JP6881419B2 - Air conditioner - Google Patents

Description

The present disclosure relates to an air conditioner.

Conventionally, as an air conditioner, as disclosed in Japanese Patent Application Laid-Open No. 2004-108618 (Patent Document 1), the first dehumidifying operation having a large sensible heat capacity and the sensible heat capacity are higher than those of the first dehumidifying operation. There is a small second dehumidifying operation and a third dehumidifying operation having a sensible heat capacity smaller than that of the second dehumidifying operation.

Japanese Unexamined Patent Publication No. 2004-108618

In the third dehumidifying operation of the conventional air conditioner, there is a problem that the amount of dehumidification is reduced.

An object of the present disclosure is to provide an air conditioner capable of increasing the amount of dehumidification during the third dehumidification operation.

The air conditioner of the present disclosure is
A refrigerant circuit in which a compressor, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger are connected in a ring shape and a refrigerant circulates.
Equipped with a control unit
The indoor heat exchanger has a control valve and
The control unit
The first dehumidification operation that makes substantially all of the indoor heat exchanger an evaporation region, and
A second dehumidifying operation in which a part of the indoor heat exchanger is set to an evaporation region and the remaining part of the indoor heat exchanger is set to a superheat zone.
In the indoor heat exchanger, the portion on the upstream side of the control valve is set as the condensation region, while in the indoor heat exchanger, the portion on the downstream side of the control valve is set as the evaporation region, and the third dehumidifying operation is performed. ,
The compressor is controlled so that the upper limit of the frequency of the compressor during the third dehumidifying operation is higher than the upper limit of the frequency of the compressor during the second dehumidifying operation.

According to the above configuration, the upper limit of the frequency of the compressor becomes higher than the upper limit of the frequency of the compressor during the second dehumidifying operation because the control unit controls the compressor. Therefore, the amount of dehumidification during the third dehumidification operation can be increased.

In one aspect of the air conditioner,
The control unit controls the compressor so that the lower limit of the frequency of the compressor during the third dehumidifying operation is higher than the lower limit of the frequency of the compressor during the second dehumidifying operation. ..

According to the above aspect, by controlling the compressor by the control unit, the lower limit of the frequency of the compressor during the third dehumidifying operation becomes higher than the lower limit of the frequency of the compressor during the second dehumidifying operation. .. Therefore, when the room is dehumidified by the third dehumidifying operation, the so-called choke phenomenon is less likely to occur in the refrigerant circuit.

In one aspect of the air conditioner,
The control unit starts the third dehumidifying operation following the second dehumidifying operation.

According to the above aspect, the power consumption can be reduced by performing the third dehumidifying operation following the second dehumidifying operation.

In one aspect of the air conditioner,
The frequency of the compressor at the start of the third dehumidifying operation is the lower limit of the frequency of the compressor at the time of the third dehumidifying operation.

According to the above aspect, the compressor is driven at the lower limit of the frequency of the compressor at the start of the third dehumidification operation and at the time of the third dehumidification operation. As a result, after the start of the third dehumidifying operation, the refrigerant is likely to circulate.

In one aspect of the air conditioner,
When switching from the second dehumidifying operation to the third dehumidifying operation, the control unit sets the opening degree of the expansion mechanism after the end of the second dehumidifying operation to be larger than that at the end of the second dehumidifying operation. After the predetermined opening degree is set, at the start of the third dehumidifying operation, the opening degree of the expansion mechanism is set to the second predetermined opening degree larger than the first predetermined opening degree.

According to the above aspect, the opening degree of the expansion mechanism becomes the first predetermined opening degree after the end of the second dehumidifying operation and before the start of the third dehumidifying operation. The first predetermined opening is larger than the opening of the expansion mechanism at the end of the second dehumidifying operation and smaller than the second predetermined opening of the expansion mechanism at the start of the third dehumidifying operation. As a result, after the start of the third dehumidifying operation, the effect of facilitating circulation of the refrigerant can be enhanced.

