JPH10176869A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high reliable refrigeration cycle device in which an excessive load can be prevented from being applied to a compressor due to an excessive operation capacity without using any variable capacity type compressor. SOLUTION: There are provided a bypass passage E arranged while a first branch section C and a second branch section D in a refrigerant circuit 1 are being connected, an auxiliary heat exchanger 10 arranged at the bypass passage E, and a second throttle device 9 arranged at the bypass passage E between the first branch section C and the auxiliary heat exchanger 10. Then, in the case that a total operating capacity of the compressor being operated in a plurality of compressors A and B is excessive against a load at the utilization side, the refrigerant is branched to flow to the bypass passage E and evaporated or condensed at the auxiliary heat exchanger 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of connecting a plurality of constant capacity compressors connected in parallel, a heat source side heat exchanger, a first expansion device, and a use side heat exchanger by piping. The present invention relates to a refrigeration cycle apparatus including a refrigerant circuit, and configured to control the number of operating compressors in accordance with a use-side load.

[0002]

2. Description of the Related Art Conventionally, a refrigerating cycle device such as an air conditioner or a refrigerating device in which a plurality of constant capacity compressors having different capacities or the same capacity are connected in parallel and used in a refrigerant circuit. Has performed control (hereinafter, referred to as "operating number control") for changing the operating number of the compressors according to a use side load (for example, an air conditioning load) that changes as needed.

FIG. 18 shows an example of conventional control of the number of operating units using two compressors, a constant capacity compressor A and a constant capacity compressor B having a larger capacity than the compressor A. When the load on the use side is minimum, only the compressor A is operated. When the load on the use side is increased to some extent, only the compressor B is operated. When the load on the use side is further increased, both the compressor A and the compressor B are operated. When the operation number control
4 shows the relationship between the use side load and the total operating capacity of the compressor.

[0004]

However, in the conventional operation number control as shown in FIG. 18, the utilization side load changes steplessly, whereas the total operating capacity of the compressor changes stepwise. As shown by the shaded area in FIG. 18, the total operating capacity of the compressor sometimes became excessive with respect to the use-side load. When the operating capacity becomes excessive in this way, for example, during the cooling operation, the suction pressure of the compressor decreases, and during the heating operation, the discharge pressure of the compressor excessively increases. An unreasonable load was applied, resulting in damage to the compressor.

If a variable displacement compressor using an inverter is used as the compressor, the relationship between the load on the user side and the operating capacity of the compressor can be linearly controlled as shown in FIG.
While it is possible to prevent an unreasonable load from being applied to the compressor, adverse effects such as a loss of compressor operation efficiency and harmonic noise caused by the inverter, which has recently been regarded as a problem, have occurred.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an excessive load is applied to a compressor due to an excessive operating capacity without using a variable displacement compressor. It is an object of the present invention to provide a highly reliable refrigeration cycle device that can prevent such a situation.

[0007]

In order to achieve the above object, the present invention relates to a plurality of constant capacity compressors connected in parallel, a heat source side heat exchanger, a first expansion device, and a use side. A refrigeration cycle apparatus including a refrigerant circuit formed by connecting heat exchangers by pipes and configured to control the number of operating compressors according to a load on a use side, wherein a heat source side heat exchanger and a first expansion device And a bypass provided by connecting a first branch provided in the refrigerant circuit between the first heat exchanger and the second branch provided in the refrigerant circuit between the use-side heat exchanger and the compressor. An auxiliary heat exchanger provided in the bypass path, and a second expansion device provided in the bypass path between the first branch portion and the auxiliary heat exchanger. If the total operating capacity of the The is so diverted to bypass those configured to evaporate or condensed in the auxiliary heat exchanger.

Further, in the above configuration, the auxiliary heat exchanger exchanges heat between the refrigerant in the bypass and the air in the heat source side air passage.

In the above structure, the auxiliary heat exchanger performs heat exchange between the refrigerant in the bypass and the high-temperature and high-pressure refrigerant discharged from the compressor.

In the above structure, the refrigerant circuit between the heat source side heat exchanger and the first expansion device and the bypass between the second expansion device and the auxiliary heat exchanger are connected to each other. A second connection pipe that connects the first connection pipe, the bypass path between the auxiliary heat exchanger and the second branch, and the refrigerant circuit between the compressor and the heat source side heat exchanger. It comprises a connection pipe and an opening / closing means for opening and closing the first connection pipe and the second connection pipe.

Further, in the above configuration, the second throttle device is a flow control valve capable of controlling the opening degree.

Further, in the above structure, heat exchange is performed between the refrigerant in the bypass from the flow control valve to the auxiliary heat exchanger and the refrigerant in the refrigerant circuit from the heat source side heat exchanger to the first branch. It is equipped with a supercooling heat exchanger to perform.

Further, in the above construction, the suction pressure detecting means for detecting the suction pressure of the compressor, the detected value of the discharge pressure detecting means for detecting the discharge pressure of the compressor, the heat source side heat exchanger, and the first throttle device Supercooling degree calculating means for calculating the degree of supercooling of the refrigerant based on the detected value of the first temperature detecting means for detecting the refrigerant temperature between the refrigerant and the refrigerant outlet side and the refrigerant inlet side of the auxiliary heat exchanger. Superheat degree calculating means for calculating the degree of superheat of the refrigerant based on the detected value of the second temperature detecting means for detecting each refrigerant temperature, and a predetermined value in which the detected value of the suction pressure detecting means is set in advance during the cooling operation In the following cases, the flow control valve is opened, and when the detected value of the suction pressure detecting means exceeds a predetermined value, the calculated value of the supercooling degree calculating means and the calculated value of the superheat degree calculating means are respectively set in advance. Close to the cooling target and superheat target A flow control valve is obtained and a first control means for opening control moves easily.

In the above construction, a discharge pressure detecting means for detecting a discharge pressure of the compressor, and a third temperature detecting means for detecting a detected value of the discharge pressure detecting means and a refrigerant temperature at a refrigerant outlet side of the auxiliary heat exchanger. Means for calculating the degree of supercooling of the refrigerant based on the detected value of the means, and means for calculating the degree of supercooling of the refrigerant, and auxiliary heating when the detected value of the discharge pressure detecting means during heating operation is equal to or higher than a predetermined value. The opening degree of the flow control valve is controlled so that the calculated value of the exchanger supercooling degree calculating means approaches the preset supercooling degree target value, and if the detected value of the discharge pressure detecting means is less than the predetermined value, the flow rate is controlled. Second control means for performing control to close the control valve.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a refrigerant circuit diagram of an air-conditioning apparatus (refrigeration cycle apparatus) according to Embodiment 1 of the present invention, in which A and B are constant capacity compressors connected in parallel,
2 is a four-way switching valve, 3 is a heat source side heat exchanger, 4 is a flow control valve (first throttling device), 5 is a utilization side heat exchanger, and 8 is an accumulator. Thus, a refrigerant circuit 1 is formed. A compressor having a larger operating capacity than the compressor A is used as the compressor B.

C is a first branch provided in the refrigerant circuit 1 between the heat source side heat exchanger 3 and the flow control valve 4, and D is a connection between the use side heat exchanger 5 and the four-way switching valve 2. The second branch portion E provided in the refrigerant circuit 1 between the first branch portion C and the second branch portion D is provided by connecting the first branch portion C and the second branch portion D, and the second branch portion 10 is provided in the bypass passage E. The auxiliary heat exchanger 9 is a flow control valve (second throttle device) provided in the bypass E between the first branch C and the auxiliary heat exchanger 10. The auxiliary heat exchanger 10 is provided in the same heat source side air path as the heat source side heat exchanger 3 and exchanges heat between the refrigerant in the bypass path E and the air (outside air) in the heat source side air path. It is formed of a material having sufficient pressure resistance, and has a heat exchange capacity that can suppress a decrease in suction pressure and an excessive rise in discharge pressure due to an excessive compressor capacity with respect to a use-side load.

