JP2007107820A - Air conditioner and air conditioner heat source unit used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain both reduction in cost and assurance of controllability, in an air conditioner with a refrigerant circuit capable of switching cooling and heating by changing the circulating direction of refrigerant, and an air conditioner heat source unit used therefor. <P>SOLUTION: The air conditioner 1 comprises the refrigerant circuit 10 in which a compressor 21 compressing the refrigerant, a heat source-side heat exchanger 23, a using-side heat exchanger 41, an expansion valve 24, and a four-way selector valve 22 are connected. The air conditioner 1 further comprises a pressure sensor 29 for high pressure and low pressure, which detects the pressure of the refrigerant carried between the four-way selector valve 22 and the using-side heat exchanger 41. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an air conditioner and a heat source unit of the air conditioner used therefor, in particular, an air conditioner including a refrigerant circuit that can be switched between heating and cooling by changing the circulation direction of the refrigerant, and a heat source of the air conditioner used therefor Regarding the unit.

Conventionally, there is an air conditioner including a refrigerant circuit that can be switched between heating and cooling by changing the circulation direction of the refrigerant. The refrigerant circuit of such an air conditioner is mainly configured by connecting a compressor, a four-way switching valve, a heat source side heat exchanger, an expansion valve, and a use side heat exchanger. .
In such an air conditioner, pressure values corresponding to the refrigerant evaporating pressure and the refrigerant condensing pressure are detected by providing pressure sensors in the compressor suction pipe and the compressor discharge pipe, respectively. (Refer to Patent Document 1 below).
JP 2001-349623 A

  In the air conditioner described above, the operation control of the air conditioner may be performed using the refrigerant evaporating pressure and the refrigerant condensing pressure corresponding to the refrigerant evaporating temperature and the refrigerant condensing temperature. The refrigerant evaporating pressure and the refrigerant condensing pressure can be obtained by a low pressure sensor provided in the suction pipe of the compressor and a high pressure sensor provided in the discharge pipe of the compressor. In other words, in the operation control of such an air conditioner, two pressure sensors are necessary. However, pressure sensors are expensive, and there is a need to reduce the number of pressure sensors as much as possible.

  Further, when a temperature sensor is provided at the liquid side end of the use side heat exchanger as in the above-described air conditioner, the temperature evaporating temperature of the refrigerant is obtained by this temperature sensor and the refrigerant condensing temperature is increased. It can also be obtained by a pressure sensor. However, when the refrigerant evaporating temperature and the refrigerant condensing temperature (or the refrigerant evaporating pressure and the refrigerant condensing pressure corresponding to the refrigerant evaporating temperature and the refrigerant condensing temperature) are used for operation control of the air conditioner, control is performed. From the standpoint of performance, it is often desirable to use a pressure sensor that responds quickly to changes in the operating state of the air conditioner rather than a temperature sensor.

  As described above, the conventional air conditioner is operated using the refrigerant evaporation temperature and the refrigerant condensation temperature (or the refrigerant evaporation pressure and the refrigerant condensation pressure corresponding to the refrigerant evaporation temperature and the refrigerant condensation temperature). When performing control, it is necessary to use two pressure sensors or a combination of a pressure sensor and a temperature sensor. As a result, it is difficult to achieve both cost reduction and ensuring controllability. It is.

  An object of the present invention is to achieve both cost reduction and ensuring controllability in an air conditioner having a refrigerant circuit that can be switched between heating and cooling by changing the circulation direction of the refrigerant and a heat source unit of the air conditioner used therefor. There is.

  An air conditioner according to a first aspect of the present invention includes a compressor that compresses a refrigerant, a heat source side heat exchanger, a use side heat exchanger, a liquid side end of the heat source side heat exchanger, and a liquid of the use side heat exchanger. A refrigerant circuit is provided in which an expansion mechanism connected between the side ends and a switching mechanism are connected. The switching mechanism is connected to the gas side end of the heat source side heat exchanger, the gas side end of the utilization side heat exchanger, the suction side end of the compressor, and the discharge side end of the compressor, and refrigerant discharged from the compressor Is switched in order of the heat source side heat exchanger, the expansion mechanism and the use side heat exchanger, and the refrigerant discharged from the compressor is circulated in the order of the use side heat exchanger, the expansion mechanism and the heat source side heat exchanger. It is possible to switch to the second switching state. And this air conditioning apparatus is provided with the pressure detection mechanism which detects the pressure of the refrigerant | coolant which flows between a switching mechanism and a utilization side heat exchanger.

