JPH10311586A - Air-conditioning apparatus for combination cooling and heating and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air-conditioning apparatus for combination cooling and heating to prevent the occurrence of excessive cooling in a room during dehumidification operation and improve dehumidification and prevent lowering of temperature in a room occurring during defrosting operation, and to provide a control method therefor. SOLUTION: In an air-conditioner for combination cooling and heating, an indoor heat-exchanger 13 comprises first and second heat exchange parts 15 and 17 coupled with each other in series; and an auxiliary expansion valve 23 arranged between the two heat-exchanger 15 and 17. A control part circulates a refrigerant through a cooling cycle or a heating cycle and meanwhile, the opening of a main expansion valve 35 is decreased and the auxiliary expansion valve 23 is brought into a full opening state to perform cooling operation and heating operation, A refrigerant is circulated through the heating cycle and meanwhile, the main expansion valve 35 is brought into a full opening state and the opening of the auxiliary expansion valve 23 is decreased to effect dehumidification operation. This constitution prevents the occurrence of supercooling of an indoor temperature during dehumidification operation and improves dehumidification efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling / heating air conditioner and a control method thereof, and more particularly to a cooling / heating air conditioning device capable of preventing overcooling of a room during dehumidification operation and improving dehumidification efficiency and a control method thereof.

[0002]

2. Description of the Related Art Generally, a cooling / heating air conditioner has a refrigerant circulation system in which a compressor, an indoor heat exchanger, a main expansion valve, and an outdoor heat exchanger are sequentially connected in series through a refrigerant pipe to form a closed loop. A conversion valve is provided for selectively supplying the refrigerant flowing out of the compressor toward one of the outdoor heat exchanger and the indoor heat exchanger. During the heating operation, the refrigerant from the compressor is supplied to the indoor heat exchanger to form a heating cycle, and during the cooling operation,
Refrigerant from the compressor is supplied to the outdoor heat exchanger to form a cooling cycle.

[0003] These air conditioners that are used for both cooling and heating have a dehumidifying operation mode for removing moisture contained in indoor air in addition to the cooling and heating operation. In the dehumidifying operation, the refrigerant is circulated in a cooling cycle so that the surface temperature of the indoor heat exchanger becomes equal to or lower than the dew point temperature of air, and moisture in the air in contact with the indoor heat exchanger is removed. Such a dehumidifying operation is performed when room air humidity is high but indoor cooling is not required. Therefore, the indoor blower fan is stopped or operated at a low speed.

However, there is a problem that the cool air cooled around the indoor heat exchanger is inevitably supplied to the room, whereby the room temperature can be excessively cooled. Since the blower fan rotates at a low speed, the heat transfer efficiency of the indoor heat exchanger is low. As a result, there is a problem that the dehumidification efficiency is reduced and it takes a long time to dehumidify to a desired humidity.

[0005] On the other hand, during the heating operation performed in winter, a relatively large amount of frost is generated on the surface of the outdoor heat exchanger functioning as an evaporator in association with the low external temperature, and intermittent operation is required to remove the frost. The defrosting operation is performed. Since this defrosting operation is performed by circulating the refrigerant in a cooling cycle,
Cool air is inevitably formed around the indoor heat exchanger, which inevitably lowers the indoor temperature and lowers the heating efficiency.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a conventional dehumidifying operation in consideration of the above problems.
An object of the present invention is to provide a cooling / heating combined air conditioner capable of preventing indoor undercooling and improving dehumidification efficiency, and a control method thereof.

It is another object of the present invention to provide a cooling / heating combined air conditioner and a control method therefor, which can prevent a temperature drop in a room caused during a defrosting operation.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a closed-loop refrigerant circulation system in which a compressor, an indoor heat exchanger, a main expansion valve, and an outdoor heat exchanger are sequentially connected in series through a refrigerant pipe. A switching valve for selecting a heating cycle in which the refrigerant from the compressor is supplied to the indoor heat exchanger and a cooling cycle in which the refrigerant is supplied to the outdoor heat exchanger; and the indoor heat exchanger and the outdoor heat. An indoor fan and an outdoor fan respectively attached to the exchanger; and a control unit for controlling the compressor, the valve and the fan, wherein the indoor heat exchangers are connected in series with each other. A first heat exchange unit and a second heat exchange unit; and an auxiliary expansion valve disposed between the two heat exchange units, wherein the control unit circulates refrigerant in a cooling cycle or a heating cycle. On the other hand, the opening degree of the main expansion valve is reduced, the auxiliary expansion valve is fully opened to perform the cooling operation and the heating operation, and the refrigerant is circulated in the heating cycle, while the main expansion valve is fully opened. This is achieved by a cooling / heating air conditioner characterized by performing a dehumidifying operation by reducing the opening of the auxiliary expansion valve.

