JP2000346499A - Pressure control valve for vapor compression type refrigerating cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure control valve for preventing an excessive deformation of or damage to an elongating and contracting container and efficiently operating a vapor compression type cycle to operate in a supercritical region. SOLUTION: The pressure control valve 3 comprises a valve body 12 having a first valve port 13a and a second valve port 14a respectively formed at an upstream side space 7a side and a downstream side space 7b side of a refrigerant passage 7, an elongating and contracting container 17 provided in the body 12 and having a sealed space 17a formed therein to elongate or contract in response to a pressure difference in and out of the space 17a, a temperature sensitive cylinder 11 provided in the passage 7 near an outlet of a radiator to communicate with the container 17 through a tube member 10 to transfer a refrigerant temperature near the outlet of the radiator into the container 17, a valve 16 fixed to the container 17 to open the port 14a when the container 17 is displaced, and a check valve 15 provided in the body 12 to open the port 13a when an internal pressure of the space 7a becomes larger than that of the body 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pressure control valve for controlling the radiator outlet-side pressure of the vapor compression refrigeration cycle (high side pressure), in particular refrigerant in a supercritical range, such as carbon dioxide (CO ₂₎ The present invention relates to a pressure control valve suitable for use in a vapor compression refrigeration cycle used.

[0002]

2. Description of the Related Art In recent years, as one measure against CFCs in refrigerant used in a vapor compression refrigeration cycle, for example, Japanese Patent Publication No.
No. 18602, carbon dioxide (CO ₂ )
There has been proposed a vapor compression refrigeration cycle (hereinafter, abbreviated as CO ₂ cycle) using the same. The operation of this CO ₂ cycle is basically the same as the operation of a conventional vapor compression refrigeration cycle using Freon. That is, FIG.
As shown by ABCDA of O ₂ Mollier diagram), CO ₂ in a gaseous state is compressed by a compressor (AB),
This high-temperature compressed gaseous CO ₂ is cooled by a radiator (gas cooler) (BC). Then, the pressure is reduced by a pressure reducer (CD) to evaporate the CO ₂ in a gas-liquid two-phase state (DA), and the external fluid is cooled by removing latent heat of evaporation from an external fluid such as air. .

Meanwhile, since the critical temperature of CO ₂ is lower than the critical point temperature of about 31 ° C. and conventional flon, in summer or the like, higher than the critical point temperature CO ₂ temperature of CO ₂ at the radiator side turn into. In other words, CO
₂ does not condense (line BC does not intersect with saturated liquid line SL). The state of the radiator outlet side (C point), the discharge pressure of the compressor is determined by the CO ₂ temperature at the radiator outlet side, CO ₂ temperature at the radiator outlet side, the radiator of the heat radiation capacity The temperature at the radiator outlet cannot be substantially controlled, as determined by the outside air temperature (which is uncontrollable). Therefore, the state of the radiator outlet side (point C) can be controlled by controlling the compressor discharge pressure (radiator outlet side pressure). That is, when the outside air temperature is high in summer or the like, in order to secure a sufficient cooling capacity (enthalpy difference), as shown by EFGHE in FIG. High pressure is needed.

However, in order to increase the pressure on the outlet side of the radiator,
Must increase the compressor discharge pressure as described above.
The compression work of the compressor (enthalpy of the compression process)
The change amount ΔL) increases. Therefore, the evaporation process (D-
In the compression process (A),
-B) when the increase in the enthalpy change ΔL is large
Is CO_TwoCycle coefficient of performance (COP = ΔI / ΔL)
Worsens. Therefore, for example, CO at the radiator outlet side_Two Warm
Temperature at 40 ° C and CO at the radiator outlet side_Two Pressure and performance
A trial calculation of the relationship between the coefficients using FIG. 3 shows a solid line in FIG.
As the pressure P ₁(Approximately 10 MPa)
Is the largest. Similarly, CO at the radiator outlet side_Two Temperature
When the temperature is 30 ° C., as shown by the broken line in FIG.
P_Two(Approximately 8.0 MPa)
You.

[0005] As described above, CO _{2 at the} radiator outlet side is
The temperature and the pressure at which the coefficient of performance is maximized are calculated, and the result is depicted in FIG. 4, as indicated by the thick solid line η _max (hereinafter, optimal control line) in FIG. Therefore, in order to efficiently operate the CO ₂ cycle, a pressure control valve that controls the radiator outlet side pressure and the radiator outlet side CO ₂ temperature as indicated by an optimal control line η _max has been developed. (See, for example, Japanese Patent Application Laid-Open No. 9-264622).

