JP5901107B2 - Multi-type air conditioning system - Google Patents

Description

  The present invention relates to a multi-type air conditioner having a plurality of indoor units for one outdoor unit.

There is known a multi-type air conditioning system in which a plurality of indoor unit units are connected in parallel to a single outdoor unit. In this air conditioning system, a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe are arranged between an outdoor unit and an indoor unit, and the high-pressure gas is connected to the outdoor heat exchanger and the gas pipe side of each indoor heat exchanger, respectively. It is possible to switch between the pipe and the low-pressure gas pipe so as to selectively communicate with each other. During operation of this air conditioning system, cooling operation is performed when a low-pressure gas pipe is connected to the indoor unit, and heating operation is performed when a high-pressure gas pipe is connected to the indoor unit. Here, switching between the low pressure gas pipe and the high pressure gas pipe has been performed by a switching valve called a diversion controller (see, for example, Patent Documents 1 and 2).
With such a configuration, it is possible to mix a plurality of indoor unit units simultaneously with those for cooling operation and those for heating.

  Conventionally, in such a multi-type air conditioning system including a plurality of indoor unit units, indoor unit units for cooling operation and indoor unit units for heating operation are mixed in a limited period in spring and autumn. there were. However, in recent years, a cooling operation may be performed throughout the year in a space that accommodates devices that exhibit a large amount of heat inside, such as a server room that houses a server device of a computer. In such a case, in a multi-type air conditioning system, in most indoor unit units installed in a normal office space, etc., while performing heating or cooling according to the season, always cooling operation There were some indoor unit units to perform.

JP 2005-300006 A JP 2009-210139 A

As described above, in a multi-type air conditioning system in which there are indoor unit units that perform cooling operation throughout the year, heating is performed in most indoor unit units installed in normal office spaces, especially in winter. Cooling operation is performed only with some indoor unit units. As described above, when the operation is performed mainly by heating, the outdoor unit is used as an evaporator. As a result, the indoor unit that performs heating functions as a condenser, and the high-pressure liquid refrigerant or the gas-liquid two-phase refrigerant after heat exchange is conveyed.
Then, the refrigerant sent out from the indoor unit flows into the heat exchanger of the outdoor unit where a larger temperature difference (enthalpy) can be obtained than the heat exchanger of the indoor unit performing cooling. As a result, there arises a problem that the amount of refrigerant is relatively reduced in the heat exchanger of the indoor unit performing cooling. Also, when the other indoor unit is performing the heating operation, the amount of supercooling of the refrigerant is smaller than when the other indoor unit is also performing the cooling operation. In, the ability is relatively reduced.

  In addition, the outdoor unit and the indoor unit that is performing the cooling operation function as an evaporator, but the suction temperature of the outdoor unit differs from the suction temperature of the indoor unit. Will exist. However, the evaporation temperature of the entire system is stable to the lowest evaporation temperature. Thereby, when the suction temperature of the indoor unit becomes below the freezing point, the heat exchanger freezes. As a result, the cooling operation is interrupted, the ice-freezing operation is performed, and then the cooling operation is resumed. Therefore, the start / stop operation is repeated, and the cooling capacity of the indoor unit that is performing the cooling operation is reduced. Occurs.

For such a problem, in the technique described in Patent Document 1, in order to ensure the cooling capacity in the indoor unit during the cooling operation, the expansion valve in the indoor unit during the cooling operation is intentionally opened, By increasing the number of rotations of the compressor, the circulation amount of the refrigerant is increased to increase the cooling capacity.
However, such a method is realized by control (software) to the last, depending on the total number of indoor unit units constituting the multi-type air conditioning system, the number of indoor unit units that perform constant cooling operation, and the like. The expansion valve opening of the indoor unit and the rotation speed of the compressor must be set optimally. For this reason, the expansion valve opening degree of the indoor unit and the rotation speed of the compressor have to be set for each individual air conditioning system, which takes time and increases the product cost.
The present invention has been made on the basis of such a technical problem. In an air conditioning system including a plurality of indoor unit units, the present invention is easy and inexpensive even when there are indoor unit units that perform cooling operation at all times. An object of the present invention is to provide a multi-type air conditioning system capable of ensuring sufficient cooling capacity.

The present invention based on such an object relates to a multi-type air conditioning system including an outdoor unit and an indoor unit in which a plurality of outdoor units are connected in parallel to the outdoor unit. The outdoor unit includes a compressor and an outdoor heat exchanger that exchanges heat between the outside air and the refrigerant, and is connected to the discharge side of the compressor to supply a high-pressure gas refrigerant. A gas pipe, a low pressure gas pipe that is connected to the suction side of the compressor and feeds a refrigerant in a gas state at a pressure lower than that of the high pressure gas pipe, and a liquid pipe that feeds a liquid state refrigerant are led out. The plurality of indoor unit units includes an indoor heat exchanger that exchanges heat between the indoor air and the refrigerant, and at least one indoor unit is dedicated to cooling, and heat exchange is performed on the refrigerant supplied from the liquid pipe. An evaporating pressure adjusting mechanism for adjusting the evaporating pressure in the indoor heat exchanger that performs cooling operation by switching the flow direction of the refrigerant in the high-pressure gas pipe, the low-pressure gas pipe, and the liquid pipe. A cooling / heating operation switching mechanism for selectively switching between heating operation is provided .
Here, the evaporating pressure adjusting mechanism is installed in the indoor unit that performs only the cooling operation. The evaporating pressure adjusting mechanism branches the low-pressure gas pipe into a plurality of branch pipes between the indoor heat exchanger and the outdoor unit, and provides openable and closable valves on the branch pipes to adjust the opening and closing of these valves. Thus, the evaporation pressure of the refrigerant in the indoor heat exchanger is adjusted.
In this way, by adjusting the evaporation pressure in the indoor heat exchanger with the evaporation pressure adjusting mechanism, the outside air temperature is low, heating operation is performed in another indoor unit, and the outdoor unit functions as an evaporator However, in an indoor unit that is provided with an evaporation pressure adjusting mechanism and is performing a cooling operation, the suction temperature can be prevented from becoming below freezing point, and the indoor heat exchanger can be prevented from freezing.
In such a configuration, the indoor unit that performs only the cooling operation may be provided with an evaporation pressure adjusting mechanism, and the indoor unit that performs switching between the cooling operation and the heating operation may be provided with a cooling / heating operation switching mechanism.
In one form of the above-described multi-type air conditioning system, at least one indoor unit is configured to supply the cooling / heating operation switching mechanism with the refrigerant supplied from the liquid pipe to the indoor heat exchanger during the cooling operation. The supercooling heat exchanger which supercools by exchanging heat with the refrigerant | coolant which passed through is provided. The indoor unit provided with this supercooling heat exchanger includes an expansion valve that adjusts the flow rate of the refrigerant passing through the indoor heat exchanger, and the temperature of the refrigerant on the inlet side and outlet side of the indoor heat exchanger during heating operation. The opening of the expansion valve is adjusted so that the difference becomes a predetermined specified value. During cooling operation, the temperature difference between the refrigerant on the outlet side and the inlet side of the supercooling heat exchanger is determined in advance. And a controller that adjusts the opening of the expansion valve. As described above, at least one indoor unit is provided with a supercooling heat exchanger, and the refrigerant in the liquid pipe is brought into a supercooled state by the supercooling heat exchanger during the cooling operation, so that the liquid refrigerant having a low enthalpy is obtained. Can be sent to the indoor unit.

