Air conditioner

Abstract

Provided is an air conditioner capable of increasing the accuracy of determining that an operation valve is closed. An air conditioner 100 is provided with: a plurality of indoor units A, B that comprise indoor heat exchangers 4a, 4b; an outdoor unit C that comprises a compressor 1; a plurality of operation valves 3a–6b that open and close flow of a refrigerant through the plurality of indoor units A, B and the outdoor unit C; a rotational rate detection part 14 that detects the rotational rate of the compressor 1; a temperature difference detection part 15 that detects temperature differences between the temperatures of the indoor heat exchangers 4a, 4b and the temperatures of rooms in which the indoor heat exchangers are installed; and a determination part 16 that determines that an operation valve is closed if the rotational rate detected by the rotational rate detection part 14 is equal to or greater than a standard value and the temperature difference detected by the temperature difference detection part 15 is less than a closure assessment value. The standard value is a threshold value for a rated rotational rate of the compressor 1 determined in accordance with the total capacity of the indoor units that are running.

Description

air conditioner

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

[0002] Conventionally, air conditioners have been known that have a function for test-running the air conditioner after installation work is completed to determine whether the operating valve is closed and to inform the installation worker whether there have been any construction errors.

[0003] Patent Document 1 discloses an air conditioner that is equipped with a liquid pipe temperature sensor that detects the temperature of a liquid pipe connected to an indoor heat exchanger, and a gas pipe temperature sensor that detects the temperature of a gas pipe connected to the indoor heat exchanger, and that calculates the difference in temperatures detected by the liquid pipe temperature sensor and the gas pipe temperature sensor to determine the open / closed state of an operating valve provided in a connecting pipe that connects an outdoor unit and an indoor unit.

[0004] In the case of a multi-unit air conditioner with multiple indoor units connected to one outdoor unit, operating the air conditioner with the control valve closed can result in high pressure on the gas pipe and low pressure on the liquid pipe, for example, during heating operation. The temperature of the liquid pipe, where refrigerant accumulates, drops significantly, while the temperature change in areas where refrigerant is not accumulated is small. This can lead to variations in the detected temperature depending on the installation location of the liquid pipe temperature sensor, potentially leading to incorrect determination of the closed state of the control valve. Therefore, there is a need for improved accuracy in determining the closed state of the control valve.

[0005] JP 2011-149622 A

[0006] An object of the present disclosure is to provide an air conditioner that can improve the accuracy of determining whether an operating valve is in a closed state.

[0007] The air conditioner of the present disclosure comprises: a plurality of indoor units each having an indoor heat exchanger; an outdoor unit each having a compressor; a plurality of operating valves that open and close the flow of refrigerant between the plurality of indoor units and the outdoor unit; a rotation speed detection unit that detects the rotation speed of the compressor; a temperature difference detection unit that detects the temperature difference between the temperature of the indoor heat exchanger and the temperature of the room in which it is installed; and a judgment unit that judges that the operating valve is in a closed state when the rotation speed detected by the rotation speed detection unit is equal to or greater than a reference value and the temperature difference detected by the temperature difference detection unit is smaller than a close judgment value, wherein the reference value is a threshold value for the rated rotation speed of the compressor that is determined by the total capacity of the indoor units that are operating.

[0008] Refrigerant circuit configuration diagram of an air conditioner according to one embodiment. Control block diagram of the air conditioner according to the same embodiment. Graph showing the relationship between the total capacity of the indoor units and the reference value. Flowchart diagram showing an example of state determination of the control valve by the determination unit. Flowchart diagram showing another example of state determination of the control valve by the determination unit.

[0009] An embodiment of an air conditioner 100 will be described with reference to Figures 1 to 5. Note that in each figure, the dimensional ratios shown in the drawing do not necessarily match the actual dimensional ratios. Furthermore, the dimensional ratios between the drawings do not necessarily match. Figure 1 is a refrigerant circuit configuration diagram of the air conditioner 100 according to one embodiment.

[0010] As shown in Fig. 1, the air conditioner 100 is a multi-type air conditioner. The air conditioner 100 is equipped with multiple indoor units A and B and an outdoor unit C. In Fig. 1, two indoor units A and B are provided for one outdoor unit C, but this is not limited to this. For example, three or more indoor units may be provided for one outdoor unit C. The indoor unit A may be installed in the same room as the other indoor unit B, or in a different room from the other indoor unit B.

[0011] The air conditioner 100 includes gas side pipes 10a and 10b and liquid side pipes 11a and 11b. The refrigerant circuit of the air conditioner 100 includes a gas side control valve 3a connected to the gas side pipe 10a, a gas side control valve 3b connected to the gas side pipe 10b, a liquid side control valve 6a connected to the liquid side pipe 11a, and a liquid side control valve 6b connected to the liquid side pipe 11b.