Since this air conditioner includes a pressure detection mechanism that detects the pressure of the refrigerant flowing between the switching mechanism and the use side heat exchanger, when the switching mechanism is in the first switching state, the refrigerant evaporating temperature is set. The corresponding refrigerant pressure value can be detected, and when the switching mechanism is in the second switching state, the refrigerant pressure value corresponding to the refrigerant condensing temperature can be detected.
Thereby, the operation control of the air conditioner using the evaporation temperature of the refrigerant in the refrigeration cycle operation in the first switching state such as the cooling operation is performed only by one pressure detection mechanism, and the first operation such as the heating operation is performed. In the refrigeration cycle operation in the two-switching state, the operation control of the air conditioner using the refrigerant condensing temperature can be performed, so that both cost reduction and controllability can be achieved.

When the switching mechanism is in the first switching state in the air conditioning apparatus according to the first aspect of the present invention, the capacity of the compressor is based on the pressure value detected by the pressure detection mechanism. When the switching mechanism is in the second switching state, the compressor capacity is controlled based on the pressure value detected by the pressure detection mechanism.
In this air conditioner, the capacity control of the compressor in the refrigeration cycle operation in the first switching state such as the cooling operation can be performed based on the evaporation temperature of the refrigerant by only one pressure detection mechanism, and heating The capacity control of the compressor in the refrigeration cycle operation in the second switching state such as the operation can be performed based on the condensation temperature of the refrigerant.

An air conditioner according to a third aspect of the present invention is the air conditioner according to the second aspect, wherein when the switching mechanism is in the second switching state, the compressor discharges based on the pressure value detected by the pressure detection mechanism. Detects abnormal pressure.
In this air conditioner, the compressor discharge pressure abnormality can be detected in the refrigeration cycle operation in the second switching state such as the heating operation. Therefore, the compressor is protected by only one pressure detection mechanism. Can do.

An air conditioner according to a fourth invention is the air conditioner according to the second or third invention, wherein the refrigerant circuit includes a compressor, a heat source side heat exchanger, an expansion mechanism, and a switching mechanism, The utilization unit including the utilization side heat exchanger is configured by being connected via a liquid refrigerant communication pipe and a gas refrigerant communication pipe. The heat source unit includes a liquid side shut-off valve connected between the expansion mechanism connected to the liquid side end of the use side heat exchanger via the liquid refrigerant communication pipe and the liquid refrigerant communication pipe, and a gas refrigerant communication pipe. And a gas side closing valve connected between one end of the switching mechanism connected to the gas side end of the utilization side heat exchanger and the gas refrigerant communication pipe. In this air conditioner, the opening / closing abnormality of the closing valve is detected based on the pressure value detected by the pressure detection mechanism.
In this air conditioner, since the opening / closing abnormality of the closing valve can be detected, the compressor can be protected by only one pressure detection mechanism.

  An air conditioner according to a fifth aspect of the present invention is a heat source unit of an air conditioner connected to a utilization unit via a liquid refrigerant communication pipe and a gas refrigerant communication pipe, the compressor for compressing the refrigerant, and heat source side heat An exchanger, a liquid side closing valve connected to the liquid refrigerant communication pipe, a gas side closing valve connected to the gas refrigerant communication pipe, and a switching mechanism are provided. The switching mechanism is connected to the gas side end of the heat source side heat exchanger, the gas side closing valve, the suction side end of the compressor, and the discharge side end of the compressor, and the discharge side end of the compressor and the heat source side heat exchanger A first switching state in which the gas side end of the compressor is connected and the suction side end of the compressor is connected to the gas side shut-off valve, the discharge side end of the compressor is connected to the gas side shut-off valve, and the suction of the compressor is connected It can switch to the 2nd switching state which connects a side end and the gas side end of a heat-source side heat exchanger. And then. The heat source unit of the air conditioner includes a pressure detection mechanism that detects the pressure of the refrigerant flowing between the switching mechanism and the gas side shut-off valve.