F connects the refrigerant circuit 1 between the first branch C and the flow control valve 4 and the refrigerant circuit 1 between the use side heat exchanger 5 and the second branch D. A supercooling pipe provided at 6; a flow control valve 6 provided at the supercooling pipe F;
Reference numeral 7 denotes a supercooling heat exchanger that performs heat exchange between the refrigerant in the supercooling pipe F and the refrigerant in the refrigerant circuit 1.

Next, the operation will be described. In a normal cooling operation, the four-way switching valve 2 is switched to a direction in which the discharge sides of the compressors A and B and the heat source side heat exchanger 3 communicate with each other, and the flow control valve 9 is fully closed to open the compressors A and B. Operate either or both. The high-temperature and high-pressure gas refrigerant discharged from the compressors A and B flows into the heat source side heat exchanger 3 via the four-way switching valve 2, where it exchanges heat with the outside air to become a high-temperature and high-pressure gas-liquid two-phase refrigerant. . The gas-liquid two-phase refrigerant that has exited the heat source side heat exchanger 3 is supercooled by the supercooling heat exchanger 7 and flows into the use side.
After the pressure is reduced by the flow control valve 4, it flows into the use side heat exchanger 5, where it exchanges heat with indoor air to become a low-temperature low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant leaving the use side heat exchanger 5 is:
The gas refrigerant flows into the accumulator 8 via the four-way switching valve 2 and is separated into gas and liquid. The liquid refrigerant is stored in the accumulator 8 and the gas refrigerant returns to the compressors A and B. A refrigeration cycle is formed as described above. A part of the refrigerant flowing out of the subcooling heat exchanger 7 is diverted to the supercooling pipe F, and is decompressed by the flow control valve 6 to become a low-temperature low-pressure gas-liquid two-phase refrigerant, and becomes a subcooling heat exchanger 7.
Flows again and exchanges heat with the refrigerant in the refrigerant circuit 1 to supercool, and then joins the refrigerant circuit 1 between the use side heat exchanger 5 and the second branch portion D.

When the operating capacity of the compressor becomes excessive with respect to the air conditioning load on the user side, and the evaporation pressure in the system, that is, the suction pressure of the compressors A and B decreases, the bypass passage E
Is opened. Thereby, the heat source side heat exchanger 3
A part of the gas-liquid two-phase refrigerant that has flowed out is divided into the bypass passage E at the first branch portion C, and after being reduced in pressure by the flow control valve 9, flows into the auxiliary heat exchanger 10, where heat exchange with outside air is performed. After that, the refrigerant merges with the refrigerant in the refrigerant circuit 1 at the second branch portion D.
As described above, since the refrigerant evaporated in the auxiliary heat exchanger 10 flows into the suction sides of the compressors A and B, the suction pressures of the compressors A and B increase, and the compressors A and B are forced to operate. A heavy load is prevented.

In a normal heating operation, the four-way switching valve 2
Is switched to a direction in which the discharge side of the compressors A and B communicates with the use side heat exchanger 5, and the flow control valves 6 and 9 are fully closed to operate one or both of the compressors A and B. .
The high-temperature and high-pressure gas refrigerant discharged from the compressors A and B flows into the use-side heat exchanger 5 through the four-way switching valve 2, where it exchanges heat with indoor air to form a high-temperature and high-pressure liquid single-phase refrigerant. Become. The liquid single-phase refrigerant that has exited the use-side heat exchanger 5 is decompressed by the use-side flow control valve 4, passes through the subcooling heat exchanger 7, flows into the heat-source-side heat exchanger 3, where the outside air and heat It is replaced with a low-temperature, low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant that has exited the heat source side heat exchanger 3 flows into the accumulator 8 via the four-way switching valve 2 and is separated into gas and liquid. The liquid refrigerant is stored in the accumulator 8, and the gas refrigerant is compressed by the compressors A and Return to B. A refrigeration cycle is formed as described above.

When the operating capacity of the compressor becomes excessive with respect to the air conditioning load on the user side, and the condensing pressure in the system, that is, the discharge pressure of the compressors A and B rises excessively, the bypass passage E
Is opened. As a result, a part of the high-temperature and high-pressure gas single-phase refrigerant discharged from the compressors A and B is diverted to the bypass path E at the second branch portion D, exchanges heat with the outside air in the auxiliary heat exchanger 10, and condenses. After that, the refrigerant merges with the refrigerant in the refrigerant circuit 1 at the first branch portion C. As described above, a part of the gas refrigerant on the discharge side of the compressors A and B is condensed in the auxiliary heat exchanger 10, so that the discharge pressures of the compressors A and B decrease. An unreasonable load is prevented from being applied to B.

FIG. 2 shows the relationship between the use side load and the total operating capacity of the compressors A and B in this embodiment. As described above, when the use side load is minimum, only the compressor A is operated, when the use side load is increased to some extent, only the compressor B is operated, and when the use side load is further increased, the compressor A and the compressor B are connected. When the number of operating units is controlled to operate both, the utilization side load changes steplessly, while the total operating capacity of the compressor changes stepwise. In the indicated area, the total operating capacity of the compressor was excessive with respect to the use side load. On the other hand, in this embodiment, a part of the refrigerant is
And is evaporated or condensed in the auxiliary heat exchanger 10 in the same manner as in the use side heat exchanger 5, so that the use side load increases, and the auxiliary heat exchanger 10 Will be absorbed. Therefore, substantially the same effect as in the case where the operating capacity of the compressor is linearly controlled can be obtained, and no adverse effect is caused by the inverter.

Embodiment 2 FIG. 3 and 4 are refrigerant circuit diagrams of an air conditioner (refrigeration cycle device) according to Embodiment 2 of the present invention. In the drawings, components that are the same as or correspond to those of the above-described embodiment have the same reference numerals. And the description is omitted. 11 is a heat source side heat exchanger 3 and a flow control valve 4
The first refrigerant circuit 1 is connected to a refrigerant circuit 1 (a first expansion device) and a bypass path E between a flow control valve 9 (a second expansion device) and an auxiliary heat exchanger 10. Connection piping. Reference numeral 12 denotes the auxiliary heat exchanger 10 and the second branch portion D
And a refrigerant circuit 1 between the compressors A and B and the heat-source-side heat exchanger 3. Further, 13 is an on-off valve (opening / closing means) provided on the first connection pipe 11, 14 is an on-off valve (opening / closing means) provided on the second connection pipe 12, and 15 is a connection of the second connection pipe 12. This is an on-off valve provided in a bypass E between the position and the second branch portion D.

Next, the operation will be described. In a normal cooling operation, the four-way switching valve 2 is switched to a direction in which the discharge sides of the compressors A and B and the heat source side heat exchanger 3 are communicated with each other.
3 is opened, and the on-off valve 15 is closed to operate one or both of the compressors A and B. The high-temperature and high-pressure gas refrigerant discharged from the compressors A and B passes through the four-way switching valve 2 as shown by the solid arrow in FIG. Flows into the heat source side heat exchanger 3.

