Air conditioning device and heat source unit

Abstract

An air conditioning device according to one embodiment of the present invention comprises a refrigerant circuit, a refrigerant sensor, and a control unit. The refrigerant circuit has a heat source unit that has a compressor and a heat source-side heat exchanger, a utilization-side unit that has a utilization-side heat exchanger, a liquid pipe and a gas pipe that connect the heat source-side heat exchanger and the utilization-side heat exchanger, an expansion valve that is connected to the liquid pipe, and an opening / closing valve that is connected to the gas pipe. The refrigerant sensor is positioned in the gas pipe and detects a condition of a refrigerant flowing through the gas pipe. The control unit controls each of the compressor, the expansion valve, and the opening / closing valve. The control unit determines an opening / closing condition of the opening / closing valve on the basis of opening / closing operation instructions with regard to the opening / closing valve and the detection result from the refrigerant sensor.

Description

Air conditioning equipment and heat source units

[0001] The present invention relates to an air conditioner and a heat source unit in which a plurality of indoor units are connected in parallel to one outdoor unit.

[0002] For example, Patent Document 1 discloses an air conditioner in which an indoor unit (chiller unit) equipped with a water-refrigerant heat exchanger that exchanges heat between a refrigerant and water and at least one indoor unit (direct expansion indoor unit) equipped with an air-refrigerant heat exchanger that exchanges heat between a refrigerant and air are connected in parallel. In this type of air conditioner, each indoor unit has an expansion valve disposed in a liquid refrigerant pipe connected to one end of the heat exchanger and an on-off valve disposed in a gas refrigerant pipe connected to the other end of the heat exchanger. When only one of the indoor units is operated, for example during heating operation, the expansion valves and on-off valves are operated as follows:

[0003] In the indoor unit that is operating (hereinafter also referred to as the operating indoor unit), the expansion valve is adjusted to an opening degree according to the required capacity, and the on-off valve is fully open. On the other hand, in the indoor unit that is stopped (hereinafter also referred to as the stopped indoor unit), the expansion valve is fully open to prevent refrigerant from accumulating in the heat exchanger, and the on-off valve is fully closed to prevent refrigerant from flowing into the heat exchanger.

[0004] JP 2009-236392 A

[0005] However, in this type of air conditioner, if the on-off valve fails during the heating cycle, the following problems may occur.

[0006] For example, if the on-off valve on the stopped indoor unit does not close during heating operation, refrigerant flowing into the indoor heat exchanger of the stopped indoor unit condenses into liquid refrigerant. This liquid refrigerant then flows through the fully open expansion valve into the outdoor heat exchanger. As a result, the temperature of the refrigerant drawn into the compressor drops, resulting in a drop in the temperature of the refrigerant discharged from the compressor (discharge temperature). If the expansion valve on the operating indoor unit is adjusted to achieve a predetermined target discharge temperature during heating operation, the valve is narrowed to adjust the lowered discharge temperature to the target temperature. As a result, more refrigerant flows into the stopped indoor unit, resulting in a larger amount of liquid refrigerant flowing into the outdoor heat exchanger. If the amount of liquid refrigerant flowing into the outdoor heat exchanger increases, the liquid refrigerant may not completely evaporate in the outdoor heat exchanger and flow into the compressor, a condition known as liquid backflow, which could lead to compressor failure.

[0007] Furthermore, if the on-off valve on the driver's indoor unit does not open during heating operation, the on-off valve on the stopped indoor unit also closes, stopping the flow of refrigerant through the refrigerant circuit. As a result, the pressure of the refrigerant discharged from the compressor (discharge pressure) rises sharply, and control is executed to stop the compressor (high-pressure protection control) to protect it from high pressure. However, if the on-off valve on the driver's indoor unit does not open even after the compressor is restarted, the high-pressure protection control will be executed again, causing the compressor to start and stop frequently, which will shorten its lifespan.

[0008] In view of the above circumstances, an object of the present invention is to provide an air conditioner and a heat source unit that can detect malfunctions in an on-off valve and prevent a decrease in the reliability of a compressor.

[0009] An air conditioning apparatus according to one aspect of the present invention includes a refrigerant circuit, a refrigerant sensor, and a control unit. The refrigerant circuit includes a heat source unit having a compressor and a heat source-side heat exchanger, a user-side unit having a user-side heat exchanger, a liquid pipe and a gas pipe connecting the heat source-side heat exchanger and the user-side heat exchanger, an expansion valve connected to the liquid pipe, and an on-off valve connected to the gas pipe. The refrigerant sensor is disposed in the gas pipe and detects the state of the refrigerant flowing through the gas pipe. The control unit controls the compressor, the expansion valve, and the on-off valve. The control unit determines the on-off state of the on-off valve based on an on-off operation command for the on-off valve and the detection result of the refrigerant sensor.

[0010] A heat source unit according to one aspect of the present invention includes a compressor, a heat source side heat exchanger, a first liquid pipe connection portion connected to a first indoor heat exchanger in a first indoor unit, a second liquid pipe connection portion connected to a second indoor heat exchanger in a second indoor unit, a first gas pipe connection portion connected to the first indoor heat exchanger, a second gas pipe connection portion connected to the second indoor heat exchanger, a first outdoor unit gas pipe connecting one end of the heat source side heat exchanger to the first gas pipe connection portion, a second outdoor unit gas pipe connecting one end of the heat source side heat exchanger to the second gas pipe connection portion, a first outdoor unit liquid pipe connecting the other end of the heat source side heat exchanger to the first liquid pipe connection portion, and a second outdoor unit liquid pipe connecting the other end of the heat source side heat exchanger to the second liquid pipe connection portion. a first expansion valve disposed in the first outdoor unit liquid pipe, a second expansion valve disposed in the second outdoor unit liquid pipe, a first on-off valve disposed in the first outdoor unit gas pipe, a second on-off valve disposed in the second outdoor unit gas pipe, a first refrigerant sensor disposed in the first outdoor unit gas pipe between the first on-off valve and the first gas pipe connection and configured to detect a state of refrigerant flowing through the first outdoor unit gas pipe, a second refrigerant sensor disposed in the second outdoor unit gas pipe between the second on-off valve and the second gas pipe connection and configured to detect a state of refrigerant flowing through the second outdoor unit gas pipe, and a control unit that controls the compressor, the first expansion valve, the second expansion valve, the first on-off valve, and the second on-off valve, respectively. When operating one of the first indoor unit and the second indoor unit and stopping the other, the control unit determines the on-off states of the first on-off valve and the second on-off valve based on on-off operation commands for the first on-off valve and the second on-off valve and detection results of the first refrigerant sensor and the second refrigerant sensor.

[0011] According to the present invention, a malfunction of an on-off valve can be detected to suppress a decrease in the reliability of the compressor.

[0012] Fig. 6 is a refrigerant circuit diagram showing an example of the configuration of an air conditioner according to a first embodiment of the present invention. Fig. 7 is a system diagram showing an example of the configuration of a hot water supply device. Fig. 8 is a block diagram showing the configuration of a control unit. Fig. 9 is a flowchart showing an example of the processing procedure relating to the operation determination processing of an on-off valve executed by the control unit during heating operation or hot water supply operation. Fig. 10 is a side view showing a part of the refrigerant piping inside a heat source unit. Fig. 11 is a refrigerant circuit diagram showing an example of the configuration of an air conditioner according to a second embodiment of the present invention. Fig. 12 is a flowchart showing an example of the processing procedure relating to the operation determination processing of an on-off valve executed by the control unit in the air conditioner shown in Fig. 6

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] <First embodiment> Fig. 1 is a refrigerant circuit diagram showing an example of the configuration of an air conditioning apparatus 100 according to one embodiment of the present invention. The entire air conditioning apparatus 100 of this embodiment will be described briefly below with reference to Fig. 1 .

[0015] 1, the air conditioner 100 includes a refrigerant circuit 10. The refrigerant circuit 10 includes a heat source unit 1, a user-side unit 2, a liquid pipe 3 and a gas pipe 4 connecting an outdoor heat exchanger 13 in the heat source unit 1 with the user-side unit 2, an expansion valve 5 connected to the liquid pipe 3, and an on-off valve 6 connected to the gas pipe 4.

[0016] The heat source unit 1 corresponds to an outdoor unit. The user-side unit 2 corresponds to an indoor unit. In this embodiment, the user-side unit 2 includes a first indoor unit 2A having a first indoor heat exchanger 21A as a user-side heat exchanger, and a second indoor unit 2B having a second indoor heat exchanger 21B as a user-side heat exchanger. The number of user-side units 2 may be one or three or more.

