JP2002372346A - Refrigerant circuit, its operation checking method, method for filling refrigerant, and closing valve for filling refrigerant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerant circuit and an operation checking method for improving reliability of a product by preventing leakage of a refrigerant, and also to provide a method for filling the refrigerant and a closing valve for filling the refrigerant enabling a supercritical refrigerant to be filled highly accurately and contributing to reduction of costs. SOLUTION: The refrigerant circuit is made into a pressure reduced state via a communication port 15 provided on a low pressure side between a pressure reducing unit 4 and an evaporator 5, and then the refrigerant is filled through the communication port 15 while a pressure sensor 19 on a high pressure side is being calibrated. The pressure reducing unit 4 is provided with a total-closure inhibiting function S.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant circuit, a method for inspecting the operation of the circuit, a method for charging the refrigerant, and a shutoff valve for charging the refrigerant.

[0002]

2. Description of the Related Art There is a heat pump type hot water supply apparatus as an apparatus using a refrigerant circuit. That is, the heat pump hot water supply device includes a tank unit having a hot water storage tank and a heat source unit having a refrigerant circuit, and the refrigerant circuit is used for this heat source unit. The refrigerant circuit generally includes a compressor, a condenser, a decompression mechanism, and an evaporator, and allows water (hot water) to flow out of an intake port on the bottom wall of the hot water storage tank to the circulation path, and to be provided in the circulation path. Heat exchanger (condenser)
The hot water is then boiled and returned to the hot water storage tank through the water supply port at the top of the hot water storage tank. Thus, high-temperature hot water is stored in the hot water storage tank.

Conventionally, refrigerants such as dichlorodifluoromethane (R-12) and chlorodifluoromethane (R-22) have been used as refrigerants in the refrigerant circuit. Due to problems such as contamination, 1,1,1,2-tetrafluoroethane (R-13
An alternative refrigerant such as 4a) is used. However, since R-134a still has a problem such as high global warming ability, use of a natural refrigerant free of such a problem has been recently recommended. It is known that a supercritical refrigerant such as carbon dioxide is useful as the natural refrigerant.

[0004]

In the refrigerant circuit of the heat source unit, it is necessary to verify the refrigeration cycle formed. In this case, in the refrigerant circuit not using the supercritical refrigerant, a port was provided in the refrigerant pipe, and the pressure was measured through this port, so that the operation state (refrigeration cycle) could be verified. And the port was constituted by, for example, a valve. However, in such a valve, the portion to be brazed to the refrigerant pipe is inferior in sealing performance as compared with other connection portions, and in a refrigerant circuit using a supercritical refrigerant, the pressure in the refrigerant pipe is high, so that refrigerant leakage may occur. There was a risk of occurrence. If a refrigerant leak occurs, the operation is performed with an excessively small amount of the refrigerant, so that the compressor suction heating increases and the discharge pipe temperature increases. For this reason, it is necessary to lower the frequency of the compressor from the viewpoint of protection of the compressor. If the frequency is lowered, the performance of the compressor is reduced. If the compressor is not protected even at the lowest frequency of the compressor, the operation becomes impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional disadvantages, and one object of the present invention is to provide a refrigerant circuit capable of preventing the occurrence of refrigerant leakage and improving the reliability of products. And to provide an operation inspection method thereof,
It is another object of the present invention to provide a refrigerant charging method and a refrigerant charging shut-off valve capable of filling a supercritical refrigerant with high accuracy and contributing to cost reduction.

[0006]

Accordingly, a refrigerant circuit according to claim 1 has a compressor 1, a condenser 2, a decompression mechanism 4, and an evaporator 5, and uses a supercritical refrigerant used in supercritical condition. In the low-pressure side, a communication port 15 to which a refrigerant filling device 40 having a vacuum pump 41 and the like is detachably attached is provided, and the pressure reducing mechanism 4 is provided with a fully-closed preventing function S.
It is characterized by having attached.

In the refrigerant circuit according to the first aspect, since the pressure reducing mechanism 4 is provided with the fully closed preventing function S, the pressure reducing mechanism 4 is not completely closed, and the vacuum pump for performing the refrigerant charging operation by the refrigerant charging device is used. In the evacuation step, the entire refrigerant pipe of the refrigerant circuit can be reliably reduced in pressure (vacuum state). In addition, only a communication port provided on the low pressure side is required as a port, so that refrigerant leakage can be suppressed.

