Air conditioner

Abstract

To provide an air conditioner capable of preventing degradation of cleaning efficiency of an indoor heat exchanger in a cleaning operation.SOLUTION: In executing a cooling operation for cleaning, a compressor is kept at a target rotational frequency until a room temperature detected by a temperature sensor becomes an operation switching temperature or less, thus a surface of an indoor heat exchanger is kept at a dew point temperature or less, and dew condensation water is generated on the surface of the indoor heat exchanger so as to perform cleaning. When the room temperature detected by the temperature sensor becomes close to the operation switching temperature, the rotational frequency of the compressor is lowered to be less than a prescribed rotational frequency, so that the temperature of the surface of the indoor heat exchanger becomes higher than the dew point temperature, and a time when the cleaning cannot be performed because no dew condensation water is generated on the surface of the indoor heat exchanger, can be prevented from arising. Thus, degradation of cleaning efficiency of the indoor heat exchanger can be prevented.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an air conditioner capable of performing a cleaning operation for cleaning an indoor heat exchanger in an indoor unit.

Background Art

[0002] Conventionally, in this type of device, a cleaning operation is performed in which dew condensation water is generated on the surface of an indoor heat exchanger in an indoor unit installed indoors by a cleaning cooling operation in which the indoor heat exchanger functions as an evaporator, and the dust adhering to the surface of the indoor heat exchanger is washed away using the dew condensation water. (For example, Patent Document 1)

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 cools the indoor heat exchanger to below the dew point temperature by a cleaning cooling operation, and generates dew condensation water on the surface of the indoor heat exchanger. Therefore, if the temperature of the indoor heat exchanger continues to decrease due to the cleaning cooling operation, the dew condensation water generated in the indoor heat exchanger freezes, and the dust adhering to the surface of the indoor heat exchanger cannot be washed away. To prevent this, a temperature sensor detects the room temperature during the cleaning cooling operation, and when the room temperature detected by the temperature sensor becomes equal to or lower than the operation switching temperature, the cleaning cooling operation is stopped, the switching valve in the refrigerant circuit is switched, and a cleaning heating operation is performed in which the indoor heat exchanger functions as a condenser to raise the room temperature. When the room temperature has risen, the switching valve in the refrigerant circuit is switched, and the cleaning cooling operation in which the indoor heat exchanger functions as an evaporator is restarted. By repeating this control during the cleaning time, it is conceivable to prevent the indoor heat exchanger from freezing during the cleaning operation.

[0005] However, since the heating operation for cleaning in the cleaning operation does not contribute to the cleaning of the indoor heat exchanger, it is desired to shorten the execution time. Therefore, when the room temperature approaches the operation switching temperature during the execution of the cooling operation for cleaning, the rotation speed of the compressor is decreased so as not to reach the operation switching temperature in a short time, and the time of the cooling operation for cleaning is extended. When the rotation speed of the compressor decreases, the temperature of the refrigerant flowing through the indoor heat exchanger rises and the surface temperature of the indoor heat exchanger becomes higher than the dew point temperature, so that condensed water does not occur in the indoor heat exchanger. Despite the execution of the cooling operation for cleaning, there is a time when the indoor heat exchanger cannot be cleaned by the condensed water, the cleaning time of the indoor heat exchanger in the cleaning operation is shortened, and the cleaning efficiency is reduced, so there is room for improvement.