The gas refrigerant flowing into the heat source side heat exchanger 3 is
Here, it exchanges heat with the outside air to become a high-temperature and high-pressure gas-liquid two-phase refrigerant. Further, the gas refrigerant diverted to the second connection pipe 12 flows into the auxiliary heat exchanger 10 in the bypass E, where it exchanges heat with the outside air to become a high-temperature and high-pressure gas-liquid two-phase refrigerant,
Through the connection pipe 11 of FIG. 2 and the gas-liquid two-phase refrigerant from the heat source side heat exchanger 3. Then, it is supercooled by the supercooling heat exchanger 7 and flows into the use side, and after being depressurized by the flow control valve 4, flows into the use side heat exchanger 5 where it exchanges heat with indoor air. It becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant that has exited from the use side heat exchanger 5 flows into the accumulator 8 via the four-way switching valve 2 and is separated into gas and liquid. The liquid refrigerant is stored in the accumulator 8 and the gas refrigerant is compressed by the compressors A and Return to B. A refrigeration cycle is formed as described above. Further, a part of the refrigerant that has exited the supercooling heat exchanger 7 is diverted to the supercooling pipe F, and is decompressed by the flow control valve 6 to be a low-temperature low-pressure gas-liquid two-phase refrigerant, which is transmitted to the supercooling heat exchanger 7. After flowing again, the refrigerant in the refrigerant circuit 1 exchanges heat with the refrigerant in the refrigerant circuit 1 to perform supercooling, and then joins the refrigerant circuit 1 between the use side heat exchanger 5 and the second branch portion D.

Then, when the compressor capacity becomes excessive with respect to the utilization side load and the suction pressure of the compressors A and B decreases, the on-off valves 12 and 13 are closed and the on-off valve 15 is closed. As a result, as shown by the dotted arrow in FIG. 3, a part of the gas-liquid two-phase refrigerant that has exited the heat source side heat exchanger 3 is diverted to the bypass E at the first branch C, and the flow control valve 9 After flowing into the auxiliary heat exchanger 10 and absorbing heat from the outside air and partially evaporating, the refrigerant circuit 1
Merges with the refrigerant inside. As described above, since the suction pressures of the compressors A and B increase, it is prevented that excessive loads are applied to the compressors A and B due to excessive operating capacity.

In a normal heating operation, the four-way switching valve 2
In the direction in which the discharge sides of the compressors A and B and the use side heat exchanger 5 are communicated, and the on-off valves 12 and 13 are opened.
The on-off valve 15 is closed to operate one or both of the compressors A and B. The high-temperature and high-pressure gas refrigerant discharged from the compressors A and B flows into the use side heat exchanger 5 through the four-way switching valve 2 as shown by the solid line arrows in FIG. It is replaced with a high-temperature, high-pressure liquid single-phase refrigerant. The liquid single-phase refrigerant that has exited from the use-side heat exchanger 5 is decompressed by the use-side flow control valve 4, passes through the supercooling heat exchanger 7, and then partially passes through the first
And the other flows into the heat source side heat exchanger 3. The liquid single-phase refrigerant that has flowed into the heat-source-side heat exchanger 3 exchanges heat with the outside air to become a low-temperature and high-pressure gas-liquid two-phase refrigerant. The liquid single-phase refrigerant that has flowed into the first connection pipe 11 flows into the auxiliary heat exchanger 10 in the bypass passage E, where it exchanges heat with the outside air to become a low-temperature and high-pressure gas-liquid two-phase refrigerant. Through the connection pipe 12 of FIG. 1 and joins the gas-liquid two-phase refrigerant from the heat source side heat exchanger 3. Then, the gas refrigerant flows into the accumulator 8 via the four-way switching valve 2 and is separated into gas and liquid. The liquid refrigerant is stored in the accumulator 8 and the gas refrigerant returns to the compressors A and B. A refrigeration cycle is formed as described above.

When the operating capacity of the compressor becomes excessive with respect to the air conditioning load on the user side and the discharge pressure of the compressors A and B rises excessively, the on-off valves 12 and 13 are closed,
The on-off valve 15 is closed. Thereby, as indicated by the dotted arrows in FIG. 4, a part of the high-temperature and high-pressure gas refrigerant discharged from the compressors A and B is diverted to the bypass passage E side at the second branch portion D, and the auxiliary heat exchange is performed. After exchanging heat with the outside air in the heat exchanger 10, it becomes a high-pressure, high-temperature liquid single-phase refrigerant, and then decompressed by the flow control valve 9 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant. With the refrigerant. As described above, the compressors A and B
Of the compressors A and B due to a decrease in the discharge pressure of the compressors A and B due to excessive operating capacity is prevented.

As described above, in this embodiment, in both the cooling operation and the heating operation, if the operating capacity of the compressor is not excessive, the auxiliary heat exchanger 10 is connected to the heat source side heat exchanger. Can be used for the same purpose as 3. Therefore, since the heat exchange capacity required for normal operation only needs to be ensured by both the heat source side heat exchanger 3 and the auxiliary heat exchanger 10, the auxiliary heat exchanger 10 is replaced by an excessive operating capacity of the compressor. The heat exchange capacity of the heat source side heat exchanger 3 can be reduced as compared with the case where the heat exchanger 3 is used only for absorbing.

Embodiment 3 FIG. 5 is a refrigerant circuit diagram of an air conditioner (refrigeration cycle device) according to Embodiment 3 of the present invention. In the figure, A and B are fixed capacity compressors connected in parallel, 2 is a four-way switching valve, 3 is a heat source side heat exchanger, 4 is a flow control valve (first throttle device), and 5 is used. The side heat exchanger 8 is an accumulator, and the above components are connected by piping to form the refrigerant circuit 1. F is a circuit provided by connecting the refrigerant circuit 1 between the heat source side heat exchanger 3 and the flow control valve 4 and the refrigerant circuit 1 between the use side heat exchanger 5 and the four-way switching valve 2. A cooling pipe, 6 is a flow control valve provided in the supercooling pipe F, and 7 is a supercooling heat exchanger that exchanges heat between the refrigerant in the supercooling pipe F and the refrigerant in the refrigerant circuit 1. is there.

A branch 16 branches from the refrigerant circuit 1 between the heat source side heat exchanger 3 and the subcooling heat exchanger 7 and a capillary tube 17 (second expansion device) and the auxiliary heat exchanger 1 on the way.
0 is provided and a refrigerant pipe provided with a flow path control valve 18 (opening / closing means) at the end, and 19 is provided by connecting the refrigerant circuit 1 between the four-way switching valve 2 and the accumulator 8 and the flow path switching valve 18. Refrigerant pipe 20, compressors A and B and four-way switching valve 2
Is a refrigerant pipe provided by connecting the refrigerant circuit 1 and the flow path switching valve 18 between the refrigerant pipe 1 and the flow path switching valve 18.
It is configured to be switchable so that either one of 9 and 20 communicates with the refrigerant pipe 16. In addition, the auxiliary heat exchanger 1
Numeral 0 is provided in a heat source side air passage common to the heat source side heat exchanger 3. Further, a reference numeral 11 is provided to connect the refrigerant circuit 1 between the heat source side heat exchanger 3 and the subcooling heat exchanger 7 and the refrigerant pipe 16 between the capillary tube 17 and the auxiliary heat exchanger 10. Reference numeral 1 denotes a connection pipe, and reference numeral 13 denotes an opening / closing valve (opening / closing means) provided in the first connection pipe 11.

