Air conditioner

Abstract

To suppress fixation of an opening / closing device and suppress a leakage amount of a refrigerant from an indoor unit in an air conditioner.SOLUTION: An air conditioner includes: an outdoor unit having a compressor; indoor units each having a utilization side heat exchanger; refrigerant piping connecting the outdoor unit and the indoor units; opening / closing devices disposed in the refrigerant piping; and a control section. The air conditioner also includes restriction devices each controlling a refrigerant flow rate between the opening / closing device and the utilization side heat exchanger. The control section executes fixation prevention operation for the opening / closing device in the case where a refrigerant is not leaked and the compressor is in operation and in the case where the compressor is in operation stop. In the case where the compressor is in operation and there is an indoor unit in operation stop, the control section performs opening control of the restriction device of the indoor unit that is in operation stop, and performs closing control of the restriction device of the indoor unit that is in operation to execute fixation prevention operation of the opening / closing device of the indoor unit that is in operation and performs opening / closing inspection of the opening / closing device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an air conditioning apparatus. [Background technology]

[0002] Conventionally, in air conditioners, a configuration is known in which an opening and closing device is provided in the refrigerant piping to suppress the amount of refrigerant leakage in the event of a refrigerant leakage (see, for example, Patent Document 1). In Patent Document 1, during cooling operation, the throttling device of the outdoor unit is controlled to make the refrigerant flowing in the liquid side piping a gas-liquid two-phase state, and when a refrigerant leakage is detected, the opening and closing devices upstream and downstream of the indoor heat exchanger are closed, thereby further reducing the amount of refrigerant leakage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 203606 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional air conditioners, the opening and closing device is not closed unless a refrigerant leak occurs. Therefore, there is a risk that the opening and closing device will become stuck if it is not closed for a long period of time. If the opening and closing device becomes stuck, the opening and closing device cannot be closed when a refrigerant leak occurs, and there is a risk that the amount of refrigerant leaking from the indoor unit will increase. The present invention has been made in consideration of the above-mentioned circumstances, and aims to prevent sticking of an opening and closing device in an air conditioning apparatus and to reduce the amount of refrigerant leakage from an indoor unit. [Means for solving the problem]

[0005] In order to solve the above problem, the present invention provides an air conditioning apparatus comprising an outdoor unit having a compressor, an indoor unit having a utilization side heat exchanger, refrigerant piping connecting the outdoor unit and the indoor unit, an opening / closing device arranged on the refrigerant piping, and a control unit, wherein the air conditioning apparatus further comprises a throttling device that controls the refrigerant flow rate between the opening / closing device and the utilization side heat exchanger, and the control unit performs a sticking prevention operation that opens and closes the opening / closing device when there is no refrigerant leakage and the compressor is operating or when the compressor is stopped, and when the compressor is operating and there is an indoor unit that is stopped, the control unit controls the throttling device of the indoor unit that is stopped to open and the throttling device of the indoor unit that is operating to close, thereby performing the sticking prevention operation for the opening / closing device of the indoor unit that is operating and also performs an opening / closing inspection of the opening / closing device. According to this, even when there is no refrigerant leakage, the opening and closing device is opened and closed, so that the sticking of the opening and closing device can be suppressed. [Effects of the Invention]

[0006] According to the present invention, since the sticking of the opening and closing device can be suppressed, it is easy to operate the opening and closing device appropriately when a refrigerant leak occurs, and the amount of refrigerant leaking from the indoor unit can be effectively suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing the configuration of an air conditioning apparatus according to a first embodiment. [Figure 2] Block diagram of a control unit of an air conditioning apparatus according to a first embodiment. [Figure 3] A flowchart showing the operation of determining whether to transition to sticking prevention in the air conditioning apparatus of the first embodiment [Figure 4] Flowchart showing the operation for preventing sticking of an air conditioning device [Figure 5] A flowchart showing the transition determination operation for detecting an abnormality in the air conditioning apparatus of the first embodiment. [Figure 6] Flowchart showing abnormality detection operation of an opening / closing device of an air conditioning device [Figure 7]Flowchart showing the remainder of Figure 6 [Figure 8] 1 is a flowchart showing the refrigerant leakage detection operation of the air conditioning apparatus of the first embodiment; [Figure 9] A flowchart showing the operation of determining whether to transition to sticking prevention in an air conditioning apparatus according to a second embodiment. [Figure 10] A flowchart showing the operation of determining whether to transition to sticking prevention in an air conditioning apparatus according to a third embodiment. [Figure 11] A flowchart showing the transition determination operation for abnormality detection in an air conditioning apparatus according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A first invention is an air conditioning apparatus comprising an outdoor unit having a compressor, an indoor unit having a utilization side heat exchanger, refrigerant piping connecting the outdoor unit and the indoor unit, an opening / closing device arranged on the refrigerant piping, and a control unit, and further comprising a throttling device that controls the refrigerant flow rate between the opening / closing device and the utilization side heat exchanger, and the control unit performs a freeze prevention operation that opens and closes the opening / closing device when there is no refrigerant leakage and the compressor is operating or when the compressor is stopped, and when the compressor is operating and there is an indoor unit that is stopped, the control unit controls the throttling device of the indoor unit that is stopped to open and the throttling device of the indoor unit that is operating to close, thereby performing the freeze prevention operation for the opening / closing device of the indoor unit that is operating and also performs an opening / closing inspection of the opening / closing device. This prevents the opening and closing device from not opening or closing for a long period of time, and prevents the opening and closing device from sticking. This makes it easier to operate the opening and closing device appropriately in the event of a refrigerant leak, and effectively reduces the amount of refrigerant leaking from the indoor unit.

[0009] In the second invention, when the control unit performs the sticking prevention operation, if the compressor is stopped, it performs the sticking prevention operation for the opening and closing devices of all of the indoor units, and if the compressor is operating, it performs the sticking prevention operation for the opening and closing devices of the indoor units that are stopped in order, thereby performing an opening and closing inspection of the opening and closing devices. This makes it possible to perform the sticking prevention operation and opening / closing inspection of the opening / closing device for all indoor units while suppressing the impact from the refrigerant flow. Furthermore, this allows, when the compressor is in operation, the opening and closing device sticking prevention operation and opening and closing inspection to be carried out in order starting from the indoor units that are not in operation.

[0010] An embodiment of the present invention will now be described with reference to the accompanying drawings. [1. First Embodiment] FIG. 1 is a diagram showing the configuration of an air conditioner 1 according to the first embodiment. The air conditioner 1 comprises an outdoor unit 20 and multiple indoor units 30a, 30b, and 30c. Each of the indoor units 30a, 30b, and 30c is connected in parallel to the outdoor unit 20 by a liquid side pipe 11 and a gas side pipe 12. The liquid side pipe 11 comprises liquid side pipes 13a, 13b, and 13c that branch off and are connected to each of the indoor units 30a, 30b, and 30c. The gas side pipe 12 comprises gas side pipes 14a, 14b, and 14c that branch off and are connected to each of the indoor units 30a, 30b, and 30c. The air conditioner 1 circulates refrigerant compressed by the outdoor unit 20 between the outdoor unit 20 and the indoor units 30a, 30b, and 30c, and conditions the conditioned space in which the indoor units 30a, 30b, and 30c are installed.

[0011] Because each of the indoor units 30a, 30b, and 30c is configured in the same way, in the following explanation, corresponding components of each of the indoor units 30a, 30b, and 30c are distinguished by being given the same numerical symbols and adding the suffixes a, b, and c. Also, when there is no particular need to distinguish between corresponding components, only the numerical symbols may be used and the suffixes a, b, and c may be omitted.