It is a circuit diagram of the refrigerant circuit of the air conditioner of one Embodiment of this disclosure. It is a control block diagram of the said air conditioner. It is a schematic diagram for demonstrating the cooling dehumidification operation of the said air conditioner. It is a schematic diagram for demonstrating the over-throttle dehumidification operation of the said air conditioner. It is a schematic diagram for demonstrating the reheat dehumidification operation of the said air conditioner. It is a Moriel diagram regarding the cooling dehumidification operation, the over-throttle dehumidification operation, and the reheat dehumidification operation of the air conditioner. It is a table for comparing the operation conditions of the cooling dehumidification operation, the over-throttle dehumidification operation, and the reheat dehumidification operation of the air conditioner.

Hereinafter, the air conditioner of the present disclosure will be described in detail by the illustrated embodiment.

FIG. 1 is a circuit diagram of a refrigerant circuit RC included in the air conditioner according to the embodiment of the present disclosure.

The air conditioner includes an indoor unit 1 installed indoors to be air-conditioned and an outdoor unit 2 installed outdoors.

The indoor unit 1 is, for example, a wall-mounted indoor unit that is attached to a wall surface of the room. The indoor unit 1 measures the indoor heat exchanger 11, the indoor fan 12 that sends air to the indoor heat exchanger 11, the indoor heat exchanger temperature sensor 51 that detects the temperature of the indoor heat exchanger 11, and the indoor temperature. It has an indoor temperature sensor 52 for detecting and an indoor humidity sensor 53 for detecting indoor humidity.

The indoor heat exchanger 11 is located on the upstream side of the indoor fan 12 with respect to the air flow by the indoor fan 12. The indoor heat exchanger 11 includes a main body heat exchange unit 11a, an auxiliary heat exchange unit 11b, and an electromagnetic valve 13 as an example of a control valve in order to exchange heat between the air from the indoor fan 12 and the refrigerant. Have.

The main body heat exchange portion 11a includes a front portion 11a-1 located on the indoor user side and a back portion 11a-2 located on the side opposite to the indoor user side. Further, the front portion 11a-1 is fluidly connected to the back portion 11a-2 via the refrigerant pipes L1 and L2 and the solenoid valve 13. As a result, the refrigerant flowing from the expansion valve 24 to the main body heat exchange portion 11a can flow into the back portion 11a-2 after flowing through the front portion 11a-1.

The auxiliary heat exchange portion 11b is provided on the side opposite to the back surface portion 11a-2 side of the main body heat exchange portion 11a with respect to the front portion 11a-1 of the main body heat exchange portion 11a. That is, the auxiliary heat exchange unit 11b is located closer to the indoor user than the front portion 11a-1 of the main body heat exchange unit 11a. The volume of the auxiliary heat exchange unit 11b is smaller than that of the main body heat exchange unit 11a. Further, the auxiliary heat exchange portion 11b is fluidly connected to the front portion 11a-1 of the main body heat exchange portion 11a via the refrigerant pipe L11. As a result, the refrigerant from the expansion valve 24 side is supplied to the main body heat exchange unit 11a via the auxiliary heat exchange unit 11b. As described above, it can be said that the auxiliary heat exchange unit 11b has a refrigerant path between the refrigerant pipe L3 and the refrigerant pipe L11.

As the indoor fan 12, for example, a cross flow fan is adopted. This cross-flow fan blows out air whose temperature and the like are adjusted by the indoor heat exchanger 11 toward the room.

The solenoid valve 13 is provided in the middle portion of the refrigerant path of the indoor heat exchanger 11. More specifically, it is a valve for setting a differential pressure between the front portion 11a-1 side of the main body heat exchange portion 11a and the front portion 11a-1 side of the main body heat exchange portion 11a. The solenoid valve 13 is an on / off valve that can take only two positions, a large opening and a small opening, and is turned on when necessary (for example, during reheat dehumidification operation described later) and slightly opened from the position of the large opening. It can be switched to the degree position.

The outdoor unit 2 includes a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an expansion valve 24 as an example of an expansion mechanism, an accumulator 25, and an outdoor fan that sends air to the outdoor heat exchanger 23. It has 26 and. Further, the outdoor unit 2 includes an outdoor heat exchanger temperature sensor 56 that detects the temperature of the outdoor heat exchanger 23, an outside air temperature sensor 57 that detects the outside air temperature, and the temperature (evaporation temperature) of the refrigerant decompressed by the expansion valve 24. ) Is detected by the refrigerant temperature sensor 58. The refrigerant temperature sensor 58 is an example of the first refrigerant temperature sensor.