[0006] This pressure control valve has ρ = 600 kg / m ³
The characteristic that the iso-density line of FIG. 2 is approximately similar to the optimum control line η _max is used. As shown in FIG. 6, a bellows 101 (or a diaphragm) is provided in the gas cooler outlet passage 100.
Stretch-death ρ = 450~950kg / m ³ of CO ₂ arranged telescopic container 102 enclosing, by fixing the valve body 103 to the expansion vessel 102 by, for example, the outlet passage 10
The valve body 103 is opened and closed by a pressure difference between a balance pressure in the telescopic container with respect to a gas temperature of 0 and a passage pressure. Thus, the outlet pressure of the radiator, after raised to a pressure along substantially on the optimum control line eta _max, open the valve port and an outlet side temperature of the radiator and the outlet pressure of the radiator, substantially Control is performed along the optimal control line η _max . In FIG. 6, reference numeral 104 denotes a valve port, and reference numeral 105 denotes a valve body provided inside the bellows 101.
3 shows a coil spring that urges 3 to close.

[0007]

By the way, in the conventional pressure control valve, for example, especially when the vapor compression refrigeration cycle is stopped or during low-capacity operation, the pressure outside the telescopic vessel, that is, the refrigerant passage pressure is small. Internal pressure is always high (about 7MPa at 30 ℃, 11MPa at 45 ℃)
The pressure difference between the inside and outside of the telescopic container becomes large, so that the bellows or the diaphragm is excessively deformed and the original elastic restoring force is reduced and the life is shortened.
There is a problem that there is a possibility of damage. If the strength of the bellows or the diaphragm is increased for the purpose of solving such a problem, the telescopic container does not expand and contract due to a small internal / external pressure difference, and the above-mentioned expected operation of the pressure control valve cannot be achieved.

The present invention has been made in view of the above-mentioned problems of the prior art, does not apply a large pressure difference between the inside and outside of the telescopic container, prevents the telescopic container from being excessively deformed or damaged, and also has a radiator. A pressure control valve for a vapor compression refrigeration cycle that controls the outlet pressure and the radiator exit side temperature substantially along an optimal control line to efficiently operate a vapor compression cycle operating in a supercritical region. It is intended to be.

[0009]

According to the present invention, there is provided a vapor compression refrigeration cycle comprising a refrigerant passage disposed in the middle of a refrigerant passage from a radiator to an evaporator and having a refrigerant temperature at an outlet of the radiator. A first valve port and a second valve port are formed on the upstream space side and the downstream space side of the refrigerant passage, respectively, in the pressure control valve that controls the pressure at the radiator outlet side to a target value in accordance with A valve body, a telescoping container provided in the inner space of the valve body in a manner displaceable in accordance with a pressure difference between the inside and outside of the internal sealed space, and a pipe provided in the refrigerant passage near an outlet of the radiator. A temperature-sensitive tube that is communicated with the telescopic container through a member and that conducts a refrigerant temperature near the outlet of the radiator into the telescopic container, and is fixed to the telescopic container, when the telescopic container is displaced. A valve for opening the second valve port, Provided in the main body, and a first valve open mouth check valve when the upstream-side space pressure becomes greater than the valve body pressure, the valve body,
In the telescopic container, the temperature-sensitive cylinder and the pipe member, the refrigerant gas is filled with the refrigerant from a saturated liquid density at 0 ° C. in a state where the valve and the check valve are closed. A high-pressure control valve for a vapor compression refrigeration cycle, wherein the high-pressure control valve is sealed at a density within a predetermined range up to a saturated liquid density at a critical point of the refrigerant.

In the pressure control valve of the present invention, when the operation of the cycle is stopped, the second valve port is closed by the valve of the telescopic container. The first valve port is closed. This allows
As long as the inner space of the valve body is closed and gas leakage does not occur and there is no large temperature difference between the inside and outside of the telescopic container, the pressure difference between the inside and outside of the telescopic container is extremely small, and the telescopic container depends on the inside and outside pressure difference Small deformation, no risk of breakage.