Means for Solving the Problems

[0006] In order to solve the above-described problems, the air conditioner according to the present invention, in claim 1, includes a refrigerant circuit through which a refrigerant circulates and flows, a compressor provided in the refrigerant circuit and having a variable rotation speed, an outdoor heat exchanger provided in the refrigerant circuit and exchanging heat with outdoor air, an expansion valve provided in the refrigerant circuit for reducing the pressure of the refrigerant, an indoor heat exchanger provided in the refrigerant circuit and exchanging heat with indoor air, a switching valve provided in the refrigerant circuit for changing the flow direction of the refrigerant, a temperature sensor for detecting the room temperature, a cooling operation for cleaning for condensing and cleaning the indoor heat exchanger, a heating operation for cleaning for switching the switching valve so that the refrigerant flows through the refrigerant circuit in a direction opposite to the cooling operation for cleaning and raising the room temperature, an operation switching temperature for switching from the cooling operation for cleaning to the heating operation for cleaning, When it is determined that the room temperature detected by the temperature sensor becomes equal to or lower than the operation switching temperature during the execution of the cooling operation for cleaning, switch to the heating operation for cleaning After the implementation of the washing heating operation, if it is determined that the continuous operation time of the washing heating operation has elapsed a predetermined reference time or the detected value by the temperature sensor has reached a predetermined set temperature or higher, switch to the washing cooling operation and alternately perform the washing cooling operation and the washing heating operation and a control unit for controlling the cleaning operation. When the cleaning cooling operation is performed, the control unit maintains the compressor at a predetermined rotational speed or higher until the room temperature detected by the temperature sensor becomes equal to or lower than the operation switching temperature.

Advantages of the Invention

[0009] According to this invention, when the cleaning cooling operation is performed, since the compressor is maintained at a predetermined rotational speed or higher until the temperature becomes equal to or lower than the operation switching temperature, it is possible to prevent the cleaning time of the indoor heat exchanger due to condensed water from being shortened during the cleaning operation, and to prevent a decrease in cleaning efficiency.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0011] An embodiment of the present invention will be described below with reference to the accompanying drawings.

[0012] Figure 1 shows an air conditioner 10 (air conditioner) equipped with a refrigerant circuit 11 through which refrigerant flows inside. The air conditioner 10 has a function of performing a cooling operation for cooling the interior R and a heating operation for heating the interior R. The refrigerant circuit 11 includes an outdoor unit 20 disposed outdoors Ou and an indoor unit 30 disposed indoors R. Hereinafter, unless otherwise specified, the direction in which the refrigerant circulates is based on the cooling operation.

[0013] The outdoor unit 20 includes a switching valve 21 that switches the flow direction of the refrigerant during the cooling operation and the heating operation, a compressor 22 through which the refrigerant that has passed through the switching valve 21 flows and compresses the refrigerant, an outdoor heat exchanger 23 through which the refrigerant compressed to high temperature and high pressure in the compressor 22 flows, a propeller fan 24 that sends outdoor air toward the outdoor heat exchanger 23, and an expansion valve 25 that decompresses the refrigerant that has passed through the outdoor heat exchanger 23.

[0014] The indoor unit 30 is hung on the wall Wa in the interior R. The indoor unit 30 includes an indoor fan 31 that takes in air from the interior and blows air into the interior, an indoor heat exchanger 32 that exchanges heat with the indoor air taken in by the indoor fan 31, and a case 33 that houses the indoor fan 31 and the indoor heat exchanger 32.

[0015] The case 33 has an air outlet 33a that serves as an outlet for the air blown out by the indoor fan 31. At the air outlet 33a, a left - right louver 34 that adjusts the left - right direction of the blown air and an up - down louver 35 that adjusts the up - down direction of the blown air are arranged.

[0016] The cooling operation will be described. The refrigerant made into high temperature and high pressure by the compressor 22 exchanges heat with the outdoor air in the outdoor heat exchanger 23 and releases heat. At this time, when the propeller fan 24 rotates, the outside air is forcibly flowed to the outer periphery of the outdoor heat exchanger 23 to promote heat exchange. The refrigerant that has passed through the outdoor heat exchanger 23 and released heat is decompressed in the expansion valve 25, and the temperature decreases. The refrigerant with the decreased temperature flows to the indoor heat exchanger 32.

[0017] The low-temperature refrigerant flowing into the indoor heat exchanger 32 exchanges heat with the indoor air of the room R in the indoor heat exchanger 32 to cool the air in the room R. The cooled air is blown into the room R by the indoor fan 31. The indoor fan 31 forcibly flows the air around the outer periphery of the indoor heat exchanger 32 to promote heat exchange with the refrigerant.