The outdoor heat exchanger 23 is located on the downstream side of the outdoor fan 26 with respect to the air flow by the outdoor fan 26. The refrigerant flowing in the outdoor heat exchanger 23 exchanges heat with the air from the indoor fan 12.

The expansion valve 24 is, for example, an electric valve that can be adjusted to an opening degree of 3 or more different from each other, and the opening degree changes according to a signal from the control device 100 (shown in FIG. 2).

The refrigerant circuit RC of the air conditioner includes an indoor heat exchanger 11, a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an expansion valve 24, an accumulator 25, and refrigerant pipes L3 to L9. .. More specifically, the indoor heat exchanger 11, the compressor 21, the four-way switching valve 22, the outdoor heat exchanger 23, the expansion valve 24, and the accumulator 25 are fluidly connected by the refrigerant pipes L3 to L9. As a result, the annular refrigerant circuit RC is configured. In such a refrigerant circuit RC, the refrigerant circulates when the compressor 21 is driven.

The outside air temperature sensor 57 is located upstream of the outdoor heat exchanger 23 with respect to the air flow by the outdoor fan 26. That is, when the outdoor fan 26 is driven, the outdoor air before heat exchange with the outdoor heat exchanger 23 passes through the outside air temperature sensor 57.

Although not shown, the air conditioner includes a remote controller (hereinafter, referred to as "remote controller"). The user can operate the remote controller to start or stop the automatic operation, the cooling operation, the heating operation, the dehumidifying operation, and the like.

FIG. 2 is a control block diagram of the air conditioner.

The air conditioner includes a control device 100 that controls the refrigerant circuit RC. More specifically, the control device 100 includes a microprocessor, an input / output circuit, and the like. The control device 100 compresses based on signals from the indoor heat exchanger temperature sensor 51, the indoor temperature sensor 52, the indoor humidity sensor 53, the outdoor heat exchanger temperature sensor 56, the outside air temperature sensor 57, the refrigerant temperature sensor 58, and the like. It controls the machine 21, the four-way switching valve 22, the expansion valve 24, the outdoor fan 26, the indoor fan 12, the electromagnetic valve 13, and the like. The control device 100 is an example of a control unit.

Further, the control device 100 includes a cooling dehumidification operation control unit 100a that performs a cooling dehumidification operation, an overthrottle dehumidification operation control unit 100b that performs an overslot dehumidification operation, and a reheat dehumidification operation control unit 100c that performs a reheat dehumidification operation. Have. The cooling dehumidification operation control unit 100a, the over-throttle dehumidification operation control unit 100b, and the reheat dehumidification operation control unit 100c are each composed of software. The cooling dehumidification operation is an example of the first dehumidification operation. The over-throttle dehumidification operation is an example of the second dehumidification operation. The reheat dehumidification operation is an example of the third dehumidification operation.

[Cooling and dehumidifying operation]
As shown in FIG. 1, the cooling / dehumidifying operation is started by switching the four-way switching valve 22 to the solid line switching position and activating the compressor 21. During this cooling / dehumidifying operation, the high-temperature and high-pressure refrigerant discharged from the compressor 21 flows into the outdoor heat exchanger 23 via the four-way switching valve 22. Then, the refrigerant condensed by the outdoor heat exchanger 23 is decompressed by the expansion valve 24, and then the auxiliary heat exchange portion 11b of the indoor heat exchanger 11 and the main body heat exchange portion 11a of the indoor heat exchanger 11 are subjected to this. Inflow in order. The refrigerant evaporated in the main body heat exchange section 11a and the auxiliary heat exchange section 11b returns to the suction side of the compressor 21 via the four-way switching valve 22 and the accumulator 25. In this way, when the refrigerant circulates in the refrigerant circuit RC, the cooling / dehumidifying operation control unit 100a adjusts the frequency of the compressor 21 and the opening degree of the expansion valve 24, and turns off the solenoid valve 13. As shown in FIG. 3, substantially the entire indoor heat exchanger 11 is defined as an evaporation region (the region shaded in FIG. 3). As a result, the cooling / dehumidifying operation has a high sensible heat capacity, which is the ability to change the room temperature.

