Air conditioner

Abstract

To provide an air conditioner in one of the embodiments, capable of suppressing an increase in the dissipation power for a fan.SOLUTION: When stopping conditions are established, stop extension control is executed. The stop extension control is to actualize a fan rotating speed higher than a fan rotating speed right before the stop extension control is started. Thus, the fan rotating speed of the air conditioner is increased only during a time from when transiting from normal control to the stop extension control to when getting back from the stop extension control to the normal control. As a result, compared to the air conditioner described in a patent document 1, a period when the fan rotating speed is increased can be shortened, therefore suppressing an increase in the dissipation power of a second fan 5A.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an air conditioner for controlling room temperature.

Background Art

[0002] For example, in the air conditioner described in Patent Document 1, by increasing the air volume (wind speed) to raise the supply air temperature returning to the indoor heat exchanger, the operating time until thermo-off is extended as much as possible while suppressing the change in the temperature of the server room.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the invention described in Patent Document 1, in order to extend the operating time until thermo-off as much as possible, the air volume is increased, so there is a risk that the power consumption of the blower will increase.

[0005] In view of the above points, the present disclosure discloses an example of an air conditioner capable of suppressing an increase in the power consumption of the blower.

Means for Solving the Problems

[0006] An air conditioner that controls room temperature preferably includes at least one of the following components. That is, the component is a heat exchanger (5) that cools the air supplied into the room by using the heat generated by a vapor compression refrigerator having a compressor (2), and a blower (5A) that generates an air flow passing through the heat exchanger (5) and supplied into the room, the blower (5A) having a fan (5B) and an electric motor (5C) that rotates the fan, a suction side temperature sensor (7A) that detects the temperature of the air before heat exchange in the heat exchanger, a blowout side temperature sensor (7B) that detects the temperature of the air after heat exchange in the heat exchanger, a capacity control unit (6) that controls the rotation speed of the compressor (2) so that the detected temperature detected by the suction side temperature sensor (7A) (hereinafter referred to as the measured temperature) becomes a predetermined suction set temperature, and the capacity control unit (6) that stops the compressor (2) when a predetermined condition (hereinafter referred to as the stop condition) is satisfied for a predetermined time, and a fan control unit (6) that controls the rotation speed of the electric motor (5C) (hereinafter referred to as the fan rotation speed), the fan control unit (6) being capable of performing normal control or stop extension control. In the stop extension control, it is a control executed when the stop condition is satisfied, and the fan rotation speed becomes smaller than the fan rotation speed immediately before the start of the stop extension control.

[0007] Note that the stop condition refers to a state where the measured temperature is equal to or lower than a predetermined temperature (hereinafter referred to as the thermo-off threshold value) and the rotation speed of the compressor (2) is equal to or lower than a predetermined rotation speed. In normal control, the fan rotation speed is controlled so that the detected temperature of the blowout side temperature sensor (7B) becomes a predetermined blowout set temperature.

[0008] Thereby, in the air conditioner, it is possible to suppress an increase in the power consumption of the blower, and it is possible to suppress a large fluctuation in the room temperature.

[0009] Incidentally, the reference numerals in the above parentheses are an example showing the correspondence with the specific configuration and the like described in the embodiments described later, and the present disclosure is not limited to the specific configuration and the like indicated by the reference numerals in the above parentheses.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0011] The following "Embodiments of the Invention" show an example of embodiments belonging to the technical scope of the present disclosure. That is, the specific matters of the invention described in the claims are not limited to the specific configurations and structures shown in the following embodiments.

[0012] At least the members or parts described with reference signs are provided with at least one, unless otherwise stated such as "one". That is, when there is no statement such as "one", two or more of the members may be provided. The air conditioner shown in the present disclosure includes at least the components described with reference signs and the structural elements shown in the drawings.

[0013] (First Embodiment) <1. Outline of the Air Conditioner> In this embodiment, an example of the air conditioner according to the present disclosure is applied to an air conditioner that air-conditions a server room such as a data center or a communication machine room. Note that the air conditioner is a so-called "package air conditioner" composed of a vapor compression refrigerator.

[0014] The air conditioner 1 shown in Fig. 1 generates cooling or heating (cooling in this embodiment) for air conditioning in the server room. The air conditioner 1 includes a compressor 2, a condenser 3, an expansion valve 4, an evaporator 5, a control unit 6, first to fourth temperature sensors 7A to 7D, a first pressure sensor 7E, etc.