  Here, the air conditioning operation switching mechanism includes a first port connected to the high pressure gas branch pipe branched from the main pipe of the high pressure gas pipe, a second port connected to the indoor heat exchanger side, and a main pipe of the low pressure gas pipe. A four-way valve formed with a third port connected to the low-pressure gas branch pipe branched from the first low-pressure gas branch pipe and a fourth port connected to the low-pressure bypass pipe joining the low-pressure gas branch pipe; A first on-off valve provided on the high-pressure gas branch pipe, one end connected to the upstream side of the high-pressure gas branch pipe from the first on-off valve, and the other end connected to the downstream side of the high-pressure gas branch pipe from the first on-off valve A position where one end is connected to the high-pressure bypass pipe bypassing the first on-off valve, the high-pressure gas branch pipe between the downstream side of the high-pressure bypass pipe and the first port of the four-way valve, and the low-pressure bypass pipe is connected The other end is connected to the low-pressure gas branch pipe on the downstream side. May comprise a pressure bypass pipe, and a second on-off valve provided on the high-low pressure bypass pipe, a.

Further, in another form of the multi-type air conditioning system described above, at least one indoor unit unit has a refrigerant sent to the low-pressure gas pipe via the indoor heat exchanger in the cooling / heating operation switching mechanism during the cooling operation. An overheat heat exchanger that is heated by exchanging heat with the refrigerant fed from the high-pressure gas pipe is provided .

In this way, at least one indoor unit is equipped with a superheat exchanger, and the high-temperature and high-pressure liquid refrigerant condensed in the indoor heat exchanger can be superheated, so that it can be actively flown to the low-pressure gas pipe side. . At this time, even if the liquid phase remains in the refrigerant, the unevaporated portion of the liquid refrigerant can be evaporated by heat exchange in the supercooling heat exchanger.
Furthermore, since the superheat heat exchanger becomes a pressure loss and the evaporation temperature of the refrigerant in the indoor heat exchanger rises, the indoor heat exchanger becomes difficult to freeze.

Incidentally, where an indoor unit equipped with an over-heat heat exchanger, an expansion valve for adjusting the flow rate of the refrigerant passing through the indoor heat exchanger, in the heating operation, the indoor heat exchanger inlet and outlet sides of the to be a specified value which temperature difference is a predetermined refrigerant, by adjusting the opening degree of the expansion valve, at the time of cooling operation, the temperature difference between the refrigerant outlet side and the inlet side of the over-heat exchanger is predetermined And a control unit that adjusts the opening of the expansion valve so as to have a specified value.

ADVANTAGE OF THE INVENTION According to this invention, it can prevent that an indoor heat exchanger freezes by adjusting the evaporation pressure in an indoor heat exchanger with an evaporation pressure adjustment mechanism. As a result, it is not necessary to interrupt the cooling operation and perform the ice-breaking operation, so that the cooling operation can be performed continuously, and the cooling capacity of the indoor unit that always performs the cooling operation can be increased.
In addition, the above effect can be obtained by the hardware configuration in which the indoor unit that performs only the cooling operation is provided with an evaporation pressure adjusting mechanism, and the indoor unit that is switched between the cooling operation and the heating operation is provided with a cooling / heating switching mechanism. Therefore, there is no need to set software according to each air conditioning system, installation is easy, and costs can be reduced.

  Further, according to the present invention, by providing the supercooling heat exchanger in at least one indoor unit, the refrigerant in the liquid pipe is supercooled by the supercooling heat exchanger during the cooling operation, and the liquid with low enthalpy The refrigerant can be sent to the indoor unit. Thereby, in an indoor unit, sufficient cooling capacity can be exhibited, ensuring the amount of refrigerant circulation. This can also prevent the liquid refrigerant from returning to the compressor of the outdoor unit through the liquid pipe, prevent the compressor from being broken, and improve the system reliability.

Furthermore, according to the present invention, it is possible to positively flow to the low-pressure side gas pipe side by providing the superheat exchanger in at least one indoor unit. At this time, even if the liquid phase remains in the refrigerant, the unevaporated portion of the liquid refrigerant can be evaporated by heat exchange in the superheat heat exchanger. As a result, the amount of refrigerant flowing from the indoor heat exchanger to the low-pressure gas pipe can be increased, and even if the amount of refrigerant is increased, the unevaporated portion of the liquid refrigerant can be reliably evaporated, so the compressor is broken. Can be prevented. Thereby, in an indoor unit, sufficient cooling capacity can be exhibited, ensuring the amount of refrigerant circulation.
Furthermore, since the superheat heat exchanger becomes a pressure loss and the evaporation temperature of the refrigerant in the indoor heat exchanger rises, the indoor heat exchanger becomes difficult to freeze. As a result, it is not necessary to interrupt the cooling operation and perform the ice-breaking operation, so that the cooling operation can be performed continuously, and the cooling capacity of the indoor unit that always performs the cooling operation can be increased.

It is a figure for demonstrating the whole structure of the multi-type air conditioning system in 1st embodiment. (A) is a figure which shows the structure of a shunt controller, (b) is a figure which shows the example of the opening / closing state of each part according to an operation mode. (A) is a figure which shows the structure of a gas pipe pressure control kit, (b) is a figure which shows the example of the opening-and-closing state of each part according to an operation mode. It is a figure which shows the structure of the control in a multi type air conditioning system. (A) is a figure which shows the flow of the refrigerant | coolant in the shunt controller at the time of cooling operation, (b) is a figure which shows the flow of the refrigerant | coolant in the shunt controller at the time of heating operation. It is a figure which shows the flow of control of the operation pattern in a gas pipe pressure control kit. It is a figure which shows the structure of the shunt controller in 2nd embodiment. (A) is a figure which shows the flow of the refrigerant | coolant in the shunt controller at the time of cooling operation, (b) is a figure which shows the flow of the refrigerant | coolant in the shunt controller at the time of heating operation. It is a figure which shows the flow of switching of the opening degree control of the expansion valve according to cooling and heating. It is a figure which shows the structure of the shunt controller in 3rd embodiment. (A) is a figure which shows the flow of the refrigerant | coolant in the shunt controller at the time of cooling operation, (b) is a figure which shows the flow of the refrigerant | coolant in the shunt controller at the time of heating operation.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
[First embodiment]
FIG. 1 is a diagram for explaining the overall configuration of a multi-type air conditioning system according to the present embodiment.
As shown in FIG. 1, a multi-type air conditioning system 200 includes one outdoor unit 1, a plurality of indoor unit units 3,..., A high-pressure gas pipe (main pipe) 5 that connects them, and a low-pressure gas pipe. (Main pipe) 7 and liquid pipe 9 are provided.

