JP2003176943A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner comprising an indoor heat exchanger having two or more refrigerant channels, and capable of preventing the dew condensation on a cooling air blow-out channel in the cooling operation or dehumidifying operation. <P>SOLUTION: In the air conditioner comprising a compressor 1, an outdoor heat exchanger 3, an expansion valve 4 and the indoor heat exchanger 6 successively connected through the piping, the indoor heat exchanger 6 has two or more refrigerant channels 6a, 6b, the refrigerant channels 6a, 6b are respectively provided with temperature sensors 13, 14, and a controller 12 is mounted for controlling the cooling operation to prevent the dew condensation in the cooling air blow-out channel 20 on the basis of output signals of the temperature sensors 13, 14. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly, it is effective to prevent dew condensation in a cold air blowing path in a structure including an indoor heat exchanger having a plurality of refrigerant flow paths. The present invention relates to an air conditioner that can be prevented.

[0002]

2. Description of the Related Art In a conventional air conditioner, as shown in FIG. 6, a compressor 1 and an outdoor heat exchanger 3 arranged outdoors.
And the electric expansion valve 4 are connected in this order by the refrigerant pipes, and the electric heat expansion valve 4 is connected via the liquid side two-way valve 5 to the indoor heat exchanger 6 which is arranged indoors. To the outdoor compressor 1 via the gas side three-way valve 7 to form a refrigeration cycle.

The compressor 1 is connected to a refrigerating cycle via a four-way valve 2, and by switching the four-way valve 2, either the outdoor heat exchanger 3 side or the indoor heat exchanger 6 side is directed. Also, the compressed refrigerant can be delivered.

In the above structure, during cooling, the refrigerant compressed by the compressor 1 is condensed by the outdoor heat exchanger 3, decompressed by the electric expansion valve 4 and evaporated by the indoor heat exchanger 6 to cool the indoor air. After that, the cycle is returned to the compressor 1. In such a refrigeration cycle, piping on the inlet side and outlet side of the indoor heat exchanger 6, that is, piping between the compressor 1 and the indoor heat exchanger 6, and piping between the expansion valve 4 and the indoor heat exchanger 6. Are provided with temperature sensors 8 and 9, respectively.

The control device 12 receives the detection signals from the temperature sensors 8 and 9 to calculate the temperature difference between the temperature sensors 8 and 9 and controls the opening of the expansion valve 4 so that the temperature difference becomes constant. The evaporation of the refrigerant in the heat exchanger was properly maintained to ensure the cooling capacity.

By the way, in recent years, in order to improve the operation efficiency of an air conditioner, an indoor heat exchanger 6 having a plurality of refrigerant flow paths has been used. FIG. 7 is a schematic diagram of an air conditioner when the indoor heat exchanger 6 including the two refrigerant flow paths 6a and 6b is used. Refrigerant flow path 6a,
6b are respectively connected in parallel on the inlet side and the outlet side of the indoor heat exchanger 6.

FIG. 8 is a sectional view of an indoor unit in which the indoor heat exchanger is housed. The indoor unit has suction ports 17, 1 on the top and front of the main body in order to suck as much indoor air as possible.
8 is formed. The refrigerant flow paths 6a and 6b are three-dimensionally arranged in order to efficiently exchange heat with the indoor air taken in through the suction ports 17 and 18. Ie 2
The two refrigerant flow paths 6a and 6b are arranged in upper and lower two stages,
In addition, the upper and lower refrigerant channels 6a and 6b are formed to have different channel lengths due to the installation space.

In the air conditioner having the above structure, since the refrigerant flows in parallel in the upper refrigerant passage 6a and the lower refrigerant passage 6b, the pressure loss of the evaporation pressure of the refrigerant is reduced and the cooling is efficiently performed. You can drive.

[0009]

As shown in FIG. 7, in the air conditioner provided with the indoor heat exchanger having a plurality of refrigerant flow paths, the inlet side of the indoor heat exchanger 6 obtained by the temperature sensors 8 and 9. When the difference between the temperature and the outlet side temperature is controlled to be constant, the lengths of the refrigerant flow paths 6a and 6b are different from the viewpoint of design as described above, and the refrigerant flow paths 6a and 6b are arranged in upper and lower two stages. Differences in the flow rates of the refrigerant flowing through the refrigerant passages are likely to occur, which may cause a temperature difference between the refrigerant passages 6a and 6b.