[0012] The operating valves 3a to 6b (also referred to as "service valves 3a to 6b") open and close the flow of refrigerant between the indoor units A, B and the outdoor unit C. The operating valves 3a to 6b are manually operated valves that are used in the closed state when installing the air conditioner 100, for operational inspections, maintenance, etc., and are normally used in the open state after installation.

[0013] Because the configurations of indoor units A and B are all the same, the following description will only cover the configuration of indoor unit A, and will omit the description of indoor unit B. In addition, in Figure 1, the configuration of indoor unit B corresponding to the components of indoor unit A is obtained by changing the suffix of the number assigned to the components of indoor unit A from a to b.

[0014] The indoor unit A includes an indoor heat exchanger 4a, an indoor fan 5a, an indoor heat exchanger temperature sensor 12a, and a room temperature sensor 13a. The indoor unit A may further include a humidity sensor 17a. The humidity sensor 17a may be provided inside the indoor unit A or outside the indoor unit A (for example, in the room where the indoor unit A is installed).

[0015] The volume of the indoor heat exchanger 4a is set appropriately depending on the user's desired capacity of the indoor unit A. The volume of the indoor heat exchanger 4a may be the same as or different from the volume of the other indoor heat exchangers 4b.

[0016] The indoor heat exchanger 4a includes a refrigerant pipe (not shown) through which a refrigerant flows and a plurality of fins for exchanging heat between the refrigerant flowing in the refrigerant pipe and the indoor air. The indoor fan 5a ventilates the indoor air through the fins of the indoor heat exchanger 4a to exchange heat and cool or heat the indoor air.

[0017] The indoor heat exchanger temperature sensor 12a measures the temperature of the indoor heat exchanger 4a. The indoor heat exchanger temperature sensor 12a is, for example, a thermistor, and is attached to the indoor heat exchanger 4a.

[0018] The indoor heat exchanger temperature sensor 12a is preferably installed (attached) to a heat transfer tube of the indoor heat exchanger 4a. The indoor heat exchanger temperature sensor 12a is installed, for example, at a folded portion of the heat transfer tube.

[0019] It is more preferable to install the indoor heat exchanger temperature sensor 12a in the middle of the heat transfer tube. This reduces the influence of superheating and subcooling compared to installing the indoor heat exchanger temperature sensor 12a at the inlet or outlet of the heat transfer tube, allowing for more stable temperature measurement of the indoor heat exchanger 4a. The middle of the heat transfer tube is the portion of the heat transfer tube located approximately halfway along its entire length.

[0020] The room temperature sensor 13a measures the temperature of the indoor air, specifically the temperature of the air on the intake side of the indoor heat exchanger 4a. The room temperature sensor 13a may be provided inside the indoor unit A or outside the indoor unit A (for example, in the room where the indoor unit A is installed). The room temperature sensor 13a may be the same as the indoor heat exchanger temperature sensor 12a, or may be different.

[0021] The outdoor unit C includes a compressor 1, a four-way valve 2, motor-operated expansion valves 7a and 7b, an outdoor heat exchanger 8, an outdoor fan 9, and an outdoor air temperature sensor 22. The compressor 1 includes a motor (not shown) whose rotation speed is variable.

[0022] The four-way valve 2 switches whether the gas refrigerant discharged from the compressor 1 is guided to the outdoor heat exchanger 8 or to the indoor units A and B. That is, the four-way valve 2 switches between cooling operation and heating operation. The solid line in Fig. 1 indicates the state in which the four-way valve 2 is in heating operation, and the dashed line in Fig. 1 indicates the state in which the four-way valve 2 is in cooling operation.

[0023] The electric expansion valve 7a is provided in the liquid side pipe 11a, and the electric expansion valve 7b is provided in the liquid side pipe 11b. In this refrigerant circuit, the gas side operating valve 3a, the indoor heat exchanger 4a, the liquid side operating valve 6a, and the electric expansion valve 7a are connected in series, and the gas side operating valve 3b, the indoor heat exchanger 4b, the liquid side operating valve 6b, and the electric expansion valve 7b are connected in series, and both series refrigerant circuits are connected in parallel.

[0024] The outdoor heat exchanger 8 includes a refrigerant pipe (not shown) through which the refrigerant flows, and a plurality of fins for exchanging heat between the refrigerant flowing through the refrigerant pipe and outdoor air (outdoor air). The outdoor fan 9 blows outdoor air through the outdoor heat exchanger 8 (between the fins) to exchange heat and cool or heat the refrigerant.

