EP1715264A1 - Improved expansion valve for air conditioning circuit - Google Patents

Improved expansion valve for air conditioning circuit Download PDF

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Publication number
EP1715264A1
EP1715264A1 EP05008382A EP05008382A EP1715264A1 EP 1715264 A1 EP1715264 A1 EP 1715264A1 EP 05008382 A EP05008382 A EP 05008382A EP 05008382 A EP05008382 A EP 05008382A EP 1715264 A1 EP1715264 A1 EP 1715264A1
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EP
European Patent Office
Prior art keywords
orifice
expansion device
refrigerant
pressure
expansion
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.)
Granted
Application number
EP05008382A
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German (de)
French (fr)
Other versions
EP1715264B1 (en
Inventor
Mohamed Ben Yahia
Jing Ming Liu
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.)
Valeo Systemes Thermiques SAS
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Valeo Systemes Thermiques SAS
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.)
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Publication date
Application filed by Valeo Systemes Thermiques SAS filed Critical Valeo Systemes Thermiques SAS
Priority to EP05008382A priority Critical patent/EP1715264B1/en
Priority to DE602005021618T priority patent/DE602005021618D1/en
Priority to AT05008382T priority patent/ATE470115T1/en
Priority to ES05008382T priority patent/ES2345497T3/en
Publication of EP1715264A1 publication Critical patent/EP1715264A1/en
Application granted granted Critical
Publication of EP1715264B1 publication Critical patent/EP1715264B1/en
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Anticipated expiration legal-status Critical

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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
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/30—Expansion means; Dispositions thereof
    • F25B41/31—Expansion valves
    • F25B41/33—Expansion valves with the valve member being actuated by the fluid pressure, e.g. by the pressure of the refrigerant
    • 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
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
    • F25B2309/061—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide with cycle highest pressure above the supercritical pressure
    • 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
    • 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
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
    • F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide

Definitions

  • the invention relates to air conditioning circuits, especially for motor vehicles.
  • a conventional air conditioning circuit comprises a compressor, a gas cooler, an expansion device and an evaporator traveled in this order by a refrigerant fluid.
  • the refrigerant is compressed in the gas phase and brought to a high pressure by the compressor. It is then cooled by the air passing through the gas cooler, and then undergoes a loss of pressure passing through the expansion device. The fluid then vaporizes partially.
  • the refrigerant is in the form of a mixture of vapor and low pressure liquid, which is transmitted to the evaporator where it is converted into a gas phase.
  • An internal exchanger may also be provided upstream of the expansion device.
  • the expansion device is a calibrated orifice.
  • Such an expansion device can be easily connected to the rest of the air conditioning circuit, given the simplicity of its structure.
  • the performance of a calibrated orifice for regulating the refrigerant flow rate according to the thermal load conditions are sometimes insufficient and do not allow to have an optimal coefficient of performance.
  • An accumulator is then used at the outlet of the evaporator to prevent an excessively large refrigerant flow from reaching the evaporator and to prevent the compressor from flowing liquid.
  • This accumulator corresponds to a storage area of the non-circulating refrigerant charge. This storage area can increase or decrease depending on the operating conditions. As a result, the accumulator must be particularly bulky, which increases the size of the air conditioning installation.
  • a variable orifice expansion device is used.
  • expansion members are known in which the passage section of the expansion device varies as a function of the high pressure or as a function of the difference between the high pressure and the low pressure.
  • Document JP56-74575 proposes for example an expansion device for an air-conditioning unit traversed by the refrigerant R134a.
  • the expansion device comprises a valve whose degree of opening varies according to the difference between the high pressure and the low pressure. Specifically, the valve opens when the difference between high pressure and low pressure is high and closes when the difference between high pressure and low pressure is low.
  • Such an expansion device has an optimal coefficient of performance which depends on the high pressure and also the low pressure. This results in an expensive and complex structure.
  • Document US Pat. No. 5,018,447 proposes for example an air-conditioning apparatus for a motor vehicle, traversed by a subcritical refrigerant fluid R134a in which the expansion device has a variable orifice.
  • the expansion device comprises a main central opening always open, and at least one peripheral orifice which opens or closes depending on the high pressure of the refrigerant fluid to optimize the cooling of the passenger compartment.
  • the degree of opening of the expansion device depends this time only on the high pressure.
  • such an expansion device is intended to operate with a subcritical refrigerant and is poorly adapted to supercritical refrigerants.
  • the invention improves the situation.
  • the invention also relates to an air conditioning circuit, operating with a fluid refrigerant and comprising a compressor, a gas cooler, an expansion device and an evaporator.
  • the expansion device is as defined according to one of the preceding characteristics.
  • the circuit may further comprise an internal heat exchanger 9, allowing the circulating fluid from the gas cooler to the expansion device to give heat to the fluid flowing from the evaporator to the compressor.
  • the compressor 14 may be an electric or mechanical compressor.
  • the cooling member 11 receives a stream of air to evacuate the heat taken from the refrigerant, which under certain operating conditions is set in motion by a motor-fan unit 15.
  • the air conditioning circuit is traversed by a supercritical refrigerant, for example the refrigerant CO 2 , generally designated by the reference R744.
  • a supercritical refrigerant for example the refrigerant CO 2 , generally designated by the reference R744.
  • FIG. 2A is a sectional view of the expansion device 12 of the invention.
  • the expansion device 12 comprises a body 120, which may be in the general shape of parallelepiped. It can be made for example of aluminum.
  • the body 120 is provided with an inlet compartment 1210 which receives a refrigerant fluid FR at high pressure Hp.
  • This entrance compartment has an entrance 121, intended to be connected to a gas cooler by a connecting pipe 22.
  • the connection between the expansion device and the gas cooler via the connecting pipe 22 may be indirect when other circuit elements, for example the internal heat exchanger 9 are used on the gas cooler / evaporator line.
  • the input 121 may be in the form of a generally horizontal input channel.
  • the "horizontal" direction refers here and in the rest of the description to the general direction flow of the refrigerant fluid in the connection ducts of the circuit.
  • the body 120 further comprises an outlet compartment 1230 which communicates with the inlet compartment 1210.
  • the refrigerant FR which arrives in the outlet compartment 1230 is in a low pressure state LP, following expansion of the refrigerant fluid.
  • the output compartment 1230 has an output 123 intended to be connected to the evaporator 13 through a connecting pipe 23.
  • the refrigerant fluid that arrives in the second outlet compartment 1230 exits the expansion device through the outlet 123.
  • the expansion device 12 comprises a set of expansion means which pass the refrigerant from the inlet compartment 1210 to the outlet compartment 1230, lowering its pressure.
  • the expansion means comprise variable expansion means 1211 and fixed expansion means 35.
  • variable expansion means 1211 comprise a first orifice 34 and a needle 134 which varies the passage section of the first orifice.
  • the fixed expansion means comprise a second orifice 35 having a fixed passage section. The refrigerant can pass from the inlet compartment 1210 to the compartment of outlet 1230, through the orifices 34 and 35.
  • variable expansion means 1211 may be arranged in a housing 1212, for example a lower housing in the form of a tank. They are subjected to the high pressure of the refrigerant coming from the inlet channel 121.
  • the first orifice 34 of the variable expansion means has a variable passage section. Part of the refrigerant of the inlet compartment 1210 can thus be expanded by the first orifice before reaching the outlet compartment 1230.
  • the first orifice 34 may have several degrees of opening.
  • the second orifice 35 of the fixed expansion means has a fixed passage section.
  • a portion of the coolant of the inlet compartment 1210 may also be expanded in the second port prior to arriving in the outlet compartment 1230.
  • the detent means may comprise a closure member 1271 arranged in an auxiliary housing 1272, for example an upper housing in the form of a tank.
  • auxiliary housing 1272 for example an upper housing in the form of a tank.
  • the shutter member is subjected to the high pressure of the coolant from the inlet channel 121.
  • the shutter member comprises a third orifice 37, through which a portion of the coolant of the inlet compartment-1210 can be relaxed before arriving in the outlet compartment 1230.
  • the closure member further comprises a shutter 137 which collaborates with the third orifice 37 to close or to disengage it.
  • the third port 37 can thus be in an open state or in a closed state.
  • the refrigerant CO 2 that arrives in the inlet 121 empties into the compartment input.
  • the inlet compartment 1210 can thus communicate with the outlet compartment 1230 via the variable expansion means 1211, fixed expansion means 35, and the closure member 1271.
  • the first orifice 34 of the variable expansion means and the second orifice 35 of the means for fixed relaxation can be adjacent and disjointed.
  • the needle 134 may vary the passage section of the first port while the second port 35 remains clear.
  • the first orifice 34 of the variable expansion means and the second orifice 35 of the fixed expansion means may be adjacent and together form a common orifice 30.
  • the dashed line embodies the delimitation between the first orifice 34 and the second orifice 35.
  • the needle 134 is adapted to vary the passage section of the first orifice only, while the second orifice 35 remains clear.
  • the needle 134 of the variable expansion means may comprise a control rod 135, substantially perpendicular to the axis of the first orifice 34.
  • the rod is vertical.
  • the following description will be made with reference to a vertical rod, by way of non-limiting example.
  • the rod 135 is fixed by one of these ends to the bottom of the housing. It is further mechanically connected to a partition wall 340, which may be a membrane or a piston. The following description will be made with reference to a piston 340 as a non-limiting example.
  • the vertical movement of the needle 134 is slaved to the high pressure Hp of the refrigerant FR which arrives in the expansion device via the inlet 121, thanks to a spring system 350 arranged in the housing 1212.
  • the needle 134 is then subjected to the force exerted by the high pressure Hp of the refrigerant FR which arrives in the expansion device and the thrust force of the spring 350. These forces are exerted on the piston 340 of the variable expansion means .
  • the needle 134 can move vertically, which varies the passage section of the first orifice 34.
  • the degree of opening of the first orifice 34 depends only on the high pressure Hp and the thrust force of the spring which exerts a counter-force.
  • the needle 134 closes the first orifice 34 to close it and the variable expansion means have no effect on the flow rate of the fluid CO 2 .
  • the needle 134 When the pressure Hp of the coolant is greater than or equal to this first threshold value, the needle 134 begins to open the first orifice 34, so that its passage section begins to increase, thus allowing the passage of a portion of the coolant to the exit compartment 1230.
  • the upward translation of the needle can be limited by a set of stops, including an upper stop 341, when the partition wall 340 is a piston.
  • the piston 340 comes to bear against the abutment 341 when the upper end of the needle 134 reaches the second orifice 35.
  • the stop 341 limits the sliding of the piston 340, which prevents the needle 134 vary the passage section of the second orifice 35.
  • the upper stop 341 is arranged on the side wall of the housing 1212.
  • the upper stop 341 prevents the needle 134 from reducing the passage section of the second orifice 35.
  • the dimensions and the shape of the upper end of the needle 134 are chosen according to the dimensions and the shape of the first orifice 34.
  • the closure member 1271 may be arranged in the upper housing 1272, located downstream of the variable expansion means 1210.
  • the closure member 1271 may be of the discharge valve type. He then understands auxiliary spring system 351 and shutter 137 collaborating with the spring system.
  • the shutter 137 may comprise an auxiliary control rod 138 substantially aligned with the axis of the third orifice 37.
  • the auxiliary rod 138 is vertical.
  • the following description will be made with reference to a vertical auxiliary rod 138, by way of non-limiting example.
  • the rod 138 is fixed by one of these ends to the bottom of the auxiliary housing 1272. It is further mechanically connected to an auxiliary partition wall 370, which may be in particular a piston.
  • the other end of the auxiliary rod is shaped according to the third orifice 37 and has, in particular, a passage section substantially equal to the passage section of the third orifice 37.
  • the piston of the shutter 137 is subjected to the force exerted by the pressure Hp of the fluid FR refrigerant that arrives and the thrust force of the auxiliary spring system 351.
  • the shutter 137 can move vertically. More precisely, when the pressure Hp of the coolant is lower than a second threshold value, the shutter 137 enters the third orifice 37 to close it and the overload valve has no effect on the flow rate of the fluid CO 2 .
  • the shutter 137 rises to open the third orifice 37, and. thus allow the passage of a portion of the refrigerant to the outlet compartment 1230.
  • the overload valve 127 makes it possible to protect the air conditioning circuit when the high pressure Hp of the coolant reaches too high values.
  • the expansion device according to the invention can be modeled by an orifice having a variable equivalent flow section depending on the high pressure of the refrigerant in the inlet compartment.
  • This equivalent passage section corresponds to the accumulation of the respective passage sections of variable expansion means 1211, means of fixed expansion 35, and the closure member 1271.
  • the value of the pressure Hp of the refrigerant fluid that arrives in the expansion device is related to the heat load, and therefore to the cold demand of the user and / or the outside temperature.
  • the expansion device 12 of the invention is designed to control the flow of fluid passing through the orifices 34, 35 and 37 of the expansion means, as a function of the thermal load.
  • FIG. 3 is a diagram showing a model of optimum evolution of the diameter of a variable expansion orifice as a function of the high pressure Hp of the refrigerant fluid.
  • the line ⁇ in this figure corresponds to a modeling of a variable orifice made from measurement points A to F.
  • This figure shows that the cross section of a variable orifice must be a substantially increasing function of the high pressure. Hp so that the coefficient of performance is optimal.
  • FIG. 4 is a diagram showing the evolution of the coefficient of performance COP as a function of the high pressure Hp. It can be seen that a satisfactory coefficient of performance can be obtained for values of the high pressure lying in the neighborhood of 80 bars. If the high pressure is less than about 76 bar, as shown in Part 1 of Figure 4, the coefficient of performance COP is significantly degraded. If the high pressure is substantially greater than 76 bar and substantially less than 84 bar, as shown in Part II of Figure 4, the coefficient of performance COP is much less degraded.
  • the expansion device of the invention is in particular designed to maintain the coefficient of performance in its optimum zone, and thus to bring the high pressure of the refrigerant fluid into an optimum pressure zone substantially between 76 bars and 84 bars.
  • the The minimum diameter of the orifice of an expansion device is generally chosen without taking into account the actual operating conditions, typically around -0.6 mm. This minimum value generates a value of the high pressure Hp that is not optimized with respect to the real operating conditions, which can result in a overconsumption of the engine. This type of expansion device is inadequate at low thermal load.
  • the Applicant has found that by imposing a minimum equivalent passage cross section well adapted to the expansion device, low thermal load, one obtains a high pressure close to this optimum pressure zone and therefore an optimized coefficient of performance.
  • the Applicant has more specifically found that a minimum passage section equivalent of the expansion device S1 substantially between 0.07 mm 2 and 0.16 mm 2 , low thermal load, ensures a high pressure Hp of the refrigerant substantially above 80 bar for most points of the cycle for which the temperature of the refrigerant at the outlet of the gas cooler is of the order of about 30 ° C.
  • Such a minimum passage section S1 may correspond to a minimum equivalent diameter of between 0.3 mm and 0.45 mm.
  • FIG. 5 illustrates the evolution of the equivalent flow section of an expansion device according to the invention, as a function of the values of the high pressure Hp of the refrigerant fluid.
  • the expansion means are shaped so that the minimum equivalent passage section S1 of the expansion device is advantageously between 0.07 mm 2 and 0.16 mm 2 .
  • This minimum equivalent passage section S1 makes it possible to reduce the high pressure of the refrigerant in its optimum zone and in particular in the vicinity of 80 bars.
  • the expansion means are further shaped so that the equivalent passage section of the expansion device goes from the value S1 to a S2 value substantially between 0.45 mm 2 and 0.63 mm 2 , when the high pressure of the refrigerant reaches a value Hp2 substantially equal to 110 bar.
  • the expansion means are shaped so that the equivalent passage section of the expansion device reaches a value S3, substantially between 0.71 mm 2 and 0.95 mm 2 , when the high pressure of the refrigerant reaches a maximum of Hp3 value substantially equal to 135 bars.
  • the expansion means are shaped so that the equivalent passage section of the expansion device remains substantially equal to a value S4, substantially between 2 mm 2 and 6.1 mm 2 when the high pressure of the coolant is substantially greater than or equal to 135 bars.
  • the passage section of the second orifice 35 may be substantially between about 0.07 mm 2 and 0.16 mm 2 .
  • the variable expansion means 1211 are in addition shaped so that the needle 134 closes the first orifice 34, when the high pressure Hp of the coolant is substantially less than 80 bar, and begins to open the first orifice 34, when the high pressure Hp of the refrigerant is of the order of 80 bar.
  • the characteristics of the spring system 350 of the variable expansion means can be chosen so that the needle 134 closes the first orifice 34, when the pressure of the refrigerant which arrives in the inlet compartment is substantially less than 80 bar, and begins to open the first port in the vicinity of 80 bar.
  • variable expansion means 1211 are further shaped so that the passage section of the first orifice 34 varies with the high pressure Hp of the cooling fluid, according to a generally increasing law, when the high pressure Hp of the coolant is substantially between 80.degree. bars and 135 bars.
  • variable expansion means when the high pressure of the refrigerant fluid is substantially greater than or equal to 135 bars, the variable expansion means fully open the first orifice 34.
  • the shutter 137 of the detent member may be shaped to close the third orifice 37, when the pressure Hp of the refrigerant in the compartment of inlet 1210 is substantially less than 135 bar, and to open the third port 37, when the pressure Hp of the coolant in the compartment input 1210 is substantially greater than or equal to 135 bars.
  • the characteristics of the auxiliary spring system 351 of the relief valve may be chosen so that the shutter 137 closes the third orifice 37, when the pressure Hp of the coolant in the inlet compartment is substantially less than 135 bars, and completely releases the third orifice when the high pressure of the coolant is substantially greater than 135 bars.
  • the user's cold demand is low and / or the outside temperature is low.
  • the high pressure Hp of the fluid is then substantially between 0 and 80 bar. Under these conditions, the shutter 137 closes the third orifice 37 and the needle 134 closes the first orifice 34.
  • the expansion is therefore performed by the second orifice 35.
  • the equivalent passage section of the expansion device 12 then corresponds to the passage section of the second orifice 35, and is therefore substantially between 0.07 mm 2 and 0.16 mm 2 . This value makes it possible to reduce the high pressure in its optimal zone, and therefore in the neighborhood of 80 bars.
  • the needle 134 begins to open the first orifice 34 when the high pressure of the coolant is in the vicinity of 80 bar.
  • the high pressure Hp of the fluid is substantially between 80 bars and 135 bars.
  • the shutter 137 still closes the third orifice 37 and the needle 134 has begun to open the first orifice 34.
  • the passage section of the first orifice then begins to evolve according to the high pressure Hp, according to a law generally growing.
  • the expansion is thus still performed by the first orifice 34 and the second orifice 35.
  • the equivalent passage section of the expansion device 12 therefore corresponds to the accumulation of the constant passage section of the second orifice 35 and the variable flow section of the first orifice 34.
  • the equivalent passage section of the expansion device 12 therefore evolves according to the high pressure, according to a generally increasing law.
  • the user's cold demand is high and / or the outside temperature is high.
  • the high pressure Hp of the fluid is then substantially greater than 135 bars.
  • the shutter 137 releases the third orifice and the needle completely opens the first orifice 34.
  • the expansion is thus carried out by the first orifice 34, by the second orifice 35 and by the third orifice 37.
  • the equivalent passage section of the expansion device 12 is then substantially constant and corresponds to the accumulation of the passage section of the second orifice 35. , of the maximum passage section of the first orifice 34, and of the passage section of the third orifice 37.
  • the high pressure is substantially less than the value Hp1, which is substantially equal to 80 bars.
  • the first orifice 34 is closed by the needle 134 and the third orifice 37 is closed by the shutter 137, so that the expansion is performed by the second orifice 35.
  • the equivalent passage section of the expansion device 12 is equal to the passage area of the second orifice 35, and is therefore between 0.07 mm 2 and 0.16 mm 2 , which makes it possible to reduce the high pressure in its zone. optimal and to have a coefficient of performance COP little or no degradation.
  • the high pressure Hp is substantially between the value Hp1, which is of the order of 80 bars, and the value Hp3, which is of the order of 135 bars.
  • the second port 35 is open and the third port 37 is closed.
  • the passage section of the first orifice 34 increases substantially linearly with the high pressure Hp of the refrigerant.
  • the expansion is performed by the first orifice 34 and the second orifice 35.
  • the equivalent passage section of the expansion device therefore evolves substantially linearly with the high pressure Hp.
  • a value S2 substantially between 0.45 mm 2 and 0.63 mm 2 , when the high pressure of the refrigerant is equal to the Hp2 value, which is of the order of 110 bars.
  • the passage section When the high pressure of the refrigerant reaches the value Hp3, which is of the order of 135 bars, the passage section has a value S3, substantially between 0.71 mm 2 and 0.95 mm 2 .
  • the needle 134 fully opens the first orifice 34 while the shutter 137 rises to clear the third orifice 37.
  • the trigger is then performed by the first orifice 34, the second orifice 35, and the third orifice 37.
  • the equivalent passage section of the expansion device then passes to the value S4 which is substantially between 2 mm 2 and 6.1 mm 2 then stay constant.
  • the value S4 may correspond to an equivalent diameter substantially between 1.6 mm and 2.8 mm.
  • the curve of FIG. 6 represents another example of evolution of the passage section equivalent of the expansion device 12 as a function of the high pressure Hp.
  • this curve has an exponential general shape.
  • the curve of FIG. 6 corresponds to a needle shape 134 and to spring stiffnesses different from those used in the expansion device corresponding to FIG. 5. This shape makes it possible to increase the reactivity of the expansion device for very low values. high pressure. Such a curve can be obtained for example by means of a non-linear spring.
  • the equivalent passage section of the of Figure 6 passes through the values S1, S2, S3 when the high pressure of the fluid
  • the refrigerant reaches respectively the values Hp1, Hp2 and Hp3 and remains equal to the value S4 when the high pressure of the refrigerant is substantially greater than or equal to 135 bars.
  • the expansion device according to the invention therefore provides a maximum coefficient of COP performance which depends essentially on the high pressure.
  • the expansion device 12 is shaped so as to have an evolution of the equivalent passage section of the expansion device substantially independent of the low pressure. It is therefore the high pressure that imposes the section equivalent passage of the expansion device and the coefficient of performance. As a result, the structure of the expansion device does not include a return of the low-pressure refrigerant from the outlet compartment 1230 to the inlet compartment 1210. The structure of the expansion device is thus simplified.

Abstract

The device has a body, traversed by a coolant, comprising an inlet compartment (1210), in which the coolant enters, and an outlet compartment (1230), through which the coolant leaves the body. A set of expansion units comprises variable and fixed expansion units. The variable unit has an orifice (34) and a needle (134) varying the passage section of the orifice (34) according to the pressure of the coolant. The fixed unit has an orifice (35) with a fixed passage section. The expansion units allow the coolant to pass from the inlet compartment to the outlet compartment through the orifices.

Description

L'invention concerne les circuits de climatisation, notamment pour véhicules automobiles.The invention relates to air conditioning circuits, especially for motor vehicles.

Un circuit de climatisation classique comporte un compresseur, un refroidisseur de gaz, un dispositif de détente et un évaporateur parcourus, dans cet ordre, par un fluide réfrigérant. Le fluide réfrigérant est comprimé en phase gazeuse et amené à une pression élevée par le compresseur. Il est ensuite refroidi par l'air qui traverse le refroidisseur de gaz, puis subit une perte de pression en passant dans le dispositif de détente. Le fluide se vaporise alors partiellement. A la sortie du dispositif de détente, le fluide réfrigérant est sous la forme d'un mélange de vapeur et de liquide à basse pression, qui est transmis à l'évaporateur où il est transformé en phase gazeuse. Un échangeur interne peut également être prévu en amont du dispositif de détente.A conventional air conditioning circuit comprises a compressor, a gas cooler, an expansion device and an evaporator traveled in this order by a refrigerant fluid. The refrigerant is compressed in the gas phase and brought to a high pressure by the compressor. It is then cooled by the air passing through the gas cooler, and then undergoes a loss of pressure passing through the expansion device. The fluid then vaporizes partially. At the outlet of the expansion device, the refrigerant is in the form of a mixture of vapor and low pressure liquid, which is transmitted to the evaporator where it is converted into a gas phase. An internal exchanger may also be provided upstream of the expansion device.