The refrigerant circuit according to a second aspect is characterized in that a high pressure side pressure sensor 19 comprising a pressure detecting element is provided.

In the refrigerant circuit of the second aspect, if the refrigerant charging device has a pressure detector, the high pressure side pressure sensor 19 can detect the high pressure side pressure as well as the low pressure side pressure. .

An operation inspection method according to a third aspect is an operation inspection method for a refrigerant circuit using a supercritical refrigerant used in a supercritical state, wherein the pressure detector 43 is detachably connected to the communication port 15 provided on the low pressure side. In addition to the measurement of the pressure on the low pressure side by the pressure detector 43, the pressure on the high pressure side is measured by the high pressure side pressure sensor 19 composed of a pressure detecting element.

According to the operation inspection method of the third aspect, it is possible to detect the low pressure side pressure by the pressure detector 43 of the communication port 15 and the high pressure side pressure by the high pressure side pressure sensor 19. In addition, only a communication port provided on the low pressure side is required as a port, so that refrigerant leakage can be suppressed.

According to a fourth aspect of the present invention, there is provided a refrigerant charging method for charging a supercritical refrigerant into a refrigerant circuit using a supercritical refrigerant used in a supercritical state. After the refrigerant circuit is evacuated through the communication port 15 provided on the low pressure side using the pressure reducing mechanism 4, the refrigerant is charged from the communication port 15 while the high pressure side pressure sensor 19 is calibrated. Features.

In the refrigerant charging method according to the fourth aspect, the refrigerant is charged from the communication port 15 after the refrigerant circuit is evacuated (after evacuation), so that the refrigerant can be easily charged. Moreover, since the pressure reducing mechanism 4 having the fully closed function S is used in the refrigerant circuit, the entire flow path (piping) of the refrigerant circuit can be evacuated when evacuating. Furthermore, when charging the refrigerant, the high pressure side pressure sensor 19 can be calibrated, and the reliability of the high pressure side pressure sensor 19 is increased. In addition, only a communication port provided on the low pressure side is required as a port, so that refrigerant leakage can be suppressed.

A refrigerant charging shut-off valve according to a fifth aspect of the present invention is a refrigerant charging shut-off valve for charging a supercritical refrigerant into a refrigerant circuit using a supercritical refrigerant. A movable valve rod 33, and an elastic member 36 that presses the valve rod 33 in the axial direction to maintain the valve open state, and is attached to the low pressure side. While allowing the circuit to be evacuated, the refrigerant circuit can be charged with the refrigerant in the vacuum state, and the valve rod 33 resists the urging force of the elastic member 36 due to the pressure of the refrigerant in the refrigerant circuit when the refrigerant charging is completed. It is characterized in that it is pressed to be in a valve-closed state to prevent the refrigerant from flowing out.

According to the fifth aspect of the present invention, the valve is kept open by the elastic member 36. In this state, the refrigerant circuit can be evacuated. Since the refrigerant can be charged, the refrigerant circuit can be charged with the refrigerant. When the refrigerant circuit is completely charged with the refrigerant, the pressure at which the refrigerant is charged into the closing valve is released. As a result, the valve rod 33 is pressed against the urging force of the resilient member 36 by the pressure of the refrigerant from the refrigerant circuit to be in a valve-closed state, thereby preventing the refrigerant from flowing out. By the way, when the valve rod 33 is pressed in the direction of opening in the valve closed state against the pressure of the refrigerant, the valve rod 33 is opened and the refrigerant in the refrigerant circuit can be discharged.

[0016]

Next, a specific embodiment of the refrigerant circuit of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a simplified diagram of a refrigerant circuit, which is used, for example, in a heat source unit of a heat pump water heater. The refrigerant circuit includes a compressor 1, a condenser (in this case, a water heat exchanger) 2, a receiver 3, a pressure reducing mechanism 4, and an evaporator 5, and as a refrigerant, for example, carbon dioxide used in supercritical (CO2) is used. Further, a liquid-gas heat exchanger 6 for cooling the refrigerant flowing out of the condenser 2 is provided, and an accumulator 8 is provided in a suction passage 7 of the compressor 1.
Is provided.

