air conditioner

Abstract

We provide air conditioning systems that offer high levels of comfort. [Solution] The air conditioner 100 comprises an outdoor unit 30 having an outdoor heat exchanger 12 and an outdoor fan 13, and an outdoor temperature sensor 34; an indoor unit 20 having an indoor heat exchanger 15 and an indoor fan 16, and an indoor temperature sensor 28; and a control unit 40 that performs a drying operation to dry the inside of the indoor unit 20 after the cooling or dehumidifying operation has stopped. The drying operation includes a fan operation as a mode of operation, but does not include a heating operation. The control unit 40 will not perform the drying operation even after the cooling or dehumidifying operation has stopped if at least one of the indoor temperature and the outdoor temperature is below a predetermined value.

Description

Technical Field

[0001] This disclosure relates to an air conditioner.

Background Art

[0002] Regarding the drying operation for drying the interior of the indoor unit, for example, the technique described in Patent Document 1 is known. That is, Patent Document 1 describes performing a "first drying operation" in which the indoor fan is operated at a first rotational speed while heating the indoor heat exchanger with the heat of the refrigerant discharged from the compressor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1, since the indoor heat exchanger is heated during the first drying operation, warm air is blown out from the indoor unit. Therefore, in some cases, the comfort of the user may be impaired.

[0005] Therefore, an object of the present disclosure is to provide an air conditioner with high comfort.

Means for Solving the Problems

[0006] To solve the aforementioned problems, the air conditioner according to this disclosure comprises an outdoor unit having an outdoor heat exchanger and an outdoor fan and an outdoor temperature sensor, an indoor unit having an indoor heat exchanger and an indoor fan and an indoor temperature sensor, and a control unit that performs a drying operation to dry the inside of the indoor unit after the cooling or dehumidifying operation has stopped, wherein the drying operation includes a fan operation as a mode of operation but does not include a heating operation, and the control unit refrains from performing the drying operation even after the cooling or dehumidifying operation has stopped if at least one of the indoor temperature and the outdoor temperature is below a predetermined value. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide air conditioners that offer high levels of comfort. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the configuration of an air conditioner according to the first embodiment. [Figure 2] This is a perspective view of the outdoor unit housing of an air conditioner according to the first embodiment, with the side panels and top panel removed. [Figure 3] This is a longitudinal cross-sectional view of the indoor unit of an air conditioner according to the first embodiment. [Figure 4] This is a functional block diagram of an air conditioner according to the first embodiment. [Figure 5] This is a time chart including the drying operation of an air conditioner according to the first embodiment. [Figure 6] This is a flowchart showing the processing of the control unit of the air conditioner according to the first embodiment. [Figure 7] This flowchart shows the processing of the control unit of an air conditioner according to a modified example of the first embodiment. [Figure 8] This is a flowchart showing the processing of the control unit of the air conditioner according to the second embodiment. [Figure 9] This is a flowchart showing the processing of the control unit of the air conditioner according to the third embodiment. [Modes for carrying out the invention]

[0009] ≪First Embodiment≫ <Air Conditioner Configuration> Figure 1 is a diagram showing the configuration of the air conditioner 100 according to the first embodiment. The solid arrows in Figure 1 indicate the flow of refrigerant during the heating cycle. Furthermore, the dashed arrows in Figure 1 indicate the flow of refrigerant in the cooling cycle. The air conditioner 100 is a device that performs air conditioning operations such as cooling, dehumidifying, and heating. As shown in Figure 1, the air conditioner 100 has an outdoor unit 30 which includes a compressor 11, an outdoor heat exchanger 12, an outdoor fan 13, an expansion valve 14, and a four-way valve 17. The air conditioner 100 also has an indoor unit 20 which includes an indoor heat exchanger 15 and an indoor fan 16.

[0010] The compressor 11 is a device that compresses low-temperature, low-pressure gaseous refrigerant and discharges it as high-temperature, high-pressure gaseous refrigerant, and is equipped with a compressor motor 11a as its drive source. Although not shown in Figure 1, an accumulator 18 (see Figure 2) for separating the refrigerant into gas and liquid is connected to the suction side of the compressor 11.

[0011] The outdoor heat exchanger 12 is a heat exchanger in which heat exchange takes place between the refrigerant flowing through its heat transfer tubes 12b (see Figure 2) and the outside air supplied by the outdoor fan 13. The outdoor fan 13 is a fan that supplies outside air to the outdoor heat exchanger 12. The outdoor fan 13 is equipped with an outdoor fan motor 13a, which is its driving source, and is installed near the outdoor heat exchanger 12.

[0012] The expansion valve 14 is a valve that reduces the pressure of the refrigerant condensed in the condenser (either the outdoor heat exchanger 12 or the indoor heat exchanger 15). The refrigerant reduced in pressure by the expansion valve 14 is then led to the evaporator (the other of the outdoor heat exchanger 12 or the indoor heat exchanger 15).

[0013] The indoor heat exchanger 15 is a heat exchanger in which heat exchange is performed between the refrigerant flowing through its heat transfer tubes 15b (see FIG. 3) and the indoor air (the air in the air-conditioned room) sent by the indoor fan 16. The indoor fan 16 is a fan that sends indoor air into the indoor heat exchanger 15. The indoor fan 16 includes an indoor fan motor 16a as a drive source and is installed near the indoor heat exchanger 15.

