JP5209412B2 - Vapor compression refrigeration cycle - Google Patents

Description

  The present invention relates to a vapor compression refrigeration cycle, and particularly to a vapor compression refrigeration cycle suitable for a vehicle air conditioner having a refrigeration cycle using carbon dioxide, which is a natural refrigerant.

  In the case of a vapor compression refrigeration cycle in a vehicle air conditioner, when carbon dioxide, which is a natural refrigerant, is used as the refrigerant, the valve opening of the expansion device is controlled by an external control signal. One that adjusts the pressure of the high-pressure side line is known (for example, Patent Document 1).

  In such a refrigeration cycle, the high pressure side pressure at which the coefficient of performance (COP) of the refrigeration cycle is optimal is calculated by referring to the high pressure side refrigerant temperature of the refrigeration cycle, and the high pressure side pressure is optimal. Thus, the valve opening degree of the expansion device is controlled.

In addition, there has been proposed a system in which the refrigeration cycle is operated efficiently by changing the passage cross-sectional area of the orifice in accordance with the pressure and temperature of the gas cooler outlet refrigerant. This is because the pressure and temperature of the refrigerant on the gas cooler outlet side are controlled along the optimal control line obtained from the refrigerant temperature on the gas cooler outlet side and the pressure that maximizes the coefficient of performance, and carbon dioxide was used. It enables efficient operation of the refrigeration cycle.
Japanese Patent Laid-Open No. 7-294033

  As described above, the method of controlling the electrically controlled expansion mechanism so as to obtain the optimum high-pressure side pressure calculated by referring to the temperature of the refrigerant at the gas cooler outlet, and the passage cross-sectional area of the orifice depends on the pressure and temperature. A variable mechanical expansion mechanism has been proposed. The former detects the refrigerant temperature and pressure at the gas cooler outlet, and controls the electric expansion valve according to the detected amount, so that the device becomes complicated and large, the control method becomes complicated, and the cost increases. Has been. The latter makes the passage cross-sectional area of the orifice variable according to the gas cooler outlet refrigerant temperature and pressure, and because the gas cooler outlet refrigerant temperature is sensed, the piping connection of the refrigeration cycle becomes complicated, and there is a concern that the number of fastening parts will increase. Costs are also expected to rise. In general, a vapor compression refrigeration cycle using carbon dioxide includes an internal heat exchanger for exchanging heat between a high-pressure side refrigerant and a low-pressure side refrigerant. For this reason, the refrigerant that has flowed out of the gas cooler is circulated through the internal heat exchanger and then flows into the expansion mechanism. As a result, after detecting the refrigerant at the outlet of the gas cooler, the internal heat exchanger is circulated again and then flows into the expansion mechanism. Therefore, in the mechanical expansion mechanism described above, compared to the advantages in terms of application It is thought that there are major drawbacks.

  FIG. 1 shows the relationship between the refrigerant pressure and the coefficient of performance (COP) of the refrigeration cycle with respect to the gas cooler outlet refrigerant temperature. From FIG. 1, when the gas cooler outlet refrigerant temperature is equal to or lower than the critical temperature (about 31 ° C.), the coefficient of performance improves as the value of the high-pressure side refrigerant pressure decreases. In addition, there is a certain high-pressure refrigerant pressure (location on the dotted line in FIG. 1) at which the coefficient of performance is maximum above the critical temperature, and the coefficient of performance is maximized as the gas cooler outlet refrigerant temperature rises. It can be seen that the pressure rises more. In addition, when the gas cooler outlet refrigerant temperature exceeds a certain predetermined temperature (about 40 ° C.), it can be confirmed that the superiority or inferiority of the coefficient of performance due to the change in the high-pressure side pressure becomes small. From these things, it is thought that it is important to positively control the high-pressure side refrigerant pressure (the pressure control range is about 8 to 10 MPa) when the gas cooler outlet refrigerant temperature is in the range of about 30 ° C to 40 ° C.

