FR2906016A1 - Refrigerant cycle device for air conditioner of e.g. hybrid vehicle, has evaporator to evaporate refrigerant, whose load density is less than/equal to threshold density when separator`s internal volume ratio is of specific value - Google Patents

Abstract

The device has an evaporator (14) to evaporate refrigerant e.g. ethane. A vapor/liquid separator (15) separates the refrigerant into liquid phase and vapor phase refrigerants. A separator`s internal volume ratio is greater than 0.87 when an internal volume of a low pressure side is the sum of internal volumes (Vacc, Veva) of the separator and the evaporator, and the separator`s volume ratio is a ratio between the volumes of the separator and the low pressure side. A load density of the refrigerant is less than/equal to threshold density when the separator`s volume ratio is 0.87.

Description

1 REFRIGERATION CYCLE DEVICE Description The present invention relates to

  relates to a refrigerant cycle device comprising a vapor / liquid separator, wherein the pressure of the refrigerant on the high pressure side can be set to a value greater than or equal to that of the critical refrigerant pressure. The refrigerant cycle device is suitable for use in a vehicle equipped with a motor. A supercritical refrigerant cycle device has heretofore been known, in which carbon dioxide is adopted as a refrigerant in one cycle, and the pressure of the refrigerant on the high pressure side is greater than or equal to the critical pressure in a state. supercritical. The critical temperature of the carbon dioxide refrigerant is low, for example about 31 C, in the supercritical refrigerant cycle device. In the case where the operation. when the outside air is at a high temperature, for example in summer, a device or a component in the cycle can be heated by the outside air at high temperature. This can increase the refrigerant temperature in the cycle to the critical temperature or higher.

  When the temperature of the refrigerant in the cycle is greater than or equal to the critical temperature that is to say when the refrigerant (for example carbon dioxide) is in a supercritical state, the liquefaction of the refrigerant is not caused by compression. Thus, when the charge density of the refrigerant in the refrigerant cycle device becomes larger, the refrigerant pressure in the cycle can be dramatically increased in conjunction with an increase in the refrigerant temperature in the cycle.

