Air conditioner

Abstract

To provide an air conditioner suppressing fastening of an opening / closing device to suppress a leakage amount of refrigerant from an indoor unit.SOLUTION: An air conditioner 1 includes: an outdoor unit 20 having a compressor 201; an indoor unit 30 having a user-side heat exchanger; refrigerant pipes 11, 12, 13, 14 connecting the outdoor unit 20 and the indoor unit 30; opening / closing devices 101, 102 arrange to the refrigerant pipes 13, 14; and a control part 100. The air conditioner is provided with a throttle device controlling a refrigerant flow rate between the opening / closing devices 101, 102 and the user-side heat exchanger. The control part 100 executes a fastening prevention operation of the opening / closing devices 101, 102 when the refrigerant is not leaked, controls the throttle device of the indoor unit 30 in stop of operation to open and also controls the throttle device of the indoor unit 30 in operation to close when the compressor 201 is in operation and also when the operation of the indoor unit 30 is stopped, and executes the fastening prevention operation with respect to the opening / closing devices 101, 102 of the indoor unit 30 in operation.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an air conditioner.

Background Art

[0002] Conventionally, in an air conditioner, a configuration is known in which an opening / closing device is provided in a refrigerant pipe to suppress the amount of refrigerant leakage when refrigerant leakage occurs (see, for example, Patent Document 1). In Patent Document 1, during cooling operation, the throttle device of the outdoor unit is controlled to make the refrigerant flowing through the liquid side pipe in a gas-liquid two-phase state. When refrigerant leakage is detected, the opening / closing device upstream of the indoor heat exchanger and the opening / closing device downstream thereof are closed to reduce the amount of refrigerant leakage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional air conditioner, the opening / closing device is not closed unless refrigerant leakage occurs. Therefore, there is a risk of sticking due to not closing the opening / closing device for a long time. If sticking of the opening / closing device occurs, the opening / closing device cannot be closed when refrigerant leakage occurs, and there is a risk of an increase in the amount of refrigerant leakage from the indoor unit. The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress sticking of an opening / closing device and suppress the amount of refrigerant leakage from an indoor unit in an air conditioner.

Means for Solving the Problems

[0005] In order to solve the above problems, the present invention provides an air conditioner including an outdoor unit having a compressor, an indoor unit having a user-side heat exchanger, a refrigerant pipe connecting the outdoor unit and the indoor unit, an opening / closing device disposed in the refrigerant pipe, and a control unit. The air conditioner further includes a throttling device for controlling the refrigerant flow rate between the opening / closing device and the user-side heat exchanger. The control unit executes a sticking prevention operation for opening and closing the opening / closing device when no refrigerant leakage occurs. When the compressor is in operation and there is an indoor unit that is stopped, the control unit controls the throttling device of the stopped indoor unit to open and controls the throttling device of the operating indoor unit to close, and executes the sticking prevention operation for the opening / closing device of the operating indoor unit. According to this, even when no refrigerant leakage occurs, the opening / closing device can be opened and closed, so that sticking of the opening / closing device can be suppressed.

Effects of the Invention

[0006] According to the present invention, sticking of the opening / closing device can be suppressed. Therefore, when refrigerant leakage occurs, the opening / closing device can be easily and appropriately operated, and the amount of refrigerant leaking from the indoor unit can be effectively suppressed.

Brief Description of the Drawings

[0007]

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Mode for Carrying Out the Invention

[0008] A first invention is an air conditioner including 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 / closing device disposed in the refrigerant pipe, and a control unit. The air conditioner includes a throttle device for controlling the refrigerant flow rate between the opening / closing device and the utilization-side heat exchanger. The control unit executes a sticking prevention operation of opening and closing the opening / closing device when no refrigerant is leaking. When the compressor is operating and there is an indoor unit that is stopped, the throttle device of the stopped indoor unit is controlled to open, and the throttle device of the operating indoor unit is controlled to close, and the sticking prevention operation is executed for the opening / closing device of the operating indoor unit. Thereby, it is possible to prevent the opening / closing device from not opening and closing for a long time and suppress the sticking of the opening / closing device. For this reason, when refrigerant leakage occurs, it is easy to appropriately operate the opening / closing device, and the amount of refrigerant leaking from the indoor unit can be effectively suppressed. Also, thereby, it is easy to increase the refrigerant flow rate in the stopped indoor unit and easy to decrease the refrigerant flow rate in the operating indoor unit. For this reason, the opening / closing device corresponding to the operating indoor unit can be opened and closed in a state where it is hardly affected by the refrigerant flow. Also, since the refrigerant can be flowed using the stopped indoor unit, an excessive pressure increase in the refrigerant circuit can be suppressed even when the opening / closing device is opened and closed.

[0009] The second invention is that the refrigerant pipe has a liquid-side pipe and a gas-side pipe, and the opening / closing device has a first opening / closing device for opening / closing the liquid-side pipe connected to the indoor unit and a second opening / closing device for opening / closing the gas-side pipe connected to the indoor unit. Accordingly, each of the liquid-side pipe and the gas-side pipe connected to the indoor unit can be opened and closed, and when refrigerant leakage occurs, the amount of refrigerant leaking from the indoor unit can be effectively suppressed.

[0010] The third invention is that the control unit executes the anti-seizure operation for opening and closing the first opening / closing device and the second opening / closing device. Accordingly, it is possible to prevent the first opening / closing device and the second opening / closing device from not being opened and closed for a long period of time, and to suppress the seizure of the first opening / closing device and the second opening / closing device. For this reason, when refrigerant leakage occurs, the liquid-side pipe and the gas-side pipe connected to the indoor unit can be appropriately opened and closed.

[0011] The fourth invention is that a throttle device for controlling the refrigerant flow rate between the first opening / closing device and the utilization-side heat exchanger is provided in the liquid-side pipe. Accordingly, the refrigerant flow rate flowing through the utilization-side heat exchanger can be controlled by the throttle device.

[0012] The fifth invention is that a plurality of the indoor units arranged in parallel are provided, and for each indoor unit, the first opening / closing device and the second opening / closing device are provided, and for each indoor unit, the throttle device is provided. Accordingly, in an air conditioner including a plurality of the indoor units arranged in parallel, the amount of refrigerant leaking from each indoor unit can be effectively suppressed.

[0013] The sixth invention is that when the control unit executes the anti-seizure operation, if the compressor is stopped, the anti-seizure operation is executed for the opening / closing devices of all the indoor units. Accordingly, for all the indoor units, it is possible to execute the anti-seizure operation of the opening / closing device while suppressing the impact received from the refrigerant flow.

[0014] The seventh invention is that when the control unit executes the sticking prevention operation, if the compressor is in operation and there are a plurality of indoor units in operation, the throttle device of the first indoor unit in operation is controlled to close, and after executing the sticking prevention operation for the opening / closing device of the first indoor unit in operation, the throttle device of the second indoor unit in operation is controlled to close, and the sticking prevention operation is executed for the opening / closing device of the second indoor unit in operation. Accordingly, when executing the sticking prevention operation, if the compressor is in operation and there are a plurality of indoor units in operation, the sticking prevention operation is executed separately for the first indoor unit in operation and the second indoor unit in operation. For this reason, when executing the sticking prevention operation for the opening / closing device of one of the first and second indoor units in operation, the other of the first and second indoor units in operation can be used to flow the refrigerant, so that an excessive pressure rise in the refrigerant circuit can be suppressed.

[0015] The eighth invention is that when the control unit executes the sticking prevention operation, the sticking prevention operation is executed for the opening / closing device of the indoor unit during operation stop. Accordingly, when the compressor is in operation, the sticking prevention operation can be executed for the opening / closing device of the indoor unit during operation stop.

[0016] The ninth invention is that after the control unit executes the sticking prevention operation and after a first predetermined time has elapsed, the sticking prevention operation is executed again. Accordingly, the sticking prevention operation can be executed every first predetermined time, and the sticking prevention operation can be executed with a necessary and sufficient frequency.

[0017] The tenth invention is that the control unit executes the sticking prevention operation when the operating frequency of the compressor is equal to or less than a predetermined value. Accordingly, it is easy to open and close the opening / closing device in a state where the flow rate of the refrigerant is small, and the opening / closing device is less likely to be impacted by the flow of the refrigerant.

[0018] The eleventh invention includes an input unit for inputting permission to shift to the sticking prevention operation, and the control unit executes the sticking prevention operation when it detects the input by the input unit. Thereby, it is possible to input to the control unit a permission to shift to the sticking prevention operation. Therefore, the control unit can be permitted to shift to the sticking prevention operation at an arbitrary timing.