[0014] The four-way valve 17 is a valve that switches the refrigerant flow path as required according to the operation mode of the air conditioner 100. For example, in the cooling cycle (see the dashed arrows in FIG. 1), in the refrigerant circuit 10, the refrigerant circulates sequentially through the compressor 11, the outdoor heat exchanger 12 (condenser), the expansion valve 14, and the indoor heat exchanger 15 (evaporator). Also, in the heating cycle (see the solid arrows in FIG. 1), in the refrigerant circuit 10, the refrigerant circulates sequentially through the compressor 11, the indoor heat exchanger 15 (condenser), the expansion valve 14, and the outdoor heat exchanger 12 (evaporator).

[0015] FIG. 2 is a perspective view of the outdoor unit 30 with the side plates and top plate removed from the housing 31. The outdoor unit 30 shown in FIG. 2 includes, in addition to the above-described components, a housing 31, a partition plate 32, and an electrical component box 33. The housing 31 houses the compressor 11, the outdoor heat exchanger 12, the outdoor fan 13, etc. The partition plate 32 is a plate-like member that partitions the internal space of the housing 31 into a machine room R1 and a heat exchange room R2.

[0016] The compressor 11, the expansion valve 14, and the accumulator 18 are installed in the machine room R1. Also, in the heat exchange room R2, the outdoor heat exchanger 12 having an L-shaped configuration in plan view and the propeller-type outdoor fan 13 are installed. The outdoor heat exchanger 12 includes a number of fins 12a arranged at a predetermined interval and a plurality of heat transfer tubes 12b penetrating these fins 12a. Heat exchange is performed between the outside air sent by the outdoor fan 13 and the refrigerant flowing through the heat transfer tubes 12b.

[0017] The electrical component box 33 is a box that houses a substrate (not shown) on which circuit components of an outdoor control circuit 42 (see FIG. 4) described later are mounted. In the example of FIG. 2, the electrical component box 33 is disposed above the partition plate 32 so as to straddle the machine room R1 and the heat exchange room R2. Note that the configuration of the outdoor unit 30 shown in FIG. 2 is merely an example and is not limited thereto.

[0018] FIG. 3 is a longitudinal sectional view of the indoor unit 20. As shown in FIG. 3, the indoor unit 20 includes an indoor heat exchanger 15 and an indoor fan 16, and further includes a drain pan 21, a housing 22, filters 23a and 23b, a front panel 24, left and right air direction plates 25, and up and down air direction plates 26.

[0019] The indoor heat exchanger 15 includes a plurality of fins 15a and a plurality of heat transfer tubes 15b passing through these fins 15a. The indoor fan 16 is, for example, a cylindrical cross-flow fan, and is installed on the downstream side of the indoor heat exchanger 15 in the air flow direction. In addition to the indoor fan motor 16a (see FIG. 1) described above, the indoor fan 16 includes a plurality of fan blades 16b and an annular partition plate 16c on which these fan blades 16b are installed.

[0020] The drain pan 21 receives the dew condensation water of the indoor heat exchanger 15 and is installed below the indoor heat exchanger 15. The housing 22 houses the indoor heat exchanger 15, the indoor fan 16, etc. The filters 23a and 23b collect dust from the air flowing toward the indoor heat exchanger 15, and are installed on the upstream side of the indoor heat exchanger 15 in the air flow direction. In the example of FIG. 3, one filter 23a is installed in front of the indoor heat exchanger 15, and the other filter 23b is installed above the indoor heat exchanger 15.

[0021] The front panel 24 is a panel that covers the front filter 23a. Note that the front panel 24 may be configured to be rotatable forward, or may be configured to be fixed without particularly rotating, and either configuration is acceptable.

[0022] The left and right air deflectors 25 are plate-shaped members that adjust the left and right airflow direction of the air blown out from the indoor unit 20. The left and right air deflectors 25 are positioned in the air outlet passage H1 of the indoor unit 20 and are rotated left and right by a motor 25a for the left and right air deflectors (see Figure 4). The upper and lower air deflectors 26 are plate-shaped members that adjust the vertical direction of the air blown out from the indoor unit 20. The upper and lower air deflectors 26 are positioned at the air outlet H2 of the indoor unit 20 and are rotated vertically by the upper and lower air deflector motor 26a (see Figure 4).

[0023] Air drawn in through filters 23a and 23b exchanges heat with the refrigerant flowing through the heat transfer tubes 15b of the indoor heat exchanger 15, and the heat-exchanged air is guided to the discharge air passage H1. The air flowing through the discharge air passage H1 is then guided in a predetermined direction by the left and right air deflectors 25 and the up and down air deflectors 26, and blown out into the air conditioning room through the air outlet H2. Note that the configuration of the indoor unit 20 shown in Figure 3 is just one example and is not limited thereto.

