JP7343801B2 - air conditioner - Google Patents

Description

Regarding air conditioners.

The heat exchanger installed in the usage unit is divided into two heat exchange parts, and one heat exchange part functions as a condenser, while the other heat exchange part functions as an evaporator, allowing reheat dehumidification. BACKGROUND ART Air conditioners that perform operations are known.

Patent Document 1 (Japanese Unexamined Patent Publication No. 2003-314854) discloses an indoor heat exchanger having a first heat exchanger and a second heat exchanger, and an indoor heat exchanger provided between the first heat exchanger and the second heat exchanger. An air conditioner (air conditioner) that is equipped with a utilization expansion valve and a control unit that controls the opening degree of the utilization expansion valve and is capable of performing reheat dehumidification operation is disclosed.

In the air conditioner disclosed in Patent Document 1, during the reheat dehumidification operation, the control unit limits the opening degree of the utilization expansion valve to a predetermined opening degree.

In the air conditioner of Patent Document 1, when the reheat dehumidification operation is performed in a state where the temperature outside the air-conditioned space (outdoors) is low and the temperature inside the air-conditioned space (indoors) is high, the outdoor heat exchanger Most of the condensed refrigerant evaporates in the first heat exchanger and becomes gas, making it difficult to pass through the expansion valve whose opening degree is restricted, which prevents the normal flow of refrigerant in the refrigerant circuit. There was a problem in that a phenomenon (hereinafter, for convenience, this phenomenon is also referred to as a choke phenomenon) occurs.

The present disclosure proposes an air conditioner that can suppress a choke phenomenon in which the flow of refrigerant in a refrigerant circuit is obstructed by an expansion valve whose opening degree is restricted during reheat dehumidification operation.

The air conditioner according to the first aspect performs air conditioning operation in a target space. The air conditioner includes a refrigerant circuit and a control section. The refrigerant circuit is formed by connecting a compressor, a heat source heat exchanger, a first utilization heat exchange section, a utilization expansion valve, and a second utilization heat exchange section in a ring shape. The control section controls the refrigerant circuit to perform a reheat dehumidification operation in which the first heat exchange section functions as a condenser and the second heat exchange section functions as an evaporator. The opening degree of the expansion valve used is controlled by the control section. In the reheat dehumidification operation, the control unit controls the opening degree of the utilization expansion valve to a predetermined first opening degree or less, and when a predetermined condition is satisfied, the opening degree of the utilization expansion valve is temporarily made lower than the first opening degree. A large predetermined second opening degree is set.

According to the air conditioner, when the predetermined condition is satisfied in the reheat dehumidification operation, the control section temporarily sets the opening degree of the expansion valve to the second opening degree, which is larger than the first opening degree. The refrigerant that has evaporated into gas in the utilization heat exchange section is encouraged to flow into the second utilization heat exchange section. Therefore, according to the air conditioner, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the expansion valve whose opening degree is restricted is suppressed.

The air conditioner according to the second aspect is the air conditioner according to the first aspect, in which the control unit sets the predetermined condition based on the first temperature difference, which is the temperature difference between the room temperature and the temperature of the second utilization heat exchange section. judge the success or failure of

Thereby, the control unit can determine that the air conditioner is in a state where a choke phenomenon is likely to occur based on the temperature difference between the room temperature and the temperature of the second utilization heat exchange section. Therefore, according to the present air conditioner 1, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the expansion valve whose opening degree is restricted is effectively suppressed.

The air conditioner according to the third aspect is the air conditioner according to the first aspect, in which the control unit determines whether the predetermined condition is satisfied based on a second temperature difference that is a temperature difference between the room temperature and the set temperature.

Thereby, the control unit can determine, based on the temperature difference between the room temperature and the set temperature, that the air conditioner is in a state where a choke phenomenon is likely to occur. Therefore, according to the present air conditioner, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the expansion valve whose opening degree is restricted is effectively suppressed.

The air conditioner according to the fourth aspect is the air conditioner according to the first aspect, in which the control unit determines whether a predetermined condition is satisfied based on the outside temperature.

Thereby, the control unit can determine, based on the outside temperature, that the air conditioner is in a state where a choke phenomenon is likely to occur. Therefore, according to the present air conditioner, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the expansion valve whose opening degree is restricted is effectively suppressed.

The air conditioner according to the fifth aspect is the air conditioner according to the first aspect, and further includes a fan that blows air to the first heat exchange section and the second heat exchange section. The control unit determines whether a predetermined condition is satisfied based on the rotation speed of the fan.

Thereby, the control unit can determine, based on the rotation speed of the fan, that the air conditioner is in a state where a choke phenomenon is likely to occur. Therefore, according to the present air conditioner, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the expansion valve whose opening degree is restricted is effectively suppressed.

The air conditioner according to the sixth aspect is the air conditioner according to the second aspect, in which the control unit temporarily changes the opening degree of the expansion valve to the second temperature difference when the first temperature difference is less than or equal to a predetermined threshold temperature difference. Make it larger than the opening.

Thereby, the control unit can increase the degree of opening of the expansion valve as the air conditioning operation by the air conditioner is at a lower load. The lower the load of air conditioning operation, the more likely the choke phenomenon occurs. According to this air conditioner, during reheat dehumidification operation, a choke phenomenon occurs in which the flow of refrigerant in the refrigerant circuit is obstructed by an expansion valve whose opening degree is narrowed. The phenomenon is effectively suppressed.