[0019] According to a twelfth aspect of the invention, in a state where the throttle device is open, the control unit controls at least one of the first opening / closing device and the second opening / closing device to be closed, and executes an abnormality determination control for determining an abnormal state of the opening / closing device that has been closed among the first opening / closing device and the second opening / closing device. Thereby, it is possible to determine an abnormal state between the first opening / closing device and the second opening / closing device based on whether or not the refrigerant flowing in the indoor unit is blocked by the opening / closing device that has been closed.

[0020] According to a thirteenth aspect of the invention, there are provided a first temperature sensor that is disposed in the liquid-side pipe between the first opening / closing device and the utilization-side heat exchanger and detects a refrigerant temperature, and a second temperature sensor that is disposed in the gas-side pipe between the second opening / closing device and the utilization-side heat exchanger and detects a refrigerant temperature. In the abnormality determination control, the control unit controls one of the first opening / closing device and the second opening / closing device to be open and the other opening / closing device to be closed, and determines that the other opening / closing device is in an abnormal state when a difference value between the detected temperatures of the first temperature sensor and the second temperature sensor is higher than a predetermined temperature. Thereby, it is possible to detect the refrigerant temperature between the first opening / closing device and the utilization-side heat exchanger and the refrigerant temperature between the second opening / closing device and the utilization-side heat exchanger. Therefore, it is possible to determine whether or not the refrigerant is blocked based on the temperature difference between the liquid side and the gas side of the utilization-side heat exchanger, and to determine the abnormal state of the opening / closing device.

[0021] According to a fourteenth aspect of the invention, in the abnormality determination control, the control unit throttles the throttle device, controls the opening / closing device on the upstream side in the refrigerant flow direction among the first opening / closing device and the second opening / closing device to be open, and controls the opening / closing device on the downstream side to be closed, and determines whether or not the opening / closing device on the downstream side is in an abnormal state. Thereby, since the refrigerant flow rate flowing to the opening / closing device on the downstream side is reduced by the throttle device and the opening / closing device on the downstream side in the refrigerant flow direction is controlled to be closed, the impact received by the opening / closing device from the refrigerant can be suppressed.

[0022] In the 15th invention, in the abnormality determination control, after determining whether or not the downstream opening / closing device is in an abnormal state, the control unit performs open control on the downstream opening / closing device and closes the upstream opening / closing device to control, and determines whether or not the upstream opening / closing device is in an abnormal state. Thereby, it is also possible to determine the abnormal state of the opening / closing device on the upstream side in the refrigerant flow direction.

[0023] In the 16th invention, when the control unit determines that the opening / closing device is in an abnormal state in the abnormality determination control, the control unit notifies that the opening / closing device is in an abnormal state. Thereby, it is easy to recognize that the opening / closing device is in an abnormal state.

[0024] In the 17th invention, when the operating frequency of the compressor is equal to or lower than a predetermined value, if a second predetermined time has elapsed after the abnormality determination control is executed, the control unit executes the abnormality determination control again. Thereby, when the impact received from the refrigerant flow is small, the opening / closing device can be opened / closed to execute the abnormality determination control. In addition, excessive execution of the abnormality determination control can be suppressed.

[0025] The 18th invention includes a second input unit for inputting permission to shift to the abnormality determination control, and when the control unit detects the input by the second input unit, the control unit executes the abnormality determination control. Thereby, the control unit can be permitted to shift to the abnormality determination control at an arbitrary timing.

[0026] In the 19th invention, in the abnormality determination control, when the control unit determines that at least one of the first opening / closing device and the second opening / closing device is in an abnormal state, the control unit performs close control on the throttle device. Thereby, when the opening / closing device is in an abnormal state, the throttle device can be closed to control the refrigerant flow.

[0027] The 20th invention is that the indoor unit is provided with a refrigerant leakage sensor for detecting the refrigerant concentration, and when the detected concentration of the refrigerant leakage sensor is equal to or higher than a predetermined value, the control unit controls the operating frequency of the compressor to be equal to or lower than a predetermined value and then sets the opening / closing device to a closed state. Thereby, after detecting refrigerant leakage, by reducing the operating frequency of the compressor and controlling the opening / closing device to be closed in a state where the flow rate of the refrigerant flowing through the refrigerant circuit is small, the impact of the refrigerant transmitted to the opening / closing device is suppressed. As a result, the risk of damage to the opening / closing device can be reduced, and the operation reliability of the opening / closing device can be improved.

[0028] The 21st invention is that when the detected concentration of the refrigerant leakage sensor is equal to or higher than a predetermined value, the control unit controls the throttle device to be closed and then sets the opening / closing device to a closed state. Thereby, after detecting refrigerant leakage, by controlling the throttle device to be closed and controlling the opening / closing device to be closed in a state where the flow rate of the refrigerant flowing through the refrigerant circuit is small, the impact of the refrigerant transmitted to the opening / closing device is suppressed. For this reason, the risk of damage to the opening / closing device can be reduced, and the operation reliability of the opening / closing device can be improved.

[0029] Hereinafter, an embodiment of the present invention will be described with reference to the 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 includes an outdoor unit 20 and a plurality of indoor units 30a, 30b, 30c. Each of the indoor units 30a, 30b, 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 includes liquid-side pipes 13a, 13b, 13c that branch and are connected to each of the indoor units 30a, 30b, 30c. The gas-side pipe 12 includes gas-side pipes 14a, 14b, 14c that branch and are connected to each of the indoor units 30a, 30b, 30c. The air conditioner 1 circulates the refrigerant compressed by the outdoor unit 20 between the outdoor unit 20 and the indoor units 30a, 30b, 30c to air-condition the conditioned space in which the indoor units 30a, 30b, 30c are installed.

[0030] Since the indoor units 30a, 30b, and 30c are configured in the same manner, in the following description, the corresponding components of the indoor units 30a, 30b, and 30c are assigned the same numerical reference signs and are distinguished by adding subscripts a, b, and c. Further, when there is no particular need to distinguish the corresponding components, only the numerical reference signs are used, and the subscripts a, b, and c may be omitted.

[0031] The outdoor unit 20 includes a compressor 201 that compresses refrigerant, an outdoor heat exchanger 202 that performs heat exchange of the refrigerant, an outdoor fan 203, an expansion valve 204, and a switching valve 205. The compressor 201 sucks 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.

[0032] The outdoor fan 203 blows air to the outdoor heat exchanger 202. The expansion valve 204 reduces the pressure of the high-pressure refrigerant and expands it. The expansion valve 204 is configured to be able to adjust its opening degree. The opening degree of the expansion valve 204 is controlled by the control unit 100. The expansion valve 204 may be a valve that can adjust its opening degree and block the refrigerant. The switching valve 205 is composed of, for example, a four-way valve. The switching valve 205 switches the flow of the discharged refrigerant from the compressor 201 and the refrigerant returning to the compressor 201. By the switching valve 205, the cooling operation mode and the heating operation mode of the air conditioner 1 are switched.

[0033] 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 refrigerant supplied from the outdoor unit 20 through the liquid-side pipe 11 or the gas-side pipe 12 and the indoor air. The indoor heat exchanger 301 corresponds to an example of the utilization-side heat exchanger. The indoor fan 302 blows air to the indoor heat exchanger 301.

[0034] The indoor expansion valve 304 is an expansion valve disposed in the liquid side pipe 11 between the expansion valve 204 and the indoor heat exchanger 301. In the present embodiment, the indoor expansion valve 304 is disposed in the liquid side pipe 13 connected to the indoor heat exchanger 301. The indoor expansion valve 304 is configured in the same manner as the expansion valve 204. The indoor expansion valve 304 corresponds to an example of a throttling device.

[0035] A first temperature sensor 305 is provided in the liquid side pipe 13 of the indoor heat exchanger 301. In the present embodiment, the first temperature sensor 305 is provided at the 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 the present embodiment, the second temperature sensor 306 is provided at the 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.

[0036] 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 higher than a predetermined value, leakage of the refrigerant is detected.

[0037] On both sides of the indoor heat exchanger 301 of the indoor unit 30, a first opening / closing device 101 and a second opening / closing device 102 for adjusting the flow rate of the refrigerant to the indoor unit 30 are provided.

[0038] The first opening / closing device 101 is provided in the liquid side pipe 13 connected to the indoor heat exchanger 301. The first opening / closing device 101 of the present embodiment is composed of an opening / closing valve such as an electric valve or a solenoid valve. The first opening / closing device 101 can switch 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 / closing device 101 is configured such that its opening and closing can be controlled by the control unit 100. Further, the first opening / closing device 101 is configured to be in the closed state during a power failure. Note that the first opening / closing device 101 may be a valve capable of setting a state between an open state and a closed state, or may be configured such that the opening degree of the first opening / closing device 101 is controlled by the control unit 100.