  When the refrigerant pressure in the cycle is raised above a pressure resistance value of a low pressure side device, the low pressure side device may be broken.  In particular, in the vehicle equipped with a motor, the device of the low pressure side can be heated not only by the outside air at high temperature 2906016 but also by the heat of the exhaust gas or the residual heat coming from the engine or being therein, resulting in further increase of the refrigerant temperature in the cycle.  Thus, the refrigerant pressure in the cycle tends to be further increased above the pressure resistance value of the device at the low pressure side.  In a supercritical refrigerant cycle device as described in JP-A-8-504501, a special reserve tank is connected to a low pressure side circuit via a valve, which is designed to be open when the refrigerant pressure in the cycle exceeds a predetermined pressure.  Thus, a portion of the refrigerant is received by the storage tank, thereby temporarily reducing the charge density of the refrigerant sealed in the cycle, thereby preventing an excessive increase of the refrigerant pressure in the cycle.  In the prior art, the valve is closed during normal operation, so that the reserve tank is separated from the low pressure side circuit.  However, the use of the special reserve tank and the valve leads to an increase in cost.  Because the reserve tank is separated from the low pressure side circuit in normal operation, the reserve tank can not have a vapor / liquid refrigerant separation function in the low pressure side circuit.  Thus, in addition to the reserve tank, a vapor / liquid separation mechanism must be provided.  This requires more space to mount the entire refrigerant cycle device, which leads to a deterioration in the mounting capacity of the refrigerant cycle device.  The degradation of the mounting capacity of the refrigerant cycle device for a vehicle as described above becomes problematic from a practical point of view because of the high stress associated with the mounting space.  In view of the foregoing problems, it is an object of the invention to provide a refrigerant cycle device which makes it possible to limit an increase of the refrigerant pressure 29060 in a cycle when stopping the operation of the cycle. without using a reserve tank.  In accordance with one aspect of the present invention, a refrigerant cycle device comprises a compressor (10) for sucking refrigerant and compressing the refrigerant to have a pressure above a critical refrigerant pressure, a radiator (12) ) for cooling the refrigerant discharged from the compressor (10), a decompression means (13) for decompressing coolant 10 from the refrigerant output side of the radiator (12), an evaporator (14) for evaporating the refrigerant at low pressure decompressed by the decompression means (13), and a vapor / liquid separator (15) disposed at the refrigerant suction side of the compressor (10) for separating refrigerant circulating from the evaporator (14) in a liquid phase refrigerant and a vapor phase refrigerant for storing therein the liquid phase refrigerant.  In the refrigerant cycle device, when the internal volume of the low pressure side (VL) is the sum (Vacc + Veva) of the internal volume (Vacc) of the vapor / liquid separator (15) and the internal volume (Veva) of the evaporator (14) and when the internal volume ratio of vapor / liquid separator (Racc) is the ratio (Vacc / VL) of the internal volume (Vacc) of the vapor / liquid separator (15) to the internal volume on the low pressure (VL) side, the internal vapor / liquid separator (Racc) volume ratio is set in a range of 0.18 or more.  When the internal vapor / liquid separator volume ratio (Racc-) is set in a range of 0.18 or more, the coolant charge density (pa) of the refrigerant cycle device becomes less than or equal to the target upper limit density (pmax).  This makes it possible to reduce the increase of the refrigerant pressure in the cycle when stopping cycle operation without using a reserve tank.  For example, the internal volume ratio of vapor / liquid separator (Racc) can be set in a range of 0.44 or higher.  Setting the internal vapor / liquid separator (Racc) volume ratio in a range of 0.44 or more can further reduce the increase in refrigerant pressure 40 in the cycle upon stopping the cycle operation. .  When the internal vapor / liquid separator volume ratio (Racc) is set higher, the refrigerant charge density (Pa) of the refrigerant cycle device can be decreased, thus further limiting the increase. the refrigerant pressure in the cycle when stopping cycle operation.  When the refrigerant charge density (ρ) becomes excessively small, the pressure at the low pressure side may decrease excessively at the start of the cycle, so that the increase in refrigerant pressure at the high pressure side may degrade.  In this case, it takes a long time to start the cycle.  When the internal vapor / liquid separator (Racc) volume ratio is set within a range of 0.87 or less, the refrigerant charge density (Pa) becomes greater than or equal to the target lower limit density. (pmin).  Therefore, this prevents the pressure of the low pressure side decreases excessively at the start of the cycle.  According to another aspect of the present invention, the refrigerant cycle device may further be provided with an internal heat exchanger (17) for exchanging heat between the low pressure refrigerant on the refrigerant suction side of the refrigerant. compressor (10) and the high-pressure refrigerant on the upstream side of the decompression means (13).  In this case, when the internal volume ratio of vapor / liquid separator (Racc) is the ratio (Vacc / VL) of the internal volume (Vacc) of the vapor / liquid separator (15) to the internal volume of the low pressure side (VL), and when the ratio of the duct volume on the high pressure side (Z) is the ratio (Vihe / Vgc) of the volume (Vihe) of a coolant duct on the high pressure side (17a) of the exchanger of internal heat (17) through which the high pressure refrigerant circulates on the internal volume (Vgc) of the radiator (12), the internal volume ratio of vapor / liquid separator (Racc) is set in the range Racc 0 , 39Z + 0.18.  Thus, the refrigerant charge density (pa) becomes lower than or equal to the target upper limit density (pmax) even with the internal heat exchanger (17), thereby reducing the pressure increase. refrigerant in the cycle when stopping cycle operation without using a reserve tank.  For example, the internal volume ratio of vapor / liquid separator (Racc) can be set in the range of Racc> - 0.45Z 5 + 0.44.  Alternatively, the internal vapor / liquid separator (Racc) volume ratio can be set in the range of Racc S 0.22Z + 0.87 and / or the pipe volume ratio of the high pressure side (Z) can be established in a range of not less than 0.05 and not more than 0.40.  In this case, the size of the internal heat exchanger can be reduced while the cycle efficiency (COP) can be improved in the refrigerant cycle device.  According to another aspect of the present invention, in the refrigerant cycle device, the internal volume (Vacc) of the vapor / liquid separator (15) can be set in a range defined by the following formula: Vacc ((pgc - pmax).  Vgc + (peva - pmax).  Veva) / (pmax - pacc) where Vgc is the internal volume of the radiator (12), Veva is the internal volume of the evaporator (14), pgc is the average refrigerant density in the radiator (12) in a high load cycle operation, peva is the average refrigerant density in the evaporator (14) in the high load cycle operation, pacc is the average refrigerant mass in the vapor / liquid separator (15) in the high load cycle operation, and pmax is the target upper limit refrigerant density.  In this case, the high load cycle operation is one in which the pressure of the high pressure refrigerant before being decompressed by the decompression means becomes a better operating pressure.  In this case, the refrigerant cycle device may further be provided with an internal heat exchanger (17) having therein a low pressure side refrigerant conduit (17b) through which the low pressure refrigerant on the refrigerant suction side of the compressor (10) flows, and a refrigerant line on the high pressure side (17a) through which the high pressure refrigerant on the upstream side of the decompression means (13) flows.  The internal heat exchanger (17) 2906016 6 may be designed to exchange heat between the low pressure refrigerant flowing through the low pressure side refrigerant line (17b) and the high pressure refrigerant flowing through the conduit. refrigerant on the high pressure side (17a).  In this case, the internal volume (Vacc) of the vapor / liquid separator (15) is set within a range defined by the following formula Vacc pgc-pmax).  Vgc + (pihe - pmax).  Vihe + (peva - pmax).  Veva) / (pmax - pacc) where Vgc is the internal volume of the radiator (12), Vihe is the internal volume of the refrigerant line on the high pressure side (17a), Veva is the internal volume of the evaporator (14) , pgc is the average refrigerant density in the radiator (12) in a high load cycle operation, pihe is the average refrigerant density in the high pressure side refrigerant conduit (17a) in the cycle operation at high load, peva is the average refrigerant density in the evaporator (14) in the high-load cycle operation, pacc is the average refrigerant mass in the vapor / liquid separator (15) in operation of high load cycle and pmax is the target upper limit refrigerant density.  Thus, the refrigerant charge density (Pa) becomes lower than or equal to the target upper limit density (pmax) even in the refrigerant cycle device provided with the internal heat exchanger (17), reducing thus increasing the refrigerant pressure in the cycle upon stopping cycle operation, without using a reserve tank.  The refrigerant cycle device may further be provided with a first refrigerant line (21) disposed between the refrigerant discharge side of the compressor (10) and the refrigerant inlet side of the radiator (12), a second conduit Refrigerant (22) disposed between the radiator coolant outlet side (12) and the refrigerant inlet side of the high pressure side pipe (17a), a third refrigerant pipe (23) disposed between the outlet side of the refrigerant of the high-pressure side duct (17a) and the refrigerant inlet side of the decompression means (13), a fourth refrigerant duct (24) disposed between the refrigerant outlet side of the decompression means (13); ) and the refrigerant inlet side of the evaporator (14), a fifth refrigerant line (25) disposed between the refrigerant outlet side of the evaporator (14) and the inlet side refrigerant of the vapor / liquid separator (15) and between the refrigerant outlet side of the vapor / liquid separator (15) and the refrigerant inlet side of the low pressure side conduit (17b), and a sixth refrigerant (26) disposed between the refrigerant outlet side of the low pressure side duct (17b) and the refrigerant suction side of the compressor (10).  In this case, an internal volume setting range (Vacc) of the vapor / liquid separator (15) is calculated, through the use of the internal volume (V'gc) and the refrigerant density. average (p'gc) of the radiator (12) corrected by the following formula, in place of the internal volume (Vgc) and the average refrigerant density (gcc) of the radiator (12), through the use of the internal volume (V'ihe) and the average coolant density (p'ihe) of the refrigerant line on the high pressure side (17a) corrected by the following formula, in place of the internal volume (Vihe) and the average refrigerant density (pihe) of the refrigerant conduit on the high pressure side (17a) and through the use of the internal volume (V'eva) and the average refrigerant density (p'eva) of the evaporator (14) corrected by the following formula, instead of the internal volume (Veva) and the density average refrigerant (peva) of the radiator (14), V'gc = Vgc + Vdpipe + Vhpipe 30 p'gc = (pgc.  Vgc + pdpipe.  Vdpipe + phpipe.  Vhpipe) / V'gc V'ihe = Vihe + Vcpipe p'ihe = (pihe.  Vihe + pcpipe.  Vcpipe) / V'ihe V'eva = Vevain + Veva + Vlpipe + Vihel + Vspipe + Vcomp p'evLa = (pevain.  Vevain + peva.  Veva + plpipe.  Vlpipe + 35 pihel.  Vihel + pspipe.  Vspipe + pcomp.  Vcomp) / V'eva where Vdpipe is the internal volume of the first refrigerant line (21), Vhpipe is the internal volume of the second refrigerant line (22), Vcpipe is the internal volume of the third refrigerant line (23) ), Vevain is the internal volume 40 of the fourth refrigerant line (24), Vlpipe is the internal volume of the fifth refrigerant line (25), Vihel is the internal volume of the low pressure side duct (17b), Vspipe is the internal volume of the sixth refrigerant pipe (26), Vcomp is the internal volume of the compressor 5 (10), pdpipe is the average refrigerant density of the first refrigerant pipe (21) in a cycle operation at high load, phpipe is the average refrigerant density in the second refrigerant line (22) in the high load cycle operation, pcpipe is the average refrigerant density in the third In the high-load cycle operation, the refrigerant density (23) is the average refrigerant density in the fourth refrigerant line (24) in the high-load cycle operation, plpipe is the refrigerant density. average in the fifth refrigerant line (25) in the high-load cycle operation, pihel is the average refrigerant density in the low-pressure side conduit (17b) in the high-load cycle operation, pspipe is the mass Average refrigerant volume in the sixth refrigerant line (26) in the high load cycle operation, and pcomp is the average refrigerant density in the compressor (10) in the high load cycle operation.  Therefore, the internal volume (Vacc) of the vapor / liquid separator (15) can be set, taking into account not only the internal volumes and the average refrigerant densities of the radiator (12), the evaporator ( 14) and the high pressure side duct (17a), but also the internal volumes and the average refrigerant densities of the compressor (10), the refrigerant lines (21 to 26) and the low pressure side duct (17b). .  Thus, the internal volume (Vacc) of the vapor / liquid separator (15) can be more conveniently set.  In the refrigerant cycle device described above, the target upper limit refrigerant density pmax may be a refrigerant density at 60 C and 11 MPa or may be a refrigerant density at 60 C and 10, 5 MPa.  Other objects and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which: Figure 1 is a simplified schematic of an air conditioner for a vehicle according to a first embodiment of the invention, Fig. 2 is a simplified perspective diagram showing a state installed on a vehicle of the air conditioner of the first embodiment. Fig. 3 is a graph showing a relationship between refrigerant temperatures and high pressure side refrigerant pressures with optimal cycle performance at a radiator outlet. Fig. 4 is a schematic diagram of a air conditioner for a vehicle according to a second embodiment; Fig. 5 is a graph showing the relationship between The high pressure side duct volume ratios (Racc) and the vapor / liquid separator volume ratio ranges (Z), FIG. 6 is a graph showing the relationship between the lengths (L) of An internal heat exchanger and cycle efficiencies (COPs). Fig. 7 is a graph explaining a range of high-side-side duct volume ratio setting. Fig. 8 is a simplified schematic of a conditioner. for a vehicle according to a third embodiment of the invention, and Figure 9 is a simplified diagram of an air conditioner 30 for a vehicle according to a fourth embodiment of the invention. .  (First Embodiment) A first embodiment of the invention will be described below with reference to Figures 1 to 3.  In this embodiment, a refrigerant cycle device is usually used for a vehicle air conditioner, as an example.  A compressor 10 obtains a driving force from a vehicle engine 11 (see FIG. 2) through an electromagnetic clutch, a belt (both not shown). ) and other, draws refrigerant (carbon dioxide in this example) and compresses the refrigerant to the critical pressure or higher.  In this embodiment, an external variable control type compressor equipped with a capacity control valve is adopted as a compressor 10.  The capacity control valve adjusts the discharge amount of the compressor 10 by changing a control current in accordance with a control signal outputted from a controller for air conditioning (not shown).  The compressor 10 includes the electromagnetic clutch, which controls the operation / shutdown of the compressor according to a demand signal outputted from the controller for air conditioning.  A radiator 12 is connected to the refrigerant discharge side of the compressor 10.  The radiator 12 exchanges heat between the high temperature and high pressure refrigerant in the supercritical state, discharged from the compressor 10 and the outside air (i.e. outside air of the passenger compartment) blown by an electric ventilation blower 12a, thereby cooling the refrigerant.  