The air conditioner according to the seventh aspect is any one of the air conditioners according to the first aspect to the second aspect, in which the control unit controls the rotation of the compressor to be faster than when the predetermined condition is not satisfied, when the predetermined condition is satisfied. Increase the number.

As a result, when the predetermined condition is met, the control unit can increase the rotation speed of the compressor to increase the amount of refrigerant circulating in the refrigerant circuit compared to when the predetermined condition is not met. can. Therefore, according to the air conditioner, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the expansion valve whose opening degree is restricted is effectively suppressed.

1 is a schematic configuration diagram of an air conditioner 1 according to an embodiment of the present disclosure. 6 is a control block diagram of the control section 6. FIG. It is a flowchart of the control flow which the control part 6 performs in reheat dehumidification operation. 7 is a flowchart of a control flow executed by the control unit 6 of the air conditioner 1 according to modification A in a reheat dehumidification operation. 7 is a flowchart of a control flow executed by the control unit 6 of the air conditioner 1 according to modification B in a reheat dehumidification operation. It is a flowchart of the control flow which the control part 6 of the air conditioner 1 based on modification C performs in reheat dehumidification operation. 7 is a flowchart of a control flow executed by the control unit 6 of the air conditioner 1 according to modification example D in a reheat dehumidification operation. It is a flowchart of the control flow which the control part 6 of the air conditioner 1 based on modification E performs in reheat dehumidification operation.

(1) Overall configuration FIG. 1 is a schematic configuration diagram of an air conditioner 1 according to an embodiment of the present disclosure.

The air conditioner 1 air-conditions a target space, such as a building (not shown), using a vapor compression refrigerant cycle. The air conditioner 1 mainly includes a heat source unit 2, a utilization unit 3, a liquid refrigerant communication pipe 4, a gas refrigerant communication pipe 5, a control section 6, and a remote control 7. The liquid refrigerant communication pipe 4 and the gas refrigerant communication pipe 5 connect the heat source unit 2 and the utilization unit 3. The heat source unit 2, the utilization unit 3, the liquid refrigerant communication pipe 4, and the gas refrigerant communication pipe 5 are connected in an annular manner by refrigerant piping to form a refrigerant circuit 100. The refrigerant circuit 100 has a refrigerant sealed inside.

Although details will be described later, in the air conditioner 1, the control unit 6 controls the refrigerant circuit 100 to realize a refrigerant cycle, thereby executing air conditioning operations such as heating operation, cooling operation, and reheat dehumidification operation.

(2) Detailed configuration (2-1) Heat source unit The heat source unit 2 is installed outdoors (on the roof of the building, near the outer wall of the building, etc.). The heat source unit 2 mainly includes a compressor 21 , a four-way switching valve 23 , a heat source heat exchanger 24 , a heat source expansion valve 25 , and a heat source fan 26 .

(2-1-1) Compressor In the refrigerant circuit 100, the compressor 21 sucks low-pressure refrigerant from the suction side 21a, compresses it to high pressure, and then discharges it from the discharge side 21b. Here, as the compressor 21, a hermetic structure compressor in which a positive displacement compression element (not shown) such as a rotary type or a scroll type is rotationally driven by a motor 22 is used. Further, the rotation speed of the motor 22 is controlled by the control unit 6 via an inverter or the like. The capacity of the compressor 21 is controlled by the controller 6 changing the rotation speed of the motor 22.

(2-1-2) Four-way switching valve The four-way switching valve 23 switches the flow direction of the refrigerant in the refrigerant circuit 100. The four-way switching valve 23 has a first port P1, a second port P2, a third port P3, and a fourth port P4. The four-way switching valve 23 is controlled by the control unit 6 to be in a first state (a state indicated by a broken line in FIG. 1) in which the first port P1 and the fourth port P4 communicate with each other and the second port P2 and the third port P3 communicate with each other. ) and a second state (the state shown by the solid line in FIG. 1) in which the first port P1 and the second port P2 communicate with each other and the third port P3 and the fourth port P4 communicate with each other.

The first port P1 is connected to the discharge side 21b of the compressor 21. The second port P2 is connected to the heat source heat exchanger 24. The third port P3 is connected to the suction side 21a of the compressor 21. The fourth port P4 is connected to the gas refrigerant communication pipe 5.

(2-1-3) Heat Source Heat Exchanger The heat source heat exchanger 24 is a heat exchanger that exchanges heat between the refrigerant and outdoor air in the refrigerant circuit 100. One end of the heat source heat exchanger 24 is connected to a heat source expansion valve 25 . The other end of the heat source heat exchanger 24 is connected to the second port P2 of the four-way switching valve 23.

(2-1-4) Heat Source Expansion Valve The heat source expansion valve 25 is an expansion mechanism that reduces the pressure of the refrigerant in the refrigerant circuit 100. The heat source expansion valve 25 is provided between the liquid refrigerant communication pipe 4 and the liquid side 24a of the heat source heat exchanger 24. The heat source expansion valve 25 is an electric expansion valve whose opening degree can be controlled. The opening degree of the heat source expansion valve 25 is controlled by the control unit 6.

(2-1-5) Heat Source Fan The heat source fan 26 generates airflow and supplies outdoor air to the heat source heat exchanger 24. The heat source fan 26 supplies outdoor air to the heat source heat exchanger 24, thereby promoting heat exchange between the refrigerant in the heat source heat exchanger 24 and the outdoor air. The heat source fan 26 is rotationally driven by a heat source fan motor 26a. The air volume of the heat source fan 26 is controlled by the controller 6 changing the rotation speed of the heat source fan motor 26a.