[0017] The heat source unit 1 has a compressor 11, a four-way valve 12, an outdoor heat exchanger 13 as a heat source side heat exchanger, an outdoor fan 13F, an accumulator 14, a first liquid pipe connection part 311, a second liquid pipe connection part 312, a first gas pipe connection part 411, and a second gas pipe connection part 412.

[0018] The compressor 11 is a variable capacity compressor with a variable operating capacity driven by a motor (not shown) whose rotation speed is controlled by an inverter. The refrigerant discharge side of the compressor 11 is connected to port a of the four-way valve 12 via a discharge pipe 15. The refrigerant suction side of the compressor 11 is connected to the refrigerant outflow side of the accumulator 14 via a suction pipe 18.

[0019] The four-way valve 12 is a flow path switching valve that switches the refrigerant flow direction in the refrigerant circuit 10 and has four ports a, b, c, and d. As described above, port a is connected to the refrigerant discharge side of the compressor 11 via discharge piping 15. Port b is connected to one refrigerant inlet / outlet at one end of the outdoor heat exchanger 13 via refrigerant piping 16. Port c is connected to the refrigerant inlet / outlet at one end of the accumulator 14 via refrigerant piping 17. Port d is connected to one refrigerant inlet / outlet at one end of the first indoor heat exchanger 21A via a first gas pipe 4A that is part of the gas pipe 4, and is also connected to one refrigerant inlet / outlet at one end of the second indoor heat exchanger 21B via a second gas pipe 4B that is part of the gas pipe 4.

[0020] The outdoor heat exchanger 13 exchanges heat between the refrigerant and outside air taken into the heat source unit 1 by the rotation of the outdoor fan 13F. As described above, one end of the outdoor heat exchanger 13 is connected to port b of the four-way valve 12 by refrigerant piping 16. The other end of the outdoor heat exchanger 13 is connected to the other refrigerant inlet / outlet, which is the other end of the first indoor heat exchanger 21A, by a first liquid pipe 3A that is part of the liquid pipe 3, and is also connected to the other refrigerant inlet / outlet, which is the other end of the second indoor heat exchanger 21B, by a second liquid pipe 3B that is part of the liquid pipe 3.

[0021] The outdoor fan 13F is disposed near the outdoor heat exchanger 13. The outdoor fan 13F is rotated by a fan motor (not shown) to take in outside air from an intake port (not shown) of the heat source unit 1, exchange heat with the refrigerant in the outdoor heat exchanger 13, and release the outside air from an outlet port (not shown) of the heat source unit 1 to the outside of the heat source unit 1.

[0022] The liquid pipe 3 and the gas pipe 4 are refrigerant pipes that connect the outdoor heat exchanger 13 to the first indoor heat exchanger 21A and the second indoor heat exchanger 21B.

[0023] The liquid pipe 3 includes a first liquid pipe 3A and a second liquid pipe 3B. As described above, the first liquid pipe 3A connects the other end of the outdoor heat exchanger 13 to the other end of the first indoor heat exchanger 21A. As described above, the second liquid pipe 3B connects the other end of the outdoor heat exchanger 13 to the other end of the second indoor heat exchanger 21B.

[0024] The first liquid pipe 3A has an outdoor unit liquid pipe 31, a first outdoor unit liquid branch pipe 31A, and a first liquid refrigerant pipe 32A. The outdoor unit liquid pipe 31 is connected to the other end of the outdoor heat exchanger 13 and has a branch point C1 of the first outdoor unit liquid branch pipe 31A and the second outdoor unit liquid branch pipe 31B. The first outdoor unit liquid branch pipe 31A connects the branch point C1 of the outdoor unit liquid pipe 31 and the first liquid pipe connection part 311. The first liquid refrigerant pipe 32A connects the first liquid pipe connection part 311 and the other end of the first indoor heat exchanger 21A.

[0025] The second liquid pipe 3B has an outdoor unit liquid pipe 31, a second outdoor unit liquid branch pipe 31B, and a second liquid refrigerant pipe 32B. The second outdoor unit liquid branch pipe 31B connects the branch point C1 of the outdoor unit liquid pipe 31 and the second liquid pipe connection part 312. The second liquid refrigerant pipe 32B connects the second liquid pipe connection part 312 and the other end of the second indoor heat exchanger 21B.

[0026] The gas pipe 4 includes a first gas pipe 4A and a second gas pipe 4B. The first gas pipe 4A connects the one end of the outdoor heat exchanger 13 to the one end of the first indoor heat exchanger 21A. The second gas pipe 4B connects the one end of the outdoor heat exchanger 13 to the one end of the second indoor heat exchanger 21B.

[0027] The first gas pipe 4A has an outdoor unit gas pipe 41, a first outdoor unit gas branch pipe 41A, and a first gas refrigerant pipe 42A. The outdoor unit gas pipe 41 is connected to the one end of the outdoor heat exchanger 13 via the four-way valve 12 and the refrigerant pipe 16, and has a branch point C2 from the first outdoor unit gas branch pipe 41A and the second outdoor unit gas branch pipe 41B. The first outdoor unit gas branch pipe 41A connects the branch point C2 of the outdoor unit gas pipe 41 to the first gas pipe connection part 411. The first gas refrigerant pipe 42A connects the first gas pipe connection part 411 to the one end of the first indoor heat exchanger 21A.

[0028] The second gas pipe 4B has an outdoor unit gas pipe 41, a second outdoor unit gas branch pipe 41B, and a second gas refrigerant pipe 42B. The second outdoor unit gas branch pipe 41B connects the branch point C2 of the outdoor unit gas pipe 41 and the second gas pipe connection part 412. The second gas refrigerant pipe 42B connects the second gas pipe connection part 412 and the one end of the second indoor heat exchanger 21B.

[0029] The expansion valves 5 include a first expansion valve 5A and a second expansion valve 5B. The first expansion valve 5A is disposed in the first liquid pipe 3A, and the second expansion valve 5B is disposed in the second liquid pipe 3B. In this embodiment, the first expansion valve 5A is disposed in the first outdoor unit liquid branch pipe 31A, and the second expansion valve 5B is disposed in the second outdoor unit liquid branch pipe 31B.

[0030] The first expansion valve 5A and the second expansion valve 5B are electronic expansion valves whose openings are adjusted by applying a DC voltage, for example, and are controlled based on the number of pulses applied to a stepping motor (not shown).

[0031] The first expansion valve 5A reduces the pressure of the refrigerant flowing through the first liquid pipe 3A. The opening degree of the first expansion valve 5A is adjusted according to the operating capacity required by the first indoor unit 2A. The second expansion valve 5B reduces the pressure of the refrigerant flowing through the second liquid pipe 3B. The opening degree of the second expansion valve 5B is adjusted according to the operating capacity required by the second indoor unit 2B.

[0032] The on-off valve 6 includes a first on-off valve 6A and a second on-off valve 6B. The first on-off valve 6A is disposed in the first gas pipe 4A, and the second on-off valve 6B is disposed in the second gas pipe 4B. In this embodiment, the first on-off valve 6A is disposed in the first outdoor unit gas branch pipe 41A, and the second on-off valve 6B is disposed in the second outdoor unit gas branch pipe 41B.

[0033] The first on-off valve 6A is an on-off valve capable of blocking the flow of refrigerant in the first gas pipe 4A. The first on-off valve 6A is open when the first indoor unit 2A is operating and closed when the first indoor unit 2A is stopped. The second on-off valve 6B is an on-off valve capable of blocking the flow of refrigerant in the second gas pipe 4B. The second on-off valve 6B is open when the second indoor unit 2B is operating and closed when the indoor unit 2B is stopped.

[0034] The first on-off valve 6A and the second on-off valve 6B are, for example, DC solenoid valves that open and close when a direct current is passed through them. In this embodiment, the first on-off valve 6A and the second on-off valve 6B are normally open solenoid valves that close when a current is passed through them. Alternatively, the first on-off valve 6A and the second on-off valve 6B may be AC ​​solenoid valves that open and close when a direct current is passed through them, or may be normally closed solenoid valves that open when a current is passed through them.

[0035] The first indoor unit 2A has a first indoor heat exchanger 21A and an indoor fan 21FA, and the second indoor unit 2B has a second indoor heat exchanger 21B.

