Air conditioner and method of controlling the same

Abstract

To sufficiently attain the effect of suppressing corrosion of piping caused by organic acid.SOLUTION: An air conditioner includes an indoor heat exchanger, a dew point temperature calculating section for calculating an indoor dew point temperature, a temperature detecting section for detecting a heat exchanger temperature of the indoor heat exchanger, and a control device. The control device can execute an anti-frost mode in which the temperature of the indoor heat exchanger is raised and the indoor unit is made to execute anti-frost operation when the heat exchanger temperature detected by the temperature detecting section is equal to or lower than a first threshold set in advance, and a cleaning mode in which the indoor heat exchanger is cooled to generate dew condensation water in a gap between piping and a fin and the gap is cleaned by the dew condensation water when the heat exchanger temperature detected by the temperature detecting section is higher than the dew point temperature calculated by the dew point temperature calculating section. In the cleaning mode, the indoor unit is made to execute the anti-frost operation when the heat exchanger temperature detected by the temperature detecting section is equal to or lower than a second threshold which is set lower than the first threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an air conditioner and a method for controlling an air conditioner. [Background technology]

[0002] Patent document 1 discloses a configuration in which a surface condensation operation is performed to cause condensation on the surface of the fins by performing dehumidification or cooling operation in order to clean dust, mold spores, etc. that have adhered to the surface of the fins of an indoor heat exchanger of an air conditioner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-52844 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when an indoor heat exchanger comes into contact with organic acids such as formic acid and acetic acid contained in indoor air fresheners or wallpaper adhesives, it can have a detrimental effect on the metal that makes up the indoor heat exchanger. In particular, when condensation water accumulates in the gap between the fins and the pipe through which the heat medium flows, the organic acid adhering near the gap dissolves in the condensation water, facilitating corrosion of the pipe.

[0005] The configuration described in Patent Document 1 causes condensation on the surface of the fins in order to clean away dust, mold spores, etc. that have adhered to the surface of the fins, but this may not be sufficient to inhibit corrosion of piping caused by organic acids. Furthermore, if surface condensation operation continues due to dehumidification or cooling operation, the temperature of the indoor heat exchanger may drop too low, satisfying the conditions for starting anti-frost operation. When anti-frost operation starts, the temperature of the indoor heat exchanger rises, causing the surface condensation operation to be stopped. This also means that the effect of suppressing pipe corrosion by organic acids may not be fully achieved.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an air conditioning apparatus and a method for controlling an air conditioning apparatus that can fully achieve the effect of suppressing corrosion of piping by organic acids. [Means for solving the problem]

[0007] In order to solve the above problems, an air conditioner according to the present disclosure is an air conditioner including an outdoor unit and an indoor unit, and includes an indoor heat exchanger provided in the indoor unit, the indoor heat exchanger including piping through which a heat medium supplied from the outdoor unit flows and fins provided around the piping, a dew point temperature calculation unit that calculates a dew point temperature in the room, a temperature detection unit that detects a heat exchanger temperature of the indoor heat exchanger, and a control device, and when the heat exchanger temperature detected by the temperature detection unit becomes equal to or lower than a predetermined first threshold, the control device increases the temperature of the indoor heat exchanger to reduce the dew point temperature in the room. The control unit can execute an anti-frost mode in which the indoor unit performs anti-frost operation, and a cleaning mode in which, when the heat exchanger temperature detected by the temperature detection unit is higher than the dew point temperature calculated by the dew point temperature calculation unit, the indoor heat exchanger is cooled to produce condensation water in the gap between the piping and the fins, and a cleaning operation is executed to clean the gap with the condensation water.In the cleaning mode, when the heat exchanger temperature detected by the temperature detection unit is equal to or lower than a second threshold value set lower than the first threshold value, the indoor unit is caused to perform anti-frost operation.

[0008] A control method for an air conditioner according to the present disclosure is a control method for an air conditioner including an outdoor unit and an indoor unit, and includes the steps of: calculating an indoor dew point temperature; detecting a heat exchanger temperature of an indoor heat exchanger of the indoor unit; causing the indoor unit to perform anti-frost operation when the heat exchanger temperature becomes equal to or lower than a predetermined first threshold; and causing the indoor unit to perform a cleaning operation when the heat exchanger temperature is higher than the dew point temperature, which cools the indoor heat exchanger, generates condensation water in gaps between a pipe of the indoor heat exchanger through which a heat medium supplied from the outdoor unit flows and fins provided around the pipe, and cleans the gaps with the condensation water; and in the step of causing the cleaning operation, causes the indoor unit to perform anti-frost operation when the heat exchanger temperature becomes equal to or lower than a second threshold that is set lower than the first threshold. [Effects of the Invention]

