JP2013002749A - Air conditioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an air conditioning device allowing dehumidification while supplying a sufficient air flow even when the cooling load is small.SOLUTION: The air conditioning device includes a compressor 1, an outdoor heat exchanger 3, electric expansion valves 4-6, and an indoor heat exchanger 8 which are sequentially connected by a refrigerant pipe 20 to form a refrigeration cycle. The indoor heat exchanger 8 includes a plurality of heat exchangers 8a, 8b, and these heat exchangers are connected to distribution flow paths 21, 22 diverging in parallel from the refrigerant pipe. The respective distribution flow paths are provided with the electric expansion valves 5, 6. The air conditioning device also includes a suction air temperature sensor 14 for detecting temperature of air flowing into the indoor heat exchanger, a discharge pressure sensor 11 for detecting discharge pressure of the compressor, and a suction pressure sensor 10 for detecting suction pressure. In addition, the air conditioning device includes a control means 13 for closing an electric expansion valve corresponding to any of the plurality of heat exchangers when a difference between the temperature detected by the suction air temperature sensor and set temperature is smaller than a predetermined value and when dehumidifying operation is performed during low-load operation.

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner for equipment that requires a large amount of air even at a low load in order to air-condition a wide area.

  As a conventional air conditioner for equipment, there is one described in, for example, Japanese Patent Laid-Open No. 7-332736 (Patent Document 1). The thing of this patent document 1 describes the air conditioning apparatus which can dehumidify, supplying the sufficient quantity of cold air more than required humidity to a computer. More specifically, when the detected humidity is higher than a predetermined value, the opening degree of the electric expansion valve that does not close is closed corresponding to the divided indoor heat exchanger, and a part of the arranged electric expansion valve is closed. An air conditioner is described in which the amount of opening is increased corresponding to the total refrigerant flow rate.

JP 7-332736 A

  Patent Document 1 discloses an air conditioner that can be dehumidified while supplying a sufficient amount of cold air that is above the required humidity. However, in Patent Document 1, when the detected humidity is higher than a predetermined value, dehumidification is performed by closing a part of the expansion valve corresponding to the divided indoor heat exchanger. If it is low, dehumidification cannot be performed.

  In other words, in an air conditioning apparatus for cooling a computer, it is desirable that the air is not dehumidified even when the room air is cooled because the computer is damaged by static air or the like because it is damaged by static electricity. For this reason, in the thing of patent document 1, it dehumidifies especially when it becomes high humidity.

  However, in this Patent Document 1, since the dehumidifying operation is possible only at the time of a high load where the room temperature is high and the humidity is high, there is no consideration for dehumidifying at a low load, and the dehumidifying operation is performed. I can't do it. On the other hand, in the thing of patent document 1, in order to prevent the failure | damage of static electricity at the time of low load, it is comprised so that it may not dehumidify.

  An object of the present invention is to obtain an air conditioner that enables dehumidification while supplying a sufficient air volume even when the cooling load is small.

  To achieve the above object, the present invention provides an air conditioner configured to form a refrigeration cycle by sequentially connecting a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger through refrigerant piping. The indoor heat exchanger is composed of a plurality of divided heat exchangers, and the plurality of heat exchangers are connected to the distribution flow paths in which the refrigerant pipes are branched in parallel, Is provided with an electric expansion valve, and further includes a suction air temperature sensor for detecting the temperature of air flowing into the indoor heat exchanger, a discharge pressure sensor for detecting the discharge pressure of the compressor, and a suction pressure of the compressor When the dehumidifying operation is performed when the difference between the temperature detected by the suction air temperature sensor and the temperature set by the suction air temperature sensor is smaller than a predetermined value and the low load operation is performed, of the plurality of heat exchangers And a controlling means for controlling so as to close said electric expansion valve provided in the connected distribution channel to or Re.

  According to the present invention, it is possible to obtain an air conditioner that enables dehumidification while supplying a sufficient air volume even when the cooling load is small.

The refrigeration cycle system diagram which shows Example 1 of the air conditioning apparatus of this invention. The diagram explaining the expansion valve opening degree control in the air conditioning apparatus shown in FIG. 1, and the state of each part. The characteristic view which shows the relationship between the expansion valve opening degree and refrigerant | coolant flow volume in the air conditioning apparatus shown in FIG. The refrigeration cycle system diagram which shows Example 2 of the air conditioning apparatus of this invention. The diagram explaining the expansion valve opening degree control in the air conditioning apparatus shown in FIG. 4, and the state of each part. The characteristic view which shows the relationship between the expansion valve opening degree and refrigerant | coolant flow volume in the air conditioning apparatus shown in FIG.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

A first embodiment of an air conditioner according to the present invention will be described with reference to FIGS.
FIG. 1 is a refrigeration cycle diagram of an air conditioner, FIG. 2 is a diagram for explaining expansion valve opening control and the pressure state of the refrigeration cycle, and FIG. 3 is a characteristic diagram showing the relationship between the expansion valve opening and the refrigerant flow rate. It is.