Here, to make substantially all of the indoor heat exchanger 11 an evaporation region is not only when the entire indoor heat exchanger 11 is made into an evaporation region, but also a part of the indoor heat exchanger 11 under predetermined conditions. It also includes the case where only the excluded part is set as the evaporation area. When only a part of this (for example, a part of 1/3 or less of the total volume of the indoor heat exchanger 11) does not become an evaporation region, for example, a part near the refrigerant outlet of the indoor heat exchanger 11 depending on the indoor environment or the like. Is sometimes overheated.

[Over-throttle dehumidification operation]
In the over-squeezing dehumidifying operation, the refrigerant flows in the same direction as in the cooling / dehumidifying operation. At this time, the over-throttle dehumidification operation control unit 100b adjusts the frequency of the compressor 21 and the opening degree of the expansion valve 24, and turns off the solenoid valve 13 so that the one on the upstream side of the indoor heat exchanger 11 The portion is set as an evaporation region, while the remaining portion of the indoor heat exchanger 11 is set as a superheat region. For example, as shown in FIG. 4, the over-throttle dehumidification operation control unit 100b sets the auxiliary heat exchange unit 11b into an evaporation region (a region with hatched diagonal lines), while the front portion 11a-1 of the main body heat exchange unit 11a. And the back surface portion 11a-2 is set to a superheated region (a region with hatched dots). As a result, the sensible heat capacity of the over-throttle dehumidification operation is lower than that of the cooling dehumidification operation. Therefore, when the heat load in the room is neither high nor low, it is possible to dehumidify the room while suppressing a decrease in room temperature. In FIG. 4, the entire auxiliary heat exchange section 11b is drawn so as to be in the evaporation region, but it is also possible to set only a part of the auxiliary heat exchange section 11b as the evaporation zone. That is, the evaporation region is a variable region whose volume can be changed.

Further, the compressor 21 and the expansion valve 24 are controlled so that the volume of the evaporation region changes according to the load during the over-throttle dehumidification operation. For example, the over-throttle dehumidification operation control unit 100b has a compressor 21 and an expansion valve so that the evaporation area is equal to or less than a predetermined volume (for example, 2/3 of the total volume of the indoor heat exchanger 11) during the over-throttle dehumidification operation. 24 is controlled.

Here, changing according to the above load means changing according to the amount of heat supplied from the room to the evaporation area, and the amount of heat is, for example, the indoor temperature (the temperature of the air sucked by the indoor unit 1) and the amount of indoor air. It is determined by (the amount of wind blown by the indoor unit 1). Further, the above load corresponds to the required dehumidifying capacity (required cooling capacity), and can be detected based on, for example, the difference between the room temperature and the set temperature. As the set temperature, a preset temperature or a temperature set by the user with the remote controller is used.

[Reheat dehumidification operation]
In the reheat dehumidification operation, the refrigerant flows in the same direction as in the cooling dehumidification operation. At this time, the reheat dehumidifying operation control unit 100c adjusts the frequency of the compressor 21 and the opening degree of the expansion valve 24, and turns on the solenoid valve 13 so that the room heat exchanger 11 is connected to the solenoid valve 13. At least a part of the upstream side is set as a condensation area, while at least a part of the room heat exchanger 11 on the downstream side of the solenoid valve 13 is set as an evaporation area. For example, as shown in FIG. 5, the reheat dehumidification operation control unit 100c sets the auxiliary heat exchange unit 11b and the front surface portion 11a-1 of the main body heat exchange unit 11a into a condensation region (a region with lattice hatching). On the other hand, the back surface portion 11a-2 of the main body heat exchange portion 11a is set as an evaporation region (a region with shaded hatching). As a result, the reheat dehumidification operation has a lower sensible heat capacity than the over-squeeze dehumidification operation. Therefore, when the heat load in the room is low, the room can be dehumidified while suppressing the decrease in room temperature.