When the temperature difference between the refrigerant flow paths 6a and 6b becomes large, the indoor air introduced into the low temperature side refrigerant flow path is sufficiently cooled and dehumidified while passing through the refrigerant flow path, and the indoor heat exchange is performed as cooling air. On the other hand, the indoor air passing through the high temperature side refrigerant flow path is sent out from the indoor heat exchanger 6 as uncooled air in a humid state without being cooled while being sent out from the air conditioner 6.

As shown in FIG. 8, the cooling air and the uncooled air sent from the indoor heat exchanger 6 join together in the air blowing path 20 from the indoor heat exchanger to the air blowing port 19, whereby the uncooled air The cooling air is cooled to cause dew condensation, and the exposed surface in the cold air blowing path, that is, the wall surface of the path, the indoor fan 1
1 or the surface of the louver 21 was exposed to dew, and finally water was scattered in the room.

In view of the above, the present invention provides an air conditioner having an indoor heat exchanger having a plurality of refrigerant flow paths and capable of preventing dew condensation on a cold air blowing path during a cooling operation or a dehumidifying operation. The purpose is.

[0013]

In order to achieve the above object, an air conditioner according to the present invention comprises a compressor, an outdoor heat exchanger, an expansion valve and an indoor heat exchanger, which are sequentially connected via piping. A refrigeration cycle is provided, and the indoor heat exchanger has a plurality of refrigerant channels connected in parallel and a temperature sensor that detects the temperature of each refrigerant channel, and the temperature difference of each refrigerant channel during the cooling operation. It is characterized in that a control device for controlling the cooling operation is provided in a decreasing direction.

That is, when an indoor heat exchanger having a plurality of refrigerant flow paths is used, the refrigerant flows in parallel in each refrigerant flow path during the cooling operation, and as described above, each refrigerant flow path. As a result, a temperature difference occurs, and as a result, dew condensation may occur in the cold air blowing path.

Therefore, in the present invention, a temperature sensor is provided in each refrigerant flow passage, and a control device for controlling the cooling operation in the direction of reducing the temperature difference between the refrigerant flow passages is provided, so that the dew in the air blowing path is provided. The sticking is effectively prevented.

As the control device, a control microcomputer is used to calculate the temperature difference between the temperatures of the respective refrigerant channels detected by the temperature sensor, and the cooling operation is controlled so that the temperature difference is reduced. Good. By reducing the temperature difference in the refrigerant flow paths, the temperature of the air after passing through each refrigerant flow path becomes approximately the same, and it is possible to prevent dew condensation and dew condensation in the cold air blowing path. Note that the cooling operation also includes a dehumidifying operation that is operated in the same cooling operation cycle.

In order to control the cooling operation so that the temperature difference in the refrigerant flow path becomes smaller, the control device may be provided with a capacity increasing means for increasing the cooling capacity as the temperature difference becomes larger. As the capacity increasing means, specifically, control is performed such that the opening of the expansion valve is opened as the temperature difference between the refrigerant passages is increased, or the rotation speed of the outdoor fan motor is increased as the temperature difference between the refrigerant passages is increased. It is possible to use such a control so that the operating frequency of the compressor is increased and the flow rate of the refrigerant is increased as the temperature difference between the refrigerant passages increases.

By providing the above capacity increasing means, sufficient refrigerant can be supplied also to the high temperature side refrigerant flow path, and it becomes possible to approach the temperature of the low temperature side refrigerant. Each of the exemplified capacity enhancing means may be used alone, or a plurality of them may be used in combination.

In addition to increasing the cooling capacity, it is also possible to provide capacity suppressing means for suppressing the cooling capacity in the indoor heat exchanger. By suppressing the evaporation of the refrigerant, the temperature of the refrigerant passage on the low temperature side approaches the temperature of the refrigerant passage on the high temperature side, and the temperature difference can be reduced.

As the capacity suppressing means, for example, a flow rate adjusting valve for adjusting the flow rate of the refrigerant is provided in the refrigerant channel, and the flow rate adjusting valve provided in the refrigerant channel on the lower temperature side is closed as the temperature difference between the refrigerant channels becomes larger. It is possible to increase the number of parts by adopting a configuration in which the rotation speed of the indoor fan motor is controlled to decrease as the temperature difference of the refrigerant flow path increases It is possible to reduce the temperature difference in the refrigerant flow path without the need. These methods may be used alone or in combination.

