JP7664742B2 - Air conditioner and pressure relief valve - Google Patents

Description

The present disclosure relates to a pressure relief valve that prevents damage to a pressure vessel such as a compressor housing, and an air conditioner equipped with a pressure relief valve.

Conventionally, separate-type air conditioners that are separated into an indoor unit and an outdoor unit have been developed. In separate-type air conditioners, it is known that when the air conditioner is relocated or disposed of, a forced cooling operation called pump-down is performed in which all of the refrigerant in the refrigerant circuit is recovered in the outdoor unit.

If, for some reason, a large amount of air gets into the refrigerant circuit when pumping down, the air is compressed in the compressor, and the high-temperature, high-pressure air mixes with the refrigeration oil. As a result, the pressure inside the compressor increases rapidly, and the compressor housing may be damaged.

To avoid the above damage, it may be prudent to install a pressure relief valve on the compressor.

For example, the pressure relief valve described in Patent Document 1 is attached to various pressure vessels and releases the pressure inside the pressure vessel to the outside when the pressure inside the pressure vessel exceeds a set value.

The pressure relief valve described in Patent Document 1 is provided with an outer cylinder with an opening at the top, an inner cylinder fitted into the outer cylinder, and a rupture disc whose outer periphery is sandwiched by a packing to close the openings of both the outer and inner cylinders. In this pressure relief valve, when the pressure inside the pressure vessel exceeds a set value, the rupture disc ruptures, opening the pressure relief valve and releasing the pressure inside the pressure vessel to the outside. This reduces the pressure inside the compression vessel and prevents damage to the pressure vessel.

Japanese Patent Application Publication No. 10-153299

The above-mentioned Patent Document 1 does not disclose the application of a pressure relief valve to an air conditioner.

The refrigerant circuit components that make up the refrigeration cycle include the heat exchanger, four-way valve, and compressor. To ensure safety, the pressure resistance of the refrigerant circuit components that make up the refrigeration cycle is designed to increase in order of the damage that would be caused by breakage. Of all the refrigerant circuit components, the compressor is the one that would be most susceptible to damage if broken, so it is designed to have the highest pressure resistance.

However, even if the compressor is designed to have a high pressure resistance, there is a possibility that the compressor housing may be damaged in some cases. An example of such a case is when a large amount of air gets into the refrigerant circuit during the above-mentioned pump-down. In that case, the speed at which the pressure rises inside the compressor is so fast that the speed at which the high-pressure gas propagates from the compressor to other refrigerant circuit components cannot keep up, and the compressor's pressure resistance is no longer able to withstand the pressure inside the compressor, which may damage the compressor housing. Note that when a large amount of air gets into the refrigerant circuit, the mixture of high-temperature, high-pressure air and refrigeration oil explodes inside the compressor due to the heat of compression, which is called a "diesel explosion." If a diesel explosion occurs, the compressor may be damaged.

As mentioned above, it is possible to provide a pressure relief valve in the compressor, but providing the pressure relief valve described in Patent Document 1 above has the following problems:

Since a compressor is a device that compresses and discharges the sucked refrigerant, pressure fluctuations are always occurring inside the compressor when the compressor is operating normally. Therefore, if the pressure relief valve described in Patent Document 1 is provided in the compressor, the pressure fluctuations inside the compressor will always be applied to the rupture disk of the pressure relief valve. This causes a problem in that the rupture disk may be fatigued and broken by the pressure fluctuations, and the pressure relief valve may open at a level lower than the intended set value, i.e., at the same level as the pressure fluctuations during normal operation.

The present disclosure has been made to solve such problems, and aims to provide a pressure release valve that prevents fatigue failure caused by normal pressure fluctuations inside a pressure vessel such as a compressor housing, and that opens when the pressure inside the pressure vessel reaches a preset value, and an air conditioner equipped with the pressure release valve.

The air conditioner according to the present disclosure includes a refrigeration cycle including a refrigerant circuit in which a compressor, an outdoor heat exchanger, a refrigerant pressure reducing device, and an indoor heat exchanger are connected by refrigerant piping, and a pressure release valve provided in the refrigerant circuit and opens when a pressure (P) inside the compressor reaches a preset opening pressure (Pp) to release compressed gas inside the compressor to the outside, wherein when a flow direction of the compressed gas when the compressed gas is released to the outside is defined as a first direction, the pressure release valve includes a partition valve that is arranged upstream in the first direction, contacts an internal space of the compressor, and is subjected to fluctuations in the internal pressure (P) of the compressor during normal operation of the compressor, and a high pressure release valve that is arranged downstream of the partition valve in the first direction and opens when the internal pressure (P) of the compressor reaches the preset opening pressure (Pp), the high pressure release valve and the partition valve are arranged in series along the first direction , and have different static pressure resistance strengths or fatigue strengths due to pressure fluctuations .

The pressure release valve according to the present disclosure is a pressure release valve that is provided in a pressure vessel and opens when the pressure (P) inside the pressure vessel reaches a preset opening pressure (Pp) to release compressed gas inside the pressure vessel to the outside, wherein when a flow direction of the compressed gas when the compressed gas is released to the outside is defined as a first direction, the pressure release valve has a partition valve that is arranged upstream in the first direction, is in contact with the space inside the pressure vessel, and is subjected to fluctuations in the pressure (P) inside the pressure vessel, and a high pressure release valve that is arranged downstream of the partition valve in the first direction and opens when the pressure (P) inside the pressure vessel reaches the preset opening pressure (Pp), and the high pressure release valve and the partition valve are arranged in series along the first direction and have different static pressure resistance strengths or fatigue strengths due to pressure fluctuations .

According to the pressure release valve and air conditioner of the present disclosure, the pressure release valve prevents fatigue failure caused by pressure fluctuations during normal times inside a pressure vessel such as a compressor housing, and can open when the pressure inside the pressure vessel reaches a preset value. This ensures that the pressure release valve opens only when the pressure inside the pressure vessel rises to the preset value, thereby ensuring an open flow path that releases the compressed gas inside the pressure vessel to the outside, and allows the pressure vessel to operate normally without affecting its original functions and performance during normal times.

1 is a refrigerant circuit diagram showing the configuration of an air conditioner 1 according to Embodiment 1. FIG. 3 is an explanatory diagram illustrating the function of a pressure release valve 20 provided in the air conditioner 1 according to the first embodiment. FIG. 1 is a cross-sectional view that shows a schematic diagram of a compressor 2 and a pressure release valve 20 provided in an air conditioner 1 according to Embodiment 1. FIG. 2 is a perspective view showing the configuration of a pressure release valve 20 provided in the air conditioner 1 according to the first embodiment. FIG. 2 is a cross-sectional view showing the configuration of a pressure release valve 20 provided in the air conditioner 1 according to the first embodiment. FIG. 4 is a cross-sectional view showing a modified example of the pressure release valve 20 according to the first embodiment. FIG. 4 is an explanatory diagram showing the fatigue strength characteristics of the pressure relief valve 20. FIG. 4 is an explanatory diagram showing fluctuations in pressure (P) inside a compressor 2. FIG. 4 is a flowchart showing a process flow of a manufacturing method of the pressure release valve 20 according to the first embodiment. 11 is a cross-sectional view showing the configuration of a pressure release valve 20 provided in an air conditioner 1 according to a second embodiment. FIG. 11 is a cross-sectional view showing the configuration of a pressure release valve 20 provided in an air conditioner 1 according to embodiment 3. FIG. 10 is a cross-sectional view showing the configuration of a pressure release valve 20 provided in an air conditioner 1 according to embodiment 4. FIG. 13 is a cross-sectional view showing the configuration of a pressure release valve 20 provided in an air conditioner 1 according to embodiment 5. FIG. 13 is a perspective view showing the configuration of a pressure release valve 20 provided in an air conditioner 1 according to embodiment 6. FIG. 13 is a cross-sectional view showing the configuration of a pressure release valve 20 provided in an air conditioner 1 according to embodiment 6. FIG. 13 is a cross-sectional view showing the configuration of a pressure release valve 20 provided in an air conditioner 1 according to embodiment 7. FIG.

Below, an embodiment of an air conditioner and a pressure release valve according to the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiment, and various modifications are possible without departing from the spirit of the present disclosure. The present disclosure also includes all possible combinations of configurations shown in the following embodiment and its modified examples. In each drawing, the same reference numerals are used to denote the same or equivalent items, and this is common throughout the entire specification. In each drawing, the relative dimensional relationship or shape of each component may differ from the actual ones.