Next, the operation will be described. In a normal cooling operation, the four-way switching valve 2 is connected to the compressors A and B and the heat source side heat exchanger 3.
And the flow path switching valve 18 is switched to a direction in which the refrigerant pipe 16 and the refrigerant pipe 20 communicate with each other, and the on-off valve 13 is opened to operate one or both of the compressors A and B. I do. Part of the high-temperature and high-pressure gas refrigerant discharged from the compressors A and B is diverted to the refrigerant pipe 20 and flows into the auxiliary heat exchanger 10 of the refrigerant pipe 16 via the flow path switching valve 18. On the other hand, the gas refrigerant that has not flowed to the refrigerant pipe 20 flows into the heat source side heat exchanger 3 via the four-way switching valve 2.
The gas refrigerant that has flowed into the heat source side heat exchanger 3 and the auxiliary heat exchanger 10 exchanges heat with the outside air to become a high-temperature, high-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant from the auxiliary heat exchanger 10 enters the first connection pipe 11 from the refrigerant pipe 16,
It merges with the gas-liquid two-phase refrigerant from the heat source side heat exchanger 3 flowing in the refrigerant pipe 1. Then, it is supercooled by the supercooling heat exchanger 7 and flows into the use side. After being depressurized by the flow control valve 4, it flows into the use side heat exchanger 5, where it exchanges heat with indoor air to reduce the temperature. It becomes a low-pressure gas-liquid two-phase refrigerant. User side heat exchanger 5
Is discharged into the accumulator 8 via the four-way switching valve 2 and separated into gas and liquid. The liquid refrigerant is stored in the accumulator 8 and only the gas refrigerant is sucked into the compressors A and B. A refrigeration cycle is formed as described above. A part of the refrigerant flowing out of the subcooling heat exchanger 7 is diverted to the subcooling circuit F, and is decompressed by the flow control valve 6 to become a low-temperature low-pressure gas-liquid two-phase refrigerant, which is transferred to the subcooling heat exchanger 7 After flowing again, it exchanges heat with the high-temperature and high-pressure gas-liquid two-phase refrigerant in the refrigerant circuit 1 to supercool the gas-liquid two-phase refrigerant, and then connects the use-side heat exchanger 5 and the four-way switching valve 2 to each other. Merges into the intervening refrigerant circuit 1.

When the compressor capacity becomes excessive with respect to the use side load and the evaporation pressure (suction pressure of the compressor) in the system decreases, the flow path switching valve 18 is connected to the refrigerant pipe 16 and the refrigerant pipe 19. Are switched to communicate with each other, and the on-off valve 13 is closed. As a result, as shown by solid arrows in FIG. 5, a part of the high-temperature and high-pressure liquid single-phase refrigerant that has exited the heat source side heat exchanger 3 is diverted to the refrigerant pipe 16 and the capillary tube 17
After flowing into the auxiliary heat exchanger 10, it exchanges heat with the outside air to increase the evaporation pressure in the system, and then from the refrigerant pipe 16 through the flow path switching valve 18 and the refrigerant pipe 19,
The refrigerant merges with the refrigerant from the use side heat exchanger 5 flowing in the refrigerant circuit 1 and flows into the accumulator 8. As described above, since the suction pressures of the compressors A and B increase, it is prevented that excessive loads are applied to the compressors A and B due to excessive operating capacity.

In this embodiment, during cooling operation, a series of pipes composed of the refrigerant pipe 16 and the refrigerant pipe 19 serve as a bypass in the present invention, and the refrigerant pipe 20 serves as a second connection pipe in the present invention. Becomes

In a normal heating operation, the four-way switching valve 2
In the direction in which the discharge side of the compressors A and B and the use side heat exchanger 5 communicate with each other, and the flow path switching valve 18 in the direction in which the refrigerant pipe 16 and the refrigerant pipe 19 communicate with each other. Open to operate one or both of compressors A and B. The high-temperature and high-pressure gas refrigerant discharged from the compressors A and B flows into the use-side heat exchanger 5 through the four-way switching valve 2, where it exchanges heat with indoor air to form a high-temperature and high-pressure liquid single-phase refrigerant. Become. The liquid single-phase refrigerant that has exited the use-side heat exchanger 5 is depressurized by the flow control valve 4, passes through the supercooling heat exchanger 7, and is partially diverted to the first connection pipe 11.
Flows into the auxiliary heat exchanger 10. On the other hand, the refrigerant not divided into the connection pipe 11 flows into the heat source side heat exchanger 3. The refrigerant that has flowed into the heat source side heat exchanger 3 and the auxiliary heat exchanger 10 exchanges heat with the outside air to become a low-temperature low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant that has exited the auxiliary heat exchanger 10 passes through the refrigerant pipe 16 through the flow path switching valve 18 and the refrigerant pipe 19, and flows into the refrigerant circuit 1 from the heat source-side heat exchanger 3 that flows through the refrigerant circuit 1. Join. Then, the combined gas-liquid two-phase refrigerant flows into the accumulator 8 and is separated into gas and liquid. The liquid refrigerant is stored in the accumulator 8, and only the gas refrigerant is supplied to the compressors A and B.
Inhaled. A refrigeration cycle is formed as described above.

When the compressor capacity becomes excessive with respect to the use side load and the condensing pressure (discharge pressure of the compressor) in the system rises excessively, the flow path switching valve 18 is connected to the refrigerant pipe 16 and the refrigerant pipe 20. And the on-off valve 13 is closed. Thereby, as indicated by the dotted arrows in FIG. 5, a part of the high-temperature and high-pressure gas refrigerant discharged from the compressors A and B is diverted to the refrigerant pipe 20 and passes through the flow path switching valve 18 to the refrigerant pipe 16. The refrigerant flows into the auxiliary heat exchanger 10, where it exchanges heat with the outside air to become a high-pressure and high-temperature liquid single-phase refrigerant, thereby reducing the condensation pressure in the system. Then, after being decompressed by the capillary tube 17 to be in a low-temperature and low-pressure gas-liquid two-phase state, the refrigerant flows into the heat source side heat exchanger 3 by merging with the refrigerant flowing from the utilization side flowing in the refrigerant circuit 1. As described above, since the discharge pressures of the compressors A and B decrease, it is prevented that excessive loads are applied to the compressors A and B due to excessive operating capacity.

In this embodiment, during the heating operation, a series of pipes composed of the refrigerant pipe 16 and the refrigerant pipe 20 constitute the bypass passage according to the present invention, and the refrigerant pipe 19 serves as the second connection pipe according to the present invention. Becomes

FIG. 6 is a refrigerant circuit diagram of another air conditioner (refrigeration cycle device) according to the third embodiment. This refrigerant circuit is provided with the exception that an on-off valve 21 (opening / closing means) is provided on the refrigerant pipe 19 and an on-off valve 22 (opening / closing means) is provided on the refrigerant pipe 20 instead of providing the flow path switching valve 18. Has the same circuit configuration as the refrigerant circuit of FIG.

Therefore, the normal cooling operation is performed with the on-off valve 1
3 and the on-off valve 22 are opened, and the on-off valve 21 is closed. Also,
When the compressor capacity becomes excessive with respect to the use side load during the cooling operation and the suction pressure of the compressor decreases, the on-off valve 21 is opened, and the on-off valves 13 and 20 are closed.
As in the case of FIG. 5, a part of the high-temperature and high-pressure liquid single-phase refrigerant that has exited the heat source side heat exchanger 3 is diverted to the refrigerant pipe 16 and passes through the capillary tube 17 to become a low-temperature and low-pressure gas-liquid two-phase. After that, it flows into the auxiliary heat exchanger 10, where it exchanges heat with the outside air to raise the evaporation pressure in the system, and joins the refrigerant circuit 1 via the refrigerant pipe 19.