As shown in FIG. 1, the air conditioner of the present embodiment includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3 that becomes a condenser during cooling, and an electric expansion valve (hereinafter simply referred to as expansion). 4, 5, 6, and main components such as an indoor heat exchanger 8 that serves as an evaporator and an accumulator 9 are sequentially connected by a refrigerant pipe 20 to form a refrigeration cycle. Further, a suction pressure sensor 10 for detecting the suction side pressure of the compressor 1, a discharge pressure sensor 11 for detecting the discharge side pressure, a discharge temperature thermistor 12 for detecting the discharge side refrigerant temperature, and the like are provided. Further, the expansion valve opening is output to the electric expansion valves 4, 5, 6, the pressure detection signal from the pressure sensors 10, 11, the refrigerant discharge gas temperature signal from the discharge temperature thermistor 12, the compressor A controller (control means) 13 constituted by a microcomputer or the like that receives a compressor rotation speed signal from one rotation speed detection means and controls the air conditioner is also provided.
In addition, when it is set as the air conditioning apparatus only for cooling operation, the said four-way valve 2 does not need to be provided.

  During the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 condenses in the outdoor heat exchanger 3 to become a high-temperature and high-pressure liquid refrigerant, is depressurized by the electric expansion valves 5 and 6, and the indoor heat exchanger 8. The refrigeration cycle is formed by evaporating into a low-temperature and low-pressure gas refrigerant and returning to the compressor 1 through the accumulator 9. A predetermined amount of air is sucked into the indoor heat exchanger 8, and when the refrigerant flowing through the indoor heat exchanger 8 evaporates, it is cooled by exchanging heat with the refrigerant, and the cooled air is cooled. It is blown into the room for use.

  In the present embodiment, the indoor heat exchanger 8 is divided into two parts with different capacities, and is composed of a small capacity heat exchanger 8a and a large capacity heat exchanger 8b, and the small capacity heat exchanger 8a. The electric expansion valve 5 is provided in the refrigerant pipe connected to 8a, and the electric expansion valve 6 is provided in the refrigerant pipe connected to the large-capacity heat exchanger 8b.

  Furthermore, an intake air temperature sensor 14 for detecting the intake air temperature to the indoor heat exchanger 8 and a blown air temperature sensor 15 for detecting the temperature of the blown air from the indoor heat exchanger 8 are provided, These air temperature sensors 14 and 15 are connected to the controller 13.

  In such an air conditioner, data from the intake air temperature sensor 14 and the blown air temperature sensor 15 is taken into the controller 13 to detect the cooling load. Usually, the controller 13 drives the compressor 1 at the operating frequency determined by the cooling load, and the refrigerant temperature Td detected by the discharge temperature thermistor 12 and the refrigerant detected by the discharge pressure sensor 11. The electric expansion valves 5, 6 are set so that the refrigerant discharge side superheat degree TdSH, which is a difference from the condensation temperature Tc calculated from the discharge pressure Pd, becomes a predetermined value set in advance to form an appropriate refrigeration cycle. The air conditioner is adjusted to perform cooling operation or the like.

  As described above, in the normal cooling operation state in which the refrigerant discharge side superheat degree TdSH is controlled to be a predetermined value, the intake air temperature T1 detected by the intake air temperature sensor 14 as shown in FIG. The suction pressure Ps and the discharge pressure Pd detected by the suction pressure sensor 10 and the discharge pressure sensor 11 are smaller than the predetermined value preset in the controller 13. Or the compressor rotational speed W from the rotational speed detection means is lower than a predetermined value preset in the controller 13, it is difficult to dehumidify with a conventional air conditioner for equipment, etc. Become.

  That is, in an air conditioner for equipment, etc., in order to spread the conditioned air over a wide air-conditioning target area, it is required to constantly blow out a large amount of air from the indoor heat exchanger 8 or always a predetermined amount of air or more. This is because it becomes difficult to cool the air to a sufficiently low temperature necessary for dehumidification in the indoor heat exchanger 8 when the refrigerant circulation amount is reduced due to the low load operation.

  In this embodiment, a function of dehumidification promotion operation (function of operating a refrigeration cycle so as to promote dehumidification) that enables dehumidification even during such low load operation is provided. When a dehumidifying operation is required at the time of load, it can be switched to the dehumidifying promotion operation.