  However, in the above temperature range, although the coefficient of performance improves if it can be controlled to the high-pressure side refrigerant pressure at which the coefficient of performance is maximized, when the control is performed at a pressure lower than the optimum high-pressure side refrigerant pressure, the coefficient of performance of It can be seen that the decrease is significant. Therefore, in the method of controlling the high-pressure side refrigerant pressure by the gas cooler outlet refrigerant temperature, the effect can be expected in a specific temperature range (a range of about 30 ° C. to 40 ° C.) and at that time It is considered that the high-pressure side control pressure needs to be controlled above the optimum pressure (for example, the region A shown in FIG. 1).

  Further, since the expansion mechanism as described above is an expansion mechanism and a control method for the purpose of controlling the high-pressure side pressure to the optimum high pressure as a whole, the complexity of the apparatus (refrigeration cycle) and the difficulty of control are limited. There are major issues such as high costs. Therefore, it is considered that there is a trade-off between the effect of improving the coefficient of performance by detecting the refrigerant temperature at the gas cooler outlet and controlling the refrigerant pressure on the high pressure side, the simplicity of the piping configuration of the refrigeration cycle, the simplicity of control, etc. . Therefore, it is desired to develop an expansion mechanism that simplifies the piping configuration of the refrigeration cycle and aims to improve the coefficient of performance.

  In response to such a request, the application is still unpublished, but the applicant has previously proposed an expansion mechanism that can control the differential pressure before and after passing through the expansion mechanism according to the refrigerant pressure. In addition, an expansion mechanism that can change the characteristics of differential pressure control before and after passing through the expansion mechanism is also proposed according to the refrigerant temperature after passing through the expansion mechanism (Japanese Patent Application No. 2007-115368). Specifically, in the expansion mechanism that controls the differential pressure before and after passage through the expansion mechanism according to the refrigerant pressure, the minimum refrigerant passage diameter and differential pressure control characteristics that can improve the coefficient of performance of the vapor compression refrigeration cycle should be set Thus, an expansion mechanism capable of achieving an improvement in the coefficient of performance as well as a simple refrigeration cycle was obtained.

  However, when the above expansion mechanism was examined under various conditions, it became clear that the following problems remained. In other words, it has been found that the variation in the temperature distribution of the outlet air temperature of the evaporator increases under the condition that the heat load is small in the refrigeration cycle using this expansion mechanism. This is because the refrigerant flowing through the expansion mechanism and flowing into the evaporator is insufficient, so that the refrigerant cannot properly flow inside the evaporator, and the temperature distribution of the outlet air temperature of the evaporator is uneven. It is done. That is, it is considered that the refrigerant has become insufficient. Further, it has been confirmed by the present inventors that such a state where the refrigerant is insufficient is solved by increasing the minimum diameter of the refrigerant passage of the expansion mechanism. However, as described above, since the minimum diameter of the refrigerant flow path of the expansion mechanism is determined with the aim of improving the coefficient of performance of the vapor compression refrigeration cycle, increasing the minimum diameter of the refrigerant flow path reduces the coefficient of performance. It will be connected. In addition, as described above, in the specification of the expansion mechanism that aims to improve the coefficient of performance, the refrigerant (passing refrigerant amount) becomes insufficient under low load conditions. Furthermore, since it is assumed that it is difficult to start the refrigeration cycle at a low load due to a decrease in low pressure, there is a concern that the function as the vapor compression refrigeration cycle may be impaired.

  Accordingly, an object of the present invention is to make it possible to optimally control the differential pressure before and after passing through the expansion mechanism in accordance with the pressure of the refrigerant, and to detect the load state based on the temperature of the refrigerant passing through the expansion mechanism. Vapor compression type refrigeration that can change the differential pressure control state before and after passing through the expansion mechanism according to the temperature of the compressor, and that can optimally control the load state, especially the problem of refrigerant shortage and start-up difficulty at low loads To provide a cycle.

