JPWO2017179192A1 - Air conditioner - Google Patents

Abstract

  The air conditioner has a refrigerant circuit in which a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected via a refrigerant pipe, and an indoor temperature that detects the indoor temperature of the room in which the indoor heat exchanger is installed. A temperature sensor; a pipe temperature sensor that detects a pipe temperature of the indoor heat exchanger; and a control device that controls the compressor based on detection results of the indoor temperature sensor and the pipe temperature sensor. Set the compressor drive frequency using the room temperature and the set temperature detected by the operation temperature, set the target evaporation temperature from the room temperature detected by the room temperature sensor, and the pipe temperature sensor The difference between the pipe temperature and the target evaporation temperature is high in the operation condition determination unit that determines whether or not the difference between the measured pipe temperature and the target evaporation temperature is smaller than the high temperature threshold. If less than the threshold value, and it has a compressor control unit for driving the compressor at a frequency higher than the drive frequency.

Description

  The present invention relates to an air conditioner that performs humidity control.

  When the room temperature and the set temperature are far from each other, the conventional air conditioner first performs a cooling operation based on the temperature difference targeting the set temperature, bringing the room temperature close to the set temperature and setting the room temperature and the set temperature. When the temperature is close, there is one that switches to an operation that targets the evaporation temperature (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 9-14724

  However, the air conditioner of Patent Document 1 switches to an operation aimed at dehumidification after the room temperature reaches the set temperature. At this time, since the humidity is brought close to the target value after the temperature is brought close to the target value, the temperature and humidity cannot be brought close to the target value quickly.

  The present invention has been made to solve the above problems, and provides an air conditioner that can perform comfortable air conditioning by quickly bringing temperature and humidity close to target values.

  An air conditioner according to the present invention includes a compressor, an outdoor heat exchanger, an expansion valve, a refrigerant circuit in which an indoor heat exchanger is connected via a refrigerant pipe, and an indoor temperature in which the indoor heat exchanger is installed. An indoor temperature sensor for detecting the temperature, a pipe temperature sensor for detecting the pipe temperature of the indoor heat exchanger, and a control device for controlling the compressor based on the detection results of the indoor temperature sensor and the pipe temperature sensor. Is configured to set the drive frequency of the compressor using the indoor temperature detected by the indoor temperature sensor and the set temperature, and to set the target evaporation temperature from the indoor temperature detected by the indoor temperature sensor; In the determination of the operation condition determination unit that determines whether or not the difference between the pipe temperature detected by the pipe temperature sensor and the target evaporation temperature is smaller than the high temperature threshold, the pipe temperature and the target evaporation temperature The difference between the in the case of more than high temperature threshold, those having a compressor control unit for driving the compressor at a frequency higher than the drive frequency.

  In the air conditioner of the present invention, the target evaporation temperature ETm is set from the beginning of the cooling operation, and the operation frequency of the compressor is controlled by comparing the difference between the piping temperature ET of the indoor unit and the target evaporation temperature Etm with a set threshold value. ing. With this configuration, the air conditioner of the present invention adjusts not only the cooling operation condition for setting the room temperature to the set temperature but also the dehumidifying operation condition. As a result, comfortable air conditioning can be performed by quickly bringing the temperature and humidity close to the target values from the start of the cooling operation.

It is a block diagram of the refrigerant circuit of the air conditioner which concerns on Embodiment 1 of this invention. It is a functional block diagram of the control apparatus of the air conditioner which concerns on Embodiment 1 of this invention. It is a figure which shows the control flow of the air conditioner which concerns on Embodiment 1 of this invention. It is a functional block diagram of the control apparatus of the air conditioner which concerns on Embodiment 2 of this invention. It is a figure which shows the control flow of the air conditioner which concerns on Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a refrigerant circuit of an air conditioner according to Embodiment 1 of the present invention. The air conditioner 1 is for air conditioning an air-conditioning target space, and includes an outdoor unit 11 and an indoor unit 12, and the outdoor unit 11 and the indoor unit 12 are connected via a refrigerant pipe 13.

  The outdoor unit 11 includes a compressor 21, a flow path switch 22, an outdoor heat exchanger 23, an expansion valve 24, an outdoor blower 31, and a control device 40. The indoor unit 12 includes an indoor heat exchanger 25, an indoor fan 32, a pipe temperature sensor 33, an indoor temperature sensor 34, and an indoor fan rotation speed sensor 36. The air conditioner 1 also includes a refrigerant circuit 15 in which a compressor 21, an outdoor heat exchanger 23, an expansion valve 24, and an indoor heat exchanger 25 are connected via a refrigerant pipe 13. A refrigeration cycle is formed by circulation.