(2-2) Utilization unit The utilization unit 3 is installed indoors, which is the target space. The usage unit 3 mainly includes a usage heat exchanger 31, a usage expansion valve 32, a usage fan 33, a first temperature sensor 34, a second temperature sensor 35, and a third temperature sensor 36. .

(2-2-1) Utilization heat exchanger The utilization heat exchanger 31 performs heat exchange between the refrigerant and indoor air in the refrigerant circuit 100. The utilization heat exchanger 31 includes a first utilization heat exchange section 311 and a second utilization heat exchange section 312.

One end of the first utilization heat exchange section 311 is connected to the liquid refrigerant communication pipe 4. The other end of the first utilization heat exchange section 311 is connected to the utilization expansion valve 32 .

One end of the second utilization heat exchange section 312 is connected to the utilization expansion valve 32 . The other end of the second utilization heat exchange section 312 is connected to the gas refrigerant communication pipe 5.

The first utilization heat exchange section 311 and the second utilization heat exchange section 312 are arranged in the flow path of the airflow generated by the utilization fan 33. The first utilization heat exchange section 311 is arranged downstream of the second utilization heat exchange section 312 in the traveling direction of the airflow generated by the utilization fan 33 .

(2-2-2) Utilization Expansion Valve The utilization expansion valve 32 is an expansion valve that reduces the pressure of the refrigerant between the first utilization heat exchange section 311 and the second utilization heat exchange section 312. The utilization expansion valve 32 is an electric expansion valve whose opening degree can be controlled. The opening degree of the utilization expansion valve 32 is controlled by the control section 6. More specifically, the opening degree of the utilization expansion valve 32 is controlled by a drive pulse output by the control section 6. The utilization expansion valve 32 is an example of an expansion valve.

(2-2-3) Utilization fan The utilization fan 33 generates an airflow and causes indoor air to pass through the utilization heat exchanger 31. When the indoor air passes through the utilization heat exchanger 31, heat exchange between the refrigerant of the utilization heat exchanger 31 and the outdoor air is promoted.

The utilization fan 33 is rotationally driven by a utilization fan motor 33a. The air volume of the usage fan 33 is controlled by the control unit 6 by changing the rotation speed of the usage fan motor 33a.

(2-2-4) Sensor The first temperature sensor 34 is provided at the air intake port of the casing (not shown) of the usage unit 3. The first temperature sensor 34 detects the temperature of the indoor air flowing into the casing of the usage unit 3 (room temperature Tr).

The second temperature sensor 35 is provided at an air intake port of a casing (not shown) of the heat source unit 2. The second temperature sensor 35 detects the temperature of outdoor air flowing into the casing of the heat source unit 2 (outside temperature To).

The third temperature sensor 36 is provided on the surface of the second utilization heat exchange section 312. The third temperature sensor 36 detects the temperature of the second heat exchange section 312 (second heat exchange section temperature Te).

(2-3) Control Unit FIG. 2 is a control block diagram of the control unit 6. The control unit 6 sends and receives control signals to and from the compressor 21, the four-way switching valve 23, the heat source expansion valve 25, the heat source fan 26, the utilization expansion valve 32, the utilization fan 33, and the remote controller 7, respectively. Possibly connected. Further, the control unit 6 is connected to each of the first temperature sensor 34, the second temperature sensor 35, and the third temperature sensor 36 so as to be able to receive detection signals.

Although details will be described later, the control unit 6 controls the operation of the compressor 21, the four-way switching valve 23, the heat source expansion valve 25, the heat source fan 26, the utilization expansion valve 32, and the utilization fan 33, respectively. This controls the refrigerant circuit 100.

The control unit 6 is typically realized by a computer including a control calculation device and a storage device (both not shown). The control calculation device is a processor such as a CPU or GPU. The control calculation device reads a control program stored in the storage device and performs operational control according to this control program. Further, the control calculation device can write calculation results to the storage device and read information stored in the storage device according to the control program.

Note that FIG. 1 is a schematic diagram, and the control section 6 is connected to an outdoor control section provided inside the heat source unit 2 and an inside of the utilization unit 3, which are connected by a communication line that can send and receive control signals to each other. and an indoor control unit provided.

(2-4) Remote control The remote control 7 receives instructions from the user to execute any of heating operation, cooling operation, and reheat dehumidification operation, instructions to stop the air conditioner 1, set temperature Ts, set humidity Hs, etc. , and transmits the received result to the control unit 6 as a control signal. Upon receiving the set temperature Ts and constant humidity Hs, the control unit 6 records them in the storage device.

(3) Air Conditioning Operation Next, the heating operation, cooling operation, and reheat dehumidification operation, which are air conditioning operations executed by the control unit 6, will be explained.

(3-1) Heating Operation When the control unit 6 receives a control signal from the remote controller 7 regarding an instruction to execute the heating operation, it starts the heating operation. During the heating operation, the control unit 6 switches the four-way switching valve 23 to the first state (see the broken line in FIG. 1). Further, the control unit 6 sets the heat source expansion valve 25 to an opening corresponding to the set temperature Ts received from the remote controller 7, sets the utilization expansion valve 32 to a fully open or close to fully open position, and operates the compressor 21. . Thereby, the heat source heat exchanger 24 functions as a refrigerant evaporator, and the utilization heat exchanger 31 functions as a refrigerant condenser.