[0025] The outdoor air temperature sensor 22 measures the outdoor temperature. The outdoor air temperature sensor 22 may be provided inside the outdoor unit C or outside the outdoor unit C. The outdoor air temperature sensor 22 may be the same as the indoor heat exchanger temperature sensor 12a or the room temperature sensor 13a, or may be different from them.

[0026] The operation during heating operation will be described with reference to Fig. 1. The solid arrows in Fig. 1 indicate the flow of refrigerant when the indoor units A and B are in heating operation.

[0027] The refrigerant compressed by the compressor 1 flows as a high-temperature, high-pressure gas refrigerant through the four-way valve 2 into each indoor heat exchanger 4a, 4b, where it dissipates heat to air blown by the indoor fans 5a, 5b, becoming a high-pressure liquid refrigerant. This allows heated air to flow into the room, providing indoor heating. The high-pressure liquid refrigerant then passes through each electric expansion valve 7a, 7b, where it is reduced in pressure, becoming a low-temperature, low-pressure, gas-liquid two-phase refrigerant. It then flows to the outdoor heat exchanger 8, where it absorbs heat from the air (outdoor air) blown by the outdoor fan 9, evaporating and becoming a gas refrigerant. This gas refrigerant returns to the compressor 1 through the four-way valve 2 and is compressed again. This is the refrigeration cycle during heating operation.

[0028] Next, the operation during cooling operation will be described with reference to Fig. 1. The dashed arrows in Fig. 1 indicate the flow of refrigerant when the indoor units A and B are operating in cooling mode.

[0029] The refrigerant compressed by the compressor 1 passes through the four-way valve 2 as a high-temperature, high-pressure gas refrigerant and flows into the outdoor heat exchanger 8. There, it condenses by releasing heat to the air (outdoor air) sent by the outdoor fan 9, becoming a high-pressure liquid refrigerant. The high-pressure liquid refrigerant then passes through each electric expansion valve 7a, 7b to be reduced in pressure, becoming a low-temperature, low-pressure gas-liquid two-phase refrigerant, and flows into the indoor heat exchangers 4a, 4b, where it evaporates by absorbing heat from the air sent by the indoor fans 5a, 5b, thereby achieving indoor cooling. The gas refrigerant evaporated in the indoor heat exchangers 4a, 4b returns to the compressor 1 via the four-way valve 2 and is compressed again. This is the refrigeration cycle during cooling operation.

[0030] When the air conditioner 100 is shipped from the factory, the outdoor unit C is separated from the indoor units A and B. The refrigerant is sealed in the refrigerant circuit on the outdoor unit C side, and the gas side operating valves 3a and 3b and the liquid side operating valves 6a and 6b are closed.

[0031] To install the air conditioner 100 in this factory-shipped state, first install the outdoor unit C and indoor units A and B in their designated locations, then connect the gas side piping 10a and liquid side piping 11a connected to indoor unit A to the gas side operating valve 3a and liquid side operating valve 6a, respectively. Then, operate the vacuum pump connected to the gas side operating valve 3a to create a vacuum, and then remove the vacuum pump. Then, fully open the liquid side operating valve 6a and the gas side operating valve 3a, allowing the refrigerant sealed in the refrigerant circuit of outdoor unit C to flow into the refrigerant circuit of indoor unit A, completing the installation of indoor unit A. Perform the same procedure for indoor unit B to complete the installation of the air conditioner 100.

[0032] In normal operation of the air conditioner 100 after this installation work is completed, the temperature difference between the operating temperature of the indoor heat exchanger 4a and the room temperature becomes large. However, if the air conditioner 100 is operated when both the gas-side operating valve 3a and the liquid-side operating valve 6a are closed due to an installation error, refrigerant does not circulate through the indoor heat exchanger 4a, and the temperature difference does not become as large as in normal operation. Furthermore, the compressor 1 may become overloaded, causing its temperature to rise abnormally, potentially damaging the compressor 1. Therefore, the following configuration is used to determine whether the operating valves 3a and 6a are closed (a similar determination can be made for the operating valves 3b and 6b).

[0033] The air conditioner 100 is equipped with a rotation speed detection unit 14 that detects the rotation speed of the compressor 1, a temperature difference detection unit 15 that detects the temperature difference between the temperature of the indoor heat exchangers 4a, 4b after they have started operating and the temperature (room temperature) of the room in which they are installed, and a judgment unit 16 that judges whether at least one of the operating valves 3a to 6b is in a closed state.