[0024] Figure 4 is a functional block diagram of the air conditioner 100. The indoor unit 20 shown in Figure 4 includes, in addition to the above-mentioned components, a remote control transceiver 27, an indoor temperature sensor 28, an indicator lamp 29, and an indoor control circuit 41. The remote control transceiver 27 exchanges predetermined information with the remote control 50 via infrared communication or the like. The indoor temperature sensor 28 is a sensor that detects the indoor temperature (temperature of the air-conditioned room) and is installed, for example, on the air intake side of the indoor heat exchanger 15 (see Figure 3). The indicator lamp 29 is a lamp that displays the operating status of the air conditioner 100 in a predetermined manner.

[0025] The indoor control circuit 41, although not shown in the diagram, consists of electronic circuits including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and various interfaces. The program stored in the ROM is read and loaded into the RAM, and the CPU then executes various processes.

[0026] As shown in Figure 4, the indoor control circuit 41 comprises a storage unit 41a and an indoor control unit 41b. The storage unit 41a stores a predetermined program in advance, as well as data received from the remote control 50 and detection values ​​from various sensors. The indoor control unit 41b controls the indoor fan motor 16a, as well as the left and right air deflector motors 25a, the up and down air deflector motors 26a, and the indicator lamps 29 according to the predetermined program and various data.

[0027] In addition to the above-described components, the outdoor unit 30 includes an outdoor temperature sensor 34 and an outdoor control circuit 42. The outdoor temperature sensor 34 is a sensor that detects the outdoor temperature (temperature of the outside air) and is installed at a predetermined location on the outdoor unit 30. The detected values ​​of the outdoor temperature sensor 34 are output to the outdoor control circuit 42.

[0028] The outdoor control circuit 42, although not shown in the figure, is composed of electronic circuits including a CPU, ROM, RAM, and various interfaces, and is connected to the indoor control circuit 41 via a communication line. As shown in Figure 4, the outdoor control circuit 42 comprises a storage unit 42a and an outdoor control unit 42b. The storage unit 42a stores a predetermined program in advance, as well as the detected value from the outdoor temperature sensor 34 and data received from the indoor unit 20. The outdoor control unit 42b controls the compressor motor 11a, outdoor fan motor 13a, expansion valve 14, and four-way valve 17 based on the predetermined program and various data.

[0029] The indoor control circuit 41 and the outdoor control circuit 42 are collectively referred to as the control unit 40. The control unit 40 is set to perform a drying operation to dry the inside of the indoor unit 20 after the cooling or dehumidifying operation has stopped.

[0030] <Drying operation> For example, during cooling or dehumidifying operation, the indoor heat exchanger 15 (see Figure 3) functions as an evaporator, causing the air inside the indoor unit 20 to cool and become prone to condensation. Therefore, in conventional technology, after the cooling or dehumidifying operation is stopped, the indoor heat exchanger 15 is made to function as a condenser, and the heat from the heated indoor heat exchanger 15 is used to heat and dry the air inside the indoor unit 20.

[0031] However, with this type of control, warm air is blown out from the indoor unit 20 during the drying operation, which may impair user comfort. For example, if the air-conditioned room is cooled to a suitable temperature by cooling operation, and then warm air is blown out from the indoor unit 20 during the drying operation after the cooling operation has stopped, user comfort may be impaired. It is also possible for the user to disable the drying operation setting, but in this case, moisture from the cooling and dehumidifying operations will remain in the indoor unit 20, making it easier for mold and bacteria to grow.

[0032] Therefore, in the first embodiment, in order to balance the drying operation of the indoor unit 20 with user comfort, when the control unit 40 performs the drying operation after the cooling operation or dehumidification operation (i.e., cooling cycle operation) has stopped, it performs the same control as the fan operation. In other words, the control unit 40 does not perform any special control to heat the indoor heat exchanger 15 (to make it function as a condenser) during the drying operation, and instead drives the indoor fan 16 with the compressor 11 stopped. This prevents user comfort from being compromised during the drying operation. In addition, since the inside of the indoor unit 20 is dried during the drying operation, the growth of mold and bacteria, as well as corrosion of metal components such as the indoor heat exchanger 15, can be suppressed.

[0033] Figure 5 is a time chart including the drying operation (see also Figure 4 as appropriate). In Figure 5, the horizontal axis of each time chart represents time. The vertical axis of each time chart, from top to bottom in Figure 5, shows the state of the compressor 11, as well as the state of the four-way valve 17, expansion valve 14, indoor fan 16, and outdoor fan 13. Although Figure 5 shows the case where cooling operation is performed until time t1, the subsequent control is assumed to be the same even if dehumidification operation is performed instead of cooling operation until time t1.

[0034] If a predetermined stop button is pressed on the remote control 50 during cooling operation, the control unit 40 stops the cooling operation at time t1, and then detects the indoor and outdoor temperatures at times t2 to t3. Specifically, after stopping the cooling (or dehumidifying) operation, the control unit 40 drives the indoor fan 16 (at times t2 to t3), and acquires the indoor temperature from the indoor temperature sensor 28 while the indoor fan 16 is running. As a result, air that has been appropriately mixed in the air conditioning room is taken into the indoor unit 20, which reduces errors in detecting the indoor temperature. The rotation speed of the indoor fan 16 when detecting the indoor temperature is preset to a lower value than that during normal air conditioning operation.