[0009] The fuel cell system further includes a bypass pipe branched from a refrigerant pipe between the main expansion valve and the outdoor heat exchanger and connected to the compressor; and a bypass valve disposed in the bypass pipe. It is preferable that the control unit opens the bypass valve during the dehumidifying operation. At this time, when the control unit operates the indoor fan during the dehumidification operation and stops the outdoor fan, the dehumidification efficiency can be improved.

[0010] Then, the control unit, during the heating operation,
When a predetermined defrosting operation condition is reached, the refrigerant circulation is switched to a cooling cycle, the main expansion valve is closed, and the bypass valve is opened to perform the defrosting operation of the outdoor heat exchanger. Can be accomplished.

In this case, the control unit may further include an outdoor temperature sensor for detecting an outdoor temperature, and an outdoor pipe temperature sensor for detecting a temperature of an outdoor pipe between the main expansion valve and the outdoor heat exchanger. During operation, when the temperature difference between the outdoor temperature and the outdoor pipe temperature is equal to or more than a predetermined value, it is determined that the defrosting operation condition has been reached, and a defrosting operation is performed,
On the other hand, when the temperature of the outdoor pipe becomes equal to or higher than a predetermined temperature, it is preferable that the defrosting operation is determined to end when the defrosting operation is completed, and the heating operation is restarted. Here, it is more desirable to provide a predetermined rest period in which the operation of the compressor is stopped between the end of the defrosting operation and the restart of the heating operation. If the indoor fan and the outdoor fan are stopped during such a defrosting operation, it is possible to prevent a temperature drop in the room.

On the other hand, an indoor pipe temperature sensor for detecting a temperature of an indoor pipe between the auxiliary expansion valve and the second heat exchange section, and a temperature of an inflow pipe for detecting a temperature of a refrigerant inflow pipe to the compressor. A control unit that controls the auxiliary expansion valve during the dehumidifying operation so that a temperature difference between the temperature of the inflow pipe and the temperature of the indoor pipe is within a predetermined allowable range. It is desirable to do. Such control may include reducing the opening of the auxiliary expansion valve when the temperature difference is equal to or lower than the lower limit of the allowable range, and increasing the opening of the auxiliary expansion valve when the temperature difference is equal to or higher than the upper limit of the allowable range. Is possible.

An indoor pipe temperature sensor for detecting a temperature of an indoor pipe between the auxiliary expansion valve and the second heat exchange section, an inflow pipe temperature sensor for detecting a temperature of a refrigerant inflow pipe to the compressor, Preferably, the control unit controls the main expansion valve during a cooling operation so that a temperature difference between the temperature of the inflow pipe and the temperature of the indoor pipe is within a predetermined allowable range. . Such control is
This can be achieved by reducing the opening of the main expansion valve when the temperature difference is lower than the lower limit of the allowable range, and increasing the opening of the main expansion valve when the temperature difference is higher than the upper limit of the allowable range.

An outdoor pipe temperature sensor for detecting a temperature of an outdoor pipe between the main expansion valve and the outdoor heat exchanger;
An inlet pipe temperature sensor for sensing a temperature of a refrigerant inlet pipe to the compressor, wherein the controller controls the main expansion valve during cooling operation to control the temperature of the inlet pipe and the temperature of the outdoor pipe. It is desirable that the temperature difference from the temperature be within a predetermined allowable range. Such control may include reducing the opening of the main expansion valve when the temperature difference is equal to or less than the lower limit of the allowable range, and increasing the opening of the main expansion valve when the temperature difference is equal to or more than the upper limit of the allowable range. By
It is possible.

[0015] It is preferable that the second heat exchanging section is disposed upstream of the first heat exchanging section.