[0034] 2 is a control block diagram of the air conditioner 100. As shown in FIGS. 1 and 2, the rotation speed detection unit 14 detects the rotation speed of the motor of the compressor 1. The rotation speed detection unit 14 may directly detect the rotation speed of the motor using, for example, an encoder attached to the drive shaft of the motor, or may detect the rotation speed of the motor from the drive current supplied to the motor. In the present disclosure, the rotation speed of the compressor 1 refers to the rotation speed of the motor.

[0035] The temperature difference detection unit 15 detects the temperature difference between the temperature of the indoor heat exchanger 4a measured by the indoor heat exchanger temperature sensor 12a and the room temperature (room temperature) measured by the room temperature sensor 13a. The temperature difference detection unit 15 also detects the temperature difference between the temperature of the indoor heat exchanger 4b measured by the indoor heat exchanger temperature sensor 12b and the room temperature (room temperature) measured by the room temperature sensor 13b. In this embodiment, one temperature difference detection unit 15 is provided for each air conditioner 100, and one temperature difference detection unit 15 detects the temperature difference between each indoor unit A and B. However, this is not limited to this. For example, a temperature difference detection unit 15 may be provided for each indoor unit A and B, and the temperature difference between each indoor unit A and B may be detected by the temperature difference detection unit provided in each indoor unit A and B. The temperature difference is calculated, for example, by room temperature minus the temperature of the indoor heat exchanger during cooling operation, and by the temperature of the indoor heat exchanger minus room temperature during heating operation.

[0036] The determination unit 16 determines that the control valves 3a, 6a are closed when the rotation speed of the compressor 1 detected by the rotation speed detection unit 14 is equal to or greater than a reference value and the temperature difference detected by the temperature difference detection unit 15 is smaller than a close determination value. With this configuration, when the control valves 3a, 6a are closed, no refrigerant flows through the refrigerant circuit of the indoor unit A, so the closed state of the control valves 3a, 6a can be determined based on the temperature difference between the temperature of the indoor heat exchanger 4a after operation and the temperature of the room in which it is installed. By making this determination when the rotation speed of the compressor 1 after operation is equal to or greater than a reference value, the determination unit 16 can prevent erroneous determinations that the control valves 3a, 6a are closed. For example, if multiple indoor units A and B are operated when the rotation speed of the compressor 1 is lower than the reference value, the amount of refrigerant circulating through the refrigerant circuit of indoor unit A is small, so the temperature difference between the temperature of the indoor heat exchanger 4a and the room temperature becomes small. In other words, the temperature difference between the open and closed states of the operating valves 3a and 6a becomes small, making it difficult to determine the closed state of the operating valves 3a and 6a. This allows the determination unit 16 to improve the accuracy of determining the closed state of the operating valves 3a and 6a. The determination unit 16 also makes the same determination for the operating valves 3b and 6b (and the same applies below).

[0037] The close determination value (also referred to as the "close determination temperature difference") can be set appropriately depending on the combination of the indoor units A, B and the outdoor unit C. The close determination value is, for example, 5°C.

[0038] The reference value (also referred to as the "reference rotation speed") is a threshold value for the rotation speed of the compressor 1. Because the total capacity varies depending on the combination and number of indoor units, if the threshold value for the rotation speed of the compressor 1 is specified as an absolute value, for example, if the threshold value is too low, the control valves 3a and 6a may be erroneously determined to be closed even when they are actually open due to a lack of refrigerant circulation. Furthermore, if the threshold value for the rotation speed of the compressor 1 is too high, the rotation speed of the compressor 1 may not reach the reference value during operation, making it impossible to determine the state of the control valves 3a and 6a. Therefore, the threshold value for the rotation speed of the compressor 1 is set to a threshold value for the rated rotation speed of the compressor 1, which is determined by the total capacity (kW) of the operating indoor units A and B. The threshold value is, for example, 90% of the rated rotation speed of the compressor 1. The threshold value can also be set appropriately depending on the combination of the indoor units A and B and the outdoor unit C.

[0039] Figure 3 is a graph showing the relationship between the total capacity of indoor units A and B and the reference value. As shown in Figure 3, the reference value is proportional to the total capacity of the indoor units. In Figure 3, areas A1 to A6 are defined by the reference value, a judgment upper limit rotation speed, and a judgment lower limit rotation speed, which will be described later. In areas A1 to A3, the judgment unit judges that the compressor rotation speed is equal to or greater than the reference value. In areas A4 to A6, the judgment unit judges that the compressor rotation speed is less than the reference value.