  Since the heat source unit of this air conditioner has a pressure detection mechanism that detects the pressure of the refrigerant flowing between the switching mechanism and the gas-side shut-off valve, it is connected to the utilization unit via the refrigerant communication pipe. In the constructed air conditioner, when the switching mechanism is in the first switching state, the pressure value of the refrigerant corresponding to the evaporation temperature of the refrigerant can be detected, and when the switching mechanism is in the second switching state. The pressure value of the refrigerant corresponding to the condensation temperature of the refrigerant can be detected.

  As a result, in the air conditioner configured by being connected to the utilization unit via the refrigerant communication pipe, the refrigerant in the refrigeration cycle operation in the first switching state such as the cooling operation is performed by only one pressure detection mechanism. Operation control of the air conditioner using the evaporation temperature can be performed, and operation control of the air conditioner using the condensation temperature of the refrigerant can be performed in the refrigeration cycle operation in the second switching state such as the heating operation. Therefore, both cost reduction and ensuring controllability can be achieved.

As described above, according to the present invention, the following effects can be obtained.
In the first aspect of the invention, the operation control of the air conditioner using the evaporation temperature of the refrigerant is performed in the refrigeration cycle operation in the first switching state such as the cooling operation by only one pressure detection mechanism, and the heating operation is performed. In the refrigeration cycle operation in such a second switching state, the operation control of the air conditioner using the refrigerant condensing temperature can be performed, so that both cost reduction and securing of controllability can be achieved.

In the second invention, the capacity control of the compressor in the refrigeration cycle operation in the first switching state such as the cooling operation can be performed based on the evaporation temperature of the refrigerant by only one pressure detection mechanism, and the heating The capacity control of the compressor in the refrigeration cycle operation in the second switching state such as the operation can be performed based on the condensation temperature of the refrigerant.
In the third invention, the compressor can be protected by only one pressure detection mechanism.

In the fourth invention, the compressor can be protected by only one pressure detection mechanism.
In 5th invention, in the air conditioning apparatus comprised by connecting with a utilization unit via refrigerant | coolant communication piping, the refrigerating cycle operation in the 1st switching state like a cooling operation is only by one pressure detection mechanism. And controlling the operation of the air conditioner using the refrigerant condensing temperature in the refrigeration cycle operation in the second switching state such as the heating operation. Therefore, it is possible to achieve both cost reduction and ensuring controllability.

Embodiments of an air conditioner according to the present invention and a heat source unit used therefor will be described below with reference to the drawings.
(1) Overall Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 according to an embodiment of the present invention. The air conditioner 1 is an apparatus mainly used for indoor air conditioning by performing a vapor compression refrigeration cycle operation. The air conditioner 1 mainly includes a heat source unit 2, a utilization unit 4, a liquid refrigerant communication pipe 6 and a gas refrigerant communication pipe 7 that connect the heat source unit 2 and the utilization unit 4. That is, the vapor compression refrigerant circuit 10 of the air conditioner 1 of the present embodiment is configured by connecting the heat source unit 2, the utilization unit 4, the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7. ing.

(2) Configuration of Usage Unit The usage unit 4 is installed, for example, by embedding or hanging on a ceiling in a building, or hanging on a wall surface in a room. The utilization unit 4 is connected to the heat source unit 2 via the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7 and constitutes a part of the refrigerant circuit 10.

Next, the configuration of the usage unit 4 will be described. The usage unit 4 mainly includes a usage-side refrigerant circuit 10 a that constitutes a part of the refrigerant circuit 10. The use side refrigerant circuit 10 a mainly includes a use side heat exchanger 41.
In the present embodiment, the use side heat exchanger 41 is a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, and evaporates the refrigerant during cooling operation or dehumidifying operation. It is a heat exchanger that functions as a heat exchanger to cool indoor air and functions as a refrigerant condenser during heating operation to heat indoor air. The type of the use side heat exchanger 41 is not limited to the cross-fin type fin-and-tube type heat exchanger, and various types can be used.