The radiator 12 is disposed in front of the vehicle engine 11 positioned at the most forward portion of the vehicle.  An unrepresented radiator grille is disposed in front of the radiator 12, to admit air during the movement of the vehicle.  An electric blower 12a blows the outside air taken from the radiator grille to the radiator 12.  A radiator (not shown) for generating heat from an engine coolant for the vehicle is disposed on the downstream side of the radiator airflow 12.  An expansion valve 13 serving as a decompression means is provided on the output side of the radiator 12.  The expansion valve 13 also serves as a pressure control valve whose degree of opening is adjusted so that the refrigerant pressure on the high pressure side of the cycle is the high target pressure.  A mechanical expansion valve whose degree of opening is adjusted by a mechanical mechanism, a fixed throttle valve whose degree of opening is fixed or an electric expansion valve whose degree of opening is electrically controlled , can be used as expansion valve: L3.  An evaporator 14 is connected to the output side of the expansion valve 13.  The evaporator 14 is designed to cool the supply air by allowing the low temperature, low pressure refrigerant decompressed by the expansion valve 13 to absorb the latent heat of vaporization from the outside air (air outside of the vehicle cabin) or the interior air (air inside the passenger compartment of the vehicle) blown by the electric ventilation blower 14a.  The evaporator 14 is disposed on the inside of a dashboard (not shown) in the front part inside the passenger compartment of the vehicle, while being housed in an inner unit housing (not shown) an air conditioner for a vehicle.  The electric ventilation blower 14a is disposed on the upstream side of the air flow of the evaporator 14 in an indoor air conditioning unit, and allows the indoor air or outside air to be introduced into it. through an unshown internal / external switching box is blown towards the evaporator 14.  A vapor / liquid separator (accumulator) 15 is connected to the outlet side of the evaporator 14.  The vapor / liquid separator 15 is a vapor / liquid separator for separating the refrigerant circulating from the evaporator 14 into a liquid phase refrigerant and a vapor phase refrigerant and for storing therein the refrigerant in excess in the cycle.  The vapor / liquid separator 15 has a reservoir body 15a formed in a vertically extending longitudinal cylindrical form.  The reservoir body 15a consists of an upper reservoir and a lower reservoir which are made of metal, such as aluminum, in this example, and which are integrally connected by connecting means, including included by welding.  A refrigerant inlet pipe 15b is disposed to penetrate the upper surface of the tank body 15a.  The refrigerant inlet line 15b forms a refrigerant inlet portion 40 to allow refrigerant from an outlet of the evaporator 14 to enter the tank body 15a.  A coolant outlet pipe 15c is formed to be bent into a U-shape and is disposed within the tank body 15a, a first end of the refrigerant outlet pipe 15c penetrating the upper surface of the body of the body. tank 15a to exit the tank.  The first end of the refrigerant outlet line 15c is connected to the suction side of the compressor 10.  The other end of the refrigerant outlet line 15c is directly opened in a space below a vapor / liquid separation plate 15d in an upper portion within the tank body 15a.  This opening portion on the top end of the refrigerant outlet line 15c constitutes a gaseous refrigerant suction portion for sucking gaseous refrigerant into the upper portion of the tank body 15a.  The vapor / liquid separation plate 15d is disposed in the upper portion of the tank body 15a with a predetermined distance spaced from an opening on the lower end of the refrigerant inlet line 15b.  The vapor / liquid separation plate 15d is formed into a bowl shape whose central portion is high and whose outer peripheral edge falls.  The vapor / liquid separation plate 15d is made of metal or resin and has a through hole through which the refrigerant outlet line 15c enters.  The vapor / liquid separation plate 15d is attached to the refrigerant outlet line 15c in the through-hole portion.  A space through which the refrigerant flows is formed between the outer peripheral edge of the vapor / liquid separation plate 15d.  and the inner wall surface of the tank body 15a.  The refrigerant inlet line 15b and the refrigerant outlet line 15c consist of metaltel only aluminum or the like.  The refrigerant inlet line 15b is inserted into the through hole on the upper surface of the tank body 15a and secured to the through-hole portion by connecting means such as by welding.  A first end of the refrigerant outlet conduit 15c is inserted into the through-hole portion on the upper surface of the reservoir body 15d and secured to the through-hole portion by the connecting means such as by welding.  An oil return hole 15e formed into a small circular cut shape having a diameter of about 1mm is open at the bottom of the U-shaped refrigerant outlet line 15c.  Thus, lubricating oil stored in the lower part of the tank body 15a can be sucked into the refrigerant outlet pipe 15c from the oil return hole 15e, thus preventing the lack of back to the compressor 10.  A vent hole 15f formed into a small circular shape having a diameter of about 1.5 mm is formed in the coolant outlet line 15c at the top 15 of the tank body 15a.  The vent hole 15f makes it possible to prevent the liquid refrigerant from entering the compressor 10 due to a decrease in the temperature of the compressor 10 when the cycle operation is stopped.  The refrigerant outlet line 15c is made of an aluminum material having a high thermal conductivity.  Thus, the refrigerant outlet line 15c exhibits good reactivity when a load on the evaporator 14 fluctuates compared with the case where the refrigerant outlet line 15c is made of a resin material.  In this example, the vapor / liquid separator 15 is disposed under a headlamp (not shown) in the frontmost part of the vehicle, which is insensitive to the heat of the exhaust gas or the residual heat from the engine. vehicle engine 11 or being in it.  This prevents the increase of the refrigerant temperature within the vapor / liquid separator due to the heat of the exhaust gas or the residual heat from or within the engine.  A safety valve 16 is designed to protect the device from the low pressure side by discharging the refrigerant into the atmosphere when the pressure of the low pressure side of the cycle is abnormally increased and is disposed between the refrigerant outlet side of the vapor separator. liquid 15 and the suction side of the compressor 10.  The safety valve 16 is a normally closed type valve mechanism 40 which normally maintains a closed valve state.  In this example, a valve responsive to known mechanical pressure can be used as a safety valve.  When the refrigerant pressure in the cycle abnormally increases to a predetermined value or more which is established for protection of the device from the low pressure side, the relief valve 16 is opened to allow the refrigerant to be discharged into the atmosphere.  This prevents the low pressure side device from breaking due to the abnormal increase in refrigerant pressure in the cycle.  In this example, the safety valve 16 is set to be open when the refrigerant pressure in the cycle reaches 11 MPa.  Another safety valve (not shown) is disposed on the discharge side of the compressor 10 and is designed to protect the device from the high pressure side by discharging the refrigerant into the atmosphere when the refrigerant pressure on the high pressure side of the cycle is abnormally high. increased.  In this embodiment, the maximum operating pressure of the high pressure side refrigerant pressure is set in a range of 12 MPa to 15.5 MPa.  In particular, the controller 10 is controlled so that the refrigerant pressure on the high pressure side does not exceed the maximum operating pressure.  Fig. 3 is a graph showing a relationship between the refrigerant temperatures at the radiator outlet 12 and the high pressure side refrigerant pressures having optimum cycle performance.  That is, FIG. 3 indicates that when the relationship between the refrigerant temperatures at the radiator outlet 12 and the high pressure side refrigerant pressures is represented by a straight line in FIG. cycle (COP) is maximum.  The lines interrupted in FIG. 3 indicate that the cycle efficiency (COP) is decreased by 5 with respect to the maximum value.  In the supercritical refrigerant cycle device for a vehicle, when the vehicle stops and the air appearing during the movement of the vehicle is calm, the warm air of the vehicle engine 11 is sucked into the radiator 12.  Thus, the refrigerant temperature at the outlet of the radiator 12 can frequently exceed 50 ° C.  In this case, as shown in FIG. 3, the controller 10 is controlled so that the refrigerant pressure on the high pressure side is about 12 MPa, which allows the high cycle efficiency (COP) to be presented.  Thus, the maximum operating pressure on the high pressure side is set to at least 12 MPa.  On the contrary; even when a refrigerant temperature at the radiator outlet 12 is highest, since the refrigerant temperature at the radiator outlet 12 does not exceed 70 ° C steadily, the maximum operating pressure at the high pressure side is set at a maximum of 15.5 MPa.  The critical temperature of the carbon dioxide refrigerant is low, for example about 31 ° C.  In the case where the operation of the refrigerant cycle device is stopped when the outside air is at a high temperature, for example in summer, a device or component in the cycle can be heated by the high temperature outside air. .  This can increase the refrigerant temperature in the cycle to the critical temperature or higher.  Furthermore, since the low pressure side device is heated not only by the high temperature outside air but also by the heat of the exhaust gas or the residual heat from the vehicle engine 11 or being in it. Herein, the refrigerant temperature in the cycle can be increased accordingly up to the critical temperature or higher.  In particular, the average temperature of the refrigerant in the cycle can reach a maximum of about 60 C.  In what follows, the maximum final average temperature of the refrigerant in the cycle is then called "refrigerant temperature in the maximum cycle T".  When the refrigerant temperature in the cycle is greater than or equal to the critical temperature, i.e., when the refrigerant (carbon dioxide) is in a supercritical state, the liquefaction of the refrigerant is not caused by compression.  Thus, when the charge density of the refrigerant (sealed refrigerant) 40 in the refrigerant cycle device becomes larger, the refrigerant pressure in the cycle can be dramatically increased in association with the increase. of the refrigerant temperature in the cycle.  Then, the refrigerant pressure in the cycle can reach a valve opening pressure of the safety valve 16 or more (in this example, 11 MPa or more), so that the safety valve 16 can be opened to allow the refrigerant to be discharged into the atmosphere.  Therefore, in this embodiment, an internal volume Vacc of the vapor / liquid separator 15 is suitably set to adjust the refrigerant charge density to an appropriate value, thereby reducing the excessive increase in pressure. refrigerant inside the cycle.  This makes it possible to prevent the refrigerant pressure in the cycle from reaching the valve opening pressure of the safety valve 16 when stopping cycle operation.  The internal volume Vacc of the vapor / liquid separator 15 will be described in detail.  The amount of refrigerant required for operation of the refrigerant cycle device is maximum when the refrigerant pressure on the high pressure side becomes the maximum operating pressure (hereinafter referred to as "high load cycle time").  Thus, the minimum required refrigerant charge amount W (kg) of the refrigerant cycle device is approximately determined by the following formula 1: W = pgc.  Vgc + peva.  Veva + pacc.  Vacc (Formula 1) where pgc is the average refrigerant density (kg / m 3) in the radiator 12 in the high-load cycle operation, peva is the average refrigerant density (kg / m 3) in the evaporator In the high load cycle operation, pacc is the average refrigerant density (kg / m 3) in the vapor / liquid separator in the high load cycle operation, Vgc is the internal volume (m 3) of the radiator 12, Veva is the internal volume (m3) of the evaporator 14 and Vacc is the internal volume (m3) of the vapor / liquid separator 15.  A refrigerant charge density pa when the refrigerant is sealed in the refrigerant cycle device by a refrigerant charge amount W is determined approximately by the following formula 2.  pa = W / (Vgc + Veva + Vacc) (Formula 2) The formulas (1) and (2) take into account only the internal volumes of the radiator 12, the evaporator 14 and the vapor / liquid separator 15 and do not take into account the internal volumes of the compressor 10 and the refrigerant line.  This is based on the following reason.  That is, the radiator 12 is a device on the high pressure side, and the refrigerant density of the radiator 12 during operation is important.  Thus, the internal volume of the radiator 12 has a significant influence on the amount of refrigerant charge (refrigerant seal amount) and the refrigerant charge density (refrigerant seal density).  Evaporator 14 is a low pressure side device, but the refrigerant density of evaporator 14 during cycle operation is relatively high.  Also, the internal volume of the evaporator 14 has a significant influence on the amount of refrigerant charge and the refrigerant charge density.  However, because the vapor / liquid separator 15 is the low pressure side device, the coolant density of the separator 15 during cycle operation 25 is low, but the internal volume of the separator 15 is large.  The internal volume of the vapor / liquid separator 15 has a significant influence on the amount of refrigerant charge and the refrigerant charge density.  For this reason, formulas (1) and (2) take into account the internal volumes of the radiator 12, the evaporator 14 and the vapor / liquid separator 15.  On the contrary, although the compressor 10 has a relatively large internal volume, most of its internal volume is occupied globally by a low pressure space.  During operation, the refrigerant in the compressor 10 is heated to 100 C or higher, resulting in an excessively low density and a low weight.  The internal volume of the compressor 10 and the refrigerant of the compressor 10 have little influence on the increase of the internal pressure at the end of the cycle.  Conversely, the compressor 10 is a part that acts to decrease the internal pressure.  From the above point of view, in order to determine the necessary volume of the accumulator (vapor / liquid separator 15), it will not be more advantageous for the internal volume and the amount of refrigerant of the compressor 10 to be taken into consideration. , which can act on the security side.  The refrigerant line on the low pressure side acts on the safety side in the same way, and is not taken into account for the calculation above.  The internal volume of the refrigerant line on the high pressure side is very small compared to the total internal volume of the refrigerant cycle device.  In this example, the refrigerant line having an inside diameter of about 5 mm is used, and the total internal volume of the high pressure side refrigerant line is only about 5 cm 3.  This has little influence on the amount of refrigerant charge and the refrigerant charge density.  For this reason, formulas (1) and (2) do not take into account the internal volumes of the compressor 10 and the refrigerant line.  However, it is evident that the internal volumes of the compressor 10 and the refrigerant line can be taken into account in formulas (1) and (2).  The internal volume Vacc of the vapor / liquid separator 25 is set so that the refrigerant charge density pa satisfies the following formula 3 so that the refrigerant charge density pa is less than or equal to a density of 30.degree. upper limit target pmax: pa pmax (Formula 3) where the target upper limit density pmax is the density of the refrigerant at the refrigerant temperature in the maximum cycle T and the target upper limit value of the refrigerant pressure in the cycle (hereinafter referred to as "target upper limit pressure") P.  Formula 3 can be converted using the above formulas (1) and (2) to the following formula 4 Vacc ((pgc-pmax).  Vgc + (peva - pmax).  Veva) / (pmax - pacc) (Formula 4) Thus, it is understood that the establishment of the internal volume 40 Vacc of the vapor / liquid separator 15 within a defined range by the formula 4 enables the density of the vapor to be reduced by refrigerant charge at target upper limit density pmax or less.  At this time, the sum of the internal volume Veva of the evaporator 14 and the internal volume