On the other hand, when the compressor is started to operate the refrigeration cycle, the pressure in the space upstream of the refrigerant passage between the radiator and the evaporator (pressure at the outlet of the radiator) is increased by the internal pressure in the inner space of the valve body. When the pressure becomes larger, the first valve port is opened by the check valve, whereby when the internal pressure of the inner space of the valve body becomes larger than the internal pressure of the telescopic container, the valve opens the second valve port,
Refrigerant circulates through the piping. And the temperature inside the telescopic container is
Due to the heat conduction of the enclosed refrigerant, the temperature in the thermosensitive cylinder, that is, the temperature of the refrigerant pipe provided with the thermosensitive cylinder, changes in conjunction with the temperature, so the pressure in the telescopic container becomes a balance pressure with respect to the temperature of the refrigerant pipe, When the radiator outlet pressure is higher than the balance pressure, the second valve port is opened, and when the radiator outlet pressure is lower than the balance pressure, the second valve port is closed. The pressure control valve of the present invention, after increasing the outlet pressure corresponding to the radiator outlet temperature to a predetermined pressure, opens the valve, and targets the radiator outlet pressure in accordance with the refrigerant temperature at the radiator outlet side. Pressure can be controlled.

Here, the invention according to claim 2 is provided with a communication pipe for communicating between the inside of the valve body and the inside of the telescopic container, and a closing valve provided in the communication pipe. In the present invention, at the time of the initial setting, by introducing the refrigerant gas into the valve body with the closing valve opened, for example, from the first valve port side, the refrigerant gas passes through the communication pipe into the telescopic container. The refrigerant gas is introduced into the temperature-sensitive cylinder through the pipe member, and by closing the shut-off valve here, the refrigerant gas can be easily introduced into the valve body, the shrinking container, and the temperature-sensitive cylinder. Here, the refrigerant is carbon dioxide, and the refrigerant to be charged is 10.5 ± 0.1 at 40 ± 1 ° C.
Preferably, it is carbon dioxide gas of 5 MPa.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a vapor compression refrigeration cycle provided with a pressure control valve according to the present invention.
FIG. 2 is a sectional view showing details of a pressure control valve shown in FIG. 1.

First, as shown in FIG. 1, a vapor compression refrigeration cycle using a pressure control valve according to the present embodiment is, for example, a CO ₂ cycle applied to a vehicle air conditioner. _It is a compressor that compresses ₂ . The compressor 1 is driven by obtaining a driving force from a driving source (not shown) such as an engine. Reference numeral 2 denotes a gas cooler (radiator) for exchanging heat between the CO ₂ compressed by the compressor 1 and the outside air or the like to cool the CO _2. Reference numeral 3 denotes a pressure control valve provided on a pipe on the outlet side of an intercooler 7 described later. It is. The pressure control valve 3 controls the pressure on the gas cooler 2 outlet side (in this example, the high side on the outlet side of the intercooler 7) in accordance with the CO ₂ temperature (refrigerant temperature) detected by the temperature-sensitive cylinder 11 described later on the gas cooler 2 outlet side. Pressure). The pressure control valve 3 controls high pressure and also functions as a pressure reducing device, and its structure and operation will be described later in detail. CO ₂ is decompressed by the pressure control valve 3 and is in a low-temperature, low-pressure gas-liquid two-phase state.
The pressure becomes O ₂ , and the pressure is further reduced by the diaphragm resistor 4a (a diaphragm means).

Reference numeral 4 denotes an evaporator (evaporator) serving as air cooling means in the passenger compartment. When CO ₂ in a gas-liquid two-phase state is vaporized (evaporated) in the evaporator 4, it takes off latent heat of evaporation from the air in the passenger compartment. To cool the cabin air. 5 is a liquid refrigerant 5a
The evaporator 4 has an outlet pipe 6 vertically penetrating the liquid reservoir 5, and the liquid refrigerant 5a in the liquid reservoir 5 and the liquid refrigerant in the pipe 6 are heated by the heat. It is configured to be replaced. The penetrating portion of the pipe 6 of the liquid reservoir 5 is sealed (not shown) so that the inside of the liquid reservoir 5 is a closed space. The bottom of the liquid reservoir 5 is connected to the communication pipe 5.
b, the piping 6 between the pressure control valve 3 and the throttle resistance 4a
Is in communication with The intercooler 7 is a countercurrent heat exchanger that exchanges heat between the liquid refrigerant that has passed through the gas cooler 2 and the gas refrigerant that has passed through the evaporator 4. This is for improving the response speed, and is not necessarily provided. When the intercooler 7 is not provided, it is preferable to provide the pressure control valve 3 in a pipe near the outlet of the gas cooler 2. And compressor 1, gas cooler 2, intercooler 7, pressure control valve 3, throttle resistance 4
a and the evaporator 4 are connected by a pipe 6 to form a closed circuit (CO ₂ cycle). Reference numeral 8 denotes an oil separator that collects lubricating oil from refrigerant gas discharged from the compressor 1, and the collected lubricating oil is returned into the compressor 1 through an oil return pipe 9.