[0035] Similarly, the control unit 40 drives the outdoor fan 13 after the cooling (or dehumidifying) operation has stopped, and acquires the outdoor temperature from the outdoor temperature sensor 34 while the outdoor fan 13 is running. This reduces errors when detecting the outdoor temperature. The rotation speed of the outdoor fan 13 when detecting the outdoor temperature is set to a lower value than that during normal air conditioning operation. These detected indoor and outdoor temperature values ​​are used by the control unit 40 to determine whether or not to perform a drying operation. Details will be described later, but the example in Figure 5 shows a case where predetermined conditions regarding indoor and outdoor temperatures are met, and as a result, a drying operation is performed from time t4.

[0036] During cooling operation up to time t1, the indoor heat exchanger 15 functions as an evaporator, so condensation and frost often form on the indoor heat exchanger 15. However, a drying operation is performed afterward to dry the inside of the indoor unit 20. During the drying operation, the control unit 40 keeps the compressor 11 and outdoor fan 13 stopped while driving the indoor fan 16 at a predetermined rotational speed. Thus, the drying operation includes fan operation but does not include heating operation.

[0037] Here, "including fan operation" as a mode of operation means that the indoor fan 16 is driven while the compressor 11 is kept in a stopped state during the drying operation. Also, "not including heating operation" as a mode of operation means that the indoor heat exchanger 15 is not allowed to function as a condenser during the drying operation. For example, conventional techniques in which heating operation and fan operation are performed sequentially during the drying operation are different from the processing of this embodiment, which "includes fan operation and does not include heating operation," because heating operation is included as a mode of drying operation. In this way, by driving the indoor fan 16 without specifically heating the indoor heat exchanger 15, it is possible to suppress the blowing of hot air from the indoor unit 20 during the drying operation.

[0038] During the drying operation, the upper and lower air deflectors 26 (see Figure 3) of the indoor unit 20 are assumed to remain open. Here, the condition that the upper and lower air deflectors 26 are in an "open state" includes not only when they are open and pointing upwards from the horizontal, but also when they are pointing downwards from the horizontal or are approximately parallel to the horizontal.

[0039] The control unit 40 drives the indoor fan 16 while keeping the upper and lower air deflectors 26 open, allowing air from the air-conditioned room to be drawn into the indoor unit 20. As a result, drying inside the indoor unit 20 is promoted, which suppresses the growth of mold and bacteria, and also suppresses corrosion of metal components such as the indoor heat exchanger 15. In addition, since warm air is not blown out from the indoor unit 20 after the cooling operation stops, user comfort is maintained.

[0040] For example, if the duration of cooling or dehumidifying operation is longer than a predetermined time, the control unit 40 may perform a drying operation after the cooling or dehumidifying operation has stopped. The aforementioned dehumidifying operation may be a so-called reheat dehumidifying operation, or it may be a cooling dehumidifying operation. In addition to the case where the operation is started by the user operating the remote control 50, the dehumidifying operation may also be performed automatically as described below.

[0041] <Automatic dehumidification operation> For example, the system may be set to automatically switch to dehumidification mode during heating or cooling operation without requiring any operation of the remote control 50. In this case, a predetermined data table (not shown) is pre-set, which associates the combination of indoor and outdoor temperatures with whether or not to switch to dehumidification mode. Specifically, during heating operation, the data table is set so that the higher the indoor temperature and the higher the outdoor temperature, the more likely the system is to switch from heating to dehumidification mode. On the other hand, during cooling operation, the data table is set so that the lower the indoor temperature and the lower the outdoor temperature, the more likely the system is to switch from cooling to dehumidification mode.

[0042] In the aforementioned data table, if a combination of detected indoor and outdoor temperatures is associated with the control for switching to dehumidification operation, the control unit 40 switches from heating operation (or cooling operation) to dehumidification operation. The control unit 40 then performs dehumidification operation to maintain a comfortable temperature and humidity while suppressing overheating (or overcooling) of the air-conditioned room. If the stop button on the remote control 50 is pressed while automatic dehumidification operation is in progress, the dehumidification operation will stop.

[0043] For example, suppose the system automatically switches from heating operation to dehumidification operation, and then the dehumidification operation is stopped by operating the remote control 50. After the dehumidification operation is stopped in this way, if a drying operation (similar to the fan operation) as shown in Figure 5 is performed uniformly, regardless of the detected indoor and outdoor temperatures, the user's comfort may be compromised by the cold air blown out from the indoor unit 20. This is because, during the dehumidification operation immediately preceding the drying operation, the indoor heat exchanger 15 functions as an evaporator, and the air taken into the indoor unit 20 during the drying operation is cooled by heat exchange with the indoor heat exchanger 15. Therefore, in the first embodiment, the control unit 40 determines whether or not to perform the drying operation based on the indoor temperature and the detected indoor temperature values.

[0044] Figure 6 is a flowchart showing the processing of the control unit of the air conditioner (see also Figure 4 as appropriate). In the example shown in Figure 6, the case in step S101 where cooling operation is performed is described, but the processing in steps S102 to S106 is the same even if dehumidification operation is performed instead of cooling operation. The aforementioned dehumidification operation may be started by the user operating the remote control 50, or it may be automatically switched to dehumidification operation without operation of the remote control 50 while cooling operation or heating operation is being performed. This point is the same in the modified example of the first embodiment (see Figure 7), as well as in the second embodiment (see Figure 8) and the third embodiment (see Figure 9).