[0039] The second opening / closing device 102 is provided in the gas-side pipe 14 connected to the indoor heat exchanger 301. The second opening / closing device 102 is configured in the same manner as the first opening / closing device 101.

[0040] In the cooling operation mode of the air conditioner 1, the refrigerant flows in the flow direction F1, and the refrigerant flows in the order of 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, and returns from the switching valve 205 to the suction pipe 208.

[0041] Also, in the heating operation mode of the air conditioner 1, the refrigerant flows in the flow direction F2, and the refrigerant flows in the order of the compressor 201, the switching valve 205, the indoor heat exchanger 301, the indoor expansion valve 304, the expansion valve 204, the outdoor heat exchanger 202, and the switching valve 205, and returns from the switching valve 205 to the suction pipe 208.

[0042] FIG. 2 is a block diagram of the control unit 100 of the air conditioner 1 according to the first embodiment. As shown in FIGS. 1 and 2, the air conditioner 1 includes a control unit 100. An operation unit 100a composed of a remote control, an operation panel, etc. is connected to the control unit 100 by wire or wirelessly. A display unit 100b is provided in the operation unit 100a. The display unit 100b is configured to display the operation state of the operation unit 100a and the operation state of the air conditioner 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.

[0043] 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 switching the flow path of the switching valve 205, and control of the operation and stop of the outdoor fan 203 and the indoor fan 302. Further, the control unit 100 executes control of the opening and closing of the first opening / closing device 101 and the second opening / closing device 102.

[0044] 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. Further, the control unit 100 executes control of the operating frequency, operation and stop of the compressor 201, and control of the outdoor fan 203 and the indoor fan 302 in accordance with the target temperature set by an operation on the operation unit 100a, and air-conditions the conditioned space in accordance with the target temperature.

[0045] The control unit 100 executes the process of the sticking prevention operation. In order to execute the process of the sticking prevention operation, the control unit 100 executes the process of the transition determination operation of the sticking prevention of the air conditioner 1. Further, the control unit 100 executes the process of the abnormality detection operation of the opening / closing device. In order to execute the process of the abnormality detection operation of the opening / closing device, the control unit 100 executes the process of the transition determination operation of the abnormality detection of the air conditioner 1. Furthermore, the control unit 100 executes the process of the refrigerant leakage detection operation of the air conditioner 1.

[0046] Various refrigerants are 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 slightly flammable or flammable. When a slightly flammable or flammable refrigerant leaks, it is required 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 the indoor unit 30 installed in the conditioned space or in its vicinity.

[0047] FIG. 3 is a flowchart showing the transition determination operation of sticking prevention of the air conditioner 1 according to the first embodiment. FIG. 4 is a flowchart showing the sticking prevention operation of the air conditioner 1. The operations in FIGS. 3 and 4 are executed by the control unit 100 controlling each part of the air conditioner 1.

[0048] As shown in FIG. 3, when the control unit 100 starts the process of the sticking prevention transition determination operation, it starts measuring the first predetermined time (step ST11). The first predetermined time is a time for setting the interval at which the sticking prevention operation is executed. With the first predetermined time, the first opening / closing device 101 and the second opening / closing device 102 can be opened and closed at a necessary and sufficient frequency, and it is possible to suppress excessive opening and closing and wear of the opening / closing devices 101 and 102. In the present 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 the first predetermined time has elapsed (step ST12).

[0049] 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). When the control unit 100 executes the sticking prevention operation, it 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.

[0050] 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). When the control unit 100 determines that the compressor 201 is in operation (step ST21; YES), it determines whether the number of operating indoor units 30 is one (step ST22).

[0051] When 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 in the stopped state as an example of opening control (step ST23). In the present embodiment, the indoor expansion valves 304 of all the indoor units 30 that are in the stopped state are fully opened. This allows the refrigerant to flow through the indoor unit 30 that is in the stopped state. Since the refrigerant can flow through the indoor unit 30 that is in the stopped state, even if the flow of the refrigerant is blocked in the operating indoor unit 30, an excessive pressure increase in the refrigerant circuit is suppressed. Here, instead of the configuration in which the indoor expansion valves 304 of all the indoor units 30 that are in the stopped state are fully opened, a configuration in which the indoor expansion valves 304 of some of the indoor units 30 that are in the stopped state are fully opened may be adopted. In this case, for example, the indoor units 30a and 30b on the outdoor unit 20 side may be fully opened.

[0052] The control unit 100 closes the control the indoor expansion valve 304 of the operating indoor unit 30 (step ST24). The closing control in step ST24 controls the opening degree of the indoor expansion valve 304 so that the opening degree becomes closer to the fully closed side than the current state. This suppresses the flow rate of the refrigerant flowing through the operating indoor unit 30 and suppresses the impact received by the opening / closing devices 101 and 102 from the refrigerant flow when they open and close.

[0053] The control unit 100 sets the first opening / closing device 101 corresponding to the operating indoor unit 30 to the closed state (step ST25). The control unit 100 sets the first opening / closing device 101 corresponding to the operating indoor unit 30 to the open state (step ST26). The control unit 100 sets the second opening / closing device 102 corresponding to the operating indoor unit 30 to the closed state (step ST27). The control unit 100 sets the second opening / closing device 102 corresponding to the operating indoor unit 30 to the open state (step ST28). In steps ST25 to ST28, since the first opening / closing device 101 and the second opening / closing device 102 of the indoor unit 30 that was in the operating state are opened and closed, sticking of the first opening / closing device 101 and the second opening / closing device 102 is prevented.

[0054] The control unit 100 performs an opening control of the indoor expansion valve 304 of the indoor unit 30 during operation (step ST29). The opening control in step ST29 controls the opening degree of the indoor expansion valve 304 so as to be the opening degree before the closing control of the indoor expansion valve 304 in step ST24. Thereby, the refrigerant flows through the indoor unit 30 at the same flow rate as during operation. The control unit 100 fully closes the indoor expansion valve 304 of the indoor unit 30 that was fully opened during the stop of operation in step ST23 (step ST30). Thereby, the flow of the refrigerant is blocked for the indoor unit 30 during the stop of operation.

[0055] The control unit 100 sets the first on-off device 101 corresponding to the indoor unit 30 during the stop of operation to the closed state (step ST31). The control unit 100 sets the first on-off device 101 corresponding to the indoor unit 30 during the stop of operation to the open state (step ST32). The control unit 100 sets the second on-off device 102 corresponding to the indoor unit 30 during the stop of operation to the closed state (step ST33). The control unit 100 sets the second on-off device 102 corresponding to the indoor unit 30 during the stop of operation to the open state (step ST34). In steps ST31 to ST34, the first on-off device 101 and the second on-off device 102 corresponding to the indoor unit 30 that was in the stop of operation are opened and closed, so that the sticking of the first on-off device 101 and the second on-off device 102 is prevented. Then, the control unit 100 ends the sticking prevention operation when the number of operating indoor units 30 is one.

[0056] When the number of operating indoor units 30 is not one, that is, when the number of operating indoor units 30 is plural (step ST22; NO), the control unit 100 performs setting of grouping into "first-start" and "later-start" groups for the operating indoor units 30 (step ST41). For the "first-start" and "later-start" groups, at least one or more of the operating indoor units 30 may be set. As long as one or more are set, the method of setting the "first-start" and "later-start" groups is arbitrary. In the present embodiment, when the indoor unit 30a is in operation, the indoor unit 30a is set to "first-start", and the remaining operating indoor units 30b and 30c are configured to be set to "later-start". Also, when the indoor unit 30a is in the stopped state, the indoor unit 30b is set to "first-start", and the indoor unit 30c is configured to be set to "later-start". The "first-start" operating indoor unit 30 corresponds to an example of the first operating indoor unit 30. Also, the "later-start" operating indoor unit 30 corresponds to an example of the second operating indoor unit 30.

[0057] The control unit 100 performs closing control on the indoor expansion valve 304 of the "first-start" operating indoor unit 30 (step ST42). The closing control in step ST42 is the same closing control as in step ST24. The control unit 100 sets the opening / closing devices 101 and 102 corresponding to the "first-start" operating indoor unit 30 to the closed state (step ST43). The control unit 100 sets the opening / closing devices 101 and 102 corresponding to the "first-start" operating indoor unit 30 to the open state (step ST44). By steps ST43 to ST44, since the first opening / closing device 101 and the second opening / closing device 102 corresponding to the "first-start" operating indoor unit 30 are opened and closed, sticking of the first opening / closing device 101 and the second opening / closing device 102 is prevented. At this time, since the refrigerant can flow in the "later-start" operating indoor unit 30, an excessive pressure increase in the refrigerant circuit is suppressed. The control unit 100 performs opening control on the indoor expansion valve 304 corresponding to the "first-start" operating indoor unit 30 (step ST45). The opening control in step ST45 is the same opening control as in step ST29.