As means for reducing the temperature difference in the refrigerant flow passage, either capacity enhancing means or capacity suppressing means may be used, but both means are provided, and either of them is provided depending on the operating conditions. If one is selected, a more comfortable cooling operation can be performed.

That is, when the room temperature is still higher than the set temperature, the capacity increasing means is used to reduce the temperature difference between the refrigerant passages while increasing the cooling capacity, and when the temperature difference between the two is small. Reduces the temperature difference of the refrigerant flow path while suppressing the cooling capacity by using the capacity suppressing means, thereby effectively preventing the dew condensation while maintaining comfort without causing excess or deficiency of the cooling capacity. be able to.

The air conditioner according to the present invention may be a separate type comprising an indoor unit and an outdoor unit, or a condenser and an evaporator are integrally housed in the main body like a type mounted on a window frame. It may be an integrated type.

The cooling operation may be carried out only, or the cooling operation may be performed by providing the refrigeration cycle with a switching valve such as a four-way valve for switching the refrigeration cycle to either the cooling operation cycle or the heating operation cycle. It may be one that enables both the heating operation and the heating operation.

In any case, according to the present invention, in the main body containing the evaporator during the cooling operation,
It is possible to effectively prevent condensation and dew condensation in the cold air blowing path from the evaporator to the cold air blowing outlet.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIGS. 1 and 2
FIG. 1 is a diagram showing a first embodiment of the present invention. In the present embodiment, when the temperature difference between the refrigerant passages becomes large, the cooling capacity is increased as a means for reducing the temperature difference between the refrigerant passages. It is characterized by the provision of capacity-enhancing means,
Specifically, as the capacity increasing means, a configuration is adopted in which the expansion valve is controlled to open as the temperature difference between the refrigerant passages increases.

FIG. 1 is a refrigerant circuit diagram showing the refrigerant flow in the air conditioner during cooling, and FIG. 2 is a schematic sectional view of the indoor unit. The basic configuration of the air conditioner in this embodiment is the same as that of the conventional air conditioner shown in FIGS. 7 and 8.

That is, the air conditioner in this embodiment is a separate type consisting of an outdoor unit and an indoor unit, and the compressor 1, the outdoor heat exchanger 3 and the electric expansion valve 4 housed in the outdoor unit are arranged in this order. The indoor heat exchanger 6 accommodated in the indoor unit is connected by piping through the refrigerant pipe, the electric expansion valve 4 and the liquid side two-way valve 5, and the indoor heat exchanger 6 and the gas side three-way valve 7 are connected. A refrigerating cycle is constructed by connecting again to the outdoor compressor 1 via a pipe, and the outdoor heat exchanger 3 and the indoor heat exchanger 6 are used as a condenser or an evaporator.

The compressor 1 is connected to the refrigeration cycle via a four-way valve 2 which is a switching valve, and by switching the four-way valve 2, either the outdoor heat exchanger 3 side or the indoor heat exchanger 6 side is connected. The compressed refrigerant can be delivered in either direction.

The indoor heat exchanger 6 has two refrigerant flow paths 6a,
6b, and as in FIG. 7, the refrigerant flow paths 6a, 6b.
Are arranged in upper and lower two stages in the indoor heat exchanger 6, and are connected in parallel on the inlet side and the outlet side of the indoor heat exchanger 6, respectively. As shown in FIG. 1, the air conditioner is configured such that the refrigerant flows in parallel in the refrigerant channels 6a and 6b. In the figure, the direction of the arrow indicates the direction in which the refrigerant flows.

Temperature sensors 13 and 14 are provided near the respective intermediate portions of the refrigerant flow paths 6a and 6b of the indoor heat exchanger 6, and the temperature sensor 8 is provided in the refrigerant inlet side pipe of the compressor 1.
Is provided. The detection signals of these temperature sensors 8, 13, 14 are input to the control device 12. In the control device 12, first, the temperature difference between the temperature sensors 13 and 14 is calculated, and the opening degree of the expansion valve 4 as the capacity increasing means is controlled so as to eliminate the temperature difference.