[0015] The compressor 2 compresses low-pressure gaseous refrigerant and supplies it to the condenser 3. The compressor 2 is driven by an electric motor (not shown). The electric motor is driven by an inverter-type drive circuit (not shown). The operation of the drive circuit is controlled by the control unit 6.

[0016] That is, the drive circuit supplies a drive current to the electric motor and can change the frequency of the drive current (hereinafter referred to as the drive frequency). The drive circuit supplies a drive current with a drive frequency corresponding to the command frequency from the control unit 6 to the electric motor. That is, the operation of the compressor 2 is controlled by the control unit 6 via the drive circuit.

[0017] The condenser 3 is a high-pressure side heat exchanger that cools the high-pressure refrigerant compressed by the compressor 2. In the condenser 3, the gaseous refrigerant is cooled and liquefied (condensed). The expansion valve 4 decompresses and expands the high-pressure refrigerant flowing out from the condenser 3 and supplies it to the evaporator 5.

[0018] The evaporator 5 evaporates the liquid-phase low-pressure refrigerant to generate cooling. The first blower 3A blows cooling air to the condenser 3. The second blower 5A generates an air flow that passes through the evaporator 5 and is supplied to the server room.

[0019] Specifically, the second blower 5A sucks in the air in the server room and supplies it to the evaporator 5, and supplies the air cooled by the evaporator 5 to the server room. The second blower 5A includes a fan 5B and an electric motor 5C that rotates the fan 5B.

[0020] The control unit 6 controls at least the opening degrees of the compressor 2, the second blower 5A, and the expansion valve 4. That is, the control unit 6 includes a capacity control unit that controls the rotation speed of the compressor 2, and a fan control unit that controls the rotation speed of the second blower 5A, that is, the rotation speed of the electric motor 5C (hereinafter referred to as the fan rotation speed).

[0021] Note that the control unit 6 is configured by a microcomputer having a CPU, a ROM, a RAM, etc. Then, by executing the software stored in the non-volatile storage unit such as the ROM by the CPU, the capacity control unit, the fan control unit, etc. are realized.

[0022] The detection signals of the first temperature sensor 7A to the fourth temperature sensor 7D and the first pressure sensor 7E are input to the control unit 6. The first temperature sensor 7A detects the temperature of the air before being cooled by the evaporator 5.

[0023] The second temperature sensor 7B detects the temperature of the air after being cooled by the evaporator 5. The third temperature sensor 7C detects the refrigerant temperature at the refrigerant outlet of the evaporator 5. The fourth temperature sensor 7D detects the refrigerant temperature at the refrigerant inlet of the evaporator 5. The first pressure sensor 7E detects the refrigerant pressure in the evaporator 5.

[0024] <2. Outline of Control> <Control of Expansion Valve> The control unit 6 controls the opening degree of the expansion valve 4 so that the superheat degree of the refrigerant at the refrigerant outlet of the evaporator 5 becomes a predetermined superheat degree. Note that the control unit 6 grasps the temperature difference between the detected temperature of the third temperature sensor 7C and the evaporation temperature calculated from the detected pressure of the first pressure sensor 7E as the superheat degree.

[0025] <Control of Compressor> The capacity control unit, that is, the control unit 6 can control the compressor 2 by suction priority control or servo-off control. The suction priority control is a control for adjusting the refrigerating capacity generated in the evaporator 5. The servo-off control is a control for stopping the compressor 2.

[0026] <Suction Priority Control> In the suction priority control, the control unit 6 controls the rotational speed of the compressor 2 so that the temperature detected by the first temperature sensor 7A (hereinafter referred to as the measured temperature in this embodiment) becomes a preset temperature (hereinafter referred to as the suction set temperature).

[0027] Specifically, when the measured temperature is higher than the suction set temperature, the control unit 6 increases the rotational speed of the compressor 2. When the measured temperature is lower than the suction set temperature, the control unit 6 decreases the rotational speed of the compressor 2.

[0028] <Thermo-off control> In the thermo-off control, the control unit 6 stops the compressor 2 when a predetermined condition (hereinafter referred to as the stop condition) is satisfied and the state continues for a predetermined time. The stop condition refers to a state where the measured temperature is equal to or lower than a predetermined temperature (hereinafter referred to as the thermo-off threshold value) and the rotational speed of the compressor 2 is equal to or lower than a predetermined rotational speed.