Dans des réalisations existantes, le dispositif de détente est un orifice calibré. Un tel dispositif de détente peut être aisément raccordé au reste du circuit de climatisation, compte tenu de la simplicité de sa structure. Cependant, les performances d'un orifice calibré pour
réguler le débit de fluide réfrigérant en fonction des conditions de charges thermiques sont parfois insuffisantes et ne permettent pas d'avoir un coefficient de performance optimal. On utilise alors en complément un accumulateur à la sortie de l'évaporateur pour empêcher qu'un débit de fluide frigorigène trop important n'arrive à l'évaporateur et pour éviter les coups de liquide au compresseur. Cet accumulateur correspond à une zone de stockage de la charge non-circulante de fluide réfrigérant. Cette zone de stockage peut augmenter ou diminuer en fonction des conditions de fonctionnement. Par suite, l'accumulateur doit être particuliè-rement volumineux, ce qui augmente l'encombrement de l'installation de climatisation.In existing embodiments, the expansion device is a calibrated orifice. Such an expansion device can be easily connected to the rest of the air conditioning circuit, given the simplicity of its structure. However, the performance of a calibrated orifice for
regulating the refrigerant flow rate according to the thermal load conditions are sometimes insufficient and do not allow to have an optimal coefficient of performance. An accumulator is then used at the outlet of the evaporator to prevent an excessively large refrigerant flow from reaching the evaporator and to prevent the compressor from flowing liquid. This accumulator corresponds to a storage area of the non-circulating refrigerant charge. This storage area can increase or decrease depending on the operating conditions. As a result, the accumulator must be particularly bulky, which increases the size of the air conditioning installation.

Dans d'autres réalisations existantes, on utilise un dispositif de détente à orifice variable. On connaît en particulier, des organes de détente dans lesquels la section de passage du dispositif de détente varie en fonction de la haute pression ou en fonction de la différence entre la.haute pression et la basse pression.In other existing embodiments, a variable orifice expansion device is used. In particular, expansion members are known in which the passage section of the expansion device varies as a function of the high pressure or as a function of the difference between the high pressure and the low pressure.

Le document JP56-74575 propose par exemple un dispositif de détente pour un appareil de climatisation parcouru par le fluide frigorigène R134a. Le dispositif de détente comporte une vanne dont le degré d'ouverture varie en fonction de la différence entre la haute pression et la basse pression. Plus précisément, la vanne s'ouvre lorsque la différence entre la haute pression et la basse pression est élevée et se ferme lorsque la différence entre la haute pression et la basse pression est faible.Document JP56-74575 proposes for example an expansion device for an air-conditioning unit traversed by the refrigerant R134a. The expansion device comprises a valve whose degree of opening varies according to the difference between the high pressure and the low pressure. Specifically, the valve opens when the difference between high pressure and low pressure is high and closes when the difference between high pressure and low pressure is low.

Un tel dispositif de détente a un coefficient de performance optimal qui dépend de la haute pression et également de la basse pression. Il en résulte une structure coûteuse et complexe.Such an expansion device has an optimal coefficient of performance which depends on the high pressure and also the low pressure. This results in an expensive and complex structure.

Le document US 5 081847 propose par exemple un appareil de climatisation pour véhicule automobile, parcouru par un fluide réfrigérant sous-critique R134a dans lequel le dispositif de détente est à orifice variable. Le dispositif de détente comporte un orifice central principal toujours ouvert, et au moins un orifice périphérique qui s'ouvre ou se ferme en fonction de la haute pression du fluide réfrigérant afin d'optimiser le refroidissement de l'habitacle.Document US Pat. No. 5,018,447 proposes for example an air-conditioning apparatus for a motor vehicle, traversed by a subcritical refrigerant fluid R134a in which the expansion device has a variable orifice. The expansion device comprises a main central opening always open, and at least one peripheral orifice which opens or closes depending on the high pressure of the refrigerant fluid to optimize the cooling of the passenger compartment.

Le degré d'ouverture du dispositif de détente ne dépend cette fois que de la haute pression. Cependant, un tel dispositif de détente est prévu pour fonctionner avec un fluide frigorigène sous-critique et est mal adapté aux fluides frigorigènes supercritiques.The degree of opening of the expansion device depends this time only on the high pressure. However, such an expansion device is intended to operate with a subcritical refrigerant and is poorly adapted to supercritical refrigerants.

Or l'utilisation de fluides frigorigènes supercritiques, notamment du fluide frigorigène CO2 (R744), se développe dans les circuits de climatisation des véhicules pour limiter les effets
néfastes des fluides frigorigènes sur l'environnement et il convient donc d'adapter les installations de climatisation à de tels fluides.However, the use of supercritical refrigerants, especially CO 2 refrigerant (R744), is developing in the air conditioning circuits of vehicles to limit the effects
environmental refrigerants and therefore air-conditioning systems need to be adapted to such fluids.

On connaît des dispositifs de détente adaptés pour fonctionner avec le fluide frigorigène CO2. Toutefois, ces dispositifs nécessitent généralement une commande électronique et ont par suite un coût relativement élevé qui les rend mal adaptés aux installations de climatisation automobiles.Known expansion devices adapted to operate with the refrigerant CO 2. However, these devices generally require electronic control and therefore have a relatively high cost that makes them poorly suited to automotive air conditioning systems.

L'invention vient améliorer la situation.The invention improves the situation.

Elle propose à cet effet un dispositif de détente, destiné à être installé dans un circuit de climatisation fonctionnant avec un fluide réfrigérant de type supercritique, et comprenant un corps propre à être traversé par le fluide réfrigérant. Le corps comprend un compartiment d'entrée dans lequel arrive le fluide réfrigérant et un compartiment de sortie par lequel sort le fluide réfrigérant. Le dispositif de détente comporte en outre un ensemble de moyens de détente propres à faire passer le fluide réfrigérant du compartiment d'entrée au compartiment de sortie. Avantageusement, les moyens de détente comprennent:

  • des moyens de détente variable comprenant un premier orifice et un pointeau propre à faire varier la section de passage du premier orifice, et
  • des moyens de détente fixe comprenant un deuxième orifice ayant une section de passage fixe.
It proposes for this purpose an expansion device intended to be installed in an air conditioning circuit operating with a refrigerant fluid of the supercritical type, and comprising a body adapted to be traversed by the refrigerant fluid. The body comprises an inlet compartment in which the cooling fluid arrives and an outlet compartment through which the refrigerant flows. The expansion device further comprises a set of expansion means adapted to pass the refrigerant from the inlet compartment to the outlet compartment. Advantageously, the relaxation means comprise:
  • variable expansion means comprising a first orifice and a needle adapted to vary the passage section of the first orifice, and
  • fixed expansion means comprising a second orifice having a fixed passage section.

Des caractéristiques optionnelles de l'invention, complémentaires ou de substitution, sont
énoncées ci-après:

  • Le premier orifice et le deuxième orifice sont adjacents et disjoints.
  • Le premier orifice et le deuxième orifice sont agencés de manière à former un orifice commun.
  • Les moyens de détente sont conformés de sorte que la section de passage minimale du dispositif de détente soit sensiblement comprise entre 0,07 mm2 et 0, 16 mm2.
  • Les moyens de détente sont agencés de sorte que la section de passage du dispositif de
    détente soit sensiblement comprise entre 0,45 mm2 et 0,63 mm2, lorsque la pression du fluide réfrigérant est sensiblement de l'ordre de 110 bars.
  • Les moyens de détente sont agencés de sorte que la section de passage du dispositif de
    détente soit sensiblement comprise entre 0,71 mm2 et 0,95 mm2, lorsque la pression du fluide réfrigérant est sensiblement de l'ordre de 135 bars.
  • Les moyens de détente sont agencés de sorte que la section de passage du dispositif de
    détente soit sensiblement comprise entre 2 mm2 et 6,1 mm2, lorsque la pression du fluide
    réfrigérant est sensiblement supérieure ou égale à 135 bars.
  • La section de passage du deuxième orifice est sensiblement comprise entre 0,07 mm2 et 0, 16 mm2.
  • Le pointeau est conformé pour fermer le premier orifice lorsque la pression du fluide
    réfrigérant est sensiblement inférieure à 80 bars et pour ouvrir le premier orifice au moins partiellement lorsque la pression du fluide réfrigérant dans le compartiment d'entrée est sensiblement supérieure ou égale à 80 bars.
  • Le pointeau est conformé pour faire varier la section de passage du premier orifice en fonction de la pression du fluide réfrigérant dans le compartiment d'entrée, selon une loi
    généralement croissante, lorsque la pression du fluide réfrigérant dans le compartiment
    d'entrée est sensiblement comprise entre 80 bars et 135 bars.
  • Le pointeau est conformé pour maintenir une ouverture maximale du premier orifice, lorsque la pression du fluide réfrigérant dans le compartiment d'entrée est sensiblement
    supérieure ou égale à 135 bars.
  • Les moyens de détente comprennent en outre un organe d'obturation comprenant un
    troisième orifice et un obturateur propre à obturer ledit troisième orifice.
  • L'obturateur est conformé pour obturer le troisième orifice, lorsque la pression du fluide
    réfrigérant dans le compartiment d'entrée est sensiblement inférieure à 135 bars, et pour ouvrir le troisième orifice, lorsque la pression du fluide réfrigérant dans le compartiment d'entrée est sensiblement supérieure ou égale à 135 bars.
  • Les moyens de détente variable comprennent en outre un système de ressort agencé pour exercer une force sur le pointeau s'opposant à la force exercée par la pression du fluide
    réfrigérant qui arrive dans le compartiment d'entrée.
  • Les moyens de détente variable sont agencés dans un logement du compartiment d'entrée et le pointeau comprend une tige de commande sensiblement-perpendiculaire à l'axe du premier orifice, fixée par une de ces extrémités au fond du logement. La tige est reliée
    mécaniquement à une paroi de séparation sur laquelle s'exercent, d'un côté, la force du
    système de ressort et de l'autre côté, la force due à la pression du fluide réfrigérant arrivant, de sorte que le pointeau est propre à se déplacer en translation, sensiblement perpendiculairement à l'axe de l'orifice.
  • Le fluide réfrigérant est le fluide R744.
Optional features of the invention, complementary or substitution, are
set out below:
  • The first port and the second port are adjacent and disjoint.
  • The first port and the second port are arranged to form a common port.
  • The detent means are shaped so that the minimum passage section the expansion device is substantially between 0.07 mm 2 and 0, 16 mm 2 .
  • The expansion means are arranged so that the passage section of the device of
    expansion is substantially between 0.45 mm 2 and 0.63 mm 2 , when the pressure of the refrigerant is substantially of the order of 110 bar.
  • The expansion means are arranged so that the passage section of the device of
    expansion is substantially between 0.71 mm 2 and 0.95 mm 2 , when the pressure of the refrigerant is substantially of the order of 135 bars.
  • The expansion means are arranged so that the passage section of the device of
    relaxation is substantially between 2 mm 2 and 6.1 mm 2 , when the fluid pressure
    refrigerant is substantially greater than or equal to 135 bars.
  • The passage section of the second orifice is substantially between 0.07 mm 2 and 0.16 mm 2 .
  • The needle is shaped to close the first orifice when the fluid pressure
    refrigerant is substantially less than 80 bar and to open the first port at least partially when the pressure of the refrigerant in the inlet compartment is substantially greater than or equal to 80 bar.
  • The needle is shaped to vary the passage section of the first orifice according to the pressure of the refrigerant in the inlet compartment, according to a law
    generally increasing, when the pressure of the refrigerant in the compartment
    input is substantially between 80 bars and 135 bars.
  • The needle is shaped to maintain a maximum opening of the first orifice, when the pressure of the coolant in the inlet compartment is substantially
    greater than or equal to 135 bars.
  • The detent means further comprise a closure member comprising a
    third orifice and a shutter adapted to close said third orifice.
  • The shutter is shaped to close the third orifice, when the fluid pressure
    refrigerant in the inlet compartment is substantially less than 135 bars, and to open the third port, when the pressure of the refrigerant in the inlet compartment is substantially greater than or equal to 135 bars.
  • The variable expansion means further comprise a spring system arranged to exert a force on the needle opposing the force exerted by the fluid pressure.
    refrigerant that arrives in the entrance compartment.
  • The variable expansion means are arranged in a housing of the inlet compartment and the needle comprises a control rod substantially perpendicular to the axis of the first orifice, fixed by one of these ends to the bottom of the housing. The stem is connected
    mechanically to a partition wall on which, on the one hand, the force of the
    spring system and on the other side, the force due to the pressure of the refrigerating fluid arriving, so that the needle is able to move in translation, substantially perpendicular to the axis of the orifice.
  • The refrigerant is the fluid R744.