  That is, in the air conditioner of the present embodiment, the indoor heat exchanger 8 is divided into two parts of a small capacity heat exchanger 8a and a large capacity heat exchanger 8b. The plurality of heat exchangers 8a and 8b are connected to distribution flow paths 21 and 22 in which the refrigerant pipe 20 is branched in parallel, and each distribution flow path 21 and 22 has a pressure reducing device. The electric expansion valves 5 and 6 are provided.

  When performing the dehumidification promotion operation, for example, the expansion valve opening Va is fully closed from the controller 13 to the electric expansion valve 5 corresponding to the small-capacity side heat exchanger 8a of the divided indoor heat exchanger 8. The heat exchanger 8a corresponding to the expansion valve 5 is closed. By this operation, the heat exchanging capacity in the indoor heat exchanger 8 is lowered and the suction pressure Ps is lowered, so that dew condensation is promoted in the heat exchanger 8b in which the refrigerant flows and passes through the heat exchanger 8b. Can promote dehumidification from the air.

  Instead of closing the electric expansion valve 5 corresponding to the small capacity side heat exchanger 8a, the electric expansion valve 6 corresponding to the large capacity side heat exchanger 8b may be closed. If the corresponding heat exchanger 8b is closed, the heat exchanging capacity in the indoor heat exchanger 8 can be further reduced and the refrigerant suction pressure Ps can be further reduced, so the load becomes very small and the refrigerant circulation rate is reduced. Even in a case where the temperature further decreases, dew condensation can be promoted in the heat exchanger 8a in which the refrigerant is circulating. Therefore, according to the present embodiment, it is possible to promote dehumidification with the heat exchanger 8a on the small capacity side even when the load becomes very small.

  As described above, according to the present embodiment, the indoor heat exchanger 8 is composed of a plurality of heat exchangers 8a and 8b having different capacities, and the electric expansion valves 5 and 6 are controlled according to the state of the load. As a result of supplying a sufficient air volume over a wide range from the state in which the load is slightly reduced to the state in which the load is significantly reduced, that is, the state in which the compressor rotational speed is greatly reduced, as well as during normal operation. An air conditioner that enables dehumidification can be obtained.

The control for switching to the dehumidification promoting operation described above at low load may be performed as follows, for example.
That is, in the state where the dehumidifying operation is required, when the difference between the temperature T1 detected by the intake air temperature sensor 14 and the set temperature T2 is smaller than a predetermined value set in advance and is in a low load state, A command is sent from the controller 13 to the electric expansion valves 5 and 6 so as to close any of the plurality of heat exchangers 8a and 8b.

  Here, it is preferable to determine whether or not the above-described low-load state is present as follows. That is, whether or not the condition that the operating frequency W of the compressor 1 is lower than a predetermined value is satisfied, or the discharge pressure Pd detected by the discharge pressure sensor 11 that detects the discharge pressure of the compressor 1 and the suction The controller 13 determines whether or not the condition that the difference from the suction pressure Ps detected by the suction pressure sensor 10 that detects the pressure is smaller than a predetermined value is satisfied. And when satisfy | filling this low load condition, what is necessary is just to give control to the said electric expansion valves 5 and 6 from the said controller 13, and to close either of the said heat exchangers 8a and 8b. .

  During the transition to the dehumidification promoting operation, one of the electric expansion valves 5 or 6 is closed, so that the amount of refrigerant circulating in the refrigeration cycle is reduced and the refrigerant evaporation pressure is lowered. For this reason, the refrigerant is excessively heated, and the refrigerant discharge side superheat degree TdSH increases. Therefore, a program for obtaining the relationship between the opening of the electric expansion valve and the flow rate of the refrigerant as shown in FIG. When the opening degree of the electric expansion valve 5 is Va and the opening degree of the electric expansion valve 6 is Vb1, the total refrigerant flow rate is “Ma + Mb1 = Mb2”. If the electric expansion valve 5 is fully closed from this state, the refrigerant flow rate becomes Mb1, so in this embodiment, the total refrigerant flow rate Mb2 when the opening degree of the electric expansion valve 5 is Va is obtained. Thus, the opening degree of the electric expansion valve 6 is increased from Vb1 to Vb2.

The refrigerant flow rate Ma due to the opening degree Va of the electric expansion valve 5 corresponding to the small-capacity indoor heat exchanger 8a is smaller than the refrigerant flow rate due to the electric expansion valve 6, and thus exceeds the control range of the electric expansion valve 6. It is possible to easily cope with this, and the control range of the electric expansion valve 6 is widened, so that it is possible to suppress a large change in the refrigerant flow rate during the transition to the dehumidification promoting operation.
Thereafter, the electric expansion valve 6 is controlled such that the refrigerant discharge side superheat degree TdSH becomes a predetermined value. Even when the electric expansion valve 6 is closed, the electric expansion valve 5 can be similarly controlled.