During heating operation, the refrigerant circuit 100 functions as follows. The high-pressure refrigerant discharged from the compressor 21 is condensed by exchanging heat with indoor air supplied by the utilization fan 33 in the utilization heat exchanger 31 . As a result, indoor air is heated and discharged into the room as conditioned air. After the condensed refrigerant passes through the heat source expansion valve 25 and is depressurized, the condensed refrigerant exchanges heat with outdoor air supplied by the heat source fan 26 in the heat source heat exchanger 24 and evaporates. The refrigerant that has passed through the heat source heat exchanger 24 is sucked into the compressor 21 and compressed.

(3-2) Cooling Operation When the control unit 6 receives a control signal from the remote controller 7 regarding an instruction to execute the cooling operation, it starts the cooling operation. During the cooling operation, the control unit 6 switches the four-way switching valve 23 to the second state (see the solid line in FIG. 1). Further, the control unit 6 sets the heat source expansion valve 25 to an opening corresponding to the set temperature Ts received from the remote controller 7, sets the utilization expansion valve 32 to a fully open or close to fully open position, and operates the compressor 21. . As a result, the heat source heat exchanger 24 functions as a refrigerant condenser, and the utilization heat exchanger 31 (in other words, the first utilization heat exchange section 311 and the second utilization heat exchange section 312) evaporates the refrigerant. Functions as a vessel.

During cooling operation, the refrigerant circuit 100 functions as follows. The high-pressure refrigerant discharged from the compressor 21 is condensed by exchanging heat with outdoor air supplied by a heat source fan 26 in a heat source heat exchanger 24 . After the condensed refrigerant passes through the heat source expansion valve 25 and is depressurized, the refrigerant exchanges heat with indoor air supplied by the utilization fan 33 in the utilization heat exchanger 31 and evaporates. As a result, the indoor air is cooled and discharged indoors as conditioned air. The refrigerant that has passed through the utilization heat exchanger 31 is sucked into the compressor 21 and compressed.

(3-3) Reheat dehumidification operation The reheat dehumidification operation is an air conditioning operation in which a part of the utilization heat exchanger 31 dehumidifies and the remaining part of the utilization heat exchanger 31 heats the dehumidified air.

The control unit 6 starts the reheat dehumidification operation upon receiving a control signal from the remote controller 7 regarding an instruction to execute the reheat dehumidification operation. During the reheat dehumidification operation, the control unit 6 switches the four-way switching valve 23 to the second state (see the solid line in FIG. 1). Furthermore, the control unit 6 opens the heat source expansion valve 25 fully open or close to fully open, reduces the opening of the utilization expansion valve 32, and operates the compressor 21. Thereby, the heat source heat exchanger 24 and the first utilization heat exchange section 311 function as a refrigerant condenser, and at least a portion of the second utilization heat exchange section 312 functions as a refrigerant evaporator. Details of the opening degree control of the utilization expansion valve 32 by the control unit 6 will be described later.

During the reheat dehumidification operation, the refrigerant circuit 100 functions as follows. The high-pressure refrigerant discharged from the compressor 21 is condensed by exchanging heat with outdoor air supplied by a heat source fan 26 in a heat source heat exchanger 24 . The refrigerant that has passed through the heat source heat exchanger 24 passes through the heat source expansion valve 25 and is then condensed by exchanging heat with indoor air supplied by the utilization fan 33 in the first utilization heat exchange section 311 as well. The refrigerant condensed in the first utilization heat exchange section 311 passes through the utilization expansion valve 32 and is depressurized, and then flows into the second utilization heat exchange section 312 where it is combined with indoor air supplied by the utilization fan 33 and heat Replace and evaporate. As a result, the indoor air is dehumidified in the second utilization heat exchange section 312 and then heated in the first utilization heat exchange section 311, so that the air, which is dehumidified but whose temperature decrease is suppressed, is used as conditioned air. It is discharged indoors. The refrigerant that has passed through the utilization heat exchanger 31 is sucked into the compressor 21 and compressed.

(3-3-1) Details of opening degree control of utilization side expansion valve in reheat dehumidification operation The control unit 6 controls the opening degree of the utilization expansion valve 32 to be equal to or lower than a predetermined first opening degree in the reheat dehumidification operation. However, when the predetermined condition is satisfied, the opening degree of the utilization expansion valve 32 is temporarily set to a predetermined second opening degree that is larger than the first opening degree.

The predetermined condition is that most of the refrigerant condensed in the heat source heat exchanger 24 evaporates in the first utilization heat exchange section 311 and becomes gas, making it difficult to pass through the utilization expansion valve 32 whose opening degree is restricted. This is a condition for determining that a phenomenon in which the normal flow of refrigerant in the refrigerant circuit 100 is obstructed (choke phenomenon) is likely to occur. The predetermined condition is, for example, a condition that is satisfied during low-load operation of the air conditioner 1. In the air conditioner 1, the control unit 6 determines whether the predetermined condition is satisfied based on the first temperature difference ΔT1, which is the temperature difference between the room temperature Tr and the second utilized heat exchange section temperature Te. More specifically, when the predetermined condition is satisfied, the first temperature difference ΔT1, which is the temperature difference between the room temperature Tr and the second heat exchanger temperature Te, is equal to or less than a preset first threshold temperature difference ΔTth1. It's time to become

FIG. 3 is a flowchart of a control flow executed by the control unit 6 in the reheat dehumidification operation. When the control unit 6 receives a control signal regarding an instruction to execute the reheat dehumidification operation from the remote controller 7, it starts this control flow together with the reheat dehumidification operation.