[0009] According to the air conditioner and the method for controlling the air conditioner of the present disclosure, it is possible to obtain a sufficient effect of suppressing corrosion of pipes caused by organic acids. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating a configuration of an air conditioning apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing a schematic configuration of an indoor heat exchanger of the air conditioning apparatus. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 2 is a functional block diagram of a control device for the air conditioning apparatus. [Figure 5] 4 is a flowchart showing the procedure of a control method in the control device. [Figure 6] 4 is a flowchart showing the procedure of a control method in the control device. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments for carrying out an air conditioner and a control method for an air conditioner according to the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to these embodiments. (Configuration of air conditioning device) As shown in FIG. 1, the air conditioner 1 includes an outdoor unit 2, an indoor unit 3, and a control device 4.

[0012] (Outdoor unit configuration) The outdoor unit 2 is installed outside the building. The outdoor unit 2 is connected to the indoor unit 3 via connection piping 5. The outdoor unit 2 includes a compressor 21, an outdoor heat exchanger (not shown), an expansion valve (not shown), and a switching valve (not shown).

[0013] The compressor 21, outdoor heat exchanger, expansion valve, and switching valve are provided on a medium circuit (not shown). The compressor 21 compresses the heat medium (so-called refrigerant) flowing in the heat medium piping that makes up the medium circuit. The outdoor heat exchanger exchanges heat between the outdoor air and the heat medium flowing in the heat medium piping. The expansion valve expands the heat medium that has passed through the outdoor heat exchanger. The switching valve switches the flow of the heat medium in the medium circuit to switch between cooling operation and heating operation.

[0014] (Indoor unit configuration) The indoor unit 3 is installed inside a building. The indoor unit 3 conditions the air inside the room by performing cooling operation, heating operation, dehumidification operation, etc. The indoor unit 3 includes a housing 31, an indoor heat exchanger 33, a fan 34, a louver 35, a heat exchanger temperature sensor (temperature detection unit) 37, and a humidity sensor 38.

[0015] The indoor heat exchanger 33 is provided in the housing 31. As shown in FIGS. 2 and 3, the indoor heat exchanger 33 has a pipe 331 and a plurality of fins 332. The pipe 331 is connected to the outdoor unit 2 via a connection pipe 5. The pipe 331 constitutes a part of a medium circuit (not shown). The heat medium supplied from the outdoor unit 2 by the compressor 21 flows through the pipe 331. The fins 332 are provided around the pipe 331. A plurality of fins 332 are arranged side by side in the extension direction of the pipe 331. Each fin 332 integrally includes a plate-shaped portion 332a intersecting the extension direction of the pipe 331 and a cylindrical portion 332b protruding from the plate-shaped portion 332a in the extension direction of the pipe 331. The cylindrical portion 332b is joined to the outer peripheral surface of the pipe 331 by brazing or the like. As shown in FIG. 3, in such an indoor heat exchanger 33, a gap S is formed between the outer peripheral surface of the pipe 331 and two fins 332 adjacent to each other in the extension direction of the pipe 331.

[0016] 1, the fan 34 is provided inside the housing 31. The fan 34 sends air to the indoor heat exchanger 33. The housing 31 is formed with an air outlet 31h through which air that has passed through the indoor heat exchanger 33 is blown out of the housing 31. A louver 35 is provided at the air outlet 31h. By adjusting the opening degree of the louver 35, it is possible to adjust the blowing direction and amount of air from the air outlet 31h.

[0017] The heat exchanger temperature sensor 37 detects the heat medium temperature at the heat medium outlet of the indoor heat exchanger 33 as the heat exchanger temperature. The humidity sensor 38 detects the humidity in the room where the indoor unit 3 is installed.

[0018] (Control device configuration) The control device 4 can be configured using a computer such as a microcomputer or a CPU (Central Processing Unit), and hardware such as peripheral circuits and devices of the computer. In this embodiment, the control device 4 is configured by a control board on which a microcomputer is mounted. The control device 4 controls the operation of the compressor 21 of the outdoor unit 2 and the fan 34 and louver 35 of the indoor unit 3 in accordance with a set temperature and other parameters set externally. As shown in FIG. 4 , the control device 4 has a functional configuration formed by a combination of hardware and software such as a program executed by the computer, and includes an information acquisition unit 41, a dew-point temperature calculation unit 42, an operation control unit 43, and an output unit 44.

[0019] The information acquisition unit 41 acquires information on the heat exchanger temperature detected by the heat exchanger temperature sensor 37 and the humidity detected by the humidity sensor 38 at preset time intervals.