Embodiment 1.
[Configuration of Air Conditioner 1]
FIG. 1 is a refrigerant circuit diagram showing the configuration of an air conditioner 1 according to the first embodiment. As shown in FIG. 1, the air conditioner 1 is a separate type air conditioner consisting of an outdoor unit 1a and an indoor unit 1b. The air conditioner 1 has a refrigeration cycle consisting of a refrigerant circuit in which a compressor 2, a muffler 3, a four-way switching valve 4, an outdoor heat exchanger 5, a refrigerant pressure reducing device 6, a liquid side shutoff valve 7, an indoor heat exchanger 8, and a gas side shutoff valve 9 are connected by a refrigerant piping 10. In addition, an outdoor blower 11 is installed in the outdoor heat exchanger 5 of the outdoor unit 1a, and an indoor blower 12 is installed in the indoor heat exchanger 8 of the indoor unit 1b. Note that the muffler 3, the four-way switching valve 4, the liquid side shutoff valve 7, and the gas side shutoff valve 9 are not necessarily provided in the refrigerant circuit, and may be provided as necessary.

The outdoor unit 1a has a housing (not shown) that houses a compressor 2, a muffler 3, a four-way switching valve 4, an outdoor heat exchanger 5, a refrigerant pressure reducing device 6, a liquid side shut-off valve 7, a gas side shut-off valve 9, an outdoor blower 11, and a control unit 13. The indoor unit 1b has a housing (not shown) that houses an indoor heat exchanger 8, an indoor blower 12, and a control unit 14. The indoor unit 1b is installed in the indoor space to be air-conditioned. On the other hand, the outdoor unit 1a is installed outside the indoor space. Below, a brief explanation of each component of the air conditioner 1 shown in FIG. 1 will be given.

The compressor 2 draws in the refrigerant flowing through the refrigerant pipe 10. The compressor 2 compresses the drawn refrigerant and discharges it into the refrigerant pipe 10. The compressor 2 is, for example, an inverter compressor. When the compressor 2 is an inverter compressor, the operating frequency may be changed arbitrarily by a drive circuit such as an inverter circuit, and the capacity of the compressor 2 that discharges refrigerant per unit time may be changed. In this case, the operation of the drive circuit is controlled by the control unit 13. The refrigerant discharged from the compressor 2 flows into the outdoor heat exchanger 5 or the indoor heat exchanger 8. Specifically, when the air conditioner 1 is performing cooling operation, the refrigerant discharged from the compressor 2 flows into the outdoor heat exchanger 5. On the other hand, when the air conditioner 1 is performing heating operation, the refrigerant discharged from the compressor 2 flows into the indoor heat exchanger 8.

The compressor 2 has a housing 22 (see FIG. 3) made of a pressure vessel. In the first embodiment, a pressure release valve 20 (see FIG. 3) is provided on the upper surface 23 of the housing 22 of the compressor 2. The pressure release valve 20 is a valve that starts opening when the pressure inside the compressor 2 reaches a preset opening pressure (Pp) to release the high-pressure gas inside the compressor 2 to the outside. The installation position of the pressure release valve 20 is not limited to the compressor 2, and may be other locations in the outdoor unit 1a. The configuration of the pressure release valve 20 will be described later. In this disclosure, the high-pressure gas inside the compressor 2 may be called compressed gas.

The outdoor heat exchanger 5 and the indoor heat exchanger 8 exchange heat between the refrigerant flowing inside and the air. The outdoor heat exchanger 5 and the indoor heat exchanger 8 are, for example, fin-and-tube type heat exchangers.

The outdoor heat exchanger 5 exchanges heat between the refrigerant flowing inside and the outdoor air blown by the outdoor blower 11. The outdoor heat exchanger 5 functions as a condenser during cooling operation, condensing and liquefying the refrigerant. The outdoor heat exchanger 5 functions as an evaporator during heating operation, evaporating and vaporizing the refrigerant.

The indoor heat exchanger 8 exchanges heat between the refrigerant flowing inside and the air in the indoor space blown by the indoor blower 12. The indoor heat exchanger 8 functions as an evaporator during cooling operation, evaporating and liquefying the refrigerant. The indoor heat exchanger 8 functions as a condenser during heating operation, condensing and liquefying the refrigerant.

The outdoor blower 11 has a fan motor 11a and a blade portion 11b. Similarly, the indoor blower 12 has a fan motor 12a and a blade portion 12b. The outdoor blower 11 and the indoor blower 12 blow air to the outdoor heat exchanger 5 and the indoor heat exchanger 8, respectively. The rotation speed of the outdoor blower 11 is controlled by the control unit 13, and the rotation speed of the indoor blower 12 is controlled by the control unit 14.

The four-way switching valve 4 is configured to switch between cooling operation, which cools the indoor unit 1b side, and heating operation, which heats the indoor unit 1b side. The four-way switching valve 4 is a flow path switching device that switches the flow of refrigerant depending on whether it is cooling operation or heating operation. When the air conditioner 1 is performing cooling operation, the four-way switching valve 4 connects the discharge port of the compressor 2 to the outdoor heat exchanger 5 and connects the suction port of the compressor 2 to the indoor heat exchanger 8. On the other hand, when the air conditioner 1 is performing heating operation, the four-way switching valve 4 connects the discharge port of the compressor 2 to the indoor heat exchanger 8 and connects the suction port of the compressor 2 to the outdoor heat exchanger 5. The switching operation of the four-way switching valve 4 is performed under the control of the control unit 13.

The refrigerant pressure reducing device 6 reduces the pressure of the refrigerant to expand it. The refrigerant pressure reducing device 6 is, for example, configured as an electronic expansion valve. When the refrigerant pressure reducing device 6 is configured as an electronic expansion valve, the opening degree is adjusted based on a command from the control unit 13. The refrigerant pressure reducing device 6 is provided between the outdoor heat exchanger 5 and the indoor heat exchanger 8.

The muffler 3 is disposed on the discharge side of the compressor 2. In the example of FIG. 1, the muffler 3 is installed between the compressor 2 and the four-way switching valve 4. The muffler 3 serves to suppress the discharge pulsation of the compressor 2. The muffler 3 has a muffler space formed inside, which reduces noise generated by the discharge pulsation of the high-temperature, high-pressure refrigerant gas discharged from the discharge port of the compressor 2. The discharge pulsation increases when the compressor 2 is operating at low speed, so the muffler 3 is particularly effective when the compressor 2 is operating at low speed.

The liquid side shutoff valve 7 is installed between the refrigerant pressure reducing device 6 and the indoor heat exchanger 8. The liquid side shutoff valve 7 is in a fully closed state when pump-down is performed. The opening and closing operation of the liquid side shutoff valve 7 may be performed manually by the operator performing the pump-down, or may be performed based on a command from the control unit 13 via the control unit 13.

The gas-side shutoff valve 9 is installed between the indoor heat exchanger 8 and the compressor 2. The gas-side shutoff valve 9 is fully open when pump-down is performed. The opening and closing operation of the gas-side shutoff valve 9 may be performed manually by the operator performing the pump-down, or may be performed based on a command from the control unit 13 via the control unit 13.

The control unit 13 and the control unit 14 are each composed of, for example, a processor and a memory. In this case, each function of the control unit 13 and the control unit 14 is realized by the processor reading out a pre-stored program from the memory and executing it.

Function of Pressure Relief Valve 20
Before describing the configuration of the pressure release valve 20, the function of the pressure release valve 20 according to embodiment 1 will be described with reference to Figures 2 and 3. Figure 2 is an explanatory diagram for explaining the function of the pressure release valve 20 provided in the air conditioner 1 according to embodiment 1. Figure 3 is a cross-sectional view that typically shows the compressor 2 and the pressure release valve 20 provided in the air conditioner 1 according to embodiment 1.

2, the horizontal axis indicates time, and the vertical axis indicates the pressure P inside the compressor 2. In FIG. 2, the solid line 30 is a graph showing the change in the pressure P inside the compressor 2. However, in FIG. 2, the dashed line 31 indicates the change in the pressure P when the compressor 2 is not provided with a pressure release valve 20, and the dashed line 32 indicates the change in the pressure P when the compressor 2 is provided with a pressure release valve 20. As shown by the solid line 30 in FIG. 2, the change in the pressure P inside the compressor 2 is basically the same up to a certain point, regardless of whether or not the pressure release valve 20 is provided. After that, the change in the pressure P inside the compressor 2 differs due to the action of the pressure release valve 20. This will be explained in detail below.

First, as shown in the example of FIG. 3, the pressure relief valve 20 is provided, for example, on the upper surface 23 of the housing 22 of the compressor 2. In the example of FIG. 3, the pressure relief valve 20 is arranged so that the extension direction of the pressure relief valve 20 faces upward. The pressure relief valve 20 is designed to start opening when the pressure P inside the compressor 2 reaches the opening pressure Pp shown in FIG. 2.

