow of refrigerant is prevented in an operational region of large differential pressure, which makes it possible to adjust the characteristic of the expansion device 3a to a region ensuring excellent efficiency.
- the stopper 26 instead may be press-fitted into the adjustment screw 22 or member such that the maximum stroke position of the piston 17 in valve-opening direction can be adjusted by the press-fitting depth amount of the stopper 26.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Temperature-Responsive Valves (AREA)
- Air-Conditioning For Vehicles (AREA)
Abstract
Description
- The invention relates to an expansion device according to the preamble of
claim 1, and particularly for an automotive air conditioner using carbon dioxide (CO2). - Generally, a refrigeration cycle for an automotive air conditioner comprises a receiver for separating condensed refrigerant into gas and liquid, and a thermostatic expansion valve for expanding the liquid refrigerant. Other known a refrigeration cycles employ an orifice expansion device for throttling and expanding condensed refrigerant, and an accumulator for separating evaporated refrigerant into gas and liquid. The orifice expansion device orifice tube does not control the flow rate. The thermostatic expansion valve operates with a variable orifice controlling the flow rate and functions as a differential pressure valve the valve element of which is spring loaded in valve-closing direction. When the differential pressure is small, the valve will close, whereas when the differential pressure exceeds a predetermined value, the valve will open to reduce the differential pressure. When the valve element moves in valve-closing direction, the differential pressure rises and tends to move the valve element in valve-opening direction. The differential pressure valve repeatedly performs this operation, and hence the valve element oscillates in opening/closing directions, which can cause untoward noise. Particularly with CO2 as refrigerant, since a very small valve element stroke is controlled by a very large differential pressure, when the pressure rises and falls sharply, it is difficult to immediately stop the valve element at a balanced position. Therefore, the valve element inevitably tends to oscillate thereby generating untoward noise. When the valve element vibrates or oscillates, the flow rate increases, and the vaporization temperature of the refrigerant in the evaporator becomes high, so that the temperature of air which has passed through the evaporator and is blown into a passenger compartment also becomes high. The instability of the valve operation can cause hunting of the refrigeration cycle, which makes the temperature of blown-in air unstable.
- In an expansion device known from JP 2004-218918 A, published August 8, 2004, Fig. 4, a vibration proof spring is mounted on the valve element such that the valve element slides while the vibration proof spring is pressed against an inner housing wall surface. Thus, the motions of the valve element in opening/closing directions is restricted by increased sliding resistance to suppress vibration of the valve element, and to prevent generation of untoward noise. The vibration proof spring increases the frictional force at the wall and produces a large hysteresis in the valve flow rate characteristic. The valve element may get displaced from a position set as an optimum position, causing degradation of the efficiency of the refrigeration cycle. When applied to a refrigeration cycle using CO2, the valve element diameter is larger than the port diameter of the valve hole to fully close the valve hole when the differential pressure is small. A lap margin between the valve hole and the valve element thus becomes is large. When high-pressure CO2 passes through the orifice between the valve hole and the valve element, the flow velocity increases and causes a valve element suction phenomenon. The valve element tends to move in valve-closing direction and makes the flow rate smaller than a set flow rate, which makes it impossible to obtain sufficient cooling power.
- It is an object of the invention to provide an expansion device which both reduces generation of untoward noise and suppresses the occurrence of a valve element suction phenomenon.
- The object is achieved by the features of
claim 1. - With the help of the damper means, it is possible to suppress vibration of the valve element in opening or closing directions, thereby reducing generation of untoward noise, and to prevent that the flow rate increases due to a vibration of the valve element, to thereby suppress an undesirable rise of the temperature of the blown air. The damper means also prevents an occurrence of a hunting effect, which makes it possible to stabilise the temperature of the blown-in air.
As the damper means is a measure for preventing generation of untoward noise, and also allows to reduce hysteresis more dramatically than by the known measure utilising increased mechanical sliding resistance, and to thereby obtain stable characteristics and to operate the refrigeration cycle efficiently. - Moreover, the valve element diameter is selectively set to be close to the port diameter, such that the ratio between the valve element diameter and the port diameter is set not larger than 12.5, with the effect that, surprisingly, valve element suction phenomenon effects can be suppressed. As a result, the characteristics of the expansion device can be set to some extend by calculation based on only the balance between the pressure received by the valve element and the load of the spring, which greatly facilitates adjustment of the characteristics. Further, due to the suppression of occurrence of the suction phenomenon, it is possible to prevent an accidental reduction of the flow rate of refrigerant, thereby securing the cooling power.