[0029] Note that the control unit 6 according to this embodiment grasps the "rotational speed of the compressor 2" using the drive frequency. Therefore, the control unit 6 stops the compressor 2 when the measured temperature drops to or below the thermo-off threshold value and the state where the drive frequency is equal to or lower than the frequency corresponding to the rotational speed (hereinafter referred to as the minimum frequency) continues for a predetermined time.

[0030] <Control of the second blower> The fan control unit, that is, the control unit 6, can control the second blower 5A by normal control or stop extension control. The normal control is executed at least when the suction priority control is being executed. Note that the capacity control unit and the fan control unit operate independently and in parallel with each other.

[0031] <Normal control> The control unit 6 controls the air volume of the second blower 5A so that the temperature detected by the second temperature sensor 7B (hereinafter referred to as the blow-out temperature) becomes a preset temperature (hereinafter referred to as the blow-out suction set temperature).

[0032] That is, like the compressor 2, the electric motor 5C is driven by an inverter-type drive circuit (not shown). The operation of the drive circuit is controlled by the control unit 6. The drive circuit supplies a drive current with a drive frequency corresponding to the command frequency (hereinafter also referred to as the command rotation speed Cr) from the control unit 6 to the electric motor 5C.

[0033] Then, when the blowing temperature is higher than the blowing and suction set temperature, the control unit 6 decreases the command rotation speed, and when the blowing temperature is lower than the blowing and suction set temperature, the control unit 6 increases the command rotation speed. The blowing and suction set temperature is a temperature obtained by adding a predetermined value to the suction set temperature.

[0034] <Stop extension control> The stop extension control is executed when the stop condition is satisfied, that is, when the measured temperature becomes equal to or lower than the thermo-off threshold value and the drive frequency becomes equal to or lower than the frequency. When the stop extension control is executed, at least at the start, the second blower 5A has a fan rotation speed smaller than the fan rotation speed immediately before the start of the stop extension control.

[0035] Specifically, in the stop extension control, the fan rotation speed is controlled so that the suction temperature, which is the measured temperature, becomes a predetermined temperature (hereinafter referred to as the extension threshold value) higher than the thermo-off threshold value. That is, the control unit 6 controls the command rotation speed Cr so that the measured temperature becomes the extension threshold value.

[0036] Note that since the stop extension control controls the command rotation speed Cr so that the measured temperature becomes the extension threshold value, that is, a predetermined temperature higher than the thermo-off threshold value, at least for a predetermined time from the start of the stop extension control, the fan rotation speed is smaller than the fan rotation speed immediately before the start of the stop extension control.

[0037] Therefore, when the amount of heat generated in the server room (hereinafter referred to as the heat load) fluctuates from the start of the stop extension control, the control unit 6 may set the fan rotation speed to be larger than the fan rotation speed immediately before the start of the stop extension control in order to maintain the measured temperature at the extension threshold value.

[0038] In other words, the stop extension control has a first stop extension control period in which the fan rotation speed is lower than the fan rotation speed immediately before the stop extension control is started, and a second stop extension control period after the first stop extension control period, that is, a period in which the fan rotation speed changes according to the measured temperature.

[0039] <Details of the control of the second blower (see Fig. 2)> The control of the second blower, that is, the control shown in Fig. 2, is executed simultaneously with the startup of the air conditioner 1 and stops simultaneously with the stop of the air conditioner 1. When this control is started, the control unit 6 executes normal control (S1).

[0040] Next, the control unit 6 determines whether or not the stop condition is satisfied (S2). If the stop condition is satisfied (S2: YES), the control unit 6 executes stop extension control (S3). If the stop condition is not satisfied (S2: NO), the control unit 6 continues normal control (S1).

[0041] When the stop extension control is executed, the control unit 6 determines whether or not the drive frequency of the compressor 2 is equal to or lower than the minimum frequency (S4). If the drive frequency is equal to or lower than the minimum frequency (S4: YES), the control unit 6 continues the stop extension control (S3). If the drive frequency becomes higher than the minimum frequency (S4: NO), the control unit 6 stops the stop extension control and executes normal control (S1).