[0020] The dew-point temperature calculation unit 42 calculates the dew-point temperature in the room where the indoor unit 3 is installed, based on the heat exchanger temperature and humidity acquired by the information acquisition unit 41. The dew-point temperature calculation unit 42 calculates the dew-point temperature Td, for example, by the following formula (1). Td=237.3log 10 (6.1078 / e) / {log 10 (e / 6.1078)-7.5} …(1) where: e=e s ×RH / 100 e s =6.1078×10 7.5t / (t+237.3) where t is the heat exchanger temperature, RH is the indoor humidity, and e s is the saturated water vapor pressure, and e is the water vapor pressure of air.

[0021] The indoor unit 3 allows a user of the air conditioning apparatus 1 to select from a plurality of operation modes, such as heating operation and cooling operation, using a remote controller (not shown) of the indoor unit 3. The operation control unit 43 generates control signals for controlling the operation of the outdoor unit 2 and the indoor unit 3 according to the selected operation mode.

[0022] The output unit 44 outputs the control signal generated by the operation control unit 43 to the outdoor unit 2 and the indoor unit 3. The outdoor unit 2 and the indoor unit 3 operate based on the control signal output from the output unit 44.

[0023] Furthermore, the operation control unit 43 of the present disclosure is capable of executing an antifrost mode in which the indoor unit 3 performs antifrost operation, and a cleaning mode in which the indoor unit 3 performs cleaning operation in which the gap S is cleaned with condensed water. The anti-frost mode is implemented to prevent the indoor heat exchanger 33 from forming frost when the indoor unit 3 is in cooling or dehumidifying operation and the indoor heat exchanger 33 becomes cold. In the anti-frost mode, the operation control unit 43 reduces the rotation speed of the compressor 21 to increase the temperature of the indoor heat exchanger 33 and prevent frost from forming on the indoor heat exchanger 33. The anti-frost mode can also melt frost that has formed on the indoor heat exchanger 33. When the heat exchanger temperature detected by the temperature detection unit 37 falls below a predetermined first threshold while the indoor unit 3 is in cooling or dehumidifying operation, the operation control unit 43 transitions to the anti-frost mode and causes the indoor heat exchanger 33 to start anti-frost operation. Here, the first threshold, which is the start condition for anti-frost operation, can be set to, for example, 5°C. When the heat exchanger temperature detected by the heat exchanger temperature sensor 37 becomes 5°C or lower, the operation control unit 43 starts the anti-frost operation by reducing the rotation speed of the compressor 21. When the heat exchanger temperature detected by the heat exchanger temperature sensor 37 becomes higher than, for example, 8°C (hereinafter, this may be referred to as the third threshold value), after the start of the anti-frost operation, the operation control unit 43 returns the rotation speed of the compressor 21 to the original rotation speed and ends the anti-frost operation.

[0024] The cleaning mode is performed after the indoor unit 3 has finished cooling or dehumidifying operation and the heat exchanger temperature of the indoor heat exchanger 33 is higher than the dew point temperature at that time. In the cleaning mode, the indoor heat exchanger 33 is cooled to generate condensation water in the gap S between the pipe 331 and the fins 332, and a cleaning operation is performed to clean the gap S with the condensation water. The operation control unit 43 transitions to the cleaning mode when preset conditions for starting the cleaning operation are met after the indoor unit 3 has finished cooling or dehumidifying operation. In the cleaning mode, the temperature of the indoor heat exchanger 33 is lowered to cause condensation to form in the indoor atmosphere. This causes condensation water to form in the gap S between the pipe 331 and the fins 332 of the indoor heat exchanger 33. The generated condensation water cleans the gap S. The condensation water flowing down from the gap S contains dissolved organic acids that had adhered to the surface of the pipe 331. In this way, the gap S is cleaned. The condensed water that flows down from the gap S is discharged to the outside through a drain hose (not shown). Note that the condensed water is not limited to the gap S between the pipe 331 and the fin 332, but is also generated on the entire surface of the fin 332. Therefore, the generated condensed water can wash away not only organic acids adhering to the surface of the fin 332, but also dust, mold spores, and the like. Here, in the cleaning mode, it is preferable to generate a large amount of condensed water in a short time in order to efficiently and effectively clean the gap S. In an embodiment of the present disclosure, it is preferable to perform cleaning operation in the cleaning mode so that, for example, 1.2 L (liters) or more of condensed water is obtained.

