JP2998739B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner capable of performing a reheating dry operation in addition to a cooling / heating operation.

[0002]

2. Description of the Related Art For example, in a separate type air conditioner, an indoor heat exchanger, a decompression mechanism, and an outdoor heat exchanger are sequentially connected to a compressor to form a refrigerant circulation circuit, and refrigerant discharged from the compressor is subjected to indoor heat exchange. The heating operation is performed by circulating the air from the heat exchanger to the outdoor heat exchanger, and the cooling operation is performed by circulating the air from the outdoor heat exchanger to the indoor heat exchanger. In this case, the indoor heat exchanger is divided into a first indoor heat exchanger and a second indoor heat exchanger, and a decompression mechanism for dehumidification is interposed between these two heat exchangers to reduce the room temperature. Dehumidification operation can be suppressed.

An example of such an air conditioner is disclosed in
No. 3580. In the air conditioner shown in FIG. 4, the rotation speed of the outdoor fan 51 is reduced, the first opening / closing valve 53 connected in parallel to the pressure reducing mechanism 52 is opened, and the first and second indoor heat exchangers 54 are provided. The second on-off valve 56 between 55 is closed, and the refrigerant is circulated as shown by the solid line arrow in the figure to perform the dehumidification operation. At this time, the refrigerant discharged from the compressor 57 passes through the outdoor heat exchanger 58, is radiated and condensed in the first indoor heat exchanger 54, is decompressed by the dehumidifying decompression mechanism 59, and is then decompressed. Endothermic evaporation.

Therefore, by arranging the second indoor heat exchanger 55 and the first indoor heat exchanger 54 in this order along the direction of air flow in the indoor unit, the indoor air firstly becomes the second indoor heat exchanger. When passing through the exchanger 55, it is cooled, and at this time, moisture is dewed and dehumidified. Next, the air is reheated and blown into the room when passing through the first indoor heat exchanger 54, and the dehumidifying operation in which a decrease in room temperature is suppressed (hereinafter, referred to as a reheating dry operation).
Becomes possible.

[0005] In the air conditioner having the above configuration, the dehumidifying operation is performed in a cooling cycle in which the refrigerant discharged from the compressor 57 is circulated from the outside to the inside of the room. On the other hand, Japanese Patent Publication No. 61-533 discloses an example of an air conditioner that performs a reheat dry operation similar to the above in a heating cycle in which refrigerant discharged from a compressor is circulated from the indoor side to the outdoor side. Have been.

In the air conditioner shown in FIG. 5, the on-off valve 63 between the first indoor heat exchanger 61 and the second indoor heat exchanger 62 is closed, and the refrigerant circulates as shown by the solid arrow in the figure. Then, the dehumidifying operation is performed. At this time, the refrigerant discharged from the compressor 64 passes through the four-way switching valve 65 to the first indoor heat exchanger 61.
And is condensed in this heat exchanger 61. Next, after being depressurized by the dehumidifying decompression mechanism 66, the second indoor heat exchanger 6
Evaporate at 2. Then, after passing through the heating pressure reducing mechanism 67, it is further evaporated in the outdoor heat exchanger 68 and returned to the compressor 64. Therefore, in this case, the second indoor heat exchanger 6
By configuring the indoor air to sequentially pass through the first indoor heat exchanger 61 from the second, the reheat dry operation similar to the above is performed.

In this air conditioner, it is possible to switch to a cooling cycle by a four-way switching valve 65 for switching between cooling and heating. However, even if an attempt is made to perform a dehumidifying operation in this cooling cycle, the direction of air flow in the indoor unit is reduced. Since the second indoor heat exchanger 62 on the upstream side functions as a condenser and the first indoor heat exchanger 61 on the downstream side functions as an evaporator, the reheat dry operation as described above cannot be performed.

That is, in a conventional air conditioner,
Even if a four-way switching valve is provided to enable switching between cooling and heating, the heat exchanger on the downstream side in the ventilation direction in the indoor unit is connected to the compressor, and the upstream heat exchanger is connected to the outdoor heat exchanger. If connected, only the reheat dry operation in the heating cycle can be performed, and as shown in FIG. 4, the heat exchanger on the downstream side in the ventilation direction is on the outdoor heat exchanger side, and the upstream side is on the upstream side. If the heat exchanger is configured so as to be connected to the compressor by pipes, only the reheat dry operation in the cooling cycle can be performed.

[0009]

However, as described above, in the conventional air conditioner in which the reheat dry operation can be performed only in one of the heating cycle and the cooling cycle, the influence of the environmental change such as the outside air temperature. Accordingly, there is a problem that the indoor temperature and the dehumidifying efficiency are likely to be lowered.