According to another aspect of the present invention, there is provided a refrigerant circulation system in which a compressor, an indoor heat exchanger, a main expansion valve, and an outdoor heat exchanger are sequentially connected in series through a refrigerant pipe to form a closed loop. A switching valve for selecting a heating cycle in which the refrigerant from the compressor is supplied to the indoor heat exchanger and a cooling cycle in which the refrigerant is supplied to the outdoor heat exchanger; and the indoor heat exchanger and the outdoor heat. In a method for controlling an air conditioner that has both an indoor fan and an outdoor fan attached to an exchanger, the indoor heat exchanger is divided into a first heat exchange unit and a second heat exchange unit connected in series with each other. An auxiliary expansion valve is disposed between the heat exchanging units to circulate the refrigerant in the heating cycle, while the main expansion valve is fully opened and the opening of the auxiliary expansion valve is reduced to perform the dehumidifying operation. It is achieved by the control method of cooling and heating combined air-conditioning equipment, which comprises a that step.

Here, in the dehumidifying operation, the method may further include a step of bypassing the refrigerant from a refrigerant pipe between the main expansion valve and the outdoor heat exchanger to the compressor. it can. At this time, it is desirable to operate the indoor fan and stop the outdoor fan.

On the other hand, when a predetermined defrosting operation condition is reached during the heating operation, the refrigerant circulation is switched to the cooling cycle and the main expansion valve is shut off, while opening the bypass valve causes the outdoor heat exchange. The defrosting operation of the vessel can be performed.

The method may further include: sensing an outdoor temperature; and sensing a temperature of an outdoor pipe between the main expansion valve and the outdoor heat exchanger, during the heating operation.
When the temperature difference between the outdoor temperature and the outdoor pipe temperature becomes equal to or more than a predetermined value, it can be determined that the defrosting operation condition has been reached. At this time, when the temperature of the outdoor pipe becomes equal to or higher than a predetermined temperature, it is preferable that the method further includes a step of judging a defrost ending point to end the defrosting operation and restart the heating operation.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the attached drawings. 1 and 2 are schematic configuration diagrams of an air conditioner according to the present invention. FIG. 1 is a diagram illustrating a flow state of a refrigerant during a heating operation and a defrosting operation.
FIG. 4 is a diagram illustrating a flow state of a refrigerant during a cooling operation and a dehumidifying operation. As can be seen from these figures, the present air conditioner 1
Has an outdoor unit 9 and an indoor unit 3 provided on the outdoor side and the indoor side, respectively, and a refrigerant circulation system 11 that connects the outdoor unit 9 and the indoor unit 3 so that the refrigerant can move. The refrigerant circulation system 11 includes a compressor 31, an indoor heat exchanger 1
3. The outdoor heat exchanger 33 and the main expansion valve 35 are connected in series through a refrigerant pipe to form a closed loop.

The outdoor unit 9 provided on the outdoor side includes a compressor 3
1. It has an external casing (not shown) in which the outdoor heat exchanger 33 and the main expansion valve 35 are built. The main expansion valve 35 is installed so as to reduce or increase the opening degree of the refrigerant channel. In the outer casing,
An outdoor temperature sensor 37 for sensing the outdoor temperature is mounted, and the outdoor fan 3 is directed toward the outdoor heat exchanger 33.
9 are provided. As shown in FIG. 3, the indoor unit 3 on the indoor side has an intake port 4 opened upward and an outer casing 6 having a discharge port 5 opened forward,
And an indoor heat exchanger 13 provided in the outer casing 6. An electric precipitator 19 is provided on an opening surface of the intake port 4.

The indoor heat exchanger 13 is divided into a second heat exchange section 17 corresponding to the intake port 4 and a first heat exchange section 15 corresponding to the discharge port 5. The heat exchanging parts 15 and 17 can be manufactured by a general technique using a plurality of heat transfer tubes and heat transfer fins. One side longitudinal edge faces each other, and the other side longitudinal edge has a predetermined edge. Maintain spacing. An indoor fan 21 is provided between the heat exchange units 15 and 17 forming a predetermined angle. An auxiliary expansion valve 23 is provided at a predetermined position of the indoor pipe between the first heat exchange unit 15 and the second heat exchange unit 17 to reduce or increase the degree of opening of the refrigerant passage. it can. Auxiliary expansion valve 23 and second heat exchange section 1
7, an indoor pipe temperature sensor 25 for detecting the temperature of the indoor pipe is provided.

On the other hand, a refrigerant outflow pipe 51 from the compressor 31 and a refrigerant inflow pipe 53 to the compressor 31 among the refrigerant pipes forming the refrigerant circulation system 11 are mutually connected at a predetermined position adjacent to the compressor 31. It is connected. At this connection position, a conversion valve 55 for forming a refrigerant flow path from the compressor 31 toward the outdoor heat exchanger 33 or the indoor heat exchanger 13
Is provided. The conversion valve 55 is connected to the outdoor heat exchanger 33.
When opened toward the indoor heat exchanger 13, a cooling cycle that changes the air around the indoor heat exchanger 13 into cool air is formed, as described later in detail. It is formed.