[0036] In this embodiment, the first indoor heat exchanger 21A is an air-refrigerant heat exchanger that exchanges heat between the air (indoor air) in the indoor space where the first indoor unit 2A is installed and the refrigerant. On the other hand, the second indoor unit 2B is, for example, the water heater 500 shown in Fig. 2, and the second indoor heat exchanger 21B is a water-refrigerant heat exchanger that exchanges heat between the water circulating through the water heater 500 and the refrigerant.

[0037] 2 is a system diagram showing an example of the configuration when the second indoor unit 2B is used as a hot water supply device 500. The hot water supply device 500 has a hot water storage tank 51, a water pipe 52 that supplies city water to the hot water storage tank 51, a water circuit 50 including a pump 53 that circulates water between the hot water storage tank 51 and the second indoor heat exchanger (water-refrigerant heat exchanger) 21B, and a hot water supply pipe 54 that supplies hot water in the hot water storage tank 51 to the outside. A mixing valve 55 is provided in the hot water supply pipe 54 to mix the hot water flowing out of the hot water storage tank 51 with water in the water pipe 52.

[0038] The second indoor unit 2B is not limited to the above example, and may be a panel heater for floor heating instead of the hot water storage tank 51, or may be a fan coil unit (FCU) further equipped with a water-air heat exchanger that exchanges heat between the water circulating in the water circuit and the indoor air. Furthermore, the second indoor heat exchanger 21B may be a heat exchange section disposed inside the hot water storage tank 51, and the water stored in the hot water storage tank 51 may be heated by the refrigerant flowing in the heat exchange section.

[0039] Furthermore, the second indoor heat exchanger 21B may be an air-refrigerant heat exchanger like the first indoor heat exchanger 21A. That is, both the first indoor heat exchanger 21A and the second indoor heat exchanger 21B may be air-refrigerant heat exchangers, or at least one of the first indoor heat exchanger 21A and the second indoor heat exchanger 21B may be a water-refrigerant heat exchanger.

[0040] The indoor fan 21FA is disposed near the first indoor heat exchanger 21A. The indoor fan 21FA is rotated by a fan motor (not shown) to take in indoor air through an intake port (not shown) of the first indoor unit 2A, exchange heat with the refrigerant in the first indoor heat exchanger 21A, and release the indoor air into the room through an outlet port (not shown) of the first indoor unit 2A.

[0041] The air conditioning apparatus 100 is provided with various sensors. For example, in the heat source unit 1, the discharge piping 15 is provided with a high-pressure sensor 71 that detects the pressure of the refrigerant discharged from the compressor 11, and a discharge temperature sensor 72 that detects the temperature of the refrigerant discharged from the compressor 11. The suction piping 18 is provided with a low-pressure sensor 73 that detects the pressure of the refrigerant sucked into the compressor 11, and a suction temperature sensor 74 that detects the temperature of the refrigerant sucked into the compressor 11. The outdoor heat exchanger 13 is also provided with an outdoor heat exchanger temperature sensor 75 that detects the temperature of the refrigerant flowing through the outdoor heat exchanger 13. An outdoor air temperature sensor 76 that detects the temperature of the outdoor air flowing into the heat source unit 1, i.e., the outdoor air temperature, is provided near an intake port (not shown) of the heat source unit 1.

[0042] The first indoor unit 2A is provided with a first indoor heat exchanger temperature sensor 77A for detecting the temperature of the refrigerant flowing through the first indoor heat exchanger 21A, and a room temperature sensor 78 for detecting the indoor temperature. The second indoor unit 2B is provided with a second indoor heat exchanger temperature sensor 77B for detecting the temperature of the refrigerant flowing through the second indoor heat exchanger 21B, as well as a water temperature sensor 79a for detecting the temperature of water flowing into the second indoor heat exchanger 21B, a water temperature sensor 79b for detecting the temperature of water flowing out of the indoor heat exchanger 21B, and a hot water storage tank temperature sensor 79c for detecting the temperature of water stored in the hot water storage tank 51, as shown in FIG.

[0043] The air conditioning apparatus 100 further includes a first refrigerant sensor 84A and a second refrigerant sensor 84B as refrigerant sensors that detect the state of the refrigerant flowing through the gas pipes 4 (4A, 4B). The first refrigerant sensor 84A is a refrigerant temperature sensor that detects the temperature of the refrigerant flowing through the first gas pipe 4A, and the second refrigerant sensor 84B is a refrigerant temperature sensor that detects the temperature of the refrigerant flowing through the second gas pipe 4B. Alternatively, the first refrigerant sensor 84A and the second refrigerant sensor 84B may be refrigerant pressure sensors that detect the pressure of the refrigerant flowing through the gas pipes 4 (4A, 4B).

[0044] Specifically, the first refrigerant sensor 84A is disposed in the first gas pipe 4A between the first on-off valve 6A and the first indoor heat exchanger 21A, and the second refrigerant sensor 84B is disposed in the second gas pipe 4B between the second on-off valve 6B and the second indoor heat exchanger 21B. In particular, in this embodiment, the first refrigerant sensor 84A is disposed in the first outdoor unit gas branch pipe 41A between the first on-off valve 6A and the first gas pipe connection 411, and the second refrigerant sensor 84B is disposed in the second outdoor unit gas branch pipe 41B between the second on-off valve 6B and the second gas pipe connection 412. This will be described in detail later with reference to FIG. 5 .

[0045] The air conditioning apparatus 100 further includes a control unit 90. The control unit 90 is a heat source unit control device provided in the heat source unit 1, and is mounted on a control board stored in an electrical component box (not shown) of the heat source unit 1. Fig. 3 is a block diagram showing the configuration of the control unit 90. As shown in the figure, the control unit 90 includes a CPU (Central Processing Unit) 91, a memory unit 92, a communication unit 93, a sensor input unit 94, and a rotation speed detection unit 95.

[0046] The memory unit 92 is a non-volatile memory such as a flash memory, and stores the control program and control parameters of the heat source unit 1, detection values ​​corresponding to detection signals from various sensors, the control status of each device provided in the heat source unit 1 such as the compressor 11 and the outdoor fan 13F, and the control status of the first indoor unit 2A and the second indoor unit 2B obtained via the communication unit 93.

[0047] The communication unit 93 is an interface that communicates with the first indoor unit 2A and the second indoor unit 2B. The sensor input unit 94 takes in detection results from various sensors in the heat source unit 1 and outputs them to the CPU 91. The rotation speed detection unit 95 detects the rotation speed of the motor of the compressor 11 and outputs it to the CPU 91. The rotation speed detection unit 95 may be configured to directly detect the rotation speed of the motor using an encoder or the like attached to the drive shaft of the motor, or may be configured to detect the rotation speed of the motor from the drive current supplied to the motor. In the following description, the rotation speed of the compressor 11 refers to the rotation speed of the motor.

[0048] The CPU 91 is a control unit that controls each device of the heat source unit 1, including the compressor 11, by executing a program stored in the storage unit 92. The program is installed in advance in the control unit 90. Alternatively, the program may be installed via the Internet or the like.

[0049] The CPU 91 receives the detection results of the sensors in the heat source unit 1 described above via the sensor input unit 94. Furthermore, the CPU 91 receives control signals transmitted from the first indoor unit 2A and the second indoor unit 2B via the communication unit 93. The control signals transmitted from the first indoor unit 2A and the second indoor unit 2B include the operating capacities required by the first indoor unit 2A and the second indoor unit 2B. Based on the received detection results and control signals, the CPU 91 controls the drive of the compressor 11, the outdoor fan 13F, and the like, for example, by setting the command rotation speed, which is the rotation speed to be applied when driving these. Furthermore, the CPU 91 controls the switching of the four-way valve 12 based on the received detection results and control signals.

[0050] Furthermore, the CPU 91 issues opening / closing operation commands to control the opening degrees of the first expansion valve 5A and the second expansion valve 5B and the opening and closing of the first on-off valve 6A and the second on-off valve 6B, respectively, based on the captured detection results and control signals. In particular, in this embodiment, when the CPU 91 operates either the first indoor unit 2A or the second indoor unit 2B, it stops the other. In other words, the first indoor unit 2A and the second indoor unit 2B are not operated simultaneously, and only one of them is operated.

[0051] [Basic Operation of Air Conditioning Apparatus] Next, a description will be given of the basic operation of the air conditioning apparatus 100. Here, cooling operation, heating operation, and hot water supply operation will be described.