In step S100, the control unit 6 sets the opening degree of the utilization expansion valve 32 to a preset first opening degree or less, and proceeds to step S110. The first opening degree is the opening degree of the utilization expansion valve 32 when the control unit 6 executes the reheat dehumidification operation. More specifically, the first opening degree is an opening degree that causes the first heat exchange section 311 to function as a condenser and the second heat exchange section 312 to function as an evaporator.

In step S110, the control unit 6 acquires the room temperature Tr detected by the first temperature sensor 34, and proceeds to step S120.

In step S120, the control unit 6 acquires the second utilization heat exchange section temperature Te detected by the third temperature sensor 36, and proceeds to step S130.

In step S130, the control unit 6 calculates a first temperature difference ΔT1, which is the temperature difference between the room temperature Tr and the second utilized heat exchange section temperature Te (Tr-Te→ΔT1), and proceeds to step S140.

In step S140, the control unit 6 determines whether the first temperature difference ΔT1 is less than or equal to a preset first threshold temperature difference ΔTth1 (ΔT1≦ΔTth1?), and depending on the result, step S110 or Proceed to S150. Specifically, when determining that the first temperature difference ΔT1 is equal to or less than the first threshold temperature difference ΔTth1 (Yes), the control unit 6 proceeds to step S150. If it is determined that the first temperature difference ΔT1 is not equal to or less than the first threshold temperature difference ΔTth1 (No), the control unit 6 proceeds to step S110. In other words, in step S140, the control unit 6 determines whether the predetermined condition is satisfied or not.

The first threshold temperature difference ΔTth1 is set to a temperature difference between the room temperature Tr and the second utilized heat exchange section temperature Te, at which a choke phenomenon is likely to occur in the refrigerant circuit. The first threshold temperature difference ΔTth1 is set, for example, in a range of 13° C. or more and 30° C. or less.

In step S150, the control unit 6 sets the opening degree of the utilization expansion valve 32 to the second opening degree, and proceeds to step S160. The second opening degree is a larger opening degree than the first opening degree, and is to encourage the refrigerant that has evaporated into gas in the first heat exchange section 311 to flow into the second heat exchange section 312. This is the opening degree that allows for Therefore, while the opening degree of the utilization expansion valve 32 is at the second opening degree, the second utilization heat exchange section 312 may not function as an evaporator and the reheat dehumidification operation may be temporarily stopped. However, if it is possible to encourage the refrigerant that has evaporated into gas in the first heat exchange section 311 to flow into the second heat exchange section 312, then the second opening degree will change the degree of opening of the first heat exchange section 311. The opening degree may be such that it functions as a condenser, and the second utilization heat exchange section 312 functions as an evaporator.

In step S160, the control unit 6 determines whether a predetermined time T1 has elapsed since the opening degree of the utilization expansion valve 32 is set to the second opening degree, and depending on the result, the control unit 6 proceeds to step S100 or step S160. move on. Specifically, if it is determined that the time T1 has elapsed since the opening degree of the utilization expansion valve 32 was set to the second opening degree (Yes), the control unit 6 proceeds to step S100. If it is determined that the time T1 has not elapsed since the opening degree of the utilization expansion valve 32 was set to the second opening degree (No), the control unit 6 proceeds to step S160. In other words, the control unit 6 temporarily (during time T1) sets the opening degree of the utilization expansion valve 32 to the second opening degree. At time T1, the utilization expansion valve 32 which has reached the second opening degree prompts the refrigerant to flow from the first utilization heat exchange section 311 to the second utilization heat exchange section 312. is set to a time that allows normal flow.

When the control unit 6 receives an instruction to execute an air conditioning operation other than the reheat dehumidification operation or an instruction to stop the air conditioner 1 from the remote controller 7, it ends this control flow and ends the reheat dehumidification operation.

(4) Features (4-1)
The air conditioner 1 performs air conditioning operation in a target space. The air conditioner 1 includes a refrigerant circuit 100 and a control section 6. The refrigerant circuit 100 is formed by connecting the compressor 21, the heat source heat exchanger 24, the first utilization heat exchange section 311, the utilization expansion valve 32, and the second utilization heat exchange section 312 in a ring shape. The control unit 6 controls the refrigerant circuit 100 to perform a reheat dehumidification operation in which the first heat exchanger 311 functions as a condenser and the second heat exchanger 312 functions as an evaporator. The opening degree of the utilization expansion valve 32 is controlled by the control unit 6. In the reheat dehumidification operation, the control unit 6 controls the opening degree of the utilization expansion valve 32 to be equal to or lower than a predetermined first opening degree, and when a predetermined condition is satisfied, the opening degree of the utilization expansion valve 32 is temporarily set to the first opening degree. The predetermined second opening degree is set to be larger than the second opening degree.

According to the air conditioner 1, in the reheat dehumidification operation, when the predetermined condition is satisfied, the control unit 6 temporarily sets the opening degree of the utilization expansion valve 32 to the second opening degree, which is larger than the first opening degree. , the refrigerant that has evaporated into gas in the first heat exchange section 311 is encouraged to flow into the second heat exchange section 312 . Therefore, according to the air conditioner 1, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the usage expansion valve 32 whose opening degree is restricted is suppressed.