In the present embodiment, the usage unit 4 includes an indoor fan 43 for supplying indoor air after sucking indoor air into the unit and exchanging heat, and flows through the indoor air and usage-side heat exchanger 41. It is possible to exchange heat with the refrigerant. The indoor fan 43 is driven by a fan motor 43a.
Further, the usage unit 4 includes a usage-side control unit 47 that controls the operation of each unit constituting the usage unit 4. The use-side control unit 47 includes a microcomputer, a memory, and the like provided for controlling the use unit 4, and a remote controller (not shown) for individually operating the use unit 4. Control signals and the like can be exchanged between them, and control signals and the like can be exchanged with the heat source unit 2.

(3) Configuration of Heat Source Unit The heat source unit 2 is installed outside a building such as a rooftop, for example. The heat source unit 2 is connected to the usage unit 4 via the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7, and constitutes a refrigerant circuit 10 between the usage units 4.
Next, the configuration of the heat source unit 2 will be described. The heat source unit 2 mainly includes a heat source side refrigerant circuit 10 b that constitutes a part of the refrigerant circuit 10. The heat source side refrigerant circuit 10b mainly includes a compressor 21, a four-way switching valve 22 as a switching mechanism, a heat source side heat exchanger 23, an expansion valve 24 as an expansion mechanism, a liquid side closing valve 25, A gas-side closing valve 26.

The compressor 21 is a compressor whose operating capacity can be varied. In this embodiment, the compressor 21 is a positive displacement compressor driven by a motor 21a controlled by an inverter. In the present embodiment, the number of the compressors 21 is only one. However, the present invention is not limited to this, and even if two or more compressors are connected in parallel according to the number of units used, etc. Good.
The four-way switching valve 22 is a valve for switching the refrigerant circulation direction. The gas side end of the heat source side heat exchanger 23, the gas side end of the use side heat exchanger 41, the suction side end of the compressor 21, and the compression It is connected to the discharge side end of the machine 21. During the cooling operation, the four-way switching valve 22 uses the heat source side heat exchanger 23 as a condenser for the refrigerant discharged from the compressor 21, and the use side heat exchanger 41 as the refrigerant that has been decompressed by the expansion valve 24. In order to function as a compressor, the refrigerant discharged from the compressor 21 is circulated in the order of the heat source side heat exchanger 23, the expansion valve 24, and the use side heat exchanger 41 in a first switching state (four-way switching valve 22 in FIG. 1). (See the solid line). In the heating operation, the four-way switching valve 22 uses the use-side heat exchanger 41 as a condenser for the refrigerant discharged from the compressor 21, and the heat source-side heat exchanger 23 is a refrigerant whose pressure is reduced by the expansion valve 24. In order to function as an evaporator, the refrigerant discharged from the compressor 21 is circulated in the order of the use side heat exchanger 41, the expansion valve 24, and the heat source side heat exchanger 23 in the second switching state (four-way switching in FIG. 1). (See the dashed line of the valve 22). That is, the four-way switching valve 22 is a valve that can be switched between a first switching state and a second switching state.

  In the present embodiment, the heat source side heat exchanger 23 is a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, and functions as a refrigerant condenser during cooling operation. It is a heat exchanger that functions as a refrigerant evaporator during heating operation. The gas side of the heat source side heat exchanger 23 is connected to the four-way switching valve 22, and the liquid side thereof is connected to the liquid refrigerant communication pipe 6. The type of the heat source side heat exchanger 23 is not limited to the cross fin type fin-and-tube type heat exchanger, and various types can be used. Further, the heat source of the heat source side heat exchanger 23 is not limited to outdoor air, and may be water.