[0052] (Cooling Operation) When the air conditioning apparatus 100 performs cooling operation using the first indoor unit 2A, for example, the four-way valve 12 is switched to the state shown by the solid line in Figure 1, i.e., state 2, in which port a and port b are connected and port c and port d are connected. In addition, the second expansion valve 5B is fully closed, and the first on-off valve 6A and the second on-off valve 6B are both open. Adjustment of the opening of the first expansion valve 5A will be described later.

[0053] In this state, driving the compressor 11 causes refrigerant to circulate through the refrigerant circuit 10. At this time, the outdoor heat exchanger 13 functions as a condenser, and the first indoor heat exchanger 21A functions as an evaporator. Here, the second expansion valve 5B is fully closed to prevent refrigerant from flowing into the second indoor heat exchanger 21B of the second indoor unit 2B, whose operation is stopped. Furthermore, by opening the second on-off valve 6B, refrigerant accumulating between the second indoor heat exchanger 21B and the second on-off valve 6B flows out to the outdoor unit gas pipe 41 side as the compressor 11 is driven, thereby preventing refrigerant from accumulating between the second indoor heat exchanger 21B and the second on-off valve 6B.

[0054] The high-temperature, high-pressure refrigerant discharged from the compressor 11 flows into the four-way valve 12 through the discharge pipe 15, and then flows from the four-way valve 12 through the refrigerant pipe 16 into the outdoor heat exchanger 13. The refrigerant that has flowed into the outdoor heat exchanger 13 exchanges heat with outside air that has been drawn into the heat source unit 1 by the rotation of the outdoor fan 13F, and is condensed.

[0055] The refrigerant flowing out of the outdoor heat exchanger 13 flows through the outdoor unit liquid pipe 31 and the first outdoor unit liquid branch pipe 31A and is reduced in pressure as it passes through the first expansion valve 5A. The opening degree of the first expansion valve 5A is set so that the discharge temperature of the compressor 11 becomes the target discharge temperature. The refrigerant passing through the first expansion valve 5A flows through the first liquid refrigerant pipe 32A into the first indoor heat exchanger 21A, where it exchanges heat with indoor air and evaporates. The refrigerant flowing out of the first indoor heat exchanger 21A flows through the first gas refrigerant pipe 42A, the first outdoor unit gas branch pipe 41A, and the first on-off valve 6A in the open state to the outdoor unit gas pipe 41. The refrigerant flowing into the outdoor unit gas pipe 41 flows through the four-way valve 12, refrigerant pipe 17, accumulator 14, and suction pipe 18, and is drawn into the compressor 11 where it is compressed again.

[0056] (Heating operation) When the air conditioning apparatus 100 performs heating operation using the first indoor unit 2A, the four-way valve 12 is switched to the state shown by the dashed lines in Fig. 1, i.e., state 1, in which port a and port d are connected and port b and port c are connected. In addition, the second expansion valve 5B is fully opened, the first on-off valve 6A is opened, and the second on-off valve 6B is closed. Adjustment of the opening of the first expansion valve 5A will be described later.

[0057] In this state, driving the compressor 11 causes refrigerant to circulate through the refrigerant circuit 10. At this time, the outdoor heat exchanger 13 functions as an evaporator, and the first indoor heat exchanger 21A functions as a condenser. Here, closing the second on-off valve 6B prevents refrigerant from flowing into the second indoor heat exchanger 21B of the second indoor unit 2B, whose operation is stopped. Furthermore, fully opening the second expansion valve 5B causes the refrigerant remaining between the second indoor heat exchanger 21B and the second expansion valve 5B to flow out to the outdoor unit liquid pipe 31 as the compressor 11 is driven, thereby preventing refrigerant from accumulating between the second indoor heat exchanger 21B and the second expansion valve 5B.

[0058] The high-temperature, high-pressure refrigerant discharged from the compressor 11 flows through the discharge pipe 15 into the four-way valve 12, and then flows from the four-way valve 12 through the outdoor unit gas pipe 41, the first outdoor unit gas branch pipe 41A, the first on-off valve 6A in the fully open state, and the first gas refrigerant pipe 42A into the first indoor heat exchanger 21A. The refrigerant that has flowed into the first indoor heat exchanger 21A exchanges heat with the indoor air and condenses.

[0059] The refrigerant flowing out of the first indoor heat exchanger 21A flows through the first liquid refrigerant pipe 32A and the first outdoor unit liquid branch pipe 31A, and is reduced in pressure when passing through the first expansion valve 5A. The opening degree of the first expansion valve 5A is set so that the discharge temperature of the compressor 11 becomes the target discharge temperature. The refrigerant that has passed through the first expansion valve 5A flows through the outdoor unit liquid pipe 31 into the outdoor heat exchanger 13, where it exchanges heat with outside air and evaporates. The refrigerant that has flowed out of the outdoor heat exchanger 13 flows into the refrigerant pipe 16, flows through the four-way valve 12, refrigerant pipe 17, accumulator 14, and suction pipe 18, and is drawn into the compressor 11 and compressed again.

[0060] (Hot water supply operation) When the air conditioning apparatus 100 performs hot water supply operation in the second indoor unit 2B, the four-way valve 12 is switched to the state shown by the dashed lines in Fig. 1, i.e., state 1, in which port a and port d are connected and port b and port c are connected. Also, the first expansion valve 5A is fully opened, the first on-off valve 6A is closed, and the second on-off valve 6B is open. Adjustment of the opening of the second expansion valve 5B will be described later.

[0061] In this state, driving the compressor 11 circulates refrigerant through the refrigerant circuit 10, and driving the pump 53 circulates water through the water circuit 50. In this state, the outdoor heat exchanger 13 functions as an evaporator, and the second indoor heat exchanger 21B functions as a condenser. Here, closing the first on-off valve 6A prevents refrigerant from flowing into the first indoor heat exchanger 21A of the first indoor unit 2A, whose operation is stopped. Furthermore, fully opening the first expansion valve 5A causes the refrigerant remaining between the first indoor heat exchanger 21A and the first expansion valve 5A to flow out toward the outdoor unit gas pipe 41 by driving the compressor 11, thereby preventing refrigerant from accumulating between the first indoor heat exchanger 21A and the first expansion valve 5A.

[0062] The high-temperature, high-pressure refrigerant discharged from the compressor 11 flows into the four-way valve 12 through the discharge pipe 15, and then flows from the four-way valve 12 through the outdoor unit gas pipe 41, the second outdoor unit gas branch pipe 41B, the second on-off valve 6B in the fully open state, and the second gas refrigerant pipe 42B into the second indoor heat exchanger 21B. The refrigerant that flows into the second indoor heat exchanger 21B exchanges heat with water delivered by the pump 53 from the hot water storage tank 51 and condenses. The water delivered by the pump 53 from the hot water storage tank 51 is heated by heat exchange with the refrigerant in the second indoor heat exchanger 21B and then returns to the hot water storage tank 51. As a result, the hot water heated in the second indoor heat exchanger 21B is stored in the hot water storage tank 51.

[0063] Meanwhile, the refrigerant flowing out of the second indoor heat exchanger 21B flows through the second liquid refrigerant pipe 32B and the second outdoor unit liquid branch pipe 31B, and is reduced in pressure when passing through the second expansion valve 5B. The opening degree of the second expansion valve 5B is set so that the discharge temperature of the compressor 11 becomes the target discharge temperature. The refrigerant that has passed through the second expansion valve 5B flows through the outdoor unit liquid pipe 31 into the outdoor heat exchanger 13, where it exchanges heat with outside air and evaporates. The refrigerant that has flowed out of the outdoor heat exchanger 13 flows into the refrigerant pipe 16, flows through the four-way valve 12, refrigerant pipe 17, accumulator 14, and suction pipe 18, and is drawn into the compressor 11 and compressed again.

[0064] [Regarding the on-off valves] In this type of air conditioning apparatus, if a malfunction occurs in the on-off valves 6A, 6B during the heating cycle of heating operation or hot water supply operation, the following problems can occur. The malfunction here refers to the on-off valves 6A, 6B not operating according to the opening and closing operation instructions from the control unit 90, in other words, malfunction. Causes of the malfunction include, for example, mechanical factors such as the valve not closing normally due to foreign matter getting caught, and electrical factors such as a broken or short circuited solenoid coil. In the following explanation, a malfunction that requires repair is referred to as a failure.