  Further, during the execution of the dehumidification promoting operation, the difference between the high pressure Pd and the low pressure Ps detected by the pressure sensors 10 and 11, or the compressor rotational speed W is determined from a predetermined value set in the controller 13 in advance. When it becomes larger, as shown in FIG. 2, the controller 13 stops the dehumidification promoting operation and changes to the normal cooling operation.

  When the dehumidification promotion operation is stopped and the operation is changed to the normal cooling operation, the electric expansion valve 5 is opened when the opening degree of the electric expansion valve 5 which has been fully closed is returned to the previous opening degree as it is. In some cases, the refrigerant flow rate of the whole increases, the refrigerant evaporation pressure rises, and the compressor 1 causes liquid compression. Therefore, the controller 13 performs control so that the opening degree of the electric expansion valve 6 that is not closed is closed by an amount corresponding to an increase in the refrigerant flow rate according to the opening degree of the electric expansion valve 5.

  That is, since the controller 13 incorporates in advance a program for obtaining the relationship between the opening of the electric expansion valve and the flow rate of the refrigerant as shown in FIG. 3, the electric expansion valve 6 that is not closed is installed. When the opening degree of the electric expansion valve 5 is returned to Va from the state where the opening degree is Vb2 and the refrigerant flow rate is Mb2, the flow rate flowing through the electric expansion valve 5 is increased from 0 to Ma. The controller 13 controls the flow rate to flow through the electric expansion valve 6 so as to decrease by the flow rate Ma to be increased.

For this purpose, as is apparent from FIG. 3, the opening degree of the expansion valve 6 may be reduced from Vb2 to Vb1, so that the flow rate flowing through the electric expansion valve 6 is reduced by Ma from the state of Mb2. Mb1. By controlling in this way, it is possible to suppress a change in the flow rate of the refrigerant flowing through the indoor heat exchanger 8 when returning to the normal cooling operation.
Even when the electric expansion valve 6 is closed and opened, the electric expansion valve 5 can be similarly controlled.

  According to the present embodiment described above, since the dehumidification promoting operation function is provided, even if the cooling load is small, the rotation of the compressor is reduced, and the refrigerant circulation rate is reduced, a sufficient air volume is obtained. It becomes possible to dehumidify while supplying.

  Further, at the time of the dehumidification promoting operation, if the electric expansion valve 5 on the small capacity side is closed and the electric expansion valve 6 on the large capacity side is opened to perform the dehumidification promoting operation, the flow rate on the closed expansion valve 5 side is reduced. The amount can be easily compensated for by increasing the opening of the expansion valve 6 on the large capacity side, and the refrigerant flow rate fluctuation in the entire indoor heat exchanger 8 can be reduced.

  Further, when the electric expansion valve 6 on the large capacity side is closed and the electric expansion valve 5 on the small capacity side is opened to perform the dehumidification promoting operation, the predetermined large air volume is maintained even when the load is very small. However, dehumidifying operation is possible. If this load is in a very small state, the amount of refrigerant circulation is also very small. Therefore, it is possible to ensure the necessary refrigerant flow rate with only the small capacity electric expansion valve 5.

  In addition, in the air conditioning apparatus shown in FIG. 1, since the four-way valve 2 is provided, heating operation is also possible. In the air-conditioning apparatus that also performs the heating operation, the configuration shown in FIG. 1 enables not only the above-described dehumidification promoting operation but also an operation that prevents the cool air feeling at the start of the heating operation. Hereinafter, the example of control at the time of the heating operation start in a present Example is demonstrated.

  In the air conditioner shown in FIG. 1, during the heating operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 first flows into the indoor heat exchanger 8 to condense, as indicated by the dotted arrows, and the high-temperature and high-pressure refrigerant. It becomes a liquid refrigerant, evaporates in the rear outdoor heat exchanger 3 depressurized by the electric expansion valve 4, and becomes a low-temperature low-pressure gas refrigerant. Thereafter, a refrigeration cycle returning to the compressor 1 through the accumulator 9 is formed. A predetermined flow rate of air is sucked into the indoor heat exchanger 8 and heated by exchanging heat with the refrigerant flowing through the indoor heat exchanger 8, and the warmed air is blown out indoors for heating.

In such an air conditioner, the controller 13 generally opens the opening of the electric expansion valve 4 so that the compressor 1 can be driven at an operating frequency determined by start control and an appropriate refrigeration cycle can be formed. A heating start operation is performed to adjust the temperature so as to have a predetermined opening.
The indoor heat exchanger 8 is divided into a small capacity heat exchanger 8a and a large capacity heat exchanger 8b, and the electric expansion valves 5 and 6 are arranged in parallel corresponding to the heat exchangers 8a and 8b. Is provided.