  The outdoor unit 1 mainly includes a compressor 10, outdoor expansion valves (expansion valves) 11a and 11b, outdoor heat exchangers 12a and 12b, outdoor four-way valves 14a and 14b, an accumulator 20, a receiver 23, and a supercooler 25. ing.

  The outdoor heat exchangers 12a and 12b exchange heat between the outdoor air and the refrigerant, and operate as a condenser or an evaporator depending on the state of the refrigerant that passes therethrough. Between the outdoor heat exchangers 12a and 12b and the liquid pipe 9 between the receivers 23 and in the vicinity of the outdoor heat exchangers 12a and 12b, outdoor expansion valves (expansion valves) 11a and 11b, respectively. Is provided. Electronic expansion valves are used as the outdoor expansion valves 11a and 11b.

The pipes connected to the receiver 23 side of the outdoor expansion valves 11 a and 11 b join at the junction 9 a of the liquid pipe 9.
In each of the outdoor heat exchangers 12a and 12b, liquid pipe side temperature sensors 30a and 30b provided on the liquid pipe 9 side, and four-way valve side temperature sensors 32a and 32b provided on the outdoor four-way valves 14a and 14b side, respectively. Is provided.
Further, an outdoor temperature sensor 34 for measuring the outdoor temperature, that is, the outdoor temperature, is provided in the vicinity of the outdoor heat exchangers 12a and 12b.

  For example, a scroll compressor is preferably used as the compressor 10. In the compressor 10, the refrigerant compressed by the compressor 10 becomes a high-pressure gas refrigerant and is discharged to the high-pressure gas pipe 5. The high pressure gas pipe 5 is provided with a high pressure sensor PSH for measuring the pressure of the discharged refrigerant. Further, the discharge pipe of each compressor 10 is provided with a discharge pipe temperature sensor 36 for measuring the discharge pipe temperature.

  The high-pressure gas pipe 5 located in the outdoor unit 1 branches at branch points 5a and 5b, and the branch pipes 6a and 6b are connected to the outdoor four-way valves 14a and 14b at the high-pressure gas pipe port 14-1. . The outdoor four-way valves 14a and 14b include an outdoor heat exchanger side port 14-2 connected to the outdoor heat exchangers 12a and 12b, and an outdoor low pressure gas branch pipe 15a that branches at a branch point 7d of the low pressure gas pipe 7, respectively. , 15b, a low pressure gas pipe side port 14-3, and a bypass pipe side port 14-4 connected to the outdoor low pressure gas branch pipes 15a, 15b via strainers 17a, 17b and capillary tubes 18a, 18b. It has.

  In the outdoor heat exchangers 12a and 12b, the liquid pipe 9 is connected to the side opposite to the side connected to the outdoor four-way valves 14a and 14b. The liquid pipe 9 in the outdoor unit 1 is provided with a receiver 23 that stores the liquid refrigerant and a supercooler 25 that supercools the refrigerant flowing through the liquid pipe 9 during the cooling operation. The subcooler 25 takes out a part of the liquid refrigerant flowing through the liquid pipe 9 and supercools the liquid refrigerant flowing through the liquid pipe 9 with the refrigerant that is expanded and vaporized by the expansion valve 25a and cooled. The gas refrigerant used for subcooling and vaporized is returned to the accumulator 20.

A plurality of indoor unit units 3 are provided.
Each indoor unit 3 includes an indoor heat exchanger 40 that exchanges heat with room air. The indoor heat exchanger 40 is provided with temperature sensors 33 and 35 for measuring the temperature before and after the indoor heat exchanger 40. In the vicinity of the indoor heat exchanger 40, an indoor temperature sensor 37 for measuring the indoor temperature is provided. An indoor expansion valve 42 is provided in the liquid refrigerant branch pipe 44 connecting the indoor heat exchanger 40 and the liquid pipe 9.

Among the plurality of indoor unit units 3, 3,..., An indoor unit 3C that is installed in a server room or the like and performs only a cooling operation has a gas pipe pressure control kit (evaporation pressure) connected only to the low pressure gas pipe 7. Adjustment mechanism) 100 is provided.
In the plurality of indoor unit units 3, 3,..., The high-pressure gas pipe 5 and the low-pressure gas pipe 7 are provided between the indoor unit 3 other than the indoor unit 3C that performs only the cooling operation, and the outdoor unit 1. A diversion controller (cooling / heating operation switching mechanism) 46 is provided for switching the above.

  As shown in FIG. 2, the diversion controller 46 includes an indoor four-way valve 48. The indoor four-way valve 48 includes a high-pressure gas pipe port 48-1 (first port) connected to the high-pressure gas branch pipe 5c branched from the main pipe of the high-pressure gas pipe 5, and a room connected to the indoor heat exchanger 40 side. A heat exchanger side port 48-2 (second port), a low pressure gas pipe port 48-3 (third port) connected to the indoor side low pressure gas branch pipe 7c branched from the main pipe of the low pressure gas pipe 7, A low-pressure bypass pipe port 48-4 (fourth port) connected to the low-pressure bypass pipe 50 that joins the midway position 49 of the indoor-side low-pressure gas branch pipe 7c.

  The indoor four-way valve 48 communicates the high-pressure gas pipe port 48-1 and the low-pressure bypass pipe port 48-4 during the cooling operation, and the indoor heat exchanger side port 48-2 and the low-pressure gas pipe port 48-3. Communicate. The indoor four-way valve 48 communicates the high-pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 during heating operation, and the low-pressure gas pipe port 48-3 and the low-pressure bypass pipe port 48-. 4 is communicated.

  The high-pressure gas branch pipe 5 c on the upstream side of the indoor four-way valve 48 is provided with a high-pressure gas branch pipe on-off valve (first on-off valve) 52. A high-pressure gas branch pipe bypass pipe (high-pressure bypass pipe) 54 is formed so as to bypass the high-pressure gas branch pipe on-off valve 52, and a first capillary tube 55 is provided in the high-pressure gas branch pipe bypass pipe 54. Yes. One end of the high-pressure gas branch pipe bypass pipe 54 is connected to the upstream side of the high-pressure gas branch pipe 5c from the high-pressure gas branch pipe on-off valve 52, and the other end is connected to the downstream side of the high-pressure gas branch pipe on-off valve 52c. The end is connected to bypass the on-off valve 52 for the high-pressure gas branch pipe.

  A second capillary tube 57 is provided in the low pressure bypass pipe 50 on the downstream side of the indoor four-way valve 48.

  Between the high-pressure gas branch pipe 5c upstream of the high-pressure gas branch pipe bypass pipe 54 and the indoor low-pressure gas branch pipe 7c downstream of the low-pressure bypass pipe 50 (downstream of the midway position 49), A bypass pipe 58 is provided. The first high / low pressure bypass pipe 58 is provided with a first high / low pressure bypass opening / closing valve 60 and a third capillary tube 62 in order from the high pressure gas branch pipe 5c side toward the indoor side low pressure gas branch pipe 7c side. .