The expansion valve 24 decompresses the refrigerant that is condensed in the heat source side heat exchanger 23 during the cooling operation and is sent to the use side heat exchanger 41, and is condensed in the use side heat exchanger 41 during the heating operation and is condensed in the heat source side heat exchanger. 23 is an electric expansion valve that depressurizes the refrigerant sent to 23.
In the present embodiment, the heat source unit 2 includes an outdoor fan 27 for sucking outdoor air into the unit, supplying the outdoor air to the heat source side heat exchanger 23, and then discharging the outdoor air to the outdoor side. It is possible to exchange heat with the refrigerant flowing through the heat exchanger 23. The outdoor fan 27 is driven by a fan motor 27a.

The liquid side shutoff valve 25 and the gas side shutoff valve 26 are valves provided at connection ports with external devices and pipes (specifically, the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7). The liquid side closing valve 25 is connected to the heat source side heat exchanger 23. The gas side closing valve 26 is connected to the four-way switching valve 22.
Further, the heat source unit 2 is provided with a high pressure / low pressure sensor 29 as a pressure detecting mechanism for detecting the pressure of the refrigerant flowing between the four-way switching valve 22 and the use side heat exchanger 41. The high pressure / low pressure sensor 29 detects the refrigerant pressure on the suction side of the compressor 21 when the four-way switching valve 22 is in the first switching state, and when the four-way switching valve 22 is in the second switching state. The refrigerant pressure on the discharge side of the compressor 21 can be detected.

  The heat source unit 2 includes a heat source side control unit 28 that controls the operation of each unit constituting the heat source unit 2. The heat source side control unit 28 includes a microcomputer and a memory provided for controlling the heat source unit 2, and an inverter circuit for controlling the motor 21 a, and the usage side control unit of the usage unit 4. A control signal and the like can be exchanged with 47.

  As described above, the use-side refrigerant circuit 10a, the heat-source-side refrigerant circuit 10b, and the refrigerant communication pipes 6 and 7 are connected to constitute the refrigerant circuit 10 of the air conditioner 1. The air conditioner 1 according to the present embodiment performs the operation by switching between the cooling operation and the heating operation by the four-way switching valve 22 by the control unit 8 including the heat source side control unit 28 and the use side control unit 47. The devices of the heat source unit 2 and the usage unit 4 are controlled according to the operation load of the usage unit 4.

(4) Operation | movement of an air conditioning apparatus Next, operation | movement of the air conditioning apparatus 1 of this embodiment is demonstrated.
As the operation of the air conditioner 1 of the present embodiment, the refrigerant discharged from the compressor 21 with the four-way switching valve 22 in the first switching state is used as the heat source side heat exchanger 23, the expansion valve 24, and the use side heat exchanger. The cooling operation as a refrigeration cycle operation that circulates in the order of 41, the refrigerant discharged from the compressor 21 with the four-way switching valve 22 in the second switching state, the use side heat exchanger 41, the expansion valve 24, and the heat source side heat exchange Heating operation as a refrigeration cycle operation that circulates in the order of the vessel 23 can be performed.

Hereinafter, each operation of the air conditioner 1 will be described.
(A) Cooling operation During the cooling operation, the four-way switching valve 22 is in the first switching state (that is, the state shown by the solid line in FIG. 1). Moreover, the liquid side closing valve 25 and the gas side closing valve 26 are opened, and the opening degree of the expansion valve 24 is adjusted.

  When the compressor 21, the outdoor fan 27, and the indoor fan 43 are operated in the state of the refrigerant circuit 10, the low-pressure gas refrigerant is sucked into the compressor 21 and compressed to be discharged as high-pressure gas refrigerant. This high-pressure gas refrigerant is sent to the heat source side heat exchanger 23 via the four-way switching valve 22, exchanges heat with the outdoor air supplied by the outdoor fan 27, and is condensed to form a high-pressure liquid refrigerant. Become. This high-pressure liquid refrigerant is decompressed by the expansion valve 24 to become a low-pressure gas-liquid two-phase refrigerant, and then passes through the liquid-side closing valve 25 and the liquid refrigerant communication pipe 6 to the use unit 4. Sent.