(4-2)
The control unit 6 determines whether the predetermined condition is satisfied based on a first temperature difference ΔT1, which is the temperature difference between the room temperature Tr and the second utilization heat exchange section temperature Te.

Thereby, the control unit 6 can determine that the air conditioner 1 is in a state where a choke phenomenon is likely to occur based on the temperature difference between the room temperature Tr and the second utilization heat exchange section temperature Te. Therefore, according to the air conditioner 1, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the utilization expansion valve 32 whose opening degree is restricted is effectively suppressed.

(5) Modification (5-1) Modification A
The predetermined conditions under which the control unit 6 temporarily sets the opening degree of the utilization expansion valve 32 to the second opening degree in the reheat dehumidification operation are not limited to the above-mentioned embodiment.

In the air conditioner 1 according to modification A, the control unit 6 determines whether the predetermined condition is satisfied based on the second temperature difference ΔT2, which is the temperature difference between the room temperature Tr and the set temperature Ts. More specifically, the predetermined condition is satisfied when the second temperature difference ΔT2, which is the temperature difference between the room temperature Tr and the set temperature Ts, is less than or equal to the second threshold temperature difference ΔTth2 set in advance.

FIG. 4 is a flowchart of a control flow executed by the control unit 6 of the air conditioner 1 according to modification A in the reheat dehumidification operation. The difference between the control flow shown in FIG. 3 and the control flow shown in FIG. 4 is that in the control flow shown in FIG. 4, step S120 is replaced with step S121, and step S130 is replaced with step S131. , and step S140 is replaced with step S141. Below, we will mainly explain the differences.

In step S110, the control unit 6 acquires the room temperature Tr detected by the first temperature sensor 34, and proceeds to step S121.

In step S121, the control unit 6 acquires the set temperature Ts from the storage device, and proceeds to step S131.

In step S131, the control unit 6 calculates a second temperature difference ΔT2, which is the temperature difference between the room temperature Tr and the set temperature Ts (Tr-Ts→ΔT2), and proceeds to step S141.

In step S141, the control unit 6 determines whether the second temperature difference ΔT2 is less than or equal to a preset second threshold temperature difference ΔTth2 (ΔT2≦ΔTth2?), and depending on the result, step S110 or Proceed to S150. Specifically, if it is determined that the second temperature difference ΔT2 is equal to or less than the second threshold temperature difference ΔTth2 (Yes), the control unit 6 proceeds to step S150. If it is determined that the second temperature difference ΔT2 is not less than the second threshold temperature difference ΔTth2 (No), the control unit 6 proceeds to step S110. In other words, in step S141, the control unit 6 determines whether a predetermined condition is satisfied or not.

The second threshold temperature difference ΔTth2 is set to a temperature difference between the room temperature Tr and the set temperature Ts at which a choke phenomenon is likely to occur in the refrigerant circuit. The second threshold temperature difference ΔTth2 is set, for example, in a range of 5° C. or more and 15° C. or less.

The control unit 6 of the air conditioner 1 according to modification A can determine that the air conditioner 1 is in a state where the choke phenomenon is likely to occur based on the temperature difference between the room temperature Tr and the set temperature Ts. can. Therefore, according to the air conditioner 1 according to the modification A, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the utilization expansion valve 32 whose opening degree is restricted is effectively suppressed. .

(5-2) Modification B
In the air conditioner 1 according to modification B, the control unit 6 determines whether the predetermined condition is met based on the outside temperature To. More specifically, the predetermined condition is satisfied when the outside temperature To becomes equal to or lower than a preset threshold temperature Tth.

FIG. 5 is a flowchart of a control flow executed by the control unit 6 of the air conditioner 1 according to modification B in the reheat dehumidification operation. The difference between the control flow shown in FIG. 3 and the control flow shown in FIG. 5 is that in the control flow shown in FIG. 5, step S110 is replaced with step S112, and step S140 is replaced with step S142. , and there is no step S120 or step S130. Below, we will mainly explain the differences.

In step S100, the control unit 6 sets the opening degree of the utilization expansion valve 32 to a preset first opening degree or less, and proceeds to step S112.

In step S112, the control unit 6 acquires the outside temperature To detected by the second temperature sensor 35, and proceeds to step S142.

In step S142, the control unit 6 determines whether the outside temperature To is equal to or lower than a preset threshold temperature Tth (To≦Tth?), and proceeds to step S112 or step S150 depending on the result. Specifically, if it is determined that the outside temperature To is equal to or lower than the threshold temperature Tth (Yes), the control unit 6 proceeds to step S150. If it is determined that the outside temperature To is not equal to or lower than the threshold temperature Tth (No), the control unit 6 proceeds to step S112. In other words, in step S142, the control unit 6 determines whether a predetermined condition is satisfied or not.

The threshold temperature Tth is set to an outside temperature To at which a choke phenomenon is likely to occur in the refrigerant circuit. The threshold temperature Tth is set, for example, in a range of 10° C. or more and 18° C. or less.

The control unit 6 of the air conditioner 1 according to modification B can determine, based on the outside temperature To, that the air conditioner 1 is in a state where the choke phenomenon is likely to occur. Therefore, according to the air conditioner 1 according to modification B, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the utilization expansion valve 32 whose opening degree is restricted is effectively suppressed. .