  One end is connected to the high-pressure gas branch pipe 5c between the downstream side of the high-pressure gas branch pipe bypass pipe 54 and the high-pressure gas pipe port 48-1 of the indoor four-way valve 48, and the downstream side of the low-pressure bypass pipe 50 (at the midway position 49). A second high / low pressure bypass pipe (high / low pressure bypass pipe) 63 whose other end is connected to the indoor side low pressure gas branch pipe 7c on the downstream side is provided. The second high / low pressure bypass pipe 63 includes a second high / low pressure bypass open / close valve (second open / close valve) 64 and a fourth capillary tube 65 from the high pressure gas branch pipe 5c side toward the indoor side low pressure gas branch pipe 7c side. Are provided in order.

3A, the gas pipe pressure control kit 100 is provided in the indoor-side low-pressure gas branch pipe 7c between the indoor unit 3c and the outdoor unit 1.
The indoor-side low-pressure gas branch pipe 7c branches into a plurality of branch pipes 102a, 102b, and 102c in the gas pipe pressure control kit 100 portion. The gas pipe pressure control kit 100 includes a plurality of, in the present embodiment, three electromagnetic valves (valves) 101a, 101b, and 101c.

  As shown in FIG. 4, the air conditioning system 200 includes an outdoor control device CL1 that controls the outdoor unit 1 and an indoor control device CL2 that controls the indoor unit 3. In the present embodiment, one indoor control device CL <b> 2 is provided for each indoor unit 3. The outdoor control device CL1 and the indoor control device CL2 communicate with each other. Note that only one of the outdoor heat exchangers 12a and 12b and the outdoor four-way valves 14a and 14b is shown in FIG.

The outdoor control device CL1 includes a control unit 70 and an input unit 72.
The control unit 70 calculates each control value based on the data obtained from the input unit 72. This control value is sent to each control device such as the outdoor expansion valve 11a, the outdoor fan F1, the outdoor four-way valve 14a, and the compressor 10. Each calculation result of the control unit 70 is sent to the input unit 82 of the indoor control device CL2.
The input unit 72 includes a liquid pipe side temperature sensor 30a provided in the outdoor heat exchanger 12a, a four-way valve side temperature sensor 32a, an outdoor temperature sensor 34 provided in the vicinity of the outdoor heat exchanger 12a, and a discharge from the compressor 10. The output values of the discharge pipe temperature sensor 36, the high pressure sensor PSH, the low pressure sensor PSL provided on the upstream side of the accumulator 20, and the suction pipe temperature sensor 38 are input.

The indoor control device CL2 includes a control unit 80 and an input unit 82.
The control unit 80 calculates each control value based on the data obtained from the input unit 82. This control value is sent to control target devices such as the indoor expansion valve 42, the indoor fan F2, the indoor four-way valve 48 of the flow dividing controller 46, and the electromagnetic valves 101a, 101b, 101c of the gas pipe pressure control kit 100. Each calculation result of the control unit 80 is sent to the input unit 72 of the outdoor control device CL1.
The output values of the temperature sensors 33 and 35 and the indoor temperature sensor 37 provided in the indoor heat exchanger 40 are input to the input unit 82.

  The outdoor control device CL1 and the indoor control device CL2 include at least a CPU as an arithmetic processing device, a RAM as a main storage device, and a recording medium on which a program for operating the air conditioning system 200 is recorded. . The outdoor control device CL1 and the indoor control device CL2 operate the air conditioning system 200 in accordance with the purpose by reading the program recorded in the storage medium and executing information processing / calculation processing. Let

In such an air conditioning system 200, the indoor unit 3 including the diversion controller 46 can be switched between a cooling operation and a heating operation according to the season.
FIG. 2B illustrates the indoor four-way valve 48, the high-pressure gas branch pipe on-off valve 52, the first during cooling operation (when the outside air temperature is high: high outside air, when the outside air temperature is low: low outside air) and during the heating operation. It is a figure which shows the example of a setting of the opening / closing state of the high / low pressure bypass opening / closing valve 60 and the 2nd high / low pressure bypass opening / closing valve 64.
As shown in FIG. 2B, during the cooling operation, the first high / low pressure bypass on / off valve 60, the indoor four-way valve 48, the second high / low pressure bypass on / off valve 64, and the high pressure are not limited to high outside air and low outside air. All the gas branch pipe on-off valves 52 are closed.
During heating operation, among the first high / low pressure bypass opening / closing valve 60, the indoor four-way valve 48, the second high / low pressure bypass opening / closing valve 64, and the high-pressure gas branch pipe opening / closing valve 52, the indoor four-way valve 48, for the high-pressure gas branch pipe. Only the opening / closing valve 52 is opened, and the first high / low pressure bypass opening / closing valve 60 and the second high / low pressure bypass opening / closing valve 64 are closed.

  The high-pressure gas refrigerant that has flowed from the outdoor unit 1 to the outdoor heat exchangers 12a and 12b of the indoor unit 3 exchanges heat with the outside air, dissipates heat, and is condensed and liquefied. In this case, both the outdoor expansion valves 11a and 11b are fully opened, and the condensed high-pressure liquid refrigerant passes through the receiver 23 and passes through the receiver 23 and is supercooled by the subcooler 25, and then the liquid pipe 9 Then, it is guided to the indoor unit 3. If the liquid pipe 9 connecting the outdoor unit 1 and the indoor unit 3 is long, a supercooler 25 is attached to avoid evaporation of the liquid refrigerant in the liquid pipe 9. desirable.

The high-pressure liquid refrigerant that has flowed into the indoor unit 3 that is in the cooling operation flows as follows.
As indicated by a thick line in FIG. 5A, the high-pressure liquid refrigerant branches into the liquid refrigerant branch pipe 44 connected to the indoor unit 3, and is then throttled by the indoor expansion valve 42 of the indoor unit 3. Be made. Thereafter, the liquid refrigerant evaporates in the indoor heat exchanger 40, takes heat from the indoor air, and cools it. The vaporized low-pressure gas refrigerant flows into the indoor four-way valve 48 of the shunt controller 46. The indoor four-way valve 48 connects the high-pressure gas pipe port 48-1 and the low-pressure bypass pipe port 48-4, and connects the indoor heat exchanger side port 48-2 and the low-pressure gas pipe port 48-3. Yes. Therefore, the low-pressure gas refrigerant from the indoor heat exchanger 40 flows through the indoor four-way valve 48 to the indoor-side low-pressure gas branch pipe 7c, and then passes through the low-pressure gas pipe 7 that is the main pipe to the outdoor unit 1. Led.