L'invention concerne également un circuit de climatisation, fonctionnant avec un fluide
réfrigérant et comprenant un compresseur, un refroidisseur de gaz, un dispositif de détente et un évaporateur. Avantageusement, le dispositif de détente est tel que défini selon l'une des caractéristiques précédentes.The invention also relates to an air conditioning circuit, operating with a fluid
refrigerant and comprising a compressor, a gas cooler, an expansion device and an evaporator. Advantageously, the expansion device is as defined according to one of the preceding characteristics.

D'autres caractéristiques et avantages de l'invention apparaîtront à l'examen de la description détaillée ci-après, et des dessins annexés sur lesquels:

  • la figure 1 est un schéma d'une installation de climatisation fonctionnant selon un cycle supercritique;
  • la figure 2A est une vue en coupe d'un dispositif de détente selon un premier mode de
    réalisation de l'invention;
  • la figure 2B est une vue en coupe d'un dispositif de détente selon un deuxième mode de
    réalisation de l'invention;
  • la figure 3 est un diagramme représentant un modèle d'évolution du diamètre d'un orifice de détente variable en fonction de la haute pression;
  • la figure 4 est un diagramme illustrant l'évolution du coefficient de performance en fonction de la haute pression, dans un circuit de climatisation muni d'un dispositif de détente à orifice variable;
  • la figure 5 est un diagramme représentant un exemple d'évolution de la section de passage d'un dispositif de détente conforme à l'invention en fonction de la haute pression; et
  • la figure 6 est un diagramme représentant un autre exemple d'évolution de la section de passage d'un dispositif de détente conforme à l'invention en fonction de la haute pression.
Other features and advantages of the invention will appear on examining the detailed description below, and the attached drawings in which:
  • Figure 1 is a diagram of an air conditioning system operating in a supercritical cycle;
  • FIG. 2A is a sectional view of an expansion device according to a first embodiment of FIG.
    embodiment of the invention;
  • FIG. 2B is a sectional view of an expansion device according to a second embodiment of FIG.
    embodiment of the invention;
  • FIG. 3 is a diagram representing a model of evolution of the diameter of a variable expansion orifice as a function of the high pressure;
  • FIG. 4 is a diagram illustrating the evolution of the coefficient of performance as a function of the high pressure, in an air conditioning circuit provided with a variable orifice expansion device;
  • Figure 5 is a diagram showing an example of evolution of the passage section of an expansion device according to the invention as a function of the high pressure; and
  • Figure 6 is a diagram showing another example of evolution of the passage section of an expansion device according to the invention as a function of the high pressure.

Les dessins contiennent, pour l'essentiel, des éléments de caractère-certain. Ils pourront donc non seulement servir à mieux faire comprendre la description, mais aussi contribuer à la
définition de l'invention, le cas échéant.The drawings contain, for the most part, elements of certain character. They will be able to not only help to make the description better understood, but also contribute to
definition of the invention, if any.

On se réfère tout d'abord à la figure 1 qui représente un schéma d'un circuit de climatisation 10 destiné à être intégré à un véhicule automobile. Le circuit de climatisation est parcouru par un fluide frigorigène. Le circuit comporte en outre:

  • un compresseur 14 propre à recevoir le fluide à l'état gazeux et à le comprimer,
  • un refroidisseur de gaz 11 propre à refroidir le gaz comprimé par le compresseur,
  • un dispositif de détente 12 propre à abaisser la pression du fluide, et
  • un évaporateur 13 propre à faire passer le fluide provenant du dispositif de détente de l'état liquide à l'état gazeux pour produire un flux d'air climatisé 21, qui peut être envoyé vers l'habitacle du véhicule.
Referring first to Figure 1 which shows a diagram of an air conditioning circuit 10 to be integrated with a motor vehicle. The circuit of air conditioning is covered by a refrigerant. The circuit further comprises:
  • a compressor 14 capable of receiving the fluid in the gaseous state and compressing it,
  • a gas cooler 11 suitable for cooling the compressed gas by the compressor,
  • an expansion device 12 capable of lowering the pressure of the fluid, and
  • an evaporator 13 adapted to pass the fluid from the expansion device from the liquid state to the gaseous state to produce a conditioned air flow 21, which can be sent to the passenger compartment of the vehicle.

Le circuit peut comporter en outre un échangeur thermique interne 9, permettant au fluide circulant du refroidisseur de gaz vers le dispositif de détente de céder de la chaleur au fluide circulant de l'évaporateur vers le compresseur.The circuit may further comprise an internal heat exchanger 9, allowing the circulating fluid from the gas cooler to the expansion device to give heat to the fluid flowing from the evaporator to the compressor.

Le compresseur 14 peut être un compresseur électrique ou mécanique.The compressor 14 may be an electric or mechanical compressor.

L'organe de refroidissement 11 reçoit un flux d'air pour évacuer la chaleur prélevée au fluide frigorigène, qui dans certaines conditions de fonctionnement est mis en mouvement par un groupe moto-ventilateur 15.The cooling member 11 receives a stream of air to evacuate the heat taken from the refrigerant, which under certain operating conditions is set in motion by a motor-fan unit 15.

Le circuit de climatisation est parcouru par un fluide frigorigène supercritique, par exemple le fluide frigorigène CO2, désigné généralement par la référence R744.The air conditioning circuit is traversed by a supercritical refrigerant, for example the refrigerant CO 2 , generally designated by the reference R744.

On se réfère tout d'abord au dispositif de détente de la figure 2A; qui est une vue en coupe du dispositif de détente 12 de l'invention.Reference is first made to the expansion device of FIG. 2A; which is a sectional view of the expansion device 12 of the invention.

Le dispositif de détente 12 comprend un corps 120, qui peut être en forme générale de
parallélépipède. Il peut être réalisé par exemple en aluminium.The expansion device 12 comprises a body 120, which may be in the general shape of
parallelepiped. It can be made for example of aluminum.

Le corps 120 est muni d'un compartiment d'entrée 1210 qui reçoit un fluide réfrigérant FR à haute pression Hp. Ce compartiment d'entrée comporte une entrée 121, destinée à être raccordée à un refroidisseur de gaz par un conduit de raccordement 22. Bien entendu, le raccordement entre le dispositif de détente et le refroidisseur de gaz via le conduit de raccordement 22 peut être indirect lorsque d'autres éléments de circuit, par exemple
l'échangeur thermique interne 9, sont utilisés sur la ligne refroidisseur de gaz/évaporateur.The body 120 is provided with an inlet compartment 1210 which receives a refrigerant fluid FR at high pressure Hp. This entrance compartment has an entrance 121, intended to be connected to a gas cooler by a connecting pipe 22. Of course, the connection between the expansion device and the gas cooler via the connecting pipe 22 may be indirect when other circuit elements, for example
the internal heat exchanger 9 are used on the gas cooler / evaporator line.

L'entrée 121 peut se présenter sous la forme d'un canal d'entrée généralement horizontal. La direction "horizontale" désigne ici et dans la suite de la description la direction générale
d'écoulement du fluide réfrigérant dans les conduits de raccordement du circuit.The input 121 may be in the form of a generally horizontal input channel. The "horizontal" direction refers here and in the rest of the description to the general direction
flow of the refrigerant fluid in the connection ducts of the circuit.

Le corps 120 comprend en outre un compartiment de sortie 1230 qui communique avec le compartiment d'entrée 1210. Le fluide réfrigérant FR qui arrive dans le compartiment de sortie 1230 est dans un état de basse pression BP, suite à une détente du fluide réfrigérant.The body 120 further comprises an outlet compartment 1230 which communicates with the inlet compartment 1210. The refrigerant FR which arrives in the outlet compartment 1230 is in a low pressure state LP, following expansion of the refrigerant fluid.

Le compartiment de sortie 1230 comporte une sortie 123 destinée à être raccordée à
l'évaporateur 13 par un conduit de raccordement 23. Le fluide réfrigérant qui arrive dans le deuxième compartiment de sortie 1230 sort du dispositif de détente par la sortie 123.The output compartment 1230 has an output 123 intended to be connected to
the evaporator 13 through a connecting pipe 23. The refrigerant fluid that arrives in the second outlet compartment 1230 exits the expansion device through the outlet 123.

Le dispositif de détente 12 comporte un ensemble de moyens de détente qui font passer le fluide réfrigérant du compartiment d'entrée 1210 au compartiment de sortie 1230, en abaissant sa pression. Les moyens de détente comprennent des moyens de détente variable 1211 et des moyens de détente fixe 35.The expansion device 12 comprises a set of expansion means which pass the refrigerant from the inlet compartment 1210 to the outlet compartment 1230, lowering its pressure. The expansion means comprise variable expansion means 1211 and fixed expansion means 35.

Les moyens de détente variable 1211 comprennent un premier orifice 34 et un pointeau 134 qui fait varier la section de passage du premier orifice. Les moyens de détente fixe comprennent un deuxième orifice 35 ayant une section de passage fixe. Le fluide réfrigérant peut passer du compartiment d'entrée 1210 au compartiment de sortie 1230, par les orifices 34 et 35.The variable expansion means 1211 comprise a first orifice 34 and a needle 134 which varies the passage section of the first orifice. The fixed expansion means comprise a second orifice 35 having a fixed passage section. The refrigerant can pass from the inlet compartment 1210 to the compartment of outlet 1230, through the orifices 34 and 35.

Les moyens de détente variable 1211 peuvent être agencés dans un logement 1212, par exemple un logement inférieur en forme de cuve. Ils sont soumis à la haute pression du fluide réfrigérant qui arrive du canal d'entrée 121.The variable expansion means 1211 may be arranged in a housing 1212, for example a lower housing in the form of a tank. They are subjected to the high pressure of the refrigerant coming from the inlet channel 121.

Le premier orifice 34 des moyens de détente variable a une section de passage variable. Une partie du fluide réfrigérant du compartiment d'entrée 1210 peut ainsi être détendue par le premier orifice, avant d'arriver dans le compartiment de sortie 1230. Le premier orifice 34
peut avoir plusieurs degrés d'ouverture.The first orifice 34 of the variable expansion means has a variable passage section. Part of the refrigerant of the inlet compartment 1210 can thus be expanded by the first orifice before reaching the outlet compartment 1230. The first orifice 34
may have several degrees of opening.

Le deuxième orifice 35 des moyens de détente fixe a une section de passage fixe. Ainsi, une partie du fluide réfrigérant du compartiment d'entrée 1210 peut également être détendue dans le deuxième orifice, avant.d'arriver dans le compartiment de sortie 1230.The second orifice 35 of the fixed expansion means has a fixed passage section. Thus, a portion of the coolant of the inlet compartment 1210 may also be expanded in the second port prior to arriving in the outlet compartment 1230.

En complément, les moyens de détente peuvent comprendre un organe d'obturation 1271 agencé dans un logement auxiliaire 1272, par exemple un logement supérieur en forme de cuve. La suite de la description sera faite en référence à un dispositif de détente 12 comportant un tel organe d'obturation à titre d'exemple non limitatif.In addition, the detent means may comprise a closure member 1271 arranged in an auxiliary housing 1272, for example an upper housing in the form of a tank. The following description will be made with reference to an expansion device 12 comprising such a closure member by way of non-limiting example.