[0012] The outdoor unit 20 includes a compressor 201 that compresses the refrigerant, an outdoor heat exchanger 202 that exchanges heat with the refrigerant, an outdoor fan 203, an expansion valve 204, and a switching valve 205. The compressor 201 draws in the refrigerant from the suction pipe 208, compresses it, and discharges it. The outdoor heat exchanger 202 exchanges heat between the refrigerant and the outdoor air in the outdoor unit 20 .

[0013] The outdoor fan 203 sends air to the outdoor heat exchanger 202 . The expansion valve 204 reduces the pressure of the high-pressure refrigerant and causes it to expand. The expansion valve 204 is configured to have an adjustable opening. The opening of the expansion valve 204 is controlled by the control unit 100. The expansion valve 204 may be a valve that has an adjustable opening and can shut off the refrigerant. The switching valve 205 is configured by, for example, a four-way valve. The switching valve 205 switches the flow of the refrigerant discharged from the compressor 201 and the refrigerant returning to the compressor 201. The switching valve 205 switches the air conditioner 1 between a cooling operation mode and a heating operation mode.

[0014] The indoor unit 30 includes an indoor heat exchanger 301 , an indoor fan 302 , an indoor expansion valve 304 , a first temperature sensor 305 , a second temperature sensor 306 , and a refrigerant leakage sensor 307 . The indoor heat exchanger 301 exchanges heat between the indoor air and the refrigerant supplied from the outdoor unit 20 through the liquid side pipe 11 or the gas side pipe 12. The indoor heat exchanger 301 corresponds to an example of a utilization side heat exchanger. The indoor fan 302 sends air to the indoor heat exchanger 301 .

[0015] The indoor expansion valve 304 is an expansion valve arranged in the liquid side piping 11 between the expansion valve 204 and the indoor heat exchanger 301. In this embodiment, the indoor expansion valve 304 is arranged in the liquid side piping 13 connected to the indoor heat exchanger 301. The indoor expansion valve 304 has the same configuration as the expansion valve 204. The indoor expansion valve 304 corresponds to an example of a throttling device.

[0016] A first temperature sensor 305 is provided in the liquid side pipe 13 of the indoor heat exchanger 301. In this embodiment, the first temperature sensor 305 is provided at a connection portion where the liquid side pipe 13 is connected to the indoor heat exchanger 301. The first temperature sensor 305 detects the temperature of the refrigerant and inputs a detection signal to the control unit 100. A second temperature sensor 306 is provided in the gas side pipe 14 of the indoor heat exchanger 301. In this embodiment, the second temperature sensor 306 is provided at a connection portion where the gas side pipe 14 is connected to the indoor heat exchanger 301. The second temperature sensor 306 detects the temperature of the refrigerant and inputs a detection signal to the control unit 100.

[0017] A refrigerant leakage sensor 307 is disposed near the indoor heat exchanger 301. The refrigerant leakage sensor 307 detects the concentration of the refrigerant and inputs a detection signal to the control unit 100. When the concentration of the refrigerant is equal to or greater than a predetermined value, a refrigerant leak is detected.

[0018] On both sides of the indoor heat exchanger 301 of the indoor unit 30, a first opening and closing device 101 and a second opening and closing device 102 for adjusting the flow rate of refrigerant to the indoor unit 30 are provided.

[0019] The first opening and closing device 101 is provided on the liquid side piping 13 connected to the indoor heat exchanger 301. The first opening and closing device 101 of this embodiment is configured as an opening and closing valve such as an electric valve or a solenoid valve. The first opening and closing device 101 is switchable between an open state in which the refrigerant flows and a closed state in which the flow of the refrigerant is blocked. The first opening and closing device 101 is configured so that its opening and closing can be controlled by the control unit 100. Furthermore, the first opening and closing device 101 is configured to be in a closed state during a power outage. The first opening and closing device 101 may be a valve that can be set between an open state and a closed state, and the opening degree of the first opening and closing device 101 may be controlled by the control unit 100.

[0020] The second opening and closing device 102 is provided on the gas side piping 14 connected to the indoor heat exchanger 301. The second opening and closing device 102 has the same configuration as the first opening and closing device 101.

[0021] In the cooling operation mode of the air conditioning device 1, the refrigerant flows in the flow direction F1, passing through the compressor 201, the switching valve 205, the outdoor heat exchanger 202, the expansion valve 204, the indoor expansion valve 304, the indoor heat exchanger 301, and the switching valve 205 in that order, before returning from the switching valve 205 to the suction pipe 208.

[0022] In addition, in the heating operation mode of the air conditioning unit 1, the refrigerant flows in the flow direction F2, and flows in the order of compressor 201, switching valve 205, indoor heat exchanger 301, indoor expansion valve 304, expansion valve 204, outdoor heat exchanger 202, and switching valve 205, and then returns from switching valve 205 to suction pipe 208.

[0023] FIG. 2 is a block diagram of the control unit 100 of the air conditioning apparatus 1 according to the first embodiment. As shown in Figs. 1 and 2, the air conditioning apparatus 1 includes a control unit 100. An operation unit 100a, which is composed of a remote control, an operation panel, etc., is connected to the control unit 100 via a wired or wireless connection. The operation unit 100a is provided with a display unit 100b. The display unit 100b is configured to display the operation status of the operation unit 100a and the operating status of the air conditioning apparatus 1. The operation unit 100a corresponds to an example of an input unit. The display unit 100b corresponds to an example of a notification means.

[0024] The control unit 100 executes operation control of the compressor 201, control of the opening degree and opening / closing of the expansion valve 204 and the indoor expansion valve 304, control of flow path switching of the switching valve 205, and control of operation and stopping of the outdoor fan 203 and the indoor fan 302. The control unit 100 also executes control of opening and closing of the first opening / closing device 101 and the second opening / closing device 102.

[0025] The control unit 100 operates the expansion valve 204, the indoor expansion valve 304, and the switching valve 205 to switch between the cooling operation mode and the heating operation mode of the air conditioner 1. The control unit 100 also controls the operating frequency and operation / stop of the compressor 201, and controls the outdoor fan 203 and the indoor fan 302, in accordance with the target temperature set by operating the operation unit 100a, and conditions the space to be conditioned in accordance with the target temperature.

[0026] The control unit 100 executes the process of the sticking prevention operation. The control unit 100 executes the process of the operation of determining whether the air conditioning apparatus 1 should transition to sticking prevention in order to execute the process of the sticking prevention operation. Furthermore, the control unit 100 executes processing for the operation of detecting an abnormality in the opening and closing device. The control unit 100 executes processing for the operation of determining whether to transition to abnormality detection in the air conditioner 1 in order to execute processing for the operation of detecting an abnormality in the opening and closing device. Furthermore, the control unit 100 executes processing for the operation of detecting refrigerant leakage from the air conditioner 1.

[0027] Various types of refrigerants can be used in the air conditioner 1. In recent years, refrigerants such as hydrocarbons, ammonia, and R32 have been used in air conditioners as so-called alternative refrigerants. Some of these alternative refrigerants are mildly flammable and others are flammable. In the event of a leak of a mildly flammable or flammable refrigerant, it is necessary to suppress the amount of refrigerant leakage so that the refrigerant concentration in the conditioned space of the indoor unit 30 does not reach the lower flammability limit (LFL). In particular, it is desirable to suppress the amount of refrigerant leakage from indoor units 30 installed in or near the conditioned space.

[0028] Fig. 3 is a flowchart showing the transition determination operation for sticking prevention of the air conditioning apparatus 1 of the first embodiment. Fig. 4 is a flowchart showing the sticking prevention operation of the air conditioning apparatus 1. The operations in Figs. 3 and 4 are executed by the control unit 100 controlling each part of the air conditioning apparatus 1.