[0025] Furthermore, the operation control unit 43 changes the start conditions for the antifrost operation while the cleaning mode is being executed. When the heat exchanger temperature detected by the temperature detection unit 37 becomes equal to or lower than a preset second threshold while the cleaning mode is being executed, the operation control unit 43 transitions to the antifrost mode. Here, the second threshold is set lower than the first threshold. The second threshold can be set to, for example, 3°C. When the heat exchanger temperature detected by the heat exchanger temperature sensor 37 becomes equal to or lower than 3°C while the cleaning mode is being executed, the operation control unit 43 transitions to the antifrost mode and starts the antifrost operation by reducing the rotation speed of the compressor 21. When the heat exchanger temperature detected by the heat exchanger temperature sensor 37 becomes higher than, for example, 6°C (hereinafter, this may be referred to as the fourth threshold), after the start of the antifrost operation, the operation control unit 43 restores the rotation speed of the compressor 21 to the original rotation speed and ends the antifrost operation. The fourth threshold value, which is the termination condition for the antifrost operation performed while the cleaning mode is being executed, is set to a temperature lower than the third threshold value, which is the termination condition for the antifrost operation in the normal antifrost mode that is executed when the cleaning mode is not being executed.

[0026] Furthermore, in the cleaning mode, the operation control unit 43 executes a drying operation to dry the indoor heat exchanger 33 after the cleaning operation is completed.

[0027] (Procedure for controlling air conditioning equipment) As shown in Figures 5 and 6, after the control device 4 starts cooling operation (or dehumidifying operation) (step S11), the information acquisition unit 41 acquires information on the temperature of the indoor heat exchanger 33 detected by the heat exchanger temperature sensor 37 at predetermined time intervals (step S12).

[0028] The operation control unit 43 determines whether the conditions for starting the antifrost operation are satisfied based on the heat exchanger temperature of the indoor heat exchanger 33 acquired in step S12 (step S13). As a result, if the heat exchanger temperature is equal to or lower than a preset first threshold value (for example, 5°C) (step S13: Yes), the operation control unit 43 determines that the conditions for starting the antifrost operation are satisfied, and transitions to the antifrost mode. In the anti-frost mode, the operation control unit 43 performs the anti-frost operation by reducing the rotation speed of the compressor 21 (step S14). By reducing the rotation speed of the compressor 21, the flow rate of the heat medium sent to the indoor heat exchanger 33 decreases, and the temperature of the indoor heat exchanger 33 increases. This suppresses the formation of frost on the indoor heat exchanger 33.

[0029] After the antifrost operation is started, the operation control unit 43 checks whether the termination condition for the antifrost operation is satisfied (step S15). In step S15, if the heat exchanger temperature detected by the heat exchanger temperature sensor 37 becomes higher than a preset third threshold value (e.g., 8°C), it is determined that the termination condition for the antifrost operation is satisfied. If the termination condition for the antifrost operation is satisfied (step S15: Yes), the rotation speed of the compressor 21 is restored to the original rotation speed, and the antifrost operation is terminated (step S16). On the other hand, if the heat exchanger temperature detected by the heat exchanger temperature sensor 37 is not higher than the preset third threshold value (e.g., 8°C) in step S15 (step S15: No), the antifrost operation is continued.

[0030] If the operation control unit 43 determines in step S13 that the conditions for starting antifrost operation are not satisfied (step S13: No), the operation control unit 43 determines whether or not a signal to terminate cooling operation (or dehumidification operation) has been received from a remote controller (not shown) or the like (step S17). As a result, if a signal to end the cooling operation (or dehumidifying operation) has not been received (step S17: No), the process returns to step S12 and continues. Also, in step S17, if it is determined that a signal to terminate cooling operation (or dehumidifying operation) has been received (step S17: Yes), the operation control unit 43 terminates the cooling operation (or dehumidifying operation) of the indoor unit 3 (step S18).

[0031] As shown in Fig. 6, after the cooling operation (or dehumidifying operation) of the indoor unit 3 is completed, the dew point temperature in the space in which the indoor unit 3 is installed at that time is acquired (step S19). An information acquisition unit 41 acquires information on the heat exchanger temperature detected by the heat exchanger temperature sensor 37 and the humidity detected by the humidity sensor 38 at preset time intervals. Then, a dew point temperature calculation unit 42 calculates the dew point temperature in the room where the indoor unit 3 is installed based on the heat exchanger temperature and humidity.