[0018] During the heating operation, the switching valve 21 switches the refrigerant flow path to circulate the refrigerant in the direction opposite to that during the cooling operation.

[0019] FIG. 2 shows a control block diagram of the air conditioner 10 (see FIG. 1). The indoor unit 30 includes an indoor control unit 40 (control unit) that controls the indoor fan 31, the left and right louvers 34, and the up and down louvers 35, a temperature sensor 41 that detects the indoor temperature, a display lamp 42 that displays the operation status by the indoor control unit 40, and a remote control transceiver unit 43 that exchanges predetermined information with the remote control 12.

[0020] The indoor control unit 40 has a storage unit 44 that stores data received via the remote control transceiver unit 43, detection values of the temperature sensor 41, set temperatures, reference times, and other predetermined programs described later, and a plurality of timers t1 to t4 that measure the elapsed time.

[0021] The outdoor unit 20 has an outdoor control unit 45 that is electrically connected to the indoor control unit 40. The indoor control unit 40 can control the switching valve 21, the compressor 22, the propeller fan 24, and the expansion valve 25 via the outdoor control unit 45.

[0022] The air conditioner 10 also has a function of performing a cleaning operation to clean the dust adhering to the surface of the indoor heat exchanger 32 (see FIG. 1). Hereinafter, the control content of the cleaning operation of the air conditioner 10 will be described.

[0023] Figures 3 and 4 show flowcharts representing the control content of the air conditioner apparatus 10. When a signal to start the cleaning operation is transmitted from the remote controller 12 (see FIG. 2) to the indoor control unit 40, or when predetermined conditions are satisfied after the completion of the cooling operation or the heating operation (for example, a predetermined time has elapsed since the end of the previous cleaning operation), the indoor control unit 40 starts the cleaning operation (start) in a manner indicating that the cleaning operation is being performed on the display lamp 42.

[0024] When the cleaning operation is started, in step St1, the first timer t1 starts from "0". The first timer t1 measures the duration of the cleaning operation.

[0025] In step St2, the indoor control unit 40 acquires the room temperature Tr detected by the temperature sensor 41.

[0026] In step St3, it is determined whether the room temperature Tr is within a predetermined temperature range. Specifically, it is determined whether the room temperature Tr is less than the reference room temperature value Ts1 and greater than or equal to the lowest reference value Ts2 set lower than the reference room temperature value Ts1 (Ts2 ≦ Tr < Ts1). The reference room temperature value Ts1 and the lowest reference value Ts2 are preset values.

[0027] If the room temperature Tr is less than the lowest reference value Ts2 (Tr < Ts2), the cleaning operation ends (end).

[0028] If the room temperature Tr is greater than or equal to the lowest reference value Ts2 and less than the reference room temperature value Ts1 (Ts2 ≦ Tr < Ts1), in step St4, the second timer t2 starts from "0".

[0029] Thereafter, in step St5, a cleaning heating operation for heating the room R is executed. See also FIGS. 1 and 2. The cleaning heating operation is intended to create an environment suitable for condensing the surface of the indoor heat exchanger 32. The cleaning heating operation is executed by the outdoor control unit 45 receiving an instruction from the indoor control unit 40 and controlling the compressor 22, the expansion valve 25, and the switching valve 21 in the same manner as in a normal heating operation.

[0030] The cleaning heating operation is executed based on preset conditions. As such conditions, for example, in the cleaning heating operation, at least a temperature higher than the reference room temperature value Ts1 is set as the set temperature Ts3, and the air volume by the indoor fan 31 is maximized. The upper and lower louvers 35 and the left and right louvers 34 are fixed at the positions at the maximum air volume.

[0031] In step St6, the indoor control unit 40 acquires the room temperature Tr detected by the temperature sensor 41.