  Vacc of the vapor / liquid separator 15 ie (Veva + Vacc) is the internal volume of the low pressure side VL, the ratio (Vacc / VL) of the internal volume Vacc of the vapor / liquid separator 15 to the internal volume of the low side The pressure VL is a volume ratio of the vapor / liquid separator Racc, and the ratio (Vgc / VL) of the internal volume Vgc of the radiator 12 to the internal volume of the low pressure side VL is a radiator volume ratio Rgc. Formula 4 can be converted using the volume ratio of the vapor / liquid separator Racc and the ratio of the volume of the radiator Rgc to the following formula: Racc ((pgc-pmax) Rgc + peva-pmax) / ( Thus, it is understood that setting the vapor / liquid separator volume ratio Racc in a range defined by formula 5 allows the refrigerant charge density to be reduced to ground. voluminal upper limit target pmax or less. A specific example of calculating the volume ratio of vapor / liquid separator Racc on the basis of formula 25 will be described below. In this example of calculation, the target upper limit density pmax is approximated by the refrigerant temperature in the maximum cycle T of 60 C, and the target upper limit pressure P is set to 11 MPa, which is a press = ion This is to say that the target upper limit density pmax is replaced by the value 358.4 kg / m3, which is the density of the carbon dioxide at the same time. 60 C and 11 MPa. In this example of calculation, the actual measured values in the high-load cycle operation are used as the respective average refrigerant densities pgc, peva and pacc. As mentioned above, the maximum operating pressure of the high pressure side can be set in a range of 12 MPa to 15.5 MPa. In this example of calculation, the average refrigerant densities of 40 pgc, peva and pacc obtained when the refrigerant pressure of the high pressure side is 15.5 MPa, are used as the worst case. In particular, the density of the average refrigerant pgc in the radiator 12 is replaced by the value 439 kg / m 3, the density of the average refrigerant peva in the evaporator 14 is replaced by the value 366 kg / m 3 and the density The average pacc refrigerant in the vapor / liquid separator 15 is replaced by the value 192 kg / m 3. The internal volume Vgc of the radiator 12 may normally be set 3.5 times to 9 times larger than the internal volume of the low pressure side VL with respect to vehicle mounting space constraints. The radiator volume ratio Rgc can be in a range of 1/9 to 1 / 3.5. In this example of calculation, the ratio Rgc is replaced by the maximum value of the radiator volume ratio Rgc as the worst case (Rgc = 1 / 3.5). As a result, Racc> 0.18 can be obtained. Thus, by setting the volume ratio of the vapor / liquid separator Racc to satisfy Racc≥0.18, it is possible to prevent the refrigerant pressure in the cycle from reaching 11 MPa or more when an average refrigerant temperature in the cycle reaches 60 C. This makes it possible to prevent the refrigerant pressure in the cycle from reaching the valve opening pressure of the safety valve 16 or more, upon stopping the cycle operation. In this way, in this example, the appropriate setting of the internal volume Vacc of the vapor / liquid separator 15 makes it possible to reduce the increase of the refrigerant pressure in the cycle when the cycle operation is stopped without using 30 special reserve tank as used in the prior art. Likewise, the appropriate setting of the internal volume Veva of the evaporator 14 and not the internal volume Vacc of the vapor / liquid separator 15 makes it possible to reduce the increase of the refrigerant pressure in the cycle during the shutdown. the operation of the cycle. As mentioned above, the average refrigerant density in the vapor / liquid separator during cycle operation is lower than that in the evaporator 14 during cycle operation. In other words, a difference in average refrigerant density of the vapor / liquid separator 15 between the cycle operating time and the cycle operation stopping time is greater than that of the evaporator 14. The evaporator 14 is disposed inside the dashboard (not shown) in the front part inside the vehicle cabin, while being housed in an inner unit housing (not shown). an air conditioner of a vehicle. In summer, when the temperature of the cabin 10 increases to about 80 0C, the refrigerant temperature inside the evaporator 14 also increases to about 80 C. In contrast, the vapor / liquid separator 15 is disposed under a headlamp (not shown) at the frontmost part of the vehicle which is insensitive to the heat of the exhaust gas or the residual heat from the vehicle engine 11 or being therein. this. This makes it possible to reduce the refrigerant temperature in the vapor / liquid separator 15 when stopping the operation of the cycle at a level lower than that in the evaporator 14. For this reason, the reduction of the increase of the refrigerant pressure in the cycle by setting the internal volume Vacc of the vapor / liquid separator 15 is effective, as compared to reducing the increase of the refrigerant pressure in the cycle by setting the internal volume Veva of the evaporator 14. The relief valve 16 has some tolerance to the valve opening pressure, and thus can actually operate at a pressure of the valve opening pressure 30 or less (in this example at 11 MPa or less). In order to prevent such operation of the relief valve 16 at a pressure below the valve opening pressure, the high precision safety valve 16 must be used, which may result in increased costs. In this example of calculation, the target upper limit density pmax is replaced by the value 322.6 kg / m3, which is the density of carbon dioxide at the refrigerant temperature in the maximum cycle T of 60 ° C ( T = 60 C) and at the target upper limit pressure P of 40 10.5 MPa (P = 10.5 MPa). This makes it possible to obtain an internal volume setting range Vacc of the vapor / liquid separator 15, which makes it possible to further reduce the increase in the refrigerant pressure of the cycle when stopping the operation of the cycle. In particular, setting the volume ratio of the vapor / liquid separator Racc in a range of 0.44 allows the refrigerant pressure in the cycle to be 10.5 MPa or more when the average temperature is reached. Low pressure side refrigerant reaches about 60 ° C. Thus, the increase of the refrigerant pressure of the cycle upon stopping cycle operation can be further reduced. In this way, setting the internal volume Vacc of the vapor / liquid separator 15 limits the operation of the relief valve 16 without using the high precision safety valve 16, thereby reducing costs. In this example of calculation, the target upper limit density pmax is replaced by the value 269.9 kg / m3 which is the density of the carbon dioxide at the refrigerant temperature in the maximum cycle T of 60 C (T = 60 C) and at the target upper limit pressure P of 9.7 MPa (P = 9.7 MPa). This makes it possible to obtain an internal volume setting range Vacc of the vapor / liquid separator 15, which makes it possible to further reduce the increase in the refrigerant pressure of the cycle when stopping the operation of the cycle. In particular, by setting the volume ratio of vapor / liquid separator Racc in a range Racc? 0.83, the cycle refrigerant pressure can be prevented from reaching 9.7 MPa or more when the average coolant temperature of the low pressure side reaches about 60 C. Thus, the increase of the refrigerant pressure of the cycle during the stopping of the cycle operation can be further reduced, thus further reducing the costs of the safety valve 16. As can be seen from the description above, when the target upper limit pressure P is set smaller , the increase of the refrigerant pressure of the cycle at the end of the cycle operation can be further reduced. Even when the target upper limit pressure P is lowered slightly, the setting range 40 of the vapor / liquid separator volume ratio Racc is greatly changed. This means that the set value of the vapor / liquid separator ratio Racc is very important so as to reduce the increase of the refrigerant pressure in the cycle upon stopping the cycle operation. When the refrigerant charge density pa is less than or equal to 220 kg / m 3, the pressure on the low pressure side can be extremely reduced at the start of the cycle, and the increase of the high side pressure refrigerant pressure can degrade, which takes a long time to start the cycle. In this example, the compressor 10 obtains a driving force from the vehicle engine 11 and is thus often operated at a low number of revolutions. Thus, when the compressor 10 is started at a low number of turns, it takes a longer time to start the cycle. According to this embodiment, the internal volume Vacc of the vapor / liquid separator 15 is set in the following manner so as to ensure the refrigerant charge density of 220 kg / m 3 or more and to prevent the pressure of the Low pressure side decreases excessively when starting the cycle. That is, when the target lower limit density pmin of the refrigerant charge density pa is 220 kg / m3, the internal volume Vacc of the vapor / liquid separator 15 is set so that the refrigerant charge density pa satisfies the following formula 6 so that the coolant charge density pa is greater than or equal to the target lower limit density pmin. pa pmin (Formula 6) Formula 6 can be converted using Formulas 1 and 2 above to the following formula 7. Vacc 5 ((pgc-Amin) .Vgc + (peva-pmin) .Veva) / (pmin pacc) (Formula 7) Formula 7 can be converted using the vapor / liquid separator volume ratio above Racc and the radiator volume ratio Rgc to the following formula 8. Racc ((pgc-pmin). Rgc + peva - pmin) / (peva - pacc) 40 (Formula 8) 2906016 24 Thus, establishing the volume ratio of vapor / liquid separator Ra. In a range defined by Formula 8, cc can provide a refrigerant charge density pa of 220 kg / m3 or more, which prevents the lower side pressure from dropping excessively at the start of the cycle. A specific example of calculating the ratio of vapor / liquid separator Ra.cc based on formula 8 will be described below. The target lower limit density pmin is replaced by the value 220 kg / m3. The actual measured values of the average refrigerant density pgc, peva and pacc in the high-load cycle operation are used as the average refrigerant density mentioned above pgc, peva and pacc. In this example, the actual measurement values of the average refrigerant densities pgc, peva and pacc obtained when the high pressure side refrigerant pressure is 12 MPa are used. This is because the maximum operating pressure on the high pressure side is set within a range of 12 MPa to 15.5 MPa, and the worst case is where the necessary amount of refrigerant is less; that is, a case where the maximum operating pressure on the high pressure side is less, taking into consideration the upper limit value of the vapor / liquid separator volume ratio 25 Racc. In particular, the density of the average refrigerant pgc in the radiator 12 is replaced by the value 433 kg / m 3, the density of the average refrigerant peva in the evaporator 14 is replaced by the value 377.3 kg / m 3 and the mass The volume of medium refrigerant pacc in the vapor / liquid separator 15 is replaced by the value 171 kg / m 3. As mentioned above, the radiator volume ratio Rgc can be in the range of 1/9 to 1 / 3.5. In this calculation example, the radiator volume ratio Rgc is replaced by the minimum value as the worst case (Rgc = 1/9). As a result, Racc <0.87 can be obtained. Thus, by setting the volume ratio of the vapor / liquid separator Racc to satisfy Racc S 0.87, the density of 40 refrigerant charge pa of 220 kg / m3 or more can be ensured, thereby preventing that the pressure of the low pressure side decreases excessively at the start of the cycle. An example of the supercritical refrigerant cycle device for a vehicle in this embodiment will be described below. When the internal volume Vc of the compressor 10 is 200 cm -1, the internal volume Vgc of the radiator 12 is 130 cm3, the internal volume Veva of the evaporator 14 is 160 cm3, and the internal volume Vacc of the vapor separator 1.5 is 790 cc, the supercritical refrigerant cycle device for a vehicle is provided, which may have the foregoing effects. (Second Embodiment) The refrigerant cycle device of the second embodiment is designed by adding an internal heat exchanger 17 to the refrigerant cycle device of the first embodiment as shown in FIG. internal heat 17 exchanges the heat between the refrigerant flowing through the high-pressure side conduit 17a from the radiator 12 and the refrigerant 20 flowing through a low-pressure side conduit 17b to be sucked into the compressor 10, thereby releasing the heat from the refrigerant flowing from the radiator 12. This increases a difference in enthalpy of the refrigerant between an inlet and an outlet of the evaporator 14, thus allowing an improvement of the cycle efficiency (COP). In this embodiment, the relief valve 16 is disposed between the refrigerant outlet side of the evaporator 14 and the refrigerant inlet side of the vapor / liquid separator 15. When the internal heat exchanger 17 is disposed in the supercritical refrigerant cycle device for a vehicle as in this embodiment, the high pressure refrigerant is cooled in the high pressure side conduit 17a of the internal heat exchanger 17 to have a high density, so that a refrigerant charge amount W required for the cycle operation is increased compared to the first embodiment in which the internal heat exchanger 17 is not disposed. Therefore, when establishing the internal volume 40 Vacc of the vapor / liquid separator 15 as in the first embodiment, the coolant charge density may become excessively large. During the stopping of the cycle operation, the refrigerant pressure in the cycle can reach the valve opening pressure of the relief valve 16 or a higher pressure thereon. Thus, according to this embodiment, the internal volume Vacc of the vapor / liquid separator 15 is set taking into consideration the internal heat exchanger 17, so that the refrigerant charge density is set to a value of appropriate. This prevents the refrigerant pressure in the cycle from reaching the valve opening pressure of the relief valve 16 or a higher pressure therein during the stopping of the cycle operation. First, a minimum required refrigerant charge amount W (kg) in the refrigerant cycle device is determined approximately by the following formula 9. W = pgc. Vgc + pihe. Vihe + peva. Veva + pacc. Vacc (Formula 9) where pihe is the average refrigerant density (kg / m3) in the high-pressure side conduit 17a in the high-load cycle operation, and Vihe is the internal volume (m3) of the side-conduit. high pressure 17a. The other values may be identical to those of the first embodiment. The refrigerant charge density pa when the refrigerant is charged to the refrigerant cycle device by a refrigerant charge amount W (refrigerant seal amount) is determined approximately by the following formula 10: pa = W / (Vgc + Vihe + Veva + Vacc) (Formula 10) Formulas 9 and 10 take into account only the internal volume of the duct on the high pressure side 17a of the internal heat exchanger 17, and not the internal volume of the duct 17. on the low pressure side 17b. This is based on the following reason. That is, the high pressure side conduit 17a which is the device on the high pressure side has a high refrigerant density during cycle operation. The internal volume of the conduit 17a is small, but contributes a great deal to the amount of refrigerant charge W and refrigerant charge mass pa. For this reason, the internal volume of the high pressure side conduit 17a is considered in this embodiment. In contrast, the internal volume of the low pressure side conduit 17b is very small compared to the total internal volume of the refrigerant cycle device. In the low-pressure side conduit 17b, the refrigerant is heated by the high-side refrigerant so that the coolant density becomes small during the cycle operation. The contribution of the low pressure side conduit 17b to the refrigerant charge amount W and the refrigerant charge mass pa is smaller than that of the low pressure line. Thus, the internal volume of the duct on the low pressure side 17b is not taken into consideration. However, it is evident that the internal volume of the low pressure side conduit 17b can be taken into account in formulas 9 and 10. As in the first embodiment, the internal volume Vacc of the vapor / liquid separator 15 can be established so that the charge density of refrigerant pa satisfies the formula mentioned above 3. That is, formula 3 can be converted using the above formulas 9 and 10 into the following formula 11. Vacc ((pgc-pmax) Vgc + (pihe-pmax) Vihe + (peva -pmax) Veva) / (pmax - pacc) (Formula 11) Thus, it is understood that the establishment of the internal volume Vacc of the vapor / liquid separator 15 within a range defined by formula 11 above allows the refrigerant charge density to be reduced to the target upper limit pmax or less even when the internal heat exchanger 17 is planned. The ratio (Vihe / Vgc) of the internal volume Vihe of the high pressure side duct 17a to