[0058] The control unit 100 performs closing control on the indoor expansion valve 304 corresponding to the indoor unit 30 during the "subsequent start" operation (step ST46). The closing control in step ST46 is the same as the closing control in step ST24. The control unit 100 sets the opening / closing devices 101 and 102 corresponding to the indoor unit 30 during the "subsequent start" operation to the closed state (step ST47). The control unit 100 sets the opening / closing devices 101 and 102 corresponding to the indoor unit 30 during the "subsequent start" operation to the open state (step ST48). In steps ST47 to ST48, since the first opening / closing device 101 and the second opening / closing device 102 corresponding to the indoor unit 30 during the "subsequent start" operation are opened and closed, sticking of the first opening / closing device 101 and the second opening / closing device 102 is prevented. At this time, since the refrigerant can flow in the indoor unit 30 during the "prior start" operation, an excessive pressure increase in the refrigerant circuit is suppressed. The control unit 100 performs opening control on the indoor expansion valve 304 corresponding to the indoor unit 30 during the "subsequent start" operation (step ST49). The opening control in step ST49 is the same as the opening control in step ST29.

[0059] The control unit 100 determines whether there is an indoor unit 30 that is stopped (step ST50). When the control unit 100 determines that there is no indoor unit 30 that is stopped (step ST50; YES), it ends the sticking prevention operation when there are multiple indoor units 30 in operation.

[0060] When the control unit 100 determines that there is an indoor unit 30 that is stopped (step ST50; NO), it executes the processes of steps ST31 to ST34 for the indoor unit 30 that is stopped. Then, the control unit 100 ends the sticking prevention operation when there are multiple indoor units 30 in operation.

[0061] When the control unit 100 determines that the compressor 201 is stopped (step ST21; NO), it sets the first opening / closing device 101 corresponding to all the indoor units 30 to the closed state (step ST51). The control unit 100 sets the first opening / closing device 101 corresponding to all the indoor units 30 to the open state (step ST52). The control unit 100 closes the second opening / closing devices 102 corresponding to all the indoor units 30 (step ST53). The control unit 100 opens the second opening / closing devices 102 corresponding to all the indoor units 30 (step ST54). In steps ST51 to ST54, since the first opening / closing device 101 and the second opening / closing device 102 corresponding to the indoor unit 30 during operation stop are opened and closed, sticking of the first opening / closing device 101 and the second opening / closing device 102 is prevented. At this time, since the compressor 201 is stopped and the refrigerant is not flowing, the 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.

[0062] Here, in the conventional configuration described in Patent Document 1, as long as refrigerant leakage does not occur, the opening / closing device is not closed. For this reason, there is a risk of sticking due to not closing the opening / closing device for a long time. Therefore, when refrigerant leakage actually occurs, the opening / closing device does not function properly, the refrigerant circuit cannot be shut off, and there is a problem that the amount of refrigerant leakage increases.

[0063] On the other hand, in the present embodiment, by the processes of steps ST25 to ST28, steps ST31 to ST34, steps ST43 to ST44, steps ST47 to ST48, and steps ST51 to ST54, the opening / closing devices 101 and 102 are opened and closed even when the refrigerant is not leaking. As a result, the opening / closing devices 101 and 102 move between the closed state (fully closed) and the open state (fully open), and sticking of the opening / closing devices can be suppressed. For this reason, when refrigerant leakage occurs, the opening / closing devices 101 and 102 can be easily operated appropriately, and the amount of refrigerant leaking from the indoor unit 30 can be effectively suppressed.

[0064] In the present embodiment, in steps ST25 to ST28 described above, after opening and closing the first opening / closing device 101, the second opening / closing device 102 is opened and closed. However, instead of this, after opening and closing the second opening / closing device 102, the first opening / closing device 101 may be opened and closed. Also, the first opening / closing device 101 and the second opening / closing device 102 may be opened and closed simultaneously. Similarly, in the present embodiment, in the above-described steps ST31 to ST34, after opening and closing the first opening / closing device 101, the second opening / closing device 102 may be opened and closed. Alternatively, after opening and closing the second opening / closing device 102, the first opening / closing device 101 may be opened and closed, or the first opening / closing device 101 and the second opening / closing device 102 may be opened and closed simultaneously.

[0065] Also, in the present embodiment, in the above-described steps ST31 to ST34, all the opening / closing devices 101 and 102 of the indoor unit 30 during operation stop are opened and closed simultaneously. However, alternatively, steps ST31 to ST34 may be executed for each indoor unit 30 during operation stop, and the opening / closing devices 101 and 102 may be opened and closed in the order of the opening / closing devices 101 and 102 of the indoor unit 30 during operation stop, thereby opening and closing all the opening / closing devices 101 and 102 of the indoor unit 30 during operation stop.

[0066] As described above, the air conditioner 1 of the present embodiment includes an outdoor unit 20 having a compressor 201, an indoor unit 30 having an indoor heat exchanger 301, liquid-side pipes 11 and 13 and gas-side pipes 12 and 14 connecting the outdoor unit 20 and the indoor unit 30, opening / closing devices 101 and 102 disposed in the liquid-side pipe 13 and the gas-side pipe 14, and a control unit 100. In this air conditioner 1, the control unit 100 executes a sticking prevention operation for opening and closing the opening / closing devices 101 and 102 when the refrigerant is not leaking. Thereby, it is possible to prevent the opening / closing devices 101 and 102 from not opening and closing for a long time and suppress the sticking of the opening / closing devices 101 and 102. For this reason, when refrigerant leakage occurs, it is easy to appropriately operate the opening / closing devices 101 and 102, and the amount of refrigerant leaking from the indoor unit 30 can be effectively suppressed.

[0067] In the present embodiment, the refrigerant pipe has liquid-side pipes 11 and 13 and gas-side pipes 12 and 14. The opening / closing device has a first opening / closing device 101 that opens and closes the liquid-side pipe 13 connected to the indoor unit 30 and a second opening / closing device 102 that opens and closes the gas-side pipe 14 connected to the indoor unit 30. As a result, each of the liquid-side pipe 13 and the gas-side pipe 14 connected to the indoor unit 30 can be opened and closed, and when refrigerant leakage occurs, the amount of refrigerant leaking from the indoor unit 30 can be effectively suppressed.

[0068] Further, in the present embodiment, the control unit 100 executes a sticking prevention operation for opening and closing the first opening / closing device 101 and the second opening / closing device 102. Thereby, it is possible to prevent the first opening / closing device 101 and the second opening / closing device 102 from not being opened and closed for a long time, and it is possible to suppress the sticking of the first opening / closing device 101 and the second opening / closing device 102. For this reason, when refrigerant leakage occurs, the liquid-side pipe 11 and the gas-side pipe 12 connected to the indoor unit 30 can be appropriately opened and closed.

[0069] Further, in the present embodiment, an indoor expansion valve 304 for controlling the refrigerant flow rate between the first opening / closing device 101 and the indoor heat exchanger 301 is provided in the liquid-side pipe 11. Thereby, the refrigerant flow rate flowing through the indoor heat exchanger 301 can be controlled by the indoor expansion valve 304.

[0070] Further, in the present embodiment, a plurality of indoor units 30a, 30b, 30c arranged in parallel are provided, and for each of the indoor units 30a, 30b, 30c, a first opening / closing device 101a, 101b, 101c and a second opening / closing device 102a, 102b, 102c are provided, and for each of the indoor units 30a, 30b, 30c, indoor expansion valves 304a, 304b, 304c are provided. Thereby, in the air conditioner 1 including a plurality of indoor units 30a, 30b, 30c arranged in parallel, the amount of refrigerant leaking from each of the indoor units 30a, 30b, 30c can be effectively suppressed.

[0071] Further, in the present embodiment, when the control unit 100 executes the sticking prevention operation, if the compressor 201 is stopped, the sticking prevention operation is executed for the opening / closing devices 101, 102 of all the indoor units 30. Thereby, for all the indoor units 30, it is possible to execute the sticking prevention operation of the opening / closing devices 101, 102 while suppressing the impact received from the refrigerant flow.

[0072] Also, in the present 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 stopped, the indoor expansion valve 304 of the stopped indoor unit 30 is controlled to open, and the indoor expansion valve 304 of the operating indoor unit 30 is controlled to close, and the sticking prevention operation is executed for the opening and closing devices 101 and 102 of the operating indoor unit 30. Thereby, in the stopped indoor unit 30, it is easier to increase the refrigerant flow rate, and in the operating indoor unit 30, it is easier to decrease the refrigerant flow rate. For this reason, the opening and closing devices 101 and 102 corresponding to the operating indoor unit 30 can be opened and closed in a state where they are hardly affected by the refrigerant flow. Further, since the refrigerant can be circulated using the stopped indoor unit 30, an excessive pressure increase in the refrigerant circuit can be suppressed even when the opening and closing devices 101 and 102 are opened and closed.

