JP2023107879A - Air conditioning device - Google Patents

Abstract

To provide an air conditioning device capable of suppressing a choke phenomenon that flow of a refrigerant in a refrigerant circuit is disturbed by an expansion valve whose opening is reduced, in a reheating dehumidification operation.SOLUTION: A control portion executes a reheating dehumidification operation in which a first utilization heat exchange portion is functioned as a condenser and a second utilization heat exchange portion is functioned as an evaporator by controlling a refrigerant circuit. An opening of a utilization expansion valve is controlled by the control portion. The control portion controls the opening of the utilization expansion valve to a prescribed first opening or less in the reheating dehumidification operation, temporarily controls the opening of the utilization expansion valve to a prescribed second opening larger than the first opening when prescribed conditions are established, then continues the reheating dehumidification operation in a state that the opening of the expansion valve is the prescribed first opening or less, and determines whether or not the prescribed condition is established on the basis of a first temperature difference (ΔT1) as a temperature difference between a room temperature (Tr) and a temperature (Te) of the second utilization heat exchange portion.SELECTED DRAWING: Figure 3

Description

It relates to an air conditioner.

Reheat dehumidification by dividing the utilization heat exchanger provided in the utilization unit into two heat exchange sections, one heat exchange section functioning as a condenser, and the other heat exchange section functioning as an evaporator. Air conditioners that perform operations are known.

Patent Document 1 (Japanese Patent Application Laid-Open 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 Disclosed is an air conditioner (air conditioner) capable of executing a reheat dehumidifying operation, which includes a utilization expansion valve and a control section for controlling the opening degree of the utilization expansion valve.

In the air conditioner of Patent Literature 1, in the reheat dehumidification operation, the control unit throttles the opening of the utilization expansion valve to a predetermined opening.

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 (outdoor) is low and the temperature inside the air-conditioned space (indoor) is high, the outdoor heat exchanger Most of the condensed refrigerant evaporates in the first heat exchanger and becomes gas. As a result, it becomes difficult for the refrigerant to pass through the utilization expansion valve whose opening is throttled, and the normal flow of refrigerant in the refrigerant circuit is hindered. There is a problem that a phenomenon (hereinbelow, for the sake of convenience, this phenomenon is also called a choke phenomenon) occurs.

The present disclosure proposes an air conditioner capable of suppressing a choke phenomenon in which the flow of refrigerant in a refrigerant circuit is blocked by an expansion valve whose degree of opening is reduced during reheat dehumidification operation.

An air conditioner according to a first aspect performs an air conditioning operation in a target space. An air conditioner includes a refrigerant circuit and a controller. A refrigerant circuit is formed by annularly connecting a compressor, a heat source heat exchanger, a first use heat exchange section, a use expansion valve, and a second use heat exchange section. The control unit controls the refrigerant circuit to perform a reheat dehumidification operation in which the first heat utilization unit functions as a condenser and the second heat utilization unit functions as an evaporator. The opening degree of the utilization expansion valve is controlled by the controller. 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, temporarily increases the opening degree of the utilization expansion valve to be lower than the first opening degree. After that, the reheat dehumidifying operation is continued with the opening of the utilization expansion valve equal to or less than the predetermined first opening, and the temperature difference between the room temperature and the temperature of the second utilization heat exchange section Whether or not a predetermined condition is satisfied is determined based on a certain first temperature difference.

According to this air conditioner, when the predetermined condition is established in the reheat dehumidification operation, the controller temporarily sets the opening degree of the expansion valve to the second opening degree larger than the first opening degree. The flow of the refrigerant that has evaporated in the heat-utilizing heat-exchanging part into a gas is encouraged to flow into the second heat-utilizing heat-exchanging part. Therefore, according to the air conditioner, in the reheat dehumidification operation, the choke phenomenon in which the flow of the refrigerant in the refrigerant circuit is blocked by the expansion valve whose degree of opening is reduced is suppressed.