Further, in the reheat dehumidification operation, the solenoid valve 13 is switched to a position having a small opening degree. That is, the opening degree of the solenoid valve 13 in the reheat dehumidification operation is an opening degree corresponding to an air flow rate of less than 10 L / min. The opening degree of the solenoid valve 13 in the reheat dehumidification operation is preferably an opening degree corresponding to an air flow rate of 5 L / min. Further, the opening degree of the solenoid valve 13 in the reheat dehumidification operation is preferably an opening degree corresponding to an air flow rate of 3.5 L / min. Here, "the opening degree of the solenoid valve 13 in the reheat dehumidification operation is an opening degree corresponding to an air flow rate of less than 10 L / min" means that the air flow rate flowing through the refrigerant circuit RC at the above opening degree is 10 L / min. It does not mean that it is less than min, but that the air flow rate at the opening degree obtained from the flow rate characteristics of the solenoid valve 13 is less than 10 L / min.

The cooling dehumidifying operation, the over-squeezing dehumidifying operation, or the reheat dehumidifying operation is started in response to pressing the button of the dehumidifying operation of the remote controller. More specifically, when the dehumidification operation button is pressed, one of the cooling dehumidification operation, the over-squeeze dehumidification operation, and the reheat dehumidification operation is automatically selected based on, for example, the sensible heat ratio. To start. After that, it automatically switches to another dehumidifying operation according to the change in the sensible heat ratio. The sensible heat ratio refers to the ratio of sensible heat to total heat (= sensible heat + latent heat).

FIG. 6 is a Moriel diagram during the cooling dehumidification operation, the over-throttle dehumidification operation, and the reheat dehumidification operation of the air conditioner.

The control of the over-throttle dehumidification operation control unit 100b is performed so that the evaporation temperature of the over-throttle dehumidification operation is lower than the evaporation temperature of the cooling dehumidification operation. At this time, the opening degree of the expansion valve 24 is usually smaller than the opening degree of the expansion valve 24 during the cooling / dehumidifying operation.

The reheat dehumidification operation control unit 100c is controlled so that the evaporation temperature of the reheat dehumidification operation is lower than the evaporation temperature of the over-throttle dehumidification operation. At this time, the opening degree of the expansion valve 24 is fixed to an opening degree larger than the maximum opening degree of the expansion valve 24 during the over-throttle dehumidification operation.

FIG. 7 shows a table for comparing the operating conditions of the cooling dehumidifying operation, the over-throttle dehumidifying operation, and the reheat dehumidifying operation of the air conditioner.

The reheat dehumidification operation control unit 100c reheats the compressor 21 so that the upper limit of the frequency of the compressor 21 during the reheat dehumidification operation is higher than the upper limit of the frequency of the compressor 21 during the over-throttle dehumidification operation. The compressor 21 is controlled so that the lower limit of the frequency of the compressor 21 during the dehumidifying operation is higher than the lower limit of the frequency of the compressor 21 during the over-throttle dehumidifying operation. At this time, the upper limit of the frequency of the compressor 21 during the reheat dehumidification operation is set to, for example, 30 Hz, while the upper limit of the frequency of the compressor 21 during the over-throttle dehumidification operation is set to, for example, 20 Hz. Further, the lower limit of the frequency of the compressor 21 during the reheat dehumidification operation is set to, for example, 10 Hz, while the lower limit of the frequency of the compressor 21 during the over-throttle dehumidification operation is set to, for example, 4 Hz.

Further, the opening degree of the expansion valve 24 is adjusted by a pulse signal. The number of pulses of this pulse signal is proportional to the opening degree of the expansion valve 24. That is, as the number of pulses increases, the opening degree of the expansion valve 24 increases.

In the air conditioner having the above configuration, when the reheat dehumidification operation is started after the dehumidification operation button on the remote controller is pressed, the reheat dehumidification operation control unit 100c controls the compressor 21. As a result, the upper limit of the frequency of the compressor 21 during the reheat dehumidification operation becomes higher than the upper limit of the frequency of the compressor 21 during the over-throttle dehumidification operation. Therefore, the amount of dehumidification during the reheat dehumidification operation can be increased.

Further, since the reheat dehumidification operation control unit 100c controls the compressor 21, the lower limit of the frequency of the compressor 21 during the reheat dehumidification operation is lower than the lower limit of the frequency of the compressor 21 during the over-throttle dehumidification operation. Will also be higher. As a result, it is possible to prevent the pressure of the refrigerant between the outdoor heat exchanger 23 and the indoor heat exchanger 11 from being excessively lowered during the reheat dehumidification operation. Therefore, when the room is dehumidified by the reheat dehumidification operation, the occurrence of the choke phenomenon can be suppressed.