[0073] Also, in the present embodiment, when the control unit 100 executes the sticking prevention operation, if the compressor 201 is in operation and there are a plurality of operating indoor units 30, the indoor expansion valve 304 of the "earlier-started" operating indoor unit 30 is controlled to close, and the sticking prevention operation is executed for the opening and closing devices 101 and 102 of the "earlier-started" operating indoor unit 30. Then, thereafter, the indoor expansion valve 304 of the "later-started" operating indoor unit 30 is controlled to close, and the sticking prevention operation is executed for the opening and closing devices 101 and 102 of the "later-started" operating indoor unit 30. Thereby, when the sticking prevention operation is executed, if the compressor 201 is in operation and there are a plurality of operating indoor units 30, the sticking prevention operation is executed separately for the "earlier-started" operating indoor unit 30 and the "later-started" operating indoor unit 30. For this reason, when the sticking prevention operation is executed for the opening and closing devices 101 and 102 of one of the "earlier-started" and "later-started" operating indoor units 30, the refrigerant can be circulated using the other operating indoor unit 30 of the "earlier-started" and "later-started", so that an excessive pressure increase in the refrigerant circuit can be suppressed.

[0074] Further, in the present embodiment, when executing the anti-seizure operation, the control unit 100 executes the anti-seizure operation for the opening / closing devices 101 and 102 of the indoor unit 30 during the operation stop. Thereby, when the compressor 201 is in operation, the anti-seizure operation can be executed for the opening / closing devices 101 and 102 of the indoor unit during the operation stop.

[0075] Also, in the present embodiment, the control unit 100 executes the anti-seizure operation again after the elapse of the first predetermined time since the execution of the anti-seizure operation. Thereby, the anti-seizure operation can be executed every first predetermined time, and the anti-seizure operation can be executed at a necessary and sufficient frequency.

[0076] FIG. 5 is a flowchart showing the transition determination operation of the abnormality detection of the air conditioner 1 according to the first embodiment. FIG. 6 is a flowchart showing the abnormality detection operation of the opening / closing device of the air conditioner 1. FIG. 7 is a flowchart showing the remainder of FIG. 6. The operations of FIGS. 5 to 7 are executed by the control unit 100 controlling each part of the air conditioner 1.

[0077] As shown in FIG. 5, when starting the process of the transition determination operation of the abnormality detection, the control unit 100 starts measuring the second predetermined time (step ST101). The second predetermined time is the shortest time interval for executing the abnormality detection operation. Thereby, it is possible to suppress performing the abnormality detection operation of the opening / closing device excessively. That is, it is possible to suppress excessively opening and closing the first opening / closing device 101 and the second opening / closing device 102 and wearing out the opening / closing devices 101 and 102. In the present embodiment, as an example, one month is set as the second predetermined time.

[0078] The control unit 100 determines whether there is an instruction for the down control of the operating frequency of the compressor 201 (step ST102). When there is no instruction for the down control of 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 compressor 201 to decrease its operating frequency (step ST102; YES), the control unit 100 determines whether the operating frequency of the compressor 201 is less than or equal to a predetermined value (step ST103). The predetermined value in step ST103 is set to an operating frequency at which the refrigerant flow rate is low and the opening / closing devices 101 and 102 are less likely to be impacted by the refrigerant flow when the opening / closing devices 101 and 102 are opened / closed.

[0079] When the control unit 100 determines that the operating frequency of the compressor 201 is not less than or equal to the predetermined value (step ST103; NO), it executes the process of step ST102. When the control unit 100 determines that the operating frequency of the compressor 201 is less than or equal to the predetermined value (step ST103; YES), it determines whether the operating frequency is not zero (step ST103). When the control unit 100 determines that the operating frequency of the compressor 201 is zero (step ST104; NO), it stops the operation of the air conditioner 1 (step ST107) and executes the process of step ST102.

[0080] When the control unit 100 determines that the operating frequency of the compressor 201 is not zero (step ST104; YES), it determines whether a second predetermined time has elapsed (step ST105). Thereby, it determines whether the second predetermined time has elapsed in a state where the refrigerant flow rate is low. When the control unit 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 abnormal detection operation of the opening / closing devices shown in FIGS. 6 and 7 (step ST106). When the abnormal detection operation of the opening / closing devices is completed, the control unit 100 returns to step ST101 and executes the process of step ST101.

[0081] In FIGS. 6 and 7, the abnormality detection operation of the opening / closing device is executed for each of the indoor units 30a, 30b, and 30c. In the present embodiment, the flowcharts of the abnormality detection operation of the opening / closing device shown in FIGS. 6 and 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 / closing device corresponds to an example of the abnormality determination control of the opening / closing device. As shown in FIG. 6, when the control unit 100 starts the process of the abnormality detection operation of the opening / closing device, it determines whether it is in the cooling operation mode (step ST110). Thereby, the flow directions F1 and F2 of the refrigerant are determined, and it is determined which of the first opening / closing device 101 and the second opening / closing device 102 is upstream in the flow direction of the refrigerant.

[0082] When the control unit 100 determines that it is in 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, by setting the second opening / closing device 102 on the downstream side to the closed state, the impact on the second opening / closing device 102 in the closed state can be suppressed. The control unit 100 sets the first opening / closing device 101 corresponding to the upstream side to the open state and sets the second opening / closing device 102 corresponding to the downstream side to the closed state (step ST112). Thereby, when the second opening / closing device 102 functions normally, since the second opening / closing device 102 is in the closed state, the refrigerant is blocked. For this reason, the refrigerant stays in the indoor heat exchanger 301, and heat exchange is not performed in the indoor heat exchanger 301. Therefore, the temperature difference between the refrigerant in the liquid side pipe 13 on the upstream side of the indoor heat exchanger 301 and the refrigerant in the gas side pipe 14 on the downstream side becomes small.

[0083] The control unit 100 fully opens the indoor expansion valve 304 (step ST113). Thereby, when there is an abnormality in the second opening / closing device 102, it facilitates the flow of the refrigerant into the indoor heat exchanger 301. The control unit 100 determines whether or not the third predetermined time has elapsed (step ST114). The third predetermined time in step ST114 is set to be the time when the refrigerant staying in the indoor heat exchanger 301 stops exchanging heat with the indoor air. In the present embodiment, as an example of the third predetermined time, 4 minutes is set.

[0084] The control unit 100 determines whether the refrigerant temperature of the liquid-side pipe 13 of the indoor heat exchanger 301 and the refrigerant temperature of the gas-side pipe 14 are equal to or lower than a predetermined value (step ST115). In the present embodiment, a difference value between the detected temperature of the first temperature sensor 305 provided in the liquid-side pipe 13 and the detected temperature of the second temperature sensor 306 provided in the gas-side pipe 14 is calculated. Then, it is determined whether the difference value of the detected temperatures is equal to or lower than a minute predetermined value. Here, when the second opening / closing device 102 operates normally, the flow of the refrigerant is blocked and the refrigerant stays in the indoor heat exchanger 301. For this reason, 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 / 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 to occur in the indoor heat exchanger 301. For this reason, 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 there is an abnormality in the second opening / closing device 102, it is determined whether the refrigerant temperature of the liquid-side pipe 11 of the indoor heat exchanger 301 and the refrigerant temperature of the gas-side pipe 12 are equal to or lower than a predetermined value.

[0085] When the control unit 100 determines that the refrigerant temperature of the liquid-side pipe 13 of the indoor heat exchanger 301 and the refrigerant temperature of the gas-side pipe 14 are equal to or lower than a predetermined value (step ST115; YES), the first opening / closing device 101 corresponding to the upstream side is closed and the second opening / closing device 102 corresponding to the downstream side is opened (step ST116). The control unit 100 determines whether a third predetermined time has elapsed (step ST117). Step ST117 is the same as step ST114. The control unit 100 determines whether the refrigerant temperature of the liquid-side pipe 13 of the indoor heat exchanger 301 and the refrigerant temperature of the gas-side pipe 14 are equal to or lower than a predetermined value (step ST118). Step ST118 is the same as step ST115.

[0086] When the control unit 100 determines that the refrigerant temperature of the liquid side pipe 13 and the refrigerant temperature of the gas side pipe 14 of the indoor heat exchanger 301 are equal to or lower than a predetermined value (step ST118; YES), the control unit 100 opens the first opening / closing device 101 (step ST119). Thereby, the first opening / closing device 101 is returned to its original state. Then, the control unit 100 terminates the abnormality detection operation of the opening / closing device.