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

The air conditioner of the second aspect performs air conditioning operation in the target space. An air conditioner includes a refrigerant circuit and a controller. A refrigerant circuit is formed by annularly connecting a compressor, a heat source heat exchanger, a first use heat exchange section, a use expansion valve, and a second use heat exchange section. The control unit controls the refrigerant circuit to perform a reheat dehumidification operation in which the first heat utilization unit functions as a condenser and the second heat utilization unit functions as an evaporator. The opening degree of the utilization expansion valve is controlled by the controller. 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, temporarily increases the opening degree of the utilization expansion valve to be lower than the first opening degree. A predetermined large second degree of opening is set, and thereafter, the reheat dehumidification operation is continued with the degree of opening of the utilization expansion valve set to the predetermined first degree of opening or less, and whether or not the predetermined condition is satisfied is determined based on the outside air temperature.

Accordingly, the control unit can determine, based on the outside air temperature, that the air conditioner is in a state where the 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 the refrigerant in the refrigerant circuit is obstructed by the expansion valve whose opening is throttled is effectively suppressed.

The air conditioner of the third aspect performs air conditioning operation in the target space. An air conditioner includes a refrigerant circuit, a controller, and a fan. A refrigerant circuit is formed by annularly connecting a compressor, a heat source heat exchanger, a first use heat exchange section, a use expansion valve, and a second use heat exchange section. The control unit controls the refrigerant circuit to perform a reheat dehumidification operation in which the first heat utilization unit functions as a condenser and the second heat utilization unit functions as an evaporator. The degree of opening of the utilization expansion valve that blows air to the first utilization heat exchange section and the second utilization heat exchange section 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, temporarily increases the opening degree of the utilization expansion valve to be lower than the first opening degree. A large predetermined second degree of opening is set, and thereafter, the reheat dehumidification operation is continued with the opening degree of the utilization expansion valve set to be equal to or less than the predetermined first degree of opening, and whether or not the predetermined condition is met is determined based on the number of revolutions of the fan.

Accordingly, the control unit can determine, based on the number of rotations of the fan, that the air conditioner is in a state where the 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 the refrigerant in the refrigerant circuit is obstructed by the expansion valve whose opening is throttled is effectively suppressed.

An air conditioner according to a fourth aspect is the air conditioner according to the first aspect, wherein the controller temporarily reduces the opening degree of the expansion valve to a second Make it larger than the opening.

As a result, the controller can increase the degree of opening of the expansion valve as the air conditioning operation of the air conditioner is performed at a lower load. The choke phenomenon is more likely to occur as the air conditioning operation is performed at a lower load. Therefore, according to this air conditioner, in the reheat dehumidification operation, the expansion valve whose opening is throttled prevents the flow of the refrigerant in the refrigerant circuit. phenomenon is effectively suppressed.

An air conditioner according to a fifth aspect is the air conditioner according to any one of the first aspect to the fourth aspect, wherein when the predetermined condition is satisfied, the controller controls the rotation of the compressor more than when the predetermined condition is not satisfied. increase the number.

As a result, when the predetermined condition is satisfied, 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 satisfied. can. Therefore, according to the air conditioner, in the reheat dehumidification operation, the choke phenomenon in which the flow of the refrigerant in the refrigerant circuit is obstructed by the expansion valve whose opening is throttled is effectively suppressed.

1 is a schematic configuration diagram of an air conditioner 1 according to an embodiment of the present disclosure; FIG. 3 is a control block diagram of a control unit 6; FIG. 6 is a flowchart of a control flow executed by the control unit 6 during reheat dehumidification operation. 9 is a flow chart of a control flow executed by the control unit 6 of the air conditioner 1 according to Modification A in the reheat dehumidification operation. 10 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. 10 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. 10 is a flowchart of a control flow executed by the control unit 6 of the air conditioner 1 according to Modification D in the reheat dehumidification operation. 10 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.

(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 room (not shown) such as a building, which is a target space, by 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 controller 6 and a remote controller 7 . A liquid refrigerant communication pipe 4 and a 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 annularly connected by refrigerant pipes to form a refrigerant circuit 100 . Refrigerant circuit 100 has a refrigerant sealed therein.