the internal volume Vgc of the radiator 12 is a duct volume ratio of the high pressure side Z. The formula 11 can be transformed using the ratio of the volume of the vapor / liquid separator Racc, the ratio of the radiator volume Rgc and the volume ratio of the conduit of the high pressure side Z as described above, to the following formula 12: Racc ((pihe - pmax) Rgc Z + (pgc-pmax) Rgc + (peva-pmax) / (peva-pacc) (Formula 12) Thus, establishing the volume ratio of vapor / liquid separator Racc in a range defined by Formula 12 reduces the refrigerant charge density to the target upper limit pmax or lower density even when the internal heat exchanger 17 is provided A specific example of calculating the vapor separator volume ratio / liquid Racc based on the formula 12 will be described below. The target upper limit density pmax is replaced by the value 358.4 kg / m 3, which is the density of carbon dioxide at the refrigerant temperature in the maximum cycle T = 60 ° C. and at the higher target pressure P. = 11 MPa. The actual measured values of the average refrigerant densities pgc, pihe, peva and pacc when the high pressure side refrigerant pressure is 15.5 MPa, are used as the average refrigerant density mentioned above pgc , pihe, peva and pacc. The reason why the average pgc, pihe, peva and pacc refrigerant densities obtained when the high pressure side refrigerant pressure is 15.5 MPa are used is the same as that of the first embodiment. In particular, the density of the average refrigerant pgc in the radiator 12 is replaced by the value 439 kg / m 3, the average refrigerant density pihe in the conduit of the high-pressure side 17a of the internal heat exchanger 17 is replaced the value of 599 kg / m3, the average refrigerant density peva in the evaporator 14 is replaced by the value 366 kg / m3 and the average refrigerant density pacc in the vapor / liquid separator 15 is replaced by the value 192 kg / m3. As in the first embodiment, the ratio Rgc is replaced by the maximum value of the radiator volume ratio Rgc as the worst case (Rgc = 1 / 3.5). As a result, the ratio Racc 0.39Z + 0.18 can be obtained. Thus, by setting the volume ratio of the vapor / liquid separator Racc to satisfy the ratio of 0.39Z + 0.18, it is possible to prevent the refrigerant pressure in the cycle from becoming 11 MPa or more when an average coolant temperature of the low pressure side reaches 60 C even with the internal heat exchanger 17. This 5 makes it possible to prevent the refrigerant pressure in the cycle from reaching the valve opening pressure of the valve safety device 16 or a pressure greater than this. In the graph of FIG. 5, the straight line A represents Racc = 0.39Z + 0.18. The graph indicates that by setting the volume ratio of vapor / liquid separator Racc in a range above continuous line A, it is possible to prevent the refrigerant pressure in the cycle from reaching the valve opening pressure. of the safety valve 16 or a pressure above it. In the above-mentioned calculation example, when the target upper limit density pmax is changed to 322.6 kg / m3, which is the density of carbon dioxide at the refrigerant temperature in the maximum cycle T = 60 C and at the target upper limit pressure P = 10.5 MPa, an internal volume setting range Vacc of the vapor / liquid separator 15 can be obtained so as to further reduce the pressure increase of refrigerant in the cycle during the cycle stop. In particular, as shown in the graph of FIG. 5, by setting the volume ratio of the vapor / liquid separator Racc in the range of Racc 0.45 + 0.44, the refrigerant pressure in the cycle can be prevented. to 10.5 MPa or more when the average coolant temperature on the low pressure side reaches 60 ° C., thereby further reducing the increase of the refrigerant pressure in the cycle during the cycle stop. In the graph of FIG. 5, the straight line B represents Racc = 0.45Z + 0.44. The graph indicates that by setting the volume ratio of the vapor / liquid separator Racc in a range above the straight line B, it can be further prevented that the refrigerant pressure in the cycle reaches the opening pressure of valve of the safety valve 16 or a pressure above it. In the calculation example mentioned above, when the target upper limit pmax density is changed to 2906016 26 kg / m3, which is the density of carbon dioxide at the refrigerant temperature in the cycle. maximum T = 60 C and at the target upper limit pressure P = 9.7 MPa, one can obtain an internal volume setting range Vacc of the vapor / liquid separator 15, which makes it possible to reduce the refrigerant pressure in the cycle when stopping the cycle. In particular, the graph of FIG. 5 indicates that by setting the volume ratio of the vapor / liquid separator Racc in a range of 0.54Z + 0.83accapor, it can be prevented that the refrigerant pressure in the cycle reaches 9.7 MPa or higher when the average coolant temperature on the low pressure side reaches 60 C, further reducing the increase in: The refrigerant pressure of the cycle when the cycle is stopped. When the refrigerant charge density pa is less than or equal to 220 kg / m 3, the pressure at the low pressure side dramatically decreases when the cycle is started, and the refrigerant pressure increase at the high pressure side increases. degrades, thus taking a long time to start the cycle. As in the first embodiment, in this embodiment, the internal volume Vacc of the vapor / liquid separator 15 is set as follows to provide the refrigerant charge density pa of 220 kg / m 3 or more, in accordance with the present invention. thus preventing the pressure on the low pressure side from decreasing excessively at the start of the cycle. That is, formula 6 described in the first embodiment can be transformed using the above formulas 9 and 10 into the following formula 13. Vacc 5 ((pgc - pmin), Vgc + (pihe - pmin), Vihe + 30 (peva - pmin), Veva) / (pmin - pacc) (Formula 13) Formula 13 is transformed using the volume ratio of vapor / liquid separator mentioned above Racc, the radiator volume ratio Rgc and the pipe volume ratio of the high pressure side Z, in the following formula 14. Racc ((pihe-pmin). (pgc - pmin) Rgc + (peva - pmin) / (peva - pacc) (Formula 14) Thus, establishing the volume ratio of vapor / liquid separator Racc in a range defined by formula 14 can provide the refrigerant charge density pa of 40 220 kg / m3 or more, thereby preventing the pressure on the low pressure side from excessively decreasing at cycle start, a specific example of calculating the separator volume ratio of Vapor / liquid Racc based on Formula 14 will be described below.The target lower limit density pmin is re moved by the value 220 kg / m3. The actual measured values of the average refrigerant densities pgc, pihe, peva and pacc when the high pressure side refrigerant pressure is 12 MPa are used as the average refrigerant density mentioned above pgc, pihe, peva and pacc. The reason why the respective average refrigerant densities gc, pihe, peva and pacc obtained when the high pressure side refrigerant pressure is 12 MPa are used is the same as that of the first embodiment. In particular, the average refrigerant density pgc in the radiator 12 is replaced by the value 433 kg / m 3, the average refrigerant density pihe in the high-pressure side conduit 17 a of the internal heat exchanger 17 is replaced the value 625 kg / m3, the average refrigerant density peva in the evaporator 14 is replaced by the value 377.3 kg / m3 and the average refrigerant density pacc of the vapor / liquid separator 15 is replaced by the value 171 kg / m3. As in the first embodiment, the radiator value ratio Rgc is replaced by the minimum value as the worst case (Rgc = 1/9). As a result, the relationship Racc <0.22Z + 0.87 can be obtained. Thus, setting the vapor / liquid separator volume ratio Racc in a range Racc S 0.22Z + 0.87 can ensure the refrigerant charge density pa of 220 kg / m3 or more, thereby preventing that the pressure of the low pressure side decreases extremely at the start of the cycle. In the graph of FIG. 5, the straight line C represents Racc = 0.22 + 0.87. The graph indicates that by setting the volume ratio of the vapor / liquid separator Racc in a range below the continuous line C, it is possible to prevent the pressure of the low pressure side from excessively decreasing at the start of the cycle. An example of the supercritical refrigerant cycle device 40 for a vehicle of this embodiment will be described below. The internal volume Vc of the compressor 10 is 200 cm3, the internal volume Vgc of the radiator 12 is 130 cm3 and the internal volume Vihe of the pipe on the high pressure side 17a of the internal heat exchanger 17 is 20 cm3. The internal volume of the low pressure side duct 17b of the internal heat exchanger 17 is 6.4 cm3, the internal volume Veva of the evaporator 14 is 160 cm3 and the internal volume Vacc of the liquid vapor separator 15 is 790 cm3. In this case, the supercritical refrigerant cycle device for a vehicle 10 is provided, which: L can have the foregoing effects. More particularly, the internal heat exchanger 17 will be described below. Fig. 6 is a graph showing the relationship between the lengths L of the internal heat exchanger 17 and the cycle efficiencies (COP). As can be seen from FIG. 6, when the length L of the internal heat exchanger 17 is less than or equal to 2000 mm, when the length L of the internal heat exchanger 17 becomes longer, the cycle efficiency (COP) is improved. When the length L of the internal heat exchanger 17 exceeds 2000 mm, even the internal heat exchanger 17 has a long length L, a generally constant cycle efficiency (COP) is obtained. On the contrary, when the length L of the internal heat exchanger 17 becomes larger, the body of the internal heat exchanger 17 is increased in size, whereby the mounting ability (arrangement performance) of the internal heat exchanger 17 on the vehicle is degraded. Thus, preferably, the length L of the internal heat exchanger 17 is set in a range of 500 mm to 2000 mm to achieve both improved cycle efficiency (COP) and prevention. In this example, the internal diameter of the duct at the high pressure side of the internal heat exchanger is set to 5 mm. Thus, as shown in FIG. 7, when the length L of the internal heat exchanger 17 is set within a range of 500 mm to 2000 mm, the internal volume Vihe of the duct on the high pressure side 17a of the heat exchanger internal heat 17 is set in a range of 10 cm3 to 40 cm3. On the contrary, in the supercritical refrigerant cycle device for a vehicle, the internal volume Vgc of the radiator 12 is normally set in a range of 100 cc to 210 cc relative to the constraints of the vehicle mounting space. . That is, the internal volume Vihe of the high pressure side duct 17a of the internal heat exchanger 17 and the internal volume Vgc of the radiator 12 have a relationship represented by a shaded area shown in FIG. The volume ratio of the high pressure side duct Z (Z = Vihe / Vgc) is set in a range of 0.05 to 0.40. In other words, the establishment of the duct volume ratio of the high pressure side Z (Z = Vihe / Vgc) in a range of 0.05 to 0.40 makes it possible to obtain at the same time the efficiency improvement. (Third embodiment) Although in the second embodiment, the evaporator 14 is comprised of In a third embodiment, the evaporator 14 consists of two evaporators, which consist of an evaporator 141 for a front seat and an evaporator 142 for a rear seat as shown in FIG. The front seat evaporator 141 cools the supply air by allowing the low temperature, low pressure refrigerant decompressed by a front seat expansion valve 131 to absorb the latent heat of vaporization from the outside air (this is to say the air outside 1) or indoor air (i.e., air inside the passenger compartment) blown by the electric ventilation blower 141a. The front seat evaporator 141 is disposed on the inside of the dashboard (not shown) in the front part inside the passenger compartment of the vehicle, while being housed in the inner unit housing (not shown ) of the vehicle air conditioner. The electric ventilation blower 141a is disposed on the upstream side of the air flow of the front seat evaporator 141 in the indoor air conditioning unit, and allows the indoor air or outside air to be introduced into the indoor air conditioning unit. this via 2906016 34 of the indoor / outdoor switch box (not shown) is blown to the front seat evaporator 141. The vapor / liquid separator 15 is connected to the outlet side of the front seat evaporator 141. The relief valve 16 is disposed between the refrigerant outlet side of the front seat evaporator 141 and the refrigerant inlet side of the vapor / liquid separator 15. A rear seat expansion valve 132 is disposed parallel to the front seat expansion valve 131 with respect to a refrigerant flow from the compressor 10. The rear seat evaporator 142 is connected to the outlet side of the air valve. The rear seat evaporator 142 is disposed parallel to the front seat evaporator 141 relative to the refrigerant flow from the compressor 10. The front seat evaporator 142 cools the rear seat evaporator 142. supply air by allowing the low-temperature, low-pressure refrigerant decompressed by the rear seat expansion valve 132 to absorb latent heat of vaporization from the outside air (i.e. the outside of the passenger compartment) or the interior air (that is to say the air inside the passenger compartment) blown by the electric ventilation blower 142a. In this example, the refrigerant flowing from the rear seat evaporator 142 is joined to the refrigerant flowing from the vapor / liquid separator 15 at a junction point 18 on the downstream side of the vapor / liquid separator. 15, and the combined refrigerants circulate in the low-pressure side conduit 17b of the internal heat exchanger 17. When the liquid-phase refrigerant exists in the refrigerant flowing from the rear seat evaporator 142, the refrigerant liquid phase in the conduit of the low pressure side 17b of the internal heat exchanger 17 exchange of heat with the refrigerant flowing through the conduit 35 of the high pressure side 17a from the radiator 12 to be evaporated. Thus it is not required that the refrigerant flowing from the rear seat evaporator 142 flows in the vapor / liquid separator 15, because the internal heat exchanger 17 is provided. The rear seat evaporator 142 is disposed in a rear portion of the passenger compartment of the vehicle, while being housed in the inner unit housing (not shown) of the vehicle air conditioner. The electric ventilation blower 142a is disposed on the upstream side of the air flow of the rear seat evaporator 142 in the indoor air conditioning unit, and is adapted to blow the indoor air and / or air. outside air introduced through the indoor / outdoor air switch box (not shown) to the evaporator 14 (front seat evaporator 141 and rear seat evaporator 142, in this embodiment). As a refrigerant line 19 between the radiator outlet side 12 and the inlet side of the high pressure side conduit 17a of: The internal heat exchanger 17 is used a conduit having an internal diameter dl of 5 mm (dl = 5 mm) and a thickness tl of 2 mm (tl = 2 mm). As a refrigerant line 20 between the outlet side of the rear seat evaporator 142 and the junction point 18, a line having an inside diameter d 2 of 8 mm (d 2 = 8 mm) and a thickness t 2 of 1.5 mm (t2 = 1.5 m). In this embodiment, the evaporator 14 is made up of two evaporators, namely, the front seat evaporator 141 and the rear seat evaporator 142. The internal volume Vacc of the vapor / liquid separator 15 is set from the following way to adjust the refrigerant charge density to an appropriate value, which prevents the refrigerant pressure in the cycle when stopping the cycle from reaching the valve opening pressure of the safety valve 16 or a pressure greater than this. That is, in this embodiment, the average refrigerant density peval in the front seat evaporator 141 is approximated to be substantially the same as the average refrigerant density peva2 in the seat evaporator back 142 in the high load cycle operation, so that peva = peval or peva = peva2 is substituted in formula 9. The reason that the average refrigerant density peval in the front seat evaporator 141 may be 40 approximated to be substantially identical to the average refrigerant density peva2 in the rear seat evaporator 142 in the high-load cycle operation is that the two evaporators 141 and 142 generally have the same evaporation pressure therein since the front seat evaporator 141 is connected to the rear seat evaporator 142 via the ref 20. When the internal volume Veva is obtained by adding the internal volume Veval of the front seat evaporator 141 and the internal volume Veva2 of the rear seat evaporator 142 (Veva = Veval + Veva2), and that the volume This obtained is substituted in formulas 9 and 10, formulas 11 and 12 can be obtained, as in the second embodiment. Also, in this embodiment, setting the internal volume Vacc of the vapor / liquid separator 15 in a range defined by formula 11, or setting the volume ratio of vapor / liquid separator Racc in a range defined by formula 12 allows to reduce the density of charge of