[0065] For example, in FIG. 1 , if the second on-off valve 6B on the stopped indoor unit (second indoor unit 2B in the heating operation described above) is not closed during heating operation, the refrigerant flowing into the second indoor heat exchanger 21B condenses into liquid refrigerant there. This liquid refrigerant then flows through the fully open second expansion valve 5B into the outdoor heat exchanger 13. As a result, the temperature of the refrigerant drawn into the compressor 11 decreases, causing the temperature of the refrigerant discharged from the compressor 11 (discharge temperature) to decrease. During heating operation, the aperture of the first expansion valve 5A on the operating indoor unit (first indoor unit 2A) is adjusted to set the discharge temperature to a predetermined target temperature. Therefore, the aperture of the first expansion valve 5A is narrowed to set the lowered discharge temperature to the target temperature. As a result, more refrigerant flows into the stopped indoor unit (second indoor unit 2B) and condenses, resulting in a larger amount of liquid refrigerant flowing into the second outdoor heat exchanger 21B. If the amount of liquid refrigerant flowing into the outdoor heat exchanger 13 becomes large, the liquid refrigerant may not completely evaporate in the outdoor heat exchanger 13 and flow into the compressor 11, which is known as liquid backflow, and this may cause the compressor 11 to malfunction.

[0066] Furthermore, if the first on-off valve 6A on the operating indoor unit (first indoor unit 2A in the heating operation description above) does not open during heating operation, the second on-off valve 6B on the stopped indoor unit (second indoor unit 2B) is also closed, and the flow of refrigerant through the refrigerant circuit 10 is stopped by the on-off valves 6A, 6B. As a result, the pressure of the refrigerant discharged from the compressor 11 (discharge pressure) rises sharply, and control is executed to stop the compressor 11 to protect it from high pressure (high-pressure protection control). However, if the first on-off valve 6A on the operating indoor unit (first indoor unit 2A) does not open even after the compressor 11 is restarted, the high-pressure protection control will be executed again, causing the compressor 11 to start and stop frequently, thereby shortening its lifespan.

[0067] Therefore, in this embodiment, the control unit 90 detects the occurrence of a malfunction in the on-off valves 6A, 6B, and if a malfunction occurs, stops the compressor, thereby suppressing a decrease in the reliability of the compressor 11. The processing related to the above performed by the control unit 90 will be described in detail below.

[0068] [Details of the control unit] In this embodiment, the control unit 90 determines whether or not a malfunction has occurred in the first on-off valve 6A and the second on-off valve 6B based on the opening and closing operation instructions for the first on-off valve 6A and the second on-off valve 6B and the detection results of the first refrigerant sensor 84A and the second refrigerant sensor 84B.

[0069] Here, opening and closing operation instructions for the first opening and closing valve 6A and the second opening and closing valve 6B are set in advance according to the type of operation of the air conditioning apparatus 100. As described above, for example, during heating operation, the control unit 90 issues opening and closing operation instructions so that the first opening and closing valve 6A on the operating indoor unit (first indoor unit 2A) side is open, and the second opening and closing valve 6B on the stopped indoor unit (second indoor unit 2B) side is open. The control unit 90 acquires the detected temperatures (detected values) of the first refrigerant sensor 84A and the second refrigerant sensor 84B a predetermined time after the start of heating operation.

[0070] During heating operation, when the first on-off valve 6A and the second on-off valve 6B are in the open / closed state in accordance with the above-mentioned on-off operation instructions, high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows through the first gas pipe 4A (first outdoor unit gas branch pipe 41A), and no refrigerant flows through the second gas pipe 4B (second outdoor unit gas branch pipe 41B), so the detected temperatures of the first refrigerant sensor 84A and the second refrigerant sensor 84B will be different values. As a result, the open / closed state of each on-off valve 6A, 6B can be determined individually based on the on-off operation instructions for each on-off valve 6A, 6B and the detection results of each refrigerant sensor 84A, 84B.

[0071] In this embodiment, the open / closed state of each of the on-off valves 6A, 6B is determined based on the temperature difference between the temperatures detected by refrigerant sensors 84A, 84B located downstream of each of the on-off valves 6A, 6B in the direction of refrigerant flow during heating operation, and it is determined whether or not a malfunction has occurred in either of the on-off valves 6A, 6B.

[0072] For example, during heating operation, when the on-off valves 6A and 6B are operating normally in accordance with the opening and closing operation instructions of the control unit 90, the temperature detected by the first refrigerant sensor 84A (hereinafter referred to as TA) is higher than the temperature detected by the second refrigerant sensor 84B (hereinafter referred to as TB). If TA > TB, the control unit 90 determines that the first on-off valve 6A is open and the second on-off valve 6B is closed, and that both on-off valves 6A and 6B are normal, and continues heating operation. To enhance the reliability of the determination results, it is preferable to set a temperature difference between TA and TB that is greater than or equal to a predetermined value. This temperature difference is preferably a temperature difference that takes into account the temperature of the refrigerant flowing through the gas pipe and the outside air temperature, for example, 20°C or greater. In other words, during heating operation, the on-off state of the on-off valves 6A and 6B is determined to be normal when TA is greater than TB by 20°C or greater.

[0073] During hot water supply operation, the control unit 90 issues opening and closing instructions so that the second opening and closing valve 6B on the operating indoor unit (second indoor unit 2B) side is open and the first opening and closing valve A on the stopped indoor unit (first indoor unit 2A) side is open. The control unit 90 compares the detected temperatures of the first refrigerant sensor 84A and the second refrigerant sensor 84B after a predetermined time has elapsed since the start of hot water supply operation.

[0074] During hot water supply operation, when the first on-off valve 6A and the second on-off valve 6B are in the open / closed state according to the operational instructions, high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows through the second gas pipe 4B (second outdoor unit gas branch pipe 41B), while no refrigerant flows through the first gas pipe 4A (first outdoor unit gas branch pipe 41A). Therefore, the temperature TB detected by the second refrigerant sensor 84B is higher than the temperature TA detected by the first refrigerant sensor 84A. If TA < TB, the control unit 90 determines that the first on-off valve 6A is closed and the second on-off valve 6B is open. The control unit 90 then determines that both on-off valves 6A and 6B are normal and continues hot water supply operation. Because the refrigerant discharged from the compressor 11 is at a higher temperature during hot water supply operation than during heating operation, the on-off states of the on-off valves 6A and 6B may be determined to be normal if TB is, for example, 50°C or more higher than TA.

[0075] On the other hand, if the on-off valve on the stopped indoor unit does not close normally due to a foreign object or the like, the high-temperature, high-pressure gas refrigerant discharged from the compressor 11 will also flow into the gas pipe on the stopped indoor unit, and the temperature TB detected by the second refrigerant sensor 84B will no longer be the same as the temperature TA detected by the first refrigerant sensor 84A, or the temperature difference between TA and TB will no longer be greater than the predetermined value. In this case, the control unit 90 determines that a malfunction has occurred in the on-off valve on the stopped indoor unit, and stops the compressor 11.

[0076] Similarly, if the on-off valve on the driver's indoor unit does not open normally due to a foreign object getting caught in it, the refrigerant discharged from the compressor 11 will not flow not only through the gas pipe on the stopped indoor unit side but also through the gas pipe on the driver's indoor unit side, so the temperature TB detected by the second refrigerant sensor 84B will not be the same as the temperature TA detected by the first refrigerant sensor 84A, or the temperature difference between TA and TB will not be equal to or greater than the predetermined value. In this case, the control unit 90 will determine that a malfunction has occurred in the on-off valve on the driver's indoor unit side and will stop the compressor 11.

[0077] Since a malfunction of an on-off valve due to a foreign object or the like can be resolved by repeating the opening and closing operation of the valve, the control unit 90 issues an opening and closing operation command to the on-off valve determined to be malfunctioning again, and then restarts the compressor 11 (hereinafter, this process is also referred to as a retry process).As a result, if a temperature difference between TA and TB equal to or greater than the predetermined value is found, it is determined that the malfunction has been resolved, and if the temperature difference is not found, the retry process is executed again.