(5-3) Modification C
In the air conditioner 1 according to modification C, the control unit 6 determines whether the predetermined condition is met based on the rotation speed Rc of the compressor 21. More specifically, the predetermined condition is satisfied when the motor 22 of the compressor 21 becomes equal to or less than a preset first threshold rotation speed Rth1.

FIG. 6 is a flowchart of a control flow executed by the control unit 6 of the air conditioner 1 according to modification C in the reheat dehumidification operation. The difference between the control flow shown in FIG. 3 and the control flow shown in FIG. 6 is that in the control flow shown in FIG. 6, step S110 is replaced with step S113, and step S140 is replaced with step S143. , and there is no step S120 or step S130. Below, we will mainly explain the differences.

In step S100, the control unit 6 sets the opening degree of the utilization expansion valve 32 to be equal to or less than a preset first opening degree, and proceeds to step S113.

In step S113, the control unit 6 obtains the rotation speed Rc of the motor 22, and proceeds to step S143.

In step S143, the control unit 6 determines whether the rotation speed Rc is less than or equal to a first threshold rotation speed Rth1 set in advance (Rc≦Rth1?), and proceeds to step S113 or step S150 depending on the result. move on. Specifically, when determining that the rotation speed Rc is equal to or lower than the first threshold rotation speed Rth1 (Yes), the control unit 6 proceeds to step S150. If it is determined that the rotation speed Rc is not equal to or lower than the first threshold rotation speed Rth1 (No), the control unit 6 proceeds to step S113. In other words, in step S143, the control unit 6 determines whether the predetermined condition is satisfied or not.

The first threshold rotation speed Rth1 is set to the rotation speed Rc of the motor 22 at which a choke phenomenon is likely to occur in the refrigerant circuit. The first threshold rotation speed Rth1 is set, for example, in a range of 2400 rpm or more and 3600 rpm or less.

According to the air conditioner 1 according to modification C, it can be determined based on the rotation speed Rc of the motor 22 that the air conditioner 1 is in a state where the choke phenomenon is likely to occur. Therefore, the air conditioner 1 according to the modification C also effectively suppresses the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the utilization expansion valve 32 whose opening degree is restricted during the reheat dehumidification operation. .

(5-4) Modification D
In the air conditioner 1 according to modification D, the control unit 6 determines whether the predetermined condition is satisfied based on the rotation speed Ra of the fan 33 used. More specifically, the predetermined condition is satisfied when the fan motor 33a of the fan 33 in use becomes equal to or less than the second threshold rotation speed Rth2 set in advance.

FIG. 7 is a flowchart of a control flow executed by the control unit 6 of the air conditioner 1 according to modification C in the reheat dehumidification operation. The difference between the control flow shown in FIG. 3 and the control flow shown in FIG. 7 is that in the control flow shown in FIG. 7, step S110 is replaced with step S113, and step S140 is replaced with step S144. , and there is no step S120 or step S130. Below, we will mainly explain the differences.

In step S100, the control unit 6 sets the opening degree of the utilization expansion valve 32 to a preset first opening degree or less, and proceeds to step S114.

In step S114, the control unit 6 obtains the rotation speed Ra of the fan motor 33a, and proceeds to step S144.

In step S144, the control unit 6 determines whether the rotation speed Ra is less than or equal to a second threshold rotation speed Rth2 set in advance (Ra≦Rth2?), and proceeds to step S114 or step S150 depending on the result. move on. Specifically, if it is determined that the rotation speed Ra is equal to or less than the threshold rotation speed Rth (Yes), the control unit 6 proceeds to step S150. If it is determined that the rotation speed Ra is not equal to or lower than the threshold rotation speed Rth (No), the control unit 6 proceeds to step S114. In other words, in step S144, the control unit 6 determines whether the predetermined condition is satisfied or not.

The second threshold rotation speed Rth2 is set to the rotation speed Ra of the fan motor 33a at which a choke phenomenon is likely to occur in the refrigerant circuit. The second threshold rotation speed Rth2 is set, for example, in a range of 900 rpm or more and 1400 rpm or less.

According to the air conditioner 1 according to modification example D, it can be determined based on the rotation speed Ra of the fan motor 33a that the air conditioner 1 is in a state where the choke phenomenon is likely to occur. Therefore, the air conditioner 1 according to Modification D also effectively suppresses the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the utilization expansion valve 32 whose opening degree is narrowed during the reheat dehumidification operation. .

(5-5) Modification E
In the air conditioner 1 according to modification E, the control unit 6 temporarily changes the opening degree of the utilization expansion valve 32 to the second opening degree when the first temperature difference ΔT1 is equal to or higher than the predetermined third threshold temperature difference ΔTth3. Make it bigger than.

FIG. 8 is a flowchart of a control flow executed by the control unit 6 of the air conditioner 1 according to modification E in the reheat dehumidification operation. The difference between the control flow shown in FIG. 3 and the control flow shown in FIG. 8 is that step S145 and step S155 are added to the control flow shown in FIG. Below, we will mainly explain the differences.