  In order to solve the above-described problems, a vapor compression refrigeration cycle according to the present invention includes an expansion mechanism that adiabatically expands a refrigerant circulating in the refrigeration cycle during a vapor compression refrigeration cycle having a supercritical operating region of the refrigerant. Differential pressure type expansion means capable of adjusting the amount of refrigerant passing through the expansion mechanism in accordance with the differential pressure between the inlet side refrigerant pressure and the outlet side refrigerant pressure of the expansion mechanism. The expansion means includes a differential pressure valve that starts valve opening when the differential pressure becomes equal to or higher than a preset valve opening start pressure, and increases the valve opening amount as the differential pressure increases. The differential pressure valve includes a refrigerant communication path that extends through the differential pressure valve and allows the refrigerant that has flowed into the expansion mechanism to constantly pass through the differential pressure valve and adiabatically expand, and the closed position of the differential pressure valve is The tip of the differential pressure valve is locked to the locking part of the expansion mechanism housing. In addition, a valve tip portion flow passage through which refrigerant can always flow is formed at the tip portion of the differential pressure valve other than the locking portion of the casing of the expansion mechanism. Is configured so that the flow path cross-sectional area can be varied according to the temperature of the refrigerant flowing in by the temperature correction means including a movable body that can be displaced according to the temperature of the refrigerant flowing into the expansion mechanism. It consists of what is characterized by being.

  In such a vapor compression refrigeration cycle according to the present invention, the amount of refrigerant passing through the expansion mechanism is adjusted by the differential pressure expansion means. The refrigerant amount is determined by the inlet side refrigerant pressure and the outlet side of the expansion mechanism. When the differential pressure from the refrigerant pressure (differential pressure before and after passing through the expansion mechanism) is equal to or higher than a preset valve opening start pressure, valve opening is started, and the valve opening amount is increased as the differential pressure increases. It is controlled by the operation of the pressure valve and the operation of the movable body of the temperature correction means that can be displaced according to the temperature of the refrigerant flowing into the expansion mechanism. That is, the refrigerant flow path cross-sectional area for allowing the refrigerant to pass through the differential pressure valve portion is equal to the flow path cross-sectional area of the refrigerant communication path (fixed orifice) through which the refrigerant formed in the differential pressure valve always passes through the differential pressure valve. The valve cross-sectional area according to the valve opening amount from the valve closing position (the position where the tip of the differential pressure valve is locked to the locking portion of the housing of the expansion mechanism), and the tip of the differential pressure valve other than the locking portion The flow path cross-sectional area corresponding to the valve opening amount of the differential pressure valve is determined by the refrigerant expansion mechanism. When the differential pressure before and after passage becomes equal to or higher than the valve opening start pressure, the differential pressure increases as the differential pressure increases. It is variable by. In other words, the valve opening amount of the differential pressure valve is appropriately variably controlled according to the differential pressure before and after passing through the expansion mechanism, and the flow path cross-sectional area corresponding to the valve opening amount of the differential pressure valve is in accordance with the temperature of the refrigerant. Temperature correction control is performed to a more optimal flow path cross-sectional area by the displacement of the movable body. Therefore, along with appropriate control of the differential pressure before and after passing through the expansion mechanism, it is possible to detect the load at that time based on the refrigerant temperature and to make corrections according to the load, in particular, to increase the refrigerant flow rate at low loads. It is possible to ensure reliable start-up during operation and low load.