- Embodiments of the invention are explained referring to the drawings.
- Fig. 1
- is a schematic view of a refrigeration cycle containing an expansion device,
- Fig. 2
- is a longitudinal section of the expansion device,
- Fig. 3
- is an enlarged section of essential parts of a differential pressure valve,
- Fig. 4
- is a diagram showing changes in the suction force acting on a valve element of the differential pressure valve,
- Fig. 5
- is a longitudinal section of another expansion device, and
- Fig. 6
- is a diagram showing a valve-opening characteristic.
- A refrigeration cycle for an automotive air conditioner using CO2 as refrigerant comprises in Fig. 1 a
compressor 1, agas cooler 2 for cooling compressed refrigerant, anexpansion device 3 for adiabatically expanding the cooled refrigerant, anevaporator 4 for evaporating the adiabatically expanded refrigerant, anaccumulator 5 downstream of theevaporator 4 for storing surplus refrigerant, and aninternal heat exchanger 6 for cooling the refrigerant cooled by thegas cooler 2, using refrigerant delivered from theaccumulator 5 to thecompressor 1. - The
expansion device 3 is disposed within a hollow cylindrical body 7. The body 7 has an upstream-side end connected to a pipe extending from theinternal heat exchanger 6, and an downstream-side end connected to a pipe extending toward theevaporator 4. - The operation of a refrigeration cycle using CO2 is substantially the same as when using chlorofluorocarbon. The
compressor 1 sucks in gaseous-phase refrigerant from theaccumulator 5, and discharges after compression the high-temperature, high-pressure refrigerant in a gaseous phase or supercritical state. The discharged refrigerant is cooled by thegas cooler 2 and supplied via theinternal heat exchanger 6 to theexpansion device 3. In theexpansion device 3, the refrigerant is adiabatically expanded to have the phase state changed from the liquid phase state to a two-phase state of low-temperature, low-pressure gas and liquid. In theevaporator 4, the refrigerant in the two-phase gas-liquid state is evaporated by air within a vehicle compartment, to cool the air by depriving the air of latent heat of vaporization. The evaporated refrigerant is supplied into theaccumulator 5 and is temporarily stored. A gaseous-phase portion is returned from theaccumulator 5 via theinternal heat exchanger 6 to thecompressor 1. In the case of CO2, theinternal heat exchanger 6 further cools the high-temperature refrigerant cooled in thegas cooler 2, by the low-temperature refrigerant delivered from theaccumulator 5 to thecompressor 1, or further heats the low-temperature refrigerant from theaccumulator 5 to thecompressor 1, by the high-temperature refrigerant from thegas cooler 2. - The
expansion device 3 in Fig. 2 has a hollowcylindrical housing 10 with an upper open end forming a primary-siderefrigerant inlet port 11, where astrainer 12 is fitted. An axially central housing portion is formed with avalve hole 13, the lower peripheral edge of which forms avalve seat 14. Avalve element 15 is disposed below thevalve seat 14. Thevalve element 15 is integral with acoaxial piston 17 axially slidably fitted in ahousing cylinder 16. Thevalve element 15 contains afixed orifice 18 communicating with a horizontal throughhole 19 extending through a valve element tip perpendicular to the axis of thehousing 10. The dimension of thefixed orifice 18 allows a minute amount of refrigerant to pass through when thevalve element 15 is seated on thevalve seat 14, to enable a circulation of a minimum amount of lubricating oil dissolved in the refrigerant, as required for the lubrication of thecompressor 1. - A secondary-
side chamber 20a communicates with arefrigerant outlet port 20 of thehousing 10. Thepiston 17 is urged by aspring 21 in valve-closing direction. Thevalve seat 14 and thevalve element 15 jointly form a differential pressure valve operated by the balance between the differential pressure between a primary pressure on the upstream side of thevalve hole 13 and a secondary pressure on the downstream side plus the load of thespring 21. Thespring 21 is received by anadjustment screw 22 screwed into the lower end of thehousing 10. The load of thespring 21 may be adjusted byadjustment screw 22. - A space defined by the
housing 10, thepiston 17, and theadjustment screw 22 forms adamper chamber 23 communicating with the secondary side of the expansion device via afixed orifice 24 in theadjustment screw 22. Refrigerant flows via a clearance between thehousing 10 and thepiston 17 into thedamper chamber 23 and thefixed orifice 24 to the secondary side of the expansion device. An O-ring 25 seals between the primary side and the secondary side when theexpansion device 3 is inserted into the body 7 shown in Fig. 1. - When the differential pressure between the