  When the heating operation is started, the expansion valve opening Va is fully closed from the controller 13 to the electric expansion valve 5 corresponding to the small capacity side heat exchanger 8a of the indoor heat exchanger 8 divided into different capacities. The heat exchanger 8a connected to the electric expansion valve 5 is closed. By controlling in this way, the refrigerant circulation amount decreases and the refrigerant evaporation pressure decreases, so that the refrigerant is overheated and the discharge side pressure Pd of the compressor 1 increases. Accordingly, since the temperature of the gas refrigerant in the indoor heat exchanger 8 increases, when the refrigerant condenses in the indoor heat exchanger 8, the temperature of the air at a predetermined flow rate that is heated by heat exchange with the refrigerant is further increased. Can prevent the feeling of cold wind.

  Further, when the heating start control operation described above is shifted to a normal heating operation after a predetermined time has elapsed, for example, the controller 13 is controlled so as to cancel the control at the start of the heating operation, and is fully closed. In addition, the electric expansion valve 5 is opened to shift to a normal heating operation.

  Here, in order to shift to the normal heating operation, when the electric expansion valve 5 that has been fully closed is opened, the refrigerant flow rate increases and the discharge pressure Pd of the compressor 1 decreases. In the present embodiment, since a program for obtaining the relationship between the expansion valve opening degree and the flow rate in FIG. 3 is incorporated in the controller 13 in advance, the following control is performed. That is, the opening degree of the electric expansion valve 6 that is not closed and the opening degree of the electric expansion valve 5 that is fully closed are made to correspond to the capacities of the heat exchangers 8a and 8b. The openings Va and Vb1 of the electric expansion valves 5 and 6 are calculated and controlled by the controller 13 so that the flow rate of the refrigerant flowing through 8b is appropriately distributed. Thereby, the change of the refrigerant | coolant flow volume at the time of transfering to normal heating operation can be suppressed.

  Thus, according to this embodiment, it is possible to prevent the feeling of cold air at the start of heating operation. In general, as a measure to prevent a feeling of cool air at the start of heating operation, control is performed to reduce the air volume of the indoor air sucked into the indoor heat exchanger 8. However, in an air conditioner for facilities, it is necessary to always supply a sufficient air volume of a predetermined amount or more, and it is not possible to adopt a measure for preventing cool air feeling by lowering the indoor air volume. For example, even in such an air conditioner for equipment, an operation in which the feeling of cold air is prevented at the start of the heating operation is possible.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 4 is a refrigeration cycle system diagram of the air conditioner in the second embodiment, FIG. 5 is a diagram for explaining the expansion valve opening control and the state of each part in the air conditioner shown in FIG. 4, and FIG. 6 is shown in FIG. It is a characteristic view which shows the relationship between the expansion valve opening degree and refrigerant | coolant flow volume in an air conditioning apparatus.

  The second embodiment is an example in which the indoor heat exchanger 8 is divided into three parts with different capacities to promote dehumidification. 4, parts denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding parts, and the description of the same parts is omitted.

  In the embodiment shown in FIG. 4, the indoor heat exchanger 8 is divided into three, a small capacity heat exchanger 8a, a large capacity heat exchanger 8b, and a medium capacity heat exchanger 8c, and three in parallel from the refrigerant pipe 20. The branched distribution flow paths 21, 22, and 23 are respectively connected. In addition, electric expansion valves 5, 6, and 7 are provided in the distribution flow paths 21, 22, and 23 connected to the heat exchangers 8a to 8c, respectively. As in the case of the first embodiment, the four-way valve 2 does not have to be provided when the air conditioner is used exclusively for cooling operation.

  During the cooling operation, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 condenses in the outdoor heat exchange 3 to become a high-temperature and high-pressure liquid refrigerant, and is decompressed by the electric expansion valves 5, 6, and 7 and then the indoor heat exchanger. 8 (8a-8c) evaporates and becomes a low-temperature and low-pressure gas refrigerant to form a refrigeration cycle that returns to the compressor 1 through the accumulator 9. The indoor heat exchanger 8 receives air of a predetermined flow rate or more, and when the refrigerant flowing in the indoor heat exchanger 8 evaporates, it is cooled by exchanging heat with the refrigerant. It is blown out indoors for cooling.