  The compressor 21 is formed using a known technique such as a scroll type or a rotary type, for example, and compresses and discharges the refrigerant. The capacity of the compressor 21 is controlled by variably adjusting the frequency of the compressor motor (CM) by, for example, an inverter. The flow path switch 22 is, for example, a four-way valve, and switches the flow path direction of the refrigerant. The flow path switch 22 forms a refrigerant circuit that connects the discharge side of the compressor 21 and the outdoor heat exchanger 23 and connects the suction side of the compressor 21 and the indoor heat exchanger 25 during the cooling operation. On the other hand, the flow path switch 22 connects the discharge side of the compressor 21 and the indoor heat exchanger 25 during the heating operation, and forms a refrigerant circuit that connects the suction side of the compressor 21 and the outdoor heat exchanger 23. .

  The outdoor heat exchanger 23 is formed of, for example, a fin tube, and functions as a condenser during cooling operation and functions as an evaporator during heating operation. The outdoor blower 31 faces the outdoor heat exchanger 23 and supplies air to the outdoor heat exchanger 23 by rotating the outdoor fan. The indoor heat exchanger 25 is formed of, for example, a fin tube, and functions as an evaporator during cooling operation, and functions as a condenser during heating operation. The indoor blower 32 faces the indoor heat exchanger 25 and supplies air to the indoor heat exchanger 25 by rotating the indoor fan. The rotational speed of the outdoor blower 31 and the indoor blower 32 is controlled by variably adjusting the rotational speed of the fan motor (FM), for example, by an inverter or the like. The expansion valve 24 is formed of, for example, an electronic expansion valve, and adjusts the flow rate of the refrigerant flowing through the refrigerant pipe 13 by adjusting the opening degree.

  The pipe temperature sensor 33 is provided in the pipe of the indoor heat exchanger 25 and detects the pipe temperature ET of the indoor heat exchanger 25. The indoor temperature sensor 34 is provided in the indoor unit 12 and detects the indoor temperature Tr in the room where the indoor heat exchanger 25 is disposed in the control device 40. The indoor fan rotation speed sensor 36 is provided in the indoor fan 32 and detects the rotation speed Rm of the indoor fan 32.

  The control device 40 controls driving of the compressor 21 and the indoor blower 32. The control device 40 acquires the pipe temperature ET from the pipe temperature sensor 33 and the room temperature Tr from the room temperature sensor 34. Further, the control device 40 acquires the rotation speed Rm of the indoor fan 32 from the indoor fan rotation speed sensor 36. In FIG. 1, the control device 40 is provided in the outdoor unit 11, but may be provided in the indoor unit 12.

  FIG. 2 is a functional block diagram of the control device for the air conditioner according to Embodiment 1 of the present invention. The functional configuration of the control device 40 in FIG. 2 is constructed by executing a program on hardware such as a microcomputer or a computer. The control device 40 includes an operation condition setting unit 51, an operation condition determination unit 53, and a compressor control unit 55.

  The operation condition setting unit 51 includes a drive frequency setting unit 61, a target evaporation temperature setting unit 63, and a setting condition storage unit 65. The drive frequency setting unit 61 sets the drive frequency fzd of the compressor 21 from the room temperature Tr detected by the room temperature sensor 34 and the set temperature Tset set by the operation unit 37 that is a remote controller, for example. For example, when the difference between the room temperature Tr and the set temperature Tset is large, the frequency is set to be high.

  The target evaporation temperature setting unit 63 calculates the dew point temperature obtained from the room temperature Tr using, for example, a correlation table between the humidity and the dew point temperature stored in the setting condition storage unit 65, and the dew point temperature is the target evaporation. Set to temperature ETm. The dew point temperature is calculated as a humidity of 60%, for example.

  The operating condition determination unit 53 determines whether or not the difference between the pipe temperature ET detected by the pipe temperature sensor 33 and the target evaporation temperature ETm is smaller than a set threshold value.

  Specifically, the operating condition determination unit 53 has a temperature difference ΔET (ΔET = ET−ETm) between the pipe temperature ET and the target evaporation temperature ETm, for example, smaller than a low temperature threshold (for example, −2 ° C.) (ΔET <−2). ) Or not. When the temperature difference ΔET is equal to or higher than the low temperature threshold (ΔET ≧ −2), it is further determined whether or not the temperature difference ΔET is smaller than, for example, a high temperature threshold (for example, 0 ° C.) (ΔET <0).