[0040] FIG. 4 is a flowchart illustrating an example of the determination of the state of the control valve by the determination unit. As shown in FIG. 4, first, the compressor rotation speed is detected (S1). Then, it is determined whether the rotation speed is equal to or greater than a reference value (S2). If the rotation speed is equal to or greater than the reference value in S2, the temperature difference between the temperature of the indoor heat exchanger and the room temperature is detected (S3). Then, it is determined whether the temperature difference is smaller than a close determination value (S4). If the temperature difference is smaller than the close determination value in S4, the determination unit determines that the control valve is in a closed state (S5). If the temperature difference is equal to or greater than the close determination value in S4, it is determined whether the temperature difference is larger than a later-described open determination value (S6). Note that, although the flowchart in FIG. 4 first determines whether the rotation speed is equal to or greater than the reference value (S2), it is also possible to first determine whether the temperature difference is smaller than the close determination value (S4). That is, S3 and S4 may be performed before S1 and S2.

[0041] As shown in Figures 1 and 2, the determination unit 16 preferably determines that the control valves 3a, 6a are open when the temperature difference between the temperature of the indoor heat exchanger 4a (after operation) and the temperature (room temperature) of the room in which it is installed is greater than an open determination value (see S6 and S7 in Figure 4). With this configuration, by determining that the control valves 3a, 6a are open, it is possible to prevent the control valves 3a, 6a from being determined to be closed during subsequent operation of the air conditioner 100. This reduces erroneous determinations of the closed state of the control valves 3a, 6a and improves the accuracy of determining the open / closed states of the control valves 3a, 6a. The determination unit 16 does not necessarily have to determine whether the control valves 3a, 6a are open. The open determination value may be the same as or different from the closed determination value.

[0042] The determination unit 16 preferably determines the state of the control valves 3a, 6a when the rotation speed of the compressor 1 is equal to or higher than the determination upper limit rotation speed (areas A1, A4 in FIG. 3 ). According to this configuration, by determining that the compressor 1 is in the closed state when the rotation speed of the compressor 1 is equal to or higher than the determination upper limit rotation speed and then stopping the operation of the compressor 1, it is possible to prevent the discharge pressure of the compressor 1 from increasing and the compressor 1 from being overheated, thereby preventing damage to the compressor 1.

[0043] The upper limit rotation speed for determination is the rotation speed at which the discharge pressure of the compressor 1 increases and the compressor 1 becomes excessively heated. The upper limit rotation speed for determination can be set appropriately depending on the combination of the indoor units A, B and the outdoor unit C.

[0044] When the rotation speed of the compressor 1 is equal to or lower than the lower limit rotation speed (areas A3 and A6 in FIG. 3 ), it is preferable that the determination unit 16 does not determine whether the control valves 3a and 6a are in the closed state, even if the temperature difference detected by the temperature difference detection unit 15 is smaller than the close determination value. With this configuration, by determining whether the control valves 3a and 6a are in the closed state when the rotation speed exceeds the lower limit rotation speed, it is possible to avoid making a determination in a rotation speed range where damage to the compressor 1 will not occur. This allows the determination unit 16 to suppress erroneous determinations of the closed state of the control valves 3a and 6a. This is because when the rotation speed of the compressor 1 is equal to or lower than the lower limit rotation speed, the discharge pressure of the compressor 1 does not increase excessively and the compressor 1 is not overheated.

[0045] The lower limit rotation speed for determination is a rotation speed at which the discharge pressure of the compressor 1 does not increase and the compressor 1 does not become excessively heated. The lower limit rotation speed for determination can be set appropriately depending on the combination of the indoor units A, B and the outdoor unit C.

[0046] Fig. 5 is a flowchart showing another example of the determination of the state of the control valve by the determination unit. Differences from the flowchart of Fig. 4 will be described below. As shown in Fig. 5, if the rotation speed is less than the reference value in S2 and is equal to or greater than the upper limit rotation speed for determination (S7), the temperature difference between the temperature of the indoor heat exchanger and the room temperature is detected (S3). If the rotation speed is equal to or greater than the reference value in S2 and is equal to or less than the lower limit rotation speed for determination (S8), the determination unit does not determine the state of the control valve. If the rotation speed exceeds the lower limit rotation speed for determination in S9, the temperature difference between the temperature of the indoor heat exchanger and the room temperature is detected (S3).

[0047] As shown in Figures 1 and 2, the closure determination value may be set based on the room temperature and humidity during cooling operation. According to this configuration, by setting the closure determination value based on the room temperature and humidity, erroneous determination of the closed state of the control valves 3a and 6a can be suppressed. This is because, during cooling operation, humidity affects sensible heat and latent heat, so the difference between the heat exchanger temperature and the room temperature changes even with the same compressor rotation speed. This improves the accuracy of determining the state of the control valves 3a and 6a. The closure determination value may be set for each room in which each indoor unit A and B is installed. The same applies to the open determination value.