[0042] <3. Features of the air conditioner according to the present embodiment (see Fig. 3)> In normal control, when the cooling load is small and the rotation speed of the compressor 2 becomes equal to or lower than the minimum frequency, the suction temperature, which is the measured temperature, becomes equal to or lower than the thermo-off threshold value (see A in Fig. 3). For this reason, since the stop condition is satisfied, the air conditioner 1 shifts from normal control to stop extension control (see B in Fig. 3).

[0043] When the control shifts to the stop extension control, the commanded rotational speed Cr is controlled so that the suction temperature, which is the measured temperature, becomes the extension threshold value. Therefore, when the heat load increases, the commanded rotational speed Cr, that is, the fan rotational speed, increases, and the measured temperature is maintained at a temperature higher than the thermo-off threshold value (see C in FIG. 3).

[0044] Then, when the heat load increases and the commanded rotational speed Cr, that is, the fan rotational speed, reaches the predetermined upper limit rotational speed and the suction temperature (measured temperature) rises (see D in FIG. 3), the rotational speed of the compressor 2 increases, so the control returns to the normal control (see E in FIG. 3).

[0045] As described above, in the present embodiment, it is possible to suppress an increase in the power consumption of the second blower 5A, and it is possible to avoid the compressor 2 from stopping (thermo-off), so it is possible to suppress a change in the temperature of the server room.

[0046] (Second Embodiment) The following description is the difference between the present embodiment and the first embodiment. Note that the description overlapping with the first embodiment is omitted.

[0047] (1. Outline of Control of Air Conditioning Apparatus) In the air conditioning apparatus according to the present embodiment, as the rotational speed control of the compressor 2, the blow-out priority control or the thermo-off control is executed. That is, in the present embodiment, the blow-out priority control is executed instead of the suction priority control.

[0048] (Control of Compressor) In the blow-out priority control, the rotational speed of the compressor 2 is controlled so that the temperature detected by the second temperature sensor 7B, that is, the blow-out temperature (hereinafter, in the present embodiment, referred to as the measured temperature), becomes the predetermined blow-out set temperature.

[0049] Note that the thermo-off control is the same as that of the air conditioning apparatus 1 according to the first embodiment. However, in the present embodiment, since the blow-out temperature is adopted as the measured temperature, at least the specific value of the thermo-off threshold value is different from the specific value of the thermo-off threshold value according to the first embodiment.

[0050] <Control of the Second Blower> Also in the air conditioner according to the present embodiment, normal control or stop extension control is executed as the rotation speed control of the second blower 5A. In the normal control according to the present embodiment (hereinafter abbreviated as normal control), the fan rotation speed is controlled in conjunction with the drive frequency which is the command signal value of the capacity control unit.

[0051] That is, in the normal control, the command rotation speed Cr which is the fan rotation speed is determined as a function value with the rotation speed of the compressor 2. Therefore, when the rotation speed of the compressor 2 increases, the command rotation speed Cr increases in conjunction therewith, and when the rotation speed of the compressor 2 decreases, the command rotation speed Cr decreases in conjunction therewith.

[0052] The stop extension control according to the present embodiment (hereinafter abbreviated as stop extension control) is also executed when the stop condition is satisfied, similarly to the first embodiment. And in the stop extension control, the command rotation speed Cr is controlled so that the measured temperature which is the blowing temperature becomes the extension threshold value according to the present embodiment (hereinafter abbreviated as extension threshold value).

[0053] For this reason, in the present embodiment, at least for a predetermined time from when the stop extension control is started, the fan rotation speed is larger than the fan rotation speed immediately before the stop extension control is started.

[0054] Note that since the control unit 6 maintains the measured temperature at the extension threshold value, when the heat load generated in the server room fluctuates from when the stop extension control is started, the fan rotation speed can be smaller than the fan rotation speed immediately before the stop extension control is started.

[0055] In other words, the stop extension control has a first stop extension control period in which the fan rotation speed is larger than the fan rotation speed immediately before the stop extension control is started, and a second stop extension control period after the first stop extension control period, that is, a period in which the fan rotation speed changes according to the measured temperature.

[0056] Note that the control flow of the second blower 5A according to the present embodiment is the same as that of the second blower 5A according to the first embodiment. Therefore, the description of the control flow of the second blower 5A according to the present embodiment is omitted.