  The compressor control unit 55 adjusts the piping temperature of the indoor heat exchanger by adjusting the frequency of the compressor motor (CM) and controlling the capacity of the compressor 21 based on the determination result by the operating condition determination unit 53. Adjust the room temperature and humidity.

  Specifically, when the temperature difference ΔET is ΔET <−2, since the pipe temperature Et is lower than the target evaporation temperature Etm, water vapor in the room air is condensed in the indoor heat exchanger 25. Therefore, it is a state which can fully dehumidify. Therefore, the compressor control unit 55 adjusts the room temperature by controlling the rotation speed of the compressor 21 based on the set drive frequency fzd.

  When the temperature difference ΔET is ΔET ≧ −2 and ΔET <0, the pipe temperature Et is lower than the target evaporation temperature Etm, so that the dehumidification is possible. Become. Therefore, the compressor control unit 55 maintains the state of condensation without reducing the rotation speed of the compressor 21 and without increasing the evaporation temperature. When the set drive frequency fzd can lower the piping temperature Et by increasing the rotation speed of the compressor 21, the rotation speed of the compressor 21 is controlled based on the set drive frequency fzd to control the room temperature and humidity. Make adjustments.

  When the temperature difference ΔET is ΔET ≧ 0, the pipe temperature Et is higher or equal to the target evaporation temperature Etm, so that it cannot be dehumidified or has a low dehumidifying ability. Therefore, the compressor control unit 55 increases the frequency regardless of the set drive frequency fzd, and reduces the pipe temperature Et to a dehumidifying temperature.

  FIG. 3 is a diagram showing a control flow of the air conditioner according to Embodiment 1 of the present invention. The indoor set temperature Tset is input to the operation unit 37 (step ST1), and the cooling operation is started (step ST2). The room temperature Tr detected by the room temperature sensor 34 is input to the operating condition setting unit 51 (step ST3). The operating condition setting unit 51 calculates the output of the compressor based on the set temperature Tset and the room temperature Tr, and sets the drive frequency fzd (step ST4). The target evaporation temperature setting unit 63 calculates the dew point temperature obtained from the room temperature Tr, and sets the dew point temperature as the target evaporation temperature ETm (step ST5).

  The operating condition determination unit 53 acquires the pipe temperature ET from the pipe temperature sensor 33 (step ST6). The operating condition determination unit 53 determines whether or not the temperature difference ΔET (ΔET = ET−ETm) between the pipe temperature ET and the target evaporation temperature ETm is smaller than a low temperature threshold (for example, −2 ° C.) (ΔET <−2). (Step ST7).

  When the operating condition determination unit 53 determines that the temperature difference ΔET is smaller than −2 ° C. (ΔET <−2) (YES in step ST7), the compressor control unit 55 sets the drive frequency set in the compressor 21. fzd is output (step ST8).

  When the operating condition determining unit 53 determines that the temperature difference ΔET is −2 ° C. or more (ΔET ≧ −2) (NO in step ST7), the operating condition determining unit 53 determines the temperature difference ΔET (ΔET = ET−ETm). It is further determined whether or not is smaller than a high temperature threshold (for example, 0 ° C.) (ΔET <0) (step ST9).

  When the operating condition determination unit 53 determines that the temperature difference ΔET is smaller than 0 ° C. (ΔET <0) (YES in step ST9), the compressor control unit 55 does not decrease the frequency (step ST10). The compressor control unit 55 outputs only when the drive frequency fzd increases the frequency.

  When the operating condition determination unit 53 determines that the temperature difference ΔET is 0 ° C. or more (ΔET ≧ 0) (NO in step ST9), the compressor control unit 55 increases the frequency (step ST11).

  Thereafter, the indoor temperature sensor 34 detects the changed indoor temperature Tr based on the driving of the compressor 21 controlled in (Step ST8), (Step ST10), and (Step ST11) (Step ST3). Repeated (step ST3 to step ST11).

  As described above, the target evaporation temperature ETm is set from the beginning of the cooling operation, and the operation frequency of the compressor is controlled by comparing the difference between the piping temperature ET of the indoor unit and the target evaporation temperature Etm with the set threshold value. With this configuration, not only the cooling operation condition for setting the room temperature to the set temperature but also the dehumidification operation condition are adjusted. As a result, comfortable air conditioning can be performed by quickly bringing the temperature and humidity close to the target values from the start of the cooling operation. That is, the cooling operation and the dehumidifying operation are conventionally performed in order, but in the first embodiment, the cooling operation can always be performed in the dehumidified state.