[0048] The room temperature is measured by the room temperature sensor 13a, and the humidity is measured by the humidity sensor 17a. When the room temperature and humidity are high and the temperature difference between the temperature of the indoor heat exchanger 4a and the room temperature is small, the determination unit 16 sets the close determination value lower than normal. For example, when the room temperature is 32°C or higher and the humidity is 80% or higher, the determination unit 16 sets the close determination value 2°C lower than normal.

[0049] The closure determination value may be set based on the room temperature and the outside air temperature. With this configuration, by setting the closure determination value based on the room temperature and the outside air temperature, it is possible to prevent erroneous determination of the closed state of the control valves 3a and 6a. This is because the refrigeration capacity changes depending on the room temperature and the outside air temperature, and the temperature difference between the temperature of the indoor heat exchanger 4a and the room temperature also changes. This improves the accuracy of determining the closed state of the control valves 3a and 6a.

[0050] The outdoor air temperature is measured by the outdoor air temperature sensor 22. For example, when the outdoor air temperature is low, the temperature difference between the temperature of the indoor heat exchanger 4a and the room temperature becomes large, so the determination unit 16 sets the close determination value higher than normal. For example, when the room temperature is 27°C or higher and the outdoor air temperature is 27°C or lower, the determination unit 16 sets the close determination value 2°C higher than normal. The same applies to the open determination value.

[0051] It is preferable that the determination unit 16 individually determine the state (whether the state is closed or open) of each of the multiple control valves 3 a to 6 b connected to the multiple indoor units A, B. According to this configuration, by determining the state of each of the control valves 3 a to 6 b, it becomes easy to identify the indoor unit to which an control valve that is in a closed state is connected.

[0052] During defrosting operation, it is preferable that the determination unit 16 does not determine the state of the control valves 3a and 6a even when the rotation speed detected by the rotation speed detection unit 14 is equal to or greater than the reference value and the temperature difference detected by the temperature difference detection unit 15 is smaller than the close determination value. With this configuration, by not determining the state of the control valves 3a and 6a during defrosting operation, which is subject to large fluctuations in the refrigerant state, erroneous determination of the closed state of the control valves 3a and 6a can be suppressed. This improves the accuracy of determining the closed state of the control valves 3a and 6a. The defrosting operation is an operation for removing frost that has formed on the outdoor heat exchanger 8 during heating operation.

[0053] As shown in Fig. 5, the determination unit first checks whether the defrost operation is in progress (S10). If a defrost operation signal is received in S10, the determination unit does not determine the state of the operation unit. If a defrost operation signal is not received in S10, the determination unit detects the compressor rotation speed (S1).

[0054] 1 and 2, the air conditioner 100 preferably includes a determination time measurement unit 18 that measures the time for which the state (closed state or open state) of the control valves 3a, 6a is determined, and a measurement time determination unit 19 that determines whether the time measured by the determination time measurement unit 18 exceeds the determination time. This configuration makes it possible to prevent erroneous determination of the state (closed state or open state) of the control valves 3a, 6a due to unintended noise, etc., thereby improving the accuracy of determining the state of the control valves 3a, 6a.

[0055] The determination time is set appropriately depending on the combination of the indoor units A, B and the outdoor unit C. The determination time is, for example, 0.5 to 5 minutes.

[0056] The air conditioner 100 preferably includes a notification unit 20 that notifies that the control valves 3a to 6b are in a closed state, and a compressor control unit 21 that stops operation of the compressor 1. When the measurement time determination unit 19 determines that the time measured by the determination time measurement unit 18 has exceeded the determination time, the notification unit 20 notifies that the control valves 3a to 6b are in a closed state, and the compressor control unit 21 stops operation of the compressor 1. With this configuration, by stopping operation of the compressor 1 when the control valves 3a to 6b are in a closed state, damage to the compressor 1 can be suppressed.

[0057] The notification unit 20 may have any configuration as long as it can notify the operator that the control valves 3a to 6b are in a closed state. For example, the notification unit 20 may be a lamp (not shown) provided in the indoor unit A, or a buzzer that emits a warning sound. If the notification unit 20 is a lamp, the notification unit 20 may blink the lamp or light the lamp. The notification unit 20 may also notify the operator of the error content via a terminal or the like of the operator.

[0058] The notification unit 20 is not limited to the above, and may issue a notification when the determination unit 16 determines that the control valves 3a to 6b are in the closed state. The compressor control unit 21 is not limited to the above, and may stop the operation of the compressor 1 when the determination unit 16 determines that the control valves 3a to 6b are in the closed state.