[0045] In step S101, the control unit 40 performs cooling operation. This cooling operation is started by the user operating the remote control 50. Next, in step S102, the control unit 40 stops the cooling operation. It is assumed that the user pressed the stop button on the remote control 50 when stopping the cooling operation.

[0046] In step S103, the control unit 40 reads the detected values ​​for the indoor temperature and outdoor temperature. That is, the control unit 40 reads the detected value for the indoor temperature from the indoor temperature sensor 28 and the detected value for the outdoor temperature from the outdoor temperature sensor 34. As described above, when acquiring the detected values ​​for the indoor and outdoor temperatures, it is preferable for the control unit 40 to drive the indoor fan 16 and the outdoor fan 13 at a predetermined rotational speed (times t2 to t3 in Figure 5). This reduces errors when detecting the indoor and outdoor temperatures.

[0047] In step S104, the control unit 40 determines whether the indoor temperature is below a first predetermined value. This first predetermined value (for example, 20°C) is a threshold value for the indoor temperature and is set in advance as a criterion for determining whether or not to perform the drying operation (S106). For example, the first predetermined value is set based on whether or not the user may feel chilly when cold air is blown out from the indoor unit 20 during the drying operation.

[0048] Furthermore, it is preferable to set the first predetermined value to a value higher than the lower limit of the set temperature in cooling operation (for example, 16°C). This prevents the drying operation from being performed and cold air from being blown out from the indoor unit 20 even when the air-conditioned room is relatively cold. If the indoor temperature is less than the first predetermined value in step S104 (S104: Yes), the control unit 40 proceeds to step S105.

[0049] In step S105, the control unit 40 determines whether the outdoor temperature is below a second predetermined value. This second predetermined value (for example, 18°C) is a threshold value for the outdoor temperature and is set in advance as a criterion for determining whether or not to perform the drying operation (S106). It is preferable to set the second predetermined value to a value lower than the first predetermined value (for example, 16°C). This makes it possible to perform the drying operation (S106) even when the set temperature for cooling operation is low and the indoor temperature is below the first predetermined value, because the outdoor temperature often exceeds the second predetermined value, especially in summer. For example, even if the user prefers to set the set temperature for cooling operation low each time (below the first predetermined value), the inside of the indoor unit 20 can be dried by the drying operation after the cooling operation.

[0050] If the outdoor temperature is below the second predetermined value in step S105 (S105: Yes), the control unit 40 terminates the series of processes without performing a drying operation (END). In this way, after the cooling operation (or dehumidification operation) is stopped, if the indoor temperature is below the first predetermined value (S104: Yes), and furthermore, the outdoor temperature is below the second predetermined value (S105: Yes), the control unit 40 does not perform a drying operation. This prevents cold air (cold air associated with the drying operation) from being blown out of the indoor unit 20 after the cooling operation is stopped, which could make the user feel chilly.

[0051] Furthermore, if the indoor temperature is above a first predetermined value in step S104 (S104: No), or if the outdoor temperature is above a second predetermined value in step S105 (S105: No), the control unit 40 proceeds to step S106. In step S106, the control unit 40 performs a drying operation. That is, the control unit 40 opens the upper and lower air deflector plates 26 (see Figure 3) and drives the indoor fan 16 (see Figure 3) with the compressor 11 (see Figure 1) stopped. As a result, air from the air conditioning room is drawn into the indoor unit 20, promoting drying of the inside of the indoor unit 20. During the drying operation, the indicator lamp 29 is assumed to light up to a predetermined value. After performing the operation in step S106, the control unit 40 terminates the series of operations (END).

[0052] Furthermore, it is preferable that the settings related to the drying operation (including the processing steps S103 to S106 in Figure 6) are enabled from the initial setup of the air conditioner 100. This ensures that the drying operation is performed automatically after the cooling and dehumidifying operations, even if the user does not specifically set the drying operation when starting to use the air conditioner 100. Therefore, it is possible to prevent situations where the air conditioner 100 is used for a long period of time without the user setting the drying operation, even though the user actually wanted to use the drying operation.

[0053] Furthermore, if a predetermined stop operation is performed using the remote control 50 or a mobile terminal (not shown) while the drying operation is in progress, the control unit 40 should stop the drying operation (cancel the drying operation). This reflects the user's intention to stop the drying operation in the control, thereby enhancing user comfort and increasing the user's freedom of operation.

[0054] According to the first embodiment, the control unit 40 performs a drying operation after the cooling or dehumidifying operation has stopped. This promotes drying inside the indoor unit 20, thereby suppressing the growth of mold and bacteria, as well as preventing corrosion of metal components. Furthermore, since the same control as the fan operation is performed during the drying operation, user comfort is maintained. In addition, since there is no particular need to drive the compressor 11 during the drying operation, the power consumption of the air conditioner 100 can be reduced.