In the above embodiment, the lower limit of the frequency of the compressor 21 during the reheat dehumidification operation is set to be higher than the lower limit of the frequency of the compressor 21 during the over-throttle dehumidification operation. The lower limit of the frequency of the compressor 21 in the above may be the same as or lower than the lower limit of the frequency of the compressor 21 during the over-throttle dehumidification operation.

In the above embodiment, when the dehumidifying operation button of the remote control is pressed, one of the cooling dehumidifying operation, the over-squeezing dehumidifying operation, and the reheat dehumidifying operation is appropriately selected and performed. Even if the button for automatic operation is pressed, one of the cooling dehumidifying operation, the over-squeezing dehumidifying operation, and the reheat dehumidifying operation may be appropriately selected and performed. Here, in the above automatic operation, one is automatically selected from the cooling operation, the dehumidifying operation, the heating operation, etc. based on the indoor temperature, the outdoor temperature, etc., and then automatically switched to the other air conditioning operation. Is. That is, for example, the over-squeezing dehumidifying operation may be automatically started in the dehumidifying operation of the automatic operation. Further, in the dehumidification operation of the automatic operation, the cooling dehumidification operation, the over-squeeze dehumidification operation, and the reheat dehumidification operation may be automatically switched to each other in response to a change in the sensible heat ratio, for example.

In the above embodiment, the indoor heat exchanger 11 has the main body heat exchange unit 11a and the auxiliary heat exchange unit 11b, but the main body heat exchange unit 11a is provided, but the auxiliary heat exchange unit 11b is not provided. You may. In this case, during the over-throttle dehumidification operation, only a part of the main body heat exchange unit 11a may be in the evaporation region.

In the above embodiment, the solenoid valve 13 is provided between the front portion 11a-1 side of the main body heat exchange portion 11a and the front portion 11a-1 side of the main body heat exchange portion 11a. An electric valve that can be adjusted each time may be provided as an example of the control valve.

In the above embodiment, the control device 100 may be composed of an indoor control unit (not shown) on the indoor unit 1 side and an outdoor control unit (not shown) on the outdoor unit 2 side, or the indoor control. It may be composed only of the unit, or may be composed only of the outdoor control unit. In other words, the control device 100 may be partially mounted on the indoor unit 1 and the remaining other portion mounted on the outdoor unit 2, or the entire control device 100 may be mounted on the indoor unit 1. It may be mounted, or all of them may be mounted on the outdoor unit 2.

In the above embodiment, the cooling dehumidifying operation control unit 100a, the over-squeezing dehumidifying operation control unit 100b, and the reheat dehumidifying operation control unit 100c are respectively configured by software, but the cooling dehumidifying operation control unit 100a and the over-squeezing dehumidifying operation are operated. At least one of the control unit 100b and the reheat dehumidification operation control unit 100c may be configured by hardware.

In the above embodiment, the reheat dehumidification operation control unit 100c may control the outdoor fan 26 so that the reheat dehumidification operation ends after the rotation speed of the outdoor fan 26 reaches the maximum rotation speed. That is, the rotation speed of the outdoor fan 26 may reach the maximum rotation speed immediately before the end of the reheat dehumidification operation. As a result, the solenoid valve 13 can be easily turned off after the reheat dehumidification operation.

In the above embodiment, the reheat dehumidification operation control unit 100c may perform the over-squeeze dehumidification operation before the reheat dehumidification operation. In other words, the reheat dehumidification operation may be started following the over-squeeze dehumidification operation. In this case, the power consumption can be reduced.

In the above embodiment, the reheat dehumidification operation control unit 100c may drive the compressor 21 at the lower limit of the frequency of the compressor 21 in the reheat dehumidification operation at the start of the reheat dehumidification operation. For example, when the control in the table of FIG. 7 is performed on the compressor 21, the frequency of the compressor 21 may be 10 Hz at the start of the reheat dehumidification operation. By performing such control on the compressor 21, even if the solenoid valve 13 is turned on and the refrigerant flow rate in the solenoid valve 13 is less than 10 L / min, the refrigerant is less likely to be clogged in the solenoid valve 13. Therefore, after the start of the third dehumidifying operation, the refrigerant is likely to circulate.