The installation position and extension direction of the pressure release valve 20 on the compressor 2 are not limited to the case of FIG. 3. That is, the pressure release valve 20 may be installed on the side surface 24 of the compressor 2, and in that case, the extension direction of the pressure release valve 20 may be arranged in any direction toward up, down, left, or right. Alternatively, the pressure release valve 20 may be installed on the bottom surface 25 of the compressor 2, and in that case, the extension direction of the pressure release valve 20 may be arranged in any direction toward up, down, left, or right. Alternatively, the pressure release valve 20 may be arranged on the discharge pipe 21 provided at the discharge port of the compressor 2. In addition, since the pressure release valve 20 only needs to be able to release the high-pressure gas to the outside of the refrigerant piping 10, it may be installed not only in the compressor 2 but also at any location in the refrigerant circuit in the outdoor unit 1a. In this way, the installation position and extension direction of the pressure release valve 20 on the compressor 2 can be freely set as appropriate, so the direction in which the high-pressure gas is released from the inside of the refrigerant piping 10 to the outside can be freely set.

The function of the pressure relief valve 20 is explained in detail using Figure 2.

In FIG. 2, Pcomp is the design pressure of compressor 2. The design pressure (Pcomp) is the pressure value to be used as a reference in design calculations of the strength of compressor 2. The design pressure (Pcomp) is set to a value equal to or greater than the maximum pressure that can occur during normal operation of compressor 2. The design pressure (Pcomp) is calculated by multiplying the maximum value of pressure P that can occur during normal operation of compressor 2 by a coefficient of 1 or more (e.g., 1.1). Alternatively, the design pressure (Pcomp) is calculated by adding a certain value (e.g., 0.1 MPa) to the maximum value of pressure P that can occur during normal operation of compressor 2.

In FIG. 2, Pmax is the guaranteed pressure of compressor 2. The guaranteed pressure (Pmax) is a value legally specified based on the design pressure (Pcomp) of compressor 2. The guaranteed pressure (Pmax) is set to a value greater than the design pressure (Pcomp) of compressor 2, based on the law.

In FIG. 2, P'max is the failure pressure of compressor 2. The failure pressure (P'max) is a value that has a tolerance on the high pressure side of the guaranteed pressure (Pmax). In other words, the failure pressure (P'max) is a value that is greater than the guaranteed pressure (Pmax). When the pressure inside compressor 2 exceeds the failure pressure (P'max), the housing 22 of compressor 2 may be damaged. The failure pressure (P'max) is determined by durability experiments on compressor 2, etc.

As explained using FIG. 1, the air conditioner 1 has a compressor 2. The compressor 2 is designed to guarantee a legally stipulated guaranteed pressure (Pmax) based on the design pressure (Pcomp). Therefore, the failure pressure (P'max) of the compressor 2 is greater than the guaranteed pressure (Pmax).

As described above, when the air conditioner 1 is relocated or disposed of, pump-down is performed to recover the refrigerant in the refrigerant pipe 10 to the outdoor unit 1a. When pump-down is performed, the liquid side shutoff valve 7 shown in FIG. 1 is fully closed and the gas side shutoff valve 9 is fully opened to perform forced cooling operation in order to recover the refrigerant in the indoor unit 1b to the outdoor unit 1a. At this time, for example, if the outdoor unit 1a and the indoor unit 1b are already separated and the gas side shutoff valve 9 is fully opened to perform forced cooling operation, a large amount of air will be mixed into the refrigerant pipe 10. As a result, air compression occurs in the compressor 2, and the pressure (P) inside the compressor 2 rises sharply as shown by the solid line 30 in FIG. 2. At this time, as shown by the dashed line 31 in FIG. 2, if the pressure (P) inside the compressor 2 rises further and exceeds the damage pressure (P'max) of the compressor 2, the compressor 2 may be damaged.

Therefore, in the first embodiment, in order to prevent damage to the compressor 2, the outdoor unit 1a is provided with a pressure relief valve 20 that releases high-pressure gas to the outside of the refrigerant circuit. As shown in FIG. 2, when the pressure (P) inside the compressor 2 rises beyond the guaranteed pressure (Pmax) of the compressor 2 and reaches the opening pressure (Pp), the pressure relief valve 20 starts to open. As a result, the high-pressure gas inside the compressor 2 is released to the outside from the pressure relief valve 20, and the pressure (P) inside the compressor 2 drops as shown by the dashed line 32 in FIG. 2. The opening speed of the pressure relief valve 20 is faster than the pressure rise speed until the pressure (P) inside the compressor 2 reaches the damage pressure (P'max) of the compressor 2. Therefore, it is possible to secure a release flow path of the high-pressure gas toward the outside of the refrigerant piping 10 before the pressure (P) reaches the damage pressure (P'max). This makes it possible to prevent damage to the compressor 2.

[Configuration of Pressure Relief Valve 20]
Next, the configuration of the pressure release valve 20 provided in the air conditioner 1 according to the first embodiment will be described with reference to Figures 4 and 5. Figure 4 is a perspective view showing the configuration of the pressure release valve 20 provided in the air conditioner 1 according to the first embodiment. In Figure 4, for the purpose of explanation, a part of the configuration is shown in a see-through manner with broken lines. Figure 5 is a cross-sectional view showing the configuration of the pressure release valve 20 provided in the air conditioner 1 according to the first embodiment.

4 and 5, the pressure relief valve 20 has a cylindrical shape, one end is open, and the other end is covered and closed by the high pressure relief valve 204. When the pressure relief valve 20 is opened, the high pressure gas flows in the direction indicated by the arrow A in FIG. 4 and is released to the outside. Hereinafter, the direction indicated by the arrow A is referred to as the direction in which the high pressure gas flows, or the first direction. In the example of FIG. 4 and FIG. 5, as shown in FIG. 3, the pressure relief valve 20 is disposed on the upper surface 23 of the compressor 2, so the first direction is from the bottom to the top of the paper. However, depending on the installation position of the pressure relief valve 20, the extension direction of the pressure relief valve 20 is not necessarily from the bottom to the top. However, in the following, for the sake of simplicity, the open end of the pressure relief valve 20 will be referred to as the "lower end" and the closed other end of the pressure relief valve 20 will be referred to as the "upper end". The pressure relief valve 20 is made of a metal material such as stainless steel, copper, or a copper alloy.

As shown in FIG. 4, the pressure release valve 20 is composed of a flow path portion 20a and a valve body portion 20b. The flow path portion 20a is composed of a partition valve pipe 201 and a high pressure release valve pipe 203. The valve body portion 20b is composed of a partition valve 202 and a high pressure release valve 204. The partition valve 202 is disposed in the partition valve pipe 201, and the high pressure release valve 204 is disposed in the high pressure release valve pipe 203. The partition valve 202 is connected to the inside of the compressor 2 and is subjected to pressure fluctuations inside the compressor 2. On the other hand, the high pressure release valve 204 is protected by the partition valve 202 and is hardly affected by pressure fluctuations inside the compressor 2. The high pressure release valve 204 starts opening when the pressure (P) inside the compressor 2 reaches the opening pressure (Pp). The configuration of the pressure release valve 20 will be described in detail below.

[Configuration of flow path portion 20a of pressure release valve 20]
First, the flow path 20a of the pressure release valve 20 will be described. As shown in FIG. 5, the partition valve pipe 201 and the high pressure release valve pipe 203 constituting the flow path 20a are connected in series along the axial direction. The central axis of the partition valve pipe 201 and the central axis of the high pressure release valve pipe 203 are aligned, and the flow path 20a has a single cylindrical shape. The partition valve pipe 201 is arranged in the lower stage, and the high pressure release valve pipe 203 is arranged in the upper stage. The partition valve pipe 201 and the high pressure release valve pipe 203 are configured to be integrated. The partition valve pipe 201 and the high pressure release valve pipe 203 are joined by furnace brazing or the like. The size of the outer diameter R1 of the partition valve pipe 201 and the size of the outer diameter R2 of the high pressure release valve pipe 203 are the same. The inner wall of the flow path 20a has a stepped structure in which two steps are formed. Therefore, the plate thickness of the flow passage portion 20a is three types of plate thickness T1, T2, and T3 from the top along the axial direction. The magnitude relationship of the three plate thicknesses T1, T2, and T3 satisfies T1<T2<T3. Therefore, in the flow passage portion 20a, the inner diameter r1 of the lower end portion 201a of the partition valve pipe 201 is smaller than the inner diameter r2 of the upper end portion of the high pressure release valve pipe 203. This will be explained in further detail.