An outdoor pipe temperature sensor 41 for sensing the temperature is provided in the outdoor pipe adjacent to the outdoor heat exchanger 33 downstream of the main expansion valve 35. An inflow pipe temperature sensor 43 is provided in the refrigerant inflow pipe 53 adjacent to the compressor 31. Further, a bypass pipe 57 having one end connected to the refrigerant flow path between the main expansion valve 35 and the outdoor heat exchanger 33 and the other end connected to the refrigerant inflow pipe 53 is provided here. . The bypass pipe 57 has a bypass valve 59 for opening and closing the refrigerant flow path.
Is provided.

The air conditioner 1 according to the present invention having such a configuration has a control unit 61 composed of a microcomputer as seen from FIG. An operation signal from the operation unit 63 is applied to the control unit 61, and temperature sensing signals from the inflow pipe temperature sensor 43, the indoor pipe temperature sensor 25, the outdoor pipe temperature sensor 41, and the outdoor temperature sensor 37 are applied. You. Then, based on these applied signals, the components of the refrigerant circulation system, that is, the operation of the compressor 31, the indoor fan 21, the outdoor fan 39, the main expansion valve 35, the auxiliary expansion valve 23, the conversion valve 55, the bypass valve 59, etc. Control. The control signal from the control unit 61 is transmitted through a drive circuit attached to each component.
Then, the temperature setting state and the operation state of the device are displayed through the display unit 65.

Hereinafter, a method for controlling an air conditioner according to the present invention will be described with reference to the control flowcharts of FIGS. The air conditioner 1 according to the present invention can perform a heating operation, a cooling operation, and a dehumidification operation through an operation selection key (not shown) provided on the operation unit 63. FIG. 5 is a control flowchart for the heating operation performed when the user selects the heating operation, and the control flowchart includes a defrosting operation. When the operation is started (Q1), the control unit 61 confirms the operation state selected by the user (Q2). First, it is confirmed whether the heating operation is selected (Q3), and if it is selected, the corresponding operation is performed (S3).
1). If the heating operation is not selected, the cooling operation and the dehumidifying operation are checked in this order (Q4, Q5). If none of these operations is selected, it is confirmed (Q6) whether the operation can be selected until a predetermined time has elapsed. If the operation is not selected even after a predetermined time, the operation of the device is stopped (Q7).

When the heating operation is selected (S 1), the control unit 61 first opens the conversion valve 55 in the direction of the indoor heat exchanger 13, opens the auxiliary expansion valve 23 to the fully opened state, and turns off the main expansion valve 35. The opening is reduced and the bypass valve 59 is closed (S2). Next, the compressor 3
1 is driven (S3), the refrigerant moves according to the heating cycle as shown by the solid arrow in FIG.

That is, the high-temperature and high-pressure gaseous refrigerant compressed in the compressor 31 moves to the indoor heat exchanger 13 and is condensed in the first heat exchange section 15 and the second heat exchange section 17 and is cooled in the low-temperature and high-pressure liquid state. Becomes a refrigerant. At this time, the temperature of the air around the first and second heat exchangers 15 and 17 rises due to the latent heat of condensation from the refrigerant. On the other hand, the liquid refrigerant including the gaseous refrigerant condensed in the indoor heat exchanger 13 is condensed while passing through the main expansion valve 35 and is provided to the outdoor heat exchanger 33 in a low-temperature and low-pressure liquid state. In the outdoor heat exchanger 33, the liquid refrigerant evaporates and absorbs the latent heat from the external air. At this time, the temperature of the external air that has lost the latent heat decreases. Accordingly, frost is formed on the surface of the outdoor heat exchanger 33 due to a temperature difference between the outdoor heat exchanger 33 and surrounding air. The gaseous refrigerant that has passed through the outdoor heat exchanger 33 is provided to the compressor 31, where it is compressed again and circulates through the heating cycle.

During the operation of the compressor 31, the indoor fan 21 and the outdoor fan 39 are driven (S4). The indoor fan 21 and the outdoor fan 39 improve the efficiency of heat exchange between the indoor heat exchanger 13 and the outdoor heat exchanger 33 and the surrounding air. At this time, the indoor fan 21 supplies the warm air formed around the indoor heat exchanger 13 to the room,
Heat the room.