In the shunt controller 46 of the indoor unit 3 that is in the cooling operation, the high-pressure gas refrigerant flows as follows. The high-pressure gas refrigerant that has flowed from the high-pressure gas pipe 5 through the high-pressure gas branch pipe 5c branched to each indoor unit 3 has the high-pressure gas branch pipe open / close valve 52 closed, so the high-pressure gas branch pipe bypass pipe 54 is closed. And the pressure is reduced by the first capillary tube 55. The decompressed gas refrigerant flows into the low-pressure bypass pipe 50 through the indoor four-way valve 48, is throttled by the second capillary tube 57 and adjusted in flow rate, and then joins the indoor-side low-pressure gas branch pipe 7c at the midway position 49. To do.
On the other hand, since the first high / low pressure bypass on / off valve 60 of the shunt controller 46 is closed, the high pressure gas refrigerant does not flow through the first high / low pressure bypass pipe 58.

  The low-pressure gas refrigerant flowing into the outdoor unit 1 through the low-pressure gas pipe 7 is returned to the compressor 10 a after gas-liquid separation by the accumulator 20.

  Moreover, as shown in FIG.5 (b), the shunt controller 46 of the indoor unit 3 which performs heating operation operate | moves as follows. The indoor four-way valve 48 of the shunt controller 46 allows the high-pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 to communicate with each other, and the low-pressure gas pipe port 48-3 and the low-pressure bypass pipe port 48-4. Is in communication. Therefore, the high-pressure gas refrigerant supplied from the high-pressure gas pipe 5 is led to the indoor heat exchanger 40 through the indoor four-way valve 48, and is condensed and liquefied by the indoor heat exchanger 40 to heat the indoor air. Give the heating. The high-pressure liquid refrigerant liquefied by the indoor heat exchanger 40 passes through the liquid refrigerant branch pipe 44 and joins the liquid pipe 9 that is the main pipe.

  Here, in the indoor unit 3 that performs the heating operation, by closing the first high / low pressure bypass on / off valve 60 of the flow dividing controller 46, the indoor unit 3 functions as a check valve and prevents the refrigerant from flowing back.

On the other hand, the following control is performed in the indoor unit 3c that includes the gas pipe pressure control kit 100 and is always in a cooling operation. FIG. 3B shows an example of an open / close pattern of the three solenoid valves 101a, 101b, 101c of the pressure control kit 100 used for the control. Here, in pattern 1 of the cooling operation, three solenoid valves 101a, 101b, and 101c are opened, in pattern 2, two solenoid valves 101a and 101b are opened, and in pattern 3, only one solenoid valve 101a is opened. Open.
That is, as shown in FIG. 6, after the operation of the indoor unit 3c is started (step S101), the temperature detected by the temperature sensor 33 provided in the indoor unit 3c is a specified temperature (eg, 3 ° C. in the example of FIG. 6). ) (Step S102). If the temperature is equal to or higher than the specified temperature, the cooling operation is set to pattern 1 (see FIG. 3B), and the three solenoid valves 101a, 101b, and 101c are set. Open (step S103).
On the other hand, when the detected temperature does not exceed the specified temperature in step S102, the cooling operation is set to pattern 2 (see FIG. 3B), the two electromagnetic valves 101a and 101b are opened, and the remaining electromagnetic valve 101c is closed ( Step S104).

Then, after a predetermined set timer time (for example, 120 seconds) has passed and the operation state has been stabilized, the temperature detected by the temperature sensor 33 provided in the indoor unit 3c is a specified temperature (for example, 3 ° C. in the example of FIG. 6). (Step S105), if the temperature is equal to or higher than the specified temperature, the cooling operation is set to pattern 2 (see FIG. 3B), and the two solenoid valves 101a and 101b are opened and remain. The state where the solenoid valve 101c is kept closed is maintained (step S106). On the other hand, when the detected temperature does not exceed the specified temperature in step S105, the cooling operation is set to pattern 3 (see FIG. 3B), and only one solenoid valve 101a is opened and the other solenoid valves 101b and 101c are opened. Close (step S107).
Such a series of processing is repeated every predetermined sampling time (for example, 120 seconds).

  Thus, the indoor unit 3c that is always operated for cooling includes the gas pipe pressure control kit 100 including a plurality of solenoid valves 101a, 101b, and 101c, and the solenoid valves 101a, 101b, and the like according to the refrigerant suction temperature. By controlling the opening and closing of 101c, the pressure loss of the refrigerant guided to the outdoor unit 1 through the low-temperature gas pipe 7 through the indoor heat exchanger 40 can be adjusted. Then, the evaporation pressure of the refrigerant in the indoor heat exchanger 40 can be adjusted. Thus, even when the outdoor temperature is low, the other indoor unit 3 performs the heating operation, and the outdoor unit 1 functions as an evaporator, the indoor unit 3c that performs the cooling operation does not perform suction. The temperature can be prevented from becoming below freezing point, and the indoor heat exchanger 40 can be prevented from freezing. As a result, it is not necessary to interrupt the cooling operation and perform the ice-breaking operation, so that the cooling operation can be performed continuously, and the cooling capacity of the indoor unit 3c that always performs the cooling operation can be increased.

Further, such a gas pipe pressure control kit 100 is separate from the shunt controller 46, and the indoor unit 3c that is always operated for cooling is equipped with this gas pipe pressure control kit 100, and other indoor units are provided. A diversion controller 46 may be provided in the unit 3c. Although it is possible to make the shunt controller 46 have the function of the gas pipe pressure control kit 100, in that case, the cost increases depending on the number of the indoor unit units 3, but if necessary, the gas pipe pressure control is performed. Since it is only necessary to select whether the kit 100 or the shunt controller 46 is provided, the above effect can be obtained at low cost.
Furthermore, since it is used by hardware such as the gas pipe pressure control kit 100 or the shunt controller 46 depending on whether it is dedicated to cooling or combined with cooling and heating, rather than being controlled by software, it depends on the individual air conditioning system. There is no need to set software, installation is easy, and costs can be reduced in this respect as well.

  In the above embodiment, the gas pipe pressure control kit 100 is configured to include the three solenoid valves 101a, 101b, and 101c. However, the gas pipe pressure control kit 100 includes two or four or more solenoid valves. You may do it.

[Second Embodiment]
Next, a second embodiment of the multi-type air conditioning system according to the present invention will be described. Here, in this embodiment, instead of the shunt controller 46 and the gas pipe pressure control kit 100 shown in the first embodiment, the shunt controller (cooling / heating operation switching mechanism) shown below is used for all indoor unit units. The point provided with 120 differs from said 1st embodiment. And about the outdoor unit 1 and the indoor unit 3, since it is a structure common to said 1st embodiment, it demonstrates centering on difference with said 1st embodiment, and about a common structure The description is omitted.

  As shown in FIG. 7, in this embodiment, the diversion controller 120 included in all the indoor unit units 3 includes an indoor four-way valve 48. The indoor four-way valve 48 includes a high-pressure gas pipe port 48-1 connected to the high-pressure gas branch pipe 5c branched from the main pipe of the high-pressure gas pipe 5, and an indoor heat exchanger-side port connected to the indoor heat exchanger 40 side. 48-2, a low-pressure gas pipe port 48-3 connected to the indoor-side low-pressure gas branch pipe 7c branched from the main pipe of the low-pressure gas pipe 7, and a low-pressure joining the middle position 49 of the indoor-side low-pressure gas branch pipe 7c A low-pressure bypass pipe port 48-4 connected to the bypass pipe 50.