The partition valve pipe 201 has a cylindrical shape, and the inner wall has a stepped structure along the axial direction. One step is formed on the inner wall of the partition valve pipe 201. The lower end 201a of the partition valve pipe 201 is open and communicates with the inside of the compressor 2. The first part 201b on the lower end 201a side of the partition valve pipe 201 has a cylindrical shape with a plate thickness T3. The upper end 201c of the partition valve pipe 201 is open and communicates with the internal space of the high pressure release valve pipe 203. The second part 201d on the upper end 201c side of the partition valve pipe 201 has a cylindrical shape with a plate thickness T2. A step part 201e is provided at the boundary between the first part 201b and the second part 201d of the partition valve pipe 201. The step portion 201e may be disposed in the center of the partition valve pipe 201 in the axial direction, or may be disposed at a position shifted from the center toward the upper end 201c or the lower end 201a. However, the partition valve 202 is disposed in the step portion 201e as shown in FIG. 5. Therefore, the installation position of the step portion 201e may be appropriately set based on the axial length (height size) of the partition valve 202 so that the entire partition valve 202 is accommodated in the partition valve pipe 201. The partition valve 202 is fitted on the second part 201d side of the step portion 201e. Therefore, the lower end of the partition valve 202 is abutted against the step portion 201e, and the partition valve 202 is prevented from falling below the step portion 201e. The step portion 201e also functions as a positioning member indicating the installation position of the partition valve 202. The bulkhead valve 202 and the bulkhead valve pipe 201 are joined by furnace brazing or the like.

The high pressure release valve pipe 203 has a cylindrical shape, and the inner wall has a stepped structure along the axial direction. One step is formed on the inner wall of the high pressure release valve pipe 203. The lower end 203a of the high pressure release valve pipe 203 is open and communicates with the internal space of the second part 201d of the bulkhead valve pipe 201. The first part 203b on the lower end 203a side of the high pressure release valve pipe 203 has a cylindrical shape with a plate thickness T2. The upper end 203c of the high pressure release valve pipe 203 is open and serves as an opening of the pressure release valve 20. The second part 203d on the upper end 203c side of the high pressure release valve pipe 203 has a cylindrical shape with a plate thickness T1. A step part 203e is provided at the boundary between the first part 203b and the second part 203d of the high pressure release valve pipe 203. The step portion 203e may be disposed in the center of the high pressure release valve pipe 203 in the axial direction, or may be disposed at a position shifted from the center toward the upper end 203c or the lower end 203a. However, the high pressure release valve 204 is disposed in the step portion 203e as shown in FIG. 5. Therefore, the installation position of the step portion 203e may be appropriately set based on the axial length (height) of the high pressure release valve 204 so that the entire high pressure release valve 204 is accommodated in the high pressure release valve pipe 203. The high pressure release valve 204 is fitted on the second part 203d side of the step portion 203e. Therefore, the lower end of the high pressure release valve 204 is abutted against the step portion 203e, and the high pressure release valve 204 is prevented from falling below the step portion 203e. The step portion 203e also functions as a positioning member indicating the installation position of the high pressure release valve 204. In addition, the high pressure release valve 204 and the high pressure release valve pipe 203 are joined by furnace brazing or the like. As shown in FIG. 5, the high pressure release valve 204 covers and closes the opening of the pressure release valve 20.

[Configuration of the valve body portion 20b of the pressure release valve 20]
Next, the valve body portion 20b of the pressure relief valve 20 will be described. The valve body portion 20b is composed of a partition valve 202 and a high pressure release valve 204. The partition valve 202 is disposed upstream of the high pressure release valve 204 in the first direction, and is in contact with the space inside the compressor 2. The partition valve 202 is subjected to fluctuations in the pressure (P) inside the compressor 2 during normal operation of the compressor 2. The high pressure release valve 204 is disposed downstream of the partition valve 202 in the first direction, and opens when the pressure (P) inside the compressor 2 reaches a preset opening pressure (Pp).

The partition valve 202 and the high pressure release valve 204 have different static pressure resistance strength and fatigue strength. The static pressure resistance strength of the high pressure release valve 204 is higher than the static pressure resistance strength of the partition valve 202. On the other hand, the fatigue strength of the partition valve 202 is higher than the fatigue strength of the high pressure release valve 204. In the first embodiment, as shown in FIG. 5, the high pressure release valve 204, which has a high static pressure resistance strength, is disposed on the outside side of the compressor 2, and the partition valve 202, which has a high fatigue strength, is disposed on the inside side of the compressor 2. The high pressure release valve 204 and the partition valve 202 are disposed in series along the first direction.

The fatigue strength of the partition valve 202 is higher than that of the high pressure release valve 204. In order to prevent stress concentration, at least the upper surface 202a of the partition valve 202 has a curved shape and is formed into a cap type or dome type. This increases the fatigue strength of the partition valve 202. On the other hand, the plate thickness D1 of the high pressure release valve 204 is thicker than the plate thickness D2 of the partition valve 202. As a result, when the high pressure release valve 204 and the partition valve 202 are made of the same material, the static pressure resistance strength of the high pressure release valve 204 is higher than the static pressure resistance strength of the partition valve 202. The partition valve 202 and the high pressure release valve 204 are made of metal materials such as stainless steel, copper, or copper alloy. In this way, in the first embodiment, the shapes and plate thicknesses of the partition valve 202 and the high pressure release valve 204 are changed to have different static pressure resistance strength and fatigue strength.

The partition valve 202 is constantly exposed to pressure fluctuations inside the compressor 2. However, because the partition valve 202 has high fatigue strength, it has a long endurance time before it is destroyed by fatigue due to pressure fluctuations inside the compressor 2. Therefore, unlike the pressure relief valve described in Patent Document 1, the partition valve 202 does not open at a low pressure level, such as the normal operating range. In addition, the high pressure release valve 204 is located outside the partition valve 202. Therefore, the high pressure release valve 204 is protected by the partition valve 202 and is hardly affected by pressure fluctuations inside the compressor 2. As a result, it is possible to suppress fatigue destruction of the high pressure release valve 204 due to pressure fluctuations inside the compressor 2.

As shown in FIG. 5, in the pressure relief valve 20, a partition valve pipe 201 and a partition valve 202 are arranged on the upstream side in the first direction. Also, a high pressure relief valve pipe 203 and a high pressure relief valve 204 are arranged on the downstream side in the first direction.

Although it has been described that the partition valve 202 is formed in a cap type or a dome type, in more detail, the partition valve 202 is formed in a bottomed cylindrical shape. The partition valve 202 has a closed surface with a closed upper end and an open lower end. However, the upper surface 202a, which is the closed surface of the partition valve 202, is not flat but has a curved shape. The partition valve 202 is formed of a curved thin plate that protrudes in a direction from the inside of the compressor 2 toward the outside of the compressor 2. The curved shape of the partition valve 202 is, for example, a hemispherical shape. In this case, the curved shape of the partition valve 202 has an inner diameter and a radius of curvature that are equal or approximately equal to those of the second part 201d of the partition valve pipe 201. To specifically explain the curved shape of the partition valve 202, the lower end 202c of the partition valve 202 is circular in a plan view. The outer diameter of the circular shape of the lower end 202c is equal to or approximately equal to the inner diameter r3 of the second portion 201d. In addition, since the curved shape of the entire partition valve 202 is a hemispherical shape with a diameter r3, the radius of curvature is equal to or approximately equal to the radius of curvature of the inner wall surface of the second portion 201d. The curved shape of the partition valve 202 is not limited to this case. FIG. 6 is a cross-sectional view showing a modified example of the pressure release valve 20 according to the first embodiment. As shown in FIG. 6, the size of the outer diameter may be the same as the inner diameter r3 of the second portion 201d, and the radius of curvature may be larger than that of the second portion 201d. In this case, the curved shape of the partition valve 202 is a more gentle curved shape than the hemispherical shape, as shown in FIG. 6. In addition, the curved shape of the partition valve 202 has a shorter axial length (i.e., a lower height h1) than the hemispherical shape. The partition valve 202 may be formed in a bottomed tubular shape with the top surface 202a curved and the side surface 202b cylindrical, but the side surface 202b of the partition valve 202 may not be cylindrical. That is, the partition valve 202 may be formed in a spherical shape such as a hemisphere with the bottom end 202c open and the side surface 202b and the top surface 202a both configured with curved shapes. In this case, the curvature of the spherical shape may not be constant and may change gradually along the way. Specifically, for example, the radius of curvature of the side surface 202b and the radius of curvature of the top surface 202a may be different from each other. In the following, the partition valve 202 with a bottomed tubular shape with at least the top surface curved and the partition valve with a spherical shape with an open bottom will be collectively referred to as a cap type or a dome type.

The partition valve 202 is thus formed in a cap or dome shape with an open lower end and at least the upper surface 202a having a curved shape, and the lower end 202c of the partition valve 202 is joined to the inner wall surface of the stepped portion 201e of the partition valve pipe 201 over the entire circumferential length by furnace brazing or the like. Note that, as shown in FIG. 5, no flange or the like is provided on the outer periphery of the partition valve 202. If a flange protruding outward in the horizontal direction were provided, stress would be concentrated on the flange, so the partition valve 202 is intentionally designed not to have a flange.