[0032] In step St7, it is determined whether the room temperature Tr has reached a predetermined set temperature Ts3 by the cleaning heating operation (Tr ≧ Ts3).

[0033] When the room temperature Tr has reached the set temperature Ts3 (Tr ≧ Ts3), in step St8, the third timer t3 is started from "0".

[0034] Thereafter, in step St9, a cleaning cooling operation for generating condensed water on the surface of the indoor heat exchanger 32 due to condensation is executed. The condensed water generated due to condensation washes away the dust adhering to the surface of the indoor heat exchanger 32. The cleaning cooling operation is executed in the same manner as a normal cooling operation, in which the outdoor control unit 45 that has received a command from the indoor control unit 40 controls the compressor 22, the expansion valve 25, and the switching valve 21.

[0035] The cleaning cooling operation is executed based on preset conditions. For example, the set temperature Ts4 of the cleaning cooling operation is a predetermined temperature (for example, the minimum reference value Ts2), and the left and right louvers 34 and the upper and lower louvers 35 are fixed at the positions at the maximum air volume. The air volume is appropriately changed according to the room temperature Tr. And the set temperature Ts4 is the operation switching temperature for switching from the cleaning cooling operation to the cleaning heating operation.

[0036] In addition, the cleaning cooling operation is controlled by the indoor control unit 40 so that when a preset first predetermined time has elapsed, the compressor 22 is stopped and the blowing operation in which only the indoor fan 31 is driven is performed for a preset second predetermined time. The first predetermined time is set to be longer than the second predetermined time. The indoor control unit 40 controls so that the cooling operation and the blowing operation are repeatedly performed until the end condition of the cleaning cooling operation is satisfied. By performing the blowing operation, the humidity in the room can be increased by returning the moisture accumulated in the indoor unit 30 to the indoor R, and the amount of condensed water generated by the cleaning cooling operation can be increased to improve the cleaning efficiency of the indoor heat exchanger 32. The detailed control content during the cleaning cooling operation will be described later.

[0037] In step St7, when the room temperature Tr has not reached the set temperature Ts3 (Tr < Ts3), in step St10, it is determined whether the measurement time by the second timer t2 (the duration of the cleaning heating operation) has elapsed a preset predetermined reference time m1 (the first reference time) (t2 > m1).

[0038] When the measurement time by the second timer t2 has elapsed the reference time m1 (t2 > m1), the third timer t3 is started from "0" (step St8), and then the cleaning cooling operation is executed (step St9).

[0039] When the measurement time by the second timer t2 has not elapsed the reference time m1 (t2 < m1), the cleaning heating operation is continued.

[0040] In step St3, when the room temperature Tr exceeds the reference room temperature value Ts1 (Tr > Ts1), the indoor control unit 40 determines that the indoor R is already in an environment suitable for condensing the surface of the indoor heat exchanger 32. Therefore, the indoor control unit 40 starts the third timer (step St8) without performing the cleaning heating operation (step St5) and executes the cleaning cooling operation (step St9).

[0041] After the start of the cleaning cooling operation in step St9, in step St11, the indoor control unit 40 acquires the room temperature Tr detected by the temperature sensor 41.

[0042] Thereafter, in step St12, it is determined whether the room temperature Tr has become equal to or lower than the set temperature Ts4, which is the operation switching temperature of the cleaning cooling operation (Tr ≦ Ts4).

[0043] When the room temperature Tr becomes equal to or lower than the set temperature Ts4 (Tr ≦ Ts4), in step St13, it is determined whether the measurement time by the first timer t1 (the continuous time of the cleaning operation) has elapsed the preset reference time m2 (the second reference time) (t1 > m2).