At this time, as a method of controlling the opening degree of the expansion valve 4, when the temperature difference is small, a setting operation in which the opening degree is previously determined according to the room temperature, the input temperature, etc., is executed so that the temperature difference exceeds a certain temperature. It is possible to employ a method of opening the opening degree to a certain degree when the temperature difference becomes small and returning to the original opening degree when the temperature difference becomes small, or a method of proportionally adjusting the opening degree according to the temperature difference.

For example, when the temperature difference between the temperature sensors 13 and 14 is measured to be equal to or higher than the reference, it is considered that the refrigerant in the refrigerant channel having the higher temperature has a large gas phase ratio.
Therefore, the control device 12 opens the expansion valve 4 and causes more refrigerant to flow into the indoor heat exchanger 6, thereby increasing the ratio of the liquid phase in the refrigerant flow path to the ratio of the gas phase, and the temperature sensor 13, The temperature difference of 14 is reduced.

As a result, the indoor air passing through either of the refrigerant flow paths 6a and 6b in the indoor heat exchanger 6 is sufficiently cooled,
It can be dehumidified and is in the cold air blowing path 20 to the cold air blowing port 19 on the downstream side of the indoor heat exchanger 6, that is, the wall surface of the path, the indoor fan 11, or the louver 2.
It is possible to prevent dew on the surface of No. 1.

When the cooling capacity is increased by the capacity increasing means, a so-called liquid back phenomenon may occur in which the refrigerant in the indoor heat exchanger 6 does not completely evaporate and flows to the compressor 1 side in a liquid state. Therefore, in the present embodiment, a temperature sensor 8 that detects the temperature of the refrigerant suction side pipe of the compressor 1 is provided, and the detection signal is input to the control device 12,
The controller 12 calculates the temperature difference between the temperature sensors 13 and 14 and the temperature sensor 8, and controls the capacity increasing means so that the temperature difference becomes constant, thereby preventing the occurrence of the liquid back phenomenon. It is configured to prevent.

[Second Embodiment] FIG. 3 is a refrigerant circuit diagram showing a refrigerant flow in an air conditioner according to a second embodiment of the present invention. In the present embodiment, the temperature sensors 13, 1
When the temperature difference of 4 is measured to be equal to or higher than the reference, the motor increasing speed of the outdoor fan 10 is controlled instead of controlling the opening degree of the expansion valve 4 as the capacity increasing means.
Other configurations are similar to those of the first embodiment.

For example, when the temperature difference between the temperature sensors 13 and 14 is measured to be equal to or higher than the reference, it is considered that the refrigerant in the refrigerant passage having the higher temperature has a large gas phase ratio as described above. To be Therefore, the control device 12 increases the outdoor fan motor rotation speed, radiates more heat in the outdoor heat exchanger 3, and lowers the temperature of the refrigerant introduced into the refrigerant flow passages 6a and 6b, whereby the temperature sensor 13, It is possible to reduce the temperature difference of 14 and sufficiently cool and dehumidify the indoor air in the indoor heat exchanger 6.

[Third Embodiment] FIG. 4 shows a third embodiment of the present invention.
FIG. 3 is a refrigerant circuit diagram showing the flow of refrigerant of the air conditioner showing the embodiment of FIG. In this embodiment, the temperature sensor 13,
When the temperature difference of 14 is measured to be equal to or higher than the reference, the operating frequency of the compressor 1 is controlled as the capacity increasing means, and the other configurations are the same as those of the first embodiment. .

For example, when the temperature difference between the temperature sensors 13 and 14 is measured to be equal to or higher than the reference, the operating frequency of the compressor 1 is increased and the flow rate of the refrigerant in the refrigerant passage is increased. as a result,
The indoor heat exchanger 6 can sufficiently secure the refrigerant necessary for heat exchange, and the entire interior heat exchanger 6 has the refrigerant flow path 6
The proportion of the liquid phase in a and 6b increases with respect to the proportion of the gas phase,
The temperature difference between the respective coolant channels can be reduced. Therefore, the indoor heat exchanger 6 can sufficiently cool and dehumidify the indoor air.

[Fourth Embodiment] FIG. 5 shows a fourth embodiment of the present invention.
FIG. 3 is a refrigerant circuit diagram showing the flow of refrigerant of the air conditioner showing the embodiment of FIG. In this embodiment, the temperature sensor 13,
When the temperature difference of 14 is measured to be equal to or more than the reference, as a means for reducing the temperature difference of each refrigerant flow path, a capacity suppressing means for suppressing the cooling capacity in the refrigerant flow path is provided. The other configurations are similar to those of the first embodiment.