The partition valve 202 has a curved shape, so stress concentration is small and the rate of decrease in fatigue strength, which is determined by the stress concentration coefficient, is small.

Figure 7 is an explanatory diagram showing the fatigue strength characteristics of the pressure relief valve 20. In Figure 7, the horizontal axis shows the number of times the pressure fluctuation of the compressor 2 is repeated, and the vertical axis shows the stress amplitude. In Figure 7, the black circle 40 shows the stress amplitude that occurs in the pressure relief valve when the partition valve 202 is not provided, the black triangle 41 shows the stress amplitude that occurs in the partition valve 202, and the black star 42 shows the stress amplitude that occurs in the high pressure relief valve 204. In Figure 7, the first threshold Th1 shows the threshold for the number of repetitions required by the product specifications. In Figure 7, the hatched portion shows the area where the valve is destroyed by fatigue.

As shown by the black circle 40 in FIG. 7, when the partition valve 202 is not provided, the pressure release valve will be fatigued and broken when the number of repetitions reaches N1. The number of repetitions N1 is a value smaller than the first threshold value Th1. Therefore, when the partition valve 202 is not provided, the pressure release valve does not have sufficient fatigue strength and fatigue life in terms of the product specifications.

On the other hand, as shown by the black triangle mark 41 in FIG. 7, the partition valve 202 breaks down due to fatigue when the number of repetitions reaches N2. The number of repetitions, N2, is a value greater than the first threshold value Th1. Also, as shown by the black star mark 42 in FIG. 7, at the time when the number of repetitions reaches N2, the high pressure release valve 204 is not affected by the pressure fluctuations of the compressor 2 due to the partition valve 202, so there is almost no stress amplitude. Therefore, it can be seen that the pressure release valve 20 provided with the partition valve 202 and the high pressure release valve 204 has sufficient fatigue strength and fatigue life in terms of the product specifications. In this way, by providing the partition valve 202 with a curved surface shape in the pressure release valve 20 as shown in FIG. 7, it is possible to provide sufficient fatigue strength and fatigue life in terms of the product specifications.

The design pressure (Pmax-s) of the partition valve 202 is equal to or greater than the legally stipulated guaranteed pressure (Pmax) and is less than the opening pressure (Pp) of the high-pressure release valve 204, as shown in Figure 8. Details of Figure 8 will be described later.

The high pressure release valve 204 is formed in a cylindrical shape with a bottom. The high pressure release valve 204 has a closed upper end and an open lower end. However, as shown in FIG. 5, the upper surface 204a, which is the closed surface, of the high pressure release valve 204 is formed in a flat shape. As shown in FIG. 4, the side surface 204d of the high pressure release valve 204 is cylindrical. Therefore, as shown in FIG. 5, the high pressure release valve 204 has a U-shaped cross section in side view. The high pressure release valve 204 is made of a thin metal plate made of the same material as the bulkhead valve 202. Also, as shown in FIG. 5, no flange or the like is provided on the outer periphery of the lower end 204c of the high pressure release valve 204. If a flange protruding outward in the horizontal direction were provided, stress would be concentrated on the flange, so the high pressure release valve 204 is intentionally configured not to have a flange.

The plate thickness D1 of the high pressure release valve 204 is thicker than the plate thickness D2 of the partition valve 202. In other words, the relationship D1>D2 is satisfied. In addition, the plate thickness D1 of the high pressure release valve 204 is thinner than any of the plate thicknesses T1, T2, and T3 of the flow passage portion 20a. In other words, the relationship D1<T1<T2<T3 is satisfied.

Figure 8 is an explanatory diagram showing the fluctuations in pressure (P) inside the compressor 2. Figure 8 shows the graph of Figure 2 in more detail. In Figure 8, the horizontal axis shows time, and the vertical axis shows pressure (P). In Figure 8, dashed line 31 shows the change in pressure (P) when the compressor 2 is not provided with a pressure relief valve 20, and dashed line 32 shows the change in pressure (P) when the compressor 2 is provided with a pressure relief valve 20. In addition, solid line 33 shows the pressure fluctuations inside the compressor 2 when the compressor 2 is operating normally.

In the first embodiment, when the compressor 2 is operating normally, the pressure (P) of the contents of the compressor 2 fluctuates within a relatively small range, as shown by the solid line 33 in FIG. 8. The pressure fluctuations are received by the bulkhead valve 202, and the high-pressure release valve 204 is hardly affected by the pressure fluctuations.

When a large amount of air enters the refrigerant piping 10 due to pump-down or the like, the air is compressed inside the compressor 2. In that case, as shown by the solid line 30 in FIG. 8, the pressure (P) inside the compressor 2 rises. Then, when the pressure (P) inside the compressor 2 exceeds the guaranteed pressure (Pmax) of the compressor 2 and reaches the design pressure (Pmax-s) of the partition valve 202, the partition valve 202 opens. That is, the partition valve 202 is damaged. Furthermore, when the pressure (P) inside the compressor 2 rises and reaches the opening pressure (Pp) of the pressure release valve 20, the high pressure release valve 204 starts to open. That is, the high pressure release valve 204 starts to break. At this time, the opening speed of the high pressure release valve 204 is faster than the pressure rise speed until the pressure (P) inside the compressor 2 reaches the damage pressure (P'max) of the compressor 2. Therefore, before the pressure (P) reaches the damage pressure (P'max), the high pressure release valve 204 opens, and the inside and outside of the housing 22 of the compressor 2 are connected. This allows the high pressure gas to be released from the high pressure release valve 204 to the outside. As a result, as shown by the dashed line 32 in Figure 8, the pressure (P) inside the compressor 2 drops suddenly. This makes it possible to prevent damage to the compressor 2.

The plate thicknesses T1, T2, and T3 of the flow passage portion 20a of the pressure release valve 20 are thicker than the plate thicknesses D1 and D2 of the valve body portion 20b. Therefore, the static pressure resistance strength of the flow passage portion 20a is higher than the static pressure resistance strength of the valve body portion 20b. Therefore, even if the pressure release valve 20 opens and a large amount of refrigerant gas flows toward the pressure release valve 20, causing the pressure of the refrigerant gas in the flow passage portion 20a to increase, the shape of the flow passage portion 20a can be maintained. This makes it possible to avoid an increase in pressure loss in the flow passage portion 20a.

[Method of Manufacturing Pressure Relief Valve 20]
Next, a description will be given of a method for manufacturing the pressure release valve 20. Fig. 9 is a flow chart showing the flow of processes in the method for manufacturing the pressure release valve 20 according to the first embodiment.

Because the inner wall of the partition valve pipe 201 has a stepped structure, the inner diameter r3 of the upper end 201c of the partition valve pipe 201 is larger than the inner diameter r1 of the lower end 201a. Therefore, in step S1, the partition valve 202 is inserted into the partition valve pipe 201 starting from the upper end 201c, which has the larger inner diameter (opening diameter). When the lower end 202c of the partition valve 202 abuts against the step of the step portion 201e, the step portion 201e prevents further insertion.

The inner diameter r2 of the upper end 203c of the high pressure release valve pipe 203 is larger than the inner diameter r3 of the lower end 203a. Therefore, in step S2, the high pressure release valve 204 is inserted into the high pressure release valve pipe 203 starting from the upper end 203c, which has the larger inner diameter (opening diameter). When the lower end 204c of the high pressure release valve 204 abuts against the step of the step portion 203e, the step portion 203e prevents further insertion. Note that the order of steps S1 and S2 may be reversed.

Next, in step S3, the partition valve pipe 201 with the partition valve 202 inserted therein and the high pressure release valve pipe 203 with the high pressure release valve 204 inserted therein are joined by furnace brazing or the like. At this time, brazing is performed while the relative positions of the partition valve 202 and the high pressure release valve 204 are maintained by the step portions 201e and 203e provided in the flow path portion 20a. This joins the partition valve pipe 201 and the high pressure release valve pipe 203. At the same time, the partition valve pipe 201 and the partition valve 202 are joined, and the high pressure release valve pipe 203 and the high pressure release valve 204 are joined. When the partition valve pipe 201 and the partition valve 202 are joined, the lower end portion 202c of the partition valve 202 is joined to the upper surface of the step of the step portion 201e. Alternatively, at the same time, at least a portion of the side surface 202b of the partition valve 202 may be joined to the inner wall of the step portion 201e. Similarly, when the high pressure release valve pipe 203 and the high pressure release valve 204 are joined, the lower end portion 204c of the high pressure release valve 204 is joined to the upper surface of the step of the step portion 203e. Alternatively, at the same time, at least a portion of the side surface 204d of the high pressure release valve 204 may be joined to the inner wall of the step portion 203e.

Through the above steps, the pressure release valve 20 is manufactured.