[0032] Next, the operation control unit 43 determines whether or not a preset condition for starting a cleaning operation is satisfied (step S20). The cleaning operation is performed when the heat exchanger temperature of the indoor heat exchanger 33 is higher than the dew point temperature at the time after the cooling operation or dehumidification operation performed by the indoor unit 3 has ended. Therefore, in step S20, the operation control unit 43 determines whether or not the heat exchanger temperature of the indoor heat exchanger 33 is higher than the calculated dew point temperature. If the heat exchanger temperature is higher than the dew point temperature in step S20, the operation control unit 43 determines that the condition for starting a cleaning operation is satisfied (step S20: Yes), and proceeds to step S23.

[0033] Furthermore, if the heat exchanger temperature is lower than the calculated dew point temperature and the start condition for the cleaning operation is not satisfied (step S20: No), the operation control unit 43 further checks whether the rotation speed (frequency) of the compressor 21 at the end of the cooling operation (or dehumidifying operation) is higher than a preset threshold. The operation control unit 43 also checks whether the duration of the cooling operation (or dehumidifying operation) until the cooling operation (or dehumidifying operation) is terminated is longer than a preset threshold. If the rotation speed (frequency) of the compressor 21 at the end of the cooling operation (or dehumidifying operation) is higher than the preset threshold and the duration of the cooling operation (or dehumidifying operation) is longer than the preset threshold, the operation control unit 43 determines that sufficient condensation has occurred in the indoor heat exchanger 33. In this case, the operation control unit 43 activates the fan 34 and opens the louver 35 to cause the indoor unit 3 to perform a fan operation (step S21). After starting step S21, the operation control unit 43 determines whether or not the conditions for ending the fan operation are satisfied (step S22). If a preset time has not elapsed since the start of the fan operation (step S22: No), the operation control unit 43 continues the fan operation. If a preset time has elapsed since the start of the fan operation, the operation control unit 43 determines that the conditions for ending the fan operation are satisfied (step S22: Yes), and ends the fan operation.

[0034] In step S20, the operation control unit 43 determines that the start condition for the cleaning operation is satisfied if the rotation speed (frequency) of the compressor 21 at the end of the cooling operation (or dehumidifying operation) is lower than a preset threshold, even if the heat exchanger temperature is lower than the calculated dew point temperature. Also, the operation control unit 43 determines that the start condition for the cleaning operation is satisfied if the duration of the cooling operation (or dehumidifying operation) until the cooling operation (or dehumidifying operation) is terminated is shorter than a preset time threshold, even if the heat exchanger temperature is lower than the calculated dew point temperature. In step S20, if the operation control unit 43 determines that the start conditions for the cleaning operation are satisfied (step S20: Yes), the process proceeds to step S23.

[0035] In step S23, the operation control unit 43 transitions to cleaning mode and causes the indoor unit 3 to perform cleaning operation. In cleaning mode, the operation control unit 43 cools the indoor heat exchanger 33 to create a state in which condensation is likely to occur inside the housing 31. To achieve this, the operation control unit 43 increases the rotation speed of the compressor 21, for example. The operation control unit 43 may also increase the rotation speed of the fan 34. The operation control unit 43 may also reduce the opening degree of the louvers 35. The operation control unit 43 may also extend the duration of the cleaning operation. When the indoor heat exchanger 33 is cooled in this way, condensation water is generated in the gap S between the pipe 331 and the fins 332, and this condensation water cleans the gap S.

[0036] Furthermore, in step S23, the start conditions of the antifrost operation for transitioning to the antifrost operation are changed while the indoor unit 3 is performing the cleaning operation in the cleaning mode. Specifically, the operation control unit 43 changes the start conditions of the antifrost operation so that the indoor unit 3 performs the antifrost operation when the heat exchanger temperature detected by the temperature detection unit 37 becomes equal to or lower than a second threshold value (for example, 3°C) that is set lower than the first threshold value while the indoor unit 3 is performing the cleaning operation in the cleaning mode.

[0037] Thereafter, while the indoor unit 3 is performing cleaning operation in cleaning mode, the information acquisition unit 41 acquires information on the temperature of the indoor heat exchanger 33 detected by the heat exchanger temperature sensor 37 at preset time intervals (step S24). The operation control unit 43 determines whether the conditions for starting the antifrost operation are satisfied based on the heat exchanger temperature of the indoor heat exchanger 33 acquired in step S24 (step S25). As a result, if the heat exchanger temperature is equal to or lower than a second preset threshold value (for example, 3°C) (step S25: Yes), the operation control unit 43 determines that the conditions for starting the antifrost operation are satisfied, and transitions to the antifrost mode. In the anti-frost mode, the operation control unit 43 performs the anti-frost operation by reducing the rotation speed of the compressor 21 (step S26). By reducing the rotation speed of the compressor 21, the flow rate of the heat medium sent to the indoor heat exchanger 33 decreases, and the temperature of the indoor heat exchanger 33 increases. This suppresses the formation of frost on the indoor heat exchanger 33.