On the other hand, during the heating operation, the temperature sensing signals from the outdoor temperature sensor 37, the inflow pipe temperature sensor 43, and the outdoor pipe temperature sensor 41 are applied to the control unit 61, and the temperatures (T _air , T _{air) of} the corresponding area are applied. _s, T _o) to sense the (S5).
Then, when the temperature difference by comparing the outdoor temperature T _air and the outdoor pipe temperature T _o is equal to or greater than 10 ° C. (S6), and compares the refrigerant inlet pipe temperature T _s and the outdoor pipe temperature T _o (S7). Then, the temperature difference between the refrigerant inflow pipe 53 and the outdoor pipe is 5 ° C.
If it is within the range of the predetermined tolerance (α), the current state is maintained as it is (S8). Then, the operation selection state is confirmed (Q2), and the operation corresponding to the operation selection state is repeatedly performed. However, when the temperature difference exceeds 5 ° C. + a predetermined allowable value (α), the opening degree of the main expansion valve 35 is increased (S11), and the condensing rate of the refrigerant is slightly reduced to reduce the temperature by 5 ° C.−
If it is less than the predetermined allowable value (α), the main expansion valve 35
Is decreased (S10) to increase the condensation rate of the refrigerant. Thereafter, based on the applied temperature sensing signal (S5), the above-described heating operation is continuously performed.

On the other hand, when the temperature difference between the outdoor temperature T _air and the outdoor pipe temperature T _o is 10 ° C. or less (S6), the defrosting operation for the removal of Shimomon that is frosted outdoor heat exchanger 33 Performed (P1). At this time, the control unit 61 controls the conversion valve 55
Is opened toward the outdoor heat exchanger 33, the opening degree of the main expansion valve 35 is reduced to be in a shut-off state, and the bypass valve 59 is opened (P2). Then, the refrigerant moves according to a short closed loop as shown by a broken arrow in FIG. That is, the high-temperature and high-pressure refrigerant compressed by the compressor 31 flows into the outdoor heat exchanger 33 to melt the frost pattern formed on the surface and return to the compressor 31 through the bypass pipe 57. Then, the refrigerant condensed in the outdoor heat exchanger 33 is not supplied to the indoor heat exchanger 13, so that the refrigerant is not evaporated in the indoor heat exchanger 13, thereby preventing the indoor temperature from lowering. At this time, it is desirable to stop driving the indoor fan 21 and the outdoor fan 39 (P3).

On the other hand, during such a defrosting operation, the controller 61 controls the outdoor pipe temperature T through the outdoor pipe temperature sensor 41.
_o is sensed (P4). Then, the outdoor pipe temperature T _o is about 1
The defrost operation is performed until the temperature reaches 0 ° C. or more (P5). When the outdoor piping temperature T _o is equal to or greater than 10 ° C., the compressor 31 is stopped for about 2 minutes (P6), resumes the heating operation (S1).

FIG. 6 is a control flowchart for the cooling operation in FIG. When the cooling operation is selected by the user (T1), the control unit 61 opens the conversion valve 55 in the direction of the outdoor heat exchanger 33, and opens the main expansion valve 35.
, The auxiliary expansion valve 23 is fully opened, and the bypass valve 59 is shut off (T2). Next, when the compressor 31 is driven (T3), the refrigerant moves in accordance with the cooling cycle which is the opposite direction to the heating cycle, as shown by the broken arrow in FIG. Then, the refrigerant is condensed in the outdoor heat exchanger 33, and evaporated in the indoor heat exchanger 13, and the first and second heat exchangers 15,
Cool air is formed around 17. Such cool air is supplied into the room by the driving of the indoor fan 21 to cool the room (T4).

[0034] During the cooling operation, the control unit 61, the temperature sensing signal from the inlet pipe temperature sensor 43 and the indoor piping temperature sensor 25 is applied to sense the refrigerant inlet pipe temperature T _s and the indoor piping temperature T _i ( T5). Then, these temperatures are compared (T6), and the temperature difference is 5 ° C. ± the predetermined allowable value (α).
If it is within the range, the current state is maintained as it is (T7). Then, reconfirm the selection of operation (Q
2) Perform the corresponding operation. However, the temperature difference is 5 ° C
+ If the predetermined tolerance (α) is exceeded, the main expansion valve 3
If the degree of condensation of the refrigerant is slightly reduced by increasing the opening of (5) (T9) and becomes equal to or less than 5 ° C-a predetermined allowable value (α), the opening of the main expansion valve 35 is decreased (T10). Increase the condensation rate of Thereafter, based on the applied temperature sensing signal (T5), the above-described cooling operation is continuously performed.