[0078] In addition, if a solenoid valve is used as the on-off valve, a malfunction due to a broken or short circuited solenoid coil may be considered. If the malfunction persists even after a predetermined number of consecutive retry attempts, the controller 90 determines that the on-off valve is faulty and stops the compressor. When the controller 90 determines that either the first on-off valve 6A or the second on-off valve 6B is faulty, it may generate a control signal indicating the occurrence of the malfunction. This control signal causes a display unit 23 (see FIG. 1 ) installed at any position in the air conditioning apparatus 100 to display an abnormality. The display unit 23 may be located on at least one of the first indoor unit 2A and the second indoor unit 2B. The display unit 23 may be a warning light installed on the front of the indoor unit housing or a display screen provided on the operation remote control. The display unit 23 may also be installed on the hot water storage tank 51 of the hot water supply apparatus 500.

[0079] FIG. 4 is a flowchart showing an example of a processing procedure for determining the operation of the on-off valves 6A and 6B, which is executed by the CPU 91 of the control unit 90 during heating operation or hot water supply operation.

[0080] When the air conditioning apparatus 100 starts operating, the control unit 90 determines whether the operating mode is heating operation or hot water supply operation (ST101). If the operating mode is cooling operation (No in ST101), the process ends. If the operating mode is heating operation or hot water supply operation (Yes in ST101), the control unit 90 issues a valve opening instruction to the operating indoor unit's on-off valve (on-off valve 6A during heating operation, on-off valve 6B during hot water supply operation) and a valve closing instruction to the stopped indoor unit's on-off valve (on-off valve 6B during heating operation, on-off valve 6A during hot water supply operation) (ST102), and determines whether the temperature difference ΔT between the detected temperature TA of the first refrigerant sensor 84A and the detected temperature TB of the second refrigerant sensor 84B is less than the threshold value α (ST103).

[0081] The temperature difference ΔT is the calculated value of TA-TB in the heating operation, and is the calculated value of TB-TA in the hot water supply operation. The threshold value α corresponds to the temperature difference equal to or greater than the predetermined value, for example, 50°C.

[0082] If the temperature difference ΔT is equal to or greater than the predetermined value α (No in ST103), the control unit 90 determines that both the first on-off valve 6A and the second on-off valve 6B are in a normal on-off state, and returns to ST101. On the other hand, if the temperature difference ΔT is less than the predetermined value α (Yes in ST103), the control unit 90 determines whether a predetermined time has elapsed since the compressor 11 was started and operation of the first indoor unit 2A or the second indoor unit 2B began (ST104). The predetermined time is not particularly limited as long as it is the time from the start of the compressor 11 until the temperatures detected by the first refrigerant sensor 84A and the second refrigerant sensor 84B stabilize, and is, for example, 10 to 15 minutes.

[0083] If the predetermined time has not elapsed (No in ST104), the control unit 90 determines that the temperature detected by the first refrigerant sensor 84A or the second refrigerant sensor 84B is not stable, and returns to ST102 to execute the above-described process. On the other hand, if the predetermined time has elapsed (Yes in ST104), the control unit 90 determines that a malfunction has occurred in either the first or second on-off valve 6A or 6B. For example, if the second on-off valve 6B does not close properly during heating operation, or if the first on-off valve 6A does not close properly during hot water supply operation, the temperature TA detected by the first refrigerant sensor 84A and the temperature TB detected by the second refrigerant sensor 84B are not equal to each other or do not have a temperature difference exceeding the predetermined value α. When it is determined that a malfunction has occurred in either the on-off valve 6A or 6B, the control unit 90 stops the compressor 11 and counts the number of times the compressor 11 has been stopped (ST105).

[0084] The count value of the number of times the compressor 11 has stopped is stored in the memory unit 92 of the control unit 90. The count value is reset when the operation of the air conditioning apparatus 100 is stopped by a user operation or when the operation mode is switched (for example, when the operation mode is switched from heating operation to hot water supply operation, or from hot water supply operation to heating operation or cooling operation).

[0085] The control unit 90 determines whether the number of times the compressor 11 has stopped because the temperature difference ΔT between the refrigerant sensors 84A, 84B is equal to or less than the predetermined value α has reached a predetermined number (N times) (ST106). The value of N is not particularly limited and may be, for example, 4. If the number of times the compressor 11 has stopped is less than four (No in ST106), the control unit 90 executes the above-mentioned retry process of issuing an opening / closing instruction to the on-off valves 6A, 6B again and then restarting the compressor 11 (ST107).

[0086] The retry process is executed after the compressor 11 is stopped and a time (e.g., three minutes) has elapsed until the refrigerant in the refrigerant circuit 10 is pressure-equalized. As a result, if the on-off valves 6A, 6B are not determined to be faulty, the valves can be opened and closed in accordance with the on-off operation command from the control unit 90. The on-off operation command for the on-off valves 6A, 6B preferably includes at least one open state and one closed state, so that a valve that has malfunctioned due to foreign matter or the like can be prompted to remove the foreign matter. After issuing the on-off operation command for the on-off valves 6A, 6B, the control unit 90 restarts the compressor 11.

[0087] After executing this retry process, the control unit 90 returns to ST101 and executes the above-described process again. At this time, if the malfunction occurring in either the first on-off valve 6A or the second on-off valve 6B has been resolved, the temperature difference ΔT between the refrigerant sensors 84A, 84B will be equal to or greater than the predetermined value α (No in ST103), and the heating operation or hot water supply operation can be continued. On the other hand, if the temperature difference ΔT is less than the predetermined value α (Yes in ST103), the compressor 11 is stopped again and the retry process is repeated to attempt to resolve the malfunction of the on-off valves 6A, 6B.

[0088] However, if the malfunction of either the first on-off valve 6A or the second on-off valve 6B remains unresolved even after three consecutive retry attempts, causing the compressor 11 to stop, and the number of such stops reaches a predetermined number (four), the control unit 90 determines that one of the on-off valves 6A, 6B is malfunctioning and stops operation of the air conditioning apparatus 100 without restarting the compressor 11 (ST108). This protects the compressor 11 from frequent on-off stops. Furthermore, the control unit 90 generates a control signal to display on the display unit 23 of each indoor unit 2A, 2B that a malfunction has occurred in the on-off valve 6A, 6B to notify the user of the abnormality (ST108).

[0089] The above process is performed at least once after the start of heating operation or hot water supply operation. However, the process may be performed periodically at predetermined intervals during heating operation or hot water supply operation. In this case, for example, a malfunction due to a foreign object becoming caught in an open valve can be detected early.

[0090] According to this embodiment, the first on-off valve 6A and the second on-off valve 6B are monitored for malfunctions during heating or hot water supply operation, and the compressor 11 is stopped if a malfunction is detected. This protects the compressor from so-called liquid backflow, which can occur when an increase in the amount of refrigerant flowing into the indoor heat exchanger of the stopped indoor unit occurs. The compressor can also be protected from the compressor's high-pressure protection shutdown process, which can frequently occur due to improper opening of the on-off valve on the operating indoor unit. This extends the life of the compressor 11, thereby improving the reliability of the air conditioner.

[0091] [Refrigerant Sensor] FIG. 5 is a side view showing a part of the refrigerant piping inside the heat source unit 1. As shown in FIG.

[0092] As described above, the first refrigerant sensor 84A is arranged between the first on-off valve 6A and the first gas pipe connection part 411 in the first outdoor unit gas branch pipe 41A, and the second refrigerant sensor 84B is arranged between the second on-off valve 6B and the second gas pipe connection part 412 in the second outdoor unit gas branch pipe 41B.

[0093] The refrigerant temperature sensors used as refrigerant sensors 84A, 84B should have as large a contact area as possible with the refrigerant piping in which they are placed to increase the accuracy of refrigerant temperature detection, and it is desirable that the refrigerant piping have a straight pipe section that is longer than the refrigerant temperature sensors. Meanwhile, due to the demand for smaller heat source units 1, the length of each refrigerant pipe tends to be shorter, and so it is necessary to devise a way to provide a straight pipe section in the outdoor unit gas branch pipes 41A, 41B in which refrigerant sensors 84A, 84B are placed that is long enough to accommodate the refrigerant sensors 84A, 84B, while preventing the heat source unit 1 from becoming larger.

[0094] 5 , the first outdoor unit gas branch pipe 41A, which connects the first on-off valve 6A and the first gas pipe connection 411, and the second outdoor unit gas branch pipe 41B, which connects the second on-off valve 6B and the second gas pipe connection 412, are each bent, for example, into a substantially L-shape to provide a straight pipe section 41s long enough to accommodate the first refrigerant sensor 84A and the second refrigerant sensor 84B. The refrigerant sensors 84A and 84B are, for example, cylindrical and are attached to the straight pipe section 41s so that their axes are parallel to the straight pipe section 41s. This ensures the detection accuracy of the refrigerant sensors 84A and 84B while miniaturizing the heat source unit 1.