Although the 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 performing 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 a building, near the exterior wall of the building, etc.). The heat source unit 2 mainly has 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 closed-type 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 motor 22 has its rotation speed controlled by the controller 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 direction of refrigerant flow 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 the first state (the state indicated by the dashed 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 (shown by solid lines 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 P<b>4 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 the 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 24 a of the heat source heat exchanger 24 . The heat source expansion valve 25 is an electric expansion valve whose degree of opening can be controlled. The degree of opening of the heat source expansion valve 25 is controlled by the controller 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 the 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) Usage Unit The usage unit 3 is installed in the room, which is the target space. The utilization unit 3 mainly includes a utilization heat exchanger 31, a utilization expansion valve 32, a utilization 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 exchanges heat between the refrigerant and the indoor air in the refrigerant circuit 100 . The utilization heat exchanger 31 has 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 heat 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 heat-use heat exchange part 311 and the second heat-use heat exchange part 312 are arranged in the flow path of the airflow generated by the use fan 33 . The first heat utilization unit 311 is arranged downstream of the second heat utilization unit 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 decompresses 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 controller 6 . More specifically, the degree of opening of the utilization expansion valve 32 is controlled by the drive pulse output by the controller 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 passes the indoor air through the utilization heat exchanger 31 . Passing the indoor air through the heat utilization exchanger 31 promotes heat exchange between the refrigerant in the heat utilization exchanger 31 and the outdoor air.

The utilization fan 33 is rotationally driven by a utilization fan motor 33a. The air volume of the utilization fan 33 is controlled by the controller 6 by changing the rotational speed of the utilization 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 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 air temperature To).

The third temperature sensor 36 is provided on the surface of the second heat 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. As shown in FIG. The control unit 6 transmits and receives control signals to 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 control 7, respectively. connected as possible. 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. to control 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 computing unit is a processor, such as a CPU or GPU. The control arithmetic unit reads out the control program stored in the storage device and performs operation control according to this control program. Furthermore, the control arithmetic device can write the arithmetic result to the storage device and read the information stored in the storage device according to the control program.

Note that FIG. 1 is a schematic diagram, and the control unit 6 includes an outdoor control unit provided inside the heat source unit 2 and an internal control unit inside the usage unit 3, which are connected by a communication line capable of transmitting and receiving control signals. and a provided indoor control unit.

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

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

(3-1) Heating operation When the control unit 6 receives a control signal from the remote controller 7 instructing the execution of 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 broken line in FIG. 1). Furthermore, 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 nearly fully open, and operates the compressor 21. . As a result, 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 exchanges heat with the indoor air supplied by the utilization fan 33 in the utilization heat exchanger 31 and is condensed. As a result, the indoor air is heated and discharged indoors as conditioned air. After the condensed refrigerant passes through the heat source expansion valve 25 and is decompressed, it exchanges heat with the 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 control 7 instructing the execution of the cooling operation, it starts the cooling operation. During the cooling operation, the controller 6 switches the four-way switching valve 23 to the second state (see the solid line in FIG. 1). Furthermore, 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 nearly fully open, 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. function as a vessel.

During cooling operation, the refrigerant circuit 100 functions as follows. The high pressure refrigerant discharged from the compressor 21 exchanges heat with the outdoor air supplied by the heat source fan 26 in the heat source heat exchanger 24 and is condensed. After the condensed refrigerant passes through the heat source expansion valve 25 and is decompressed, it exchanges heat with the 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 heat utilization 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 part of the heat utilization heat exchanger 31 dehumidifies and the remaining part of the heat utilization heat exchanger 31 heats the dehumidified air.