  In such a shunt controller 120, the open / close state of the indoor four-way valve 48, the high pressure gas branch pipe on / off valve 52, the first high / low pressure bypass on / off valve 60, and the second high / low pressure bypass on / off valve 64 during the cooling operation and the heating operation. The setting example is the same as that shown in FIG.

  As shown in FIG. 8 (a), the indoor four-way valve 48 allows the high-pressure gas pipe port 48-1 and the low-pressure bypass pipe port 48-4 to communicate with each other and the indoor heat exchanger side port 48- during the cooling operation. 2 communicates with the low pressure gas pipe port 48-3. Further, as shown in FIG. 8B, the indoor four-way valve 48 communicates the high-pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 during heating operation, and the low-pressure gas pipe port. 48-3 communicates with the low pressure bypass pipe port 48-4.

  The high-pressure gas branch pipe 5 c on the upstream side of the indoor four-way valve 48 is provided with a high-pressure gas branch pipe on-off valve (first on-off valve) 52. A high-pressure gas branch pipe bypass pipe (high-pressure bypass pipe) 54 is formed so as to bypass the high-pressure gas branch pipe on-off valve 52, and a first capillary tube 55 is provided in the high-pressure gas branch pipe bypass pipe 54. Yes. One end of the high-pressure gas branch pipe bypass pipe 54 is connected to the upstream side of the high-pressure gas branch pipe 5c from the high-pressure gas branch pipe on-off valve 52, and the other end is connected to the downstream side of the high-pressure gas branch pipe on-off valve 52 from the high-pressure gas branch pipe on-off valve 52c. The end is connected to bypass the on-off valve 52 for the high-pressure gas branch pipe.

  A second capillary tube 57 is provided in the low pressure bypass pipe 50 on the downstream side of the indoor four-way valve 48.

  Between the high-pressure gas branch pipe 5c upstream of the high-pressure gas branch pipe bypass pipe 54 and the indoor low-pressure gas branch pipe 7c downstream of the low-pressure bypass pipe 50 (downstream of the midway position 49), A bypass pipe 58 is provided. The first high / low pressure bypass pipe 58 is provided with a first high / low pressure bypass opening / closing valve 60 and a third capillary tube 62 in order from the high pressure gas branch pipe 5c side toward the indoor side low pressure gas branch pipe 7c side. .

  One end is connected to the high-pressure gas branch pipe 5c between the downstream side of the high-pressure gas branch pipe bypass pipe 54 and the high-pressure gas pipe port 48-1 of the indoor four-way valve 48, and the downstream side of the low-pressure bypass pipe 50 (at the midway position 49). A second high / low pressure bypass pipe (high / low pressure bypass pipe) 63 whose other end is connected to the indoor side low pressure gas branch pipe 7c on the downstream side is provided. The second high / low pressure bypass pipe 63 includes a second high / low pressure bypass open / close valve (second open / close valve) 64 and a fourth capillary tube 65 from the high pressure gas branch pipe 5c side toward the indoor side low pressure gas branch pipe 7c side. Are provided in order.

A supercooling heat exchanger 121 is provided between the indoor side low-pressure gas branch pipe 7 c and the liquid pipe 9. As the supercooling heat exchanger 121, a general double pipe heat exchanger combining two copper pipes having different diameters or a plate heat exchanger can be used.
In such a shunt controller 120, the supercooling heat exchanger 121 is provided to bring the refrigerant into a supercooled state in the liquid pipe 9 during cooling.
Further, the shunt controller 120 is provided with a temperature sensor 123 on the outlet side of the supercooling heat exchanger 121 in the indoor-side low-pressure gas branch pipe 7c.

The indoor control device CL2 controls the shunt controller 120 in the same manner as shown in the first embodiment during the heating operation. At this time, the opening degree of the indoor expansion valve 42 of the indoor unit 3 is controlled based on the temperature difference between the temperature sensors 33 and 35.
That is, the heating degree SH (heat exchange at the outlet of the indoor heat exchanger 40, which is the difference between the detected temperature of the temperature sensor 35 on the inlet side of the indoor heat exchanger 40 and the detected temperature of the temperature sensor 33 on the outlet side during heating. The opening degree of the indoor expansion valve 42 is controlled such that the outlet SH = (the detected temperature of the temperature sensor 35) − (the detected temperature of the temperature sensor 33)) becomes a predetermined temperature.

  On the other hand, during cooling, from the difference between the temperature detected by the temperature sensor 123 on the outlet side of the supercooling heat exchanger 121 and the temperature detected by the temperature sensor 33 on the inlet side of the indoor heat exchanger 40 or the temperature sensor 35 on the outlet side. The required SH at the outlet of the shunt controller 120 (the shunt controller outlet SH = (the detected temperature of the temperature sensor 123) − (the lower one of the detected temperature of the temperature sensor 33 or the temperature sensor 35)) is a predetermined specified temperature. Thus, the opening degree of the indoor expansion valve 42 is controlled.

  FIG. 9 shows a control flow for switching the opening adjustment control of the indoor expansion valve 42 during such heating operation and cooling operation. After the operation starts, the indoor unit 3 is in the cooling operation. When the heating operation is performed (step S201), in the case of the heating operation, the opening adjustment control of the indoor expansion valve 42 is performed by the heat exchanger outlet SH (step S202), and the cooling operation is performed. In step S203, the degree of opening adjustment of the indoor expansion valve 42 is controlled by the shunt controller outlet SH.

In this way, in the shunt controller 120, during the cooling operation, the supercooling heat exchanger 121 causes the refrigerant in the liquid pipe 9 to be in a supercooled state, thereby sending the liquid refrigerant having a low enthalpy to the indoor unit 3. be able to.
Thereby, in the indoor unit 3, sufficient cooling capacity can be exhibited while ensuring the amount of refrigerant circulation.
Moreover, it can prevent that a liquid refrigerant returns to the compressor 10 through the liquid pipe 9, thereby preventing a failure of the compressor 10 and improving system reliability.

[Third embodiment]
Next, a third embodiment of the multi-type air conditioning system according to the present invention will be described. Here, in this embodiment, instead of the shunt controller 46 and the gas pipe pressure control kit 100 shown in the first embodiment, the shunt controller (cooling / heating operation switching mechanism) shown below is used for all indoor unit units. The point provided with 130 differs from said 1st embodiment. And about the outdoor unit 1 and the indoor unit 3, since it is a structure common to said 1st embodiment, it demonstrates centering on difference with said 1st embodiment, and about a common structure The description is omitted.