[0044] When the measurement time by the first timer t1 has not elapsed the reference time m2 (t1≦ m2), the cleaning cooling operation is stopped, the second timer t2 is reset and then restarted (step St4), and the cleaning heating operation is executed again (step St5). If the cleaning cooling operation continues, the temperature of the refrigerant flowing through the indoor heat exchanger 32 continues to drop, and the condensed water adhering to the surface of the indoor heat exchanger 32 may freeze. When the condensed water freezes, the dust adhering to the surface of the indoor heat exchanger 32 cannot be washed away by the condensed water, and the cleaning efficiency in the cleaning operation decreases. During the cleaning cooling operation, when the room temperature Tr detected by the temperature sensor 41 becomes equal to or lower than the set temperature Ts4 and the reference time m2 has not elapsed, the cleaning heating operation is restarted to raise the room temperature. By raising the surface temperature of the indoor heat exchanger 32, freezing of the condensed water is prevented, and a decrease in the cleaning efficiency in the cleaning operation is blocked.

[0045] In step St13, when the measurement time by the first timer t1 (the continuous time of the cleaning operation) has elapsed the reference time m2 (t1> m2), or in step St12, when the room temperature Tr becomes equal to or higher than the set temperature Ts4 (Tr ≧ Ts4), in step St14, it is determined whether the measurement time by the third timer t3 (the continuous time of the cleaning cooling operation) has elapsed the preset reference time m3 (t3 > m3).

[0046] When the measurement time by the third timer has elapsed the reference time in step St14 (t3 > m3), in step St15, the fourth timer t4 is started from "0".

[0047] Thereafter, in step St16, a cleaning and drying operation for drying the indoor heat exchanger 32 is started. The cleaning and drying operation is executed by the outdoor control unit 45 receiving a command from the indoor control unit 40 and controlling the compressor 22, the expansion valve 25, and the switching valve 21, in the same manner as a normal heating operation.

[0048] The cleaning and drying operation is executed based on preset conditions. For example, the set temperature Ts6 (not shown) of the cleaning and drying operation is set to a predetermined temperature. The hot start function for preventing the blowing of cold air at the start of the heating operation and the defrosting operation function for warming the outdoor heat exchanger 23 to melt frost are disabled. The upper and lower louvers 35 and the left and right louvers 34 are fixed at the positions when the air volume is maximum. The air volume is appropriately changed according to the room temperature Tr.

[0049] If the measurement time by the third timer t3 (the duration of the cleaning and cooling operation) has not elapsed the reference time m3 in step St14 (t3 ≦ m3), in step St17, it is determined whether the measurement time by the first timer t1 (the duration of the cleaning operation) has elapsed the preset reference time m4 (t1 > m4).

[0050] If the measurement time by the first timer t1 (the duration of the cleaning operation) has not elapsed the reference time m4 (t1 ≦ m4), the cleaning and cooling operation (step St9) is continued.

[0051] If the measurement time by the first timer t1 (the duration of the cleaning operation) has elapsed the reference time m4 (t1 > m4), the fourth timer t4 is started from "0" (step St15), and then the cleaning and drying operation is started (step St16).

[0052] After the start of the drying operation for cleaning in step St16, in step St18, it is determined whether the measurement time by the fourth timer t4 (the duration of the drying operation for cleaning) has elapsed the preset reference time m5 (t4 > m5).

[0053] If the measurement time by the fourth timer t4 (the duration of the drying operation for cleaning) has not elapsed the preset reference time m5 (t4 ≤ m5), the drying operation for cleaning is continued.

[0054] When the measurement time by the fourth timer t4 has elapsed the preset reference time m5 (t4 > m5), the indoor control unit 40 ends the cleaning operation (END). When ending the cleaning operation, the indoor control unit 40 turns off the display lamp 42 provided in the indoor unit 30, and performs the processing at the time of stopping the operation for the upper and lower louvers 35 and the left and right louvers 34.

[0055] Next, the switching control between the heating operation for cleaning and the cooling operation for cleaning in the cleaning operation in this embodiment will be described in detail.

[0056] First, a comparative example of the present invention will be described with reference to FIG. 5. When an instruction to start the cleaning operation is issued, the room temperature Tr detected by the temperature sensor 41 is equal to or higher than the lowest reference value Ts2 and is the reference room temperature value Ts1, and the heating operation for cleaning in step St5 is performed. During the heating operation for cleaning, the compressor 22 is maintained at a preset target rotation speed until the end condition of the heating operation for cleaning is satisfied.