Here, an embodiment of the pressure control valve 3 will be described in detail. As shown in FIG. 2, a valve body 12 (valve casing) of the pressure control valve 3 includes an intercooler 7 and a throttle resistor 4 a (each in a CO ₂ flow path) formed by a pipe 6. 1 (see FIG. 1). Further, the valve body 12 is disposed so as to partition the refrigerant passage 7 into an upstream space 7a and a downstream space 7b, and within both orthogonal ends of the valve body 12, an upstream space 7a of the refrigerant passage 7 is provided. First partition 1 which is the boundary of
3 and a second partition 1 which is a boundary with the downstream space 7b
4 are formed, and the first partition 13 and the second partition 13 are formed.
A first valve port 13a (opening) and a second valve port 14a (opening) are formed in the partition wall 14.

The inner space 12a of the valve body 12 is provided with an expandable container 17 made of bellows for forming a closed space 17a, and the expandable container 17 is pivoted according to a pressure difference between the inside and the outside of the closed space 17a. It expands and contracts in the direction (vertical direction indicated by arrow A in FIG. 1). This telescopic container 17
The base end (the upper end in FIG. 1) is fixed to the inner wall of the valve main body 12.
A valve stem 16a having a valve 16 at its tip penetrates movably in the axial direction (direction of arrow A). The valve 16 is fixed to the tip of the telescopic container 17 and faces the second valve port 14a of the second partition 14. The valve stem 16a is movable mechanically in conjunction with the expansion and contraction of the telescopic container 17,
When there is no pressure difference between the inside and outside of the closed space 17a of the telescopic container 17 and the telescopic container 17 is in a no-load state, the valve 16 closes the second valve port 14a.

Reference numeral 15 is provided in the valve body 12,
A check valve for opening and closing the first valve port 13a is shown, and the check valve 15 is configured such that the pressure in the upstream space 7a is
The first valve port 13a is opened when the internal pressure of the second internal space 12a becomes larger than the internal pressure by a predetermined amount. The check valve 21 is connected to the first valve port 13a by a biasing means (not shown) (for example, a coil spring).
, And a predetermined initial load is always applied to the check valve 15. This initial load is the predetermined amount.

The closed space 17a of the telescopic container 17 communicates with the temperature sensing tube 11 via a capillary tube 10 (tube member). The temperature sensing tube 11 is housed in the large diameter portion 6 a of the pipe 6 near the outlet of the gas cooler 2, and detects the temperature of the refrigerant in the pipe 6 and transmits it to the telescopic container 17. In consideration of the good thermal response of the temperature-sensitive cylinder 11,
Although the temperature sensing tube 11 is provided in the pipe 6, the invention is not limited thereto, and the temperature sensing cylinder 11 may be provided in close contact with the outer surface of the pipe 6. Communication tube 19 (narrow tube)
Are the inner space 12a of the valve body 12 and the capillary tube 1
The communication pipe 19 is provided with a shut-off valve 18. When the closing valve 18 is closed, the inner space 12a of the valve body 12 and the closed space 17a of the telescopic container 17 are closed and become independent spaces. The vapor compression refrigeration cycle of this example is a CO ₂ cycle using a refrigerant and carbon dioxide, and a refrigerant gas (CO 2) is stored in the valve body 12, the telescopic container 17, the temperature-sensitive cylinder 11, and the capillary tube 10. ₂ gas), the valve 16
And in a state in which the check valve 15 is closed,
The refrigerant gas is sealed at a predetermined density ranging from a saturated liquid density at a temperature of 0 ° C. to a saturated liquid density at a critical point of the refrigerant.