The liquid-gas heat exchanger 6 has a first passage 6a through which the refrigerant from the condenser 2 passes and a second passage 6b through which the refrigerant from the evaporator 5 passes. That is, the first passage 6a
Constitutes a part of a refrigerant flow path 10 connecting the condenser 2 and the receiver 3, and forms a part of a refrigerant flow path 11 connecting the evaporator 5 and the accumulator 8 to the second passage 6 b. Therefore, heat is exchanged between the high-temperature and high-pressure refrigerant passing through the first passage 6a and the low-temperature and low-pressure refrigerant passing through the second passage 6b.
The refrigerant entering the receiver 3 is cooled. The receiver 3
The pressure reducing mechanism 4 and the evaporator 5 are connected by a flow path 13, and the compressor 1 and the condenser 2 are connected by a flow path 14.

A communication port 15 is provided on the low pressure side, that is, between the pressure reducing mechanism 4 and the evaporator 5. That is, the communication port 15 is provided in the flow path 13, and the communication port 1
5, a refrigerant charging device 40 described later is detachably attached. In this case, the closing port 30 for charging the refrigerant shown in FIG. 3 is used for the communication port 15. A high-pressure side pressure sensor 19 composed of a pressure detecting element is provided in the flow path 14.

Incidentally, the pressure reducing mechanism 4 in this case comprises, for example, an electric expansion valve 20 and is provided with a fully-closed preventing function S as shown in FIG. That is, the expansion valve 20
A valve body 22 having a valve chamber 21, a valve element 23 included in the valve chamber 21, and a valve seat 24 for receiving the valve element 23 are provided. The valve body 23 is formed of a cone, and the valve seat 24 is provided with grooves 25. Therefore, as shown in FIG.
Are formed between the outer surface of the valve seat 24 and the valve seat 24. Therefore, a full-close prevention function S is mechanically prevented from being fully closed by the small passage 26.
Even when the valve 4 is received by the valve body 23, the electric expansion valve 20 is not fully closed.

As shown in the phantom line in FIG. 1, a bypass circuit 27 for connecting the flow path 12 and the flow path 13 is provided as the fully closed prevention function S, and a capillary tube 28 is provided in the bypass circuit 27. It may be formed by doing. That is, the pressure reducing mechanism 4 is configured by a normal expansion valve 20 having no full-close prevention function S and a bypass circuit 27 having a capillary tube 28. Therefore, even if the expansion valve 20 itself is closed (in this case, the fully closed state is possible), the refrigerant flows through the capillary tube 28 of the bypass circuit 27, and the pressure reducing mechanism 4 does not enter the fully closed state. Therefore, even with the decompression mechanism 4 using the capillary tube 28 shown by the phantom line, the same operation and effect as the expansion valve 20 shown in FIG. 1 can be exhibited.

Next, the closing valve 30 for charging the refrigerant is shown in FIG.
As shown in FIG. 1, a valve body 32 having a valve chamber 31, a valve rod 33 housed in the valve chamber 31 so as to reciprocate in its axial direction, and a valve seat for receiving a valve element 34 of the valve rod 33 35,
A resilient member 36 is provided for urging the valve rod 33 in a direction (uniaxial direction) for separating the valve rod 33 from the valve seat 35. That is, in the free state, the urging force of the resilient member 36 moves the valve body 34 away from the valve seat 35 to maintain a so-called valve open state. Then, the valve rod 33 is moved against the urging force of the resilient member 36 as shown in FIG.
, The valve body 34 comes into contact with or presses against the valve seat 35 to be in a so-called valve closed state.