[0057] <2. Features of the air conditioner according to the present embodiment (see Fig. 4)> In normal control, when the cooling load is small and the rotation speed of the compressor 2 reaches the minimum frequency, the measured temperature, i.e., the blown air set temperature, will be below the thermo-off threshold (see A in Fig. 4). Therefore, since the stop condition is satisfied, the air conditioner 1 shifts from normal control to stop extension control.

[0058] Then, when shifting to stop extension control, the command rotation speed Cr is controlled so that the measured temperature, i.e., the blown air temperature, reaches the extension threshold. As a result, the command rotation speed Cr, that is, the fan rotation speed increases, and the measured temperature is maintained at a temperature higher than the thermo-off threshold (see B in Fig. 4).

[0059] At this time, when the heat load increases, the control unit 6 maintains the measured temperature at the extension threshold by reducing the rotation speed of the second blower 5A (see C in Fig. 4). And when the rotation speed of the second blower 5A reaches the predetermined lower limit rotation speed, the blown air temperature rises as the heat load increases (see D in Fig. 4), and the rotation speed of the compressor 2 increases, so it returns to normal control (see E in Fig. 4).

[0060] (Third Embodiment) This embodiment is a modification of the air conditioner according to the second embodiment. Note that the following description is about the differences between this embodiment and the second embodiment. The descriptions overlapping with the second embodiment are omitted.

[0061] That is, in the first embodiment and the second embodiment, after shifting from normal control to stop extension control, when the heat load increases and the driving frequency of the compressor 2 becomes higher than the minimum frequency, it returns to normal control.

[0062] In contrast, in the present embodiment, after switching from normal control to stop extension control, when the current fan rotation speed (command rotation speed Cr) becomes equal to or lower than the fan rotation speed (hereinafter referred to as the compressor interlock command rotation speed) determined as a function value of the rotation speed of the compressor 2 (in the present embodiment, the drive frequency), the control returns to normal control.

[0063] Note that FIG. 5 shows the control of the second blower according to the present embodiment. The control shown in FIG. 5 is executed simultaneously with the start of the air conditioner 1 and stops simultaneously with the stop of the air conditioner 1. When this control is activated, the control unit 6 executes normal control (S11).

[0064] Next, the control unit 6 determines whether or not the stop condition is satisfied (S12). If the stop condition is satisfied (S12: YES), the control unit 6 executes stop extension control (S13). If the stop condition is not satisfied (S12: NO), the control unit 6 continues normal control (S11).

[0065] When the stop extension control is executed, the control unit 6 determines whether the current fan rotation speed (command rotation speed Cr) is greater than the compressor interlock command rotation speed (S14).

[0066] If the current command rotation speed Cr is greater than the compressor interlock command rotation speed (S14: YES), the control unit 6 continues the stop extension control (S13). If the current command rotation speed Cr is equal to or lower than the compressor interlock command rotation speed (S14: NO), the control unit 6 stops the stop extension control and executes normal control (S11).

[0067] Thus, in the present embodiment, the release of the stop extension control is determined based on the instruction value of the normal control. Therefore, it is possible to avoid a sudden decrease in the rotation speed of the second blower 5A that has increased during the stop extension control and an extremely low blow-out temperature.

[0068] (Other Embodiments) In the above-described embodiments, the air conditioner according to the present disclosure was applied to the cooling operation. However, the present disclosure is not limited thereto. That is, the present disclosure is applicable to, for example, the heating operation of the air conditioner according to the present disclosure.

[0069] When applying the present disclosure to the heating operation, the target heat exchanger is the condenser 3, and the target blower is the first blower 3A. When the air conditioner according to the first embodiment is applied to the heating operation, "the stop extension control is a fan rotation speed larger than the fan rotation speed immediately before the start of the stop extension control". When the air conditioner according to the second embodiment is applied to the heating operation, "the stop extension control is a fan rotation speed smaller than the fan rotation speed immediately before the start of the stop extension control".

[0070] In the above-described embodiments, since the fan rotation speed was controlled so that the measured temperature reached the extension threshold value from the start of the stop extension control, as a result, the first stop extension control period occurred. However, the present disclosure is not limited thereto.

[0071] That is, in the case where the first stop extension control period is the period until a predetermined time elapses from the start of the stop extension control, in the case of the blow-out priority control, the second blower 5A may be operated at a rotation speed obtained by increasing a predetermined rotation speed from the fan rotation speed immediately before the start of the stop extension control.