The control unit 6 starts the reheat dehumidifying operation when receiving a control signal from the remote controller 7 for instructing the execution of the reheat dehumidifying 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). Further, the control unit 6 fully opens or nearly fully opens the heat source expansion valve 25 , restricts the opening of the utilization expansion valve 32 , and operates the compressor 21 . As a result, the heat source heat exchanger 24 and the first heat utilization unit 311 function as refrigerant condensers, and at least part of the second utilization heat exchange unit 312 functions as a refrigerant evaporator. The 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 exchanges heat with the outdoor air supplied by the heat source fan 26 in the heat source heat exchanger 24 and is condensed. After passing through the heat source heat exchanger 24 , the refrigerant is condensed by exchanging heat with the indoor air supplied by the utilization fan 33 also in the first utilization heat exchange section 311 after passing through the heat source expansion valve 25 . The refrigerant condensed in the first heat utilization section 311 passes through the utilization expansion valve 32 and is decompressed, and then flows into the second heat utilization heat exchange section 312, where the indoor air and heat supplied by the utilization fan 33 are supplied. Replace and evaporate. As a result, the air in the room is dehumidified in the second heat exchange unit 312 and then heated in the first heat exchange unit 311, so that the dehumidified air whose temperature drop is suppressed becomes conditioned air. discharged indoors. The refrigerant that has passed through the heat utilization exchanger 31 is sucked into the compressor 21 and compressed.

(3-3-1) Details of control of opening degree of utilization side expansion valve in reheat dehumidification operation In reheat dehumidification operation, the control unit 6 controls the opening degree of the utilization expansion valve 32 to a predetermined first opening degree or less. Then, when a predetermined condition is established, 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 heat utilization heat exchange section 311 and becomes gas, and as a result, it is difficult to pass through the utilization expansion valve 32 whose opening is throttled. This is a condition for determining that a phenomenon (choke phenomenon) in which the normal flow of the refrigerant is disturbed in the refrigerant circuit 100 is likely to occur. The predetermined condition is, for example, a condition that is met during low-load operation of the air conditioner 1 . In the air conditioner 1, the control unit 6 determines whether or not the predetermined condition is satisfied based on the first temperature difference ΔT1, which is the temperature difference between the room temperature Tr and the temperature Te of the second heat-utilizing heat exchange unit. More specifically, when the predetermined condition is established, the first temperature difference ΔT1, which is the temperature difference between the room temperature Tr and the temperature Te of the second heat exchanger, is equal to or less than a preset first threshold temperature difference ΔTth1. It is time to become

FIG. 3 is a flow chart of a control flow executed by the control unit 6 during the reheat dehumidification operation. When the control unit 6 receives a control signal for executing the reheat dehumidification operation from the remote control 7, the control unit 6 starts the reheat dehumidification operation and this control flow.

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

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

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

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

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

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

In step S150, the controller 6 sets the opening degree of the utilization expansion valve 32 to the second opening degree, and proceeds to step S160. The second degree of opening is larger than the first degree of opening, and promotes the flow of the refrigerant that has evaporated in the first heat utilization section 311 into gas into the second heat utilization section 312. is the degree of opening that allows Therefore, while the opening degree of the utilization expansion valve 32 is the second opening degree, the second utilization heat exchange section 312 may temporarily stop functioning as an evaporator and the reheat dehumidifying operation may be stopped. However, if it is possible to promote the flow of the refrigerant that has evaporated in the first heat utilization unit 311 into gas into the second heat utilization heat exchange unit 312, the second opening degree is set to allow the first heat utilization heat exchange unit 311 to flow. The degree of opening may be such that it functions as a condenser and the second heat utilization heat exchange section 312 functions as an evaporator.

In step S160, the control unit 6 determines whether or not a preset predetermined time T1 has elapsed since the opening degree of the utilization expansion valve 32 was set to the second opening degree, and depending on the result, the process proceeds to step S100 or step S160. move on. Specifically, when it is determined that 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 section 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 having the second degree of opening promotes the flow of the refrigerant from the first utilization heat exchange section 311 to the second utilization heat exchange section 312, and as a result, the inside of the refrigerant circuit 100 becomes refrigerant. is set to the time when it is possible to flow normally.