  Then, the low-pressure gas-liquid two-phase refrigerant sent to the usage unit 4 is sent to the usage-side heat exchanger 41 and is evaporated by exchanging heat with indoor air supplied by the indoor fan 43. It becomes a gas refrigerant. This low-pressure gas refrigerant is sent to the heat source unit 2 via the gas refrigerant communication pipe 7 and is again sucked into the compressor 21 via the gas-side closing valve 26 and the four-way switching valve 22.

  Here, in the above-described operation, the capacity control of the compressor 21 is performed based on the pressure value detected by the high pressure / low pressure sensor 29. More specifically, in order to make the evaporation temperature of the refrigerant constant, the compressor 21 is set so that the pressure value detected by the high-pressure / low-pressure sensor 29 that is a pressure value corresponding to the evaporation temperature of the refrigerant becomes constant. The capacity of the compressor 21 is controlled by changing the frequency of the motor 21a that drives the compressor. For example, when the pressure value detected by the high-pressure / low-pressure sensor 29 tends to increase, control for increasing the frequency of the motor 21a (that is, control for increasing the operating capacity of the compressor 21) is performed to evaporate the refrigerant. When the temperature is kept constant and the pressure value detected by the high pressure / low pressure sensor 29 tends to be low, control to lower the frequency of the motor 21a (that is, control to lower the operating capacity of the compressor 21) is performed. Make the evaporation temperature of the refrigerant constant.

  Further, in the operation performed immediately after the opening operation of the closing valves 25 and 26 as in the trial operation after the installation of the apparatus, the first switching of the four-way switching valve 22 is performed without forgetting the opening operation of the closing valves 25 and 26. A refrigeration cycle operation may be performed. However, in this air conditioner 1, since the high pressure / low pressure combined pressure sensor 29 is provided, based on the pressure value detected by the high pressure / low pressure combined pressure sensor 29 (specifically, the closing valves 25, 26 are closed). When in the state, based on the fact that the refrigerant pressure on the suction side of the compressor 21 falls below a predetermined value), whether or not the closing valves 25 and 26 are in the closed state (hereinafter referred to as opening / closing abnormality). Can be detected.

(B) Heating operation During the heating operation, the four-way switching valve 22 is in the second switching state (that is, the state indicated by the broken line in FIG. 1). Moreover, the liquid side closing valve 25 and the gas side closing valve 26 are opened, and the opening degree of the expansion valve 24 is adjusted.
When the compressor 21, the outdoor fan 27, and the indoor fan 43 are operated in the state of the refrigerant circuit 10, the low-pressure gas refrigerant is sucked into the compressor 21 and compressed to be discharged as high-pressure gas refrigerant. It is sent to the utilization unit 4 via the path switching valve 22, the gas side closing valve 26 and the gas refrigerant communication pipe 7.

  The high-pressure gas refrigerant sent to the use unit 4 is condensed by exchanging heat with room air in the use-side heat exchanger 41 to become a high-pressure liquid refrigerant, and then passes through the liquid refrigerant communication pipe 6. Then, after being sent to the heat source unit 2 and passing through the liquid-side closing valve 25, the pressure is reduced by the expansion valve 24 to become a low-pressure gas-liquid two-phase refrigerant. This low-pressure gas-liquid two-phase refrigerant flows into the heat source side heat exchanger 23, exchanges heat with the outdoor air supplied by the outdoor fan 27, is evaporated to become a low-pressure gas refrigerant, and the four-way switching valve Then, the air is again sucked into the compressor 21 via 22.

  Here, in the above-described operation, the capacity control of the compressor 21 is performed based on the pressure value detected by the high pressure / low pressure sensor 29. More specifically, in order to make the condensing temperature of the refrigerant constant, the compressor 21 is set so that the pressure value detected by the high pressure / low pressure sensor 29 which is a pressure value corresponding to the condensing temperature of the refrigerant becomes constant. The capacity of the compressor 21 is controlled by changing the frequency of the motor 21a that drives the compressor. For example, when the pressure value detected by the high pressure / low pressure sensor 29 tends to increase, the control of lowering the frequency of the motor 21a (ie, the control of lowering the operating capacity of the compressor 21) is performed to condense the refrigerant. When the temperature is kept constant and the pressure value detected by the high pressure / low pressure sensor 29 tends to be low, control to increase the frequency of the motor 21a (that is, control to increase the operating capacity of the compressor 21) is performed. Keep the refrigerant condensing temperature constant.