refrigerant inlet port 11 and therefrigerant outlet port 20 is smaller than a predetermined value as determined by the load of thespring 21, thevalve element 15 is seated on thevalve seat 14 to close the expansion device. Refrigerant flows from therefrigerant outlet port 20 through the fixedorifice 18 at a minimum necessary flow rate. - When the primary pressure received by the
valve element 15 increases, thevalve element 15 is moved away from thevalve seat 14 to thereby place the expansion device in the open state. The primary-side refrigerant flows to the secondary side via a variable orifice defined between thevalve seat 14 and thevalve element 15. The high-temperature, high-pressure gaseous-phase refrigerant is adiabatically expanded into low-temperature, low-pressure refrigerant in a gas-liquid mixture state flowing out from therefrigerant outlet port 20. Thevalve element 15 is lifted to a position where the differential pressure between the primary and secondary pressures and the load of thespring 21 are balanced, and stops at that position. The expansion device passes refrigerant at a flow rate corresponding to the differential pressure between the primary and secondary pressures. Thevalve element 15 is able to move without large sliding resistance in accordance with any changes of the primary pressure. When the primary pressure is changing gently, it is possible to reduce hysteresis of the flow rate characteristics. - When the pressure of the
refrigerant inlet port 11 rises sharply, thevalve element 15 is urged to move quickly in valve-opening direction. However, thepiston 17 tends to move in valve-opening direction to reduce the volume of thedamper chamber 23. The pressure within thedamper chamber 23 rises and acts to return thepiston 17 in valve-closing direction. This restricts a sudden valve-opening motion of thevalve element 15 to prevent that thevalve element 15 moves in direct accordance with the sharp primary pressure rise. Thereafter, the increased pressure within thedamper chamber 23 is progressively released through the clearance between thecylinder 16 and thepiston 17 and the fixedorifice 24 such that the force returning thepiston 17 in valve-closing direction decreases or is lost. When the pressure in therefrigerant inlet port 11 falls sharply, thevalve element 15 and thepiston 17 operate opposite to the above case, and for the same reasons, thevalve element 15 cannot move in the valve-closing direction in direct accordance with the sharp primary pressure drops. Whenever the primary pressure sharply rises or drops, sudden motions of thevalve element 15 will be suppressed, thereby preventing vibrations of the valve element, and dramatically reducing generation of untoward noises. - In the expansion device in Fig. 3 the variable orifice is formed by the
valve seat 14 of thehousing 10 and by thevalve element 15. Thevalve element 15 has a diameter "b" larger than a port diameter "a" of thevalve hole 13 so that the differential pressure valve can be fully closed, and on the secondary side of the variable orifice, there exists a lap margin of width or the diameters (b - a). - When high-pressure CO2 passes through the variable orifice at high speed, turbulences occur on the secondary side tending to cause a suction phenomenon acting on the
valve element 15 such that the valve element is drawn toward thevalve seat 14. The occurrence of the suction phenomenon moves thevalve element 15 in valve-closing direction, and hence when the valve lift is determined depending on the value of the differential pressure, the flow rate becomes lower than the flow rate which would correspond to the value of the differential pressure. - It turned out that the suction phenomenon is largely related to the ratio (b/a) between the valve element diameter "b" and the port diameter "a". Fig. 4, in which the abscissa represents the ratio (b/a) of the valve element diameter "b" to the port diameter "a", and the ordinate represents the suction force, shows that the suction force is small when the ratio (b/a) is low, and as the ratio (b/a) is higher, the suction force is larger. Presumably, this is because when the ratio (b/a) is low, the lap margin is small, and hence the influence of turbulences of the refrigerant flow upon the
valve element 15 is small. It is apparent from Fig. 4 that when the ratio (b/a) of the valve element diameter "b" to the port diameter "a" is not higher than 1.5, the suction force is small, and the effect of the suction phenomenon on thevalve element 15 is slight. In the present preferred embodiment, the valve element diameter "b" is selected close to the port diameter "a" to reduce the lap margin, whereby the ratio (b/a) of the valve element diameter "b" to the port diameter "a" is set to about 1.16. - Since then the effect of the suction phenomenon on the valve element operation is suppressed, i.e. the attraction to the