[0055] Furthermore, if the indoor temperature is below the first predetermined value (S104: Yes in Figure 6), and the outdoor temperature is also below the second predetermined value (S105: Yes), the control unit 40 will not perform the drying operation. In other words, if there is a high possibility that the user will feel chilly from the cold air blown out from the indoor unit 20, the drying operation will not be performed, thus maintaining the user's comfort. Furthermore, even if the indoor temperature is below the first predetermined value (S104: Yes in Figure 6), if the outdoor temperature is at or above the second predetermined value (S105: No), the drying operation will be performed (S106). Therefore, even if the set temperature for the cooling operation is relatively low, the inside of the indoor unit 20 can be dried by the subsequent drying operation.

[0056] Furthermore, according to the first embodiment, even if the dehumidification operation is stopped by the remote control 50 after the system has automatically switched from heating operation to dehumidification operation, if the outside is cold and the temperature in the air-conditioned room is low (S104: Yes, S105: Yes in Figure 6), the drying operation is prohibited. Therefore, it is possible to prevent the user from feeling chilly during the drying operation after the dehumidification operation. In this way, according to the first embodiment, it is possible to improve user comfort while preventing the inside of the indoor unit 20 from remaining in a high-humidity state.

[0057] <<Variations of the First Embodiment>> Figure 7 is a flowchart showing the processing of the control unit of an air conditioner according to a modified example of the first embodiment. Figure 7 is a flowchart of the first embodiment (see Figure 6) with the processing of step S107 added. Specifically, if the indoor temperature is below a first predetermined value (S104: Yes), and the outdoor temperature is also below a second predetermined value (S105: Yes), the control unit 40 proceeds to the processing of step S107 without performing any drying operation.

[0058] In step S107, the control unit 40 determines whether a predetermined time has elapsed since the cooling operation stopped. The predetermined time is a threshold value that serves as a criterion for determining whether or not to perform the determination process (S104, S105) regarding the indoor temperature and outdoor temperature again, and is set in advance. If the predetermined time has not elapsed since the cooling operation stopped in step S107 (S107: No), the control unit 40 repeats the process in step S107.

[0059] Furthermore, if a predetermined time has elapsed since the cooling operation stopped in step 107 (S107: Yes), the control unit 40 returns to the process in step S104. Then, if the indoor temperature is above a first predetermined value (S104: No), or if the outdoor temperature is above a second predetermined value (S105: No), the control unit 40 performs a drying operation (S106). As a result, the probability (chance) of the drying operation being performed is higher than in the first embodiment, and the inside of the indoor unit 20 can be kept clean.

[0060] ≪Second Embodiment≫ The second embodiment differs from the first embodiment in that the feasibility of drying operation is determined based on the indoor temperature, while the outdoor temperature is not particularly used in determining the feasibility of drying operation. Other aspects (such as the configuration of the air conditioner 100: see Figures 1 to 4) are the same as in the first embodiment. Therefore, the differences from the first embodiment will be explained, and the overlapping parts will be omitted.

[0061] Figure 8 is a flowchart showing the processing of the control unit of the air conditioner according to the second embodiment (see also Figure 4 as appropriate). As shown in Figure 8, after performing cooling operation (S201) and then stopping the cooling operation by operating the remote control 50 (S202), the control unit 40 proceeds to step S203. In step S203, the control unit 40 reads the detected indoor temperature from the indoor temperature sensor 28.

[0062] Next, in step S204, the control unit 40 determines whether the indoor temperature is below a first predetermined value. If the indoor temperature is below the first predetermined value in step S204 (S204: Yes), the control unit 40 terminates the series of processes without performing a drying operation (END). In other words, if the indoor temperature is below the first predetermined value, the control unit 40 refrains from performing a drying operation even after the cooling operation (or dehumidification operation) has stopped. This prevents the blowing of cold air from the indoor unit 20, thus maintaining user comfort.

[0063] Furthermore, if the indoor temperature is above a first predetermined value in step S204 (S204: No), the control unit 40 proceeds to step S205. In step S205, the control unit 40 performs a drying operation. This dries the inside of the indoor unit 20, suppressing the growth of mold and bacteria, as well as corrosion of metal components such as the indoor heat exchanger 15. After performing the operation in step S205, the control unit 40 terminates the series of operations (END).

[0064] According to the second embodiment, the control unit 40 determines whether or not to perform the drying operation based on the detected indoor temperature. In other words, there is no particular need to use the detected outdoor temperature, so the processing can be simplified compared to the first embodiment.

[0065] ≪Third Embodiment≫ The third embodiment differs from the first embodiment in that drying operation is prohibited when the indoor temperature is below a first predetermined value or when the outdoor temperature is below a second predetermined value. Other aspects (such as the configuration of the air conditioner 100: see Figures 1 to 4) are the same as in the first embodiment. Therefore, the differences from the first embodiment will be explained, and the overlapping parts will be omitted.

[0066] Figure 9 is a flowchart showing the processing of the control unit of the air conditioner according to the third embodiment (see also Figure 4 as appropriate). Steps S101 to S104 in Figure 9 are the same as in the first embodiment (see Figure 6), so their explanation will be omitted. If the room temperature is less than the first predetermined value in step S104 (S104: Yes), the control unit 40 terminates the series of processes without performing any drying operation (END). If the room temperature is equal to or greater than the first predetermined value in step S104 (S104: No), the control unit 40 proceeds to step S305.