[0057] Thereafter, when the room temperature Tr detected by the temperature sensor 41 becomes equal to or higher than the set temperature Ts within the reference time m1 from the start of the heating operation for cleaning, it is assumed that the end condition of the heating operation for cleaning is satisfied, the compressor 22 is stopped, and the switching valve 21 is driven to switch to the refrigerant circuit 11 in which the refrigerant flows so that the indoor heat exchanger 32 functions as an evaporator. When the preparation is completed, the compressor 22 is driven to start the cooling operation for cleaning. During the cooling operation for cleaning, the rotation speed of the compressor 22 is maintained at the target rotation speed until it approaches the operation switching temperature for switching to the heating operation for cleaning.

[0058] After the start of the cleaning cooling operation, when the indoor control unit 40 determines that the operating time of the cleaning cooling operation is equal to or longer than a first predetermined time without satisfying the end condition of the cleaning cooling operation, the indoor control unit 40 stops the compressor 22 and performs a blowing operation in which only the indoor fan 31 is driven. During the blowing operation, since low-temperature refrigerant does not flow through the indoor heat exchanger 32, the indoor heat exchanger 32 is not cleaned by condensed water. By performing the blowing operation, the moisture accumulated around the indoor heat exchanger 32 is returned to the room, increasing the room humidity, and thus the amount of condensed water generated in the indoor heat exchanger 32 during the cleaning cooling operation can be increased. The performance of the blowing operation is particularly suitable when the room is in a low humidity state.

[0059] After switching from the cleaning cooling operation to the blowing operation, the indoor control unit 40 continues the blowing operation for a second predetermined time. If the end condition of the cleaning cooling operation is not satisfied, the indoor control unit 40 drives the compressor 22 and starts the cleaning cooling operation again. Note that the second predetermined time is shorter than the first predetermined time.

[0060] During the cleaning cooling operation here, when the room temperature Tr detected by the temperature sensor 41 becomes equal to or lower than a predetermined start temperature Td1 close to the operation switching temperature, the indoor control unit 40 decreases the rotational speed of the compressor 22 from the target rotational speed to a rotational speed X1 decreased by a predetermined value. Thereafter, when the room temperature further decreases and the room temperature Tr detected by the temperature sensor 41 becomes lower than the predetermined start temperature Td1 and equal to or lower than a predetermined start temperature Td2 higher than the operation switching temperature, the indoor control unit 40 decreases the rotational speed of the compressor 22 to a rotational speed X2 lower than the rotational speed X1 (section (A)).

[0061] The cleaning cooling operation with the rotational speeds X1 and X2 of the compressor 22 has lower capacity compared to the cleaning cooling operation in which the compressor 22 is driven at the target rotational speed, the temperature of the refrigerant flowing through the indoor heat exchanger 32 becomes higher, and the surface temperature of the indoor heat exchanger 32 becomes higher than the dew point temperature. When the surface temperature of the indoor heat exchanger 32 becomes higher than the dew point temperature, no condensed water is generated on the surface of the indoor heat exchanger 32, and this is the cleaning cooling operation time during which the indoor heat exchanger 32 is not cleaned.

[0062] Thereafter, when the indoor control unit 40 determines that the room temperature Tr detected by the temperature sensor 41 becomes equal to or lower than the set temperature Ts4 which is the operation switching temperature and the termination condition of the cleaning cooling operation is satisfied within the continuous time of the cleaning operation, the compressor 22 is stopped, and the switching valve 21 is driven to switch to the refrigerant circuit 11 in which the refrigerant flows so that the indoor heat exchanger 32 functions as a condenser. When the preparation is completed, the cleaning heating operation is performed again.