  Usually, the controller 13 detects the cooling load based on the data from the intake air temperature sensor 14 and the blown air temperature sensor 15, and drives the compressor 1 at the operating frequency determined by the cooling load. Further, the refrigerant discharge side superheat degree TdSH which is the difference between the discharge refrigerant temperature Td detected by the discharge temperature thermistor 12 and the condensation temperature Tc calculated from the refrigerant discharge pressure Pd detected by the discharge pressure sensor is appropriate. The controller 13 is configured to adjust the opening degree of the electric expansion valves 5 to 7 so as to perform a cooling operation or the like so as to have a predetermined value set in advance to form a refrigeration cycle.

  Further, in the second embodiment, similarly to the first embodiment, the function of the dehumidification promoting operation that enables dehumidification even during the low load operation is provided. That is, in a normal cooling operation state in which the refrigerant discharge side superheat degree TdSH is controlled to be a predetermined value, the intake air temperature T1 detected by the intake air temperature sensor 14 is lowered as shown in FIG. The difference between the set pressure T2 is smaller than a predetermined value preset in the controller 13 and the difference between the suction pressure Pd and the suction pressure Ps detected by the suction pressure sensor 10 and the discharge pressure sensor 11, Alternatively, when the compressor rotation speed W becomes smaller than a predetermined value preset in the controller 13, the dehumidification promoting operation is performed.

  In an air conditioner for facilities and the like, a large air volume that is always greater than or equal to a predetermined value is always required. Therefore, a dehumidifying operation during low load operation is difficult with a conventional air conditioner. However, in the present embodiment, since the function of the dehumidification promoting operation is provided, when the dehumidifying operation is required during the low load operation, the controller 13 switches to the dehumidification promoting operation. Hereinafter, the dehumidifying operation function of this embodiment will be described.

  In the air conditioner of the present embodiment, the three electric expansion valves 5 to 7 are provided in parallel as pressure reducing devices, and the indoor heat exchanger 8 is divided into three different capacities corresponding to the expansion valves 5 to 7. Has been. When performing the dehumidification promotion operation, for example, as shown in FIG. 5, the expansion is performed from the controller 13 to the electric expansion valve 5 corresponding to the heat exchanger 8 a having the minimum capacity of the divided indoor heat exchanger 8. The valve opening degree Va is output so as to be fully closed, and the heat exchanger 8a corresponding to the electric expansion valve 5 is closed. By this operation, the heat exchange capability in the indoor heat exchanger 8 is lowered and the suction pressure Ps is lowered, so that condensation in the heat exchangers 8b and 8c through which the refrigerant is circulated is promoted, and the heat exchanger 8b. , 8c can be dehumidified from the air passing through.

  Even if the electric expansion valve 5 is closed, the difference between the intake air temperature T1 detected by the intake air temperature sensor 14 and the set temperature T2 is smaller than a predetermined value set in the controller 13 in advance. When the difference between the discharge pressure Pd and the suction pressure Ps detected by the suction pressure sensor 10 and the discharge pressure sensor 11 or the compressor rotational speed W becomes smaller than a predetermined value preset in the controller 13. Is then output from the controller 13 to the electric expansion valve 7 corresponding to the heat exchanger 8c divided into small capacities so that the expansion valve opening Vc1 is fully closed. The heat exchanger 8c corresponding to is also closed. By this operation, the heat exchange capability in the indoor heat exchanger 8 is further reduced, so that dew condensation is promoted in the heat exchanger 8b through which the refrigerant flows, and dehumidification from the air passing through the heat exchanger 8b is promoted. it can.

  Instead of closing from the electric expansion valve 5 corresponding to the small capacity side heat exchanger 8a, the electric expansion valve 6 corresponding to the large capacity side heat exchanger 8b or from the medium capacity heat exchanger 8c. You may make it close from the electric expansion valve 7 corresponding to. If the large-capacity heat exchanger 8b or the medium-capacity heat exchanger 8c is closed as described above, the heat exchanging capacity in the indoor heat exchanger 8 is further rapidly reduced, and the refrigerant suction pressure Ps. Therefore, even in the case where the refrigerant circulation rate further decreases due to a low load, it is possible to promote condensation in the heat exchanger 8a or the like in which the refrigerant is circulating, and the heat exchanger on the small capacity side The dehumidification in 8a can be promoted.

  In this embodiment, the indoor heat exchanger 8 is composed of three heat exchangers 8a, 8b, and 8c having different capacities, so that the electric expansion valves 5 to 7 are controlled according to the state of the load. While supplying a sufficient amount of air over a wider range, not only during normal operation, but also from a state where the load is slightly reduced to a state where the load is greatly reduced, that is, a state where the compressor rotational speed is greatly reduced. Dehumidification is possible.