  In the vapor compression refrigeration cycle according to the present invention, when the differential pressure valve is closed, if the temperature of the inflowing refrigerant is equal to or higher than a predetermined value, the valve tip portion flow path is disconnected. It is preferable that the area is maintained at a predetermined flow path cross-sectional area. That is, when the differential pressure valve is closed, the flow passage cross-sectional area of the valve tip portion flow passage is determined by the position of the movable body at that time, but when the refrigerant temperature is equal to or higher than a predetermined value. Is configured such that the position of the movable body is set to a predetermined fixed position, whereby the flow path cross-sectional area of the valve tip portion flow path is maintained at a predetermined flow path cross-sectional area determined in advance. It is preferable. By adopting such a configuration, when the temperature of the refrigerant is lower than a predetermined value, the movable body is displaced from a predetermined fixed position, and the flow path cross-sectional area of the valve tip portion flow path is expanded, thereby It becomes possible to increase the refrigerant flow rate at the time of low load. In order to position the movable body at a predetermined fixed position, for example, the movable body may be locked to an appropriate part of the housing of the expansion mechanism.

  Therefore, it is preferable that the movable body of the temperature correcting means is displaced so that the flow passage cross-sectional area of the valve tip portion flow passage becomes larger as the temperature of the refrigerant flowing in becomes lower. This is to ensure both efficient operation of the refrigeration cycle particularly at low loads and reliable start-up at low loads.

  The flow path cross-sectional area of the valve tip flow path when the temperature of the inflowing refrigerant is lower than the predetermined value set in advance is 0.5 mm or more and 0.8 mm or less in the flow path equivalent diameter. It is preferable to set within the range. However, since this range is derived as an appropriate range from the results in a certain experimental system, it is not restricted to this range depending on the specifications of the vapor compression refrigeration cycle.

  Further, in the above, the movable body of the temperature correction means is configured such that the flow passage cross-sectional area of the valve tip portion flow passage becomes the flow passage cross-sectional area of the refrigerant communication passage of the differential pressure valve as the temperature of the refrigerant flowing in decreases. It is preferable to be displaced so as to be larger than that. The refrigeration cycle can be started more reliably at low loads by being displaced so as to be larger than the flow path cross-sectional area of the refrigerant communication passage (fixed orifice) of the differential pressure valve.

  The vapor compression refrigeration cycle according to the present invention is particularly suitable for use as a refrigeration cycle for a vehicle air conditioner, and is particularly suitable when the refrigerant used is made of carbon dioxide, which is a natural refrigerant. is there.

  According to the vapor compression refrigeration cycle according to the present invention, in particular, in a vehicle air conditioner that uses carbon dioxide, which is a natural refrigerant, as a refrigerant in the vapor compression refrigeration cycle, the difference between before and after passing through the expansion mechanism according to the refrigerant pressure. The pressure can be appropriately controlled, and the control state can be optimally corrected according to the temperature of the refrigerant, so that the optimum design of the differential pressure type expansion means can be realized. Efficient operation and start-up stability of the cycle can be ensured.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 2 shows an entire mechanical component when a vapor compression refrigeration cycle using carbon dioxide, which is a natural refrigerant, is incorporated into a vehicle air conditioner according to an embodiment of the present invention. A ventilation circuit and a refrigeration circuit (refrigeration cycle) are provided. In the refrigeration cycle, a fixed capacity type driven by the driving of the belt 12 via the pulleys 2 and 3 by the engine 1 of the vehicle as a driving source (however, another driving source such as an electric motor is also possible) Variable capacity compressor 4, high pressure side pressure detecting means 5 for detecting the pressure of the high pressure refrigerant discharged from the compressor 4, and heat radiation for cooling the refrigerant by heat exchange between the high pressure refrigerant from the compressor 4 and external air A heat exchanger 6 (gas cooler), a radiator cooling fan 7, an internal heat exchanger 8 for exchanging heat between the high-pressure refrigerant flowing out of the radiator 6 and the low-pressure refrigerant flowing out of the gas-liquid separator 11 (accumulator); An expansion mechanism 9 for adiabatically expanding the refrigerant sent from the radiator 6 through the internal heat exchanger 8 is provided. In the present invention, the expansion mechanism 9 includes an inlet side refrigerant pressure and an outlet side refrigerant pressure of the expansion mechanism. Depending on the differential pressure And a differential pressure type expansion means capable of adjusting the amount of refrigerant passing through the expansion mechanism Te. The refrigerant from the expansion mechanism 9 is sent to the evaporator 10 to cool the conditioned air, and the refrigerant that has flowed out of the evaporator 10 is separated into gas and liquid by the gas-liquid separator 11 so that the liquid refrigerant is stored and the gas refrigerant is stored. The discharged refrigerant is sent to the compressor 4 through the internal heat exchanger 8 and is compressed again. Thus, the refrigeration cycle 13 is configured.