valve seat 14 due to the flow of refrigerant is weak, it is possible to set the expansion device characteristics to some extent by calculation based on only the balance between the pressure received by thevalve element 15 and the load of thespring 21. Further, since the motion of thevalve element 15 in valve-closing direction due to the suction phenomenon is prevented during operation of the expansion device, it is possible to maintain the refrigerant flow at a predetermined flow rate and to prevent that the cooling power of the refrigeration cycle becomes insufficient. - The
expansion device 3 described above operates by a variable orifice having a characteristic such that when the valve is closed, refrigerant flows through the fixedorifice 18 in thevalve element 15, and such a characteristic that after the valve is opened, thevalve element 15 is progressively lifted according to the differential pressure, i.e. a variable orifice having a single characteristic change point. - Next, an expansion device will be described which has two characteristic change points, i.e. three stages of characteristics. This enhances the degree of freedom in configuring the settings of the expansion device when it is applied to a refrigeration cycle. The
expansion device 3a in Fig. 5 is provided with astopper 26 which is screwed into theadjustment screw 22. Thestopper 26 is axially adjustable in theadjustment screw 22 and serves to restrict the stroke of thepiston 17 in valve-opening direction to in turn restrict the maximum lift amount of thevalve element 15. The maximum lift amount can be determined by adjusting the screw-in amount of thestopper 26 after the load of thespring 21 is adjusted by theadjustment screw 22. - The
stopper 26 has a hollow part which is open to the secondary side. Similar to therefrigerant outlet port 20, the fixedorifice 24 for thedamper chamber 23 is formed in an upper end of thestopper 26 opposed to thepiston 17. Thepiston 17 and/or thestopper 26 has in the opposed end faces e.g. a groove intersecting the axis of the fixedorifice 24 so as to prevent the fixedorifice 24 from being closed when thepiston 17 abuts at thestopper 26. - When the
piston 17 reaches the valve-opening stroke determined by the screw-in position of thestopper 26, a further stroke of thepiston 17 is inhibited. Thus, two change points of the valve-opening characteristic can be set as illustrated in Fig. 6. - In Fig. 6 the abscissa represents the differential pressure across the
valve element 15, and the ordinate represents an opening area formed when thevalve element 15 is lifted, which is indicated by an opening diameter as the diameter of a circle having the same area as the opening area. When the differential pressure is small and the valve is closed, even if the differential pressure changes, a constant opening diameter is maintained by the fixedorifice 18. When the differential pressure has risen to a valve-opening point (e.g. 3MPa in the diagram) determined by the adjusted load of thespring 21 the differential pressure valve starts to open, whereafter the differential pressure valve has a characteristic that the opening diameter changes according to the differential pressure. Then, with a further rise of the differential pressure, thevalve element 15 is progressively lifted until thepiston 17 abuts at the stopper 26 (e.g. 6MPa in the illustrated example). Thevalve element 15 cannot move any further in valve-opening direction even if the differential pressure further rises, so that the differential pressure valve has a characteristic that the opening diameter does not change further even when the differential pressure rises. The change point on the high differential pressure side can be changed by adjusting thestopper 26 accordingly. - In the
expansion device 3a, the two change points of the valve-opening characteristic can be adjusted separately by theadjustment screw 22 and thestopper 26. This allows to adjust the two change points for the case where theexpansion device 3a is applied to a certain refrigeration cycle, and to tailor the characteristic of theexpansion device 3a to a point desirable in terms of system efficiency, so that the degree of freedom in configuring the settings of the characteristic of theexpansion device 3a can be enhanced. Further, after the differential pressure has exceeded a predetermined value, the opening diameter no longer increases with a rise in the differential pressure, and hence excessive flow of refrigerant is prevented in an operational region of large differential pressure, which makes it possible to adjust the characteristic of theexpansion device 3a to a region ensuring excellent efficiency. - The respective adjustment member for adjusting the load of the
spring 21, instead may be constituted by a member press-fitted into the open end of thecylinder 16. In this case, the load of thespring 21 can be adjusted by the press-fitting depth amount. Similarly, thestopper 26 instead may be press-fitted into theadjustment screw 22 or member such that the maximum stroke position of thepiston 17 in valve-opening direction can be adjusted by the press-fitting depth amount of thestopper 26.