[0072] In the case of the suction priority control, the first stop extension control period may operate the second blower 5A at a rotation speed obtained by subtracting a predetermined rotation speed from the fan rotation speed immediately before the start of the stop extension control.

[0073] Furthermore, the present disclosure only needs to conform to the gist of the disclosure described in the above-described embodiments, and is not limited to the above-described embodiments. Therefore, a configuration in which at least two of the above-described embodiments are combined, or a configuration in which any one of the configuration elements shown in the drawings or the configuration elements described with reference numerals in the above-described embodiments is abolished may be used.

Description of Reference Numerals

[0074] 1… Air conditioner 2… Compressor 3… Condenser 3A… First blower 4… Expansion valve 5… Evaporator 5A… Second blower 6… Control unit

Claims

1. In an air conditioner that controls room temperature, a heat exchanger that cools air supplied into a room by using heat generated by a vapor compression refrigerator having a compressor; a blower that generates an air flow passing through the heat exchanger and supplied into the room, the blower having a fan and an electric motor that rotates the fan; a suction-side temperature sensor that detects the temperature of the air before heat exchange in the heat exchanger; a blow-out-side temperature sensor that detects the temperature of the air after heat exchange in the heat exchanger; a capacity control unit that controls the rotational speed of the compressor so that the detected temperature of the suction-side temperature sensor (hereinafter referred to as the measured temperature) becomes a preset suction set temperature, and that stops the compressor when a preset condition (hereinafter referred to as the stop condition) holds for a preset time exceeding a preset time; a fan control unit that controls the rotational speed of the electric motor (hereinafter referred to as the fan rotational speed ), the fan control unit being capable of performing normal control or stop extension control, wherein the stop condition is a state in which the measured temperature is equal to or lower than a preset temperature (hereinafter referred to as the thermo-off threshold value ) and the rotational speed of the compressor is equal to or lower than a preset rotational speed, in the normal control, the fan rotational speed is controlled so that the detected temperature of the blow-out-side temperature sensor becomes a preset blow-out set temperature, and further, the stop extension control is a control executed when the stop condition holds, and includes a first stop extension control period in which the fan rotational speed is set to be lower than the fan rotational speed immediately before the start of the stop extension control, and a second stop extension control period after the first stop extension control period, in which the fan rotational speed changes according to the measured temperature. An air conditioner.

2. In an air conditioner that controls room temperature, a heat exchanger that cools air supplied into a room by using heat generated by a vapor compression refrigerator having a compressor; a blower that generates an air flow passing through the heat exchanger and supplied into the room, the blower having a fan and an electric motor that rotates the fan; a blow-out-side temperature sensor that detects the temperature of the air after heat exchange in the heat exchanger; An ability control unit that controls the rotational speed of the compressor so that the detected temperature of the blowing-side temperature sensor (hereinafter referred to as the measured temperature) becomes a preset blowing set temperature, and when a preset condition (hereinafter referred to as the stop condition) is satisfied and the state continues for a preset time exceeding the time limit, the ability control unit stops the compressor. The rotational speed of the electric motor (hereinafter referred to as the fan rotational speed). A fan control unit that controls the rotational speed of the fan, and the fan control unit is capable of performing normal control or stop extension control. The stop condition means that the measured temperature is equal to or lower than a preset temperature (hereinafter referred to as the thermo-off threshold value). And the rotational speed of the compressor is in a state equal to or lower than a preset rotational speed. In the normal control, the fan rotational speed is controlled so as to be a value determined as a function value of the command signal value of the ability control unit. Furthermore, the stop extension control is a control executed when the stop condition is satisfied, and includes a first stop extension control period in which the fan rotational speed is set to be higher than the fan rotational speed immediately before the start of the stop extension control, and a second stop extension control period after the first stop extension control period, in which the fan rotational speed changes according to the measured temperature. An air conditioner with such control.

3. The air conditioner according to claim 2, wherein when the current fan rotational speed becomes equal to or lower than a value determined as a function value of the command signal value of the ability control unit during the execution of the stop extension control, the fan control unit returns the control of the blower to the normal control.

4. The air conditioner according to any one of claims 1 to 3, wherein in the stop extension control, the fan rotational speed is controlled so that the measured temperature becomes a preset temperature higher than the thermo-off threshold value.

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