FIG. 7 is a control flowchart at the time of the dehumidifying operation of FIG. When the dehumidifying operation is selected by the user (U1), the control unit 61 opens the conversion valve 55 in the direction of the indoor heat exchanger 13 while keeping the main expansion valve 35 in the fully opened state and reducing the opening of the auxiliary expansion valve 23. At the same time, the bypass valve 59 is opened (U2). Next, when the compressor 31 is driven (U3), the refrigerant moves according to the heating cycle as shown by the solid arrow in FIG. 1 as in the heating operation.

That is, the high-temperature and high-pressure gaseous refrigerant compressed in the compressor 31 moves to the indoor heat exchanger 13 and is condensed in the first heat exchange unit 15 to become a low-temperature and high-pressure liquid refrigerant. At this time,
The condensed refrigerant is deprived of the latent heat of condensation by the air around the first heat exchange unit 15, and thereby the surrounding air becomes warm. The refrigerant flowing out of the first heat exchange unit 15 is condensed by the auxiliary expansion valve 23, and then provided to the second heat exchange unit 17 to evaporate. The evaporating refrigerant absorbs the surrounding latent heat and turns the surrounding air into cool air. At this time, the water vapor contained in the air around the second heat exchange unit 17 is saturated and the second heat exchange unit 17
Condensation on the surface. As a result, the air around the second heat exchange section 17 maintains the humidity at which the dewed amount of moisture has been removed. The refrigerant that has passed through the second heat exchange section 17 flows into the compressor 31 via the bypass valve 59, is compressed, and circulates again in the heating cycle.

During the operation of the compressor 31, the indoor fan 21 is driven (U4). Then, the air sucked into the intake port 4 of the indoor unit 1 loses latent heat in the second heat exchange unit 17 arranged on the upstream side of the flow path, and its temperature decreases, and at this time, the absolute humidity decreases. Then, the temperature rises due to heat exchange with the first heat exchange section 15 on the downstream side, and eventually the temperature is almost the same as that of the room and the liquid is discharged.

On the other hand, during the dehumidifying operation, the temperature sensing signals from the inflow pipe temperature sensor 43 and the indoor pipe temperature sensor 25 are applied to the controller 61, and the temperatures (T _s , T _i ) of the corresponding area are applied.
Is sensed (U5). Then these temperatures (T _s ,
T _i ) are compared (U6), and if the temperature difference is within the range of 5 ° C. ± the predetermined allowable value (α), the current state is maintained (U7). Next, the operation selection state is reconfirmed (Q2), and the corresponding operation is performed. However, if the temperature difference exceeds 5 ° C. + the predetermined allowable value (α), the opening degree of the auxiliary expansion valve 23 is increased (U9) to slightly reduce the condensation rate of the refrigerant, and 5 ° C.−the predetermined allowable value (α). (Α) or less, the opening degree of the auxiliary expansion valve 23 is reduced (U1
0) Increase the refrigerant condensation rate. Thereafter, based on the applied temperature sensing signal (U5), the above-described dehumidifying operation is continuously performed.

As described above, in the present cooling / heating air conditioner and its control method, the air flowing into the air inlet 4 during the dehumidifying operation is dehumidified by the second heat exchanging unit 17 and then the first heat exchanging unit 15 Is discharged at almost the same temperature as in the room by the heat exchange, so that the room temperature is prevented from being excessively cooled. When the indoor fan 21 is rotated at a high speed, the dehumidification efficiency in the second heat exchange unit 17 is increased by the increase in the flow velocity of the air. At this time, the condensation efficiency is improved in the first heat exchange unit 15 and the air is discharged indoors. The temperature change almost disappears. Therefore, the dehumidification time can be shortened and the dehumidification efficiency can be improved by increasing the flow velocity.

In the cooling / heating air conditioner and the control method therefor, the refrigerant from which the frost pattern formed on the surface of the outdoor heat exchanger 33 has been removed during the defrosting operation is not supplied to the indoor heat exchanger 13, so that the indoor heat exchanger 13 is not supplied. Is prevented from lowering.

[0041]

As described above, according to the present invention, there is provided a cooling / heating combined air-conditioning apparatus which can prevent the room from being overcooled during the dehumidifying operation, and at the same time improve the dehumidifying efficiency, and a control method thereof. Then, it is possible to prevent the room temperature from decreasing even during the defrosting operation.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air conditioner according to the present invention, illustrating a flow state of a refrigerant during a heating operation and a defrosting operation.