Claims (9)
- An expansion device (3, 3a), in particular for a refrigerating cycle of an automatic air conditioner, the expansion device (3, 3a) having a pressure-depending movable valve element (15) in a refrigerant flow path between primary and secondary sides downstream of a valve seat (14) in a state urged in valve-closing direction by a spring (21), the expansion device being capable of passing refrigerant at a flow rate corresponding to a differential pressure between a primary pressure in a refrigerant inlet port (11) and a secondary pressure in a refrigerant outlet port (20), characterised in that damper means (23, 17, 16, 24) are associated to the valve element (15), for accommodating motion of the valve element (15) in opening and/or closing directions when the valve element (15) undergoes a sudden pressure change.
- The expansion device according to claim 1, characterised in that the damper means (23, 17, 16, 24) comprises a cylinder (16) in a housing (10) formed with the valve seat (14), that the cylinder (16) extends coaxially with the valve element opening and/or closing directions, that a piston (17) is slidably disposed in the cylinder (16) and is integrally formed with the valve element (15), and that a damper chamber (23) is provided the volume of which can be changed by the piston (17).
- The expansion device according to claim 2, characterised in that the damper chamber (23) is bounded opposite to the piston (17) by an adjustment member (22) which is screwed or press-fitted into an open end of the cylinder (16), and that the spring (21) is interposed between the piston (17) and the adjustment member (22).
- The expansion device according to claim 3, characterised in that the adjustment member (22) is formed with a fixed orifice (24) for communicating the secondary side of the expansion device (3) with the damper chamber (23).
- The expansion device according to claim 3, characterised by a stopper (26) screwed or press-fitted into the adjustment member (22) such that the stopper (26) is adjustable back and forth along an axis of and in relation to the adjustment member (22), for restricting the stroke of the piston (17) in valve-opening direction.
- The expansion device according to claim 5, characterised in that the stopper (26) contains a fixed orifice (24) communicating the damper chamber (23) and the secondary side of the expansion device (3a).
- The expansion device according to claim 1, characterised in that a ratio (b/a) between a valve element outer diameter (b) and a port diameter (a) of the valve hole (13) is not larger than about 1.5, preferably is about 1.16.
- The expansion device according to claim 2, characterised in that a secondary side chamber (20a) accommodating the valve element (15) communicates with the damper chamber (23) via a clearance provided between the piston (17) and the inner wall of the cylinder (16).