[0087] When the control unit 100 determines that the refrigerant temperature of the liquid side pipe 13 and the refrigerant temperature of the gas side pipe 14 of the indoor heat exchanger 301 are not equal to or lower than a predetermined value (step ST115; NO), the control unit 100 determines that there is an abnormality in the second opening / closing device 102 and notifies the abnormality of the second opening / closing device 102 (step ST122). As a means for notifying the abnormality of the second opening / closing device 102, it is possible to configure to display on the operation screen 100b that the second opening / closing device 102 is abnormal, or to control a sound source as an example of a notification means (not shown) to emit a notification sound. The control unit 100 fully closes the indoor expansion valve 304 (step ST121). Thereby, the flow of the refrigerant is blocked. Then, the control unit 100 terminates the abnormality detection operation of the opening / closing device.

[0088] When the control unit 100 determines that the refrigerant temperature of the liquid side pipe 13 and the refrigerant temperature of the gas side pipe 14 of the indoor heat exchanger 301 are not equal to or lower than a predetermined value (step ST118; NO), the control unit 100 determines that there is an abnormality in the first opening / closing device 101 and notifies the abnormality of the first opening / closing device 101 (step ST120). The control unit 100 fully closes the indoor expansion valve 304 (step ST121) and terminates the abnormality detection operation of the opening / closing device.

[0089] When the control unit 100 is not in the cooling operation mode, that is, in the heating operation mode (step ST110; NO), the control unit 100 controls the indoor expansion valve 304 to close and throttle it (step ST130 in FIG. 7). By throttling the indoor expansion valve 304, the refrigerant flow rate is reduced. 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 opposite to the opening / closing devices in steps ST112 to ST121 shown in FIG. 6. Therefore, detailed description thereof will be omitted.

[0090] Here, in the conventional configuration described in Patent Document 1, unless refrigerant leakage occurs, the opening / closing device is not set to the closed state. Therefore, there is a case where fixation occurs in the opening / closing device, etc., and there is a problem that the reliability of the opening / closing device is reduced.

[0091] On the other hand, in the present embodiment, by the processes of steps ST112 to ST115, steps ST116 to ST118, steps ST131 to ST134, and steps ST135 to ST137, when the opening / closing devices 101 and 102 are in the closed state, it is normally determined whether or not the refrigerant is blocked. Therefore, when the opening / closing devices 101 and 102 are determined to be abnormal, the opening / closing devices 101 and 102 can be repaired or replaced, so that the reliability of the opening / closing devices 101 and 102 is improved.

[0092] As described above, the air conditioner 1 of the present embodiment includes an outdoor unit 20 having a compressor 201, an indoor unit 30 having an indoor heat exchanger 301, liquid side pipes 11 and 13 and gas side pipes 12 and 14 connecting the outdoor unit 20 and the indoor unit 30, a first opening / closing device 101 that opens and closes the liquid side pipe 13 connected to the indoor unit 30, a second opening / closing device 102 that opens and closes the gas side pipe 13 connected to the indoor unit 30, an indoor expansion valve 304 provided between the first opening / closing device 101 and the indoor heat exchanger 301 to control the refrigerant flow rate, and a control unit 100. In this air conditioner 1, the control unit 100 performs an abnormality detection operation of closing at least one of the first opening / closing device 101 and the second opening / closing device 102 with the indoor expansion valve 304 open, and determining an abnormal state of the opening / closing device 101 or 102 that has been closed among the first opening / closing device 101 and the second opening / closing device 102. Thereby, the abnormal state of the first opening / closing device 101 and the second opening / closing device 102 can be determined based on whether or not the refrigerant flowing in the indoor unit 30 is blocked by the closed opening / closing devices 101 and 102.

[0093] In this embodiment, the air conditioner 1 includes a first temperature sensor 305 that is disposed in the liquid-side pipe 13 between the first opening / closing device 101 and the indoor heat exchanger 301 and detects the refrigerant temperature, and a second temperature sensor 306 that is disposed in the gas-side pipe 14 between the second opening / closing device 102 and the indoor heat exchanger 301 and detects the refrigerant temperature. Then, in the abnormality detection operation, the control unit 100 of the air conditioner 1 performs open control on one of the first opening / closing device 101 and the second opening / closing device 102, i.e., the opening / closing device 101 or 102, and performs close control on the other opening / closing device 102 or 101, and determines that the other opening / closing device 102 or 101 is in an abnormal state when the difference value between the detected temperatures of the first temperature sensor 305 and the second temperature sensor 306 is higher than a predetermined temperature. Thereby, the refrigerant temperature between the first opening / closing device 101 and the indoor heat exchanger 301 and the refrigerant temperature between the second opening / closing device 102 and the indoor heat exchanger 301 can be detected. For this reason, based on the temperature difference between the liquid side and the gas side of the indoor heat exchanger 301, it can be determined whether the refrigerant is blocked, and the abnormal state of the opening / closing devices 101 and 102 can be determined.

[0094] Also, in this embodiment, in the abnormality detection operation, the control unit 100 throttles the indoor expansion valve 304, performs open control on the opening / closing device 101 or 102 on the upstream side in the refrigerant flow direction among the first opening / closing device 101 and the second opening / closing device 102, and performs close control on the opening / closing device 102 or 101 on the downstream side, and determines whether the opening / closing device 102 or 101 on the downstream side is in an abnormal state. Thereby, since the indoor expansion valve 304 reduces the refrigerant flow rate flowing to the opening / closing devices 102 and 101 on the downstream side in the refrigerant flow direction and performs close control on the opening / closing devices 102 and 101 on the downstream side in the refrigerant flow direction, the impact received by the opening / closing devices 102 and 101 from the refrigerant can be suppressed.

[0095] Also, in this embodiment, in the abnormality detection operation, after determining whether the opening / closing device 102 or 101 on the downstream side is in an abnormal state, the control unit 100 performs open control on the opening / closing device 102 or 101 on the downstream side and performs close control on the opening / closing device 101 or 102 on the upstream side, and determines whether the opening / closing device 101 or 102 on the upstream side is in an abnormal state. This makes it possible to also determine abnormalities in the opening / closing devices 102 and 101 on the upstream side in the refrigerant flow direction.

[0096] Further, in the present embodiment, when the control unit 100 determines that the opening / closing devices 101 and 102 are in an abnormal state during the abnormality detection operation, the control unit 100 notifies that the opening / closing devices 101 and 102 are in an abnormal state. This makes it easier to recognize that the opening / closing devices 101 and 102 are in an abnormal state.

[0097] Further, in the present embodiment, when the control unit 100 determines that at least one of the first opening / closing device 101 and the second opening / closing device 102 is in an abnormal state during the abnormality detection operation, the control unit 100 performs closing control on the indoor expansion valve 304. This makes it possible to perform closing control on the indoor expansion valve 304 to regulate the refrigerant flow when the opening / closing devices 101 and 102 are in an abnormal state.

[0098] Further, in the present embodiment, when the operating frequency of the compressor 201 is equal to or lower than a predetermined value and the second predetermined time has elapsed after the abnormality detection operation is performed, the control unit 100 performs the abnormality detection operation again. This makes it possible to open and close the opening / closing devices 101 and 102 to perform the abnormality detection operation when the impact received from the refrigerant flow is small. Further, it is possible to suppress the execution of excessive abnormality detection operations.

[0099] FIG. 8 is a flowchart showing a refrigerant leakage detection operation of the air conditioner 1 according to the first embodiment. The operation in FIG. 8 is executed by the control unit 100 controlling each part of the air conditioner 1. As shown in FIG. 8, when starting the process of the refrigerant leakage detection operation, the control unit 100 determines whether or not refrigerant leakage has been detected based on the detection result of the refrigerant leakage sensor 307 (step ST201).

[0100] When the control unit 100 does not detect refrigerant leakage (step ST201; NO), the control unit 100 executes the process of step ST201. When the control unit 100 detects refrigerant leakage (step ST201; YES), it continues the operation of the indoor fan 302 (step ST202). As a result, the refrigerant leaked into the room is conveyed by the blowing of the indoor fan 302, and the refrigerant leaked into the room becomes easier to be diluted.

[0101] The control unit 100 controls the operating frequency of the compressor 201 to decrease (step ST203). The control of decreasing the operating frequency is performed, for example, as follows. It is performed so as to be a value obtained by multiplying the operating frequency of the compressor 201 before detection by the ratio of the operating capacity of the indoor unit 30 in which leakage is detected to the operating capacity of all the indoor units 30. Specifically, for example, when the operating frequency before detection is 60 Hz, the operating capacity of the indoor unit 30 in which leakage is detected is 5 HP (horsepower), and the operating capacity of all the indoor units 30 is 15 HP, the control of decreasing the operating frequency is performed so that 60 Hz × (5 HP / 15 HP) = 20 Hz.