  At the time of transition to the dehumidification promoting operation, the amount of refrigerant circulating in the refrigeration cycle is reduced and the refrigerant evaporation pressure is reduced as in the first embodiment. For this reason, the refrigerant is excessively heated, and the refrigerant discharge side superheat degree TdSH increases. Therefore, a program for obtaining the relationship between the opening of the electric expansion valve and the refrigerant flow rate as shown in FIG. When the opening degree of the electric expansion valve 5 is Va, the opening degree of the electric expansion valve 6 is Vb1, and the opening degree of the electric expansion valve 7 is Vc1, the total refrigerant flow rate is “Ma + Mc1 + Mb1 = Mb3”. If the electric expansion valve 5 is fully closed from this state, the refrigerant flow rate becomes “Mc1 + Mb1”. Therefore, in this embodiment, the total refrigerant flow rate Mb3 when the opening degree of the electric expansion valve 5 is Va. Thus, the controller 13 controls the opening of the electric expansion valve 6 from Vb1 to Vb2 and the opening of the electric expansion valve 7 from Vc1 to Vc2.

  When the electric expansion valve 5 is fully closed and the opening degrees of the electric expansion valves 6 and 7 are Vb1 and Vc1, the total refrigerant flow rate is “Mb1 + Mc1 = Mb3”. If the electric expansion valve 7 is fully closed from this state, the refrigerant flow rate becomes Mb1 only, so that the opening degree of the electric expansion valve 7 becomes the total refrigerant flow rate Mb3 obtained by adding the refrigerant flow rate Mc1 in the state of Vc1. Thus, the opening degree of the electric expansion valve 6 is increased from Vb1 to Vb3. Thereby, the change of the refrigerant | coolant flow rate at the time of the transition to a dehumidification promotion driving | operation can be suppressed.

  In this embodiment, since the indoor heat exchanger 8 is divided into three heat exchangers of different capacities, the opening degree is set with respect to the refrigerant flow rate that decreases corresponding to the electric expansion valves that are sequentially closed. The opening adjustment amount of the electric expansion valve that is increased can be increased step by step. Therefore, there is a margin in the control of the electric expansion valve.

  During the dehumidification promoting operation, the difference between the suction pressure Ps and the discharge pressure Pd detected by the suction pressure sensor 10 and the discharge pressure sensor 11 or the compressor rotational speed W is preset in the controller 13. When it becomes higher than the predetermined value, the controller 13 stops the dehumidification promoting operation and returns to the normal cooling operation.

  Here, when the electric expansion valve 5 or the like that has been fully closed is opened in order to return to the normal cooling operation, the refrigerant flow rate increases and the refrigerant evaporation pressure rises. May occur. In this embodiment, since the controller 13 incorporates a program for obtaining the relationship between the expansion valve opening and the flow rate as shown in FIG. The opening degree of each of the electric expansion valves 5, 6, 7 is distributed so that the flow rate of the refrigerant flowing through the unexpanded electric expansion valves 6, 7 is distributed according to the capacity of each of the heat exchangers 8 a to 8 c. Va, Vb1, and Vc1 are calculated and the opening degree is controlled by the controller 13. Thereby, the refrigerant | coolant flow rate change at the time of a return to normal cooling operation can also be controlled appropriately.

  Also in the second embodiment, as shown in FIG. 4, the air conditioner includes the four-way valve 4 and is capable of heating operation. Therefore, as in the first embodiment, only the above-described dehumidification promoting operation is performed. In addition, an operation in which the feeling of cold air is prevented at the start of the heating operation is also possible.

  In this embodiment, the indoor heat exchanger 8 is divided into three parts, and an electric expansion valve is provided corresponding to each of the divided heat exchangers. However, the indoor heat exchanger 8 is divided into four parts. It is also possible to make it more than division.

  When the indoor heat exchanger 8 is divided into four or more parts, the difference between the intake air temperature T1 detected by the intake air temperature sensor 14 and the set temperature T2 is larger than a predetermined value preset in the controller 13. Or until the difference between the suction pressure Ps and the discharge pressure Pd detected by the suction pressure sensor 10 and the discharge pressure sensor 11 or the compressor rotational speed W becomes higher than a predetermined value set in the controller 13 in advance. The divided heat exchangers 8a, 8b, 8c,... May be closed sequentially from the electric expansion valve corresponding to the heat exchanger on the small capacity side. The electric expansion valve that is not closed is then controlled so that the refrigerant discharge side superheat degree TdSH becomes a predetermined value.

When the indoor heat exchanger 8 is divided into three or more parts, it is not always necessary to use different capacities. By controlling the number of heat exchangers to be closed, the dehumidification promoting operation according to the load condition is performed. It becomes possible.
Also in the second embodiment described above, the same effects as in the first embodiment can be obtained. Further, according to the second embodiment, even if the load changes greatly, dehumidification can be performed while supplying a sufficient air volume over a wider range in a fine manner corresponding to the change in the load.