  As shown in FIG. 10, in this embodiment, the diversion controller 130 included in all the indoor unit units 3 includes an indoor four-way valve 48. The indoor four-way valve 48 includes a high-pressure gas pipe port 48-1 connected to the high-pressure gas branch pipe 5c branched from the main pipe of the high-pressure gas pipe 5, and an indoor heat exchanger-side port connected to the indoor heat exchanger 40 side. 48-2, a low-pressure gas pipe port 48-3 connected to the indoor-side low-pressure gas branch pipe 7c branched from the main pipe of the low-pressure gas pipe 7, and a low-pressure joining the middle position 49 of the indoor-side low-pressure gas branch pipe 7c A low-pressure bypass pipe port 48-4 connected to the bypass pipe 50.

  In such a shunt controller 120, the open / close state of the indoor four-way valve 48, the high pressure gas branch pipe on / off valve 52, the first high / low pressure bypass on / off valve 60, and the second high / low pressure bypass on / off valve 64 during the cooling operation and the heating operation. The setting example is the same as that shown in FIG.

  As shown in FIG. 11A, the indoor four-way valve 48 communicates the high-pressure gas pipe port 48-1 and the low-pressure bypass pipe port 48-4 during cooling operation, and the indoor heat exchanger side port 48- 2 communicates with the low pressure gas pipe port 48-3. Moreover, as shown in FIG.11 (b), the indoor four-way valve 48 connects the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 at the time of heating operation, and is a low pressure gas pipe port. 48-3 communicates with the low pressure bypass pipe port 48-4.

The high-pressure gas branch pipe 5 c on the upstream side of the indoor four-way valve 48 is provided with a high-pressure gas branch pipe on-off valve (first on-off valve) 52. In the diversion controller 130, the high-pressure gas branch pipe bypass pipe 54 and the first capillary tube 55 are not provided.
A second capillary tube 57 is provided in the low pressure bypass pipe 50 on the downstream side of the indoor four-way valve 48.

  Between the high-pressure gas branch pipe 5c upstream of the high-pressure gas branch pipe bypass pipe 54 and the indoor low-pressure gas branch pipe 7c downstream of the low-pressure bypass pipe 50 (downstream of the midway position 49), A bypass pipe 58 is provided. The first high / low pressure bypass pipe 58 is provided with a first high / low pressure bypass opening / closing valve 60 and a third capillary tube 62 in order from the high pressure gas branch pipe 5c side toward the indoor side low pressure gas branch pipe 7c side. .

  One end is connected to the high-pressure gas branch pipe 5c between the downstream side of the high-pressure gas branch pipe bypass pipe 54 and the high-pressure gas pipe port 48-1 of the indoor four-way valve 48, and the downstream side of the low-pressure bypass pipe 50 (at the midway position 49). A second high / low pressure bypass pipe (high / low pressure bypass pipe) 63 whose other end is connected to the indoor side low pressure gas branch pipe 7c on the downstream side is provided. The second high / low pressure bypass pipe 63 includes a second high / low pressure bypass open / close valve (second open / close valve) 64 and a fourth capillary tube 65 from the high pressure gas branch pipe 5c side toward the indoor side low pressure gas branch pipe 7c side. Are provided in order.

An overheat heat exchanger 131 is provided between the middle position 49 of the indoor low-pressure gas branch pipe 7 c and the second high-low pressure bypass pipe 63. As the superheat heat exchanger 131, a general double pipe heat exchanger combining two copper pipes having different diameters or a plate heat exchanger can be used.
In such a shunt controller 130, the superheat heat exchanger 131 is provided to bring the refrigerant into a superheated state in the liquid pipe 9 during cooling.
Further, the shunt controller 130 is provided with a temperature sensor 133 on the outlet side of the superheat heat exchanger 131 in the indoor-side low-pressure gas branch pipe 7c.

The indoor control device CL2 controls the shunt controller 130 in the same manner as shown in the first embodiment during the heating operation. At this time, the opening degree of the indoor expansion valve 42 of the indoor unit 3 is controlled based on the temperature difference between the temperature sensors 33 and 35.
That is, the heating degree SH (heat exchange at the outlet of the indoor heat exchanger 40, which is the difference between the detected temperature of the temperature sensor 35 on the inlet side of the indoor heat exchanger 40 and the detected temperature of the temperature sensor 33 on the outlet side during heating. The opening degree of the indoor expansion valve 42 is controlled such that the outlet SH = (the detected temperature of the temperature sensor 35) − (the detected temperature of the temperature sensor 33)) becomes a predetermined temperature.

  On the other hand, during cooling, it is obtained from the difference between the temperature detected by the temperature sensor 133 on the outlet side of the superheat exchanger 131 and the temperature detected by the temperature sensor 33 on the inlet side or the temperature sensor 35 on the outlet side of the indoor heat exchanger 40. SH at the outlet of the shunt controller 130 (the shunt controller outlet SH = (the detected temperature of the temperature sensor 133) − (the lower one of the detected temperature of the temperature sensor 33 or the temperature sensor 35)) is a predetermined specified temperature and Thus, the opening degree of the indoor expansion valve 42 is controlled.

  FIG. 9 shows a control flow for switching the opening adjustment control of the indoor expansion valve 42 during such heating operation and cooling operation. After the operation starts, the indoor unit 3 is in the cooling operation. When the heating operation is performed (step S201), in the case of the heating operation, the opening adjustment control of the indoor expansion valve 42 is performed by the heat exchanger outlet SH (step S202), and the cooling operation is performed. In step S203, the degree of opening adjustment of the indoor expansion valve 42 is controlled by the shunt controller outlet SH.

  In this way, in the shunt controller 130, during the cooling operation, the high-temperature and high-pressure liquid refrigerant condensed in the indoor heat exchanger 40 is superheated by the superheat heat exchanger 131, so that the low-pressure gas pipe side is positively heated. Can be shed. At this time, even if the liquid phase remains in the refrigerant, the unevaporated portion of the liquid refrigerant can be evaporated by heat exchange in the superheat heat exchanger 131. As a result, the amount of refrigerant flowing from the indoor heat exchanger 40 to the indoor side low-pressure gas branch pipe 7c can be increased, and even if the amount of refrigerant is increased, the unevaporated liquid refrigerant can be reliably evaporated. The compressor 10 can be prevented from being broken. Thereby, in the indoor unit 3, sufficient cooling capacity can be exhibited while ensuring the amount of refrigerant circulation.

  Furthermore, since the superheat heat exchanger 131 becomes a pressure loss and the evaporation temperature of the refrigerant in the indoor heat exchanger 40 increases, the indoor heat exchanger 40 is less likely to freeze. As a result, it is not necessary to interrupt the cooling operation and perform the ice-breaking operation, so that the cooling operation can be performed continuously, and the cooling capacity of the indoor unit 3 that always performs the cooling operation can be increased.