  The evaporator 10 is arrange | positioned in the ventilation duct 14 which sends an air conditioned wind into a vehicle interior. Air is introduced into the ventilation duct 14 from the outside air introduction port 15 and the inside air introduction port 16 via the inside / outside air switching damper 17, and the operation of the inside / outside air switching damper 17 is controlled by the inside / outside air switching damper actuator 18. The introduced air is sucked by the blower fan 19 and is pumped toward the evaporator 10 on the downstream side. An evaporator outlet air temperature sensor 20 is provided on the outlet side of the evaporator 10, and a heater core 21 as a heater is provided on the downstream side of the evaporator 10. The ratio of the air passing through the heater core 21 and the bypassing air is adjusted by the air mix damper 22, and the opening degree of the air mix damper 22 is controlled by the air mix damper actuator 23. The temperature-adjusted air is blown out from the outlets 27, 28, 29 through the dampers 24, 25, 26 toward the vehicle interior.

  Reference numeral 31 denotes an air conditioning control device. The air conditioning control device 31 includes an outside air temperature signal from the outside air temperature sensor 32, a solar radiation amount signal from the solar radiation sensor 33, a vehicle interior temperature signal from the vehicle interior temperature sensor 34, and a high pressure side. The high pressure side refrigerant pressure signal 35 of the pressure detection means 5 and the evaporator outlet air temperature signal from the evaporator outlet air temperature sensor 20 are input. From the air conditioning controller 31, a clutch control signal 37 is sent to the clutch controller 36 that controls the drive of the compressor 4, a compressor capacity control signal 38 is sent to the compressor 4, and an air mix damper control signal 39 is sent to the air mix damper actuator 23. The inside / outside air switching damper control signal 40 is output to the inside / outside air switching damper actuator 18.

  3 shows an example of a basic form (form which is a premise of the present invention) of an expansion mechanism 41 provided with a differential pressure type expansion means (the arrow indicates the flow direction of the refrigerant. The same applies to the following figures. is there.). However, FIG. 3 is a conceptual diagram of the mechanism, and is not limited to the illustrated structure. The differential pressure type expansion mechanism 41 in FIG. 3 has a fixed orifice portion 42 as a refrigerant communication path through which refrigerant always flows, and the inlet side refrigerant pressure of the expansion mechanism 41 and the expansion mechanism refrigerant outlet at the expansion mechanism refrigerant inlet 43. The amount of refrigerant passing through the expansion mechanism 41 can be adjusted according to the pressure difference between the outlet side refrigerant pressure of the expansion mechanism 41 at 44 and the differential pressure valve 45 is opened as the differential pressure increases. The differential pressure valve 45 is urged in the valve closing direction by a spring 46.