As described above, in the first embodiment, the outdoor unit 1a is provided with a pressure release valve 20 in preparation for the occurrence of a diesel explosion during pump-down. The pressure release valve 20 also includes a bulkhead valve 202 with high fatigue strength and a high-pressure release valve 204 with high static pressure resistance. The high-pressure release valve 204 opens only when a large amount of air is mixed into the refrigerant piping 10, air compression occurs in the compressor 2, and the pressure (P) in the compressor 2 rises rapidly and exceeds the guaranteed pressure (Pmax). This ensures an open flow path that releases high-pressure gas toward the outside of the refrigerant piping 10, and damage to the compressor 2 can be prevented. During normal operation of the compressor 2, the bulkhead valve 202 with high fatigue strength protects the high-pressure release valve 204 by receiving pressure fluctuations inside the compressor 2, so that fatigue failure of the high-pressure release valve 204 can be prevented. Therefore, during normal operation, the compressor 2 can operate well without affecting its original functions and performance.

Embodiment 2.
10 is a cross-sectional view showing the configuration of the pressure release valve 20 provided in the air conditioner 1 according to embodiment 2. The difference between embodiment 2 and embodiment 1 is that in embodiment 2, a positioning portion consisting of convex portions 203f and 201f is provided on the joint surface between the partition valve pipe 201 and the high pressure release valve pipe 203. The other configurations are the same as those in embodiment 1, so the description thereof will be omitted here.

As shown in FIG. 10, the bulkhead valve pipe 201 and the high-pressure release valve pipe 203 that constitute the flow path 20a of the pressure release valve 20 are joined by brazing or the like. At this time, in order to position the bulkhead valve pipe 201 and the high-pressure release valve pipe 203 that constitute the flow path 20a, convex parts 203f and 201f are provided on a part of the joining surface in advance.

In the example of FIG. 10, a convex portion 201f is provided on a portion of the upper end portion 201c of the partition valve pipe 201, which is one of the joint surfaces. As shown in FIG. 10, the convex portion 201f is disposed near the inner wall of the flow path portion 20a. The convex portion 201f may be provided over the entire circumferential length of the upper end portion 201c, but since it is only necessary to position it in the radial direction, it may be provided at only one location in the circumferential direction of the upper end portion 201c. Alternatively, the convex portion 201f may be provided at two opposing locations in the circumferential direction of the upper end portion 201c.

In the example of FIG. 10, a convex portion 203f is provided on a part of the lower end portion 203a of the high pressure release valve pipe 203, which is another one of the joint surfaces. As shown in FIG. 10, the convex portion 203f is arranged near the outer wall of the flow path portion 20a. The convex portion 203f may be provided over the entire circumferential length of the lower end portion 203a, but may be provided at one or two circumferential locations of the lower end portion 203a as long as it can be positioned. However, in either case, the convex portion 203f is arranged at a position corresponding to the convex portion 201f. Since the convex portion 203f is arranged near the outer wall of the lower end portion 203a, the portion 203aa near the inner wall of the lower end portion 203a is a concave portion (female portion) that is concave toward the first direction relative to the convex portion 203f. The concave portion (female portion) has a complementary shape to the convex portion 201f (male portion).

When joining the bulkhead valve pipe 201 and the high pressure release valve pipe 203, as shown in FIG. 10, the convex portion 201f is fitted to the radially inner side of the convex portion 203f arranged on the outside. That is, the convex portion 201f (male portion) is fitted to the part 203aa (female portion) near the inner wall of the lower end portion 203a, which is a recess. In this way, one of the convex portions 203f and 201f functions as a male portion, and the other functions as a female portion that receives the male portion. In this case, the part 203aa near the inner wall of the lower end portion 203a functions as a female portion, and the convex portion 201f functions as a male portion. In this way, by fitting the male portion and the female portion, the bulkhead valve pipe 201 and the high pressure release valve pipe 203 can be positioned in the axial direction and the radial direction. This makes it possible to prevent axial and radial misalignment between the bulkhead valve pipe 201 and the high pressure release valve pipe 203.

Note that while FIG. 10 shows a case where both convex portion 203f and convex portion 201f are provided, only one of convex portion 203f and convex portion 201f may be provided. That is, the convex portion may be provided on only one of upper end portion 201c and lower end portion 203a. In that case, a complementary recess or insertion hole into which the convex portion is inserted is disposed on the other of upper end portion 201c and lower end portion 203a. In this case, the convex portion becomes the male portion, and the recess or insertion hole becomes the female portion.

As described above, in the second embodiment, as in the first embodiment, the outdoor unit 1a of the air conditioner 1 is provided with a pressure release valve 20, and therefore the same effects as in the first embodiment can be obtained.

In the second embodiment, a positioning portion is provided on the joining surface when joining the partition valve pipe 201 and the high pressure release valve pipe 203 that constitute the flow path portion 20a, for performing axial and radial positioning. The positioning portion is composed of a male portion provided on one of the joining surfaces when joining the partition valve pipe 201 and the high pressure release valve pipe 203, and a female portion provided on the other of the joining surfaces and having a complementary shape to the male portion. This makes it easy to perform axial positioning and radial positioning between the partition valve pipe 201 and the high pressure release valve pipe 203. Since positioning is thus made easy, the assembly work of the high pressure release valve 204 and the partition valve 202 is made easy. This allows the high pressure release valve 204 and the partition valve 202 to be manufactured and stored individually. In addition, the strength characteristics of the high pressure release valve 204 and the partition valve 202 can be appropriately selected according to the pressure characteristics of the compressor 2 to which the pressure release valve 20 is attached, so that the pressure release valve 20 can be manufactured easily with high accuracy.

Embodiment 3.
11 is a cross-sectional view showing the configuration of the pressure release valve 20 provided in the air conditioner 1 according to embodiment 3. The difference between embodiment 3 and embodiment 1 is that in embodiment 3, the inner diameter of the high pressure release valve pipe 203 is enlarged, and at least a part of the downstream end of the partition valve pipe 201 is inserted and joined to the upstream end of the high pressure release valve pipe 203. The other configuration is the same as in embodiment 1, so a description thereof will be omitted here.

In the third embodiment, as shown in FIG. 11, a portion 203g on the lower end 203a side of the first portion 203b of the high pressure release valve pipe 203 is processed to widen its inner diameter. As a result, the inner diameter r4 of the portion 203g is equal to the outer diameter R1 of the partition valve pipe 201. On the other hand, the outer diameter R3 of the portion 203g is naturally larger than the outer diameter R1 of the partition valve pipe 201. In addition, the plate thickness of the portion 203g is the same as the plate thickness T2 of the first portion 203b of the high pressure release valve pipe 203.

Therefore, at least a part of the second part 201d of the partition valve pipe 201 is inserted into the part 203g in the direction of the arrow B. After the insertion, the high pressure release valve pipe 203 and the partition valve pipe 201 are joined by furnace brazing or the like.

As described above, in the third embodiment, as in the first embodiment, a pressure release valve 20 is provided in the outdoor unit 1a of the air conditioner 1, and therefore the same effects as in the first embodiment can be obtained.

In addition, in the third embodiment, the inner diameter of the high pressure release valve pipe 203 is enlarged, and a portion of the partition valve pipe 201 is inserted into and joined to the high pressure release valve pipe 203. This allows the high pressure release valve 204 and the partition valve 202 to be manufactured and stored separately. Furthermore, the strength characteristics of the high pressure release valve 204 and the partition valve 202 can be appropriately selected according to the pressure characteristics of the compressor 2 to which the pressure release valve 20 is attached, allowing the pressure release valve 20 to be manufactured with high precision.

Embodiment 4.
12 is a cross-sectional view showing the configuration of the pressure release valve 20 provided in the air conditioner 1 according to embodiment 4. The difference between embodiment 4 and embodiment 1 is that in embodiment 4, the high pressure release valve 204 and the partition wall valve 202 have the same shape, but are made of different materials for the high pressure release valve 204 and the partition wall valve 202. The other configuration is the same as in embodiment 1, so a description thereof will be omitted here.

In the above embodiments 1 to 3, the difference in static pressure resistance and fatigue strength between the high pressure release valve 204 and the partition valve 202 is achieved by the difference in the shapes of the high pressure release valve 204 and the partition valve 202. In embodiment 4, the static pressure resistance of the high pressure release valve 204 is increased and the fatigue strength of the partition valve 202 is increased by changing the materials used for the high pressure release valve 204 and the partition valve 202.

In general, aluminum alloys have a higher fatigue strength than copper or copper alloys, so the bulkhead valve 202 is made of, for example, an aluminum alloy. Also, copper has a higher static pressure resistance than aluminum, so the high-pressure release valve 204 is made of copper. Thus, in the fourth embodiment, the bulkhead valve 202 is made of a metal with high fatigue strength, and the high-pressure release valve 204 is made of a metal with high static pressure resistance.