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

(4) Features (4-1)
The air conditioner 1 performs air conditioning operation in the target space. The air conditioner 1 includes a refrigerant circuit 100 and a controller 6 . The refrigerant circuit 100 is formed by annularly 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 . The control unit 6 controls the refrigerant circuit 100 to perform a reheat dehumidifying operation in which the first heat utilization unit 311 functions as a condenser and the second heat utilization unit 312 functions as an evaporator. The opening degree of the utilization expansion valve 32 is controlled by the controller 6 . In the reheat dehumidification operation, the control unit 6 controls the opening degree of the utilization expansion valve 32 to a predetermined first opening degree or less, and when a predetermined condition is satisfied, temporarily increases the opening degree of the utilization expansion valve 32 to the first opening degree. is set to a predetermined second degree of opening larger than the degree of opening.

According to the air conditioner 1, when the predetermined condition is established in the reheat dehumidification operation, the controller 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 vaporized in the first heat utilization section 311 and turned into a gas is promoted to flow into the second heat utilization heat exchange section 312 . Therefore, according to the air conditioner 1, in the reheat dehumidifying operation, the choking phenomenon in which the flow of the refrigerant in the refrigerant circuit is blocked by the utilization expansion valve 32 whose opening is throttled is suppressed.

(4-2)
The control unit 6 determines whether or not the predetermined condition is met based on the first temperature difference ΔT1, which is the temperature difference between the room temperature Tr and the temperature Te of the second heat-utilizing heat exchange section.

Thereby, the control unit 6 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 second heat utilization heat exchange unit temperature Te. Therefore, according to the air conditioner 1, in the reheat dehumidification operation, the choking phenomenon in which the flow of the refrigerant in the refrigerant circuit is blocked by the utilization expansion valve 32 whose opening is throttled is effectively suppressed.

(5) Modification (5-1) Modification A
The predetermined condition 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 is not limited to the above-described mode.

In the air conditioner 1 according to Modification A, the controller 6 determines whether or not the predetermined condition is met based on the second temperature difference ΔT2, which is the temperature difference between the room temperature Tr and the set temperature Ts. More specifically, when the predetermined condition is satisfied, the second temperature difference ΔT2, which is the temperature difference between the room temperature Tr and the set temperature Ts, is equal to or less than a 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. The following description focuses on 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 controller 6 acquires the set temperature Ts from the storage device, and proceeds to step S131.

In step S131, the controller 6 obtains 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 or not the second temperature difference ΔT2 is equal to or less than a preset second threshold temperature difference ΔTth2 (ΔT2≦ΔTth2?), and depending on the result, step S110 or step Proceed to S150. Specifically, when it is determined that the second temperature difference ΔT2 is equal to or less than the second threshold temperature difference ΔTth2 (Yes), the controller 6 proceeds to step S150. When determining that the second temperature difference ΔT2 is not equal to or less than the second threshold temperature difference ΔTth2 (No), the controller 6 proceeds to step S110. In other words, in step S141, the control section 6 determines whether or not the predetermined condition is met.

The second threshold temperature difference ΔTth2 is set to a temperature difference between the room temperature Tr and the set temperature Ts at which the choke phenomenon is likely to occur in the refrigerant circuit. The second threshold temperature difference ΔTth2 is set within a range of, for example, 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 the refrigerant in the refrigerant circuit is blocked by the utilization expansion valve 32 whose opening is throttled is effectively suppressed. .

(5-2) Modification B
In the air conditioner 1 according to Modification B, the controller 6 determines whether or not the predetermined condition is met based on the outside air temperature To. More specifically, when the predetermined condition is established, the outside air 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. The only difference is that there are no steps S120 and S130. The following description focuses on the differences.

In step S100, the controller 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 controller 6 acquires the outside air temperature To detected by the second temperature sensor 35, and proceeds to step S142.

In step S142, the control unit 6 determines whether or not the outside air 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, when determining that the outside air temperature To is equal to or lower than the threshold temperature Tth (Yes), the control unit 6 proceeds to step S150. When determining that the outside air temperature To is not equal to or lower than the threshold temperature Tth (No), the controller 6 proceeds to step S112. In other words, in step S142, the control section 6 determines whether or not the predetermined condition is met.