[0038] After the antifrost operation is started, the operation control unit 43 checks whether the termination condition for the antifrost operation is satisfied (step S27). In step S27, if the heat exchanger temperature detected by the heat exchanger temperature sensor 37 becomes higher than a fourth preset threshold value (for example, 6°C), it is determined that the termination condition for the antifrost operation is satisfied. If the termination condition for the antifrost operation is satisfied (step S27: Yes), the rotation speed of the compressor 21 is restored to the original rotation speed, and the antifrost operation is terminated (step S28). On the other hand, if the heat exchanger temperature detected by the heat exchanger temperature sensor 37 is not higher than the fourth preset threshold value (for example, 6°C) in step S27 (step S27: No), the antifrost operation is continued.

[0039] In step S25, if the operation control unit 43 determines that the conditions for starting the antifrost operation are not satisfied (step S25: No), the operation control unit 43 determines whether the predetermined conditions for terminating the cleaning operation are satisfied (step S29). The operation control unit 43 determines, as a termination condition for the cleaning operation, for example, whether the heat exchanger temperature of the indoor heat exchanger 33 is lower than the dew point temperature at that time. If the heat exchanger temperature of the indoor heat exchanger 33 is not lower than the dew point temperature at that time, the operation control unit 43 determines that the termination condition for the cleaning operation is not satisfied (step S29: No), and returns to step S24 to repeat the process. Furthermore, if the heat exchanger temperature of the indoor heat exchanger 33 is lower than the dew point temperature at that time, the operation control unit 43 determines that the end condition for the cleaning operation is satisfied (step S29: Yes), and proceeds to step S30.

[0040] In step S30, the operation control unit 43 executes a drying operation to dry the indoor heat exchanger 33. Specifically, the operation control unit 43 switches the indoor unit 3 to heating operation. This increases the temperature of the indoor heat exchanger 33, and condensation adhering to the indoor heat exchanger 33 evaporates. This drying operation is carried out so that the temperature of the indoor heat exchanger 33 becomes less than 40°C. When this drying operation has continued for a preset time or longer, the operation control unit 43 determines that the conditions for terminating the drying operation have been satisfied (step S31), and ends the drying operation, thereby terminating the operation of the air conditioner 1.

[0041] (Action and effect) The air conditioner 1 and control method for the air conditioner 1 configured as described above can execute a cleaning mode in which the indoor heat exchanger 33 is cooled to generate condensation water in the gap S between the pipe 331 and the fins 332, and the condensation water is used to clean the gap S. As a result, even if organic acids such as formic acid and acetic acid contained in air fresheners used indoors or wallpaper adhesives get into the gap S between the pipe 331 and the fins 332, the condensation water generated during cleaning operation can be used to clean the gap S, thereby preventing the organic acids from adhering to the pipe 331. Furthermore, in the cleaning mode, the indoor unit 3 is made to perform anti-frost operation when the heat exchanger temperature falls to or below a second threshold value that is set lower than the first threshold value. As a result, compared to the normal anti-frost mode in which the indoor unit 3 is made to perform anti-frost operation when the heat exchanger temperature falls below the first threshold value, it is more difficult to switch to anti-frost operation when the cleaning mode is being performed. This allows the cleaning operation to continue for a longer period of time. As a result, the effect of inhibiting corrosion of the pipe 331 by the organic acid can be sufficiently obtained.

[0042] Furthermore, in the air conditioning device 1, after the cleaning mode is executed, a drying operation is executed to dry the indoor heat exchanger 33, thereby preventing condensation water from remaining in the gap S between the pipe 331 and the fin 332, and in this respect, corrosion of the pipe 331 due to organic acids can also be effectively suppressed.

[0043] Furthermore, when the air conditioner 1 executes the cleaning mode, at least one of the rotation speed of the compressor 21, the rotation speed of the fan 34, the opening degree of the louvers 35, and the duration of the cleaning operation is set to a preset condition. This allows the indoor heat exchanger 33 to be cooled efficiently, and the gap S between the pipe 331 and the fins 332 to be cleaned well by the condensed water that forms in the gap S.

[0044] (Modification of the embodiment) In the above embodiment, the procedure of the control method for the air conditioner 1 is shown, but the order and the conditions for making various determinations can be changed as appropriate. Furthermore, the cleaning operation of the indoor heat exchanger 33 in the cleaning mode can also be performed at an appropriate timing by operating a remote controller, for example.