- The expansion device according to claim 1, characterised by the integration of the expansion device (3, 3a) into a refrigeration cycle using carbon dioxide as the refrigerant.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2004354142 | 2004-12-07 | ||
JP2005283622A JP2006189240A (en) | 2004-12-07 | 2005-09-29 | Expansion device |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1669703A1 true EP1669703A1 (en) | 2006-06-14 |
Family
ID=36090802
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP05026630A Withdrawn EP1669703A1 (en) | 2004-12-07 | 2005-12-06 | Expansion valve |
Country Status (4)
Country | Link |
---|---|
US (1) | US20060117793A1 (en) |
EP (1) | EP1669703A1 (en) |
JP (1) | JP2006189240A (en) |
KR (1) | KR20060063730A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2009060465A2 (en) * | 2007-07-18 | 2009-05-14 | Vijay Appa Kasar | Energy saving expansion device for refrigeration & other industries |
EP3712434A1 (en) * | 2019-03-20 | 2020-09-23 | Danfoss A/S | Check valve damping |
Families Citing this family (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5292537B2 (en) * | 2006-08-25 | 2013-09-18 | 株式会社テージーケー | Expansion device |
JP2008138812A (en) * | 2006-12-04 | 2008-06-19 | Tgk Co Ltd | Differential pressure valve |
RU2472078C2 (en) * | 2007-11-13 | 2013-01-10 | Керриер Корпорейшн | Refrigeration systems and method of cold generation |
KR100944763B1 (en) * | 2007-12-17 | 2010-03-03 | 한국기계연구원 | Electronical expansion valve making low noise |
KR101438083B1 (en) | 2008-05-13 | 2014-09-05 | 한라비스테온공조 주식회사 | Cooling system of air conditioner for vehicles |
DE102008033212A1 (en) | 2008-07-15 | 2010-01-21 | Eaton Fluid Power Gmbh | Integration of an ap-expansion valve for optimal COP control in a high-pressure side connection, in particular in an internal heat exchanger |
DE102008052550A1 (en) | 2008-10-21 | 2010-04-22 | Otto Egelhof Gmbh & Co. Kg | Connection device for an internal heat exchanger |
DE102008052549A1 (en) | 2008-10-21 | 2010-04-22 | Otto Egelhof Gmbh & Co. Kg | Connection device for an internal heat exchanger |
JP5440155B2 (en) * | 2009-12-24 | 2014-03-12 | 株式会社デンソー | Decompressor |
US20130180281A1 (en) * | 2010-09-27 | 2013-07-18 | Thermia Varme Ab | Heat exchanger arrangement and heat pump system |
CN102466377B (en) * | 2010-11-18 | 2014-10-29 | 浙江三花股份有限公司 | Expansion valve |
JP6216681B2 (en) * | 2014-04-21 | 2017-10-18 | 株式会社鷺宮製作所 | Aperture device |
JP5971871B2 (en) * | 2014-04-21 | 2016-08-17 | 株式会社鷺宮製作所 | Aperture device |
JP6031078B2 (en) * | 2014-11-12 | 2016-11-24 | 株式会社鷺宮製作所 | Throttle device and refrigeration cycle system including the same |
JP6364381B2 (en) * | 2015-06-23 | 2018-07-25 | 株式会社鷺宮製作所 | Throttle device and refrigeration cycle system including the same |
JP6356644B2 (en) * | 2015-09-04 | 2018-07-11 | 株式会社鷺宮製作所 | Throttle device and refrigeration cycle |
JP6454628B2 (en) * | 2015-10-21 | 2019-01-16 | 株式会社神戸製鋼所 | Intermediate medium gas vaporizer |
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- 2005-09-29 JP JP2005283622A patent/JP2006189240A/en active Pending
- 2005-12-05 US US11/293,278 patent/US20060117793A1/en not_active Abandoned
- 2005-12-06 KR KR1020050117811A patent/KR20060063730A/en not_active Application Discontinuation
- 2005-12-06 EP EP05026630A patent/EP1669703A1/en not_active Withdrawn
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US5117647A (en) * | 1989-07-10 | 1992-06-02 | Danfoss A/S | Servo-controlled expansion valve for a volatile fluid |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2009060465A2 (en) * | 2007-07-18 | 2009-05-14 | Vijay Appa Kasar | Energy saving expansion device for refrigeration & other industries |
WO2009060465A3 (en) * | 2007-07-18 | 2009-08-27 | Vijay Appa Kasar | Energy saving expansion device for refrigeration & other industries |
EP3712434A1 (en) * | 2019-03-20 | 2020-09-23 | Danfoss A/S | Check valve damping |
WO2020187474A1 (en) * | 2019-03-20 | 2020-09-24 | Danfoss A/S | Check valve damping |
Also Published As
Publication number | Publication date |
---|---|
JP2006189240A (en) | 2006-07-20 |
US20060117793A1 (en) | 2006-06-08 |
KR20060063730A (en) | 2006-06-12 |
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