In a normal heating operation, the on-off valve 13 and the on-off valve 21 are opened, and the on-off valve 22 is closed.
Is performed with the same refrigerant flow as in the case of (1). Then, when the compressor capacity becomes excessive with respect to the use side load during the heating operation and the discharge pressure of the compressor rises excessively, the on-off valve 22 is opened, and the on-off valves 13 and 21 are closed. As in the case of the above, part of the high-temperature and high-pressure gas refrigerant discharged from the compressors A and B flows into the refrigerant pipe 16 via the refrigerant pipe 20, and exchanges heat with the outside air in the auxiliary heat exchanger 10 to make the system The condensing pressure is reduced to become a high-temperature and high-pressure liquid single-phase refrigerant, which is then decompressed by the capillary tube 17 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant, and then joins the refrigerant circuit 1.

Embodiment 4 FIG. FIG. 7 is a refrigerant circuit diagram of an air conditioner (refrigeration cycle device) according to Embodiment 4 of the present invention. This refrigerant circuit has the same circuit configuration as the refrigerant circuit of FIG. 5 except that a flow control valve 23 whose opening degree can be controlled is provided instead of the capillary tube 17 as a second expansion device. .

Therefore, in a normal cooling operation, the flow control valve 23 is fully closed and the on-off valve 13 is opened to
Is performed with the same refrigerant flow as in the case of (1). When the compressor capacity becomes excessive with respect to the use-side load during the cooling operation and the suction pressure of the compressor decreases, the flow path switching valve 18 is switched to a direction in which the refrigerant pipe 16 and the refrigerant pipe 19 communicate with each other. After closing the on-off valve 13, the opening of the flow control valve 23 is adjusted so that the suction pressure of the compressor converges to a predetermined value.

In the normal heating operation, the flow control valve 23
Is fully closed, and the on-off valve 13 is opened to perform the same refrigerant flow as in FIG. If the compressor capacity becomes excessive with respect to the use side load during the heating operation and the discharge pressure of the compressor rises excessively, the flow path switching valve 18 is connected to the refrigerant pipe 1.
After switching to a direction in which the refrigerant pipe 6 communicates with the refrigerant pipe 20 and closing the on-off valve 13, the opening of the flow control valve 23 is adjusted so that the discharge pressure of the compressor converges to a predetermined value.

Since the above-described control is performed, the suction pressure and the discharge pressure of the compressor can be controlled with higher accuracy than when the capillary tube 17 is provided in the refrigerant pipe 16 as shown in FIG. Thus, a more reliable refrigeration cycle device can be obtained.

FIG. 8 is a refrigerant circuit diagram of another air conditioner (refrigeration cycle device) according to the fourth embodiment. This refrigerant circuit has the same circuit configuration as the refrigerant circuit of FIG. 6 except that a flow control valve 23 whose opening degree can be controlled is provided instead of the capillary tube 17 as a second expansion device. . Therefore, the way of opening and closing the on-off valves 13, 21, and 22 is the same as that of the refrigerant circuit of FIG. 6, and the degree of opening control of the flow control valve 23 is the same as that of the refrigerant circuit of FIG.

Embodiment 5 FIG. FIG. 9 is a refrigerant circuit diagram of an air conditioner (refrigeration cycle device) according to Embodiment 5 of the present invention. In the drawing, A and B are parallel-connected constant displacement compressors, and 2 is a four-way compressor. Switching valve, 3 is heat source side heat exchanger, 4
Is a flow control valve (first throttle device), 5 is a use side heat exchanger, 8 is an accumulator, and the above components are connected by piping to form a refrigerant circuit 1. Also, C
Is a refrigerant circuit 1 between the heat source side heat exchanger 3 and the flow control valve 4
Is a second branch provided in the refrigerant circuit 1 between the use side heat exchanger 5 and the four-way switching valve 2, and E is a first branch C and the first branch. 2 is a bypass path connected to the branch section D, 10 is an auxiliary heat exchanger provided in the bypass path E, 9 is the first branch section C and the auxiliary heat exchanger 1
0 and a flow control valve (second
Aperture device). The auxiliary heat exchanger 10 is provided in the same heat source side air passage as the heat source side heat exchanger 3 and exchanges heat between the refrigerant in the bypass passage E and the air (outside air) in the heat source side air passage. is there. Further, 24 performs heat exchange between the refrigerant in the bypass E between the flow control valve 9 and the auxiliary heat exchanger 10 and the refrigerant from the heat source side heat exchanger 3 to the first branch C. Is a supercooling heat exchanger provided as described above.

Next, the operation will be described. In normal cooling operation, one or both of the compressors A and B are operated by switching the four-way switching valve 2 in a direction in which the discharge sides of the compressors A and B and the heat source side heat exchanger 3 communicate with each other. The high-temperature and high-pressure gas refrigerant discharged from the compressors A and B flows into the heat source side heat exchanger 3 via the four-way switching valve 2, and becomes a high-temperature and high-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant that has exited the heat source side heat exchanger 3 is supercooled by the supercooling heat exchanger 24, flows into the use side, is depressurized by the use side flow control valve 4, and is decompressed. The refrigerant flows into the heat exchanger 5 and becomes a low-temperature low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant that has exited from the use side heat exchanger 5 passes through the four-way switching valve 2 and is separated into gas and liquid by the accumulator 8. Flows into A refrigeration cycle is formed as described above. The high-temperature and high-pressure gas-liquid two-phase refrigerant from the heat source side heat exchanger 3 exits the supercooling heat exchanger 24, and a part of the refrigerant is diverted to the bypass path E. It becomes a low-pressure gas-liquid two-phase refrigerant and flows into the supercooling heat exchanger 24 again, where it exchanges heat with the high-temperature and high-pressure gas-liquid two-phase refrigerant in the refrigerant circuit 1 and passes through the refrigerant in the refrigerant circuit 1. Turn on cooling.
After passing through the auxiliary heat exchanger 10, the second branch portion D
To join the refrigerant circuit 1.

When the compressor capacity becomes excessive with respect to the utilization side load and the suction pressure of the compressor decreases, the opening of the flow control valve 9 is increased, as shown by a solid line arrow in FIG. The amount of the gas-liquid two-phase refrigerant flowing from the refrigerant circuit 1 to the bypass path E and flowing into the auxiliary heat exchanger 10 via the supercooling heat exchanger 24 increases. Therefore, the gas-liquid two-phase refrigerant exchanges heat with the outside air in the auxiliary heat exchanger 10 and evaporates, and then joins the refrigerant circuit 1, thereby increasing the suction pressure of the compressor.

In the cooling operation for heating, the four-way switching valve 2
Is switched to a direction in which the discharge side of the compressors A and B and the use side heat exchanger 5 communicate with each other, and one or both of the compressors A and B are operated. The high-temperature and high-pressure gas refrigerant discharged from the compressors A and B flows into the use-side heat exchanger 5 via the four-way switching valve 2, and becomes a high-temperature and high-pressure liquid single-phase refrigerant. The liquid single-phase refrigerant that has exited the use-side heat exchanger 5 is depressurized by the use-side flow control valve 4, passes through the subcooling heat exchanger 24, flows into the heat source-side heat exchanger 3, and has a low-temperature, low-pressure gas-liquid It becomes a two-phase refrigerant. Heat source side heat exchanger 3
Is discharged into the accumulator 8 via the four-way switching valve 2 and separated into gas and liquid. The liquid refrigerant is stored in the accumulator 8 and only the gas refrigerant is sucked into the compressors A and B. A refrigeration cycle is formed as described above.