In the above embodiment, when the reheat dehumidification operation control unit 100c switches from the overslot dehumidification operation to the heat dehumidification operation, the opening degree of the expansion valve 24 is changed from the end of the overslot dehumidification operation after the end of the overthrottle dehumidification operation. At the start of the reheat dehumidification operation, the opening degree of the expansion valve 24 may be set to a second predetermined opening degree larger than the first predetermined opening degree. By performing such control on the expansion valve 24, when switching from the over-throttle dehumidification operation to the reheat dehumidification operation, the portion upstream of the expansion valve 24 of the refrigerant circuit RC and the expansion valve 24 of the refrigerant circuit RC The differential pressure with the downstream part can be reduced stepwise. Therefore, even when the reheat dehumidification operation control unit 100c controls the compressor 21 so that the frequency of the compressor 21 becomes the lower limit value at the start of the reheat dehumidification operation, the refrigerant is used after the start of the third dehumidification operation. Becomes easier to circulate.

Although the specific embodiments of the present disclosure have been described, the present disclosure is not limited to the first to third embodiments and modifications thereof, and various modifications may be made within the scope of the present disclosure. it can. For example, a combination of modified examples of the above embodiments may be used as one embodiment of the present disclosure.

1 Indoor unit 2 Outdoor unit 11 Indoor heat exchanger 11a Main body heat exchange part 11a-1 Front part 11a-2 Back part 11b Auxiliary heat exchange part 13 Electromagnetic valve 12 Indoor fan 21 Compressor 22 Four-way switching valve 23 Outdoor heat exchanger 24 Expansion valve 25 Accumulator 26 Outdoor fan 51 Indoor heat exchanger temperature sensor 52 Indoor temperature sensor 53 Indoor humidity sensor 56 Outdoor heat exchanger temperature sensor 57 Outside air temperature sensor 58,261 Refrigerant temperature sensation 100 Control device 100a Cooling and dehumidifying operation control unit 100b Over-throttle dehumidification operation control unit 100c Reheat dehumidification operation control unit RC refrigerant circuit

Claims (4)

A refrigerant circuit (RC) in which a compressor (21), an outdoor heat exchanger (23), an expansion mechanism (24) and an indoor heat exchanger (11) are connected in a ring shape and a refrigerant circulates.
Equipped with a control unit (100)
The indoor heat exchanger (11) has a control valve (13).
The control unit (100)
The first dehumidifying operation that makes substantially all of the indoor heat exchanger (11) an evaporation region, and
A second dehumidifying operation in which a part of the indoor heat exchanger (11) is set to an evaporation region and the remaining part of the indoor heat exchanger (11) is set to a superheat region.
In the indoor heat exchanger (11), the portion on the upstream side of the control valve (13) is set as the condensation region, while in the indoor heat exchanger (11), the portion on the downstream side of the control valve (13) is set. In addition to performing the third dehumidification operation, which is the evaporation area,
The compressor (21) so that the upper limit of the frequency of the compressor (21) during the third dehumidifying operation is higher than the upper limit of the frequency of the compressor (21) during the second dehumidifying operation. ) ,
In the control unit (100), the lower limit of the frequency of the compressor (21) during the third dehumidifying operation is higher than the lower limit of the frequency of the compressor (21) during the second dehumidifying operation. An air conditioner characterized by controlling the compressor (21) as described above. In the air conditioner according to claim 1,
The control unit (100) is an air conditioner characterized in that the third dehumidifying operation is started following the second dehumidifying operation. In the air conditioner according to claim 1 or 2.
An air conditioner characterized in that the frequency of the compressor (21) at the start of the third dehumidifying operation is a lower limit of the frequency of the compressor (21) at the time of the third dehumidifying operation. In the air conditioner according to claim 3,
When the control unit (100) switches from the second dehumidifying operation to the third dehumidifying operation, after the end of the second dehumidifying operation, the opening degree of the expansion mechanism (24) is changed to the end of the second dehumidifying operation. After setting the first predetermined opening larger than the time, at the start of the third dehumidifying operation, the opening of the expansion mechanism (24) is set to the second predetermined opening larger than the first predetermined opening. An air conditioner featuring.

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