[0029] As shown in Fig. 3, when the control unit 100 starts processing the transition determination operation for sticking prevention, it starts measuring a first predetermined time (step ST11). The first predetermined time is a time for setting an interval for executing the sticking prevention operation. The first predetermined time allows the first opening and closing device 101 and the second opening and closing device 102 to be opened and closed at a necessary and sufficient frequency, and prevents excessive opening and closing that would damage the opening and closing devices 101 and 102. In this embodiment, as an example, the first predetermined time is set to one week. When the control unit 100 starts measuring the first predetermined time, it determines whether or not the first predetermined time has elapsed (step ST12).

[0030] When the control unit 100 determines that the first predetermined time has not elapsed (step ST12; NO), it executes the process of step ST12. When the control unit 100 determines that the first predetermined time has elapsed (step ST12; YES), it executes the sticking prevention operation shown in FIG. 4 (step ST13). After executing the sticking prevention operation, the control unit 100 returns to step ST11 and starts measuring the first predetermined time (step ST11). That is, the control unit 100 executes the sticking prevention operation every first predetermined time.

[0031] As shown in FIG. 4, when the control unit 100 starts the sticking prevention operation, it determines whether the compressor 201 is in operation (ON) (step ST21). If the compressor 201 is in operation (step ST21; YES), the control unit 100 determines whether or not the number of operating indoor units 30 is one (step ST22).

[0032] If the number of operating indoor units 30 is one (step ST22; YES), the control unit 100 fully opens the indoor expansion valve 304 of the indoor unit 30 that is not operating, as an example of open control (step ST23). In this embodiment, the indoor expansion valves 304 of all indoor units 30 that are not operating are fully opened. This allows refrigerant to flow through the indoor units 30 that are not operating. Because refrigerant can flow through the indoor units 30 that are not operating, even if the flow of refrigerant is blocked in the indoor units 30 that are operating, excessive pressure rise in the refrigerant circuit is suppressed. Here, instead of fully opening the indoor expansion valves 304 of all stopped indoor units 30, a configuration may be adopted in which only the indoor expansion valves 304 of some of the stopped indoor units 30 are fully opened. In this case, for example, the indoor units 30a and 30b on the outdoor unit 20 side may be fully opened.

[0033] The control unit 100 controls to close the indoor expansion valve 304 of the indoor unit 30 that is in operation (step ST24). The closing control in step ST24 controls the opening degree of the indoor expansion valve 304 so that the opening degree of the indoor expansion valve 304 is closer to the fully closed side than it is currently. This suppresses the flow rate of the refrigerant flowing inside the indoor unit 30 that is in operation, and suppresses the impact that the opening and closing devices 101, 102 receive from the flow of refrigerant when opening and closing.

[0034] The control unit 100 closes the first opening and closing device 101 corresponding to the indoor unit 30 that is in operation (step ST25). The control unit 100 sets the first opening and closing device 101 corresponding to the indoor unit 30 in operation to the open state (step ST26). The control unit 100 closes the second opening and closing devices 102 corresponding to the indoor units 30 that are in operation (step ST27). The control unit 100 opens the second opening and closing devices 102 corresponding to the indoor units 30 that are in operation (step ST28). Steps ST25 to ST28 open and close the first opening and closing device 101 and the second opening and closing device 102 of the indoor unit 30 that was in operation, thereby preventing the first opening and closing device 101 and the second opening and closing device 102 from sticking.

[0035] The control unit 100 controls the indoor expansion valve 304 of the indoor unit 30 that is in operation to open (step ST29). The opening control in step ST29 controls the opening degree of the indoor expansion valve 304 to the opening degree before the indoor expansion valve 304 was controlled to close in step ST24. This allows the refrigerant to flow at the same flow rate as when the indoor unit 30 is in operation. The control unit 100 fully closes the indoor expansion valve 304 of the indoor unit 30 that is not operating, which was fully opened in step ST23 (step ST30), thereby blocking the flow of refrigerant to the indoor unit 30 that is not operating.

[0036] The control unit 100 closes the first opening and closing device 101 corresponding to the indoor unit 30 that is not operating (step ST31). The control unit 100 opens the first opening and closing device 101 corresponding to the indoor unit 30 that is not operating (step ST32). The control unit 100 closes the second opening and closing device 102 corresponding to the indoor unit 30 that is not operating (step ST33). The control unit 100 opens the second opening and closing devices 102 corresponding to the indoor units 30 that are not operating (step ST34). Steps ST31 to ST34 open and close the first opening and closing device 101 and the second opening and closing device 102 corresponding to the indoor unit 30 that was out of operation, thereby preventing the first opening and closing device 101 and the second opening and closing device 102 from sticking. Then, the control unit 100 ends the sticking prevention operation when the number of operating indoor units 30 is one.

[0037] If the number of operating indoor units 30 is not one, i.e., if there are multiple operating indoor units 30 (step ST22; NO), the control unit 100 sets the operating indoor units 30 into "leading" and "lagging" groups (step ST41). At least one operating indoor unit 30 needs to be set into the "leading" and "lagging" groups. As long as at least one indoor unit 30 is set, the method for setting the "leading" and "lagging" groups can be arbitrary. In this embodiment, when the indoor unit 30a is operating, the indoor unit 30a is set as "leading," and the remaining operating indoor units 30b and 30c are set as "lagging." Furthermore, when the indoor unit 30a is not operating, the indoor unit 30b is set as "leading," and the indoor unit 30c is set as "lagging." The "leading" operating indoor unit 30 corresponds to an example of a first operating indoor unit 30. Furthermore, the "later" indoor unit 30 in operation corresponds to an example of a second indoor unit 30 in operation.

[0038] The control unit 100 controls to close the indoor expansion valve 304 of the "first" indoor unit 30 in operation (step ST42). The closing control in step ST42 is the same closing control as in step ST24. The control unit 100 closes the opening and closing devices 101, 102 corresponding to the "first" indoor unit 30 in operation (step ST43). The control unit 100 sets the opening and closing devices 101, 102 corresponding to the "first" indoor unit 30 in operation to the open state (step ST44). Steps ST43 to ST44 open and close the first opening and closing device 101 and the second opening and closing device 102 corresponding to the "first" operating indoor unit 30, thereby preventing sticking of the first opening and closing device 101 and the second opening and closing device 102. At this time, refrigerant can flow in the "following" operating indoor unit 30, so excessive pressure rise in the refrigerant circuit is suppressed. The control section 100 controls to open the indoor expansion valve 304 corresponding to the "first" indoor unit 30 in operation (step ST45). The opening control in step ST45 is the same as the opening control in step ST29.

[0039] The control unit 100 controls to close the indoor expansion valve 304 corresponding to the "later" indoor unit 30 in operation (step ST46). The closing control in step ST46 is the same as the closing control in step ST24. The control unit 100 closes the opening and closing devices 101, 102 corresponding to the "later" indoor units 30 in operation (step ST47). The control unit 100 sets the opening and closing devices 101, 102 corresponding to the "later" indoor units 30 in operation to the open state (step ST48). Steps ST47 to ST48 open and close the first opening and closing device 101 and the second opening and closing device 102 corresponding to the "following" operating indoor unit 30, thereby preventing sticking of the first opening and closing device 101 and the second opening and closing device 102. At this time, refrigerant can flow in the "leading" operating indoor unit 30, so excessive pressure rise in the refrigerant circuit is suppressed. The control unit 100 controls to open the indoor expansion valve 304 corresponding to the "later" indoor unit 30 in operation (step ST49). The opening control in step ST49 is the same as the opening control in step ST29.

[0040] The control unit 100 determines whether or not there is any indoor unit 30 that is not operating (step ST50). When the control unit 100 determines that there is no indoor unit 30 that is not operating (step ST50; YES), it ends the sticking prevention operation when there are multiple indoor units 30 that are operating.