Next, the method of use and operation of the pressure control valve 3 will be described. First, at the time of initial setting, the closing valve 18
Is opened, C is introduced into the valve body 12 through the first valve port 13a.
By introducing the O ₂ gas, a part of the CO ₂ gas passes through the communication tube 19 and the capillary tube 10 and
The check valve 15 is automatically introduced into the closed space 17a of the telescopic container 17 and the temperature-sensitive cylinder 11, and when the introduction is completed, the check valve 15 is automatically closed.
Inner space 12a and closed space 17a of the telescopic container 17
Are independent spaces separated from each other by no internal pressure difference.
As a result, the pressure in the closed space 17a of the shrinkable container 17 becomes a pressure corresponding to the temperature of the thermosensitive cylinder 11, and the pressure corresponding to the valve body 12 is maintained outside the shrinkable container 17, so that the pressure shrinks unless a large temperature difference occurs. Since the pressure difference between the inside and the outside of the container 17 does not increase, the shrinkable container 17 is not excessively deformed, and there is no possibility that the elastic restoring force is reduced or broken. In addition,
CO ₂ temperature at the outlet of the intercooler 7 is 40 ± 1 ℃
Is assumed, the pressure of the enclosed CO ₂ gas is preferably 10.5 ± 0.5 MPa so that the coefficient of performance is maximized.

At the end of the initialization, the first valve port 13a and the second valve port 14a are closed by the check valve 15 and the valve 16, respectively. When the compressor 1 is started to operate the CO ₂ cycle, when the pressure in the upstream space 7 a of the pressure control valve 3 becomes larger than the internal pressure of the valve body 12, the check valve 15 moves and the first valve port 13 a is closed. Open, whereby CO ₂ gas flows into the valve body 12. When the internal pressure of the valve body 12 becomes larger than the internal pressure of the contraction container 17, the valve 16 moves, the second valve port 14a opens, and CO ₂ circulates in the pipe 6.
At this time, due to the heat conduction of the enclosed CO ₂ gas, the temperature in the telescopic container 17 is linked with the temperature in the temperature-sensitive cylinder 11,
It becomes almost equal to the gas cooler 2 outlet temperature. Therefore, the internal pressure of the telescopic container 17 is a balance pressure of the temperature of the circulating CO ₂ . When the internal pressure of the valve body 12 is larger than the balance pressure, the second valve port 14a is in an open state, and when the internal pressure of the valve body 12 is smaller than the balance pressure, the second valve port 14 is in a closed state, Thereby, the balance pressure corresponding to the temperature on the outlet side of the gas cooler 2 is automatically adjusted so as to be substantially equal to the internal pressure of the valve body 12. That is, the pressure at the outlet of the intercooler 7 is controlled according to the CO ₂ temperature at the outlet of the gas cooler 2.

More specifically, for example, the temperature on the outlet side of the gas cooler 2 is 40 ° C. and the outlet pressure of the gas cooler 2 is about 1
When the pressure is 0.7 MPa or less, since the pressure control valve 3 is closed, the compressor 1 sucks CO ₂ from the intercooler 7 and discharges it to the radiator 2. As a result, the outlet pressure of the radiator 2 increases (b′-c ′ in FIG. 5).
→ b "-c"). When the pressure on the outlet side of the radiator 2 exceeds about 10.7 MPa (BC), the pressure control valve 3
Is opened, the CO ₂ changes phase from the gas phase state to the gas-liquid two-phase state while reducing the pressure (C-D), and flows into the evaporator 4. After evaporating in the evaporator 4 (DA), the air is cooled and then returned to the intercooler 7 again. At this time, since the outlet pressure of the radiator 2 decreases again, the pressure control valve 3 closes again.

That is, in the CO ₂ cycle, the pressure on the outlet side of the radiator 2 is increased to a predetermined pressure by closing the pressure control valve 3, and then the CO ₂ is reduced and evaporated to cool the air. is there. As described above, the pressure control valve 3 according to the present embodiment opens the valve after the pressure on the outlet side of the radiator 2 is increased to a predetermined pressure, and the control characteristic is the high pressure control valve 3. Greatly depends on the pressure characteristics of the enclosed space. By the way, as is clear from FIG. 3, the isopycnic line of 600 kg / cm ³ in the supercritical region almost coincides with the above-mentioned optimal control line η _max . Accordingly, the pressure control valve 3 according to the present embodiment increases the pressure on the outlet side of the radiator 2 to a pressure substantially along the optimal control line η _max , so that the CO ₂ cycle can be efficiently operated even in the supercritical region. Can be. And below supercritical pressure, 600k
Although the deviation of the isopycnic line of g / m ³ from the optimal control line η _max becomes large, the internal pressure of the closed space changes along the saturated liquid line SL because of the condensing region. Practically, it is desirable to seal the inside of the closed space in a range from a saturated liquid density at a CO ₂ temperature of 0 ° C. to a saturated liquid density at a critical point of CO ₂ .