In addition, if the plate thickness D2 of the partition valve 202 and the plate thickness D1 of the high pressure release valve 204 are equal, the partition valve 202 may be made of a material having a lower tensile strength than the high pressure release valve 204.

In addition, in the fourth embodiment, an example was described in which the high pressure release valve 204 and the partition valve 202 have the same shape, but this is not the only case, and the shapes of the high pressure release valve 204 and the partition valve 202 may be the same as those of the first to third embodiments. Even in this case, by using different materials for the high pressure release valve 204 and the partition valve 202, the fatigue strength of the partition valve 202 is further increased, and the static pressure resistance strength of the high pressure release valve 204 is increased.

As described above, in the fourth embodiment, as in the first embodiment, the outdoor unit 1a of the air conditioner 1 is provided with a pressure release valve 20 composed of a bulkhead valve 202 with high fatigue strength and a high-pressure release valve 204 with high static pressure resistance, so that the same effects as in the first embodiment can be obtained.

In addition, in the fourth embodiment, the high pressure release valve 204 and the partition valve 202 are made of different materials, so that the strength characteristics of the high pressure release valve 204 and the partition valve 202 can be appropriately selected to manufacture the pressure release valve 20 with high precision. This allows the pressure release valve 20 to be manufactured easily and at low manufacturing costs without increasing the machining precision of the high pressure release valve 204, the partition valve 202, and the parts to which they are attached.

Embodiment 5.
13 is a cross-sectional view showing the configuration of the pressure release valve 20 provided in the air conditioner 1 according to embodiment 5. The difference between embodiment 5 and embodiment 1 is that in embodiment 5, the space 20c between the high pressure release valve 204 and the partition wall valve 202 is made into a sealed structure, and a gas with a pressure higher than the atmospheric pressure of the surrounding environment in which the air conditioner 1 is installed is sealed in the space 20c. The other configurations are the same as those in embodiment 1, so a description thereof will be omitted here.

As shown in FIG. 13, in the fifth embodiment, the space 20c between the high pressure release valve 204 and the partition valve 202 in the flow path 20a is made to have a sealed structure. In addition, when the pressure release valve 20 is manufactured, the gas 205 is sealed in the space 20c at a preset pressure. Therefore, the pressure of the gas 205 is higher than the atmospheric pressure of the surrounding environment in which the air conditioner 1 is installed. The gas 205 is, for example, an inert gas. This can reduce the average stress of the partition valve 202 of the pressure release valve 20 and increase the fatigue strength of the partition valve 202.

The inert gas used as gas 205 is a gas made of a material that does not cause chemical reactions such as corrosion even when it comes into contact with the pressure release valve 20.

As described above, in the fifth embodiment, as in the first embodiment, a pressure release valve 20 is provided in the outdoor unit 1a of the air conditioner 1, and therefore the same effects as in the first embodiment can be obtained.

In addition, in the fifth embodiment, the space 20c between the high pressure release valve 204 and the partition valve 202 in the flow path 20a is sealed to seal in the gas 205. This reduces the average stress of the partition valve 202 of the pressure release valve 20, and increases the fatigue strength of the partition valve 202.

Embodiment 6.
Fig. 14 is a perspective view showing the configuration of the pressure release valve 20 provided in the air conditioner 1 according to embodiment 6. In Fig. 14, for the purpose of explanation, a part of the configuration is shown in a see-through manner with dashed lines. Fig. 15 is a cross-sectional view showing the configuration of the pressure release valve 20 provided in the air conditioner 1 according to embodiment 6. The difference between embodiment 6 and embodiment 1 is that in embodiment 6, a notch 204b is provided on the upper surface 204a of the high pressure release valve 204. As the other configurations are the same as those in embodiment 1, explanations thereof will be omitted here.

As shown in Figures 14 and 15, in the sixth embodiment, a notch 204b is provided on the upper surface 204a of the high pressure release valve 204. The notch 204b is formed in the center of the upper surface 204a of the high pressure release valve 204. The width of the notch 204b is, for example, about 0.1 mm. The depth of the notch 204b is, for example, about 1/10 of the plate thickness D1 of the upper surface 204a of the high pressure release valve 204.

The shape of the notch 204b is X-shaped in plan view as shown in FIG. 14. That is, two linear notches are formed and they intersect with each other. The two linear notches may be perpendicular to each other or may intersect at a certain angle.

In the entire upper surface 204a of the high pressure release valve 204, the notch 204b has a thinner plate thickness than other parts of the upper surface 204a of the high pressure release valve 204, so the static pressure resistance strength is weaker. Therefore, when the high pressure release valve 204 opens (i.e., breaks), the high pressure release valve 204 breaks from the notch 204b. In this way, by providing the notch 204b in the high pressure release valve 204, the strength and opening shape of the high pressure release valve 204 when it opens (i.e., breaks) can be controlled. Therefore, it is possible to prevent the compressor 2 from breaking due to the time it takes for the high pressure release valve 204 to open. In addition, since the opening of the high pressure release valve 204 starts from the notch 204b, the opening shape and opening area required for releasing the high pressure gas can be reliably secured.

Instead of providing the notch 204b in the high pressure release valve 204, a thickness distribution is configured on the upper surface 204a of the high pressure release valve 204 during drawing. Specifically, the thickness D1 is not made uniform on the upper surface 204a of the high pressure release valve 204, but the thickness of a portion of the upper surface 204a is made thinner than the other portions. The thinner portion has weaker static pressure resistance than the other portions of the upper surface 204a of the high pressure release valve 204. In this way, a thickness distribution is configured so that the thickness of a portion of the upper surface 204a is thinner than the other portions, and the same effect as the notch 204b can be achieved by this thickness distribution.

As described above, in the sixth embodiment, as in the first embodiment, a pressure release valve 20 is provided in the outdoor unit 1a of the air conditioner 1, and therefore the same effects as in the first embodiment can be obtained.

In addition, in the sixth embodiment, the plate thickness of the upper surface 204a of the high pressure release valve 204 is partially thinned by providing a notch 204b on the upper surface 204a of the high pressure release valve 204. Therefore, when the high pressure release valve 204 opens (i.e., breaks), the high pressure release valve 204 breaks from the portion of the notch 204b. In this way, by providing the notch 204b on the high pressure release valve 204, the strength and opening shape of the high pressure release valve 204 when it is open can be controlled, so that a release flow path for the high pressure gas can be reliably secured.

Embodiment 7.
16 is a cross-sectional view showing the configuration of the pressure release valve 20 provided in the air conditioner 1 according to embodiment 7. The difference between embodiment 7 and embodiment 1 is that embodiment 7 is provided with a strain measuring unit 206 that measures the strain of the upper surface 204a of the high pressure release valve 204. The other configuration is the same as embodiment 1, so a description thereof will be omitted here.

The bulkhead valve 202 is destroyed before the high pressure release valve 204 due to metal fatigue and other causes. If the bulkhead valve 202 is destroyed while the compressor 2 can continue to operate, the pressure applied to the deformation amount of the high pressure release valve 204 increases, and the strain of the high pressure release valve 204 increases. Therefore, in the seventh embodiment, in order to measure the strain of the upper surface 204a of the high pressure release valve 204, as shown in FIG. 16, a strain measurement unit 206 is provided in the high pressure release valve 204. It is desirable that the strain measurement unit 206 is installed on the upper surface 204a of the high pressure release valve 204. In addition, the strain measurement unit 206 is composed of, for example, a strain gauge. The strain measurement unit 206 is installed on the upper surface 204a of the high pressure release valve 204 when the air conditioner 1 is installed, and constantly measures the strain of the high pressure release valve 204. The measurement results are stored in the memory of the control unit 13 as time series data. The control unit 13 determines that the partition valve 202 is destroyed when the measured strain of the high pressure release valve 204 exceeds a preset threshold value Th2 based on the measurement result of the strain measurement unit 206. Alternatively, the control unit 13 calculates the increase rate of the strain of the high pressure release valve 204 over a certain period of time based on the time series data, and determines that the partition valve 202 is destroyed when the increase rate exceeds a preset threshold value Th3.

In this way, by measuring the strain of the high pressure release valve 204, it is possible to determine whether the partition valve 202 installed in the pressure release valve 20 is broken or not. If the partition valve 202 is broken, it is assumed that the strength of the housing 22 of the compressor 2 is also degraded. Therefore, when the control unit 13 determines that the cumulative operating time of the air conditioner 1 exceeds the preset threshold value Th4 and that the partition valve 202 is broken, it presents a message to the user urging the user to replace the compressor 2. In addition, when the control unit 13 determines that the cumulative operating time of the air conditioner 1 exceeds the preset threshold value Th4 and that the partition valve 202 is broken, it may stop the operation of the air conditioner 1. Note that the control unit 13 may both present a message and stop the operation of the air conditioner 1, or may perform only one of them.