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

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

(5-3) Modification C
In the air conditioner 1 according to Modification C, the controller 6 determines whether the predetermined condition is satisfied based on the rotation speed Rc of the compressor 21 . More specifically, when the predetermined condition is satisfied, it is 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. The only difference is that there are no steps S120 and S130. The following description focuses on the differences.

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

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

In step S143, the control unit 6 determines whether or not the rotation speed Rc is equal to or lower than a preset first threshold rotation speed Rth1 (Rc≦Rth1?), and depending on the result, the process proceeds to step S113 or step S150. 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. When determining 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 section 6 determines whether or not the predetermined condition is met.

The first threshold rotation speed Rth1 is set to the rotation speed Rc of the motor 22 at which the choke phenomenon is likely to occur in the refrigerant circuit. The first threshold rotation speed Rth1 is set, for example, within 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 rotational speed Rc of the motor 22 that the air conditioner 1 is in a state where the choke phenomenon is likely to occur. Therefore, in the reheat dehumidification operation, the air conditioner 1 according to the modification C also effectively suppresses the choke phenomenon in which the flow of the refrigerant in the refrigerant circuit is obstructed by the utilization expansion valve 32 whose opening is throttled. .

(5-4) Modification D
In the air conditioner 1 according to Modification D, the controller 6 determines whether the predetermined condition is satisfied based on the rotation speed Ra of the utilization fan 33 . More specifically, when the predetermined condition is satisfied, it is when the fan motor 33a of the utilization fan 33 becomes equal to or less than a preset second threshold rotation speed Rth2.

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. The only difference is that there are no steps S120 and S130. The following description focuses on the differences.

In step S100, the controller 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 controller 6 acquires the rotation speed Ra of the fan motor 33a, and proceeds to step S144.

In step S144, the control unit 6 determines whether or not the rotation speed Ra is equal to or lower than a preset second threshold rotation speed Rth2 (Ra≤Rth2?), and depending on the result, the process proceeds to step S114 or step S150. move on. Specifically, when determining that the rotational speed Ra is equal to or lower than the threshold rotational speed Rth (Yes), the control unit 6 proceeds to step S150. When determining that the rotational speed Ra is not equal to or lower than the threshold rotational speed Rth (No), the control unit 6 proceeds to step S114. In other words, in step S144, the control section 6 determines whether or not the predetermined condition is met.

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

According to the air conditioner 1 according to Modification D, it is possible to determine whether the air conditioner 1 is in a state where the choke phenomenon is likely to occur, based on the rotational speed Ra of the fan motor 33a. Therefore, also in the air conditioner 1 according to the modification D, the choke phenomenon in which the flow of the refrigerant in the refrigerant circuit is obstructed by the utilization expansion valve 32 whose opening is throttled is effectively suppressed in the reheat dehumidification operation. .

(5-5) Modification E
In the air conditioner 1 according to Modification E, when the first temperature difference ΔT1 is equal to or greater than the predetermined third threshold temperature difference ΔTth3, the controller 6 temporarily sets the opening degree of the utilization expansion valve 32 to the second opening degree. make it larger 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 steps S145 and S155 are added to the control flow shown in FIG. The following description focuses on the differences.

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

In step S145, the control unit 6 determines whether or not the first temperature difference ΔT1 is equal to or less than a preset third threshold temperature difference ΔTth3 (ΔT1≦ΔTth3?). Proceed to S155. Specifically, when determining that the first temperature difference ΔT1 is equal to or less than the third threshold temperature difference ΔTth3 (Yes), the controller 6 proceeds to step S155. When determining that the first temperature difference ΔT1 is not equal to or less than the third threshold temperature difference ΔTth3 (No), the controller 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, within 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 controller 6 sets the degree of opening of the utilization expansion valve 32 to a predetermined third degree of opening larger than the second degree of opening, and proceeds to step S160.