  The refrigerant that has flowed in from the upstream side of the differential pressure type expansion mechanism 41 passes through the fixed orifice portion 42 as a refrigerant communication path provided in the differential pressure valve 45 and is sent to the evaporator 10 from the expansion mechanism refrigerant outlet 44. The differential pressure valve 45 having the fixed orifice portion 42 receives pressure from the refrigerant from the upstream side, and the pressure acts as a force in the valve opening direction on the spring 46 connected to the differential pressure valve 45. The spring 46 acts as a force toward the upstream side, that is, a force in the valve closing direction. When the force relationship in the valve closing direction is stronger than the force in the valve opening direction, the differential pressure valve 45 having the fixed orifice portion 42 does not open, and the fixed orifice is used as the refrigerant channel cross-sectional area. The expansion mechanism has the flow path cross-sectional area of the portion 42. On the other hand, when the force in the valve opening direction is stronger than the force in the valve closing direction, the differential pressure valve 45 is opened, and the housing of the differential pressure valve 45 and the expansion mechanism 41 is added to the cross-sectional area of the fixed orifice portion 42. Thus, the expansion mechanism has a refrigerant flow path cross-sectional area to which a gap is added. According to such an operating principle, the refrigerant flow passage cross-sectional area is changed by the differential pressure across the fixed orifice portion 42, and the differential pressure across the front or back side or the high-pressure side pressure is controlled.

  In the present invention, a temperature correction mechanism as a temperature correction means as described below is added to the differential pressure type expansion mechanism 41 according to the basic form as described above. FIG. 4 shows the differential pressure type expansion mechanism 51 according to the first embodiment to which a temperature correction mechanism is added. The fixed orifice portion 42 as the refrigerant communication path, the expansion mechanism refrigerant inlet 43, the expansion mechanism refrigerant outlet 44, and the difference Since the structures of the pressure valve 45 and the spring 46 are the same as or the same as those shown in FIG. 3, the description thereof is omitted by giving the same reference numerals as those shown in FIG. In the first embodiment, the valve closing position of the differential pressure valve 45 is determined by the distal end portion 45a of the differential pressure valve 45 being locked to the locking portion 52 of the housing of the expansion mechanism. A valve tip portion flow path 53 through which refrigerant can always flow is formed at a tip portion 45b of the differential pressure valve 45 corresponding to a portion other than the locking portion 52 of the casing of the expansion mechanism. Reference numeral 53 is a temperature correction means having a movable body 54 that can be displaced according to the temperature of the refrigerant flowing into the expansion mechanism 51, and the flow path cross-sectional area is varied according to the temperature of the flowing refrigerant. It is configured as follows. In this embodiment, the movable body 54 is biased by a spring 55 made of a shape memory alloy. When the temperature of the spring 55 made of a shape memory alloy is lower than a predetermined value (the temperature of the refrigerant flowing in), the spring length is shortened. It is displaced in the right direction. In this embodiment, the movable body 54 is locked to the locking portion 52 and the locking portion 56 of the casing of the expansion mechanism different from the locking portion 52 before displacement. When the valve is closed, the flow path cross-sectional area of the valve front end flow path 53 is maintained at a predetermined flow path cross-sectional area. However, as the temperature of the refrigerant flowing in becomes lower than the predetermined value, the movable body 54 is displaced in the right direction in FIG. 4, and the flow path cross-sectional area of the valve tip end flow path 53 becomes the predetermined value. It is increased from the flow path cross-sectional area. This increase in the flow passage cross-sectional area of the valve tip portion flow passage 53 makes it possible to increase the refrigerant flow rate particularly at low loads. In addition to efficient operation of the refrigeration cycle by the differential pressure valve 45 described above, Secure start-up can be ensured. In addition, the said movable body 54 can be formed in the shape provided with the tongue part 57 with respect to the cyclic | annular body as a more concrete shape, for example, as shown in FIG.