  Further, the refrigerant pressure on the discharge side of the compressor 21 may become abnormally high for some reason. However, since the air conditioner 1 is provided with the high-pressure / low-pressure pressure sensor 29, based on the pressure value detected by the high-pressure / low-pressure pressure sensor 29 (specifically, on the discharge side of the compressor 21). Whether or not the refrigerant pressure on the discharge side of the compressor 21 is abnormally high (hereinafter referred to as discharge pressure abnormality) can be detected based on the fact that the refrigerant pressure rises above a predetermined value).

(5) Features of the air conditioner and the heat source unit used therein The air conditioner 1 of the present embodiment has the following features.
(A)
In the air conditioner 1 of this embodiment and the heat source unit 2 used therein, as a pressure detection mechanism that detects the pressure of the refrigerant flowing between the four-way switching valve 22 as a switching mechanism and the use side heat exchanger 41. Since the high pressure / low pressure sensor 29 is provided, the pressure value of the refrigerant corresponding to the evaporation temperature of the refrigerant can be detected when the four-way switching valve 22 is in the first switching state, and the four-way switching valve. When 22 is in the second switching state, the refrigerant pressure value corresponding to the refrigerant condensing temperature can be detected.

  As a result, the operation control of the air conditioner 1 using the refrigerant evaporation temperature in the refrigeration cycle operation in the first switching state such as the cooling operation is performed only by the high pressure / low pressure sensor 29 (here, the refrigerant evaporation temperature is adjusted). Operation control of the air conditioner 1 using the condensation temperature of the refrigerant in the refrigeration cycle operation in the second switching state such as the heating operation (here, the capacity control of the compressor 21 to make it constant) Therefore, it is possible to achieve both cost reduction and ensuring controllability.

  Moreover, the high pressure / low pressure sensor 29 has a conventional suction pipe of the compressor 21 (that is, between the four-way switching valve 22 and the suction side end of the compressor 21) and a discharge pipe (that is, the compressor 21). Compared with the case where a pressure sensor is provided between the discharge side end of the compressor 21 and the four-way switching valve 22), the refrigerant pressure can be detected on the side closer to the use side heat exchanger 41, and therefore more accurate. Operation control of the air conditioner 1 can be performed using a proper evaporation temperature or condensation temperature.

(B)
In the air conditioner 1 of this embodiment and the heat source unit 2 used therein, the opening operation of the closing valves 25 and 26 is performed in the operation performed immediately after the opening operation of the closing valves 25 and 26 as in the test operation after installation of the device. Even if the refrigeration cycle operation is performed with the four-way switching valve 22 in the first switching state, the opening / closing abnormality of the closing valves 25 and 26 is based on the pressure value detected by the high pressure / low pressure sensor 29. Can be detected. Thereby, the compressor 21 can be protected only by the high pressure / low pressure sensor 29.

  Further, in the air conditioner 1 and the heat source unit 2 used therefor, in the refrigeration cycle operation in which the four-way switching valve 22 is set to the second switching state such as the heating operation, it is detected by the high pressure / low pressure sensor 29. An abnormal discharge pressure of the compressor 21 can be detected based on the pressure value. Thereby, the compressor 21 can be protected only by the high pressure / low pressure sensor 29.

(6) Other Embodiments While the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments and can be changed without departing from the scope of the invention. It is.
For example, in the above-described embodiment, the example in which the present invention is applied to an air conditioner having a configuration in which one usage unit is connected to one heat source unit has been described. A configuration in which multiple usage units are connected to a heat source unit, a configuration in which one usage unit is connected to multiple heat source units, or a configuration in which multiple usage units are connected to multiple heat source units You may apply this invention to the air conditioning apparatus which has.

  By using the present invention, in an air conditioner equipped with a refrigerant circuit that can be switched between heating and cooling by changing the refrigerant circulation direction and a heat source unit of the air conditioner used therefor, both cost reduction and ensuring controllability are achieved. Can be made.