That is, in the dehumidifying operation in the cooling cycle as described with reference to FIG. 4, even when the outdoor fan 51 is in a low-speed rotation state or a stopped state, the outdoor heat exchanger 58 is used when the outside air temperature is low. Increases the amount of condensation at An example of a Mollier diagram at this time is shown in FIG. As shown in the figure, when condensation occurs when passing through the outdoor heat exchanger 58, the amount of heat of condensation on the indoor side decreases, and when pressure loss occurs from the outdoor heat exchanger 58 to the indoor side, the indoor side The condensation pressure and the condensation temperature decrease. For this reason, the amount of reheat heat on the indoor side cannot be ensured, and the temperature of the air blown out from the indoor unit decreases.

On the other hand, in the dehumidifying operation in the heating cycle as described with reference to FIG. 5, for example, when the outside air temperature is high, the refrigerant evaporation temperature in the outdoor heat exchanger 68 becomes high. The evaporation temperature in the second indoor heat exchanger 62 before the pressure is reduced by the heating pressure reducing mechanism 67 is further increased. As a result, the temperature of the room air does not drop sufficiently, and the amount of dehumidification is reduced, and the dehumidification efficiency is reduced.

Further, in the conventional separate type air conditioner capable of performing the heating cycle dehumidifying operation, when the connecting pipe for interconnecting the outdoor unit and the indoor unit becomes long, the pressure loss at this point increases. Therefore, there is also a problem that the dehumidifying efficiency is reduced.

That is, for example, in the case of the air conditioner shown in FIG. 5, the first indoor heat exchanger 61 is connected to the four-way switching valve 65 via the gas side communication pipe, and the second indoor heat exchanger 62 is connected to the liquid side. The pipe is connected to the outdoor heat exchanger 68 via a pipe. At this time, when the gas-side communication pipe is formed of, for example, a pipe having an outer diameter of 3/8 inch, the liquid-side communication pipe is, for example, an outer diameter of 1/4 inch. Tubes are used. That is, a pipe having a smaller diameter than the gas-side communication pipe is usually used for the liquid-side communication pipe. When the heating cycle dehumidifying operation is performed in such a pipe connection state, the low-pressure gas refrigerant or the gas-liquid mixed refrigerant evaporated in the second indoor heat exchanger 62 passes through the small-diameter liquid-side connection pipe. Therefore, the pressure loss during this period increases, and the dehumidifying efficiency decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to stably perform a reheat dry operation with good reheat capability and dehumidifying efficiency without being affected by an outdoor environment. It is to provide a possible air conditioner.

[0015]

Therefore, the air conditioner according to the present invention is arranged such that the discharge side and the suction side of the compressor 3 are connected to the secondary side port of the four-way switching valve 7 in which the primary side port is connected respectively. , Sequentially,
The first gas pipe 8, the indoor heat exchanger 20, the first liquid pipe 11, the pressure reducing mechanism 39, the second liquid pipe 13, the outdoor heat exchanger 15, and the second gas pipe 9 are connected to form a refrigerant circulation circuit. The indoor heat exchanger 20 is divided into a first indoor heat exchanger 21 on the first gas pipe 8 side and a second indoor heat exchanger 22 on the first liquid pipe 11 side. Unit 21 and second indoor heat exchanger 2
And a throttle means 23 interposed as a dehumidifying depressurizing mechanism during the dehumidifying operation, and supplies the refrigerant discharged from the compressor 3 to the first gas pipe 8 to supply the first and second indoor heat exchangers 21 and 22 Is used as a condenser and the outdoor heat exchanger 15 functions as an evaporator to perform the heating operation, while the refrigerant discharged from the compressor 3 is supplied to the second gas pipe 9 and the outdoor heat exchanger 15 is used as the condenser, An air conditioner that performs a cooling operation by making the two indoor heat exchangers 21 and 22 function as an evaporator, and discharges refrigerant discharged from the compressor 3 between the first gas pipe 8 and the first liquid pipe 11. In the cooling cycle dehumidifying operation performed by supplying the gas to the second gas pipe 9, the first liquid pipe 11
In the indoor heat exchanger 22, the first indoor heat exchanger 21 maintains the connection state at the time of the cooling / heating operation in which the first indoor heat exchanger 21 is connected to the first gas pipe 8, while the refrigerant discharged from the compressor 3 is connected to the first gas pipe 8. During the heating cycle dehumidifying operation performed by supplying, the first gas pipe 8
The indoor heat exchanger 22 is provided with a connection state switching means 10 for switching to a connection state in which the first indoor heat exchanger 21 is connected to each of the first liquid tubes 11.

According to such a configuration, in both the cooling cycle dehumidifying operation and the heating cycle dehumidifying operation, the refrigerant discharged from the compressor 3 is supplied to the second indoor heat exchanger 22.
And condenses, and evaporates in the first indoor heat exchanger 21. Therefore, by arranging the first indoor heat exchanger 21 on the upstream side and the second indoor heat exchanger 22 on the downstream side along the direction of air flow in the indoor unit, either the cooling cycle or the heating cycle Even reheat dry operation can be performed. Thereby, for example, by appropriately selecting the cooling cycle dehumidifying operation and the heating cycle dehumidifying operation according to environmental changes such as the outside air temperature, the reheating dry operation with good reheating capability and dehumidifying efficiency is more stably performed. Can be made.