  Although the present invention has been described based on the embodiments, the present invention is not limited to the described embodiments, and modifications can be made without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Outdoor unit, 3 ... Indoor unit, 5 ... High pressure gas pipe (main pipe), 5c ... High pressure gas branch pipe, 7 ... Low pressure gas pipe (main pipe), 7c ... Indoor low pressure gas branch pipe, 9 ... Liquid pipe DESCRIPTION OF SYMBOLS 10 ... Compressor, 20 ... Accumulator, 23 ... Receiver, 25 ... Subcooler, 33, 35 ... Temperature sensor, 40 ... Indoor heat exchanger, 42 ... Indoor expansion valve, 44 ... Branch pipe for liquid refrigerant, 46 ... Shunt controller (cooling / heating operation switching mechanism), 48 ... indoor four-way valve, 48-1 ... high pressure gas pipe port (first port), 48-2 ... indoor heat exchanger side port (second port), 48-3 ... low pressure Gas pipe port (third port), 48-4 ... Low pressure bypass pipe port (4th port), 49 ... Midway position, 50 ... Low pressure bypass pipe, 52 ... High pressure gas branch pipe on / off valve (first on / off valve), 54 ... Bypass pipe for high pressure gas branch pipe (high pressure (Ipass pipe), 58 ... high / low pressure bypass pipe, 60 ... high / low pressure bypass on / off valve, 63 ... second high / low pressure bypass pipe (high / low pressure bypass pipe), 64 ... high / low pressure bypass on / off valve (second on / off valve), 70, DESCRIPTION OF SYMBOLS 80 ... Control part, 100 ... Gas pipe pressure control kit (evaporation pressure adjustment mechanism), 101a, 101b, 101c ... Solenoid valve (valve), 120 ... Shunt controller (cooling / heating operation switching mechanism), 102a, 102b, 102c ... Branch pipe 121 ... Supercooling heat exchanger, 130 ... Shunt controller (cooling / heating operation switching mechanism), 131 ... Superheat heat exchanger, 200 ... Multi-type air conditioning system

Claims (4)

A multi-type air conditioning system comprising an outdoor unit and an indoor unit in which a plurality of units are connected in parallel to the outdoor unit,
The outdoor unit is provided with a compressor and an outdoor heat exchanger that exchanges heat between the outside air and the refrigerant, and is connected to a discharge side of the compressor to supply a refrigerant in a high-pressure gas state. A high-pressure gas pipe, a low-pressure gas pipe connected to the suction side of the compressor and supplying a refrigerant in a gas state lower than the high-pressure gas pipe, and a liquid pipe supplying a liquid refrigerant And
The plurality of indoor unit units include an indoor heat exchanger that performs heat exchange between indoor air and the refrigerant,
At least one of the indoor unit units is dedicated to cooling, and includes an evaporation pressure adjusting mechanism that adjusts an evaporation pressure in the indoor heat exchanger for exchanging heat of the refrigerant supplied from the liquid pipe.
The remainder of the plurality of indoor unit units includes a cooling / heating operation switching mechanism that selectively switches between a cooling operation and a heating operation by switching the flow direction of the refrigerant in the high-pressure gas pipe, the low-pressure gas pipe, and the liquid pipe. As well as
The evaporating pressure adjusting mechanism branches the low-pressure gas pipe into a plurality of branch pipes between the indoor heat exchanger and the outdoor unit, and provides an openable and closable valve in each of the branch pipes. By adjusting the opening and closing of the valve, the evaporation pressure of the refrigerant in the indoor heat exchanger is adjusted, and
At least one of the indoor unit units supplies the refrigerant supplied from the liquid pipe to the indoor heat exchanger during the cooling operation to the cooling / heating operation switching mechanism, and the refrigerant and heat that has passed through the indoor heat exchanger. It is equipped with a supercooling heat exchanger that supercools by replacing it,
The indoor unit with the supercooling heat exchanger is
An expansion valve for adjusting the flow rate of the refrigerant passing through the indoor heat exchanger;
During the heating operation, the opening of the expansion valve is adjusted so that the temperature difference between the refrigerant on the inlet side and the outlet side of the indoor heat exchanger becomes a predetermined value, and during the cooling operation, A control unit that adjusts the opening of the expansion valve so that the temperature difference between the refrigerant on the outlet side and the inlet side of the supercooling heat exchanger becomes a predetermined specified value;
A multi-type air conditioning system comprising: The air-conditioning operation switching mechanism is
A first port connected to the high-pressure gas branch pipe branched from the main pipe of the high-pressure gas pipe; a second port connected to the indoor heat exchanger side; and a low-pressure gas branched from the main pipe of the low-pressure gas pipe A four-way valve formed with a third port connected to the branch pipe and a fourth port connected to the low-pressure bypass pipe joining the low-pressure gas branch pipe;
A first on-off valve provided on the high-pressure gas branch pipe upstream of the four-way valve;
One end is connected to the upstream side of the high-pressure gas branch pipe from the first on-off valve, and the other end is connected to the downstream side of the high-pressure gas branch pipe from the first on-off valve, bypassing the first on-off valve A high-pressure bypass pipe,
One end of the high-pressure gas branch pipe between the downstream side of the high-pressure bypass pipe and the first port of the four-way valve is connected, and the low-pressure gas branch pipe downstream from the position where the low-pressure bypass pipe is connected. A high and low pressure bypass pipe with the other end connected to
A second on-off valve provided on the high / low pressure bypass pipe;
The multi-type air conditioning system according to claim 1, comprising: A multi-type air conditioning system comprising an outdoor unit and an indoor unit in which a plurality of units are connected in parallel to the outdoor unit,
The outdoor unit is provided with a compressor and an outdoor heat exchanger that exchanges heat between the outside air and the refrigerant, and is connected to a discharge side of the compressor to supply a refrigerant in a high-pressure gas state. A high-pressure gas pipe, a low-pressure gas pipe connected to the suction side of the compressor and supplying a refrigerant in a gas state lower than the high-pressure gas pipe, and a liquid pipe supplying a liquid refrigerant And
The plurality of indoor unit units include an indoor heat exchanger that performs heat exchange between indoor air and the refrigerant,
The plurality of indoor unit units includes a cooling / heating operation switching mechanism that selectively switches between a cooling operation and a heating operation by switching a flow direction of the refrigerant in the high-pressure gas pipe, the low-pressure gas pipe, and the liquid pipe,
At least one of the indoor unit units includes the refrigerant that is sent to the low-pressure gas pipe through the indoor heat exchanger and the refrigerant that is sent from the high-pressure gas pipe to the air-conditioning operation switching mechanism during the cooling operation. A multi-type air conditioning system comprising an overheat heat exchanger that heats by heat exchange. The indoor unit provided with the superheat exchanger is,
An expansion valve for adjusting the flow rate of the refrigerant passing through the indoor heat exchanger;
During the heating operation, the opening of the expansion valve is adjusted so that the temperature difference between the refrigerant on the inlet side and the outlet side of the indoor heat exchanger becomes a predetermined value, and during the cooling operation, A control unit that adjusts the opening of the expansion valve so that the temperature difference between the refrigerant on the outlet side and the inlet side of the superheat heat exchanger becomes a predetermined specified value;
The multi-type air conditioning system according to claim 3, comprising:

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