FIG. 2 is a diagram illustrating a flow state of a refrigerant during a cooling operation and a dehumidifying operation in FIG. 1;

FIG. 3 is a cross-sectional view of the indoor unit of FIG.

FIG. 4 is a control block diagram of an air conditioner according to the present invention.

FIG. 5 is a control flowchart during a heating operation and a defrosting operation in FIG. 1;

FIG. 6 is a control flowchart at the time of a cooling operation in FIG. 2;

FIG. 7 is a control flowchart at the time of a dehumidifying operation in FIG. 2;

[Explanation of symbols]

Reference Signs List 3 indoor unit 9 outdoor unit 11 refrigerant circulation system 13 indoor heat exchanger 15 first heat exchange unit 17 second heat exchange unit 21 indoor fan 23 auxiliary expansion valve 25 indoor piping temperature sensor 31 compressor 33 outdoor heat exchanger 35 main expansion Valve 37 Outdoor temperature sensor 39 Outdoor fan 41 Outdoor piping temperature sensor 43 Inflow piping temperature sensor 53 Refrigerant inflow piping 55 Conversion valve 57 Bypass pipe 59 Bypass valve 61 Control unit T _air outdoor temperature T _i Indoor piping temperature T _o Outdoor piping temperature T _s Refrigerant inflow pipe temperature

Claims (21)