L'organe d'obturation est soumis à la haute pression du fluide réfrigérant provenant du canal d'entrée 121. L'organe d'obturation comprend un troisième orifice 37 , par lequel une partie- du fluide réfrigérant du compartiment d'entrée-1210-peut être détendue avant d'arriver dans le compartiment de sortie 1230. L'organe d'obturation comporte en outre un obturateur 137 qui collabore avec le troisième orifice 37 pour l'obturer ou pour le dégager. Le troisième orifice 37 peut être ainsi dans un état ouvert ou dans un état fermé.The shutter member is subjected to the high pressure of the coolant from the inlet channel 121. The shutter member comprises a third orifice 37, through which a portion of the coolant of the inlet compartment-1210 can be relaxed before arriving in the outlet compartment 1230. The closure member further comprises a shutter 137 which collaborates with the third orifice 37 to close or to disengage it. The third port 37 can thus be in an open state or in a closed state.

Le fluide réfrigérant CO2 qui arrive dans l'entrée 121 se déverse dans le compartiment d'entrée.The refrigerant CO 2 that arrives in the inlet 121 empties into the compartment input.

Le compartiment d'entrée 1210 peut ainsi communiquer avec le compartiment de sortie 1230 par l'intermédiaire des moyens de détente variable 1211, des moyens de détente fixes 35, et de l'organe d'obturation 1271.The inlet compartment 1210 can thus communicate with the outlet compartment 1230 via the variable expansion means 1211, fixed expansion means 35, and the closure member 1271.

Conformément à un mode de réalisation de l'invention, représenté sur la figure 2A, le premier orifice 34 des moyens de détente variable et le deuxième orifice 35 des moyens de
détente fixe peuvent être adjacents et disjoints. Conformément à ce mode de réalisation, le pointeau 134 peut faire varier la section de passage du premier orifice tandis que le deuxième orifice 35 reste dégagé.According to an embodiment of the invention, shown in FIG. 2A, the first orifice 34 of the variable expansion means and the second orifice 35 of the means for
fixed relaxation can be adjacent and disjointed. In accordance with this embodiment, the needle 134 may vary the passage section of the first port while the second port 35 remains clear.

Dans un autre mode de réalisation de l'invention, représenté sur la figure 2B, le premier orifice 34 des moyens de détente variable et le deuxième orifice 35 des moyens de détente fixe peuvent être adjacents et former ensemble un orifice commun 30. Sur la figure 2B, la ligne en pointillés matérialise la délimitation entre le premier orifice 34 et le deuxième orifice 35. Dans ce mode de réalisation, il n'y a pas de séparation matérielle entre le premier orifice 34 et le deuxième orifice 35, mais seule la partie de l'orifice commun correspondant au premier orifice a une section de passage variable. Pour cela, le pointeau 134 est adapté pour faire varier la section de passage du premier orifice uniquement, tandis que le deuxième orifice 35 reste dégagé.In another embodiment of the invention, shown in FIG. 2B, the first orifice 34 of the variable expansion means and the second orifice 35 of the fixed expansion means may be adjacent and together form a common orifice 30. In FIG. 2B, the dashed line embodies the delimitation between the first orifice 34 and the second orifice 35. In this embodiment, there is no material separation between the first orifice 34 and the second orifice 35, but only the part the common orifice corresponding to the first orifice has a variable passage section. For this, the needle 134 is adapted to vary the passage section of the first orifice only, while the second orifice 35 remains clear.

Le pointeau 134 des moyens de détente variable peut- comprendre -une tige de commande 135, sensiblement perpendiculaire à l'axe du premier orifice 34. Dans les exemples de la figure 2A et 2B, la tige est verticale. La suite de la description sera faite en référence à une tige verticale, à titre d'exemple non limitatif. La tige 135 est fixée par une de ces extrémités au fond du logement. Elle est en outre reliée mécaniquement à une paroi de séparation 340, qui peut être une membrane ou un piston. La suite de la description sera faite en référence à un piston 340 à titre d'exemple non limitatif.The needle 134 of the variable expansion means may comprise a control rod 135, substantially perpendicular to the axis of the first orifice 34. In the examples of FIGS. 2A and 2B, the rod is vertical. The following description will be made with reference to a vertical rod, by way of non-limiting example. The rod 135 is fixed by one of these ends to the bottom of the housing. It is further mechanically connected to a partition wall 340, which may be a membrane or a piston. The following description will be made with reference to a piston 340 as a non-limiting example.

Le mouvement vertical du pointeau 134 est asservi à la haute pression Hp du fluide réfrigérant FR qui arrive dans le dispositif de détente par l'entrée 121, grâce à un système de ressort 350 agencé dans le logement 1212.The vertical movement of the needle 134 is slaved to the high pressure Hp of the refrigerant FR which arrives in the expansion device via the inlet 121, thanks to a spring system 350 arranged in the housing 1212.

Le pointeau 134 est alors soumis à la force exercée par la haute pression Hp du fluide réfrigérant FR qui arrive dans le dispositif de détente et à la force de poussée du ressort 350. Ces forces s'exercent sur le piston 340 des moyens de détente variable.The needle 134 is then subjected to the force exerted by the high pressure Hp of the refrigerant FR which arrives in the expansion device and the thrust force of the spring 350. These forces are exerted on the piston 340 of the variable expansion means .

En fonction des valeurs de ces forces, le pointeau 134 peut se déplacer verticalement, ce qui fait varier la section de passage du premier orifice 34.Depending on the values of these forces, the needle 134 can move vertically, which varies the passage section of the first orifice 34.

Ainsi, le degré d'ouverture du premier orifice 34 ne dépend que de la haute pression Hp et de la force de poussée du ressort qui exerce un contre-effort.Thus, the degree of opening of the first orifice 34 depends only on the high pressure Hp and the thrust force of the spring which exerts a counter-force.

Plus précisément, lorsque la haute pression Hp du fluide réfrigérant est inférieure à une première valeur seuil, le pointeau 134 ferme le premier orifice 34 pour l'obturer et les moyens de détente variable n'ont aucun effet sur le débit du fluide CO2.More precisely, when the high pressure Hp of the coolant is lower than a first threshold value, the needle 134 closes the first orifice 34 to close it and the variable expansion means have no effect on the flow rate of the fluid CO 2 .

Lorsque la pression Hp du fluide réfrigérant est supérieure ou égale à cette première valeur seuil, le pointeau 134 commence à ouvrir le premier orifice 34, de sorte que sa section de passage commence à augmenter, permettant ainsi le passage d'une partie du fluide réfrigérant vers le compartiment de sortie 1230.When the pressure Hp of the coolant is greater than or equal to this first threshold value, the needle 134 begins to open the first orifice 34, so that its passage section begins to increase, thus allowing the passage of a portion of the coolant to the exit compartment 1230.

Dans le mode de réalisation de la figure 2B, la translation du pointeau vers le haut peut être limitée par un ensemble de butées, notamment une butée supérieure 341, lorsque la paroi de séparation 340 est un piston. Le piston 340 vient s'appuyer contre la butée 341 lorsque
l'extrémité supérieure du pointeau 134 atteint le deuxième orifice 35. Ainsi, la butée 341 limite le coulissement du piston 340, ce qui permet d'évite que le pointeau 134 ne fasse varier la section de passage du deuxième orifice 35.In the embodiment of Figure 2B, the upward translation of the needle can be limited by a set of stops, including an upper stop 341, when the partition wall 340 is a piston. The piston 340 comes to bear against the abutment 341 when
the upper end of the needle 134 reaches the second orifice 35. Thus, the stop 341 limits the sliding of the piston 340, which prevents the needle 134 vary the passage section of the second orifice 35.

La butée supérieure 341 est agencée sur la paroi latérale du logement 1212. La butée supérieure 341 empêche que le pointeau 134 ne réduise la section de passage du deuxième orifice 35.The upper stop 341 is arranged on the side wall of the housing 1212. The upper stop 341 prevents the needle 134 from reducing the passage section of the second orifice 35.

Les dimensions et la forme de l'extrémité supérieure du pointeau 134 sont choisie en fonction des dimensions et de la forme du premier orifice 34.The dimensions and the shape of the upper end of the needle 134 are chosen according to the dimensions and the shape of the first orifice 34.

L'organe d'obturation 1271 peut être agencé dans le logement supérieur 1272, placé en aval des moyens de détente variable 1210.The closure member 1271 may be arranged in the upper housing 1272, located downstream of the variable expansion means 1210.

L'organe d'obturation 1271 peut être du type soupape de décharge. Il comprend alors un
système de ressort auxiliaire 351 et l'obturateur 137 collaborant avec le système de ressort.The closure member 1271 may be of the discharge valve type. He then understands
auxiliary spring system 351 and shutter 137 collaborating with the spring system.

L'obturateur 137 peut comprendre une tige auxiliaire de commande 138, sensiblement alignée avec l'axe du troisième orifice 37. Dans les exemples des figures 2A et 2B, la tige auxiliaire 138 est verticale. La suite de la description sera faite en référence à une tige auxiliaire 138 verticale, à titre d'exemple non limitatif. La tige 138 est fixée par une de ces extrémités au fond du logement auxiliaire 1272. Elle est en outre reliée mécaniquement à une paroi de séparation auxiliaire 370, qui peut être notamment un piston.The shutter 137 may comprise an auxiliary control rod 138 substantially aligned with the axis of the third orifice 37. In the examples of FIGS. 2A and 2B, the auxiliary rod 138 is vertical. The following description will be made with reference to a vertical auxiliary rod 138, by way of non-limiting example. The rod 138 is fixed by one of these ends to the bottom of the auxiliary housing 1272. It is further mechanically connected to an auxiliary partition wall 370, which may be in particular a piston.

L'autre extrémité de la tige auxiliaire est conformée en fonction du troisième orifice 37 et a, en particulier, une section de passage sensiblement égale à la section de passage du troisième orifice 37.The other end of the auxiliary rod is shaped according to the third orifice 37 and has, in particular, a passage section substantially equal to the passage section of the third orifice 37.

Le piston de l'obturateur 137 est soumis à la force exercée par la pression Hp du fluide
réfrigérant FR qui arrive et à la force de poussée du système de ressort auxiliaire 351.The piston of the shutter 137 is subjected to the force exerted by the pressure Hp of the fluid
FR refrigerant that arrives and the thrust force of the auxiliary spring system 351.

Ainsi en fonction des valeurs de ces forces, l'obturateur 137 peut se déplacer verticalement. Plus précisément, lorsque la pression Hp du fluide réfrigérant est inférieure à une deuxième valeur seuil, l'obturateur 137 pénètre dans le troisième orifice 37 pour l'obturer et la soupape de surcharge n'a aucun effet sur le débit du fluide CO2.Thus, depending on the values of these forces, the shutter 137 can move vertically. More precisely, when the pressure Hp of the coolant is lower than a second threshold value, the shutter 137 enters the third orifice 37 to close it and the overload valve has no effect on the flow rate of the fluid CO 2 .

Lorsque la pression Hp du fluide réfrigérant est supérieure ou égale à cette deuxième valeur seuil, l'obturateur 137 remonte pour ouvrir le troisième orifice 37, et. permettre ainsi le passage d'une partie du fluide réfrigérant vers le compartiment de sortie 1230.When the pressure Hp of the refrigerant is greater than or equal to this second threshold value, the shutter 137 rises to open the third orifice 37, and. thus allow the passage of a portion of the refrigerant to the outlet compartment 1230.

La soupape de surcharge 127 permet de protéger le circuit de climatisation lorsque la haute pression Hp du fluide réfrigérant atteint des valeurs trop importantes.The overload valve 127 makes it possible to protect the air conditioning circuit when the high pressure Hp of the coolant reaches too high values.

Le dispositif de détente conforme à l'invention peut être modélisé par un orifice ayant une
section de passage équivalente variable en fonction de la haute pression du fluide réfrigérant dans le compartiment d'entrée. Cette section de passage équivalente correspond au cumul des sections de passage respectives de moyens de détente variable 1211, des moyens de
détente fixe 35, et de l'organe d'obturation 1271.The expansion device according to the invention can be modeled by an orifice having a
variable equivalent flow section depending on the high pressure of the refrigerant in the inlet compartment. This equivalent passage section corresponds to the accumulation of the respective passage sections of variable expansion means 1211, means of
fixed expansion 35, and the closure member 1271.