[0045] Alternatively, a program for implementing all or part of the functions of the control device 4 may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed to perform processing by each functional unit. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. Furthermore, if a WWW system is used, the term "computer system" also includes the homepage provision environment (or display environment). Furthermore, the term "computer-readable recording medium" refers to portable media such as CDs, DVDs, and USBs, as well as storage devices such as hard disks built into the computer system. Furthermore, if the program is distributed to the control device 4 via a communication line, the control device 4 may deploy the program in storage and execute the above-described processing. Furthermore, the program may be for implementing part of the above-described functions, or may be capable of implementing the above-described functions in combination with a program already stored in the computer system.

[0046] <Additional Notes> The air conditioner 1 and the method for controlling the air conditioner 1 described in the embodiment can be understood, for example, as follows.

[0047] (1) An air conditioner 1 according to a first aspect is an air conditioner 1 including an outdoor unit 2 and an indoor unit 3, and is provided with an indoor heat exchanger 33 that is provided in the indoor unit 3 and includes a pipe 331 through which a heat medium supplied from the outdoor unit 2 flows and fins 332 provided around the pipe 331, a dew point temperature calculation unit 42 that calculates a dew point temperature in the room, a temperature detection unit 37 that detects a heat exchanger temperature of the indoor heat exchanger 33, and a control device 4, and when the heat exchanger temperature detected by the temperature detection unit 37 becomes equal to or lower than a predetermined first threshold value, the control device 4 increases the temperature of the indoor heat exchanger 33 to reduce the temperature of the indoor heat exchanger 33 to a level lower than the previous level. The control unit 300 can execute an anti-frost mode in which the indoor unit 3 performs anti-frost operation, and a cleaning mode in which, when the heat exchanger temperature detected by the temperature detection unit 37 is higher than the dew point temperature calculated by the dew point temperature calculation unit 42, the indoor heat exchanger 33 is cooled to produce condensation water in the gap S between the pipe 331 and the fin 332, and a cleaning operation is executed to clean the gap S with the condensation water. In the cleaning mode, when the heat exchanger temperature detected by the temperature detection unit 37 becomes equal to or lower than a second threshold value that is set lower than the first threshold value, the indoor unit 3 is caused to perform anti-frost operation.

[0048] This air conditioner 1 can execute a cleaning mode in which the indoor heat exchanger 33 is cooled to generate condensation water in the gap S between the pipe 331 and the fin 332, and the condensation water is used to clean the gap S. As a result, even if organic acids such as formic acid and acetic acid contained in air fresheners used indoors or wallpaper adhesives get into the gap S between the pipe 331 and the fin 332, the condensation water generated during the cleaning operation can be used to clean the gap S, thereby preventing the organic acids from adhering to the pipe 331. Furthermore, in the cleaning mode, the indoor unit 3 is made to perform anti-frost operation when the heat exchanger temperature falls to or below a second threshold value that is set lower than the first threshold value. As a result, compared to the normal anti-frost mode in which the indoor unit 3 is made to perform anti-frost operation when the heat exchanger temperature falls below the first threshold value, it is more difficult to switch to anti-frost operation when the cleaning mode is being performed. This allows the cleaning operation to continue for a longer period of time. As a result, the effect of inhibiting corrosion of the pipe 331 by the organic acid can be sufficiently obtained.

[0049] (2) The air conditioning apparatus 1 according to the second aspect is the air conditioning apparatus 1 of (1), wherein the control device 4 is further capable of executing a drying mode in which, after executing the cleaning mode, the indoor unit 3 performs a drying operation to dry the indoor heat exchanger 33.

[0050] As a result, after the cleaning mode is executed, a drying operation is performed to dry the indoor heat exchanger 33, thereby preventing condensation water from remaining in the gap S between the pipe 331 and the fin 332, and in this respect, corrosion of the pipe 331 due to organic acids can also be effectively suppressed.

[0051] (3) The air conditioning apparatus 1 according to the third aspect is the air conditioning apparatus 1 according to (1) or (2), and when the control device 4 executes the cleaning mode, it sets at least one of the following to a preset condition: the rotation speed of the compressor 21 that pressurizes the heat medium into the piping 331; the rotation speed of the fan 34 that blows air to the indoor heat exchanger 33; the opening degree of the louver 35 provided at the air outlet that blows the air generated by the fan 34 from the indoor unit 3; and the duration of the cleaning operation.

[0052] As a result, when the cleaning mode is executed, at least one of the rotation speed of the compressor 21, the rotation speed of the fan 34, the opening degree of the louvers 35, and the duration of the cleaning operation is set to a preset condition. This allows the indoor heat exchanger 33 to be cooled efficiently, and the gap S between the pipe 331 and the fins 332 to be effectively cleaned by the condensed water that forms in the gap S.