[0041] If there is an indoor unit 30 that is out of operation (step ST50; NO), the control unit 100 executes the processing of steps ST31 to ST34 for the out-of-operation indoor unit 30. Then, the control unit 100 ends the sticking prevention operation when there are multiple indoor units 30 in operation.

[0042] When the control unit 100 determines that the compressor 201 is stopped (step ST21; NO), it closes the first opening and closing devices 101 corresponding to all the indoor units 30 (step ST51). The control unit 100 sets the first opening and closing devices 101 corresponding to all of the indoor units 30 to the open state (step ST52). The control unit 100 closes the second opening and closing devices 102 corresponding to all of the indoor units 30 (step ST53). The control unit 100 sets the second opening and closing devices 102 corresponding to all of the indoor units 30 to the open state (step ST54). Steps ST51 to ST54 open and close the first opening and closing device 101 and the second opening and closing device 102 corresponding to the indoor unit 30 that is not operating, thereby preventing sticking of the first opening and closing device 101 and the second opening and closing device 102. At this time, the compressor 201 is stopped and no refrigerant is flowing, so control of the indoor expansion valve 304 is omitted. Then, the control unit 100 ends the sticking prevention operation when the compressor 201 is stopped.

[0043] In the conventional configuration described in Patent Document 1, the opening and closing device is not closed unless a refrigerant leak occurs. Therefore, there is a risk that the opening and closing device will become stuck if it is not closed for a long period of time. Therefore, when a refrigerant leak actually occurs, the opening and closing device does not function properly, the refrigerant circuit cannot be shut off, and the amount of refrigerant leakage increases.

[0044] In contrast, in this embodiment, the opening and closing devices 101, 102 are opened and closed by the processing of steps ST25 to ST28, steps ST31 to ST34, steps ST43 to ST44, steps ST47 to ST48, and steps ST51 to ST54, even when there is no refrigerant leakage. As a result, the opening and closing devices 101, 102 move between the closed state (fully closed) and the open state (fully open), and sticking of the opening and closing devices can be suppressed. Therefore, when a refrigerant leakage occurs, it is easy to operate the opening and closing devices 101, 102 appropriately, and the amount of refrigerant leaking from the indoor unit 30 can be effectively suppressed.

[0045] In this embodiment, in steps ST25 to ST28 described above, the first opening and closing device 101 is opened and closed, and then the second opening and closing device 102 is opened and closed. However, instead of this, the first opening and closing device 101 may be opened and closed after the second opening and closing device 102 is opened and closed. Also, the first opening and closing device 101 and the second opening and closing device 102 may be opened and closed simultaneously. Similarly, in this embodiment, in the above-mentioned steps ST31 to ST34, the first opening and closing device 101 is opened and closed before the second opening and closing device 102 is opened and closed, but instead, the first opening and closing device 101 may be opened and closed after the second opening and closing device 102 is opened and closed, or the first opening and closing device 101 and the second opening and closing device 102 may be opened and closed simultaneously.

[0046] Furthermore, in this embodiment, in steps ST31 to ST34 described above, the opening and closing devices 101, 102 of all of the stopped indoor units 30 are opened and closed simultaneously. However, instead of this, steps ST31 to ST34 may be executed for each stopped indoor unit 30, and the opening and closing devices 101, 102 may be opened and closed in the order of the stopped indoor units 30, thereby opening and closing all of the opening and closing devices 101, 102 of the stopped indoor units 30.

[0047] As described above, the air conditioning apparatus 1 of this embodiment comprises the outdoor unit 20 having the compressor 201, the indoor unit 30 having the indoor heat exchanger 301, the liquid side pipes 11, 13 and the gas side pipes 12, 14 that connect the outdoor unit 20 and the indoor unit 30, the opening and closing devices 101, 102 arranged on the liquid side pipe 13 and the gas side pipe 14, and the control unit 100. In this air conditioning apparatus 1, the control unit 100 performs a sticking prevention operation that opens and closes the opening and closing devices 101, 102 when there is no refrigerant leakage. This prevents the opening and closing devices 101, 102 from not opening or closing for a long period of time, and suppresses sticking of the opening and closing devices 101, 102. Therefore, when a refrigerant leak occurs, it becomes easier to operate the opening and closing devices 101, 102 appropriately, and the amount of refrigerant leaking from the indoor unit 30 can be effectively suppressed.

[0048] In this embodiment, the refrigerant piping includes liquid side piping 11 and 13 and gas side piping 12 and 14. The opening and closing device includes a first opening and closing device 101 that opens and closes the liquid side piping 13 connected to the indoor unit 30, and a second opening and closing device 102 that opens and closes the gas side piping 14 connected to the indoor unit 30. This makes it possible to open and close the liquid side pipe 13 and the gas side pipe 14 connected to the indoor unit 30, and in the event of a refrigerant leak, the amount of refrigerant leaking from the indoor unit 30 can be effectively suppressed.

[0049] In addition, in this embodiment, the control unit 100 executes a sticking prevention operation in which the first opening and closing device 101 and the second opening and closing device 102 are operated to open and close. This prevents the first opening and closing device 101 and the second opening and closing device 102 from not opening and closing for a long period of time, and suppresses sticking of the first opening and closing device 101 and the second opening and closing device 102. Therefore, in the event of a refrigerant leak, the liquid side piping 11 and the gas side piping 12 connected to the indoor unit 30 can be opened and closed appropriately.

[0050] In this embodiment, the liquid side piping 11 is provided with an indoor expansion valve 304 that controls the flow rate of refrigerant between the first opening and closing device 101 and the indoor heat exchanger 301. This allows the flow rate of the refrigerant flowing through the indoor heat exchanger 301 to be controlled by the indoor expansion valve 304.

[0051] Furthermore, in this embodiment, there are multiple indoor units 30a, 30b, 30c arranged in parallel, each of which is provided with a first opening / closing device 101a, 101b, 101c and a second opening / closing device 102a, 102b, 102c, and each of which is provided with an indoor expansion valve 304a, 304b, 304c. This makes it possible to effectively reduce the amount of refrigerant leaking from each of the indoor units 30a, 30b, 30c in an air conditioner 1 equipped with a plurality of indoor units 30a, 30b, 30c arranged in parallel.

[0052] Furthermore, in this embodiment, when the sticking prevention operation is executed, the control unit 100 executes the sticking prevention operation for the opening and closing devices 101, 102 of all the indoor units 30 if the compressor 201 is stopped. As a result, for all of the indoor units 30, the sticking prevention operation of the opening and closing devices 101, 102 can be executed while suppressing the impact from the flow of the refrigerant.

[0053] Furthermore, in this embodiment, when the control unit 100 executes the sticking prevention operation, if the compressor 201 is in operation and there is an indoor unit 30 that is not in operation, it controls the indoor expansion valve 304 of the indoor unit 30 that is not in operation to open, and controls the indoor expansion valve 304 of the indoor unit 30 that is in operation to close, thereby executing the sticking prevention operation for the opening and closing devices 101, 102 of the indoor units 30 that are in operation. This makes it easier to increase the refrigerant flow rate in indoor units 30 that are not operating, and easier to decrease the refrigerant flow rate in indoor units 30 that are operating. For this reason, the opening and closing devices 101, 102 corresponding to indoor units 30 that are operating can be opened and closed in a state where they are less likely to be shocked by the refrigerant flow. In addition, because the refrigerant can be circulated using indoor units 30 that are not operating, excessive pressure rise in the refrigerant circuit can be suppressed even when the opening and closing devices 101, 102 are opened and closed.