In the above description, for example, when the outdoor unit and the indoor unit are connected to each other using a communication pipe, the first indoor heat exchanger 21 is connected to the gas-side communication pipe, and the second indoor heat exchanger 2 is connected.
By connecting the liquid-side communication pipes to each other, the first cycle can be performed during the dehumidifying operation in both the cooling cycle and the heating cycle.
The low-pressure gas refrigerant evaporated in the indoor heat exchanger 21 is sent to the outdoor unit through the gas-side connecting pipe. Therefore, even if the liquid-side connecting pipe is smaller in diameter than the gas-side connecting pipe, the low pressure loss in the connecting pipe, which has occurred in the conventional heating cycle dehumidifying operation, is reduced. Efficiency is improved.

In addition to the above, in the air conditioner of the first aspect, the flow path cross-sectional area of the refrigerant in the first indoor heat exchanger 21 is made larger than the flow path cross-sectional area of the second indoor heat exchanger 22. It is characterized by having.

In this configuration, the cooling / heating capability and the dehumidifying efficiency can be improved. That is, during the heating operation, the high-pressure gas refrigerant flowing into the first indoor heat exchanger 21 gradually condenses into a liquid refrigerant while sequentially passing through the first indoor heat exchanger 21 and the second indoor heat exchanger 22, During the cooling operation, the liquid refrigerant flowing into the second indoor heat exchanger 22 gradually evaporates to become a gas refrigerant, but the flow path cross-sectional area of the first indoor heat exchanger 21 on the side where the proportion of the gas refrigerant is large is increased. By doing this, the first
Pressure loss when passing through the second indoor heat exchangers 21 and 22 is reduced. Thereby, the cooling / heating capability is improved.

On the other hand, in any of the dehumidifying operation of the cooling cycle and the heating cycle, the high-pressure gas refrigerant flows into the second indoor heat exchanger 22 and condenses, and the first indoor heat exchanger 21
The low-pressure liquid refrigerant depressurized by the electric expansion valve 23 for dehumidification flows into and evaporates. Therefore, in this case, the flow path cross-sectional area of the first indoor heat exchanger 21 through which the low-pressure liquid refrigerant or the gas refrigerant flows is larger than that of the second indoor heat exchanger 22, so that the first indoor heat exchanger 22 The low pressure loss at the time of passage 21 decreases. Thereby, the dehumidifying efficiency is also improved.

In the air conditioner of the second aspect , the first indoor heat exchanger 21 is provided with the refrigerant flow paths which are parallel to each other and flows through the first indoor heat exchanger 21. Are provided so as to be larger than the cross-sectional area of the flow path.

That is, the first and second indoor heat exchangers 21 and 2
In the case where the cross-sectional areas of the respective flow paths 2 are different, for example, in a cross-fin tube type heat exchanger, it is possible to configure the heat transfer pipes through which the refrigerant flows with different pipe diameters. By making the number of parallel refrigerant flow paths, that is, the number of paths different, it is possible to use heat transfer tubes having the same diameter as the first and second indoor heat exchangers 21 and 22. Therefore,
In manufacturing the first and second indoor heat exchangers 21 and 22 in this case, if a header corresponding to a desired number of passes is attached to each of the refrigerant ports at the final stage of the assembly, the manufacturing and assembly up to that point is the first.・ Since the operations can be performed in the second indoor heat exchangers 21 and 22 similarly to each other, the production becomes easy.

[0023]

Next, a specific embodiment of the air conditioner of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a refrigerant circuit diagram of a separate type air conditioner configured by connecting an indoor unit 2 to an outdoor unit 1.
The outdoor unit 1 includes a compressor 3 therein.
The discharge pipe 4 and the suction pipe 6 in which the accumulators 5 are interposed are respectively connected to the primary port of the first four-way switching valve 7.

A first gas pipe 8 and a second gas pipe 9 are respectively connected to the secondary port of the first four-way switching valve 7, and the first gas pipe 8 is connected to a second four-way switching valve (connection port). State switching means) 1
0 is connected to one primary port. A first liquid pipe 11 is connected to the other primary port of the second four-way switching valve 10, and a check valve bridge circuit 12 and a second liquid pipe (described later) are sequentially connected to the first liquid pipe 11. 13. An outdoor heat exchanger 15 provided with an outdoor fan 14 is connected, and the second gas pipe 9 is connected to the outdoor heat exchanger 15.

A gas-side relay pipe 16 and a liquid-side relay pipe 17 are connected to the secondary port of the second four-way switching valve 10, and a gas-side connecting pipe 18 and a liquid-side relay pipe 16 are connected to these relay pipes 16. An indoor heat exchanger 20 provided inside the indoor unit 2 is connected via the communication pipe 19.