In step S140, the control unit 6 determines whether the first temperature difference ΔT1 is less than or equal to a preset first threshold temperature difference ΔTth1 (ΔT1≦ΔTth1?), and depending on the result, step S110 or Proceed to S145. Specifically, when determining that the first temperature difference ΔT1 is equal to or less than the first threshold temperature difference ΔTth1 (Yes), the control unit 6 proceeds to step S145. If it is determined that the first temperature difference ΔT1 is not equal to or less than the first threshold temperature difference ΔTth1 (No), the control unit 6 proceeds to step S110. In other words, in step S140, the control unit 6 determines whether the predetermined condition is satisfied or not.

In step S145, the control unit 6 determines whether the first temperature difference ΔT1 is equal to or less than a preset third threshold temperature difference ΔTth3 (ΔT1≦ΔTth3?), and depending on the result, step S150 or Proceed to S155. Specifically, if it is determined that the first temperature difference ΔT1 is equal to or less than the third threshold temperature difference ΔTth3 (Yes), the control unit 6 proceeds to step S155. If it is determined that the first temperature difference ΔT1 is not equal to or less than the third threshold temperature difference ΔTth3 (No), the control unit 6 proceeds to step S150.

The third threshold temperature difference ΔTth3 is set to a temperature difference smaller than the first threshold temperature difference ΔTth1. The third threshold temperature difference ΔTth3 is set, for example, in a range of −2° C. or more and 2° C. or less. The third threshold temperature difference ΔTth3 is an example of a predetermined threshold temperature difference.

In step S155, the control unit 6 sets the opening degree of the utilization expansion valve 32 to a predetermined third opening degree, which is larger than the second opening degree, and proceeds to step S160.

The control unit 6 of the air conditioner 1 according to modification E controls the opening degree of the utilization expansion valve 32 when the predetermined condition is satisfied and the first temperature difference ΔT1 is equal to or less than the third threshold temperature difference ΔTth3. , temporarily set the third opening degree to be larger than the second opening degree. Thereby, the control unit 6 of the air conditioner 1 according to Modification E can increase the opening degree of the usage expansion valve 32 as the air conditioning operation by the air conditioner 1 is a low-load operation. Since the choke phenomenon is more likely to occur as the air conditioning operation is at a lower load, in the air conditioner 1 according to modification example E, in the reheating and dehumidifying operation, the usage expansion valve 32 whose opening degree is narrowed is used to reduce the amount of air in the refrigerant circuit. The choking phenomenon in which the flow of refrigerant is obstructed is effectively suppressed.

(5-6) Modification example F
In the air conditioner 1 according to modification F, when the predetermined condition is satisfied, the control unit 6 increases the rotation speed of the compressor 21 compared to when the predetermined condition is not satisfied. Specifically, when the predetermined condition is met, the control unit 6 of the air conditioner 1 according to modification E increases the rotation speed of the motor 22 compared to when the predetermined condition is not met.

The control unit 6 of the air conditioner 1 according to modification F increases the rotation speed of the compressor 21 when the predetermined condition is satisfied, and increases the amount of refrigerant circulating in the refrigerant circuit 100 when the predetermined condition is satisfied. This can be increased compared to when it is not used. Therefore, according to the air conditioner 1 according to the modification F, in the reheat dehumidification operation, the choke phenomenon in which the flow of refrigerant in the refrigerant circuit is obstructed by the utilization expansion valve 32 whose opening degree is narrowed is effectively suppressed. .

Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as described in the claims. .

1 Air conditioner 100 Refrigerant circuit 2 Heat source unit 21 Compressor 23 Four-way switching valve 24 Heat source heat exchanger 25 Heat source expansion valve 26 Heat source fan 3 Utilization unit 31 Utilization heat exchanger 311 1st utilization heat exchange section 312 2nd utilization heat Replacement part 32 Utilization expansion valve (expansion valve)
33 Usage fan (fan)
4 Liquid refrigerant communication pipe 5 Gas refrigerant communication pipe 6 Control part 7 Remote control Te Temperature of the second utilization heat exchange part To Outside temperature Tr Room temperature Ts Set temperature Tth Threshold temperature ΔT1 First temperature difference ΔT2 Second temperature difference ΔTth1 First threshold temperature Difference ΔTth2 Second threshold temperature difference ΔTth3 Third threshold temperature difference (Threshold temperature difference)
Ra Fan rotation speed Rth1 First threshold rotation speed Rth2 Second threshold rotation speed

Japanese Patent Application Publication No. 2003-314854

Claims (2)

An air conditioner (1) that performs air conditioning operation in a target space,
A refrigerant circuit (100) in which a compressor (21), a heat source heat exchanger (24), a first heat exchange section (311), an expansion valve (32), and a second heat exchange section (312) are connected in an annular manner. and,
a control unit (6) that controls the refrigerant circuit to perform a reheat dehumidification operation in which the first heat exchange unit functions as a condenser and the second heat exchange unit functions as an evaporator; Equipped with
The expansion valve is
the opening degree is controlled by the control section,
The control unit includes:
In the reheat dehumidification operation, the opening degree of the expansion valve is controlled to a predetermined first opening degree or less, and when a predetermined condition is satisfied, the opening degree of the expansion valve is temporarily set to be lower than the first opening degree. A large predetermined second opening degree,
It is determined that the predetermined condition is satisfied when the second temperature difference (ΔT2), which is the temperature difference between the room temperature and the set temperature (Ts), is less than or equal to a predetermined first threshold temperature difference ΔTth1.
Air conditioner. The control unit includes:
When the predetermined condition is satisfied, the rotation speed of the compressor is made higher than when the predetermined condition is not satisfied.
The air conditioner according to claim 1 .