[0054] Furthermore, in this embodiment, when the compressor 201 is in operation and there are multiple indoor units 30 in operation, the control unit 100 closes the indoor expansion valve 304 of the "leading" indoor unit 30 in operation, and performs sticking prevention operation for the opening and closing devices 101, 102 of the "leading" indoor unit 30 in operation. Then, after that, it closes the indoor expansion valve 304 of the "lagging" indoor unit 30 in operation, and performs sticking prevention operation for the opening and closing devices 101, 102 of the "lagging" indoor unit 30 in operation. As a result, when performing the sticking prevention operation, if the compressor 201 is in operation and there are multiple indoor units 30 in operation, the sticking prevention operation is performed separately for the "leading" operating indoor unit 30 and the "lagging" operating indoor unit 30. Therefore, when performing the sticking prevention operation for the opening and closing devices 101, 102 of one of the "leading" and "lagging" operating indoor units 30, the other of the "leading" and "lagging" operating indoor units 30 can be used to circulate the refrigerant, thereby suppressing excessive pressure rise in the refrigerant circuit.

[0055] Furthermore, in this embodiment, when the control unit 100 executes the sticking prevention operation, it executes the sticking prevention operation for the opening and closing devices 101, 102 of the indoor units 30 that are not operating. As a result, when the compressor 201 is in operation, the sticking prevention operation can be performed on the opening and closing devices 101, 102 of the indoor units that are not in operation.

[0056] In this embodiment, the control unit 100 executes the sticking prevention operation again after a first predetermined time has elapsed since the sticking prevention operation was executed. This allows the sticking prevention operation to be performed every first predetermined time, and the sticking prevention operation to be performed with a necessary and sufficient frequency.

[0057] Fig. 5 is a flowchart showing the transition determination operation for abnormality detection of the air conditioner 1 of the first embodiment. Fig. 6 is a flowchart showing the abnormality detection operation of the opening and closing device of the air conditioner 1. Fig. 7 is a flowchart showing the rest of Fig. 6. The operations in Figs. 5 to 7 are executed by the control unit 100 controlling each part of the air conditioner 1.

[0058] As shown in FIG. 5, when the control unit 100 starts processing the transition determination operation for anomaly detection, it starts measuring a second predetermined time (step ST101). The second predetermined time is the shortest time interval for executing the anomaly detection operation. This makes it possible to prevent excessive execution of the anomaly detection operation for the switching device. In other words, it is possible to prevent excessive opening and closing of the first switching device 101 and the second switching device 102, which would cause damage to the switching devices 101 and 102. In this embodiment, the second predetermined time is set to one month, as an example.

[0059] The control unit 100 determines whether or not there is an instruction to control the decrease in the operating frequency of the compressor 201 (step ST102). When there is no instruction to control the decrease in the operating frequency of the compressor 201 (step ST102; NO), the control unit 100 executes the process of step ST102. When there is an instruction to control the operation frequency of the compressor 201 to decrease (step ST102; YES), the control unit 100 determines whether the operation frequency of the compressor 201 is equal to or lower than a predetermined value (step ST103). The predetermined value in step ST103 is set to an operation frequency at which the refrigerant flow rate is small and the opening and closing devices 101 and 102 are less likely to be shocked by the refrigerant flow when the opening and closing devices 101 and 102 are opened and closed.

[0060] When the control unit 100 determines that the operation frequency of the compressor 201 is not equal to or less than the predetermined value (step ST103; NO), the control unit 100 executes the process of step ST102. When the control unit 100 determines that the operation frequency of the compressor 201 is equal to or lower than the predetermined value (step ST103; YES), the control unit 100 determines whether or not the operation frequency is not 0 (step ST103). If the control unit 100 determines that the operating frequency of the compressor 201 is 0 (step ST104; NO), it stops the operation of the air conditioner 1 (step ST107) and executes the processing of step ST102.

[0061] When the control unit 100 determines that the operation frequency of the compressor 201 is not 0 (step ST104; YES), the control unit 100 determines whether or not the second predetermined time has elapsed (step ST105). In this way, it determines whether or not the second predetermined time has elapsed while the flow rate of the refrigerant is low. When the control section 100 determines that the second predetermined time has not elapsed (step ST105; NO), it executes the process of step ST102. When the control unit 100 determines that the second predetermined time has elapsed (step ST105; YES), it executes the operation of detecting an abnormality in the switching device shown in FIGS. 6 and 7 (step ST106). When the control unit 100 completes the operation of detecting an abnormality in the switching device, the control unit 100 returns to step ST101 and executes the processing of step ST101.

[0062] 6 and 7, the abnormality detection operation of the opening and closing device is executed for each of the indoor units 30a, 30b, and 30c. In this embodiment, the flowcharts of the abnormality detection operation of the opening and closing device shown in Fig. 6 and Fig. 7 are repeated in the order of the indoor unit 30a, the indoor unit 30b, and the indoor unit 30c. The abnormality detection operation of the opening and closing device corresponds to an example of abnormality determination control of the opening and closing device. 6, when the control unit 100 starts processing of an abnormality detection operation of a switching device, it determines whether or not the operation mode is cooling (step ST110). As a result, it determines the flow directions F1 and F2 of the refrigerant, and determines whether the first switching device 101 or the second switching device 102 is located upstream in the flow direction of the refrigerant.

[0063] When the control unit 100 determines that the operation mode is the cooling operation mode (step ST110; YES), it closes and throttles the indoor expansion valve 304 (step ST111). By throttling the indoor expansion valve 304, the refrigerant flow rate is reduced, and then the downstream second opening and closing device 102 is closed, thereby suppressing the impact on the second opening and closing device 102 when it is closed. The control unit 100 opens the first opening / closing device 101 corresponding to the upstream side and closes the second opening / closing device 102 corresponding to the downstream side (step ST112). As a result, when the second opening / closing device 102 functions normally, the second opening / closing device 102 is closed, and the refrigerant is blocked. As a result, the refrigerant stagnates in the indoor heat exchanger 301, and heat exchange does not occur in the indoor heat exchanger 301. This reduces the temperature difference between the refrigerant in the liquid side piping 13 upstream of the indoor heat exchanger 301 and the refrigerant in the gas side piping 14 downstream of the indoor heat exchanger 301.

[0064] The control unit 100 fully opens the indoor expansion valve 304 (step ST113). This makes it easier for the refrigerant to flow through the indoor heat exchanger 301 when an abnormality occurs in the second opening and closing device 102. The control unit 100 determines whether or not a third predetermined time has elapsed (step ST114). The third predetermined time in step ST114 is set to a time during which the refrigerant remaining in the indoor heat exchanger 301 stops exchanging heat with the indoor air. In this embodiment, four minutes is set as an example of the third predetermined time.

[0065] The control unit 100 determines whether the refrigerant temperatures in the liquid side pipe 13 and the gas side pipe 14 of the indoor heat exchanger 301 are equal to or lower than predetermined values (step ST115). In this embodiment, the control unit 100 calculates the difference between the temperature detected by the first temperature sensor 305 provided in the liquid side pipe 13 and the temperature detected by the second temperature sensor 306 provided in the gas side pipe 14. Then, it determines whether the difference between the detected temperatures is equal to or lower than a small predetermined value. Here, when the second opening and closing device 102 operates normally, the flow of refrigerant is blocked and the refrigerant stagnates in the indoor heat exchanger 301. As a result, heat exchange between the refrigerant and the indoor air does not occur in the indoor heat exchanger 301, and the temperature difference of the refrigerant between the liquid side pipe 13 and the gas side pipe 14 becomes small. On the other hand, when the second opening and closing device 102 is abnormal, the refrigerant continues to flow through the indoor heat exchanger 301, and heat exchange between the refrigerant and the indoor air continues in the indoor heat exchanger 301. As a result, a temperature difference of the refrigerant occurs between the liquid side pipe 13 and the gas side pipe 14. Therefore, in step ST115, in order to determine whether or not there is an abnormality in the second opening and closing device 102, it is determined whether or not the refrigerant temperature in the liquid side pipe 11 and the refrigerant temperature in the gas side pipe 12 of the indoor heat exchanger 301 are equal to or lower than a predetermined value.