When the compressor capacity becomes excessive with respect to the use side load and the discharge pressure of the compressor rises excessively, the flow control valve 9 is opened, and the high temperature and high pressure discharged from the compressors A and B are released. A part of the gas single-phase refrigerant is diverted to the bypass path E at the second branch portion D and flows into the auxiliary heat exchanger 10, where it exchanges heat with outside air to lower the discharge pressure of the compressor. At the first branch portion C, the refrigerant circuit 1 joins the refrigerant circuit 1.

As described above, the degree of opening of the flow control valve 9 is appropriately adjusted so that the refrigerant in the refrigerant circuit 1 is supercooled by the supercooling heat exchanger 24 during normal cooling operation. In addition, when the compressor capacity becomes excessive with respect to the utilization side load during the cooling operation and the heating operation, the excess amount is absorbed by the auxiliary heat exchanger 10 so that the suction pressure and the discharge pressure of the compressor can be precisely controlled. Can be controlled.

Further, when the supercooling pipe F is provided as in the refrigerant circuits of FIGS. 1 and 3 to 8, the supercooling pipe F
, A flow control valve 6 for the bypass passage E and a flow control valve 9 for the bypass path E are required, so that the number of flow control valves increases and the refrigeration cycle apparatus becomes expensive. In the refrigerant circuit, the number of flow control valves can be reduced while achieving substantially the same function as the refrigerant circuit, and the cost of the refrigeration cycle device can be reduced.

Embodiment 6 FIG. FIG. 10 is a refrigerant circuit diagram of an air conditioner (refrigeration cycle device) according to Embodiment 6 of the present invention. This refrigerant circuit is configured similarly to the refrigerant circuit of FIG. 9 except for the points described below. That is, the refrigerant circuit 1 between the compressors A and B and the four-way switching valve 2
Circuit 1 between the second branch portion D and the four-way switching valve 2
And a refrigerant pipe 25 provided to connect the The refrigerant pipe 25 is provided with an on-off valve 26 and a throttle device 27. Further, instead of the auxiliary heat exchanger 10 that exchanges heat with the outside air, an auxiliary heat exchanger 28 that exchanges heat between the refrigerant in the bypass E and the refrigerant in the refrigerant pipe 25 is provided.

Next, the operation will be described. When the compressor capacity becomes excessive with respect to the usage-side load during the cooling operation and the suction pressure of the compressor decreases, the on-off valve 26 is opened to open the compressor shown in FIG.
As indicated by a solid line arrow at 0, part of the high-temperature and high-pressure gas single-phase refrigerant discharged from the compressors A and B is diverted to the refrigerant pipe 25 and flows into the auxiliary heat exchanger. On the other hand, a part of the low-temperature and low-pressure gas-liquid two-phase refrigerant that has exited the supercooling heat exchanger 24 is diverted to the bypass passage E at the first branch C, passes through the subcooling heat exchanger 24 again, and It flows into the heat exchanger 28. Then, the refrigerant exchanges heat with the high-temperature and high-pressure gas single-phase refrigerant flowing into the auxiliary heat exchanger 28 from the refrigerant pipe 25 and evaporates to increase the suction pressure of the compressor.
To join. In addition, the refrigerant pipe 2 that has exited the auxiliary heat exchanger 28
The refrigerant in 5 passes through the on-off valve 26 and the expansion device 27 to join the refrigerant circuit 1. The auxiliary heat exchanger 28 has a heat exchange capacity capable of absorbing an excess of the compressor capacity with respect to the use-side load, and is, for example, a double tubular member formed of a material having a sufficient pressure resistance. A heat exchanger is used. The expansion device 27 is provided with a subcooling heat exchanger 24.
Is a flow path resistance for flowing an amount of gas refrigerant necessary for evaporating the low-temperature low-pressure gas-liquid two-phase refrigerant from the auxiliary heat exchanger 28 to the refrigerant pipe 25.

When the compressor capacity becomes excessive with respect to the utilization side load during the heating operation and the discharge pressure of the compressor rises excessively, when the flow control valve 9 of the bypass passage E is opened, FIG. As indicated by the dotted arrows, a part of the high-temperature and high-pressure gas single-phase refrigerant discharged from the compressors A and B and passing through the four-way switching valve 2 is transferred from the refrigerant circuit 1 to the bypass passage E at the second branch D. The sub flow is passed through the auxiliary heat exchanger 28,
Flows into Then, in the supercooling heat exchanger 28, heat exchange with the low-temperature low-pressure gas-liquid two-phase refrigerant from the flow control valve 4 on the utilization side flowing in the refrigerant circuit 1 is performed, and the refrigerant is condensed, thereby reducing the discharge pressure of the compressor. After that, the refrigerant circuit 1
To join.

Embodiment 7 FIG. FIG. 11 is a refrigerant circuit diagram of an air conditioner (refrigeration cycle device) according to Embodiment 6 of the present invention, and FIG. 12 is a control block diagram. In these figures, 41 is a suction pressure detecting means for detecting the suction pressure of the compressors A and B, 42 is a discharge pressure detecting means for detecting the discharge pressure of the compressors A and B, 43 is a heat source side heat exchanger 3 and The first temperature detecting means 44 for detecting the temperature of the refrigerant between the flow control valve 4 (first throttle device) and the detection value of the discharge pressure detecting means 42 and the detection value of the first temperature detecting means 43 A supercooling degree calculating means for calculating the degree of supercooling of the refrigerant based on the second temperature detecting means for detecting the respective refrigerant temperatures on the refrigerant outlet side and the refrigerant inlet side of the auxiliary heat exchanger; The superheat degree calculating means 40 calculates the degree of superheat of the refrigerant based on the detection value of the temperature detecting means 2 and the detection value of the suction pressure detecting means 41 and the respective calculations of the supercooling degree calculating means 44 and the superheat degree calculating means 46. The flow control valve 9 (second throttle device) based on the A first control means for degrees control. The configuration of the refrigerant circuit itself except for the above-described units is the same as that of FIG.

Next, based on the flowchart of FIG.
Next, the control operation of the first control means 40 will be described. S
In step S1, the detected value P of the suction pressure detecting means 41 is obtained._SIs the first
Predetermined suction pressure value P_SBIf it exceeds, go to step S2
move on. During the cooling operation, the compressors A and B
When the total operating capacity becomes excessive, the suction pressure is detected in step S1.
Detection value P of output means 41_SIs the first predetermined suction pressure value P_SBLess than
If it is, go to step S6. In step S2
Indicates that the calculated value SC of the subcooling degree calculating means 44 is
Value SC ₀If so, the process proceeds to step S3, where the calculated value SC
Is the supercooling degree target value SC₀If less, proceed to step S5
No.

[0058] In step S3, if the calculated value SH of the superheat degree calculation means 46 target superheat degree SH ₀ or proceeds to step S6, the process proceeds to step S4 if the calculated value SH is less than target superheat degree SH ₀ . In step S4, the detection value Pd of the discharge pressure detecting means 42 proceeds to step S6 if the predetermined discharge pressure value Pd ₀ or more, the detection value Pd proceeds to step S8 is less than the predetermined discharge pressure value Pd _0. In step S5, if the calculated value SH of the superheat degree calculation means 46 target superheat degree SH ₀ or proceeds to step S6, step S if the calculated value SH is less than target superheat degree SH ₀
Proceed to 8.

In step S6, control is performed to increase the opening of the flow control valve 9, and the process proceeds to step S7. In step S7, returns to step S1 If the detected value P _S of the intake pressure detecting means 41 is the second predetermined suction pressure value P _SU or higher,
If the detected value P _S is less than the second predetermined suction pressure value P _SU returns to step S6. In step S8, control is performed to reduce the opening of the flow control valve 9, and the process returns to step S1.