The indoor heat exchanger 20 is divided into a first indoor heat exchanger 21 connected to the gas communication pipe 18 and a second indoor heat exchanger 22 connected to the liquid communication pipe 19. The indoor heat exchangers 21 and 22 are connected to each other via an intermediate pipe 24 provided with an electric expansion valve (throttle means) 23 for dehumidification. Further, these indoor heat exchangers 21 and 22 are provided along the ventilation path of the indoor air sucked into the indoor unit 2 when the indoor fan 25 is operated.
The indoor heat exchanger 21 and the second indoor heat exchanger 22 are installed in the indoor unit 2 in this order.

As shown in FIG. 2, the second indoor heat exchanger 22 is provided with one system of refrigerant flow passages 2 on the liquid side communication pipe 19 side.
2a, and a path-taking shape including two parallel refrigerant distribution passages 22b and 22b on the intermediate pipe 24 side. On the other hand, the entire first indoor heat exchanger 21 is formed in a path-taking shape having three systems of refrigerant distribution passages 21a parallel to each other.

As shown in FIG. 1, the check valve bridge circuit 12 includes a first inlet / outlet port 12a to which the first liquid pipe 11 is connected, and a second inlet / outlet port 12b to which the second liquid pipe 13 is connected. , The inlet pipe 31 and the outlet pipe 32 are connected in parallel with each other, and the inlet pipe 31 is connected to the first and second check valves 33.
34, and a third / fourth check valve 35 in the outlet pipe 32.
・ 36 are provided respectively. The rectifying inlet port 12c between the first check valve 33 and the second check valve 34 in the inlet pipe 31 and the third check valve 35 and the fourth check valve 36 in the outlet pipe 32 are connected. A rectification pipe 37 is provided between the rectification outlet port 12d and the rectification outlet port 12d.

The first check valve 33 and the second check valve 34 are respectively connected to the first port 12a and the second port 12
The inlet pipes 31 are interposed in a direction allowing the refrigerant flow from the b side toward the rectification inlet port 12c. Also,
The third check valve 35 and the fourth check valve 36 are respectively connected to the outlet pipe 32 in directions allowing the refrigerant flow from the rectifying outlet port 12d toward the first inlet / outlet port 12a / second inlet / outlet port 12b. Has been established.

On the other hand, a supercooling heat exchanger 38 composed of a double pipe is connected to the rectification pipe 37 from the rectification inlet port 12c side.
And a first electric expansion valve 39 whose opening is controlled so as to function as a pressure reducing mechanism during a cooling / heating operation, which will be described later. And, between the rectification inlet port 12c and the outer pipe inlet port of the subcooling heat exchanger 38, the second electric expansion valve 40
Is provided, and a second injection pipe 42 that connects an outer pipe outlet port of the subcooling heat exchanger 38 to a suction port of the compressor 3 is provided.

As a result, the refrigerant flowing from the first liquid pipe 11 through the first check valve 33 or the refrigerant flowing from the second liquid pipe 13 through the second check valve 34 is supplied to the rectifying inlet port 12c and the first electric motor. A part of the first injection pipe 41 is partially provided according to the opening ratio between the expansion valve 39 and the second electric expansion valve 40.
Divert to When the divided refrigerant passes through the subcooling heat exchanger 38, it flows from the rectifying inlet port 12c through the subcooling heat exchanger 38.
The heat exchange occurs with the main refrigerant flowing to the rectification outlet port 12d through the inner pipe, and is then returned to the compressor 3 through the second injection pipe 42.

Further, the first liquid pipe 1 is connected to the refrigerant circuit.
A bypass pipe 43 is provided between the intake pipe 1 and the suction pipe 6,
A bypass opening / closing valve 44 composed of a one-way solenoid valve is interposed in the bypass pipe 43.

In the air conditioner having the above-described structure, the heating operation is performed by fully opening the electric expansion valve 23 for dehumidification, closing the bypass on-off valve 44, and setting the first four-way switching valve 7 and the second
The four-way switching valve 10 is located at a switching position indicated by a solid line in the figure, and the compressor 3 is driven in this state. At this time, if the second electric expansion valve 40 is also in the fully closed state, the refrigerant discharged from the compressor 3 will receive the first four-way switching valve 7, the first gas pipe 8,
After being supplied to the indoor unit 2 through the second four-way switching valve 10 and the gas-side relay pipe 16 and sequentially passing through the first indoor heat exchanger 21 and the second indoor heat exchanger 22, the liquid-side relay pipe 17 Outdoor heat via the two-way switching valve 10, the first liquid pipe 11, the first check valve 33, the supercooling heat exchanger 38, the first electric expansion valve 39, the fourth check valve 36, and the second liquid pipe 13. After flowing into the exchanger 15 and passing through the outdoor heat exchanger 15, it is returned to the compressor 3 via the second gas pipe 9 and the first four-way switching valve 7.