Embodiment 2. FIG.
FIG. 4 is a functional block diagram of a control device for an air conditioner according to Embodiment 2 of the present invention. The part which has the same structure as the air conditioner of FIGS. 1-3 is attached | subjected with the same code | symbol, and the description is abbreviate | omitted. In the first embodiment, the compressor output is controlled by the temperature difference ΔET. Next, the temperature difference ΔTj (indoor temperature Tr−set temperature Tset) is smaller than the set threshold value, and the indoor fan 32 Embodiment 2 in which the rotational speed of the indoor fan 32 is controlled when the rotational speed Rm is not the minimum rotational speed will be described.

  The functional configuration of the control device 40 in FIG. 4 is constructed by executing a program on hardware such as a microcomputer or a computer. The control device 40 includes an operation condition setting unit 51, an operation condition determination unit 53, a compressor control unit 55, and an indoor fan control unit 57.

  The operating condition determination unit 53 determines whether or not the difference between the pipe temperature ET detected by the pipe temperature sensor 33 and the target evaporation temperature ETm is smaller than a set threshold value. The operating condition determination unit 53 further determines whether or not the difference between the room temperature Tr and the set temperature Tset is smaller than a set threshold value, and whether the rotation speed Rm of the indoor blower 32 is not the minimum rotation speed.

  Specifically, the operating condition determination unit 53 determines that the temperature difference ΔET (ΔET = ET−ETm) between the pipe temperature ET and the target evaporation temperature ETm is smaller than a low temperature threshold (for example, −2 ° C.) (ΔET <−2). It is determined whether or not. When the temperature difference ΔET is −2 ° C. or more (ΔET ≧ −2), it is further determined whether or not the temperature difference ΔET is smaller than a high temperature threshold (for example, 0 ° C.) (ΔET <0). When the temperature difference ΔET is smaller than 0 ° C. (ΔET <0), the temperature difference ΔTj (room temperature Tr−set temperature Tset) is further smaller than the room temperature threshold (for example, 2 ° C.) (ΔTj <2), and the room It is determined whether or not the rotational speed Rm of the blower 32 is not the minimum rotational speed (Rm ≠ Min). When the temperature difference ΔET is 0 ° C. or more (ΔET ≧ 0), the temperature difference ΔTj (room temperature Tr−set temperature Tset) is also smaller than the room temperature threshold (for example, 2 ° C.) (ΔTj <2), and the room It is determined whether or not the rotational speed Rm of the blower 32 is not the minimum rotational speed (Rm ≠ Min).

  The indoor blower control unit 57 controls the rotational speed of the indoor blower 32 by adjusting the rotational speed of the fan motor (FM) of the indoor blower 32 based on the determination result from the operating condition determination unit 53, and the indoor heat exchanger Adjust the pipe temperature.

  Specifically, when the temperature difference ΔET is not the temperature difference ΔET <−2, that is, when the pipe temperature Et is close to the target evaporation temperature Etm or higher than the target evaporation temperature Etm, the pipe temperature Et further increases. It is in a state where it cannot be dehumidified or in a state where it cannot be dehumidified. The indoor blower control unit 57 determines that when ΔTj <2 and Rm ≠ Min, that is, when the room temperature Tr is close to the set temperature Tset or lower than the set temperature Tset, and the rotational speed Rm of the indoor blower 32 is the minimum rotational speed. If not, the rotational speed of the indoor blower 32 is reduced. By reducing the rotation speed of the indoor blower 32, heat exchange of the indoor heat exchanger is suppressed, and the latent heat capacity is increased.

  FIG. 5 is a diagram showing a control flow of the air conditioner according to Embodiment 2 of the present invention. The indoor set temperature is input to the operation unit 37 (step ST21), and the cooling operation is started (step ST22). The room temperature Tr detected by the room temperature sensor 34 is input to the operating condition setting unit 51 (step ST23). The operating condition setting unit 51 calculates the output of the compressor based on the set temperature Tset and the room temperature Tr, and sets the drive frequency fzd (step ST24). The target evaporation temperature setting unit 63 calculates the dew point temperature obtained from the room temperature Tr, and sets the dew point temperature as the target evaporation temperature ETm (step ST25).