  condenser at the upper limit density target pmax or less. As a result, the refrigerant pressure in the cycle can be prevented from reaching the valve opening pressure of the relief valve 16 or a higher pressure thereto during the stopping of the cycle operation.

In this embodiment, the rear seat evaporator 142 is added to the structure of the second embodiment mentioned above. The internal volume Vacc of the vapor / liquid separator 15 can be set in the following manner to prevent the pressure of the low pressure side from decreasing excessively in the course of cycling operation. That is, when peva = peval or peva = peva2 in formula 9 and that Veva = Veval + Veva2 in formulas 9 and 10, formulas 13 and 14 can be obtained as in the second embodiment.

Therefore, in this embodiment, setting the volume ratio of vapor / liquid separator Racc in a range defined by formula 14 enables the refrigerant charge density pa of 220 kg / m 3 to be ensured. Moreover, thus preventing the pressure of the low pressure side from decreasing excessively at the start of the cycle operation. In the second embodiment above, the setting range of the internal volume Vacc of the vapor / liquid separator 15 is calculated using the above formulas 13 and 14, taking only the internal volumes Vgc, Vihe and Veva and the average refrigerant densities pgc, pihe, peva of the radiator 12, the evaporator 14 and the pipe of the high-pressure side 17a of the internal heat exchanger 17 are considered. this embodiment, in addition to these, the internal volumes and the average refrigerant densities of the compressor 10, the respective refrigerant lines and the low-pressure side conduit 17b of the internal heat exchanger 17 are also took into consideration.

Figure 9 shows a whole structure of an air conditioner for a vehicle according to a fourth embodiment. Fig. 9 is the same as Fig. 4 except that the reference characters for the first to sixth refrigerant lines 21 to 26 are added. The first refrigerant line 21 is a refrigerant line between the discharge side of the compressor 10 and the inlet side of the radiator 12. The second refrigerant line 22 is a refrigerant line between the radiator outlet side 12 and the inlet side of the radiator 12. the third refrigerant line 23 is a refrigerant line between the outlet side of the high-pressure side conduit 17a and the inlet side of the expansion valve 13.

The fourth refrigerant line 24 is a refrigerant line between the outlet side of the expansion valve 13 and the inlet side of the evaporator 14. The fifth refrigerant lines 25 constitute a refrigerant line between the outlet side of the evaporator 14 and the inlet side of the vapor / liquid separator 15, and a refrigerant line between the outlet side of the vapor / liquid separator 15 and the inlet side of the low pressure side conduit 17b. The sixth refrigerant line 26 is a refrigerant line between the outlet side of the low pressure side duct 17b and the suction side of the compressor 10.