[0066] If the control unit 100 determines that the refrigerant temperature in the liquid side piping 13 and the refrigerant temperature in the gas side piping 14 of the indoor heat exchanger 301 are below a predetermined value (step ST115; YES), it closes the first opening / closing device 101 corresponding to the upstream side and opens the second opening / closing device 102 corresponding to the downstream side (step ST116). The control unit 100 determines whether or not the third predetermined time has elapsed (step ST117). Step ST117 is the same as step ST114. The control unit 100 determines whether the refrigerant temperature in the liquid side pipe 13 and the refrigerant temperature in the gas side pipe 14 of the indoor heat exchanger 301 are equal to or lower than a predetermined value (step ST118). Step ST118 is the same as step ST115.

[0067] When the control unit 100 determines that the refrigerant temperature in the liquid side pipe 13 and the refrigerant temperature in the gas side pipe 14 of the indoor heat exchanger 301 are equal to or lower than a predetermined value (step ST118; YES), it opens the first opening and closing device 101 (step ST119). This returns the first opening and closing device 101 to its original state. Then, the control unit 100 ends the operation of detecting an abnormality in the switching device.

[0068] When the control unit 100 determines that the refrigerant temperature in the liquid side pipe 13 of the indoor heat exchanger 301 and the refrigerant temperature in the gas side pipe 14 are not equal to or lower than a predetermined value (step ST115; NO), it determines that there is an abnormality in the second opening and closing device 102 and notifies the abnormality of the second opening and closing device 102 (step ST122). As a means for notifying the abnormality of the second opening and closing device 102, it is possible to configure it so that it displays on the operation screen 100b that there is an abnormality in the second opening and closing device 102, or that it controls a sound source, which is an example of a notifying means (not shown), to sound an alarm. The control unit 100 fully closes the indoor expansion valve 304 (step ST121), thereby blocking the flow of refrigerant. Then, the control unit 100 ends the operation of detecting an abnormality in the switching device.

[0069] If the control unit 100 determines that the refrigerant temperature in the liquid side piping 13 and the refrigerant temperature in the gas side piping 14 of the indoor heat exchanger 301 are not below a predetermined value (step ST118; NO), it determines that there is an abnormality in the first opening and closing device 101 and notifies the abnormality in the first opening and closing device 101 (step ST120). The control unit 100 fully closes the indoor expansion valve 304 (step ST121), and ends the operation of detecting an abnormality in the opening and closing device.

[0070] If the operation mode is not the cooling mode, that is, if the operation mode is the heating mode (step ST110; NO), the control unit 100 closes and throttles the indoor expansion valve 304 (step ST130 in FIG. 7). Throttle the indoor expansion valve 304 to reduce the refrigerant flow rate. The control unit 100 opens the second opening / closing device 102 corresponding to the upstream side, and closes the first opening / closing device 101 corresponding to the downstream side (step ST131). Steps ST131 to ST141 shown in FIG. 7 are the same as steps ST112 to ST121 except that the upstream opening / closing device and the downstream opening / closing device are reversed from the opening / closing devices in steps ST112 to ST121 shown in FIG. 6, and therefore detailed explanations will be omitted.

[0071] Here, in the conventional configuration described in Patent Document 1, the opening and closing device is not closed unless a refrigerant leak occurs, which has the problem that the opening and closing device may become stuck, reducing the reliability of the opening and closing device.

[0072] In contrast to this, in this embodiment, by the processing of steps ST112 to ST115, steps ST116 to ST118, steps ST131 to ST134, and steps ST135 to ST137, it is determined whether the refrigerant is normally shut off when the opening and closing devices 101 and 102 are in the closed state. Therefore, if it is determined that the opening and closing devices 101 and 102 are abnormal, the opening and closing devices 101 and 102 can be repaired or replaced, thereby improving the reliability of the opening and closing devices 101 and 102.

[0073] As described above, the air conditioner 1 of this embodiment includes the outdoor unit 20 having the compressor 201, the indoor unit 30 having the indoor heat exchanger 301, the liquid side pipes 11, 13 and the gas side pipes 12, 14 connecting the outdoor unit 20 and the indoor unit 30, the first opening and closing device 101 that opens and closes the liquid side pipe 13 connected to the indoor unit 30, the second opening and closing device 102 that opens and closes the gas side pipe 13 connected to the indoor unit 30, the indoor expansion valve 304 that is provided between the first opening and closing device 101 and the indoor heat exchanger 301 and controls the refrigerant flow rate, and the control unit 100. In this air conditioner 1, the control unit 100 closes at least one of the first opening and closing device 101 and the second opening and closing device 102 while keeping the indoor expansion valve 304 open, and performs an abnormality detection operation to determine whether the one of the first opening and closing device 101 and the second opening and closing device 102 that is controlled to be closed is in an abnormal state. As a result, whether the first opening and closing device 101 and the second opening and closing device 102 are in an abnormal state can be determined depending on whether the refrigerant flowing through the indoor unit 30 is blocked by the opening and closing devices 101, 102 that have been controlled to close.

[0074] In this embodiment, the air conditioning apparatus 1 is equipped with a first temperature sensor 305 that is arranged in the liquid side piping 13 between the first opening and closing device 101 and the indoor heat exchanger 301 and detects the refrigerant temperature, and a second temperature sensor 306 that is arranged in the gas side piping 14 between the second opening and closing device 102 and the indoor heat exchanger 301 and detects the refrigerant temperature. In an abnormality detection operation, the control unit 100 of the air conditioning apparatus 1 controls one of the first opening and closing device 101 and the second opening and closing device 102 to open and controls the other opening and closing device 102 and 101 to close, and determines that the other opening and closing device 102 and 101 is in an abnormal state if the difference value between the temperatures detected by the first temperature sensor 305 and the second temperature sensor 306 is higher than a predetermined temperature. This makes it possible to detect the refrigerant temperature between the first opening and closing device 101 and the indoor heat exchanger 301, and the refrigerant temperature between the second opening and closing device 102 and the indoor heat exchanger 301. Therefore, it is possible to determine whether the refrigerant is blocked or not based on the temperature difference between the liquid side and the gas side of the indoor heat exchanger 301, and to determine whether the opening and closing devices 101 and 102 are in an abnormal state.

[0075] In addition, in this embodiment, during abnormality detection operation, the control unit 100 throttles the indoor expansion valve 304, controls the opening and closing devices 101, 102 that are upstream of the first opening and closing device 101 and the second opening and closing device 102 in the direction of refrigerant flow to open, and controls the opening and closing devices 102, 101 that are downstream to close, and determines whether the opening and closing devices 102, 101 on the downstream side are in an abnormal state. As a result, the indoor expansion valve 304 closes the opening and closing devices 102, 101 downstream in the refrigerant flow direction when the refrigerant flow rate to the opening and closing devices 102, 101 downstream in the refrigerant flow direction is reduced, thereby reducing the impact that the opening and closing devices 102, 101 receive from the refrigerant.

[0076] In addition, in this embodiment, in the abnormality detection operation, the control unit 100 determines whether the downstream opening and closing devices 102, 101 are in an abnormal state, and then controls the downstream opening and closing devices 102, 101 to open and controls the upstream opening and closing devices 101, 102 to close, thereby determining whether the upstream opening and closing devices 101, 102 are in an abnormal state. This also makes it possible to determine whether the opening and closing devices 102 and 101 located upstream in the flow direction of the refrigerant are abnormal.