Dans un circuit-de climatisation-automobile, la valeur de la pression Hp du fluide réfrigérant qui arrive dans le dispositif de détente est liée à la charge thermique, et donc à la demande en froid de l'utilisateur et/ou de la température extérieure.In an air conditioning-automobile circuit, the value of the pressure Hp of the refrigerant fluid that arrives in the expansion device is related to the heat load, and therefore to the cold demand of the user and / or the outside temperature. .

Le dispositif de détente 12 de l'invention est conformé pour contrôler le débit de fluide qui passe par les orifices 34, 35 et 37 des moyens de détente, en fonction de la charge thermique.The expansion device 12 of the invention is designed to control the flow of fluid passing through the orifices 34, 35 and 37 of the expansion means, as a function of the thermal load.

La figure 3 est un diagramme représentant un modèle d'évolution optimal du diamètre d'un orifice de détente variable en fonction de la haute pression Hp du fluide réfrigérant. La droite Δ sur cette figure correspond à une modélisation d'un orifice variable réalisée à partir des points de mesure A à F. Cette figure montre que la section de passage d'un orifice variable doit.être une fonction sensiblement croissante de la haute pression Hp pour que le coefficient de performance soit optimal.FIG. 3 is a diagram showing a model of optimum evolution of the diameter of a variable expansion orifice as a function of the high pressure Hp of the refrigerant fluid. The line Δ in this figure corresponds to a modeling of a variable orifice made from measurement points A to F. This figure shows that the cross section of a variable orifice must be a substantially increasing function of the high pressure. Hp so that the coefficient of performance is optimal.

La figure 4 est un diagramme représentant l'évolution du coefficient de performance COP en fonction de la haute pression Hp. On constate qu'un coefficient de performance satisfaisant peut être obtenu pour des valeurs de la haute pression se situant au voisinage de 80 bars. Si la haute pression est inférieure à 76 bars environ, comme représenté sur la partie 1 de la figure 4, le coefficient de performance COP est nettement dégradé. Si la haute pression est sensiblement supérieure à 76 bars et sensiblement inférieure à 84 bars, comme représenté sur la partie II de la figure 4, le coefficient de performance COP est beaucoup moins dégradé. Le dispositif de détente de l'invention est notamment agencé pour maintenir le coefficient de performance dans sa zone optimale, et donc pour ramener la haute pression du fluide réfrigérant dans une zone de pression optimale sensiblement comprise entre 76 bars et 84 bars.FIG. 4 is a diagram showing the evolution of the coefficient of performance COP as a function of the high pressure Hp. It can be seen that a satisfactory coefficient of performance can be obtained for values of the high pressure lying in the neighborhood of 80 bars. If the high pressure is less than about 76 bar, as shown in Part 1 of Figure 4, the coefficient of performance COP is significantly degraded. If the high pressure is substantially greater than 76 bar and substantially less than 84 bar, as shown in Part II of Figure 4, the coefficient of performance COP is much less degraded. The expansion device of the invention is in particular designed to maintain the coefficient of performance in its optimum zone, and thus to bring the high pressure of the refrigerant fluid into an optimum pressure zone substantially between 76 bars and 84 bars.

Dans les installations de climatisation de l'art antérieur, à faible charge thermique, le
diamètre minimal de l'orifice d'un dispositif de détente est généralement choisi sans tenir compte des conditions réelles de fonctionnement, typiquement autour de-0,6 mm. Cette valeur minimale engendre une valeur de la haute pression Hp non optimisée par rapport aux conditions réelles de fonctionnement, ce qui peut avoir comme conséquence une
surconsommation du moteur. Ce type de dispositif de détente est inadéquat à faible charge thermique.In the prior art air-conditioning installations, with a low thermal load, the
The minimum diameter of the orifice of an expansion device is generally chosen without taking into account the actual operating conditions, typically around -0.6 mm. This minimum value generates a value of the high pressure Hp that is not optimized with respect to the real operating conditions, which can result in a
overconsumption of the engine. This type of expansion device is inadequate at low thermal load.

La Demanderesse a trouvé qu'en imposant une section de passage minimale équivalente bien adaptée au dispositif de détente, à faible charge thermique, on obtient une haute pression proche de cette zone de pression optimale et donc un coefficient de performance optimisé. La Demanderesse a plus précisément trouvé qu'une section de passage minimale
équivalente du dispositif de détente S1 sensiblement comprise entre 0,07 mm2 et 0,16 mm2, à faible charge thermique, assure une haute pression Hp du fluide réfrigérant sensiblement
supérieure à 80 bars pour la plupart des points du cycle pour lesquels la température du fluide réfrigérant en sortie du refroidisseur de gaz est de l'ordre de 30°C environ. Une telle section de passage minimale S1 peut correspondre à un diamètre minimal équivalent compris entre 0,3 mm et 0,45 mm.The Applicant has found that by imposing a minimum equivalent passage cross section well adapted to the expansion device, low thermal load, one obtains a high pressure close to this optimum pressure zone and therefore an optimized coefficient of performance. The Applicant has more specifically found that a minimum passage section
equivalent of the expansion device S1 substantially between 0.07 mm 2 and 0.16 mm 2 , low thermal load, ensures a high pressure Hp of the refrigerant substantially
above 80 bar for most points of the cycle for which the temperature of the refrigerant at the outlet of the gas cooler is of the order of about 30 ° C. Such a minimum passage section S1 may correspond to a minimum equivalent diameter of between 0.3 mm and 0.45 mm.

La figure 5 illustre l'évolution de la section de passage équivalente d'un dispositif de détente conforme à l'invention, en fonction des valeurs de la haute pression Hp du fluide réfrigérant. Ainsi, selon un aspect de l'invention, les moyens de détente sont conformés de sorte que la section de passage équivalente minimale S1 du dispositif de détente soit avantageusement comprise entre 0,07 mm2 et 0,16 mm2. Cette section de passage minimale équivalente S1 permet de ramener la haute pression du fluide réfrigérant dans sa zone optimale et notamment au voisinage de 80 bars.FIG. 5 illustrates the evolution of the equivalent flow section of an expansion device according to the invention, as a function of the values of the high pressure Hp of the refrigerant fluid. Thus, according to one aspect of the invention, the expansion means are shaped so that the minimum equivalent passage section S1 of the expansion device is advantageously between 0.07 mm 2 and 0.16 mm 2 . This minimum equivalent passage section S1 makes it possible to reduce the high pressure of the refrigerant in its optimum zone and in particular in the vicinity of 80 bars.

Selon un autre aspect de l'invention, les moyens de détente sont en outre conformés de sorte que la section de passage équivalente du dispositif de détente passe de la valeur S1 à une
valeur S2 sensiblement comprise entre 0,45 mm2 et 0,63 mm2, lorsque la haute pression du fluide réfrigérant atteint une valeur Hp2 sensiblement égale à 110 bars.According to another aspect of the invention, the expansion means are further shaped so that the equivalent passage section of the expansion device goes from the value S1 to a
S2 value substantially between 0.45 mm 2 and 0.63 mm 2 , when the high pressure of the refrigerant reaches a value Hp2 substantially equal to 110 bar.

En complément, les moyens de détente sont conformés de sorte que la section de passage équivalente du dispositif de détente atteigne une valeur S3, sensiblement comprise entre 0,71 mm2 et 0,95 mm2, lorsque la haute pression du fluide réfrigérant atteint une valeur Hp3 sensiblement égale à 135 bars.In addition, the expansion means are shaped so that the equivalent passage section of the expansion device reaches a value S3, substantially between 0.71 mm 2 and 0.95 mm 2 , when the high pressure of the refrigerant reaches a maximum of Hp3 value substantially equal to 135 bars.

En outre, les moyens de détente sont conformés de sorte que la section de passage équivalente du dispositif de détente reste sensiblement égale à une valeur S4, sensiblement comprise entre 2 mm2 et 6,1 mm2 lorsque la haute pression du fluide réfrigérant est sensiblement supérieure ou égale à 135 bars.In addition, the expansion means are shaped so that the equivalent passage section of the expansion device remains substantially equal to a value S4, substantially between 2 mm 2 and 6.1 mm 2 when the high pressure of the coolant is substantially greater than or equal to 135 bars.

Selon un autre aspect de l'invention, la section de passage du deuxième orifice 35 peut être sensiblement comprise entre environ 0,07 mm2 et 0, 16 mm2. Les moyens de détente variable 1211 sont en complément conformés de sorte que le pointeau 134 ferme le premier orifice 34, lorsque la haute pression Hp du fluide réfrigérant est sensiblement inférieure à 80 bars, et commence à ouvrir le premier orifice 34, lorsque la haute pression Hp du fluide réfrigérant est de l'ordre de 80 bars.According to another aspect of the invention, the passage section of the second orifice 35 may be substantially between about 0.07 mm 2 and 0.16 mm 2 . The variable expansion means 1211 are in addition shaped so that the needle 134 closes the first orifice 34, when the high pressure Hp of the coolant is substantially less than 80 bar, and begins to open the first orifice 34, when the high pressure Hp of the refrigerant is of the order of 80 bar.

Pour cela, les caractéristiques du système de ressort 350 des moyens de détente variable peuvent être choisies de sorte que le pointeau 134 ferme le premier orifice 34, lorsque la pression du fluide réfrigérant qui arrive dans le compartiment d'entrée est sensiblement
inférieure à 80 bars, et commence à ouvrir le premier orifice au voisinage de 80 bars.For this, the characteristics of the spring system 350 of the variable expansion means can be chosen so that the needle 134 closes the first orifice 34, when the pressure of the refrigerant which arrives in the inlet compartment is substantially
less than 80 bar, and begins to open the first port in the vicinity of 80 bar.

Les moyens de détente variable 1211 sont en outre conformés de sorte que la section de passage du premier orifice 34 varie avec la haute pression Hp du fluide réfrigérant, selon une loi généralement croissante, lorsque la haute pression Hp du fluide réfrigérant est sensiblement comprise entre 80 bars et 135 bars.The variable expansion means 1211 are further shaped so that the passage section of the first orifice 34 varies with the high pressure Hp of the cooling fluid, according to a generally increasing law, when the high pressure Hp of the coolant is substantially between 80.degree. bars and 135 bars.

Selon un aspect complémentaire de l'invention, lorsque la haute pression du fluide réfrigérant est sensiblement supérieure ou égale à 135 bars, les moyens de détente variable ouvrent entièrement le premier orifice 34.According to a complementary aspect of the invention, when the high pressure of the refrigerant fluid is substantially greater than or equal to 135 bars, the variable expansion means fully open the first orifice 34.

Dans la forme de réalisation où les moyens de détente comprennent un organe d'obturation 1271, l'obturateur 137 de l'organe de détente peut être conformé pour obturer le troisième orifice 37, lorsque la pression Hp du fluide réfrigérant dans le compartiment d'entrée 1210 est sensiblement inférieure à 135 bars, et pour ouvrir le troisième orifice 37, lorsque la pression Hp du fluide réfrigérant dans le compartiment d'entrée 1210 est sensiblement
supérieure ou égale à 135 bars.In the embodiment where the detent means comprise a closure member 1271, the shutter 137 of the detent member may be shaped to close the third orifice 37, when the pressure Hp of the refrigerant in the compartment of inlet 1210 is substantially less than 135 bar, and to open the third port 37, when the pressure Hp of the coolant in the compartment input 1210 is substantially
greater than or equal to 135 bars.

Les caractéristiques du système de ressort auxiliaire 351 de la soupape de décharge peuvent être choisies de sorte que l'obturateur 137 obture le troisième orifice 37, lorsque la pression Hp du fluide réfrigérant dans le compartiment d'entrée est sensiblement inférieure à 135 bars, et dégage entièrement le troisième orifice lorsque la haute pression du fluide réfrigérant est sensiblement supérieure à 135 bars.The characteristics of the auxiliary spring system 351 of the relief valve may be chosen so that the shutter 137 closes the third orifice 37, when the pressure Hp of the coolant in the inlet compartment is substantially less than 135 bars, and completely releases the third orifice when the high pressure of the coolant is substantially greater than 135 bars.