[0095] Furthermore, by arranging the first refrigerant sensor 84A and the second refrigerant sensor 84B inside the heat source unit 1, these refrigerant sensors 84A, 84B are less susceptible to the environment outside the heat source unit 1, and it is possible to maintain stable refrigerant temperature detection accuracy. Furthermore, because the refrigerant sensors 84A, 84B can be installed in the outdoor unit gas branch pipes 41A, 41B inside the heat source unit 1 with their wiring connection to the control unit 90 completed, there is no need to separately install the refrigerant sensors 84A, 84B or connect them to the control unit 90 when installing the air conditioning apparatus 100, improving workability.

[0096] [Modifications] In the above embodiment, the first expansion valve 5A and the second expansion valve 5B are both arranged inside the heat source unit 1 (first outdoor unit liquid pipe 31A and second outdoor unit liquid pipe 31B), but this is not limited thereto and they may be arranged in the first liquid refrigerant pipe 32A and the second liquid refrigerant pipe 32B, respectively. Similarly, the first on-off valve 6A and the second on-off valve 6B may be arranged in the first gas refrigerant pipe 42A and the second gas refrigerant pipe 42B, respectively. The positions of the first refrigerant sensor 84A and the second refrigerant sensor 84B are not particularly limited as long as they are downstream of the first on-off valve 6A and the second on-off valve 6B in the refrigerant flow direction during the heating cycle, and they may be arranged in the first gas refrigerant pipe 42A and the second gas refrigerant pipe 42B, for example.

[0097] In the above embodiment, a malfunction of either the first on-off valve 6A or the second on-off valve 6B is detected using the difference (temperature difference) between the detection values ​​of the first refrigerant sensor 84A and the second refrigerant sensor 84B. However, instead, the presence or absence of a malfunction of each on-off valve 6A, 6B may be determined individually using each refrigerant sensor 84A, 84B. For example, when the first indoor unit 2A is performing heating operation, the control unit 90 opens the first on-off valve 6A and closes the second on-off valve 6B. In this case, if the first refrigerant sensor 84A detects a temperature corresponding to, for example, the temperature of the refrigerant discharged from the compressor 11 (discharge temperature), it can be determined that the first on-off valve 6A is normally open. If the second refrigerant sensor 84B detects a temperature corresponding to, for example, the outdoor temperature, it can be determined that the second on-off valve 6B is normally closed.

[0098] Second Embodiment Fig. 6 is a refrigerant circuit diagram showing an example of the configuration of an air conditioning apparatus 200 according to another embodiment of the present invention. Hereinafter, parts corresponding to those in Fig. 1 are given the same reference numerals, and detailed description thereof will be omitted.

[0099] In the first embodiment described above, the first on-off valve 6A and the second on-off valve 6B are normally open solenoid valves that are closed when energized, but in this embodiment, the first on-off valve 6A and the second on-off valve 6B are normally closed solenoid valves that are open when energized, which is different from the first embodiment. The present embodiment also differs from the first embodiment in that the first refrigerant sensor 84A and the second refrigerant sensor 84B are not provided.

[0100] In this embodiment, the first on-off valve 6A is arranged in the first outdoor unit gas pipe 41A, and the second on-off valve 6B is arranged in the second outdoor unit gas pipe 41B. As in the first embodiment, when the refrigerant circuit 10 is in the heating cycle, the control unit 90 issues opening and closing operation instructions so that the on-off valve on the operating indoor unit side (the first on-off valve 6A during heating operation and the second on-off valve 6B during hot water supply operation) is in an open state, and the on-off valve on the stopped indoor unit side (the second on-off valve 6B during heating operation and the first on-off valve 6A during hot water supply operation) is in a closed state.

[0101] Here, when the on-off valves 6A, 6B are normally closed solenoid valves that open when energized, if the on-off valve on the driver's indoor unit side does not open normally despite a valve open command (energization on) being issued from the control unit 90, the on-off valve on the stopped indoor unit side is closed, blocking the flow of refrigerant in the gas pipe 4. As a result, the pressure of the refrigerant discharged from the compressor 11 rises, the high-pressure protection operation of the compressor 11 is activated, and the compressor 11 stops. Furthermore, if the on-off valve on the driver's indoor unit side does not open even after the compressor 11 is restarted, the high-pressure protection control will be executed again, causing the compressor 11 to start and stop frequently, thereby shortening the life of the compressor 11.

[0102] Therefore, in this embodiment, a high-pressure sensor 71, which is a refrigerant pressure sensor located between the discharge side of the compressor 11 in the gas pipe 4 and the on-off valves 6A and 6B, is used as the refrigerant sensor, and the on-off state (presence or absence of a malfunction) of the on-off valves 6A and 6B is determined using the on-off operation instructions for the on-off valves 6A and 6B and the detection results of the high-pressure sensor 71.

[0103] FIG. 7 is a flowchart showing an example of a processing procedure for operation determination processing of the on-off valves 6A, 6B executed by the control unit 90 of the air conditioning apparatus 200 of this embodiment during the heating cycle (during heating operation or hot water supply operation).

[0104] When the air conditioning apparatus 200 starts operating, the control unit 90 determines whether the operation mode is heating operation or hot water supply operation (ST201). If the operation mode is cooling operation (No in ST201), the process ends. If the operation mode is heating operation or hot water supply operation (Yes in ST201), the control unit 90 issues a valve open instruction to the on-off valve on the operating indoor unit side (on-off valve 6A in heating operation, on-off valve 6B in hot water supply operation) and a valve close instruction to the on-off valve on the stopped indoor unit side (on-off valve 6B in heating operation, on-off valve 6A in hot water supply operation) (ST202), and determines whether the pressure P detected by the high-pressure sensor 71 is equal to or greater than the threshold value β (ST203).

[0105] The threshold value β is not particularly limited as long as it is a pressure at which a malfunction in which the on-off valve on the driver's indoor unit (the first on-off valve 6A during heating operation, and the second on-off valve 6B during hot water operation) does not open during the heating cycle can be detected, but it is preferable that the threshold value β be a pressure lower than the pressure at which high-pressure protection control of the compressor 11 is executed.

[0106] If the on-off valve on the operating indoor unit does not open due to a malfunction despite an operation command (energization ON) from the control unit 90 to that valve, the on-off valve on the stopped indoor unit (the second on-off valve 6B in heating operation and the first on-off valve 6A in hot water operation) remains closed, blocking the flow of refrigerant from the compressor 11 to the indoor heat exchangers 21A, 21B. As a result, when the detection value of the high-pressure sensor 71 reaches or exceeds the threshold value β (Yes in ST203), the control unit 90 determines that one of the on-off valves 6A, 6B is malfunctioning, stops the compressor 11, and counts the number of times the compressor 11 has stopped (ST204).

[0107] The control unit 90 determines whether the number of times the compressor 11 has stopped because the detected value P of the high-pressure sensor 71 is equal to or greater than the predetermined value β has reached a predetermined number (N times) (ST205). The value of N is not particularly limited and may be, for example, 4. If the number of times the compressor 11 has stopped is less than four (No in ST205), the control unit 90 executes a retry process in which the control unit 90 again issues an opening / closing instruction to each on-off valve 6A, 6B and then restarts the compressor 11 (ST206).

[0108] After executing this retry process, the control unit 90 returns to ST201 and executes the above-described process again. At this time, if the malfunction occurring in either the first on-off valve 6A or the second on-off valve 6B has been resolved, the detected value P of the high-pressure sensor 71 will be less than the predetermined value β (No in ST203), and the heating operation or hot water supply operation can be continued. On the other hand, if the detected value P is equal to or greater than the predetermined value β (Yes in ST203), the compressor 11 is stopped again and the retry process is repeated to attempt to resolve the malfunction of the on-off valves 6A, 6B.

[0109] However, if the malfunction of either the first on-off valve 6A or the second on-off valve 6B remains unresolved even after three consecutive retry attempts, causing the compressor 11 to stop, and the number of such stops reaches a predetermined number (four), the control unit 90 determines that one of the on-off valves 6A, 6B is malfunctioning and stops operation of the air conditioning apparatus 200 without restarting the compressor 11 (ST207). This protects the compressor 11 from frequent on-off stops. Furthermore, the control unit 90 generates a control signal to display on the display unit 23 of each indoor unit 2A, 2B that a malfunction has occurred in the on-off valve 6A, 6B to notify the user of the abnormality (ST207).