[0063] As described above, when the control is performed to reduce the rotational speed of the compressor 22 when the room temperature Tr detected by the temperature sensor 41 approaches the operation switching temperature and becomes equal to or lower than the predetermined decrease start temperature during the cleaning cooling operation, there is a time when dew condensation water does not occur on the surface of the indoor heat exchanger 32 in the cleaning cooling operation. Since the upper limit of the execution time of the cleaning operation is set in advance, in other words, the cleaning cooling operation time when dew condensation water does not occur becomes a factor for reducing the cleaning efficiency of the indoor heat exchanger 32.

[0064] Next, an embodiment of the present invention will be described with reference to FIG. 6. Note that the switching from the start instruction of the cleaning operation to the cleaning heating operation, the cleaning cooling operation, and the blowing operation is the same as in the comparative example, and thus the description thereof is omitted.

[0065] In the present embodiment, the predetermined decrease start temperature Td1 described in the comparative example is used as the operation switching temperature. Therefore, during the cleaning cooling operation, the indoor control unit 40 does not reduce the rotational speed of the compressor 22 even when the room temperature detected by the temperature sensor 41 approaches the operation switching temperature, and drives the compressor 22 while maintaining the rotational speed at a target rotational speed equal to or higher than the predetermined rotational speed (section (B)). As a result, even when the room temperature detected by the temperature sensor 41 approaches the operation switching temperature, the temperature of the refrigerant flowing through the indoor heat exchanger 32 does not increase. The surface of the indoor heat exchanger 32 can be maintained below the dew point temperature, and dew condensation water can be continuously generated on the surface of the indoor heat exchanger 32 for cleaning.

[0066] In addition, since the rotational speed of the compressor 22 does not decrease even when the room temperature detected by the temperature sensor 41 approaches the operation switching temperature, the ability does not decrease, so the room temperature detected by the temperature sensor 41 becomes below the operation switching temperature earlier than in the comparative example. As a result, the heating operation for cleaning and the cooling operation for cleaning are carried out at a time earlier than in the comparative example. Therefore, if the environmental conditions are the same within the upper limit time during which the cleaning operation can be carried out, the embodiment has a longer operation time for the cooling operation for cleaning than the comparative example. The time for generating condensed water on the surface of the indoor heat exchanger 32 and cleaning the indoor heat exchanger 32 becomes longer than in the comparative example, and the cleaning efficiency is improved.

[0067] In the present embodiment, a predetermined decrease start temperature Td1 is used as the operation switching temperature, but a predetermined decrease start temperature Td2 may be used as the operation switching temperature. During the cooling operation for cleaning, the compressor 22 is maintained at a target rotational speed equal to or higher than a predetermined rotational speed until the room temperature detected by the temperature sensor 41 becomes equal to or lower than the predetermined decrease start temperature Td2. During the implementation of the cooling operation for cleaning, the surface temperature of the indoor heat exchanger 32 can be made equal to or lower than the dew point temperature, and the cleaning efficiency of the indoor heat exchanger 32 by the condensed water is improved.

[0068] In addition, in the present embodiment, during the cooling operation for cleaning, the description has been made in terms of maintaining the compressor 22 at the target rotational speed until it becomes below the operation switching temperature, but it is not limited to this. During the cooling operation for cleaning, the surface of the indoor heat exchanger 32 is maintained at a temperature equal to or lower than the dew point temperature, and the rotational speed of the compressor 22 capable of generating condensed water on the surface of the indoor heat exchanger 32 and cleaning it is equal to or higher than a predetermined rotational speed. Therefore, when approaching the operation switching temperature during the cleaning cooling operation, even if the rotational speed of the compressor 22 is changed to a rotational speed other than the target rotational speed, if it is controlled to maintain a rotational speed equal to or higher than a predetermined rotational speed for the changed rotational speed, it is within the scope of the present invention.

[0069] Next, the effects of the present invention will be described.