In such a heating cycle, the first
The second indoor heat exchangers 21 and 22 are a condenser and the outdoor heat exchanger 1
Each of 5 functions as an evaporator and discharges the amount of heat absorbed from the outside to the room to perform room heating. During this heating operation, the opening degree of the first electric expansion valve 39 is controlled so that the evaporated refrigerant returned to the compressor 3 through the outdoor heat exchanger 15 is maintained at a predetermined degree of superheat.

On the other hand, the cooling operation is performed by driving the compressor 3 by switching the first four-way switching valve 7 to the switching position shown by the broken line in the drawing. At this time, the compressor 3
As shown by the dashed arrow in the figure, the refrigerant discharged from the first heat exchanger 38, the first four-way switching valve 7, the outdoor heat exchanger 15, the second liquid pipe 13, the second check valve 34, the supercooling heat exchanger 38, 1 Electric expansion valve 39
It sequentially passes through the third check valve 35 and the first liquid pipe 11, and further,
After sequentially passing through the second indoor heat exchanger 22 and the first indoor heat exchanger 21 from the second four-way switching valve 10 and the liquid-side relay pipe 17, the gas-side relay pipe 16, the second four-way switching valve 10, and the second 1 gas pipe 8
It is returned to the compressor 3 via the first four-way switching valve 7.

In such a cooling cycle, the outdoor heat exchanger 15 is a condenser and the second and first indoor heat exchangers 22.2
Numerals 1 function as evaporators, and the amount of heat absorbed from the room is released to the outside to perform indoor cooling. During the cooling operation, the opening degree of the first electric expansion valve 39 is set so that the evaporated refrigerant passing through the first indoor heat exchanger 21 and returning to the compressor 3 is maintained at a predetermined degree of superheat. Controlled.

When the second electric expansion valve 40 is opened during the heating operation, for example, the first and second indoor heat exchangers 21 are opened.
The high-temperature and high-pressure liquid refrigerant condensed in 22 is the first liquid pipe 11.
When passing through the first check valve 33 and reaching the rectifying inlet port 12c, a part of the liquid refrigerant is subjected to the first injection according to the opening ratio between the first electric expansion valve 39 and the second electric expansion valve 40. The flow branches to the pipe 41. The branched liquid refrigerant is decompressed by the throttling action when passing through the second electric expansion valve 40, becomes a low-temperature low-pressure gas-liquid mixed refrigerant, and flows into the outer pipe of the supercooling heat exchanger 38.

On the other hand, the main refrigerant flowing from the rectifying inlet port 12c through the rectifying pipe 37 remains at a high temperature and a high pressure when flowing into the subcooling heat exchanger 38. Heat exchange occurs when passing through the vessel 38. Thereby, the divided refrigerant absorbs heat and is gasified, and is returned to the compressor 3 through the second injection pipe 42. In a state where the temperature of the main refrigerant decreases and the degree of supercooling increases, the main refrigerant becomes a low-temperature and low-pressure gas-liquid mixed refrigerant by a throttling action when passing through the first electric expansion valve 39. As the degree of supercooling is increased as described above, the overall refrigerant circulation amount is increased, thereby improving the heating capacity. Even during the operation in the cooling cycle, by opening the second electric expansion valve 40, an operation state in which the cooling capacity is further improved can be achieved by the same operation as described above.

Next, the dehumidifying operation in the heating cycle in which the first four-way switching valve 7 is located at the switching position shown by the solid line in the figure will be described. At this time, the second four-way switching valve 10 switches to the switching position indicated by the broken line in the figure. In addition, the first and second electric expansion valves 39 and 40 are fully closed, respectively, while the bypass on-off valve 44 is opened. Then, the opening of the dehumidifying electric expansion valve 23 is controlled so that it functions as a pressure reducing mechanism. Further, the outdoor fan 14 is set to the ultra low speed rotation state or the stop state.

In this operating state, the refrigerant discharged from the compressor 3 is supplied to the first four-way switching valve 7, the first gas pipe 8, the second four-way switching valve 10, and the liquid as indicated by the dashed line arrow in the figure. Side relay pipe 1
7 and flows into the second indoor heat exchanger 22. Then, after the heat is released and condensed when passing through the heat exchanger 22, the pressure is reduced by the electric expansion valve 23 for dehumidification. After that, the gas side relay pipe 16
The liquid flows into the first liquid pipe 11 from the four-way switching valve 10, and is returned from the first liquid pipe 11 to the compressor 3 via the bypass pipe 43 and the suction pipe 6.

Therefore, the indoor air sucked into the indoor unit 2 by the operation of the indoor fan 25 is first cooled when passing through the first indoor heat exchanger 21, and the moisture is condensed and dehumidified. Thereafter, the low-temperature indoor air is reheated when passing through the second indoor heat exchanger 22. As a result, air whose humidity has been reduced without changing the temperature is blown into the room, and a so-called reheat dry operation is performed.