By the way, as is apparent from the above description of the operation and characteristics, it is desirable that the temperature in the closed space 17a of the telescopic container 17 changes in conjunction with the temperature of the radiator outlet side without a time difference. Therefore, the elastic container 17
In order to increase the amount of heat conduction as much as possible, a material having large heat conduction and a small thickness (for example, stainless steel) is preferable. Instead of using bellows for the telescopic container 17, a diaphragm may be used.

In this embodiment, the bellows, diaphragm and the like can be used to operate at a low pressure difference between the inside and outside of the telescopic container 18, and even if the pressure resistance of the telescopic container 18 is low, the differential pressure between the inside and outside is small. Even if a conventional material is used, there is no danger of breakage and deformation, and a high pressure (in this example, 500 kg
The / m ³ ~800kg / m ³⁾ of CO ₂ was possible inclusion.
In addition, when the pressure in the pipe 6 is greatly reduced due to gas leakage or the like during use in the refrigeration cycle, the check valve 21 is closed, so that the pressure in the valve body 12 does not decrease significantly. It is hard to break and does not break.

Next, the automatic adjustment of the circulating refrigerant amount will be described. First, when the refrigerant temperature at the outlet of the gas cooler 2 decreases, the pressure control valve 3 is opened as described above in order to reduce the high side pressure so that the coefficient of performance of the supercritical vapor compression cycle is maximized. As the degree increases, the refrigerant pressure between the pressure control valve 3 and the throttle resistor 4a increases. As a result, part of the refrigerant in the pipe 6 between the pressure control valve 3 and the throttle resistor 4a passes through the communication pipe 5b,
And, as a result, the amount of refrigerant circulated in the cycle is automatically reduced. On the other hand, when the refrigerant temperature at the outlet of the gas cooler 2 increases, in order to increase the high side pressure so that the coefficient of performance of the supercritical vapor compression cycle is maximized,
As described above, as the opening of the pressure control valve 3 decreases, the refrigerant pressure in the pipe 6 between the pressure control valve 3 and the throttle resistor 4a decreases. As a result, the refrigerant in the liquid reservoir 5 passes through the communication pipe 5b, and the pressure control valve 3 and the throttle resistance 4
As a result, the refrigerant circulates in the cycle automatically increases.

When the amount of the refrigerant flowing out of the evaporator 4 decreases and the capacity of the cycle is insufficient, the refrigerant flowing out of the evaporator 4 becomes overheated, and when the refrigerant passes through the inside of the liquid reservoir 5, The liquid refrigerant is heated, and when the pressure of the liquid refrigerant becomes equal to or higher than the saturation pressure, the communication pipe 5
b flows into the pipe 6 between the pressure control valve 3 and the throttle resistor 4a. As a result, the amount of circulating refrigerant in the cycle increases, and the capacity increases. On the other hand, if the amount of refrigerant flowing out of the evaporator 4 increases and the capacity of the cycle is excessive, the evaporator 4
Refrigerant flowing out of the reservoir cools the liquid refrigerant therein when passing through the liquid reservoir 5, and when the pressure of the refrigerant becomes lower than the saturation pressure, the refrigerant in the pipe 6 between the pressure control valve 3 and the throttle resistor 4a is cooled. Part of the refrigerant flows into the liquid reservoir 5 through the communication pipe 15b, and as a result, the amount of refrigerant circulated in the cycle decreases, and the capacity decreases.

[0028]

Since the present invention is configured as described above, it has the following effects. According to the first aspect of the present invention, when the operation of the refrigeration cycle is stopped, the second valve port is closed by the valve of the telescopic container. Close the valve port. As a result, the internal space of the valve body is closed and gas leakage does not occur. Unless a large temperature difference occurs between the inside and outside of the telescopic container, the pressure difference between the inside and outside of the telescopic container becomes extremely small. Deformation due to pressure difference is small and there is no fear of breakage.