  The operating condition determination unit 53 acquires the pipe temperature ET from the pipe temperature sensor 33 (step ST26). The operating condition determination unit 53 determines whether or not the temperature difference ΔET (ΔET = ET−ETm) between the pipe temperature ET and the target evaporation temperature ETm is smaller than a low temperature threshold (for example, −2 ° C.) (ΔET <−2). (Step ST27).

  When the operating condition determination unit 53 determines that the temperature difference ΔET is smaller than −2 ° C. (ΔET <−2) (YES in step ST27), the compressor control unit 55 sets the drive frequency set in the compressor 21. fzd is output (step ST28).

  When the operating condition determining unit 53 determines that the temperature difference ΔET is −2 ° C. or more (ΔET ≧ −2) (NO in step ST27), the operating condition determining unit 53 determines that the temperature difference ΔET is a high temperature threshold (for example, 0 ° C.). It is further determined whether or not (ΔET <0) (step ST29).

  When the operating condition determining unit 53 determines that the temperature difference ΔET is smaller than 0 ° C. (ΔET <0) (YES in step ST29), the operating condition determining unit 53 determines the temperature difference ΔTj (indoor temperature Tr−set temperature Tset). ) Is smaller than a room temperature threshold (for example, 2 ° C.) (ΔTj <2), and it is further determined whether or not the rotational speed Rm of the indoor fan 32 is not the minimum rotational speed (Rm ≠ Min) (step ST30).

  When the operating condition determination unit 53 determines that the temperature difference ΔTj is smaller than 2 ° C. (ΔTj <2) and the rotation speed Rm of the indoor fan 32 is not the minimum rotation speed (Rm ≠ Min) (YES in step ST30). The indoor blower control unit 57 decreases the rotational speed Rm of the indoor blower 32 (step ST31).

  When the operating condition determination unit 53 determines that the temperature difference ΔET is smaller than 0 ° C. (ΔET <0) (YES in step ST29), the compressor control unit 55 sets the frequency regardless of the result of step ST30. It is not brought down (step ST32). The compressor control unit 55 outputs only when the drive frequency fzd is higher than the operation frequency.

  When the operating condition determining unit 53 determines that the temperature difference ΔET is 0 ° C. or more (ΔET ≧ 0) (NO in step ST29), the operating condition determining unit 53 has a temperature difference ΔTj smaller than 2 ° C. (ΔTj <2 ) And the rotational speed Rm of the indoor fan 32 is not the minimum rotational speed (Rm ≠ Min) (step ST33).

  When the operating condition determination unit 53 determines that the temperature difference ΔTj is smaller than 2 ° C. (ΔTj <2) and the rotation speed Rm of the indoor fan 32 is not the minimum rotation speed (Rm ≠ Min) (YES in step ST33). The indoor fan control unit 57 decreases the rotational speed Rm of the indoor fan 32 (step ST34).

  When the operating condition determination unit 53 determines that the temperature difference ΔET is 0 ° C. or more (ΔET ≧ 0) (NO in step ST29), the compressor control unit 55 increases the frequency regardless of the result of step ST33. (Step ST35).

  Thereafter, the room temperature Tr that has changed based on the driving of the compressor 21 and the indoor blower 32 controlled in (Step ST28), (Step ST32), and (Step ST35) is detected by the indoor temperature sensor 34 (Step ST23). An example process is repeated (steps ST23 to ST35).

  As described above, the rotation speed of the indoor blower is controlled, and the heat exchange in the indoor heat exchanger 25 is adjusted to adjust the evaporation temperature of the pipe temperature ET. As a result, comfortable air conditioning can be performed by quickly bringing the temperature and humidity close to the target values from the start of the cooling operation.

  The embodiment of the present invention is not limited to the first and second embodiments. For example, as an example of the compressor 21, a scroll type or rotary type compressor is shown as an example here, but any compression structure such as a reciprocating type may be used. The refrigerant circuit 15 may be provided with a flow path switch, an accumulator, and the like. The operation unit 37 is a remote controller, but may be provided in the indoor unit 12.