In the fourth embodiment, in the formula 13 of the second embodiment as described above, the internal volume V 'gc and the average refrigerant density p'gc of the radiator 12 modified by the following formulas 15 and 16 are used in place of the internal volume Vgc and the average refrigerant density pgc of the radiator 12. And the internal volume V'ihe and the average refrigerant density p'ihe of the high-side refrigerant duct Pressure 17a modified by the following formulas 17 and 18 are used in place of the internal volume Vihe and the average refrigerant density pihe of the refrigerant line of the high pressure side 17a. In addition, the internal volume V'eva and the average refrigerant density p'eva of the evaporator 14 modified by the following formulas 19 and 20 are used, in place of the internal volume Veva and the refrigerant density. average peva of the evaporator 14. V'gc = Vgc + Vdpipe + Vhpipe (Formula 15) p'gc = (pgc, Vgc + pdpipe, Vdpipe + phpipe, Vhpipe) / V'gc (Formula 16) 20 V'ihe = Vihe + Vcpipe (Formula 17) p'ihe = (pihe, Vihe + pcpipe, Vcpipe) / V'ihe (Formula 18) V'eva = Vevain + Veva + Vlpipe + Vihel + Vspipe + Vcomp (Formula 19) 25 p 'eva = (pevain, Vevain + peva, Veva + plpipe, Vlpipe + pihel, Vihel + pspipe, Vspipe + pcomp Vcomp) / V'eva (Formula 20) In formula 15, Vdpipe is the internal volume (m3) of the first refrigerant pipe 21, and Vhpipe is the internal volume (m3) of the second refrigerant pipe 22. In the formula 16, pdpipe is the average refrigerant density (kg / m3) in the first refrigerant pipe in the high load cycle operation, and phpipe is the average refrigerant density (kg / m 3) in the second refrigerant line 22 in the high load cycle operation. In formula 17, Vcpipe is the internal volume (m3) of the third refrigerant line 23. In formula 18, pcpipe is the average refrigerant density (kg / m3) in the third refrigerant line 23 in the high load cycle operation. In formula 19, Vevain is the internal volume (m3) of the fourth refrigerant line 24, Vspipe is the internal volume (m3) of the fifth refrigerant line 25, Vihel is the internal volume (m3) of the duct on the other side. at low pressure 17b, Vspipe is the internal volume (m3) of the sixth refrigerant pipe 26 and Vcomp is the internal volume (m3) of the compressor 10. In this example, the internal volume of a compressor housing 10 is used in As the internal volume of the compressor 10. In the formula 20, the average refrigerant density (kg / m 3) in the fourth refrigerant line 24 in the high-load cycle operation, and pspipe is the density of the refrigerant. medium refrigerant (kg / m3) in the fifth refrigerant line 25 in the high load cycle operation. Further, pihel is the average refrigerant density (kg / m3) in the low-pressure side conduit 17b in the high-load cycle operation, pspipe is a mean refrigerant density (kg / m3) in the sixth refrigerant line 26 in the high-load cycle operation and pcomp is the average refrigerant density (kg / m3) in the compressor 10 in the high-load cycle operation. In this example, the average refrigerant density of the compressor housing 10 is used as the average refrigerant density of the compressor 10. That is, the internal volume V 'gc represented in the formula 15 is the total internal volume of the radiator 12, the first refrigerant pipe 21 and the second refrigerant pipe 22. The average refrigerant density p'gc in the formula 16 is the average refrigerant density in the radiator 12, the first refrigerant pipe 21 and the second refrigerant pipe 22.

The internal volume VII in formula 17 is the total internal volume of the high pressure side conduit 17a and the third refrigerant conduit 23. The average refrigerant density in formula 18 is the density of total average refrigerant of the high side 40 pressure line 17a and the third refrigerant line 23.

The internal volume V'eva in the formula 19 is the total internal volume of the fourth refrigerant line 24, the evaporator 14, the fifth refrigerant line 25, the low-pressure side conduit 17b, the sixth The average refrigerant density p'eva in the formula 20 is the total average refrigerant density of the fourth refrigerant line 24, the evaporator 14, the fifth refrigerant pipe 25, the low-pressure side duct 17b, the sixth refrigerant line 26 and the compressor 10. In this way, the internal volume setting range Vacc of the vapor / liquid separator 15 calculated by the formula 13 is determined, taking into account not only the internal volumes and the average refrigerant densities of the radiator 12, the evaporator 14 and the high-side conduit. pressure 17a but also the internal volumes and the average refrigerant density of the compressor 10, the respective refrigerant lines 21 to 26 and the duct on the low pressure side 17b. Thus, the internal volume Vacc of the vapor / liquid separator 15 can be more suitably established. As in the second embodiment, as the average refrigerant densities, pdpipe, phpipe, pcpipe, pevain, plpipe, pihel, pspipe and pcomp in formulas 16, 18 and 20 mentioned above can be used as the values. actual average refrigerant densities obtained when the high pressure side refrigerant pressure is 12 MPa. For example, the average refrigerant density of the first refrigerant pipe 21 may be replaced by the value 251 kg / m3, the average refrigerant density phpipe in the second refrigerant pipe 22 may be replaced by the value 524. kg / m3, and the average coolant density pcpipe in the third refrigerant line 23 can be replaced by the value 720 kg / m3. Similarly, the average fresh refrigerant density in the fourth refrigerant line 24 can be changed to 453 kg / m3, the average refrigerant density in the fifth refrigerant pipe 25 can be replaced by the value 192 kg / m3, and the density of average refrigerant pihe in the conduit of the low pressure side 17b can be replaced by the value 170 kg / m3. In addition, the average refrigerant density pspipe in the sixth refrigerant line 26 can be replaced by the value 132 kg / m3 and the average refrigerant density pcomp in the compressor 10 can be replaced by the value 192 kg / m3 . (Other Embodiments) Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it should be noted that various changes and modifications will become apparent to humans. art. For example, although in each of the above-mentioned embodiments, the invention is applied to a supercritical refrigerant cycle device using carbon dioxide as a refrigerant, the invention is not limited thereto. . It will be apparent that the invention can be applied to any refrigerant cycle device using any refrigerant other than carbon dioxide, such as ethylene, ethane, nitric oxide and the like. Although in each embodiment described above, the driving force generated by the vehicle engine 11 is transferred to the compressor 10 via an electromagnetic clutch, the invention is not limited thereto. In place of the electromagnetic clutch, a pulley may intervene, which is designed to interrupt the transfer of the motive force generated by the motor 11 to the compressor 10 by being mechanically broken when the driving force reaches a predetermined value. Although in each of the above embodiments, the external variable control type compressor is employed as the compressor 10, a constant displacement compressor or an internal variable compressor may be employed as a compressor 10. Although in each of the embodiments above, the invention is applied to the vehicle equipped with the vehicle engine 11, the invention can be applied to a hybrid vehicle equipped with the vehicle engine 11 and an electric motor 40, which a fuel cell vehicle 2906016 42 with a fuel cell is called without installing the vehicle engine thereon. When the invention is applied to the hybrid vehicle or fuel cell vehicle, the electric compressor may be employed as a compressor 10. For example, the electric compressor is driven by an electric motor controlled by a controller for the conditioning of the fuel cell. air, so that the discharge capacity of the electric compressor is adjusted by controlling the number of revolutions of the electric motor.

Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.

Claims (18)