On the other hand, during operation of the refrigeration cycle, the outlet pressure corresponding to the radiator outlet temperature is increased to a predetermined pressure, and then the valve is opened to open the radiator outlet temperature and the radiator outlet pressure. (High side pressure) is automatically controlled substantially along the optimal control line, so that the vapor compression cycle operating in the supercritical region can be operated efficiently.

According to a second aspect of the present invention, at the time of initial setting, by introducing a refrigerant gas into the valve body from the first valve port side, for example, with the closing valve opened, the refrigerant gas flows through the communication pipe. Through the pipe member and into the temperature-sensitive cylinder through the pipe member, and by closing the shut-off valve, the refrigerant gas is introduced into the valve body, the shrinking vessel and the temperature-sensitive cylinder. Can be easily introduced. Here, the refrigerant is carbon dioxide, and the refrigerant to be charged is 1 at 40 ± 1 ° C.
Preferably, it is carbon dioxide gas of 0.5 ± 0.5 MPa. As described above, bellows, enabling operation at a low pressure difference inside and outside the telescopic container using a diaphragm,
Since the differential pressure between the inside and outside of the expandable container is small even if the pressure resistance of the expandable container is low, even if a conventional material is used for the bellows or the like, there is no possibility of breakage and deformation, and a high-pressure refrigerant (particularly, CO ₂ ) can be sealed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a vapor compression refrigeration cycle including a pressure control valve according to the present invention.

FIG. 2 is a sectional view showing details of a pressure control valve shown in FIG. 1;

FIG. 3 is a graph for explaining the operation of a vapor compression refrigeration cycle.

FIG. 4 is a Mollier diagram of CO ₂ .

FIG. 5 is a graph showing a relationship between a coefficient of performance (COP) and a radiator outlet pressure.

FIG. 6 is a sectional view of a conventional pressure control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Gas cooler (radiator) 3 Pressure control valve 4 Evaporator (evaporator) 5 Liquid reservoir 6 Pipe 7 Refrigerant passage 7a Upstream space (upstream passage) 7b Downstream space (downstream passage) 10 Capillary tube DESCRIPTION OF SYMBOLS 11 Temperature sensing cylinder 12 Valve body 13a 1st valve port 14a 2nd valve port 15 Check valve 16 Valve 17 Telescopic container 18 Closing valve 19 Communication pipe

Claims (3)

[Claims] 1. A radiator outlet side pressure is controlled to a target value in accordance with a refrigerant temperature at a radiator outlet side, which is disposed in a refrigerant passage from a radiator to an evaporator of a vapor compression refrigeration cycle. In the pressure control valve, a first space is provided on an upstream space side and a downstream space side of the refrigerant passage.
A valve body in which a valve port and a second valve port are respectively formed; a telescopic container provided in an inner space of the valve body so as to be displaceable according to a pressure difference between an inside and an outside of an internal sealed space; A temperature-sensitive cylinder provided in the refrigerant passage near the outlet of the radiator, and communicated with the telescopic container through a pipe member, and for transmitting the refrigerant temperature near the outlet of the radiator into the telescopic container; A valve that is fixed to a container and opens the second valve port when the telescopic container is displaced; provided in the valve body, the pressure in the upstream space is greater than the pressure in the valve body. A check valve that opens the first valve port when the refrigerant flows into the valve body, the telescopic container, the temperature-sensitive cylinder, and the pipe member, and the valve and the check valve. A saturated liquid at a temperature of the refrigerant of 0 ° C. with the valves closed respectively. Vapor compression refrigeration cycle pressure control valve, characterized in that it is enclosed each at a density of a predetermined range leading to saturated liquid density at the critical point of the refrigerant from the time. 2. A pressure control valve for a vapor compression refrigeration cycle according to claim 1, further comprising a communication pipe for communicating between the inside of the valve body and the inside of the telescopic container, and a closing valve provided in the communication pipe. . 3. The refrigerant is carbon dioxide, and the refrigerant to be charged has a pressure at 40 ± 1 ° C. of 10.5 ± 0.1.
3. The pressure control valve for a vapor compression refrigeration cycle according to claim 1, wherein the pressure control valve is carbon dioxide gas of 5 MPa.