[0067] In step S305, the control unit 40 determines whether the outdoor temperature is below a second predetermined value. If the outdoor temperature is below the second predetermined value in step S305 (S305: Yes), the control unit 40 terminates the series of processes without performing a drying operation (END). In this way, the control unit 40 does not perform a drying operation if the indoor temperature is below a first predetermined value (S104: Yes) or if the outdoor temperature is below a second predetermined value (S305: Yes). This prevents cold air from being blown out of the indoor unit 20 (drying operation being performed) in an environment where the user is likely to feel chilly.

[0068] Furthermore, if the outdoor temperature is above the second predetermined value in step S305 (S305: No), the control unit 40 proceeds to step S306. In other words, if the indoor temperature is above the first predetermined value (S104: No), and the outdoor temperature is above the second predetermined value (S305: No), the control unit 40 proceeds to step S306.

[0069] In step S306, the control unit 40 performs a drying operation. In this case, since the indoor and outdoor temperatures are not very low, there is little risk of user comfort being impaired even if cold air is blown out from the indoor unit 20 during the drying operation. After performing the process in step S306, the control unit 40 terminates the series of processes (END).

[0070] According to the third embodiment, if the outdoor temperature is below the second predetermined value (S305: Yes), the control unit 40 does not perform the drying operation. This prevents the air-conditioned room from being cooled by the drying operation during winter when it is cold outside and the air-conditioned room is prone to getting cold.

[0071] <<Other variations>> Although the air conditioner 100 relating to this disclosure has been described in detail in each embodiment, the invention is not limited to these descriptions and various modifications can be made. For example, in the first and third embodiments (see Figures 6 and 9), the possibility of drying operation is determined based on the indoor and outdoor temperatures, and in the second embodiment (see Figure 8), the possibility of drying operation is determined based on the indoor temperature. However, the system is not limited to these cases. For example, the possibility of drying operation may be determined based on the outdoor temperature, while the indoor temperature may not be used in the determination of whether or not to perform the drying operation. Specifically, if the outdoor temperature is below a second predetermined value after the cooling or dehumidifying operation has stopped, the control unit 40 may refrain from performing the drying operation. By prohibiting the drying operation when the outside is cold and the air-conditioned room is prone to cooling, user comfort can be easily maintained. On the other hand, if the outdoor temperature is above the second predetermined value after the cooling or dehumidifying operation has stopped, the control unit 40 will perform the drying operation. This allows the inside of the indoor unit 20 to be dried.

[0072] In summary, if at least one of the indoor temperature or outdoor temperature is below a predetermined value, the control unit 40 should not perform drying operation even after the cooling or dehumidifying operation has stopped. This will prevent drying operation when the indoor temperature is below a predetermined value (first predetermined value) or when the outdoor temperature is below a predetermined value (second predetermined value), thereby enhancing user comfort. Furthermore, when the control unit 40 starts the drying operation, it is preferable to continue the drying operation even if at least one of the indoor temperature and outdoor temperature falls below a predetermined value during the execution of the drying operation. By completing the drying operation, the inside of the indoor unit 20 is thoroughly dried, which suppresses the growth of mold and bacteria in the indoor unit 20 and corrosion of metal components.

[0073] Furthermore, regarding the automatic dehumidification operation described above, for example, the following control may be implemented. That is, when predetermined conditions regarding the indoor temperature and outdoor temperature are met during cooling or heating operation, the control unit 40 switches from cooling or heating operation to dehumidification operation. Then, if the dehumidification operation is stopped by the operation of the remote control 50 or a portable terminal (not shown) after switching to dehumidification operation, and at least one of the indoor temperature and outdoor temperature is below a predetermined value, the control unit 40 will not perform drying operation even after the dehumidification operation has stopped. This prevents, for example, the situation where, after the system automatically switches from heating operation to dehumidification operation in winter, the system stops the dehumidification operation by the operation of the remote control 50, and cold air is blown out from the indoor unit 20 (drying operation is performed) at a time unintended by the user.

[0074] Furthermore, the user can cancel the drying operation setting by operating the remote control 50 or a mobile terminal. The user can also change the operation mode from a drying operation without heating (see Figure 5) to a drying operation including heating (a drying operation accompanied by heating of the indoor heat exchanger 15) by operating the remote control 50 or a mobile terminal. If the operation is changed to a drying operation including heating, the drying operation will be executed without any special determination processing in steps S104 and S105 of Figure 6 after the cooling or dehumidifying operation has stopped.

[0075] Furthermore, if the cooling or dehumidifying operation is stopped by a timer setting (so-called off-timer), the prohibition on drying operation may be waived. This is because the cooling or dehumidifying operation is often stopped by the off-timer while the user is sleeping, and the operating noise of the indoor fan 16 may be unpleasant to the user or may wake the user while they are sleeping.

[0076] Furthermore, the numerical examples of the first and second predetermined values ​​described in each embodiment are merely examples, and can be appropriately changed within a range that achieves the desired effect, depending on the specifications and purpose of the air conditioner 100. For example, the first and second predetermined values ​​may each be set within a range of 10°C or higher and less than 20°C. Furthermore, while each embodiment describes a case where the second predetermined value for the outdoor temperature is set to a lower value than the first predetermined value for the indoor temperature, the invention is not limited to this. That is, the second predetermined value may be set to a higher value than the first predetermined value. Also, the first predetermined value and the second predetermined value may be equal.