In this way, the lifespan of the housing 22 of the compressor 2 can be predicted from the presence or absence of destruction of the partition valve 202. Therefore, in the seventh embodiment, a strain measurement unit 206 is provided to determine the presence or absence of destruction of the partition valve 202 based on the measurement results. Then, when the partition valve 202 is destroyed and the accumulated operating time of the air conditioner 1 exceeds the threshold value Th4, the user can be notified that the lifespan of the compressor 2 is approaching. This makes it possible to urge the user to replace the compressor 2 or the air conditioner 1 before the compressor 2 is destroyed.

In the seventh embodiment, when the notch 204b shown in the sixth embodiment is provided on the upper surface 204a of the high pressure release valve 204, the strain measuring unit 206 is installed to avoid the notch 204b. In this case, there is a possibility that the strain measurement result will be deviated compared to when the strain measuring unit 206 is provided in the center of the upper surface 204a of the high pressure release valve 204. Therefore, the deviation is obtained in advance by an experiment or the like, and the control unit 13 compensates for the strain measurement result based on the deviation.

As described above, in the seventh embodiment, as in the first embodiment, a pressure release valve 20 is provided in the outdoor unit 1a of the air conditioner 1, and therefore the same effects as in the first embodiment can be obtained.

In addition, in the seventh embodiment, the high pressure release valve 204 is provided with a strain measuring unit 206. The control unit 13 can determine whether or not the partition valve 202 is broken based on the measurement results of the strain measuring unit 206. Furthermore, the control unit 13 can predict the lifespan of the housing 22 of the compressor 2 from whether or not the partition valve 202 is broken. This makes it possible to urge the user to replace the compressor 2 or the air conditioner 1 before the compressor 2 is broken.

1 air conditioner, 1a outdoor unit, 1b indoor unit, 2 compressor, 3 muffler, 4 four-way switching valve, 5 outdoor heat exchanger, 6 refrigerant pressure reducing device, 7 liquid side shutoff valve, 8 indoor heat exchanger, 9 gas side shutoff valve, 10 refrigerant piping, 11 outdoor blower, 11a fan motor, 11b blade portion, 12 indoor blower, 12a fan motor, 12b blade portion, 13 control unit, 14 control unit, 20 pressure release valve, 20a flow path portion, 20b valve body portion, 20c space, 21 discharge pipe, 22 housing, 23 top surface, 24 side surface, 25 bottom surface, 30 solid line, 31 dashed line, 32 dashed line, 33 solid line, 40 black circle mark, 41 black triangle mark, 42 black star mark, 201 Pipe for bulkhead valve, 201a lower end, 201b first part, 201c upper end, 201d second part, 201e step part, 201f convex part, 202 bulkhead valve, 202a upper surface, 202b side part, 202c lower end, 203 pipe for high pressure release valve, 203a lower end, 203aa part, 203b first part, 203c upper end, 203d second part, 203e step part, 203f convex part, 203g part, 204 high pressure release valve, 204a upper surface, 204b notch part, 204c lower end, 204d side part, 205 gas, 206 strain measurement part.

Claims (13)

a refrigeration cycle including a refrigerant circuit in which a compressor, an outdoor heat exchanger, a refrigerant pressure reducing device, and an indoor heat exchanger are connected by refrigerant piping;
a pressure relief valve that is provided in the refrigerant circuit and opens when the pressure (P) inside the compressor reaches a preset opening pressure (Pp) to release the compressed gas inside the compressor to the outside,
When a flow direction of the compressed gas when the compressed gas is released to the outside is defined as a first direction,
The pressure relief valve is
a partition valve disposed upstream in the first direction, in contact with an internal space of the compressor, and subjected to fluctuations in pressure (P) inside the compressor during normal operation of the compressor;
a high pressure release valve that is disposed downstream of the partition valve in the first direction and opens when the pressure (P) inside the compressor reaches a preset opening pressure (Pp),
The high pressure release valve and the partition valve are arranged in series along the first direction , and have different static pressure resistance strengths or fatigue strengths due to pressure fluctuations .
Air conditioner. The diaphragm valve is
a pressure relief valve disposed upstream of the high pressure relief valve in the first direction, the pressure relief valve being subjected to fluctuations in the pressure (P) inside the compressor during normal operation when the pressure (P) inside the compressor is equal to or lower than a design pressure (Pcomp) of the compressor;
The high pressure relief valve is
The opening pressure (Pp) is set to a value that is greater than the guaranteed pressure (Pmax) of the compressor legally defined based on the design pressure (Pcomp) of the compressor and less than the damage pressure (P'max) at which the compressor is damaged.
The air conditioner according to claim 1. a refrigeration cycle including a refrigerant circuit in which a compressor, an outdoor heat exchanger, a refrigerant pressure reducing device, and an indoor heat exchanger are connected by refrigerant piping;
a pressure relief valve that is provided in the refrigerant circuit and opens when the pressure (P) inside the compressor reaches a preset opening pressure (Pp) to release the compressed gas inside the compressor to the outside;
Equipped with
When a flow direction of the compressed gas when the compressed gas is released to the outside is defined as a first direction,
The pressure relief valve is
a partition valve disposed upstream in the first direction, in contact with an internal space of the compressor, and subjected to fluctuations in pressure (P) inside the compressor during normal operation of the compressor;
a high pressure release valve that is disposed downstream of the partition valve in the first direction and opens when the pressure (P) inside the compressor reaches a preset opening pressure (Pp);
having
the high pressure relief valve and the partition valve are arranged in series along the first direction;
The high pressure release valve and the partition valve have different static pressure resistance and fatigue strength due to pressure fluctuation .
Air conditioner. The high pressure release valve has a static pressure resistance greater than that of the bulkhead valve,
The diaphragm valve has a higher fatigue strength than the high pressure relief valve.
The air conditioner according to claim 3. the high pressure release valve is a valve having one end on a downstream side in the first direction that is closed and one end on an upstream side in the first direction that is open, a closing surface constituting the closed downstream end has a planar shape,
The partition valve is a valve having one end on a downstream side in the first direction that is closed and one end on an upstream side in the first direction that is open, and a closing surface constituting the closed downstream end has a curved shape.
The air conditioner according to any one of claims 1 to 4. a cutout is provided on the closing surface of the high pressure relief valve;
The air conditioner according to claim 5. A strain measuring unit that measures a strain of the blocking surface is provided on the blocking surface of the high pressure release valve.
7. The air conditioner according to claim 5 or 6. The partition valve is disposed inside a cylindrical partition valve pipe that supports the partition valve,
The partition valve is joined to an inner wall of the partition valve pipe,
The high pressure relief valve is disposed inside a cylindrical high pressure relief valve pipe that supports the high pressure relief valve,
The high pressure relief valve is joined to the inner wall of the high pressure relief valve pipe,
The high pressure release valve pipe and the partition valve pipe are arranged in series along the first direction so that their axial directions coincide with each other, and are joined to each other.
An air conditioner according to any one of claims 1 to 7. a positioning portion for performing axial and radial positioning is provided on a joining surface when joining the partition valve pipe and the high pressure release valve pipe,
The positioning portion is
a male portion provided on either one of a joint surface of the partition wall valve pipe side and a joint surface of the high pressure release valve pipe side;
a female portion provided on the other of the joint surface on the partition valve pipe side and the joint surface on the high pressure release valve pipe side, the female portion having a complementary shape to the male portion.
The air conditioner according to claim 8. At least a portion of the downstream end of the partition valve pipe is inserted and joined to the upstream end of the high pressure release valve pipe.
The air conditioner according to claim 8. In a flow path portion constituted by the high pressure release valve pipe and the partition valve pipe, a space formed between the high pressure release valve and the partition valve is sealed.
The air conditioner according to any one of claims 8 to 10. The space formed between the high pressure release valve and the partition valve is filled with gas at a pressure higher than the atmospheric pressure of the surrounding environment in which the air conditioner is installed.
The air conditioner according to claim 11. A pressure relief valve that is provided in a pressure vessel and opens when the pressure (P) inside the pressure vessel reaches a preset opening pressure (Pp) to release compressed gas inside the pressure vessel to the outside,
When a flow direction of the compressed gas when the compressed gas is released to the outside is defined as a first direction,
The pressure relief valve is
a partition valve disposed upstream in the first direction, in contact with an internal space of the pressure vessel, and subjected to fluctuations in pressure (P) inside the pressure vessel;
a high pressure release valve that is disposed downstream of the partition valve in the first direction and opens when the pressure (P) inside the pressure vessel reaches a preset opening pressure (Pp);
The high pressure release valve and the partition valve are arranged in series along the first direction , and have different static pressure resistance strengths or fatigue strengths due to pressure fluctuations .
Pressure relief valve.

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