[0070] When performing the cleaning cooling operation to generate condensed water on the surface of the indoor heat exchanger 32 and clean the surface of the indoor heat exchanger 32, the compressor 22 is maintained at a target rotation speed that is equal to or higher than a predetermined rotation speed until the room temperature detected by the temperature sensor 41 becomes equal to or lower than the operation switching temperature. By maintaining the compressor 22 at the target rotation speed until the room temperature detected by the temperature sensor 41 becomes equal to or lower than the operation switching temperature during the cleaning cooling operation, the surface of the indoor heat exchanger 32 can be maintained at a temperature equal to or lower than the dew point temperature, and condensed water can be generated on the surface of the indoor heat exchanger 32 for cleaning. When the room temperature detected by the temperature sensor 41 approaches the operation switching temperature, by reducing the rotation speed of the compressor 22 to less than the predetermined rotation speed, it is possible to prevent the surface of the indoor heat exchanger 32 from becoming higher than the dew point temperature and prevent the occurrence of a period during which condensed water cannot be generated on the surface of the indoor heat exchanger 32 and cleaning cannot be performed. Thereby, a decrease in the cleaning efficiency of the indoor heat exchanger 32 can be prevented.

[0071] Also, the predetermined decrease start temperature at which the rotation speed of the compressor 22 is decreased during the cleaning cooling operation is set as the operation switching temperature. During the cleaning cooling operation, the rotation speed of the compressor 22 can be maintained at a predetermined rotation speed or higher until switching to the cleaning heating operation. The surface of the indoor heat exchanger 32 can be maintained at a temperature equal to or lower than the dew point temperature, and condensed water can be generated on the surface of the indoor heat exchanger 32 for cleaning.

[0072] Also, after performing the cleaning heating operation, when the indoor control unit 40 determines that the elapsed time of the cleaning heating operation has exceeded a predetermined reference time m1 or the detected value by the temperature sensor 41 has become equal to or higher than a predetermined set temperature Ts3, it switches to the cleaning cooling operation. Since the room temperature is increased by the cleaning heating operation and the amount of condensed water generated on the surface of the indoor heat exchanger 32 is increased by the cleaning cooling operation, a decrease in the cleaning efficiency of the indoor heat exchanger 32 can be prevented.

[0073] Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0074] 10 Air conditioner 11 Refrigerant circuit 21 Switching valve 22 Compressor 23 Outdoor heat exchanger 25 Expansion valve 40 Indoor control unit (control unit) 41 Temperature sensor

Claims

【Claim 1】 A refrigerant circuit through which a refrigerant circulates and flows, A compressor provided in the refrigerant circuit and having a variable rotational speed, An outdoor heat exchanger provided in the refrigerant circuit for exchanging heat with outdoor air, An expansion valve provided in the refrigerant circuit for reducing the pressure of the refrigerant, An indoor heat exchanger provided in the refrigerant circuit for exchanging heat with indoor air, A switching valve provided in the refrigerant circuit for changing the flow direction of the refrigerant, A temperature sensor for detecting the room temperature, A cleaning cooling operation for condensing and cleaning the indoor heat exchanger, A cleaning heating operation for switching the switching valve so that the refrigerant flows through the refrigerant circuit in a direction opposite to that of the cleaning cooling operation and raising the room temperature, An operation switching temperature for switching from the cleaning cooling operation to the cleaning heating operation, When it is determined that the room temperature detected by the temperature sensor has become equal to or lower than the operation switching temperature during the execution of the cleaning cooling operation, switching to the cleaning heating operation, and after the execution of the cleaning heating operation, when it is determined that the elapsed time of the execution of the cleaning heating operation has passed a predetermined reference time or the detected value by the temperature sensor has become equal to or higher than a predetermined set temperature, switching to the cleaning cooling operation, and a control unit for controlling a cleaning operation in which the cleaning cooling operation and the cleaning heating operation are alternately performed, The control unit maintains the compressor at a predetermined rotational speed or higher until the room temperature detected by the temperature sensor becomes equal to or lower than the operation switching temperature during the execution of the cleaning cooling operation. An air conditioner characterized by this.

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