[0077] Furthermore, in the first embodiment, the case in which the indoor fan 16 is driven when the indoor temperature is detected, then the indoor fan 16 is stopped, and then the indoor fan 16 is driven again during the drying operation was described (see Figure 5), but it is not limited to this. That is, the indoor fan 16 may be driven continuously from the time the indoor temperature is detected through to the drying operation. In this case, the control unit 40 shall increase the rotational speed of the indoor fan 16 at the start of the drying operation.

[0078] Furthermore, each embodiment can be combined as appropriate. For example, a modified version of the first embodiment (see Figure 7) can be combined with the second embodiment (see Figure 8). It is also possible to combine a modified version of the first embodiment (see Figure 7) with the third embodiment (see Figure 9). Many other combinations are also possible.

[0079] Furthermore, although the embodiment described an air conditioner 100 (see Figure 1) equipped with a four-way valve 17, it is not limited to this configuration. That is, the four-way valve 17 may be omitted from the air conditioner 100 as appropriate, and it may be configured for cooling only or heating only.

[0080] Furthermore, although the embodiment described a configuration in which one indoor unit 20 (see Figure 1) and one outdoor unit 30 (see Figure 1) are provided, the system is not limited to this configuration. That is, multiple indoor units connected in parallel may be provided, and multiple outdoor units connected in parallel may also be provided. Furthermore, although the embodiment described the case where the air conditioner 100 (see Figure 1) is a room air conditioner, the embodiment can also be applied to various types of air conditioners such as packaged air conditioners and multi-split air conditioners for buildings.

[0081] Furthermore, the embodiments are described in detail for the purpose of clearly illustrating this disclosure and are not necessarily limited to having all the configurations described. In addition, it is possible to add, delete, or replace some of the configurations in the embodiments with other configurations. Furthermore, the mechanisms and configurations described above are those deemed necessary for explanatory purposes and do not necessarily represent all of the mechanisms and configurations shown in the actual product. [Explanation of Symbols]

[0082] 10 Refrigerant Circuit 11 Compressor 12 Outdoor heat exchanger 13 Outdoor fan 14. Expansion valve 15 Indoor heat exchanger 16 Indoor fan 17 Four-way valve 20 Indoor unit 28. Indoor temperature sensor 30 Outdoor unit 34 Outdoor temperature sensor 40 Control Unit 50 Remote Controls 100 Air conditioners

Claims

1. An outdoor unit having an outdoor heat exchanger and an outdoor fan, and an outdoor temperature sensor, An indoor unit having an indoor heat exchanger and an indoor fan, and an indoor temperature sensor, The system includes a control unit that performs a drying operation to dry the inside of the indoor unit after the cooling or dehumidifying operation has stopped, The aforementioned drying operation includes a fan operation but does not include a heating operation. The control unit of the air conditioner refrains from performing the drying operation even after the cooling or dehumidifying operation has stopped, if at least one of the indoor temperature and the outdoor temperature is below a predetermined value.

2. The settings related to the drying operation mentioned above are enabled from the initial setup of the air conditioner. An air conditioner according to claim 1, characterized by the following:

3. The aforementioned predetermined value is higher than the lower limit of the set temperature during cooling operation. An air conditioner according to claim 1, characterized by the following:

4. The control unit drives the indoor fan after the cooling or dehumidifying operation has stopped, obtains the indoor temperature from the indoor temperature sensor while the indoor fan is running, and determines whether or not to perform the drying operation based on the indoor temperature. An air conditioner according to claim 1, characterized by the following:

5. The control unit drives the outdoor fan after the cooling or dehumidifying operation has stopped, obtains the outdoor temperature from the outdoor temperature sensor while the outdoor fan is running, and determines whether or not to perform the drying operation based on the outdoor temperature. An air conditioner according to claim 1, characterized by the following:

6. A first predetermined value is set as the predetermined value for the indoor temperature, A second predetermined value is set as the predetermined value for the outdoor temperature. The control unit shall not perform the drying operation if, after the cooling or dehumidifying operation has stopped, the indoor temperature is below the first predetermined value and the outdoor temperature is also below the second predetermined value. An air conditioner according to claim 1, characterized by the following:

7. The second predetermined value is set to a value lower than the first predetermined value. An air conditioner according to claim 6, characterized by the following:

8. When the control unit starts the drying operation, it will continue the drying operation even if at least one of the indoor temperature and outdoor temperature falls below the predetermined value during the execution of the drying operation. An air conditioner according to claim 1, characterized by the following:

9. The control unit will stop the drying operation if a predetermined stop operation is performed using a remote control or mobile terminal while the drying operation is in progress. An air conditioner according to claim 1, characterized by the following:

10. The control unit, During cooling or heating operation, if the specified conditions regarding indoor and outdoor temperatures are met, the system will switch to dehumidification operation. If the dehumidification operation is stopped by operating the remote control or mobile device after switching to dehumidification operation, and at least one of the indoor temperature and outdoor temperature is below the predetermined value, the drying operation will not be performed even after the dehumidification operation has been stopped. An air conditioner according to claim 1, characterized by the following:

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