Le fonctionnement du dispositif de détente va maintenant être décrit plus en détail, en
référence à la forme de réalisation avec l'organe d'obturation.The operation of the expansion device will now be described in more detail, in
reference to the embodiment with the closure member.

A faible charge thermique, la demande en froid de l'utilisateur est faible et/ou la température extérieure est faible. La haute pression Hp du fluide est alors sensiblement comprise entre 0 et 80 bars. Dans ces conditions, l'obturateur 137 obture le troisième orifice 37 et le pointeau 134 ferme le premier orifice 34.At low heat load, the user's cold demand is low and / or the outside temperature is low. The high pressure Hp of the fluid is then substantially between 0 and 80 bar. Under these conditions, the shutter 137 closes the third orifice 37 and the needle 134 closes the first orifice 34.

La détente est donc effectuée par le deuxième orifice 35. La section de passage équivalente du dispositif de détente 12 correspond alors à la section de passage du deuxième orifice 35, et est donc sensiblement comprise entre 0,07 mm2 et 0,16 mm2. Cette valeur permet de ramener la haute pression dans sa zone optimale, et donc au voisinage de 80 bars.The expansion is therefore performed by the second orifice 35. The equivalent passage section of the expansion device 12 then corresponds to the passage section of the second orifice 35, and is therefore substantially between 0.07 mm 2 and 0.16 mm 2 . This value makes it possible to reduce the high pressure in its optimal zone, and therefore in the neighborhood of 80 bars.

Le pointeau 134 commence à ouvrir le premier orifice 34 lorsque la haute pression du fluide réfrigérant est au voisinage de 80 bars.The needle 134 begins to open the first orifice 34 when the high pressure of the coolant is in the vicinity of 80 bar.

A plus forte charge thermique, la haute pression Hp du fluide est sensiblement comprise entre 80 bars et 135 bars. L'obturateur 137 obture encore le troisième orifice 37 et le pointeau 134 a commencé à ouvrir le premier orifice 34. La section de passage du premier orifice commence alors à évoluer en fonction de la haute pression Hp, selon une loi
généralement croissante.At higher thermal load, the high pressure Hp of the fluid is substantially between 80 bars and 135 bars. The shutter 137 still closes the third orifice 37 and the needle 134 has begun to open the first orifice 34. The passage section of the first orifice then begins to evolve according to the high pressure Hp, according to a law
generally growing.

La détente est donc encore réalisée par le premier orifice 34 et par le deuxième orifice 35. La section de passage équivalente du dispositif de détente 12 correspond donc au cumul de la section de passage constante du deuxième orifice 35 et de la section de passage variable du premier orifice 34. La section de passage équivalente du dispositif de détente 12 évolue donc en fonction de la haute pression, selon une loi généralement croissante.The expansion is thus still performed by the first orifice 34 and the second orifice 35. The equivalent passage section of the expansion device 12 therefore corresponds to the accumulation of the constant passage section of the second orifice 35 and the variable flow section of the first orifice 34. The equivalent passage section of the expansion device 12 therefore evolves according to the high pressure, according to a generally increasing law.

A forte charge thermique, la demande en froid de l'utilisateur est élevée et/ou la température extérieure est élevée. La haute pression Hp du fluide est alors sensiblement supérieure à 135 bars. Lorsque la haute pression du fluide réfrigérant est au voisinage de 135 bars,
l'obturateur 137 dégage le troisième orifice et le pointeau ouvre entièrement le premier orifice 34.At high heat load, the user's cold demand is high and / or the outside temperature is high. The high pressure Hp of the fluid is then substantially greater than 135 bars. When the high pressure of the coolant is around 135 bars,
the shutter 137 releases the third orifice and the needle completely opens the first orifice 34.

La détente est donc réalisée par le premier orifice 34, par le deuxième orifice 35 et par le troisième orifice 37. La section de passage équivalente du dispositif de détente 12 est alors sensiblement constante et correspond au cumul de la section de passage du deuxième orifice 35, de la section de passage maximale du premier orifice 34, et de la section de passage du troisième orifice 37.The expansion is thus carried out by the first orifice 34, by the second orifice 35 and by the third orifice 37. The equivalent passage section of the expansion device 12 is then substantially constant and corresponds to the accumulation of the passage section of the second orifice 35. , of the maximum passage section of the first orifice 34, and of the passage section of the third orifice 37.

L'évolution de la section de passage équivalente du dispositif de détente 12 en fonction de la
haute pression Hp est représentée par la courbe de la figure 5. Dans l'exemple de la figure 5, cette courbe est constituée de plusieurs segments de droites.The evolution of the equivalent passage section of the expansion device 12 as a function of the
Hp high pressure is represented by the curve of Figure 5. In the example of Figure 5, this curve consists of several segments of straight lines.

Dans la phase à faible charge thermique, la haute pression est sensiblement inférieure à la valeur Hp1, qui est sensiblement égale à 80 bars. Le premier orifice 34 est fermé par le pointeau 134 et le troisième orifice 37 est fermé par l'obturateur 137, de sorte que la détente est réalisée par le deuxième orifice 35.In the low thermal load phase, the high pressure is substantially less than the value Hp1, which is substantially equal to 80 bars. The first orifice 34 is closed by the needle 134 and the third orifice 37 is closed by the shutter 137, so that the expansion is performed by the second orifice 35.

La section de passage équivalente du dispositif de détente 12 est égale à la surface de passage du deuxième orifice 35, et est donc comprise entre 0,07 mm2 et 0,16 mm2, ce qui permet de ramener la haute pression dans sa zone optimale et d'avoir un coefficient de performance COP peu ou pas dégradé.The equivalent passage section of the expansion device 12 is equal to the passage area of the second orifice 35, and is therefore between 0.07 mm 2 and 0.16 mm 2 , which makes it possible to reduce the high pressure in its zone. optimal and to have a coefficient of performance COP little or no degradation.

A partir de la valeur de pression Hpl, de l'ordre de 80 bars, le premier orifice 34 commence à s'ouvrir.From the pressure value Hp1, of the order of 80 bar, the first orifice 34 begins to open.

A plus forte charge thermique, la haute pression Hp est sensiblement comprise entre la valeur Hp1, qui est de l'ordre de 80 bars, et la valeur Hp3, qui est de l'ordre de 135 bars. Le
deuxième orifice 35 est ouvert et le troisième orifice 37 est fermé. Dans l'exemple de la figure 5, la section de passage du premier orifice 34 augmente sensiblement linéairement avec la haute pression Hp du fluide réfrigérant. La détente est réalisée par le premier orifice 34 et par le deuxième orifice 35. La section de passage équivalente du dispositif de détente
évolue donc sensiblement linéairement avec la haute pression Hp.At higher thermal load, the high pressure Hp is substantially between the value Hp1, which is of the order of 80 bars, and the value Hp3, which is of the order of 135 bars. The
second port 35 is open and the third port 37 is closed. In the example of Figure 5, the passage section of the first orifice 34 increases substantially linearly with the high pressure Hp of the refrigerant. The expansion is performed by the first orifice 34 and the second orifice 35. The equivalent passage section of the expansion device
therefore evolves substantially linearly with the high pressure Hp.

Elle atteint en particulier une valeur S2, sensiblement comprise entre 0,45 mm2 et 0,63 mm2, lorsque la haute pression du fluide réfrigérant est égale à la valeur Hp2, qui est de l'ordre de 110 bars.It reaches in particular a value S2, substantially between 0.45 mm 2 and 0.63 mm 2 , when the high pressure of the refrigerant is equal to the Hp2 value, which is of the order of 110 bars.

Lorsque la haute pression du fluide réfrigérant atteint la valeur Hp3, qui est de l'ordre de 135
bars, la section de passage a une valeur S3, sensiblement comprise entre 0,71 mm2 et 0,95 mm2.When the high pressure of the refrigerant reaches the value Hp3, which is of the order of 135
bars, the passage section has a value S3, substantially between 0.71 mm 2 and 0.95 mm 2 .

Par ailleurs, lorsque la haute pression du fluide réfrigérant atteint la valeur Hp3, qui est de l'ordre de 135 bars, le pointeau 134 ouvre entièrement le premier orifice 34 tandis que l'obturateur 137 remonte pour dégager le troisième orifice 37. La détente est alors réalisée par le premier orifice 34, le deuxième orifice 35, et par le troisième orifice 37. La section de passage équivalente du dispositif de détente passe alors à la valeur S4 qui est sensiblement comprise entre 2 mm2 et 6,1 mm2, puis reste constante. La valeur S4 peut correspondre à un diamètre équivalent sensiblement compris entre 1,6 mm et 2,8 mm.Furthermore, when the high pressure of the refrigerant reaches the value Hp3, which is of the order of 135 bar, the needle 134 fully opens the first orifice 34 while the shutter 137 rises to clear the third orifice 37. The trigger is then performed by the first orifice 34, the second orifice 35, and the third orifice 37. The equivalent passage section of the expansion device then passes to the value S4 which is substantially between 2 mm 2 and 6.1 mm 2 then stay constant. The value S4 may correspond to an equivalent diameter substantially between 1.6 mm and 2.8 mm.

La courbe de la figure 6 représente un autre exemple d'évolution de la section de passage
équivalente du dispositif de détente 12 en fonction de la haute pression Hp. Dans l'exemple de la figure 6, cette courbe a une forme générale exponentielle.The curve of FIG. 6 represents another example of evolution of the passage section
equivalent of the expansion device 12 as a function of the high pressure Hp. In the example of Figure 6, this curve has an exponential general shape.

La courbe de la figure 6 correspond à une forme de pointeau 134 et à des raideurs de ressort différentes de celles utilisées dans le dispositif de détente correspondant à la figure 5. Cette forme permet d'augmenter la réactivité du dispositif de détente pour des valeurs très élevées de la haute pression. Une telle courbe peut être obtenue par exemple au moyen d'un ressort non linéaire.The curve of FIG. 6 corresponds to a needle shape 134 and to spring stiffnesses different from those used in the expansion device corresponding to FIG. 5. This shape makes it possible to increase the reactivity of the expansion device for very low values. high pressure. Such a curve can be obtained for example by means of a non-linear spring.

Comme décrit en référence à la figure 5, la section de passage équivalente du dispositif de
détente de la figure 6 passe par les valeurs S1, S2, S3 lorsque la haute pression du fluide
réfrigérant atteint respectivement les valeurs Hp1, Hp2 et Hp3 et reste égale à la valeur S4 lorsque la haute pression du fluide réfrigérant est sensiblement supérieure ou égale à 135 bars.As described with reference to FIG. 5, the equivalent passage section of the
of Figure 6 passes through the values S1, S2, S3 when the high pressure of the fluid
The refrigerant reaches respectively the values Hp1, Hp2 and Hp3 and remains equal to the value S4 when the high pressure of the refrigerant is substantially greater than or equal to 135 bars.

Le dispositif de détente conforme à l'invention permet donc d'obtenir un coefficient de performance COP maximal qui dépend essentiellement de la haute pression.The expansion device according to the invention therefore provides a maximum coefficient of COP performance which depends essentially on the high pressure.

En outre, le dispositif de détente 12 est conformé de manière à avoir une évolution de la section de passage équivalente du dispositif de détente sensiblement indépendante de la basse pression. C'est donc la haute pression qui impose la section de passage équivalente du dispositif de détente et le coefficient de performance. Par suite, la structure du dispositif de détente ne comporte pas de retour du fluide réfrigérant à basse pression du compartiment de sortie 1230 vers le compartiment d'entrée 1210. La structure du dispositif de détente est donc simplifiée.In addition, the expansion device 12 is shaped so as to have an evolution of the equivalent passage section of the expansion device substantially independent of the low pressure. It is therefore the high pressure that imposes the section equivalent passage of the expansion device and the coefficient of performance. As a result, the structure of the expansion device does not include a return of the low-pressure refrigerant from the outlet compartment 1230 to the inlet compartment 1210. The structure of the expansion device is thus simplified.