[0059] [1] As described above, in this embodiment, the air conditioner 100 includes a plurality of indoor units A, B each having indoor heat exchangers 4a, 4b, an outdoor unit C having a compressor 1, a plurality of control valves 3a to 6b that open and close the flow of refrigerant between the plurality of indoor units A, B and the outdoor unit C, a rotation speed detection unit 14 that detects the rotation speed of the compressor 1, a temperature difference detection unit 15 that detects the temperature difference between the temperatures of the indoor heat exchangers 4a, 4b and the temperature of the room in which they are installed, and a determination unit 16 that determines that the control valves 3a to 6b are in a closed state when the rotation speed detected by the rotation speed detection unit 14 is equal to or greater than a reference value and the temperature difference detected by the temperature difference detection unit 15 is smaller than a close determination value, where the reference value is a threshold value for the rated rotation speed of the compressor 1 that is determined by the total capacity of the indoor units A, B that are operating.

[0060] With this configuration, when the control valves are closed, no refrigerant flows through the refrigerant circuit of the indoor unit, so the closed state of the control valves 3a to 6b can be determined based on the temperature difference between the temperature of the indoor heat exchanger 4a after it has started operating and the room temperature where it is installed. By performing this determination when the rotation speed of the compressor 1 after it has started operating is equal to or greater than a reference value, the determination unit 16 can prevent erroneous determinations of the closed state of the control valves 3a to 6b. This allows the determination unit 16 to improve the accuracy of determining the closed state of the control valves 3a to 6b.

[0061] [2] In the air conditioner 100 described in [1] above, it is preferable that the determination unit 16 determines that the operating valve is in the open state when the temperature difference is greater than an open determination value.

[0062] With this configuration, by determining that the control valves are in the open state, it is possible to prevent the control valves 3a to 6b from being determined to be in the closed state during subsequent operation of the air conditioner 100. This prevents erroneous determinations that the control valves 3a to 6b are in the closed state, and improves the accuracy of determining the states of the control valves 3a to 6b.

[0063] [3] In the air conditioner 100 described in [1] or [2] above, it is preferable that the determination unit 16 determines the state of the operating valves 3a to 6b when the rotation speed of the compressor 1 is equal to or greater than a determination upper limit rotation speed.

[0064] According to this configuration, when the rotation speed of the compressor 1 is equal to or higher than the upper limit rotation speed, it is determined that the compressor is in the closed state, and then the operation of the compressor 1 is stopped, thereby preventing the discharge pressure of the compressor 1 from increasing and causing the compressor 1 to become overheated, and preventing damage to the compressor 1.

[0065] [4] In the air conditioner 100 described in any one of [1] to [3] above, it is preferable that the determination unit 16 does not determine whether the operating valves 3a to 6b are in a closed state when the rotation speed of the compressor 1 is equal to or lower than a determination lower limit rotation speed.

[0066] According to this configuration, by determining whether the control valves 3a to 6b are in the closed state when the rotation speed exceeds the determination lower limit, it is possible to avoid making a determination in a rotation speed range that will not cause damage to the compressor 1. This allows the determination unit 16 to suppress erroneous determinations that the control valves 3a to 6b are in the closed state.

[0067] [5] In addition, in the air conditioner 100 described in any one of [1] to [4] above, the closing judgment value may be configured to be set based on the temperature of the room and the humidity of the room during cooling operation.

[0068] With this configuration, by setting the close determination value based on the room temperature and humidity, it is possible to prevent erroneous determination of the closed state of the control valves 3a to 6b, thereby improving the accuracy of determining the closed state of the control valves 3a to 6b.

[0069] [6] In the air conditioner 100 described in any one of [1] to [4] above, the close determination value may be set based on the room temperature and the outside air temperature.

[0070] With this configuration, by setting the closure determination value based on the room temperature and the outside air temperature, it is possible to prevent erroneous determination of the closed state of the control valves 3 a to 6 b, thereby improving the accuracy of determining the closed state of the control valves 3 a to 6 b.

[0071] [7] In addition, in the air conditioner 100 described in any one of [1] to [6] above, it is preferable that the judgment unit 16 is configured to individually judge the state of each of the multiple control valves 3a to 6b connected to the multiple indoor units A and B.

[0072] According to this configuration, by determining the state of each of the control valves 3a to 6b, it becomes easy to identify the indoor unit to which the control valve in the closed state is connected.

[0073] [8] In addition, in the air conditioner 100 described in any one of [1] to [7] above, it is preferable that the determination unit 16 does not determine the state of the operating valves 3a to 6b during defrost operation.

[0074] With this configuration, the state of the control valves 3a and 6a is not determined during defrosting operation when the refrigerant state fluctuates greatly, thereby preventing erroneous determination of the state of the control valves 3a to 6b, thereby improving the accuracy of determining the state of the control valves 3a to 6b.