[0053] (4) A control method for an air conditioner 1 according to a fourth aspect is a control method for an air conditioner 1 including an outdoor unit 2 and an indoor unit 3, and includes step S19 of calculating an indoor dew point temperature, step S12 of detecting a heat exchanger temperature of an indoor heat exchanger 33 of the indoor unit 3, step S14 of increasing the temperature of the indoor heat exchanger 33 to cause the indoor unit 3 to perform anti-frost operation when the heat exchanger temperature becomes equal to or lower than a first threshold value set in advance, and step S52 of calculating a dew point temperature of the indoor unit 3 by calculating a dew point temperature of the indoor unit 3. and step S23 of executing a cleaning operation in which, if the heat exchanger temperature is higher than the calculated dew point temperature, the indoor heat exchanger 33 is cooled, condensation water is generated in a gap S between a pipe 331 of the indoor heat exchanger 33 through which a heat medium supplied from the outdoor unit 2 flows and fins 332 provided around the pipe 331, and the gap S is cleaned with the condensation water. In step S23 of executing the cleaning operation, if the heat exchanger temperature becomes equal to or lower than a second threshold value set lower than the first threshold value, the indoor unit 3 is caused to perform anti-frost operation.

[0054] This makes it possible to obtain a sufficient effect of suppressing corrosion of the pipe 331 due to organic acids. [Explanation of symbols]

[0055] 1...Air conditioning equipment 2…Outdoor unit 3…Indoor unit 4...Control device 5...Connecting piping 21...Compressor 31...Case 31h…Air outlet 33…Indoor heat exchanger 331...Plumbing 332...Finn 332a...plate-shaped part 332b...Cylindrical part 34...Fan 35...Louver 37...Heat exchanger temperature sensor (temperature detection part) 38...Humidity sensor 41…Information acquisition department 42...Dew point temperature calculation section 43...Operation control unit 44...Output section S...gap

Claims

1. An air conditioning apparatus including an outdoor unit and an indoor unit, an indoor heat exchanger provided in the indoor unit, the indoor heat exchanger including a pipe through which a heat medium supplied from the outdoor unit flows and fins provided around the pipe; a dew point temperature calculation unit that calculates a dew point temperature in the room; a temperature detection unit that detects a heat exchanger temperature of the indoor heat exchanger; a control device; The control device an anti-frost mode in which, when the heat exchanger temperature detected by the temperature detection unit becomes equal to or lower than a first threshold value set in advance, the temperature of the indoor heat exchanger is increased to cause the indoor unit to perform an anti-frost operation; a cleaning mode in which, when the heat exchanger temperature detected by the temperature detection unit is higher than the dew point temperature calculated by the dew point temperature calculation unit, the indoor heat exchanger is cooled to generate condensation water in the gaps between the pipes and the fins, and a cleaning operation is performed to clean the gaps with the condensation water; In the cleaning mode, when the heat exchanger temperature detected by the temperature detection unit becomes equal to or lower than a second threshold value set lower than the first threshold value, the indoor unit is caused to perform anti-frost operation. Air conditioning equipment.

2. The control device After the cleaning mode is executed, a drying mode in which the indoor unit executes a drying operation to dry the indoor heat exchanger can be further executed. The air conditioning apparatus according to claim 1.

3. When executing the cleaning mode, the control device sets at least one of the rotation speed of the compressor that pressurizes the heat medium into the piping, the rotation speed of the fan that sends air to the indoor heat exchanger, the opening degree of a louver provided in an air outlet that sends out the air from the indoor unit by the fan, and the duration of the cleaning operation to a preset condition. The air conditioning apparatus according to claim 1 or 2.

4. A control method for an air conditioning apparatus including an outdoor unit and an indoor unit, calculating a dew point temperature in the room; Detecting a heat exchanger temperature of an indoor heat exchanger of the indoor unit; When the heat exchanger temperature becomes equal to or lower than a predetermined first threshold value, increasing the temperature of the indoor heat exchanger to cause the indoor unit to perform anti-frost operation; and when the heat exchanger temperature is higher than the dew point temperature, performing a cleaning operation to cool the indoor heat exchanger, generate condensation water in a gap between a pipe of the indoor heat exchanger through which the heat medium supplied from the outdoor unit flows and a fin provided around the pipe, and clean the gap with the condensation water, In the step of executing the cleaning operation, when the heat exchanger temperature becomes equal to or lower than a second threshold value that is set lower than the first threshold value, the step of executing the cleaning operation includes causing the indoor unit to execute an anti-frost operation. A method for controlling an air conditioning device.

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