In the refrigerant filling closing valve 30, a pipe 37 protruding from the base end of the valve body 32 is attached to the flow path 13 and a pipe 3 protruding from the tip of the valve body 32.
8 is attached to the refrigerant charging device 40. Here, the refrigerant charging device 40 is for charging the refrigerant in the refrigerant circuit, and includes a vacuum pump 41, a refrigerant cylinder 42, and a pressure detector 43. That is, a pipe 44 is detachably connected to the pipe 38 via a connection member (not shown) such as a coupling. The pipe 44 is connected to a first pipe 45 connected to a vacuum pump 41 and a refrigerant cylinder 42. A second pipe 46 is connected to a third pipe 47 to which the pressure detector 43 is connected. The first pipe 45 has an on-off valve 48.
And an on-off valve 49 is provided in the second pipe 46,
An on-off valve 50 is provided in the third pipe 47. By the way, the closing valve 30 for charging the refrigerant has the valve rod 33 in the valve open state.
A gap is provided between the outer surface of the valve chamber 31 and the inner surface of the valve chamber 31, and the pipe 37 and the pipe 38 are in communication with each other. Further, if the refrigerant charging closing valve 30 is closed against the urging force of the resilient member 36, the pipe 37 and the pipe 38 are shut off.

Next, a method of evacuating the refrigerant circuit and charging the refrigerant will be described. As shown in FIG.
0 is attached to the communication port 15, that is, the refrigerant charging stop valve 30. In this state, the refrigerant charging closing valve 30 is in an open state by the urging force of the resilient member 36. Therefore, the on-off valves 49 and 50 are closed and the on-off valves 4 and 50 are closed.
8 is opened, and the vacuum pump 41 is driven (operated). As a result, the inside of the refrigerant circuit is evacuated via the refrigerant charging closing valve 30 to be in a reduced pressure state (vacuum state).
In this case, the pressure reducing mechanism (electric expansion valve) 4 is provided with the fully-closed preventing function S.
Therefore, the entire piping (flow path) of the refrigerant circuit can be evacuated. Thereafter, while maintaining this vacuum state, the on-off valve 48 is closed and the on-off valve 49 is opened to fill the refrigerant. At this time, the liquid or gas refrigerant from the refrigerant cylinder 42 is supplied to the refrigerant circuit by utilizing the pressure difference.
The charging can be performed through the refrigerant charging closing valve 30 which is in the open state. At this time, if the refrigerant is a liquid refrigerant, a sufficient amount can be easily filled without operating the refrigerant circuit. In addition, in the case of charging the liquid refrigerant, it is preferable to set the port position before and after the expansion valve 4 from the viewpoint of preventing the liquid refrigerant from being sucked into the compressor 1. When the refrigerant is charged during operation, the communication port 15 is connected to a position (low pressure side) downstream of the expansion valve 4 as shown in the figure. This is because it is difficult on the high pressure side because a pressure difference is required.

The confirmation of the refrigerant charge amount can be performed by detecting the increase amount of the product weight or the decrease amount of the refrigerant cylinder 42. In particular, for checking while operating, the charged amount is checked based on the reduced amount of the refrigerant cylinder 42. Further, there is a method of charging the refrigerant until a predetermined refrigeration cycle (high and low pressures, each part temperature is a predetermined value) is reached. When the charging step is completed, the refrigerant pressure in the refrigerant circuit (for example, 30 kg
/ Cm ^{2 to} 50 kg / cm ² )
Is pushed as shown by the arrow in FIG.
Therefore, the valve rod 33 is pushed toward the valve seat 35 against the urging force of the resilient member 36, and the valve body 34 comes into contact with the valve seat 35 to be in a valve closed state. This prevents the charged refrigerant from flowing out.

After the filling, the high-pressure side pressure sensor 19 detects the high-pressure side pressure, and the pressure detector 43 detects the low-pressure side pressure to perform an operation inspection for verifying the refrigeration cycle. Can be. That is, after the refrigerant is charged, the on-off valves 49 and 48 are closed and the on-off valves 5
With 0 as an open state, the pressure is measured by the pressure detector 43,
The high pressure side pressure sensor 19 attached to the device is calibrated. In this case, since the pressure changes with the temperature, it is necessary to maintain the temperature at a constant state. Further, since the calibration cannot be performed at a temperature higher than the critical temperature, the temperature is preferably performed at a temperature lower than the critical temperature. Further, since the refrigerant in the refrigerant circuit when the operation is stopped is in an equilibrium state, the pressure is determined by the temperature. Therefore, as described above, it is possible to calibrate the pressure sensor (high-pressure side pressure sensor 19) attached to the device with the inspection pressure sensor (pressure detector 43). Thereafter, as shown in FIG. 4, when the refrigerant charging device 40 is removed from the refrigerant charging closing valve 30, the refrigerant charging and operation inspection work are completed.