  FIG. 6 shows a differential pressure type expansion mechanism 61 according to the second embodiment to which a temperature correction mechanism is added. The fixed orifice portion 42 as the refrigerant communication path, the expansion mechanism refrigerant inlet 43, the expansion mechanism refrigerant outlet 44, and the difference Since the structures of the pressure valve 45 and the spring 46 are the same as or the same as those shown in FIG. 3, the description thereof is omitted by giving the same reference numerals as those shown in FIG. Also in the second embodiment, the valve closing position of the differential pressure valve 45 is determined by the front end portion 45a of the differential pressure valve 45 being locked to the locking portion 52 of the housing of the expansion mechanism. A valve tip portion flow path 62 through which refrigerant can always flow is formed at a tip portion 45b of the differential pressure valve 45 corresponding to a portion other than the locking portion 52 of the casing of the expansion mechanism. Reference numeral 62 denotes a temperature correction means including a movable body 63 that can be displaced according to the temperature of the refrigerant flowing into the expansion mechanism 61, and the flow path cross-sectional area is varied according to the temperature of the flowing refrigerant. It is configured as follows. In this embodiment, as shown in FIG. 7, the movable body 63 is formed in a shape in which an annular flange portion 64 is provided on the outer periphery of the central portion in the longitudinal direction of the cylindrical body. A tongue 65 similar to that shown in FIG. 5 is provided. On each side of the annular flange portion 64, springs 66 and 67 are arranged, and the movable body 63 is determined at a position where the spring forces of both the springs 66 and 67 are balanced. In the present embodiment, at least one of the springs 66 and 67 is configured as a spring made of a shape memory alloy, and when the temperature of the refrigerant flowing in becomes lower than a predetermined value, the spring made of a shape memory alloy The movable body 63 is displaced in the right direction in FIG. Due to the displacement of the movable body 63, the flow path cross-sectional area of the valve tip end flow path 62 is increased from a predetermined flow path cross-sectional area. This increase in the flow passage cross-sectional area of the valve tip portion flow passage 62 makes it possible to increase the refrigerant flow rate particularly at low loads. In addition to the efficient operation of the refrigeration cycle by the differential pressure valve 45 described above, Secure start-up can be ensured.

  In the embodiment in which the temperature correction mechanism having the movable bodies 54 and 63 is added as described above, the comparative example without the movable bodies 54 and 63 (that is, compared with the differential pressure type expansion mechanism 41 shown in FIG. The horizontal axis in Fig. 8 indicates the differential pressure across the fixed orifice 42, and the vertical axis indicates the channel equivalent diameter of the channel cross-sectional area of the valve tip channel. As shown in the drawing, particularly at the time of low load before the differential pressure valve 45 is opened, the flow passage cross-sectional area of the valve tip portion flow passage is appropriately increased according to the refrigerant temperature to facilitate the flow of the refrigerant, The flow rate of the refrigerant sufficient for starting the refrigeration cycle can be ensured, and the flow passage cross-sectional area of the valve tip flow passage is within the range of 0.5 to 0.8 mm at the equivalent flow passage diameter as shown in the figure. Preferably there is.

  The structure of the differential pressure type expansion mechanism in the vapor compression refrigeration cycle according to the present invention can be applied to any vapor compression refrigeration cycle, and is particularly suitable for a refrigeration cycle of a vehicle air conditioner using a carbon dioxide refrigerant. .

It is a relationship figure of the refrigerant | coolant pressure and the coefficient of performance (COP) of a refrigerating cycle regarding a gas cooler exit | outlet refrigerant | coolant temperature. It is an equipment distribution diagram of a vehicle air conditioner incorporating a vapor compression refrigeration cycle according to an embodiment of the present invention. It is a schematic sectional drawing which shows an example of the basic form of a differential pressure type expansion mechanism. It is a schematic sectional drawing of the differential pressure type | formula expansion mechanism which concerns on Example 1 of this invention. It is a perspective view of the movable body in FIG. It is a schematic sectional drawing of the differential pressure | voltage type expansion mechanism which concerns on Example 2 of this invention. It is a perspective view of the movable body in FIG. It is a characteristic view which shows an example of the action | operation in the Example of the differential pressure | voltage type expansion mechanism which added the temperature correction mechanism in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2, 3 Pulley 4 Compressor 5 High pressure side pressure detection means 6 Radiator (gas cooler)
7 Radiator Cooling Fan 8 Internal Heat Exchanger 9 Differential Pressure Type Expansion Mechanism 10 Evaporator 11 Gas-Liquid Separator (Accumulator)
12 Belt 13 Refrigeration cycle 14 Ventilation duct 15 Outside air inlet 16 Inside air inlet 17 Inside / outside air switching damper 18 Inside / outside air switching damper actuator 19 Blower fan 20 Evaporator outlet air temperature sensor 21 Heater core 22 Air mix damper 23 Air mix damper actuator 24 25, 26 Dampers 27, 28, 29 Air outlet 31 Air conditioning control device 32 Outside air temperature sensor 33 Solar radiation sensor 34 Car interior temperature sensor 35 High pressure side refrigerant pressure signal 36 Clutch controller 37 Clutch control signal 38 Compressor capacity control signal 39 Air mix damper Control signal 40 Inside / outside air switching damper control signals 41, 51, 61 Differential pressure type expansion mechanism 42 Fixed orifice part 43 as refrigerant communication passage Expansion mechanism refrigerant inlet 44 Expansion mechanism refrigerant outlet 45 Differential pressure valve 45a, 45b Tip of differential pressure valve 46 spring 52, 56 engaging portions 53 and 62 valve tip channel 54,63 movable member 55,66,67 spring (shape memory alloy spring)
57, 65 tongue 64 annular flange