[Claims] 1. a compressor, an indoor heat exchanger, a main expansion valve,
And a refrigerant circulation system in which an outdoor heat exchanger is sequentially connected in series through a refrigerant pipe to form a closed loop; refrigerant from the compressor is supplied to the indoor heat exchanger and a heating cycle and supplied to the outdoor heat exchanger. A conversion valve for selecting a cooling cycle to be performed; an indoor fan and an outdoor fan respectively attached to the indoor heat exchanger and the outdoor heat exchanger; and a control unit for controlling the compressor, the valve, and the fan. In the air conditioner having both cooling and heating, the indoor heat exchanger includes a first heat exchange unit and a second heat exchange unit connected in series with each other, and an auxiliary expansion valve arranged between the heat exchange units. The control unit circulates the refrigerant in a cooling cycle or a heating cycle, while reducing the opening degree of the main expansion valve and setting the auxiliary expansion valve in a fully open state to perform cooling operation and heating operation. While each execution, and the refrigerant is circulated in the heating cycle,
The air conditioner for both cooling and heating, wherein the main expansion valve is fully opened and the degree of opening of the auxiliary expansion valve is reduced to perform a dehumidifying operation. 2. A bypass pipe branched from a refrigerant pipe between the main expansion valve and the outdoor heat exchanger and connected to the compressor; and a bypass valve disposed in the bypass pipe. The air conditioner for cooling and heating according to claim 1, wherein the controller opens the bypass valve during the dehumidifying operation. 3. The air conditioner according to claim 2, wherein the controller operates the indoor fan and stops the outdoor fan during the dehumidifying operation. 4. When the controller reaches a predetermined defrosting operation condition during the heating operation, the control unit switches the refrigerant circulation to a cooling cycle, shuts off the main expansion valve, and turns off the bypass valve. 2. The air conditioner for cooling and heating according to claim 1, wherein a defrosting operation of the outdoor heat exchanger is performed in an open state. 5. An outdoor temperature sensor for detecting an outdoor temperature, and an outdoor pipe temperature sensor for detecting a temperature of an outdoor pipe between the main expansion valve and the outdoor heat exchanger, wherein the control unit performs a heating operation. The air conditioner according to claim 4, wherein when the temperature difference between the outdoor temperature and the outdoor pipe temperature becomes equal to or more than a predetermined value, it is determined that the defrosting operation condition has been reached. . 6. The controller according to claim 6, wherein when the outdoor pipe temperature is equal to or higher than a predetermined temperature, the controller determines that the defrosting is completed and ends the defrosting operation and restarts the heating operation. 6. The air conditioner for cooling and heating according to 5. 7. The apparatus according to claim 6, wherein a predetermined suspension period during which the operation of the compressor is stopped is provided between the end of the defrosting operation and the restart of the heating operation. The combined air conditioning and heating air conditioner described. 8. The air conditioner for cooling and heating according to claim 4, wherein the indoor fan and the outdoor fan are stopped during the defrosting operation. 9. An indoor pipe temperature sensor for sensing a temperature of an indoor pipe between the auxiliary expansion valve and the second heat exchange section, and an inflow pipe temperature sensor for detecting a temperature of a refrigerant inflow pipe to the compressor. The control unit controls the auxiliary expansion valve during the dehumidifying operation so that a temperature difference between the inflow pipe temperature and the indoor pipe temperature is within a predetermined allowable range. The air conditioner for cooling and heating according to claim 1. 10. The control unit reduces the opening of the auxiliary expansion valve when the temperature difference is less than the lower limit of the allowable range, and reduces the opening of the auxiliary expansion valve when the temperature difference is equal to or more than the upper limit of the allowable range. 10. The method according to claim 9, wherein
The air-conditioning equipment for both cooling and heating described in 1. 11. An indoor pipe temperature sensor for detecting a temperature of an indoor pipe between the auxiliary expansion valve and the second heat exchange section, and an inflow pipe temperature sensor for detecting a temperature of a refrigerant inflow pipe to the compressor. The control unit controls the main expansion valve during a cooling operation so that a temperature difference between the inflow pipe temperature and the indoor pipe temperature is within a predetermined allowable range. The air conditioner for cooling and heating according to claim 1. 12. The controller according to claim 1, wherein the controller is configured to reduce an opening of the main expansion valve when the temperature difference is equal to or less than a lower limit of the allowable range, and to set an opening of the main expansion valve when the temperature difference is equal to or more than an upper limit of the allowable range. The cooling / heating combined air-conditioning apparatus according to claim 11, wherein 13. An outdoor pipe temperature sensor for sensing a temperature of an outdoor pipe between a main expansion valve and the outdoor heat exchanger;
An inlet pipe temperature sensor for sensing a temperature of a refrigerant inlet pipe to the compressor, wherein the control unit controls the main expansion valve to control the temperature of the inlet pipe and the temperature of the outdoor pipe during a heating operation. 2. The air conditioner for cooling and heating according to claim 1, wherein the temperature difference from the temperature is within a predetermined allowable range. 14. The control unit decreases the opening of the main expansion valve when the temperature difference falls below the lower limit of the allowable range, and opens the opening of the main expansion valve when the temperature difference exceeds the upper limit of the allowable range. 14. The air conditioner for cooling and heating according to claim 13, wherein 15. The air conditioner for cooling and heating according to claim 1, wherein the second heat exchange unit is disposed upstream of the first heat exchange unit. 16. A closed-loop refrigerant circulation system in which a compressor, an indoor heat exchanger, a main expansion valve, and an outdoor heat exchanger are sequentially connected in series through a refrigerant pipe to form a closed loop; A conversion valve for selecting a heating cycle supplied to the exchanger and a cooling cycle supplied to the outdoor heat exchanger; and an indoor fan and an outdoor fan respectively attached to the indoor heat exchanger and the outdoor heat exchanger;
In the method for controlling a cooling / heating air conditioner, the indoor heat exchanger is divided into a first heat exchange unit and a second heat exchange unit connected in series with each other, and an auxiliary expansion valve is provided between the two heat exchange units. And controlling the air conditioner for both cooling and heating while performing a dehumidifying operation by fully opening the main expansion valve and reducing the opening of the auxiliary expansion valve while circulating the refrigerant in the heating cycle. Method. 17. The method according to claim 16, further comprising, during the dehumidifying operation, bypassing the refrigerant from a refrigerant pipe between the main expansion valve and the outdoor heat exchanger to the compressor. The control method of the air conditioner for both cooling and heating described in the above. 18. The method according to claim 17, wherein, during the dehumidifying operation, the indoor fan is operated to stop the outdoor fan. 19. When a predetermined defrosting operation condition is reached during the heating operation, the refrigerant circulation is switched to the cooling cycle, the main expansion valve is shut off, and the bypass valve is opened to open the outdoor heat source. The method of claim 16, further comprising performing a defrosting operation of the exchanger. 20. The method according to claim 20, further comprising: sensing an outdoor temperature; and sensing a temperature of an outdoor pipe between the main expansion valve and the outdoor heat exchanger. The method according to claim 17, further comprising: determining that the defrosting operation condition has been reached when a temperature difference from the outdoor pipe temperature becomes equal to or more than a predetermined value. 21. The method according to claim 20, further comprising, when the temperature of the outdoor pipe becomes equal to or higher than a predetermined temperature, determining that the defrosting is completed and terminating the defrosting operation and restarting the heating operation. 3. The method for controlling an air conditioner for both cooling and heating according to item 1.