[0110] The above process is performed at least once after the start of heating operation or hot water supply operation. However, the present invention is not limited to this, and the above process may be performed periodically at predetermined intervals during heating operation or hot water supply operation. In this case, for example, a malfunction due to a foreign object becoming caught in an open valve can be detected early.

[0111] As described above, the present embodiment can also achieve the same effects as the first embodiment. According to the present embodiment, even if the on-off valves 6A, 6B are normally closed solenoid valves that are open when energized, it is possible to detect a malfunction of the on-off valves 6A, 6B based on the detection result of the high pressure sensor 71.

[0112] DESCRIPTION OF SYMBOLS 1...Heat source unit 2A...First indoor unit (use side unit) 2B...Second indoor unit (use side unit) 3A...First liquid pipe 3B...Second liquid pipe 4A...First gas pipe 4B...Second gas pipe 5A...First expansion valve 5B...Second expansion valve 6A...First on-off valve 6B...Second on-off valve 10...Refrigerant circuit 11...Compressor 12...Four-way valve 13...Outdoor heat exchanger (heat source side heat exchanger) 21A...First indoor heat exchanger (use side heat exchanger) 21B...Second indoor heat exchanger (use side heat exchanger) 23...Display unit 41A...First outdoor unit gas branch pipe 41B...Second outdoor unit gas branch pipe 71...High pressure sensor 84A...First refrigerant sensor 84B...Second refrigerant sensor 90...Control unit 100, 200...Air conditioning apparatus 411...first gas pipe connection part 412...second gas pipe connection part

Claims

1. An air conditioning apparatus comprising: a heat source unit having a compressor and a heat source side heat exchanger; a user side unit having a user side heat exchanger; a refrigerant circuit having a liquid pipe and a gas pipe connecting the heat source side heat exchanger and the user side heat exchanger, an expansion valve connected to the liquid pipe, and an on-off valve connected to the gas pipe; a refrigerant sensor disposed in the gas pipe and detecting the state of the refrigerant flowing through the gas pipe; and a control unit that controls each of the compressor, the expansion valve, and the on-off valve, wherein the control unit determines the on-off state of the on-off valve based on an on-off operation command for the on-off valve and the detection result of the refrigerant sensor.

2. An air conditioning apparatus according to claim 1, wherein the user-side units include a first indoor unit having a first indoor heat exchanger as the user-side heat exchanger, and a second indoor unit having a second indoor heat exchanger as the user-side heat exchanger; the gas pipes include a first gas pipe connecting one end of the heat source-side heat exchanger to the first indoor heat exchanger, and a second gas pipe connecting one end of the heat source-side heat exchanger to the second indoor heat exchanger; the on-off valves include a first on-off valve arranged in the first gas pipe, and a second on-off valve arranged in the second gas pipe; the refrigerant sensors include a first refrigerant sensor arranged in the first gas pipe between the first on-off valve and the first indoor heat exchanger, and a second refrigerant sensor arranged in the second gas pipe between the second on-off valve and the second indoor heat exchanger; an air conditioning apparatus that, when the refrigerant circuit is a heating cycle and the control unit is operating one of the first indoor unit and the second indoor unit and stopping the other, determines the open / close states of the first open / close valve and the second open / close valve using opening / closing operation instructions for the first open / close valve and the second open / close valve and the detection results of the first refrigerant sensor and the second refrigerant sensor.

3. An air conditioning apparatus as described in claim 2, wherein the liquid pipe includes a first liquid pipe connecting the other end of the heat source side heat exchanger to the first indoor heat exchanger, and a second liquid pipe connecting the other end of the heat source side heat exchanger to the second indoor heat exchanger, and the expansion valve includes a first expansion valve arranged in the first liquid pipe, and a second expansion valve arranged in the second liquid pipe.

4. An air conditioning apparatus as described in claim 3, wherein the heat source unit further has a first gas pipe connection portion, a second gas pipe connection portion, a first outdoor unit gas pipe forming part of the first gas pipe and connecting one end of the heat source side heat exchanger to the first gas pipe connection portion, and a second outdoor unit gas pipe forming part of the second gas pipe and connecting one end of the heat source side heat exchanger to the second gas pipe connection portion; the first on-off valve is arranged in the first outdoor unit gas pipe and the first refrigerant sensor is arranged in the first outdoor unit gas pipe between the first on-off valve and the first gas pipe connection portion, and the second on-off valve is arranged in the second outdoor unit gas pipe and the second refrigerant sensor is arranged in the second outdoor unit gas pipe between the second on-off valve and the second gas pipe connection portion.

5. An air conditioning apparatus as claimed in claim 3 or 4, wherein the control unit determines that a malfunction has occurred in either the first on-off valve or the second on-off valve when the difference between the detection value of the first refrigerant sensor and the detection value of the second refrigerant sensor is equal to or less than a predetermined value.

6. An air conditioning apparatus according to claim 5, wherein the first and second on-off valves are normally open solenoid valves that close when energized, and the control unit determines the open / closed state of the first and second on-off valves using the difference between the detection value of the first refrigerant sensor and the detection value of the second refrigerant sensor after a predetermined time has elapsed since operation of the first indoor unit or the second indoor unit began.

7. An air conditioning apparatus as described in claim 6, wherein, when the control unit determines that a malfunction has occurred in either the first on-off valve or the second on-off valve, it stops the compressor and then restarts it, and re-determines the open / closed state of the first on-off valve and the second on-off valve using the difference between the detection value of the first refrigerant sensor and the detection value of the second refrigerant sensor.

8. An air conditioning apparatus as described in claim 7, wherein when the control unit determines that a malfunction has occurred in either the first on-off valve or the second on-off valve a predetermined number of times in succession, it determines that a malfunction has occurred in that on-off valve and stops the compressor.

9. An air conditioning apparatus as described in claim 8, further comprising a display unit, wherein when the control unit determines that either the first on-off valve or the second on-off valve has failed, it generates a control signal that causes the display unit to display that the failure has occurred.

10. An air conditioning apparatus according to claim 9, wherein the display unit is disposed in at least one of the first indoor unit and the second indoor unit.

11. An air conditioning apparatus as claimed in claim 1, wherein the on-off valve is a normally closed solenoid valve that opens when energised, the refrigerant sensor is a refrigerant pressure sensor arranged in the gas pipe between the discharge side of the compressor and the on-off valve, and when the refrigerant circuit is in a heating cycle, the air conditioning apparatus determines the open / closed state of the on-off valve using an on-off operation command to the on-off valve and the detection result of the refrigerant pressure sensor.

12. A compressor, a heat source side heat exchanger, a first liquid pipe connection portion connected to the first indoor heat exchanger in a first indoor unit, a second liquid pipe connection portion connected to the second indoor heat exchanger in a second indoor unit, a first gas pipe connection portion connected to the first indoor heat exchanger, a second gas pipe connection portion connected to the second indoor heat exchanger, a first outdoor unit gas pipe connecting one end of the heat source side heat exchanger to the first gas pipe connection portion, a second outdoor unit gas pipe connecting one end of the heat source side heat exchanger to the second gas pipe connection portion, a first outdoor unit liquid pipe connecting the other end of the heat source side heat exchanger to the first liquid pipe connection portion, a second outdoor unit liquid pipe connecting the other end of the heat source side heat exchanger to the second liquid pipe connection portion, a first expansion valve arranged in the first outdoor unit liquid pipe, and a second expansion valve arranged in the second outdoor unit liquid pipe. a first refrigerant sensor disposed in the first outdoor unit gas pipe between the first on-off valve and the first gas pipe connection, and configured to detect a state of refrigerant flowing through the first outdoor unit gas pipe; a second refrigerant sensor disposed in the second outdoor unit gas pipe between the second on-off valve and the second gas pipe connection, and configured to detect a state of refrigerant flowing through the second outdoor unit gas pipe; and a control unit that controls the compressor, the first expansion valve, the second expansion valve, the first on-off valve, and the second on-off valve, respectively, wherein the control unit determines the open / close states of the first on-off valve and the second on-off valve based on open / close operation commands for the first on-off valve and the second on-off valve and detection results of the first refrigerant sensor and the second refrigerant sensor when operating one of the first indoor unit and the second indoor unit and stopping the other.

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