[0102] The control unit 100 fully closes the indoor expansion valve 304 in the indoor unit 30 in which leakage is detected (step ST204). Thereby, the flow of the refrigerant can be regulated. The control unit 100 closes the first on-off device 101 and the second on-off device 102 corresponding to the indoor unit 30 in which leakage is detected (step ST205). The control unit 100 determines whether or not the first on-off device 101 and the second on-off device 102 corresponding to the indoor unit 30 in which no leakage is detected are in the open state (step ST206).

[0103] When the first on-off device 101 and the second on-off device 102 corresponding to the indoor unit 30 in which no leakage is detected are in the open state (step ST206; YES), the control unit 100 continues the operation (step ST207) and ends the process of the refrigerant leakage detection operation. When the first on-off device 101 and the second on-off device 102 corresponding to the indoor unit 30 in which no leakage is detected are not in the open state (step ST206; NO), the control unit 100 stops the operation (step ST208) and ends the process of the refrigerant leakage detection operation.

[0104] Here, in the conventional configuration described in Patent Document 1, when refrigerant leakage occurs, the opening / closing device is set to the closed state. However, when refrigerant leakage occurs, simply setting the opening / closing device to the closed state alone may cause the impact of the refrigerant flowing in the refrigerant circuit to be transmitted to the closed opening / closing device, resulting in the risk of damage to the opening / closing device. Therefore, in the conventional configuration, there is a problem that the operation reliability of the opening / closing device decreases.

[0105] On the other hand, in the present embodiment, in step ST203, the driving frequency is reduced to decrease the refrigerant flow rate, and further in step ST204, the indoor expansion valve 304 is closed to regulate the refrigerant flow, and then in step ST205, the first opening / closing device 101 and the second opening / closing device 102 are set to the closed state. For this reason, it is possible to prevent the impact of the refrigerant flowing in the refrigerant circuit from being transmitted to the closed opening / closing devices 101 and 102. Therefore, the risk of damage to the opening / closing devices 101 and 102 can be reduced, and the operation reliability of the opening / closing devices 101 and 102 can be improved.

[0106] Although it is desirable to have the above-mentioned step ST204, it may be omitted. That is, the control unit 100 may shift to step ST205 after executing step ST203.

[0107] As described above, the air conditioner 1 of the present embodiment includes an outdoor unit 20 having a compressor 201, an indoor unit 30, refrigerant pipes 11, 12, 13, 14 connecting the outdoor unit 20 and the indoor unit 30, opening / closing devices 101, 102 for opening and closing the refrigerant pipes 13, 14, a refrigerant leakage sensor 307 for detecting the refrigerant concentration, and a control unit 100. Then, when the detected concentration of the refrigerant leakage sensor 307 is equal to or higher than a predetermined value, the control unit 100 controls the operating frequency of the compressor 201 to be equal to or lower than a predetermined value, and then sets the opening / closing devices 101, 102 to the closed state. As a result, after refrigerant leakage is detected, the operating frequency of the compressor 201 is decreased, and the opening / closing devices 101 and 102 are closed while the flow rate of the refrigerant flowing through the refrigerant circuit is low, so that the impact of the refrigerant transmitted to the opening / closing devices 101 and 102 is suppressed. For this reason, the risk of damage to the opening / closing devices 101 and 102 can be reduced, and the operation reliability of the opening / closing devices 101 and 102 can be improved.

[0108] In the present embodiment, when the detection concentration of the refrigerant leakage sensor 307 is equal to or higher than a predetermined value, the control unit 100 closes the indoor expansion valve 304 and then sets the opening / closing devices 101 and 102 to the closed state. As a result, after refrigerant leakage is detected, the indoor expansion valve 304 is closed and the opening / closing devices 101 and 102 are closed while the flow rate of the refrigerant flowing through the refrigerant circuit is low, so that the impact of the refrigerant transmitted to the opening / closing devices is suppressed. For this reason, the risk of damage to the opening / closing devices 101 and 102 can be reduced, and the operation reliability of the opening / closing devices 101 and 102 can be improved.

[0109] [2. Second Embodiment] FIG. 9 is a flowchart showing the transition determination operation for preventing sticking of the air conditioner 1 according to the second embodiment. In the second embodiment, the same reference numerals are given to the components common to the first embodiment, and the description thereof is omitted. The control unit 100 of the air conditioner 1 according to the second embodiment is different from the first embodiment in that, instead of the control of the flowchart shown in FIG. 3, the control of the flowchart shown in FIG. 9 is performed. As shown in FIG. 9, when starting the process of the transition determination operation for preventing sticking, the control unit 100 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 flow rate of the refrigerant is low and the flow of the refrigerant hardly impacts the opening / closing devices 101 and 102.

[0110] When the control unit 100 determines that the operating frequency of the compressor 201 is not equal to or lower than the predetermined value (step ST61; NO), the process of step ST61 is executed. When the control unit 100 determines that the operating frequency of the compressor 201 is equal to or lower than a predetermined value (step ST61; YES), at step ST62, it executes the sticking prevention operation shown in FIG. 4 and returns to step ST61.

[0111] In the present 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. Thereby, it becomes easier to open and close the opening / closing devices 101 and 102 in a state where the refrigerant flow rate is small, and the opening / closing devices 101 and 102 are less likely to be impacted by the refrigerant flow.

[0112] [3. Third Embodiment] FIG. 10 is a flowchart showing the transition determination operation for preventing sticking of the air conditioner 1 according to the third embodiment. In the third embodiment, components common to the first and second embodiments are denoted by the same reference numerals and the description thereof is omitted. The operation unit 100a of the air conditioner 1 according to the third embodiment is configured to input to the control unit 100 permission to transition to the sticking prevention operation. The operation unit 100a corresponds to an example of an input unit.

[0113] The control unit 100 of the air conditioner 1 according to the third embodiment is different from the first embodiment in that, instead of the control of the flowchart shown in FIG. 3, it performs the control of the flowchart shown in FIG. 10. As shown in FIG. 10, the control unit 100 detects the presence or absence of an input from the operation unit 100a and determines whether there is an input for the sticking prevention operation (step ST71).

[0114] When the control unit 100 does not detect an input for the sticking prevention operation (step ST71; NO), it executes the process of step ST71. When the control unit 100 detects an input for the sticking prevention operation (step ST71; YES), at step ST72, it executes the sticking prevention operation shown in FIG. 4 and returns to step ST71.

[0115] In the present embodiment, an operation unit 100a for inputting permission to shift to the sticking prevention operation is provided, and when the control unit 100 detects the input by the operation unit 100a, the control unit 100 executes the sticking prevention operation. Thereby, permission to shift to the sticking prevention operation can be input to the control unit 100. Therefore, the control unit 100 can be permitted to shift to the sticking prevention operation at an arbitrary timing.

[0116] [4. Fourth Embodiment] FIG. 11 is a flowchart showing the transition determination operation of abnormality detection of the air conditioner 1 according to the fourth embodiment. In the fourth embodiment, the same reference numerals are given to the constituent parts common to the first to third embodiments, and the description thereof is omitted. The operation unit 100a of the air conditioner 1 according to the fourth embodiment is configured to input permission to shift to the abnormality detection operation of the opening / closing device to the control unit 100. The operation unit 100a corresponds to an example of the second input unit.

[0117] The control unit 100 of the air conditioner 1 according to the fourth embodiment is different from the first embodiment in that, instead of the control of the flowchart shown in FIG. 5, the control of the flowchart shown in FIG. 11 is performed. As shown in FIG. 11, the control unit 100 detects the presence or absence of the input of the operation unit 100a and determines whether there is an input of permission to shift to the abnormality detection operation of the opening / closing device (step ST181).

[0118] When the control unit 100 does not detect the input of permission to shift to the abnormality detection operation of the opening / closing device (step ST181; NO), the control unit 100 executes the process of step ST181. When the control unit 100 detects the input of permission to shift to the abnormality detection operation of the opening / closing device (step ST181; YES), in step ST182, the control unit 100 executes the abnormality detection operation of the opening / closing device shown in FIGS. 6 and 7, and returns to step ST181.

[0119] In the present embodiment, an operation unit 100a for inputting permission to shift to the abnormality detection operation of the opening / closing device is provided, and when the control unit 100 detects the input by the operation unit 100a, the control unit 100 executes the abnormality detection operation of the opening / closing device. As a result, the control unit 100 can be permitted to shift to the abnormality detection operation of the opening / closing device at an arbitrary timing.