In the present embodiment, as the capacity suppressing means, a configuration is adopted in which the rotational speed of the motor of the indoor fan 11 is controlled to decrease as the temperature difference between the refrigerant passages increases. In addition, as another capability suppressing means, each refrigerant flow path 6
Provided with a flow rate adjusting valve for adjusting the flow rate of the refrigerant in a and 6b,
As the temperature difference between the refrigerant flow paths 6a and 6b increases, a control may be employed to close the flow rate adjusting valve provided in the refrigerant flow path on the low temperature side to reduce the refrigerant flow rate.

Explaining the control method of the capacity suppressing means, for example, when the temperature difference between the temperature sensors 13 and 14 is measured to be a reference value or more, the motor rotation speed of the indoor fan 11 is lowered and the indoor heat exchanger 6 cools. Reduce the amount of air that is taken.
As a result, the refrigerant necessary for heat exchange can be sufficiently secured in the indoor heat exchanger 6, and the indoor heat exchanger 6 as a whole is
The proportion of the liquid phase in the refrigerant channel increases with respect to the proportion of the gas phase,
The temperature difference between the coolant channels 6a and 6b can be reduced. That is, the indoor heat exchanger 6 can sufficiently cool and dehumidify the indoor air.

[0043]

As is apparent from the above description, according to the present invention, a temperature sensor is provided in each refrigerant flow passage of an evaporator having a plurality of refrigerant flow passages, and a temperature difference between the refrigerant flow passages during cooling operation is provided. Since the control device for controlling the cooling operation is provided in the decreasing direction, it is possible to prevent dew condensation in the cold air blowing path.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner showing a first embodiment.

FIG. 2 is a schematic cross-sectional view showing the indoor unit of the first embodiment.

FIG. 3 is a refrigerant circuit diagram of an air conditioner showing a second embodiment.

FIG. 4 is a refrigerant circuit diagram of an air conditioner showing a third embodiment.

FIG. 5 is a refrigerant circuit diagram of an air conditioner showing a fourth embodiment.

FIG. 6 is a schematic configuration diagram of a conventional air conditioner.

FIG. 7 is a schematic configuration diagram showing another form of a conventional air conditioner.

FIG. 8 is a sectional view of the indoor unit in FIG.

[Explanation of symbols]

1 compressor 2 four-way valve 3 outdoor heat exchanger 4 expansion valve 6 Indoor heat exchanger 8 Temperature sensor 11 Indoor fan 12 Control device 13, 14 Temperature sensor 17,18 Suction port 19 Cold air outlet 20 Cold wind blowing route 21 Louver

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Claims (7)

[Claims] 1. A refrigeration cycle in which a compressor, an outdoor heat exchanger, an expansion valve and an indoor heat exchanger are sequentially connected via piping, wherein the indoor heat exchanger has a plurality of refrigerant streams connected in parallel. And a temperature sensor that detects the temperature of each refrigerant flow path, and a control device that controls the cooling operation in a direction that reduces the temperature difference of each refrigerant flow path during the cooling operation is provided. Air conditioner. 2. The air conditioner according to claim 1, wherein the control device is provided with capacity enhancing means for enhancing a cooling capacity on a refrigerant inlet side of the indoor heat exchanger. 3. The air conditioner according to claim 2, wherein the capacity increasing means controls the expansion valve to open as the temperature difference between the refrigerant flow paths increases. 4. The capacity increasing means controls to increase the rotational speed of a drive motor of a fan that blows air to the outdoor heat exchanger, as the temperature difference of the refrigerant flow path increases. Air conditioner described. 5. The air conditioner according to claim 2, wherein the capacity increasing means controls to increase the operating frequency of the compressor as the temperature difference in the refrigerant flow path increases. 6. The control device comprises a capacity suppressing means for suppressing a cooling capacity in the indoor heat exchanger.
Air conditioner described. 7. The capacity suppressing means controls so that the rotational speed of a drive motor of a fan that blows air to the indoor heat exchanger decreases as the temperature difference of the refrigerant flow path increases. Air conditioner described.