The control unit 6 of the air conditioner 1 according to Modification E reduces 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 to a third opening that is larger than the second opening. As a result, the controller 6 of the air conditioner 1 according to Modification E can increase the opening degree of the utilization expansion valve 32 as the air conditioning operation of the air conditioner 1 is performed at a lower load. Since the choke phenomenon is more likely to occur as the air conditioning operation is performed at a lower load, according to the air conditioner 1 according to the modification E, in the reheat dehumidification operation, the utilization expansion valve 32 whose opening is throttled causes the refrigerant circuit to A choke phenomenon that hinders the flow of the coolant is effectively suppressed.

(5-6) Modification F
In the air conditioner 1 according to Modification F, when the predetermined condition is established, the controller 6 increases the rotational speed of the compressor 21 compared to when the predetermined condition is not established. Specifically, the control unit 6 of the air conditioner 1 according to Modification E increases the number of revolutions of the motor 22 when the predetermined condition is satisfied than when the predetermined condition is not satisfied.

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

Although embodiments of the present disclosure have been described above, it will be appreciated that various changes in form and detail may be made without departing from the spirit and scope of the present disclosure as set forth in the appended 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 first utilization heat exchange section 312 second utilization heat Replacement part 32 utilization expansion valve (expansion valve)
33 Fans used (fans)
4 Liquid refrigerant communication pipe 5 Gas refrigerant communication pipe 6 Control unit 7 Remote controller Te Temperature of second heat exchange unit 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

JP-A-2003-314854

Claims (5)

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 use heat exchange section (311), an expansion valve (32), and a second use heat exchange section (312) are annularly connected. and,
a control unit (6) for executing a reheat dehumidification operation by controlling the refrigerant circuit to cause the first heat-utilization exchange unit to function as a condenser and the second heat-utilization heat-exchange unit to function as an evaporator; with
The expansion valve is
The degree of opening is controlled by the control unit,
The control unit
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 lower than the first opening degree. setting a large predetermined second degree of opening, and then setting the degree of opening of the expansion valve to a predetermined first degree of opening or less to continue the reheat dehumidifying operation;
Determining whether the predetermined condition is satisfied based on a first temperature difference (ΔT1), which is a temperature difference between the room temperature (Tr) and the temperature (Te) of the second heat exchange unit,
Air conditioner. 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 use heat exchange section (311), an expansion valve (32), and a second use heat exchange section (312) are annularly connected. and,
a control unit (6) for executing a reheat dehumidification operation by controlling the refrigerant circuit to cause the first heat-utilization exchange unit to function as a condenser and the second heat-utilization heat-exchange unit to function as an evaporator; with
The expansion valve is
The degree of opening is controlled by the control unit,
The control unit
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 lower than the first opening degree. setting a large predetermined second degree of opening, and then setting the degree of opening of the expansion valve to a predetermined first degree of opening or less to continue the reheat dehumidifying operation;
Determining whether the predetermined condition is satisfied based on the outside temperature (To);
Air conditioner. 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 use heat exchange section (311), an expansion valve (32), and a second use heat exchange section (312) are annularly connected. and,
a control unit (6) for executing a reheat dehumidification operation by controlling the refrigerant circuit to cause the first heat-utilization exchange unit to function as a condenser and the second heat-utilization heat-exchange unit to function as an evaporator; ,
A fan (33) that blows air to the first heat utilization unit and the second heat utilization unit,
The expansion valve is
The degree of opening is controlled by the control unit,
The control unit
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 lower than the first opening degree. setting a large predetermined second degree of opening, and then setting the degree of opening of the expansion valve to a predetermined first degree of opening or less to continue the reheat dehumidifying operation;
Determining whether the predetermined condition is satisfied based on the number of revolutions (Ra) of the fan;
Air conditioner. The control unit
temporarily increasing the degree of opening of the expansion valve to be greater than the second degree of opening when the first temperature difference is less than or equal to a predetermined threshold temperature difference (ΔTth3);
The air conditioner according to claim 1. The control unit
When the predetermined condition is established, the number of revolutions of the compressor is increased more than when the predetermined condition is not established.
The air conditioner according to any one of claims 1 to 4.

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