Claims (7)

  During the vapor compression refrigeration cycle having the supercritical operating region of the refrigerant, the refrigerant circulating in the refrigeration cycle can be adiabatically expanded by the expansion mechanism, and the inlet side refrigerant pressure and the outlet side refrigerant pressure of the expansion mechanism Differential pressure type expansion means capable of adjusting the amount of refrigerant passing through the expansion mechanism according to the differential pressure, wherein the differential pressure type expansion means has the differential pressure equal to or higher than a preset valve opening start pressure. A differential pressure valve that starts valve opening and increases the valve opening amount as the differential pressure increases. The differential pressure valve extends through the differential pressure valve and flows into the expansion mechanism. Is provided with a refrigerant communication passage that can always pass through the differential pressure valve and adiabatically expand, and the closed position of the differential pressure valve is locked by the locking portion of the expansion mechanism housing at the tip of the differential pressure valve. And the locking portion of the housing of the expansion mechanism The tip portion of the outer differential pressure valve is formed with a valve tip passage that allows the refrigerant to always flow, and the valve tip passage can be displaced according to the temperature of the refrigerant flowing into the expansion mechanism. A vapor compression refrigeration cycle, characterized in that the flow path cross-sectional area is varied according to the temperature of the inflowing refrigerant by a temperature correction means including a movable body.   When the differential pressure valve is closed, if the temperature of the refrigerant flowing in is equal to or higher than a predetermined value, the flow path cross-sectional area of the valve tip end flow path is maintained at a predetermined flow path cross-sectional area. The vapor compression refrigeration cycle according to claim 1, wherein the vapor compression refrigeration cycle is configured to lean.   The movable body of the temperature correction means is displaced so that a flow passage cross-sectional area of the valve tip portion flow passage becomes larger as the temperature of the inflowing refrigerant becomes lower. Vapor compression refrigeration cycle.   The flow passage cross-sectional area of the valve tip portion flow passage when the temperature of the inflowing refrigerant becomes lower than the predetermined value is 0.5 mm or more and 0.8 mm or less in the flow passage equivalent diameter. The vapor compression refrigeration cycle according to claim 2 or 3, which is set within a range of.   In the movable body of the temperature correction means, the flow passage cross-sectional area of the valve tip portion flow passage becomes larger than the flow passage cross-sectional area of the refrigerant communication passage of the differential pressure valve as the temperature of the refrigerant flowing in becomes lower. The vapor compression refrigeration cycle according to claim 3 or 4, which is displaced as follows.   The vapor compression refrigeration cycle according to any one of claims 1 to 5, which is used as a refrigeration cycle for a vehicle air conditioner.   The vapor compression refrigeration cycle according to any one of claims 1 to 6, wherein the refrigerant used is made of carbon dioxide.

Images