The heat pump type hot water supply apparatus in which the refrigerant circuit shown in FIG. 1 is used as a heat source unit includes a hot water storage tank (not shown) and a circulation path 51. 2)
And a circulation pump (not shown) are provided. When the compressor 1 is driven and the water circulation pump 13 is driven (operated) in a state where the refrigerant circuit is filled with the refrigerant by the above-described charging method, the water intake port 10 provided at the bottom of the hot water storage tank 3 is formed. From the storage water (hot water) flows out, and flows through the heat exchange path 52 of the circulation path 51. At this time, the hot water is heated (boiled) by the condenser 2 which is a water heat exchanger, and is returned from the hot water supply port 11 to an upper portion of the hot water storage tank 3. By continuously performing such an operation, high-temperature hot water can be stored in the hot water storage tank. The refrigerant circuit includes a receiver 3 and a liquid-gas heat exchanger 6. The receiver 3 is for maintaining an appropriate amount of refrigerant circulating in the refrigerant circuit. 6
Is for adjusting the amount of refrigerant to be charged into the receiver 3. Thereby, an appropriate refrigeration cycle can be maintained even if there is a fluctuation in the outside air. Further, the second passage 6
Since the refrigerant passing through b is heated by the refrigerant passing through the first passage 6a, the refrigerant becomes superheated gas, and wet compression of the compressor 1 can be effectively prevented.

When it is necessary to recover (discharge) the refrigerant in the refrigerant circuit, as shown in FIG. 4, the pressure of the internal refrigerant is pressed as indicated by an arrow to maintain the valve closed state. When an external force is applied to the valve stem 33 along the axial direction of the valve stem 33 in a direction opposite to the arrow, as shown in FIG.
The valve rod 33 is pressed to be in the valve open state. When the valve is in the open state, the pipe 37 and the pipe 38 are in communication with each other, and the refrigerant in the refrigerant circuit is discharged. At this time, since the pressure reducing mechanism 4 does not enter the fully closed state, the refrigerant in the refrigerant circuit can be reliably discharged to the outside. The external force for opening the valve can be applied, for example, with a jig such as a rod-shaped body capable of pressing the valve rod 33 through the pipe 38.

As described above, the use of the refrigerant charging stop valve 30 makes it possible to simply and accurately fill an appropriate amount of refrigerant into the refrigerant circuit. Simple and inexpensive. In addition, when the valve rod 33 is pressed toward the refrigerant circuit in this filled state, the valve can be opened and the refrigerant can be discharged, so that the refrigerant can be easily recovered from the refrigerant circuit.

Although the specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be implemented with various modifications within the scope of the present invention. For example, when the expansion valve 20 as shown in FIG.
5 can be changed within a range that functions as an expansion valve of the refrigerant circuit. The groove 25 is not provided on the valve seat 24 side but is provided on the valve body 23 side. Or both. Further, as the resilient member 36 of the refrigerant charging closing valve 30, it is possible to restrict the valve closing state in the evacuation step, the refrigerant charging step, and the like, and to allow the valve closing state after the refrigerant charging. It is not limited to a coil spring as shown in the drawings as long as it has a biasing force that can be used, and various elastic materials can be used. The refrigerant may be a supercritical refrigerant such as ethylene, ethane, or nitrogen oxide, other than carbon dioxide. The position where the communication port 15 is provided may be anywhere on the low pressure side.

[0030]

According to the refrigerant circuit of the first aspect, the pressure reducing mechanism is not completely closed, and the refrigerant piping of the refrigerant circuit is used in the evacuation step by the vacuum pump when the refrigerant charging operation is performed by the refrigerant charging device. The whole can be reliably brought into a reduced pressure state (vacuum state). Thereby, the refrigerant can be easily and reliably charged. In addition, only a communication port provided on the low pressure side is required as a port, so that refrigerant leakage can be suppressed. As a result, defects due to refrigerant leakage are reduced, and the reliability of the product (refrigerant circuit) is improved.

According to the refrigerant circuit of the second aspect, if the refrigerant charging device has a pressure detector, the high pressure side pressure sensor can detect the high pressure side pressure and the low pressure side pressure can be detected. , Accurate driving inspection can be performed.