  A refrigerant cycle device comprising: a compressor (10) for sucking refrigerant and compressing the refrigerant to have a pressure above a critical refrigerant pressure; a radiator (12) for cooling the discharged refrigerant; from the compressor (10), a decompression means (13) for decompressing the refrigerant from the refrigerant outlet side of the radiator (12), an evaporator (14) for evaporating the low pressure refrigerant decompressed by the means decompression device (13), and a vapor / liquid separator (15) arranged on the refrigerant suction side of the compressor (10), for separating the refrigerant circulating from the evaporator (14) into a liquid phase refrigerant and a vapor phase refrigerant for storing therein the liquid phase refrigerant, where the internal volume of the low pressure side (VL) is the omme (Vacc + Veva) of the internal volume (Vacc) of the vapor / liquid separator (15) and of the internal volume (Veva) of the evaporator (14), and when the internal volume ratio of the vapor / liquid separator ( Racc) is the ratio (Vacc / VL) of the internal volume (Vacc) of the vapor / liquid separator (15) to the internal volume of the low pressure side (VL), the internal volume ratio of the vapor / liquid separator ( Racc) is set in a range of 0.18 or more. 30   The refrigerant cycle device according to claim 1, wherein the internal volume ratio of vapor / liquid separator (Racc) is set in a range of 0.44 or more.   Refrigerant cycle apparatus according to claim 1 or 2, wherein the internal volume ratio of vapor / liquid separator (Racc) is set in a range of 0.87 or less.   A refrigerant cycle apparatus according to claim 40, further comprising an internal heat exchanger (17) 2906016 44 for exchanging heat between the low pressure refrigerant on the refrigerant suction side of the compressor (10) and the high-pressure refrigerant on the upstream side of the decompression means (13), or when the internal volume ratio of the vapor-liquid separator (Racc) is the ratio (Vacc / VL) of the internal volume (Vacc) of the vapor separator / liquid (15) on the internal volume of the low pressure side (VL), and when the duct volume ratio of the high pressure side (Z) is the ratio (Vihe / Vgc) of the volume (Vihe) of a refrigerant duct on the high pressure side (17a) of the internal heat exchanger (17) through which the high pressure refrigerant flows over the internal volume (Vgc) of the radiator (12), the internal volume ratio of vapor / liquid separator (Race) is established in the beach 0.39Z + 0.18.   The refrigerant cycle device according to claim 4, wherein the internal volume ratio of vapor / liquid separator (Racc) is set in the range Racc? 0.45Z + 0.44.   The refrigerant cycle device according to claim 4 or 5, wherein the internal volume ratio of vapor / liquid separator (Racc) is set in the range of Racc S 0.22Z + 0.87.   The refrigerant cycle device according to any one of claims 4 to 6, wherein the high pressure side (Z) pipe volume ratio is set in a range of not less than 0.05 and higher. at 0.40.   The refrigerant cycle device according to any one of claims 1 to 3, wherein the internal volume (Vacc) of the vapor / liquid separator (15) is set within a range defined by the following formula: Vacc ((pgc - pmax) Vgc + (peva - pmax) Veva) / (pmax - pacc) where Vgc is the internal volume of the radiator (12), Veva is the internal volume of the evaporator (14), 2906016 45 pgc is the average refrigerant density in the radiator (12) in a high-load cycle operation, peva is the average refrigerant density in the evaporator (14) in the high-load cycle operation, pacc is the density of medium refrigerant in the vapor / liquid separator (15) in the high-load cycle operation, and pmax is the target upper limit refrigerant density.   The refrigerant cycle device according to any of claims 1 to 3, further comprising an internal heat exchanger (17) having therein a low pressure side refrigerant conduit (17b) through which the low pressure refrigerant on the compressor refrigerant suction side (10) flows, and a high pressure side refrigerant line (17a) through which the high pressure refrigerant on the upstream side of the decompression means (13) circulates, internal heat exchanger (17) being adapted to exchange heat between the low pressure refrigerant flowing through the low pressure side refrigerant line (17b) and the high pressure refrigerant flowing through the refrigerant line on the side high pressure (17a), wherein the internal volume (Vacc) of the vapor / liquid separator (15) is set within a range defined by the following formula: Vacc ((pgc - pmax). c + (pihe - pmax) Vihe + (peva - pmax). Veva) / (pmax - pacc) where Vgc is the internal volume of the radiator (12), Vihe is the internal volume of the refrigerant line on the high pressure side ( 17a), Veva is the internal volume of the evaporator (14), pgc is the average coolant density in the radiator (12) in a high-load cycle operation, pihe is the average refrigerant density in the refrigerant duct on the high pressure side (17a) in the high-load cycle operation, peva is the average refrigerant density in the evaporator (14) in the high-load cycle operation, pacc is the density of medium refrigerant in the vapor / liquid separator (15) in the high-load cycle operation, and pmax is the target upper limit refrigerant density. 10   A refrigerant cycle device comprising: a compressor (10) for sucking refrigerant and compressing the refrigerant to have a pressure above a critical refrigerant pressure; a radiator (12) for cooling the discharged refrigerant; from the compressor (10), a decompression means (13) for decompressing refrigerant from the refrigerant output side of the radiator (12), an evaporator (14) for evaporating the low pressure refrigerant decompressed by the means apparatus (13), a vapor / liquid separator (15) disposed on the refrigerant suction side of the compressor (10), for separating refrigerant circulating from the evaporator (14) to a liquid phase refrigerant and a vapor phase refrigerant 25 for storing therein the refrigerant in the liquid phase, and an internal heat exchanger (17) for exchanging heat. r between the low pressure refrigerant on the refrigerant suction side of the compressor (10) and the high pressure refrigerant on the upstream side of the decompression means (13), where when the internal volume of the low pressure side (VL) is the sum (Vacc + Veva) of the internal volume (Vacc) of the vapor / liquid separator (15) and the internal volume (Veva) of the evaporator (14), when the internal volume ratio of the vapor / liquid separator (Racc ) is the ratio (Vacc / VL) of the internal volume (Vacc) of the vapor / liquid separator (15) to the internal volume of the low pressure side (VL) and when the volume ratio of the conduit of the high pressure side (Z) is the ratio (Vihe / Vgc) of the volume (Vihe) of the refrigerant line on the high pressure side (17a) of the internal heat exchanger (17) through which the high-pressure refrigerant circulates on the internal volume ( Vgc) of the radiator (12), the internal volume ratio of vapor separator / liquid (Racc) is set in the range Racc? 0,, 392 + 0.18.   11. Device to. Refrigerant cycle according to claim 10, wherein the internal volume ratio of vapor / liquid separator (Racc) is set in the range of Racc> _ 0.45Z + 0.44.   Refrigerant cycle device according to claim 10 or 11, wherein the internal volume ratio of vapor / liquid separator (Racc) is set in the range Racc <0.22Z + 0.87.   The refrigerant cycle device according to any of claims 10 to 12, wherein the high pressure side (Z) pipe volume ratio is set in a range of not less than 0.05 and higher. at 0.40. 20   A refrigerant cycle apparatus comprising: a compressor (10) for sucking refrigerant and compressing the refrigerant to have a pressure above a critical refrigerant pressure; a radiator (12) for cooling the discharged refrigerant; from the compressor (10), a decompression means (13) for decompressing coolant from the radiator output side (12), an evaporator (14) for evaporating the low pressure refrigerant decompressed by the decompression means (13), and a vapor / liquid separator (15) disposed on the refrigerant suction side of the compressor (10), for separating the refrigerant flowing from the evaporator (14) into a liquid phase refrigerant and into a liquid refrigerant. vapor phase refrigerant for storing therein the liquid phase refrigerant, wherein the internal volume (Vacc) of the vapor / liquid separator (15) is set in a e range defined by the following formula: Vacc ((pgc - pmax). Vgc + (peva -pmax). Veva) / 40 (pmax - pacc) where Vgc is the internal volume of the radiator (12), Veva is the internal volume of the evaporator (14), pgc is the average refrigerant density in the radiator (12) in high load cycle operation, 5 peva is the average refrigerant density in the evaporator (14) in the high load cycle operation, pacc is the average refrigerant density in the vapor separator / liquid (15) in the high load cycle operation, and pmax is the target high limit refrigerant density.   A refrigerant cycle device comprising: a compressor (10) for sucking refrigerant and compressing the refrigerant to have a pressure above a critical refrigerant pressure; a radiator (12) for cooling the discharged refrigerant; from the compressor (10), a decompression means (13) for decompressing refrigerant from the radiator output side (12), an evaporator (14) for evaporating the low pressure refrigerant decompressed by the decompression means (13), a vapor / liquid separator (15) disposed on the refrigerant suction side of the compressor (10), for separating refrigerant circulating from the evaporator (14) to a liquid phase refrigerant and a vapor phase refrigerant for storing therein the liquid phase refrigerant, and an internal heat exchanger (17) having therein a refrigerant conduit therein and on the low pressure side (17b) through which the low pressure refrigerant on the refrigerant suction side of the compressor (10) flows and a refrigerant line on the high pressure side (17a) through which the high pressure refrigerant on the upstream of the decompression means (13) flows, the internal heat exchanger (17) being designed to exchange heat between the low pressure refrigerant flowing through the low pressure side refrigerant line (17b) and the refrigerant high pressure 2906016 49 flowing through the refrigerant line on the high pressure side (17a), where the internal volume (Vacc) of the vapor / liquid separator (15) is set within a range defined by the following formula: Vacc (( pgc pmax). Vgc + (pihe - pmax). Vihe + (peva - pmax). Veva) / (pmax - pacc) where Vgc is the internal volume of the radiator (12), Vihe is the internal volume of the refrigerant line on the high pressure side (17a), Veva is the internal volume of the evaporator (14) , gcg is the average refrigerant density in the radiator (12) in a high load cycle operation, where is the average refrigerant density in the high pressure side refrigerant line (17a) in the cycle operation at high load, peva is the average refrigerant density in the evaporator (14) in the high load cycle operation, pacc is the average refrigerant density in the vapor / liquid separator (15) in operation of high load cycle, and pmax is the target upper limit refrigerant density. 25   The refrigerant cycle device of claim 15, further comprising: a first refrigerant line (21) disposed between the refrigerant discharge side of the compressor (10) and the radiator refrigerant inlet side (12), a second refrigerant line (22) disposed between the radiator coolant outlet side (12) and the refrigerant inlet side of the high pressure side conduit (17a), a third refrigerant line (23) disposed between the refrigerant outlet side of the high pressure side conduit (17a) and the refrigerant inlet side of the decompression means (13), a fourth refrigerant line (24) disposed between the refrigerant outlet side of the decompression means (13) and the inlet side evaporator refrigerant (14), a fifth refrigerant line (25) disposed between the refrigerant outlet side of the evaporator (14) and the the refrigerant inlet side of the vapor / liquid separator (15), and between the refrigerant outlet side of the vapor / liquid separator (15) and the refrigerant inlet side of the low pressure side conduit (17b), and a sixth a refrigerant line (26) disposed between the refrigerant outlet side of the low pressure side duct (17b) and the refrigerant suction side of the compressor (10), wherein the internal volume setting range (Vacc) of the refrigerant suction separator (10); vapor / liquid (15) is calculated, through the use of the internal volume (V'gc) and the average coolant density (p'gc) of the radiator (12) corrected by the following formula, to the place of the internal volume (Vgc) and the average refrigerant density (gcg) of the radiator (12), through the use of the internal volume (V'ihe) and the average refrigerant density (p. ihe) of the refrigerant line on the high pressure side (17a) c orrected by the following formula, in place of the internal volume (Vihe) and the average refrigerant density (pihe) of the refrigerant conduit on the high pressure side (17a), and through the use of the internal volume (V'eva) and the average refrigerant density (p'eva) of the evaporator (14) corrected by the following formula, in place of the internal volume (Veva) and the average refrigerant density ( peva) of the evaporator (14), V'gc = Vgc + Vdpipe + Vhpipe p'gc = (pgc. Vgc + pdpipe. Vdpipe + phpipe. Vhpipe) / V'gc 30 V'ihe = Vihe + Vcpipe p'ihe = (pihe, Vihe + pcpipe, Vcpipe) / V'ihe V'eva = Vevain + Veva + Vlpipe + Vihel + Vspipe + Vcomp p'evLa = (Vevain + peva, Veva + plpipe, Vlpipe + pihel, Vihel + pspipe, Vspipe + Vompomp comp) / V'eva 35 where Vdpipe is the internal volume of the first refrigerant pipe (21), Vhpipe is the volume internal of the second refrigerant pipe (22), Vcpipe is the internal volume of the third refrigerant pipe (23), 2906016 51 Vevain is the internal volume of the fourth refrigerant pipe (24), Vipipe is the internal volume of the fifth refrigerant line (25), 5 Vihel is the internal volume of the low pressure side duct (17b), Vspipe is the internal volume of the sixth refrigerant duct (26), Vcomp is the internal volume of the compressor (10) , 10 pdpipe is the average refrigerant density in the first refrigerant line (21) in a cycle operation at high load, phpipe is the average refrigerant density in the second refrigerant line (22) in the high-load cycle operation, pcpipe is the average refrigerant density in the third refrigerant line (23) in the High-load cycle operation, e.g., the average refrigerant density in the fourth refrigerant line (24) in the high-load cycle operation, is the highest. average refrigerant density in the fifth refrigerant line (25) in the high-load cycle operation, 25 pihel is the average refrigerant density in the low-pressure side conduit (17b) in the high-load cycle operation pspipe is the average refrigerant density in the sixth refrigerant line (26) in the high-load cycle operation, and pcomp is the average refrigerant density in the compressor (10) in the load cycle operation high. 35   Refrigerant cycle apparatus according to any one of claims 8, 9, 14 to 16, wherein the target upper limit refrigerant density pmax is the refrigerant density at 60 C and 11 MPa. 2906016 52   The refrigerant cycle device of any one of claims 8, 9, 14 to 16, wherein the target upper limit refrigerant density pmax is the refrigerant density at 60 C and 10.5 MPa.