  DESCRIPTION OF SYMBOLS 1 Air conditioner, 11 Outdoor unit, 12 Indoor unit, 13 Refrigerant piping, 15 Refrigerant circuit, 21 Compressor, 22 Flow path switch, 23 Outdoor heat exchanger, 24 Expansion valve, 25 Indoor heat exchanger, 31 Outdoor fan, 32 indoor blower, 33 piping temperature sensor, 34 indoor temperature sensor, 36 indoor blower rotation speed sensor, 37 operation unit, 40 control device, 51 operating condition setting unit, 53 operating condition determination unit, 55 compressor control unit, 57 indoor blower Control part, 61 Drive frequency setting part, 63 Target evaporation temperature setting part, 65 Setting condition storage part.

An air conditioner according to the present invention includes a compressor, an outdoor heat exchanger, an expansion valve, a refrigerant circuit in which an indoor heat exchanger is connected via a refrigerant pipe, and an indoor temperature in which the indoor heat exchanger is installed. An indoor temperature sensor for detecting the temperature, a pipe temperature sensor for detecting the pipe temperature of the indoor heat exchanger, and a control device for controlling the compressor based on the detection results of the indoor temperature sensor and the pipe temperature sensor. Is configured to set the drive frequency of the compressor using the indoor temperature detected by the indoor temperature sensor and the set temperature, and to set the target evaporation temperature from the indoor temperature detected by the indoor temperature sensor; In the determination of the operation condition determination unit that determines whether or not the difference between the pipe temperature detected by the pipe temperature sensor and the target evaporation temperature is smaller than the high temperature threshold, the pipe temperature and the target evaporation temperature If the difference is greater than the high temperature threshold and, have a, a compressor control unit for driving the compressor at a higher frequency than the driving frequency, the operating condition determination unit, pipe temperature and the target detected by the piping temperature sensor The compressor control unit further determines whether or not the difference from the evaporation temperature is smaller than the low temperature threshold, and the compressor control unit determines that the difference between the pipe temperature and the target evaporation temperature is smaller than the high temperature threshold and equal to or higher than the low temperature threshold. In some cases, the operating frequency of the compressor is not lowered, and the compressor is driven at the driving frequency only when the driving frequency is higher than the operating frequency of the compressor .

Claims (5)

A refrigerant circuit in which a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected via a refrigerant pipe;
An indoor temperature sensor for detecting the indoor temperature of the room where the indoor heat exchanger is installed;
A pipe temperature sensor for detecting the pipe temperature of the indoor heat exchanger;
A control device for controlling the compressor based on detection results of the indoor temperature sensor and the pipe temperature sensor;
With
The control device includes:
An operating condition setting unit that sets a drive frequency of the compressor using an indoor temperature detected by the indoor temperature sensor and a set temperature, and sets a target evaporation temperature from the indoor temperature detected by the indoor temperature sensor; ,
An operating condition determination unit that determines whether or not a difference between the pipe temperature detected by the pipe temperature sensor and the target evaporation temperature is smaller than a high temperature threshold;
In the determination of the operating condition determination unit, when the difference between the pipe temperature and the target evaporation temperature is equal to or higher than the high temperature threshold, a compressor control unit that drives the compressor at a frequency higher than the drive frequency;
Having an air conditioner. The operating condition determination unit
It is further determined whether or not the difference between the pipe temperature detected by the pipe temperature sensor and the target evaporation temperature is smaller than a low temperature threshold,
The compressor controller is
In the determination of the operating condition determination unit, when the difference between the pipe temperature and the target evaporation temperature is smaller than the high temperature threshold and equal to or higher than the low temperature threshold, the driving frequency is compressed without lowering the operation frequency of the compressor. The air conditioner according to claim 1, wherein the compressor is driven at the driving frequency only when the operating frequency is higher than the operating frequency of the machine. The compressor controller is
The air conditioner according to claim 2, wherein the compressor is driven at the drive frequency when a difference between the pipe temperature and the target evaporation temperature is smaller than the low temperature threshold in the determination of the operation condition determination unit.   The said operation condition setting part calculates a dew point temperature from the indoor temperature which the said indoor temperature sensor detected, and has a correlation table which sets the said dew point temperature with the said target evaporation temperature. Air conditioner as described in. Further comprising an indoor fan facing the indoor heat exchanger;
The operating condition determination unit further determines whether or not a difference between the room temperature and a set temperature is smaller than a room temperature threshold, and whether or not the rotation speed of the indoor fan is a minimum rotation speed,
When the difference between the room temperature and the set temperature is smaller than the room temperature threshold and the rotation speed of the indoor blower is not the minimum rotation speed, the indoor blower control unit drives the indoor blower by lowering the rotation speed of the indoor blower The air conditioner according to any one of claims 1 to 4, further comprising:

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