Bien évidemment, l'invention n'est pas limitée aux modes de réalisation décrits ci-dessus. Elle englobe toutes les variantes de réalisation qui pourront être envisagées par l'homme du métier.Of course, the invention is not limited to the embodiments described above. It encompasses all the embodiments that may be envisaged by those skilled in the art.

Claims (17)

Dispositif de détente, destiné à être installé dans un circuit de climatisation. fonctionnant avec un fluide réfrigérant (FR) de type supercritique, et comprenant un corps (120) propre à être traversé par le fluide réfrigérant, ledit corps comprenant un compartiment d'entrée (1210) dans lequel arrive le fluide réfrigérant et un compartiment de sortie (1230) par lequel sort le fluide réfrigérant, le dispositif de détente comportant en outre un ensemble de moyens de
détente propres à faire passer le fluide réfrigérant du compartiment d'entrée (1210) au compartiment de sortie (1230), caractérisé en ce que les moyens de détente comprennent : - des moyens de détente variable (1212) comprenant un premier orifice (34) et un pointeau (134) propre à faire varier la section de passage du premier orifice (34), et - des moyens de détente fixe comprenant un deuxième orifice (35) ayant une section de passage fixe. Expansion device, intended to be installed in an air conditioning circuit. operating with a refrigerant fluid (FR) of the supercritical type, and comprising a body (120) adapted to be traversed by the cooling fluid, said body comprising an inlet compartment (1210) in which the cooling fluid arrives and an outlet compartment (1230) through which the coolant exits, the expansion device further comprising a set of means for
expansion device adapted to pass the refrigerant fluid from the inlet compartment (1210) to the outlet compartment (1230), characterized in that the expansion means comprise: variable expansion means (1212) comprising a first orifice (34) and a pin (134) adapted to vary the passage section of the first orifice (34), and fixed expansion means comprising a second orifice (35) having a fixed passage section. Dispositif de détente selon la revendication 1, caractérisé en ce que le premier orifice (34) et le deuxième orifice (35) sont adjacents et disjoints.Expansion device according to claim 1, characterized in that the first orifice (34) and the second orifice (35) are adjacent and disjoint. Dispositif de détente selon la revendication 1, caractérisé en ce que le premier orifice (34) et le deuxième orifice (35) sont agencés de manière à former un orifice commun.An expansion device according to claim 1, characterized in that the first port (34) and the second port (35) are arranged to form a common port. Dispositif de détente selon l'une des revendications 1 à 3, caractérisé en ce que les moyens de détente sont conformés de sorte que la section de passage minimale du dispositif de détente (12) soit sensiblement comprise entre 0,07 mm2 et 0, 16 mm2.Expansion device according to one of claims 1 to 3, characterized in that the expansion means are shaped so that the minimum passage section of the expansion device (12) is substantially between 0.07 mm 2 and 0, 16 mm 2 . Dispositif de détente selon l'une des revendications 1 à 4, caractérisé en ce que les moyens de détente sont agencés de sorte que la section de passage du dispositif de détente soit sensiblement comprise entre 0,45 mm2 et 0,63 mm2, lorsque la pression du fluide
réfrigérant est sensiblement de l'ordre de 110 bars.Expansion device according to one of claims 1 to 4, characterized in that the expansion means are arranged so that the passage section of the expansion device is substantially between 0.45 mm 2 and 0.63 mm 2 , when the fluid pressure
refrigerant is substantially of the order of 110 bars. Dispositif de détente selon l'une des revendications 1 à 5, caractérisé en ce que les moyens de détente sont agencés de sorte que la section de passage du dispositif de détente soit sensiblement comprise entre 0,71 mm2 et 0,95 mm2, lorsque la pression du fluide
réfrigérant est sensiblement de l'ordre de 135 bars.Expansion device according to one of claims 1 to 5, characterized in that the expansion means are arranged so that the passage section of the expansion device is substantially between 0.71 mm 2 and 0.95 mm 2 , when fluid pressure
refrigerant is substantially of the order of 135 bars. Dispositif de détente selon la revendication 1 à 6, caractérisé en ce que les moyens de
détente sont agencés de sorte que la section de passage du dispositif de détente soit sensiblement comprise entre 2 mm2 et 6,1 mm2, lorsque la pression du fluide réfrigérant est sensiblement supérieure ou égale à 135 bars.Expansion device according to one of claims 1 to 6, characterized in that the means for
are arranged so that the passage section of the expansion device is substantially between 2 mm 2 and 6.1 mm 2 , when the pressure of the refrigerant is substantially greater than or equal to 135 bar. Dispositif de détente selon l'une des revendications précédentes, caractérisé en ce que la section de passage du deuxième orifice (35) est sensiblement comprise entre 0,07 mm2 et 0, 16 mm2.Expansion device according to one of the preceding claims, characterized in that the passage section of the second orifice (35) is substantially between 0.07 mm 2 and 0, 16 mm 2 . Dispositif de détente selon l'une des revendications précédentes, caractérisé en ce que le pointeau (134) est conformé pour fermer le premier orifice (34) lorsque la pression du fluide réfrigérant est sensiblement inférieure à 80 bars et pour ouvrir le premier orifice (34) au moins partiellement lorsque la pression du fluide réfrigérant dans le compartiment d'entrée (1210) est sensiblement supérieure ou égale à 80 bars.Expansion device according to one of the preceding claims, characterized in that the needle (134) is shaped to close the first orifice (34) when the pressure of the coolant is substantially less than 80 bar and to open the first orifice (34). ) at least partially when the pressure of the refrigerant in the inlet compartment (1210) is substantially greater than or equal to 80 bar. Dispositif de détente selon la revendication 9, caractérisé en ce que le pointeau (134) est conformé pour faire varier la section de passage du premier orifice (34) en fonction de la pression du fluide réfrigérant dans le compartiment d'entrée (1210), selon une loi
généralement croissante, lorsque la pression du fluide réfrigérant dans le compartiment
d'entrée (1210) est sensiblement comprise entre 80 bars et 135 bars.Expansion device according to claim 9, characterized in that the needle (134) is shaped to vary the passage section of the first orifice (34) as a function of the pressure of the refrigerant in the inlet compartment (1210), according to a law
generally increasing, when the pressure of the refrigerant in the compartment
inlet (1210) is substantially between 80 bar and 135 bar. Dispositif de détente selon l'une des revendications précédentes, caractérisé en ce que le pointeau (134) est conformé pour maintenir une ouverture maximale du premier orifice (34), lorsque la pression du fluide réfrigérant dans le compartiment d'entrée (1210) est sensiblement supérieure ou égale à 135 bars.Expansion device according to one of the preceding claims, characterized in that that the needle (134) is shaped to maintain a maximum opening of the first orifice (34), when the pressure of the coolant in the inlet compartment (1210) is substantially greater than or equal to 135 bar. Dispositif de détente selon l'une des revendications précédentes, caractérisé en ce que les moyens de détente comprennent en outre un organe d'obturation (1271) comprenant un troisième orifice (37) et un obturateur (137) propre à obturer ledit troisième orifice.Expansion device according to one of the preceding claims, characterized in that the detent means further comprises a closure member (1271) comprising a third orifice (37) and a shutter (137) adapted to close said third orifice. Dispositif de détente selon la revendication 12 prise en combinaison avec l'une des revendications 9 à 11, caractérisé en ce que l'obturateur (137) est conformé pour obturer le troisième orifice (37), lorsque la pression du fluide réfrigérant dans le compartiment d'entrée (1210) est sensiblement inférieure à 135 bars, et pour ouvrir le troisième orifice (35), lorsque la pression du fluide réfrigérant dans le compartiment d'entrée (1210) est sensiblement
supérieure ou égale à 135 bars.Expansion device according to claim 12 taken in combination with one of claims 9 to 11, characterized in that the shutter (137) is shaped to close the third orifice (37), when the pressure of the refrigerant in the compartment inlet (1210) is substantially less than 135 bar, and to open the third port (35), when the refrigerant pressure in the inlet compartment (1210) is substantially
greater than or equal to 135 bars. Dispositif de détente selon l'une des revendications précédentes, caractérisé en ce que les moyens de détente variable (1211) comprennent en outre un système de ressort (350) agencé pour exercer une force sur le pointeau (134) s'opposant à la force exercée par la pression du fluide réfrigérant dans le compartiment d'entrée
(1210).Expansion device according to one of the preceding claims, characterized in that the variable expansion means (1211) further comprises a spring system (350) arranged to exert a force on the needle (134) opposing the force exerted by the pressure of the coolant in the inlet compartment
(1210). Dispositif de détente selon la revendication 14, caractérisé en ce que les moyens de
détente variable (1210) sont agencés dans un logement (1212) du compartiment d'entrée et en ce que le pointeau (134) comprend une tige de commande (135) sensiblement perpendiculaire à l'axe du premier orifice, fixée par une de ces extrémités au fond du logement, reliée mécaniquement à une paroi de séparation (340) sur laquelle s'exercent, d'un côté, la force du système de ressort (350) et de l'autre côté, la force due à la pression du fluide réfrigérant arrivant, de sorte que le pointeau est propre à se déplacer en translation, sensiblement perpendiculairement à l'axe de l'orifice.An expansion device according to claim 14, characterized in that the means for
variable trigger (1210) are arranged in a housing (1212) of the inlet compartment and in that the needle (134) comprises a control rod (135) substantially perpendicular to the axis of the first orifice, fixed by one of these ends at the bottom of the housing, mechanically connected to a partition wall (340) on which is exerted, on one side, the force of the spring system (350) and on the other side, the force due to the pressure of the refrigerant arriving, so that the needle is adapted to move in translation, substantially perpendicular to the axis of the orifice. Dispositif de détente selon l'une des revendications précédentes, caractérisé en ce que le fluide réfrigérant est le fluide R744.Expansion device according to one of the preceding claims, characterized in that the coolant is the fluid R744. Circuit de climatisation, fonctionnant avec un fluide réfrigérant et comprenant un compresseur (14), un refroidisseur de gaz (11), un dispositif de détente (12) et un évaporateur (13), caractérisé en ce que le dispositif de détente est tel que défini selon l'une des revendications 1 à 16.Cooling circuit, operating with a refrigerant and comprising a compressor (14), a gas cooler (11), an expansion device (12) and an evaporator (13), characterized in that the expansion device is such that defined according to one of claims 1 to 16.
EP05008382A 2004-04-09 2005-04-18 Improved expansion valve for air conditioning circuit Not-in-force EP1715264B1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP05008382A EP1715264B1 (en) 2004-04-09 2005-04-18 Improved expansion valve for air conditioning circuit
DE602005021618T DE602005021618D1 (en) 2004-04-09 2005-04-18 Improved relaxation device for an air conditioning cycle
AT05008382T ATE470115T1 (en) 2004-04-09 2005-04-18 IMPROVED RELAXATION DEVICE FOR A CLIMATE CYCLE
ES05008382T ES2345497T3 (en) 2004-04-09 2005-04-18 IMPROVED EXPANSION DEVICE FOR AIR CONDITIONING CIRCUIT.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0403766A FR2868830B1 (en) 2004-04-09 2004-04-09 IMPROVED RELIEF DEVICE FOR AIR CONDITIONING CIRCUIT
EP05008382A EP1715264B1 (en) 2004-04-09 2005-04-18 Improved expansion valve for air conditioning circuit

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EP1715264A1 true EP1715264A1 (en) 2006-10-25
EP1715264B1 EP1715264B1 (en) 2010-06-02

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EP05008382A Not-in-force EP1715264B1 (en) 2004-04-09 2005-04-18 Improved expansion valve for air conditioning circuit

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EP (1) EP1715264B1 (en)
CN (1) CN100541061C (en)
AT (1) ATE470115T1 (en)
DE (1) DE602005021618D1 (en)
ES (1) ES2345497T3 (en)
FR (1) FR2868830B1 (en)

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DE602005021618D1 (en) 2010-07-15
ATE470115T1 (en) 2010-06-15
US7243501B2 (en) 2007-07-17
US20050223740A1 (en) 2005-10-13
FR2868830B1 (en) 2012-11-30
CN1743772A (en) 2006-03-08
EP1715264B1 (en) 2010-06-02
CN100541061C (en) 2009-09-16
ES2345497T3 (en) 2010-09-24

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