Further, in the air conditioner, the dehumidifying operation in the cooling cycle in which the first four-way switching valve 7 is located at the switching position indicated by the broken line in the drawing can be appropriately selected and performed. At this time, the second four-way switching valve 10 is located at the switching position indicated by the solid line in the figure, the first electric expansion valve 39 is fully opened, and the second electric expansion valve 40 is fully closed. Further, the bypass on-off valve 44 is closed, and the opening of the dehumidifying electric expansion valve 23 is controlled so that it functions as a pressure reducing mechanism. Further, the outdoor fan 14 is set to the ultra low speed rotation state or the stop state.

In this operating state, the refrigerant discharged from the compressor 3 flows into the outdoor heat exchanger 15 through the first four-way switching valve 7 and the second gas pipe 9 as shown by a two-dot chain line arrow in the figure. I do.
At this time, by keeping the outdoor fan 14 at a very low speed or in a stopped state, the condensation when passing through the outdoor heat exchanger 15 is suppressed, and thereafter, the second indoor heat exchange is performed through the same path as in the cooling operation. Into the vessel 22. Then, it condenses when passing through the heat exchanger 22 and then evaporates when passing through the first indoor heat exchanger 21. Thereafter, the gas is returned to the compressor 3 via the gas side relay pipe 16, the second four-way switching valve 10, the first gas pipe 8, the first four-way switching valve 7, and the suction pipe 6.

Therefore, also in this case, the indoor fan 25
The indoor air sucked into the indoor unit 2 by the operation of
After being cooled when passing through the indoor heat exchanger 21, it is reheated when passing through the second indoor heat exchanger 22, and a reheating dry operation is performed.

As described above, in the air conditioner according to the present embodiment, the first indoor heat exchanger 21 is located on the upstream side and the second indoor heat exchanger is located on the downstream side along the direction of air flow in the indoor unit 2. By arranging 22, the reheating dry operation of once cooling, dehumidifying and then reheating the room air by switching the second four-way switching valve 10 is performed by both the cooling cycle and the heating cycle. be able to. Thereby, for example, by appropriately selecting the cooling cycle dehumidifying operation and the heating cycle dehumidifying operation according to environmental changes such as the outside air temperature, the reheating dry operation with good reheating capability and dehumidifying efficiency is more stably performed. Can be made.

Further, in the above description, even during the heating cycle dehumidifying operation, the high-temperature and high-pressure discharge refrigerant from the compressor 3 flows into the second indoor heat exchanger 22 through the liquid-side connecting pipe 19, and then the first indoor heat exchange. The low-temperature and low-pressure gas refrigerant evaporated in the unit 21 is sent to the outdoor unit 1 through the gas-side communication pipe 18. Therefore, even if pipes having different diameters are used as the liquid-side communication pipe 19 and the gas-side communication pipe 18 as before, the low-pressure gas refrigerant is sent to the outdoor unit 1 through the large-diameter gas-side communication pipe 18. Therefore, the low pressure loss in the communication pipe caused in the conventional heating cycle dehumidifying operation is reduced. As a result, an increase in the evaporation temperature is suppressed, and the dehumidifying efficiency is improved.

Further, in the above embodiment, as described with reference to FIG. 2, the first and second indoor heat exchangers 21 are provided.
The number of refrigerant flow paths in 22, that is, the number of passes, is 1 pass, 2 passes, and 3 sequentially from the connection side to the liquid side communication pipe 19.
By increasing the number of paths, the cross-sectional area of the flow path is gradually increased. Therefore, in the evaporation process in the heat exchangers 21 and 22 during the cooling operation, the cross-sectional area of the flow path gradually increases in accordance with the increasing tendency of the gas refrigerant in the liquid refrigerant. The pressure loss at the time of passage is also minimized. Further, during the heating operation, the cross-sectional area of the flow path gradually decreases in accordance with the change from the gas refrigerant to the liquid refrigerant, so that a decrease in the flow velocity of the liquid refrigerant is suppressed, and good heating performance is maintained.

Further, even in the heating cycle dehumidifying operation or the cooling cycle dehumidifying operation, the high-pressure gas refrigerant flows into the second indoor heat exchanger 22 and condenses, and then evaporates in the first indoor heat exchanger 21. As the gas refrigerant changes to a low-pressure gas refrigerant, the flow path cross-sectional area on the side of the first indoor heat exchanger 21 is particularly large, so that low-pressure loss at the time of passing through the heat exchanger 21 is suppressed, thereby also evaporating. The rise in temperature is suppressed, and the dehumidification efficiency can be improved.