According to the operation inspection method of the third aspect, the low-pressure side pressure can be detected by the pressure detector of the communication port and the high-pressure side pressure can be detected by the high-pressure side pressure sensor. be able to. In addition, since the pressure reducing mechanism is not completely closed, the safety is excellent and the operation can be performed with confidence. In addition, refrigerant leakage can be suppressed.

According to the refrigerant charging method of the fourth aspect, the refrigerant can be easily filled, and at the time of charging, the high pressure side pressure sensor can be calibrated, and the reliability of the high pressure side pressure sensor is reduced. As the temperature increases, a specified amount of refrigerant can be charged. In addition, refrigerant leakage can be suppressed.

According to the fifth aspect of the present invention, the refrigerant can be easily and reliably charged into the refrigerant circuit. In addition, when the charging of the refrigerant in the refrigerant circuit is completed, the valve is in a closed state, and the outflow of the refrigerant is prevented, so that an appropriate refrigeration cycle can be maintained without running out of the refrigerant. By the way, in the valve closed state, if the valve rod is pressed in the direction to be opened against the pressure of the refrigerant, the valve can be opened and the refrigerant in the refrigerant circuit can be discharged, thereby simplifying the refrigerant recovery operation. In addition, there is an advantage that it can be performed in a short time. Further, the refrigerant charging stop valve can be configured with a simple structure, and the refrigerant charging stop valve can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a simplified diagram showing an embodiment of a refrigerant circuit of the present invention.

FIG. 2 is an enlarged sectional view of a main part of a pressure reducing mechanism of the refrigerant circuit.

FIG. 3 is a simplified diagram showing an embodiment of a refrigerant charging stop valve according to the present invention.

FIG. 4 is a simplified diagram of a refrigerant charging stop valve after the refrigerant charging.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 4 Decompression mechanism 5 Evaporator 15 Communication port 19 High pressure side pressure sensor 33 Valve stem 36 Resilient member 40 Refrigerant filling device 41 Vacuum pump 43 Pressure detector S Fully closed prevention function

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F25B 1/00 304 F25B 1/00 304Z 395 395Z 13/00 371 13/00 371 30/02 30/02 F

Claims (5)

[Claims] 1. A refrigerant circuit comprising a compressor (1), a condenser (2), a decompression mechanism (4), and an evaporator (5), wherein the refrigerant circuit uses a supercritical refrigerant used in supercritical. Beside
A communication port (15) to which a refrigerant filling device (40) having a vacuum pump (41) and the like are detachably attached is provided, and a fully-closed preventing function (S) is provided to the pressure reducing mechanism (4). Refrigerant circuit. 2. The refrigerant circuit according to claim 1, further comprising a high pressure side pressure sensor (19) comprising a pressure sensing element. 3. A method for inspecting the operation of a refrigerant circuit using a supercritical refrigerant used in a supercritical state, wherein a pressure reducing mechanism (4) having a fully closed prevention function (S) is used in the refrigerant circuit, A pressure detector (43) is detachably attached to the communication port (15) provided. In addition to the measurement of the pressure on the low pressure side by the pressure detector (43), the high pressure side pressure sensor ( An operation inspection method characterized by performing the pressure measurement on the high pressure side according to 19). 4. A refrigerant charging method for charging a supercritical refrigerant into a refrigerant circuit using a supercritical refrigerant used in supercritical mode, wherein the refrigerant circuit has a fully-closed preventing function (S). The communication port (1
5) A refrigerant charging method, wherein the refrigerant circuit is evacuated via 5), and then the refrigerant is charged from the communication port (15) while calibrating the high pressure side pressure sensor (19). 5. A shut-off valve for charging a supercritical refrigerant in a refrigerant circuit using a supercritical refrigerant used in a supercritical state, wherein the valve stem is capable of reciprocating in an axial direction.
And an elastic member (36) that presses the valve rod (33) in one axial direction to maintain the valve open state, and is attached to the low pressure side. In addition to allowing the pulling, the refrigerant circuit can be charged with the refrigerant in the vacuum state, and the valve rod (33) resists the urging force of the elastic member (36) by the pressure of the refrigerant in the refrigerant circuit when the refrigerant charging is completed. A refrigerant-filling shut-off valve, which is pressed to be in a valve-closed state to prevent refrigerant from flowing out.