1: compressor,
2: Four-way valve,
3: Outdoor heat exchanger,
4, 5, 6, 7: electric expansion valve,
8: Indoor heat exchanger,
8a: a small capacity heat exchanger, 8b: a large capacity heat exchanger, 8c: a medium capacity heat exchanger,
9: Accumulator,
10: suction pressure sensor, 11: discharge pressure sensor,
12: Discharge temperature thermistor,
13: Controller (control means),
14: intake air temperature sensor, 15: blown air temperature sensor,
20: Refrigerant piping, 21, 22, 23: Distribution flow path.

Claims (11)

In an air conditioner configured to form a refrigeration cycle by sequentially connecting a compressor, an outdoor heat exchanger, an electric expansion valve, and an indoor heat exchanger with a refrigerant pipe,
The indoor heat exchanger is constituted by a plurality of divided heat exchangers, and the plurality of heat exchangers are connected to distribution channels in which the refrigerant pipes are branched in parallel, An electric expansion valve, and an intake air temperature sensor for detecting the temperature of the air flowing into the indoor heat exchanger;
A discharge pressure sensor for detecting a discharge pressure of the compressor;
A suction pressure sensor for detecting the suction pressure of the compressor;
When the difference between the temperature detected by the intake air temperature sensor and the set temperature is smaller than a predetermined value and the dehumidifying operation is performed at the time of low load operation, the distribution flow path connected to any of the plurality of heat exchangers And an air conditioner comprising: control means for controlling the electric expansion valve provided on the door to be closed.   The air conditioner according to claim 1, wherein the air conditioner is an equipment air conditioner that always requires a blown air volume equal to or greater than a predetermined air volume, and the compressor is configured to be capable of controlling the rotational speed, Further, the control means is detected when the difference between the temperature detected by the intake air temperature sensor and a set temperature is smaller than a predetermined value and the operating frequency of the compressor is lower than a predetermined value, or detected by the discharge pressure sensor. An air conditioner characterized in that, when a dehumidifying operation is performed when a difference between a discharge pressure and a suction pressure detected by the suction pressure sensor is smaller than a predetermined value, one of the electric expansion valves is controlled to be closed. apparatus.   3. The air conditioner according to claim 1, wherein when the control unit closes any one of the electric expansion valves, the control unit controls the opening degree of the electric expansion valve that does not close. Air conditioner.   The air conditioning apparatus according to any one of claims 1 to 3, wherein when the control means closes any of the electric expansion valves, the control means is a flow amount corresponding to the flow rate of the electric expansion valve to be closed, An air conditioner that controls the opening degree so that the flow rate of an electric expansion valve that does not close increases.   5. The air conditioner according to claim 1, wherein the indoor heat exchanger includes a plurality of heat exchangers having different capacities.   6. The air conditioner according to claim 5, wherein the control means is configured to close from the electric expansion valve corresponding to a heat exchanger on a small capacity side when closing any of the electric expansion valves. An air conditioner characterized by being made.   The air conditioner according to any one of claims 1 to 6, wherein the indoor heat exchanger is configured by a heat exchanger having three or more divisions.   3. The air conditioner according to claim 2, wherein when the control means closes any of the electric expansion valves, a difference between a temperature detected by the suction air temperature sensor and a set temperature is larger than a predetermined value. And the difference between the discharge pressure detected by the discharge pressure sensor and the suction pressure detected by the suction pressure sensor becomes larger than the predetermined value when the operating frequency of the compressor becomes higher than the predetermined value. In this case, the air is controlled to increase the valve opening of the closed electric expansion valve and to decrease the valve opening of the electric expansion valve that has increased the valve opening. Harmony device.   The air conditioner according to claim 8, wherein the valve opening degree of the electric expansion valve that has been increased while the valve opening degree of the electric expansion valve that has been closed is increased. An air conditioner that controls the flow rate of refrigerant flowing through the indoor heat exchanger before and after the release to coincide with each other.   The air conditioner according to any one of claims 1 to 9, further comprising a four-way valve so as to be capable of heating operation, wherein the control means includes a plurality of components constituting the indoor heat exchanger when starting the heating operation. Start control for closing the electric expansion valve corresponding to a part of the heat exchanger is performed, and then control to open the closed electric expansion valve when releasing the start control. An air conditioner characterized by:   The air conditioner according to claim 10, wherein when the start-up control is released, the control means sets the valve opening degree of the non-closed electric expansion valve when the closed electric expansion valve is opened. An air conditioner that controls the flow rate of refrigerant to flow through the indoor heat exchanger before and after the start control is released to be reduced.

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