The first and second indoor heat exchangers 21 and 22
Each consist of a cross-fin tube type heat exchanger,
In a configuration in which the numbers of these paths are made different from each other as described above to make the flow path cross-sectional areas different from each other, these heat exchangers 21 and 22 are used.
At the final stage of assembly, if headers corresponding to a desired number of passes are attached to the refrigerant inlet / outlet at the final stage of assembly, the process up to that point is performed by the first and second indoor heat exchangers 21 and 22 having the same diameter. Since the operations can be performed in the same manner using a heat tube, the production becomes easy.

Further, in the above embodiment, during the heating cycle dehumidifying operation, the first and second electric expansion valves 39 and 40 are operated.
Are completely closed, and the evaporated refrigerant after passing through the first indoor heat exchanger 21 is returned to the compressor 3 through the bypass pipe 43. Therefore, since the circulating refrigerant does not pass through the outdoor heat exchanger 15, it is possible to perform a reheat dry operation that is hardly affected by changes in the outside air temperature. In FIG. 3A,
A Mollier chart during such a heating cycle dehumidifying operation is shown. The dehumidifying operation can be performed with almost no energy loss, and in particular, the amount of heat released during the condensation process can be sufficiently secured as the amount of reheat of the indoor air. As the dry operation, a dehumidification operation that can adjust the room temperature can be performed.

In the above embodiment, the air conditioner further provided with the injection pipes 41 and 42 is exemplified. However, in the air conditioner having such a configuration, the bypass pipe 43 is not provided. It is also possible to return the evaporated refrigerant after passing through the first indoor heat exchanger 21 to the compressor 3 through the above-mentioned injection pipes 41 and 42.

That is, during the heating cycle dehumidifying operation, the first
While the electric expansion valve 39 is in the fully closed state, the second electric expansion valve 40 is in the fully open state, and the evaporated refrigerant after passing through the first indoor heat exchanger 21 is supplied to the first liquid pipe 11 and the first inverted pipe in FIG. Stop valve 3
3, the refrigerant is returned to the compressor 3 through the first and second injection pipes 41 and 42. A Mollier diagram at this time is shown in FIG. The broken line in the figure indicates that the liquid refrigerant remaining in the outdoor heat exchanger 15 at the beginning of the operation is supplied from the second liquid pipe 13 and the second check valve 34 to the first and second injection pipes 41 and 42. 3A shows a transient state in which the air is sucked into the compressor 3 through the pump. In the subsequent steady state, as shown by a solid line, FIG.
The reheat dry operation is continued in the same state as described above.

Although the specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be implemented with various modifications within the scope of the present invention. For example, in the above embodiment, during the heating cycle dehumidifying operation, the bypass pipe 43 is used to return the evaporated refrigerant from the indoor side to the compressor 3 without passing through the outdoor heat exchanger 15.
Alternatively, the configuration in which the first and second injection pipes 41 and 42 are provided has been described, but the refrigerant is returned to the compressor by passing through the outdoor heat exchanger 15 during the heating cycle dehumidifying operation without providing these pipes. The present invention can be applied to an air conditioner having a configuration.

In the above embodiment, the first indoor heat exchanger 2
Although the number of paths in the first indoor heat exchanger 22 and the number of paths in the second indoor heat exchanger 22 are different from each other, the cross-sectional area of the flow path is different. A pipe having a diameter larger than that of the heat pipe may be used for the first indoor heat exchanger 21.

In the above embodiment, the decompression mechanisms during the cooling / heating operation and the dehumidifying operation are respectively constituted by the electric expansion valves 39 and 23. Instead of these, for example, each decompression mechanism is constituted by a capillary tube having an open / close valve connected in parallel. Can also be configured.

[0057]

As described above, in the air conditioner according to the first aspect of the present invention, the connection state switching means for switching the connection state of the indoor heat exchanger to the first gas pipe and the first liquid pipe. In both the cooling cycle dehumidifying operation and the heating cycle dehumidifying operation, the first indoor heat exchanger can function as an evaporator and the second indoor heat exchanger can function as a condenser to perform a reheat dry operation. It has become. Thereby, by appropriately selecting the cooling cycle dehumidifying operation and the heating cycle dehumidifying operation according to the environmental change such as the outside air temperature, the reheating dry operation with good reheating capability and dehumidifying efficiency is more stably performed. Can be made.

Further, for example, even when the outdoor unit and the indoor unit are connected to each other using a communication pipe, the first indoor heat exchanger 21 is used in both the cooling cycle and the heating cycle during the dehumidifying operation. The evaporated low-pressure gas refrigerant can be sent to the outdoor unit through the gas-side communication pipe. Therefore, even if the liquid side communication pipe is smaller in diameter than the gas side communication pipe, the low pressure loss in the communication pipe that has occurred in the conventional heating cycle dehumidifying operation is reduced, and
Since the rise in the evaporation temperature is suppressed, the dehumidifying efficiency is improved.