[0120] [5. Other Embodiments] Although the present invention has been described based on the embodiments, the present invention is not limited to these embodiments. Since it merely illustrates one embodiment of the present invention, it can be arbitrarily changed and applied without departing from the gist of the present invention.

[0121] The sticking prevention operation has been described as being executed based on the first predetermined time in the first embodiment, based on the operating frequency of the compressor 201 in the second embodiment, and based on the input of the operation unit 100a in the third embodiment. However, for example, the sticking prevention operation may be configured to be executed based on the first predetermined time and also based on the operating frequency of the compressor 201. Further, for example, the sticking prevention operation may be configured to be executed based on the operating frequency of the compressor 201 and also based on the input of the operation unit 100a. That is, the flowcharts shown in FIG. 3 of the first embodiment, FIG. 9 of the second embodiment, and FIG. 10 of the third embodiment are not limited to the configuration in which the control unit 100 processes them separately, and may be a configuration in which the control unit 100 processes them in parallel.

[0122] The abnormality detection operation of the opening / closing device has been described as being executed based on the second predetermined time and the operating frequency of the compressor 201 in the first to third embodiments, and based on the input of the operation unit 100a in the fourth embodiment. However, the abnormality detection operation of the opening / closing device may be configured to be executed based on the second predetermined time and the operating frequency of the compressor 201 and also based on the input of the operation unit 100a. That is, the flowcharts shown in FIG. 5 of the first to third embodiments and FIG. 11 of the fourth embodiment are not limited to the configuration in which the control unit 100 processes them separately, and may be a configuration in which the control unit 100 processes them in parallel.

[0123] In the above-described embodiment, as an example, an air conditioner 1 having a configuration of a package air conditioner (PAC) including one outdoor unit 20 and three indoor units 30 was shown, but the present invention is not limited thereto. For example, it is also applicable to a room air conditioner (RAC) including one outdoor unit 20 and one indoor unit 30, a package air conditioner (PAC) in which a plurality of indoor units are connected to a plurality of outdoor units, or a configuration of a multi-air conditioner (VRF) for a building.

Industrial Applicability

[0124] 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 refrigerant leaking even when refrigerant leakage occurs.

Explanation of Signs

[0125] 1 Air conditioner 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 units 100 Control unit 100a Operation unit (input unit, second input unit) 101a, 101b, 101c First opening / closing device 102a, 102b, 102c Second opening / closing device 201 Compressor 301a, 301b, 301c Indoor heat exchanger (utilization-side heat exchanger) 302a, 302b, 302c Indoor fans 304a, 304b, 304b Indoor expansion valves (throttling devices) 305a, 305b, 305c First temperature sensors 306a, 306b, 306c Second temperature sensors 307a, 307b, 307c Refrigerant leakage sensors

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 / closing device disposed in the refrigerant pipe, A control unit, In an air conditioner comprising: A throttle device for controlling the refrigerant flow rate between the opening / closing device and the utilization-side heat exchanger is provided, When there is no refrigerant leakage, the control unit executes a sticking prevention operation for opening and closing the opening / closing device, When the compressor is operating and there is an indoor unit that is stopped, the control unit controls the throttle device of the stopped indoor unit to open and controls the throttle device of the operating indoor unit to close, and executes the sticking prevention operation for the opening / closing device of the operating indoor unit. An air conditioner characterized by the above.

2. The refrigerant pipe has a liquid-side pipe and a gas-side pipe, The opening / closing device has a first opening / closing device for opening and closing the liquid-side pipe connected to the indoor unit and a second opening / closing device for opening and closing the gas-side pipe connected to the indoor unit. The air conditioner according to claim 1, characterized by the above.

3. The control unit executes the sticking prevention operation for opening and closing the first opening / closing device and the second opening / closing device. The air conditioner according to claim 2, characterized by the above.

4. The throttle device is provided in the liquid-side pipe. The air conditioner according to claim 2 or 3, characterized by the above.

5. Comprising a plurality of the indoor units arranged in parallel, For each of the indoor units, the first opening / closing device and the second opening / closing device are provided, For each of the indoor units, the throttle device is provided. The air conditioner according to any one of claims 2 to 4, characterized by the above.

6. When the control unit executes the sticking prevention operation and the compressor is stopped, the control unit executes the sticking prevention operation for the opening / closing devices of all the indoor units. The air conditioner according to claim 5, characterized by the above.

7. When the control unit executes the sticking prevention operation and the compressor is operating and there are a plurality of operating indoor units, the control unit controls the throttle device of the first operating indoor unit to close, executes the sticking prevention operation for the opening / closing device of the first operating indoor unit, then controls the throttle device of the second operating indoor unit to close, and executes the sticking prevention operation for the opening / closing device of the second operating indoor unit. The air conditioner according to claim 5 or 6, characterized by the above.

8. When the control unit executes the anti-seizure operation, the anti-seizure operation is executed for the opening / closing device of the indoor unit during the operation stop. The air conditioner according to any one of claims 1 to 7, characterized in that.

9. After a first predetermined time has elapsed since the control unit executes the anti-seizure operation, the anti-seizure operation is executed again. The air conditioner according to any one of claims 1 to 8, characterized in that.

10. The control unit executes the anti-seizure operation when the operating frequency of the compressor is equal to or lower than a predetermined value. The air conditioner according to any one of claims 1 to 9, characterized in that.

11. An input unit for inputting permission to shift to the anti-seizure operation is provided, When the control unit detects an input by the input unit, the control unit executes the anti-seizure operation. The air conditioner according to any one of claims 1 to 10, characterized in that.

12. In a state where the throttle device is open, the control unit controls at least one of the first opening / closing device and the second opening / closing device to be closed, and executes an abnormality determination control for determining an abnormal state of the opening / closing device that is closed among the first opening / closing device and the second opening / closing device. The air conditioner according to claim 4 or 5, characterized in that.

13. A first temperature sensor for detecting the refrigerant temperature disposed in the liquid side pipe between the first opening / closing device and the utilization side heat exchanger, A second temperature sensor for detecting the refrigerant temperature disposed in the gas side pipe between the second opening / closing device and the utilization side heat exchanger, and In the abnormality determination control, the control unit controls one of the first opening / closing device and the second opening / closing device to be open and the other opening / closing device to be closed, and determines that the other opening / closing device is in an abnormal state when a difference value between the detected temperatures of the first temperature sensor and the second temperature sensor is higher than a predetermined temperature. The air conditioner according to claim 12, characterized in that.

14. In the abnormality determination control, the control unit throttles the throttle device, controls the opening / closing device on the upstream side in the refrigerant flow direction among the first opening / closing device and the second opening / closing device to be open, and controls the opening / closing device on the downstream side to be closed, and determines whether the opening / closing device on the downstream side is in an abnormal state. The air conditioner according to claim 13, characterized in that.

15. After determining whether or not the downstream-side opening / closing device is in an abnormal state in the abnormality determination control, the control unit controls the downstream-side opening / closing device to open and controls the upstream-side opening / closing device to close, and determines whether or not the upstream-side opening / closing device is in an abnormal state. The air conditioner according to claim 14, characterized in that.

16. When the control unit determines that the opening / closing device is in an abnormal state in the abnormality determination control, the control unit notifies that the opening / closing device is in an abnormal state. The air conditioner according to any one of claims 12 to 15, characterized in that.

17. When the operating frequency of the compressor is equal to or lower than a predetermined value, and when a second predetermined time has elapsed after the abnormality determination control is executed, the control unit executes the abnormality determination control again. The air conditioner according to any one of claims 12 to 16, characterized in that.

18. It includes a second input unit for inputting permission to shift to the abnormality determination control. When the control unit detects an input by the second input unit, the control unit executes the abnormality determination control. The air conditioner according to any one of claims 12 to 17, characterized in that.

19. When the control unit determines that at least one of the first opening / closing device and the second opening / closing device is in an abnormal state in the abnormality determination control, the control unit controls the throttle device to close. The air conditioner according to any one of claims 12 to 18, characterized in that.

20. The indoor unit includes a refrigerant leakage sensor for detecting the refrigerant concentration. When the detected concentration of the refrigerant leakage sensor is equal to or higher than a predetermined value, the control unit controls the operating frequency of the compressor to be equal to or lower than a predetermined value, and then sets the opening / closing device to a closed state. The air conditioner according to claim 4 or 5, characterized in that.

21. When the detected concentration of the refrigerant leakage sensor is equal to or higher than a predetermined value, the control unit controls the throttle device to close, and then sets the opening / closing device to a closed state. The air conditioner according to claim 20, characterized in that.

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