It is a schematic block diagram of the air conditioning apparatus concerning one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Heat source unit 6 Liquid refrigerant communication pipe 7 Gas refrigerant communication pipe 10 Refrigerant circuit 21 Compressor 22 Four-way switching valve (switching mechanism)
23 heat source side heat exchanger 24 expansion valve (expansion mechanism)
25 Liquid side shutoff valve 26 Gas side shutoff valve 29 Pressure sensor for both high and low pressure (pressure detection mechanism)
41 Use side heat exchanger

Claims (5)

A compressor (21) for compressing the refrigerant;
A heat source side heat exchanger (23);
A use side heat exchanger (41);
An expansion mechanism (24) connected between the liquid side end of the heat source side heat exchanger and the liquid side end of the utilization side heat exchanger;
Connected to the gas side end of the heat source side heat exchanger, the gas side end of the utilization side heat exchanger, the suction side end of the compressor, and the discharge side end of the compressor, and discharged from the compressor A first switching state in which refrigerant is circulated in the order of the heat source side heat exchanger, the expansion mechanism, and the usage side heat exchanger; and the refrigerant discharged from the compressor, the usage side heat exchanger, the expansion mechanism, and the A switching mechanism (22) capable of switching to a second switching state in which the heat source side heat exchanger is circulated in order;
A refrigerant circuit (10) connected to
A pressure detection mechanism (29) for detecting the pressure of the refrigerant flowing between the switching mechanism and the use side heat exchanger;
An air conditioner (1) comprising: When the switching mechanism (22) is in the first switching state, capacity control of the compressor (21) is performed based on a pressure value detected by the pressure detection mechanism (29),
When the switching mechanism (22) is in the second switching state, capacity control of the compressor (21) is performed based on a pressure value detected by the pressure detection mechanism (29).
The air conditioner (1) according to claim 1.   The discharge pressure abnormality of the compressor (21) is detected based on the pressure value detected by the pressure detection mechanism (29) when the switching mechanism (22) is in the second switching state. The air conditioning apparatus (1) described. The refrigerant circuit (10) includes the heat source unit (2) including the compressor (21), the heat source side heat exchanger (23), the expansion mechanism (24), and the switching mechanism (22); The utilization unit (4) including the side heat exchanger (41) is configured to be connected via the liquid refrigerant communication pipe (6) and the gas refrigerant communication pipe (7).
The heat source unit is a liquid side shut-off valve (25) connected between the expansion mechanism connected to the liquid side end of the use side heat exchanger via the liquid refrigerant communication pipe and the liquid refrigerant communication pipe. And a gas side shut-off valve (26) connected between one end of the switching mechanism connected to the gas side end of the use side heat exchanger via the gas refrigerant communication pipe and the gas refrigerant communication pipe. In addition,
Detecting an abnormal opening / closing of the closing valve based on a pressure value detected by the pressure detection mechanism (29);
The air conditioner (1) according to claim 2 or 3. A compressor (21) which is a heat source unit of an air conditioner connected to the utilization unit (4) via a liquid refrigerant communication pipe (6) and a gas refrigerant communication pipe (7), and compresses the refrigerant;
A heat source side heat exchanger (23);
A liquid side stop valve (25) connected to the liquid refrigerant communication pipe;
A gas-side stop valve (26) connected to the gas refrigerant communication pipe;
Connected to the gas side end of the heat source side heat exchanger, the gas side stop valve, the suction side end of the compressor, and the discharge side end of the compressor, the discharge side end of the compressor and the heat source side heat A first switching state connecting the gas side end of the exchanger and connecting the suction side end of the compressor and the gas side shut-off valve; and connecting the discharge side end of the compressor and the gas side shut-off valve And a switching mechanism (22) capable of switching to a second switching state connecting the suction side end of the compressor and the gas side end of the heat source side heat exchanger;
A pressure detection mechanism (29) for detecting the pressure of the refrigerant flowing between the switching mechanism and the gas side shut-off valve;
A heat source unit (2) of an air conditioner comprising:

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