Accordingly, when the total operating capacity of the compressors A and B becomes excessive with respect to the utilization side load during the cooling operation and the suction pressure of the compressor drops, the flow control valve 9 is opened,
The amount of refrigerant diverted to the bypass E at the first branch C increases, and the suction pressure of the compressor is increased. Then, the flow control valve 9 is adjusted opening until it reaches the second predetermined suction pressure value P _SU the detected value P _S of the intake pressure detecting means 41 is separately set. When the suction pressure of the compressor has not decreased, the calculated value SC of the supercooling degree calculating means 44 and the calculated value SH of the superheating degree calculating means 46 are respectively set to the preset superheat degree target values SC ₀ and SC _0. flow control valve 9 is opening control so as to approach the target degree of superheat SH _0.

FIG. 14 shows the above control in FIG.
Suction pressure calculation means 4 when applied to refrigerant circuit 0
1, discharge pressure calculating means 42, first temperature detecting means 43,
And the arrangement of the second temperature detecting means (the first control means 40, the supercooling degree calculating means 44, and the superheating degree calculating means 46 are not shown). Thus, the refrigerant circuit using the auxiliary heat exchanger 28 for exchanging heat between the refrigerants also
It can be controlled similarly.

Embodiment 8 FIG. FIG. 15 is a refrigerant circuit diagram of an air conditioner (refrigeration cycle device) according to Embodiment 6 of the present invention, and FIG. 16 is a control block diagram. In these figures, reference numeral 42 denotes discharge pressure detecting means for detecting discharge pressures of the compressors A and B; 47, third temperature detecting means for detecting the refrigerant temperature on the refrigerant outlet side of the auxiliary heat exchanger 10; Auxiliary heat exchanger subcooling degree calculating means for calculating the degree of supercooling of the refrigerant based on the detected value of the pressure detecting means 42 and the detected value of the third temperature detecting means 47; This is second control means for controlling the opening of the flow control valve 9 (second throttle device) based on the operation value of the auxiliary heat exchanger subcooling degree operation means. The configuration of the refrigerant circuit itself except for the above-described units is the same as that of FIG.

Next, the control operation of the second control means 49 will be described with reference to the flowchart of FIG. Detection value Pd of the discharge pressure detecting means 42 in step S11 the flow control valve 9 proceeds to step S15 if less than the predetermined discharge pressure value Pd ₀ is fully closed, the flow returns to step S11. Compressor A to the usage-side load during heating operation, the total operating capacity of the B becomes excessive, if the detection value Pd of the discharge pressure detecting means 42 in step S11 is sufficient that above a predetermined discharge pressure value Pd ₀ Proceed to step S12. In step S12, control is performed to increase the opening of the flow control valve 9, and the process proceeds to step S13. In step S13, the calculated value SC is the subcooling degree target value SC ₀ of the auxiliary heat exchanger supercooling degree operating means 49
Returning to step S12 if the above calculated value SC proceeds to step S14 if it is less than the degree of subcooling target value SC _0.
In step S14, control is performed to reduce the opening of the flow control valve 9, and the process returns to step S11.

Accordingly, when the total operating capacity of the compressors A and B becomes excessive with respect to the utilization side load during the heating operation and the discharge pressure of the compressor rises excessively, the flow control valve 9 is opened,
The amount of refrigerant diverted to the bypass path E at the first branch portion C increases, and the discharge pressure of the compressor is reduced. Then, the flow control valve 9, the calculated value SC of the auxiliary heat exchanger supercooling degree operating means 49 is opening adjustment to approach the degree of supercooling target value SC _0. In addition, if the discharge pressure of the compressor is not excessively increased during the heating operation, the flow control valve 9 is fully closed, so that a decrease in the operating efficiency due to the branch flow of the refrigerant to the bypass E is prevented.

Although the air conditioner has been described above, the present invention can be applied to a refrigerating cycle device such as a refrigerator other than the air conditioner. Further, in the embodiment described above, two constant capacity compressors having different capacities are used. However, a refrigeration cycle apparatus using two constant capacity compressors having the same capacities, a different capacity or the like is used. The present invention is also applicable to a refrigeration cycle apparatus using three or more compressors having a capacity.

[0066]

As described above, in the refrigeration cycle apparatus according to the present invention, when the total operating capacity of the operated compressor becomes excessive with respect to the use side load, the refrigerant circuit is not operated. By diverting a part of the circulating refrigerant to the bypass path and evaporating or condensing it in the auxiliary heat exchanger, an excess of the compressor operating capacity can be absorbed in the auxiliary heat exchanger. Therefore, it is possible to avoid a situation in which an excessive load is applied to the compressor such that the suction pressure of the compressor decreases during the cooling operation or the discharge pressure of the compressor excessively increases during the heating operation, and high reliability can be avoided. A refrigeration cycle apparatus can be obtained, and various adverse effects due to the inverter do not occur as in the case where the operation capacity of the compressor is controlled using the inverter.

Further, if the auxiliary heat exchanger exchanges heat between the refrigerant in the bypass and the air in the heat source side air path, for example, a fan for blowing air may be connected to the auxiliary heat exchanger and the heat source side heat exchanger. The refrigeration cycle apparatus can be simplified because it can be shared with an exchanger.

If the auxiliary heat exchanger exchanges heat between the refrigerant in the bypass and the high-temperature and high-pressure refrigerant discharged from the compressor, the auxiliary heat exchanger is formed of, for example, a double tube. As a result, the size and cost of the refrigeration cycle device can be reduced.

In the case of the one provided with the first connection pipe, the second connection pipe, and the like, similarly to the refrigeration cycle apparatus, the total operating capacity of the operated compressor is excessive with respect to the use side load. When the operating capacity of the compressor is not excessive with respect to the air conditioning load on the user side, the refrigerant circulating through the refrigerant circuit Is supplied to the auxiliary heat exchanger through the first connection pipe and the second connection pipe, whereby the auxiliary heat exchanger can be used for the same purpose as the heat source side heat exchanger. Therefore, the heat exchange capacity required for normal operation can be secured by both the heat source side heat exchanger and the auxiliary heat exchanger,
Compared to the case where the auxiliary heat exchanger is used only for absorbing the excess operating capacity of the compressor, the heat source side heat exchanger can be downsized, and the refrigeration cycle device can be downsized and cost reduced. Can be achieved.

Further, when the second throttle device is a flow control valve capable of controlling the opening, the suction pressure or the discharge pressure of the compressor can be controlled with higher accuracy in accordance with the load on the user side. A more reliable refrigeration cycle device can be obtained.

Further, in the apparatus provided with a supercooling heat exchanger for exchanging heat between the refrigerant in the bypass passage and the refrigerant in the refrigerant circuit, a supercooling heat exchanger having a supercooling heat exchanger and a flow control valve is provided. The number of flow control valves can be reduced as compared with the case where a separate circuit is provided, so that the refrigeration cycle apparatus can be further simplified and the cost can be reduced.

Further, in the apparatus provided with the suction pressure detecting means, the supercooling degree calculating means, the superheating degree calculating means, the first control means, etc., the supercooling degree and the superheating degree of the refrigerant are brought close to the target values during the cooling operation. It can be operated in a suitable state, and the suction pressure of the compressor according to the air conditioning load on the user side, compared to the case where the opening control of the flow rate control valve in the bypass passage is performed based only on the suction pressure of the compressor. Can be controlled with higher accuracy, and a more reliable refrigeration cycle apparatus can be obtained.