[0077] Furthermore, in this embodiment, when the control unit 100 determines that the opening and closing devices 101 and 102 are in an abnormal state in the abnormality detection operation, it notifies the user that the opening and closing devices 101 and 102 are in an abnormal state. This makes it easier to recognize that the opening and closing devices 101 and 102 are in an abnormal state.

[0078] Furthermore, in this embodiment, the control unit 100 controls the indoor expansion valve 304 to close when it is determined in the abnormality detection operation that at least one of the first opening and closing device 101 and the second opening and closing device 102 is in an abnormal state. As a result, when the opening and closing devices 101 and 102 are in an abnormal state, the indoor expansion valve 304 can be controlled to close and the flow of the refrigerant can be regulated.

[0079] Furthermore, in this embodiment, if the operating frequency of the compressor 201 is equal to or lower than a predetermined value, and a second predetermined time has elapsed since the abnormality detection operation was performed, the control unit 100 performs the abnormality detection operation again. As a result, when the impact from the flow of the refrigerant is small, the opening and closing devices 101 and 102 can be opened and closed to perform the abnormality detection operation. Also, excessive execution of the abnormality detection operation can be suppressed.

[0080] 8 is a flowchart showing the refrigerant leakage detection operation of the air conditioner 1 of the first embodiment. The operation of FIG. 8 is executed by the control unit 100 controlling each part of the air conditioner 1. As shown in FIG. 8, when the control unit 100 starts the processing of the refrigerant leakage detection operation, it determines whether or not a refrigerant leakage has been detected based on the detection result of the refrigerant leakage sensor 307 (step ST201).

[0081] When the control unit 100 does not detect a refrigerant leak (step ST201; NO), the control unit 100 executes the process of step ST201. When the control unit 100 detects a refrigerant leak (step ST201; YES), it continues to operate the indoor fan 302 (step ST202). As a result, the refrigerant leaked into the room is transported by the air blown by the indoor fan 302, and the refrigerant leaked into the room is easily diluted.

[0082] The control unit 100 controls the operating frequency of the compressor 201 to decrease (step ST203). The control to decrease the operating frequency is performed, for example, as follows: The operating frequency of the compressor 201 before detection is controlled to a value obtained by multiplying the operating frequency by the ratio of the operating capacity of the indoor unit 30 in which a leak was detected to the operating capacity of all the indoor units 30. Specifically, for example, if the operating frequency before detection was 60 Hz, the operating capacity of the indoor unit 30 in which a leak was detected was 5 HP (horsepower), and the operating capacity of all the indoor units 30 was 15 HP, the operating frequency is controlled to decrease so that 60 Hz × (5 HP / 15 HP) = 20 Hz.

[0083] The control unit 100 fully closes the indoor expansion valve 304 in the indoor unit 30 in which leakage has been detected (step ST204), thereby regulating the flow of refrigerant. The control unit 100 closes the first opening and closing device 101 and the second opening and closing device 102 corresponding to the indoor unit 30 in which leakage has been detected (step ST205). The control unit 100 determines whether or not the first opening and closing devices 101 and the second opening and closing devices 102 corresponding to the indoor units 30 in which no leakage has been detected are in the open state (step ST206).

[0084] If the first opening / closing device 101 and the second opening / closing device 102 corresponding to the indoor unit 30 in which no leakage has been detected are in the open state (step ST206; YES), the control unit 100 continues operation (step ST207) and terminates the processing of the refrigerant leakage detection operation. If the first opening / closing device 101 and the second opening / closing device 102 corresponding to the indoor unit 30 in which leakage has not been detected are not in the open state (step ST206; NO), the control unit 100 stops operation (step ST208) and terminates the processing of the refrigerant leakage detection operation.

[0085] In the conventional configuration described in Patent Document 1, the opening and closing device is closed when a refrigerant leak occurs. However, simply closing the opening and closing device when a refrigerant leak occurs can cause the impact of the refrigerant flowing through the refrigerant circuit to be transmitted to the closed opening and closing device, potentially damaging the opening and closing device. Therefore, the conventional configuration poses a problem of reduced operational reliability of the opening and closing device.

[0086] In contrast to this, in this embodiment, the drive frequency is reduced to reduce the flow rate of the refrigerant in step ST203, and further the indoor expansion valve 304 is closed to regulate the flow of the refrigerant in step ST204, and then the first opening and closing device 101 and the second opening and closing device 102 are closed in step ST205. This prevents the impact of the refrigerant flowing in the refrigerant circuit from being transmitted to the opening and closing devices 101, 102 that are now in the closed state. This reduces the risk of damage to the opening and closing devices 101, 102, and improves the operational reliability of the opening and closing devices 101, 102.

[0087] Although it is desirable to include the above-mentioned step ST204, it may be omitted. That is, the control section 100 may proceed to step ST205 after executing step ST203.

[0088] As described above, the air conditioner 1 of this embodiment includes the outdoor unit 20 having the compressor 201, the indoor unit 30, refrigerant pipes 11, 12, 13, and 14 connecting the outdoor unit 20 and the indoor unit 30, opening and closing devices 101 and 102 that open and close the refrigerant pipes 13 and 14, a refrigerant leak sensor 307 that detects the refrigerant concentration, and the control unit 100. When the concentration detected by the refrigerant leak sensor 307 is equal to or greater than a predetermined value, the control unit 100 controls the operating frequency of the compressor 201 to a predetermined value or less, and then closes the opening and closing devices 101 and 102. As a result, after a refrigerant leak is detected, the operating frequency of the compressor 201 is lowered and the opening and closing devices 101 and 102 are controlled to close while the flow rate of the refrigerant flowing through the refrigerant circuit is low, thereby suppressing the impact of the refrigerant transmitted to the opening and closing devices 101 and 102. This reduces the risk of damage to the opening and closing devices 101 and 102, and improves the operational reliability of the opening and closing devices 101 and 102.

[0089] In this embodiment, when the concentration detected by the refrigerant leakage sensor 307 is equal to or greater than a predetermined value, the control unit 100 controls the indoor expansion valve 304 to close, and then closes the opening and closing devices 101 and 102. As a result, after a refrigerant leak is detected, the indoor expansion valve 304 is controlled to close, and the opening and closing devices 101 and 102 are controlled to close while the flow rate of the refrigerant flowing through the refrigerant circuit is low, thereby suppressing the impact of the refrigerant being transmitted to the opening and closing devices. This reduces the risk of damage to the opening and closing devices 101 and 102, and improves the operational reliability of the opening and closing devices 101 and 102.

[0090] [2. Second Embodiment] 9 is a flowchart showing the operation of determining whether to transition to sticking prevention in the air conditioning apparatus 1 of the second embodiment. In the second embodiment, components that are common to the first embodiment are given the same reference numerals and descriptions thereof will be omitted. The control unit 100 of the air conditioner 1 of the second embodiment differs from that of the first embodiment in that it performs control according to the flowchart shown in FIG. 9 instead of the control according to the flowchart shown in FIG. 9, when the control unit 100 starts the process of the transition determination operation for sticking prevention, it determines whether or not the operating frequency of the compressor 201 is equal to or lower than a predetermined value (step ST61). The predetermined value in step ST61 is set to a frequency at which the refrigerant flow rate is small and the refrigerant flow is unlikely to impact the opening and closing devices 101 and 102.

[0091] When the control unit 100 determines that the operation frequency of the compressor 201 is not equal to or lower than the predetermined value (step ST61; NO), the control unit 100 executes the process of step ST61. When the control unit 100 determines that the operating frequency of the compressor 201 is equal to or lower than the predetermined value (step ST61; YES), the control unit 100 executes the sticking prevention operation shown in FIG. 4 in step ST62, and returns to step ST61.