In addition to the above, in the air conditioner according to the first aspect, the flow path cross-sectional area of the refrigerant in the first indoor heat exchanger which functions as an evaporator during the dehumidifying operation is determined by the flow of the second indoor heat exchanger. Since it is larger than the road cross-sectional area, the air conditioning capacity during the cooling / heating operation is improved, and the low pressure loss when passing through the first indoor heat exchanger during the dehumidifying operation is also suppressed, thereby improving the dehumidifying efficiency.

[0060] In the air conditioner according to the second aspect, the number of passes of each indoor heat exchanger is made different so that the flow path cross-sectional area of the first indoor heat exchanger is larger than that of the second indoor heat exchanger. In this case, when manufacturing the first and second indoor heat exchangers composed of the cross-fin tube type heat exchanger,
At the final stage of assembly, if headers corresponding to the desired number of passes are attached to the refrigerant inlet / outlet respectively, the production assembly up to that point is the first
Since the second indoor heat exchanger can perform the same operation using the same heat transfer tube, the production becomes easy.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the number of passes of each of a first indoor heat exchanger and a second indoor heat exchanger in the air conditioner.

FIG. 3 is a Mollier diagram during a dehumidifying operation, and FIG. 3A is a Mollier diagram during a heating cycle dehumidifying operation in which evaporated refrigerant is returned to a compressor through a bypass pipe in the air conditioner; FIG. 2B is a Mollier chart during a heating cycle dehumidifying operation in which the evaporated refrigerant is returned to the compressor through an injection pipe in the air conditioner, and FIG. 2C is a Mollier chart during a conventional cooling cycle dehumidifying operation. It is.

FIG. 4 is a refrigerant circuit diagram of a conventional air conditioner capable of a cooling cycle dehumidifying operation.

FIG. 5 is a refrigerant circuit diagram of a conventional air conditioner capable of performing a heating cycle dehumidifying operation.

[Explanation of symbols]

 Reference Signs List 3 compressor 7 first four-way switching valve 8 first gas pipe 9 second gas pipe 10 second four-way switching valve (connection state switching means) 11 first liquid pipe 13 second liquid pipe 15 outdoor heat exchanger 20 room Inside heat exchanger 21 First indoor heat exchanger 22 Second indoor heat exchanger 23 Electric expansion valve for dehumidification (throttle means) 39 First electric expansion valve (Decompression mechanism)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-34219 (JP, A) JP-A-3-107667 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 13/00 F25B 29/00

Claims (2)

(57) [Claims] A first gas pipe (8) is connected to a secondary port of a four-way switching valve (7) in which a discharge side and a suction side of a compressor (3) are respectively connected to a primary port. , Indoor heat exchanger (2
0), the first liquid pipe (11), the pressure reducing mechanism (39), the second liquid pipe (13), the outdoor heat exchanger (15), and the second gas pipe (9) are connected to form a refrigerant circulation circuit. The indoor heat exchanger (20) is connected to the first indoor heat exchanger (2) on the first gas pipe (8) side.
1) and the second indoor heat exchanger (22) on the first liquid pipe (11) side
And a throttle means (23) interposed as a dehumidifying depressurizing mechanism during the dehumidifying operation is provided between the first indoor heat exchanger (21) and the second indoor heat exchanger (22).
The refrigerant discharged from the compressor (3) is supplied to the first gas pipe (8), and the first and second indoor heat exchangers (21) and (22) function as condensers, and the outdoor heat exchanger (15) functions as an evaporator. While performing the heating operation, the refrigerant discharged from the compressor (3) is supplied to the second gas pipe (9).
An air conditioner that performs cooling operation by supplying the outdoor heat exchanger (15) as a condenser and the first and second indoor heat exchangers (21) and (22) as evaporators. Tube (8)
During the cooling cycle dehumidification operation in which the refrigerant discharged from the compressor (3) is supplied to the second gas pipe (9) between the first liquid pipe (11) and the first liquid pipe (11), the first liquid pipe (11) is connected to the second liquid pipe (11). Indoor heat exchanger (2
2) The first indoor heat exchanger (21) is connected to the first gas pipe (8).
During the heating cycle dehumidifying operation performed by supplying the refrigerant discharged from the compressor (3) to the first gas pipe (8) while maintaining the connection state at the time of the cooling / heating operation respectively connected to the first gas pipe (8). ) in the second indoor heat exchanger (22), the first indoor heat exchanger (21) is a connection state switching means for switching each connected connection state (10) provided in the first liquid pipe (11), further
The flow path cross-sectional area of the refrigerant in the first indoor heat exchanger (21)
Make it larger than the flow path cross-sectional area of the second indoor heat exchanger (22).
Air conditioner, characterized by that. 2. A refrigerant flow path, which is parallel to the first indoor heat exchanger (21) and flows through the refrigerant in a divided manner, has a total cross-sectional area of the flow path of the second indoor heat exchanger (22). The air conditioner according to claim 1 , wherein a plurality of the air conditioners are provided so as to be larger than a cross-sectional area.