Further, in the apparatus provided with the discharge pressure detecting means, the auxiliary heat exchanger subcooling degree calculating means, the second control means, and the like, the supercooling degree on the refrigerant outlet side of the auxiliary heat exchanger during the heating operation is set to the target. Value can be approached, and the discharge pressure of the compressor according to the air conditioning load on the user side is more accurate than in the case where the opening control of the flow control valve in the bypass path is performed based only on the discharge pressure of the compressor. , And a more reliable refrigeration cycle apparatus can be obtained.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram according to Embodiment 1 of the present invention.

FIG. 2 is a graph showing a relationship between a use side capacity and a total operating capacity of a compressor according to Embodiment 1 of the present invention.

FIG. 3 is a refrigerant circuit diagram according to Embodiment 2 of the present invention.

FIG. 4 is a refrigerant circuit diagram according to Embodiment 2 of the present invention.

FIG. 5 is a refrigerant circuit diagram according to Embodiment 3 of the present invention.

FIG. 6 is another refrigerant circuit diagram according to Embodiment 3 of the present invention.

FIG. 7 is a refrigerant circuit diagram according to Embodiment 4 of the present invention.

FIG. 8 is another refrigerant circuit diagram according to Embodiment 4 of the present invention.

FIG. 9 is a refrigerant circuit diagram according to Embodiment 5 of the present invention.

FIG. 10 is a refrigerant circuit diagram according to Embodiment 6 of the present invention.

FIG. 11 is a refrigerant circuit diagram according to Embodiment 7 of the present invention.

FIG. 12 is a control block diagram according to Embodiment 7 of the present invention.

FIG. 13 is a control flowchart according to Embodiment 7 of the present invention.

FIG. 14 is another refrigerant circuit diagram according to Embodiment 7 of the present invention.

FIG. 15 is a refrigerant circuit diagram according to Embodiment 8 of the present invention.

FIG. 16 is a control block diagram according to Embodiment 8 of the present invention.

FIG. 17 is a control flowchart according to Embodiment 8 of the present invention.

FIG. 18 is a graph showing the relationship between the usage-side capacity and the total operating capacity of the compressor in a conventional refrigeration cycle apparatus that controls the number of operating compressors.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 refrigerant circuit, 3 heat source side heat exchanger, 4 flow control valve (first throttle device), 5 utilization side heat exchanger, 9 flow control valve (second throttle device), 10 auxiliary heat exchanger, 11th 1 connection pipe, 12 second connection pipe, 13 on-off valve (opening / closing means), 14 on-off valve (opening / closing means), 16 refrigerant pipe, 17 capillary tube (second throttle device),
18 flow path switching valve (opening / closing means), 19 refrigerant pipe, 20
Refrigerant pipe, 21 on-off valve (opening / closing means), 22 on-off valve (opening / closing means), 23 flow control valve (second throttle device),
24 supercooling heat exchanger, 28 auxiliary heat exchanger, 40 first control means, 41 suction pressure detecting means, 42 discharge pressure detecting means, 43 first temperature detecting means, 44 supercooling degree calculating means, 45 second Temperature detecting means, 46 superheat degree calculating means, 47 third temperature detecting means, 48 auxiliary heat exchanger subcooling degree calculating means, 49 second control means, A compressor, B compressor, C first branch Section, D second branch, E bypass.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F25B 5/02 510 F25B 5/02 510J (72) Inventor Yoshihiro Sumida 2-3-2 Marunouchi, Chiyoda-ku, Tokyo, Mitsubishi Electric Corporation ( 72) Inventor Fumitake Unezaki 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (8)

[Claims] 1. A refrigerant circuit comprising a plurality of constant capacity compressors connected in parallel, a heat source side heat exchanger, a first expansion device, and a use side heat exchanger connected by piping, In a refrigeration cycle apparatus configured to control the number of operating compressors according to a use side load, a first refrigerant circuit provided in a refrigerant circuit between the heat source side heat exchanger and the first expansion device. And a bypass provided by connecting a second branch provided in a refrigerant circuit between the use side heat exchanger and the compressor, and an auxiliary heat provided in the bypass. An exchanger, and a second expansion device provided in a bypass between the first branch portion and the auxiliary heat exchanger. When the operating capacity becomes excessive with respect to the utilization side load, the refrigerant is supplied to the bypass passage. Refrigerating cycle apparatus characterized by being configured so as to divert evaporated or condensed in the auxiliary heat exchanger. 2. The refrigeration cycle apparatus according to claim 1, wherein the auxiliary heat exchanger exchanges heat between the refrigerant in the bypass passage and the air in the heat source side air passage. 3. The refrigeration cycle apparatus according to claim 1, wherein the auxiliary heat exchanger exchanges heat between the refrigerant in the bypass and the high-temperature and high-pressure refrigerant discharged from the compressor. 4. A first circuit provided by connecting a refrigerant circuit between the heat source side heat exchanger and the first expansion device and a bypass between the second expansion device and the auxiliary heat exchanger. A second connection pipe provided by connecting a connection pipe, a bypass path between the auxiliary heat exchanger and the second branch, and a refrigerant circuit between the compressor and the heat source side heat exchanger. The refrigeration cycle apparatus according to claim 2, further comprising: opening and closing means for opening and closing the first connection pipe and the second connection pipe. 5. The refrigeration cycle apparatus according to claim 1, wherein the second expansion device is a flow control valve whose opening degree can be controlled. 6. Supercooling heat for performing heat exchange between a refrigerant in a bypass from a flow control valve to an auxiliary heat exchanger and a refrigerant in a refrigerant circuit from a heat source side heat exchanger to a first branch. The refrigeration cycle apparatus according to claim 5, further comprising an exchanger. 7. A suction pressure detection means for detecting a suction pressure of a compressor, a detection value of a discharge pressure detection means for detecting a discharge pressure of the compressor, and a value between a heat source side heat exchanger and the first throttle device. Means for calculating the degree of supercooling of the refrigerant based on the detected value of the first temperature detecting means for detecting the temperature of the refrigerant, and the respective refrigerants on the refrigerant outlet side and the refrigerant inlet side of the auxiliary heat exchanger A superheat degree calculating means for calculating the degree of superheat of the refrigerant based on a detection value of the second temperature detecting means for detecting a temperature, and a detection value of the suction pressure detecting means during a cooling operation is equal to or less than a predetermined value. In this case, the flow control valve is opened, and when the detected value of the suction pressure detecting means exceeds the predetermined value, the calculated value of the supercooling degree calculating means and the calculated value of the superheat degree calculating means are respectively set in advance. Near the supercooling target and superheat target 7. A control device for controlling the opening of the flow control valve so as to be attached thereto.
A refrigeration cycle apparatus according to the paragraph. 8. A discharge pressure detecting means for detecting a discharge pressure of the compressor, and a third temperature detecting means for detecting a detected value of the discharge pressure detecting means and a refrigerant temperature at a refrigerant outlet side of the auxiliary heat exchanger. An auxiliary heat exchanger subcooling degree calculating means for calculating the degree of subcooling of the refrigerant based on the value, and the auxiliary heat exchange means when the detected value of the discharge pressure detecting means is not less than a predetermined value during a heating operation. The flow control valve is controlled so that the calculated value of the subcooling degree calculating means approaches a preset supercooling degree target value, and the detection value of the discharge pressure detecting means is less than the predetermined value. 7. The refrigeration cycle apparatus according to claim 5, further comprising: second control means for performing control for closing the flow control valve.