[0092] In this embodiment, the control unit 100 executes the sticking prevention operation when the operating frequency of the compressor 201 is equal to or lower than a predetermined value. This makes it easier to open and close the opening and closing devices 101 and 102 when the flow rate of the refrigerant is low, and the opening and closing devices 101 and 102 are less likely to be impacted by the flow of the refrigerant.

[0093] 3. Third Embodiment 10 is a flowchart showing the operation of determining whether to transition to sticking prevention in the air conditioning apparatus 1 of the third embodiment. In the third embodiment, components that are common to the first and second embodiments are given the same reference numerals and descriptions thereof will be omitted. The operation unit 100a of the air conditioner 1 of the third embodiment is configured to input permission to transition to the sticking prevention operation to the control unit 100. The operation unit 100a corresponds to an example of an input unit.

[0094] The control unit 100 of the air conditioner 1 of the third embodiment differs from that of the first embodiment in that it performs control according to the flowchart shown in FIG. 10 instead of the control according to the flowchart shown in FIG. As shown in FIG. 10, the control unit 100 detects whether or not there is an input from the operation unit 100a, and determines whether or not there is an input for the sticking prevention operation (step ST71).

[0095] When the control unit 100 does not detect the input of the sticking prevention operation (step ST71; NO), the control unit 100 executes the process of step ST71. When the control unit 100 detects an input of the sticking prevention operation (step ST71; YES), the control unit 100 executes the sticking prevention operation shown in FIG. 4 in step ST72, and returns to step ST71.

[0096] In this embodiment, an operation unit 100a is provided for inputting permission to shift to the sticking prevention operation, and the control unit 100 executes the sticking prevention operation when detecting an input from the operation unit 100a. This allows permission to transition to the sticking prevention operation to be input to the control unit 100. Therefore, the control unit 100 can be permitted to transition to the sticking prevention operation at any timing.

[0097] [4. Fourth Embodiment] 11 is a flowchart showing the transition determination operation for abnormality detection of the air conditioning apparatus 1 of the fourth embodiment. In the fourth embodiment, components that are common to the first to third embodiments are given the same reference numerals and descriptions thereof will be omitted. The operation unit 100a of the air conditioning apparatus 1 of the fourth embodiment is configured to input permission to transition to an abnormality detection operation of the opening and closing device to the control unit 100. The operation unit 100a corresponds to an example of a second input unit.

[0098] The control unit 100 of the air conditioner 1 of the fourth embodiment differs from that of the first embodiment in that it performs control according to the flowchart shown in FIG. 11 instead of the control according to the flowchart shown in FIG. As shown in FIG. 11, the control unit 100 detects whether or not there is an input from the operation unit 100a, and determines whether or not there is an input to permit transition to an abnormality detection operation of the switching device (step ST181).

[0099] When the control section 100 does not detect an input of permission to shift to the abnormality detection operation of the switching device (step ST181; NO), the control section 100 executes the process of step ST181. When the control unit 100 detects an input of permission to transition to the abnormality detection operation of the switching device (step ST181; YES), in step ST182, it executes the abnormality detection operation of the switching device shown in FIGS. 6 and 7, and returns to step ST181.

[0100] In this embodiment, an operation unit 100a is provided for inputting permission to transition to an abnormality detection operation of the switching device, and when the control unit 100 detects an input from the operation unit 100a, it executes the abnormality detection operation of the switching device. This allows the control unit 100 to be permitted to transition to the abnormality detection operation of the switching device at any timing.

[0101] 5. Other Embodiments Although the present invention has been described based on the embodiment, the present invention is not limited to this embodiment, which merely illustrates one embodiment of the present invention, and can be arbitrarily modified and applied within the scope of the present invention.

[0102] In the first embodiment, the sticking prevention operation is executed based on the first predetermined time, in the second embodiment, the sticking prevention operation is executed based on the operating frequency of the compressor 201, and in the third embodiment, the sticking prevention operation is executed based on input from the operation unit 100a. However, for example, the sticking prevention operation may be executed based on both the first predetermined time and the operating frequency of the compressor 201. Also, for example, the sticking prevention operation may be executed based on both the operating frequency of the compressor 201 and the input from the operation unit 100a. That is, the flowchart shown in FIG. 3 for the first embodiment, the flowchart shown in FIG. 9 for the second embodiment, and the flowchart shown in FIG. 10 for the third embodiment are not limited to being processed separately by the control unit 100, and may be processed in parallel by the control unit 100.

[0103] In the first to third embodiments, the operation for detecting an abnormality in the switching device is executed based on the second predetermined time and the operating frequency of the compressor 201, and in the fourth embodiment, the operation is executed based on input from the operation unit 100a. However, the operation for detecting an abnormality in the switching device may be executed based on the second predetermined time and the operating frequency of the compressor 201, as well as based on input from the operation unit 100a. That is, the flowcharts shown in FIG. 5 for the first to third embodiments and the flowchart shown in FIG. 11 for the fourth embodiment are not limited to being executed separately by the control unit 100, and may be executed in parallel by the control unit 100.

[0104] In the above embodiment, as an example, the air conditioner 1 has been shown to have the configuration of a packaged air conditioner (PAC) equipped with one outdoor unit 20 and three indoor units 30, but the present invention is not limited to this. For example, the present invention can also be applied to a room air conditioner (RAC) equipped with one outdoor unit 20 and one indoor unit 30, a packaged air conditioner (PAC) in which multiple indoor units are connected to multiple outdoor units, or a multi-air conditioner for buildings (VRF). [Industrial Applicability]

[0105] As described above, the air conditioner according to the present invention can be suitably used as an air conditioner that can suppress the amount of leaking refrigerant even in the event of refrigerant leakage. [Explanation of symbols]

[0106] 1. Air conditioning equipment 11, 13a, 13b, 13c Liquid side piping (refrigerant piping) 12, 14a, 14b, 14c Gas side piping (refrigerant piping) 20 Outdoor unit 30a, 30b, 30c indoor unit 100 control section 100a Operation unit (input unit, second input unit) 101a, 101b, 101c 1st switchgear 102a, 102b, 102c Second opening and closing device 201 Compressor 301a, 301b, 301c Indoor heat exchanger (user side heat exchanger) 302a, 302b, 302c Indoor fans 304a, 304b, 304b Indoor expansion valve (throttle device) 305a, 305b, 305c First temperature sensor 306a, 306b, 306c Second temperature sensor 307a, 307b, 307c Refrigerant Leak Sensor

Claims

1. an outdoor unit having a compressor; an indoor unit having a utilization-side heat exchanger; a refrigerant pipe connecting the outdoor unit and the indoor unit; an opening and closing device disposed on the refrigerant pipe; A control unit; In an air conditioning apparatus comprising: a throttle device for controlling a refrigerant flow rate between the opening and closing device and the utilization-side heat exchanger, the control unit executes a sticking prevention operation for performing an opening and closing operation of the opening and closing device in either a case where there is no refrigerant leakage and the compressor is operating or a case where the compressor is stopped; When the compressor is in operation and there is an indoor unit that is not in operation, the throttle device of the indoor unit that is not in operation is controlled to open, and the throttle device of the indoor unit that is in operation is controlled to close, and the sticking prevention operation is performed for the opening and closing device of the indoor unit that is in operation, and an opening and closing inspection of the opening and closing device is performed. An air conditioning device characterized by:

2. When the sticking prevention operation is performed, if the compressor is stopped, the control unit performs the sticking prevention operation for the opening and closing devices of all of the indoor units, and if the compressor is operating, performs the sticking prevention operation for the opening and closing devices of the indoor units that are not operating, in order to perform an opening and closing inspection of the opening and closing devices.

2. The air conditioning apparatus according to claim 1.

Images