[0075] [9] Furthermore, it is preferable that the air conditioner 100 described in any one of [1] to [8] above is configured to include a judgment time measurement unit 18 that measures the time during which the control valves 3a to 6b are determined to be in a closed state, and a measurement time judgment unit 19 that judges whether the time measured by the judgment time measurement unit 18 exceeds the judgment time.

[0076] This configuration can prevent the states of the control valves 3a to 6b from being erroneously determined due to unintended noise, etc. This improves the accuracy of determining the states of the control valves 3a to 6b.

[0077]

[10] Furthermore, the air conditioner 100 described in [9] above is preferably configured to include a notification unit 20 that notifies that the control valves 3a to 6b are closed when the measurement time determination unit 19 determines that the time measured by the determination time measurement unit 18 has exceeded the determination time, and a compressor control unit 21 that stops operation of the compressor 1 when the measurement time determination unit 19 determines that the time measured by the determination time measurement unit 18 has exceeded the determination time.

[0078] According to this configuration, when the control valves 3a to 6b are in the closed state, the operation of the compressor 1 is stopped, thereby preventing the compressor 1 from being damaged.

[0079] The air conditioner 100 is not limited to the configuration of the above-described embodiment, nor is it limited to the above-described effects. Furthermore, the embodiments can be combined. Various modifications can be made to the air conditioner 100 without departing from the spirit and scope of the present invention.

[0080] 1...Compressor, 2...Four-way valve, 3a, 3b...Gas side operating valve, 4a, 4b...Indoor heat exchanger, 5a, 5b...Indoor fan, 6a, 6b...Liquid side operating valve, 7a, 7b...Motor-operated expansion valve, 8...Outdoor heat exchanger, 9...Outdoor fan, 10a, 10b...Gas side piping, 11a, 11b...Liquid side piping, 12a, 12b...Indoor heat exchanger temperature sensor, 13a, 13b...Room temperature sensor, 14...Rotation speed detection unit, 15...Temperature difference detection unit, 16...Determination unit, 17a, 17b...Humidity sensor, 18...Determination time measurement unit, 19...Measurement time determination unit, 20...Notification unit, 21...Compressor control unit, 22...Outdoor air temperature sensor, 100...Air conditioner, A...Indoor unit, B...Indoor unit, C...Outdoor unit

Claims

1. An air conditioner comprising: a plurality of indoor units having indoor heat exchangers; an outdoor unit having a compressor; a plurality of operating valves that open and close the flow of refrigerant between the plurality of indoor units and the outdoor unit; a rotation speed detection unit that detects the rotation speed of the compressor; a temperature difference detection unit that detects the temperature difference between the temperature of the indoor heat exchanger and the temperature of the room in which it is installed; and a judgment unit that judges that the operating valve is in a closed state when the rotation speed detected by the rotation speed detection unit is equal to or greater than a reference value and the temperature difference detected by the temperature difference detection unit is smaller than a close judgment value, wherein the reference value is a threshold value for the rated rotation speed of the compressor determined by the total capacity of the indoor units that are operating.

2. The air conditioner according to claim 1, wherein the determination unit determines that the operating valve is in the open state when the temperature difference is greater than the open determination value.

3. The air conditioner according to claim 1, wherein the determination unit determines the state of the control valve when the rotation speed of the compressor is equal to or higher than a determination upper limit rotation speed.

4. An air conditioner as described in claim 1, wherein the judgment unit does not judge whether the operating valve is in a closed state when the rotation speed of the compressor is equal to or lower than a judgment lower limit rotation speed.

5. The air conditioner according to claim 1, wherein the closing judgment value is set based on the temperature of the room and the humidity of the room during cooling operation.

6. The air conditioner according to claim 1, wherein the closing judgment value is set based on the room temperature and the outside air temperature.

7. The air conditioner according to claim 1, wherein the determination unit determines the states of the plurality of control valves connected to the plurality of indoor units individually.

8. An air conditioner as claimed in claim 1, wherein the determination unit does not determine the state of the operating valve during defrost operation.

9. An air conditioner as claimed in any one of claims 1 to 8, comprising: a judgment time measurement unit which measures the time for which the operating valve is judged to be in a closed state; and a measurement time judgment unit which judges whether the time measured by the judgment time measurement unit exceeds a judgment time.

10. An air conditioner as described in claim 9, comprising: a notification unit that notifies that the operating valve is in a closed state when the measurement time determination unit determines that the time measured by the determination time measurement unit has exceeded the determination time; and a compressor control unit that stops operation of the compressor when the measurement time determination unit determines that the time measured by the determination time measurement unit has exceeded the determination time.

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