JP2006125762A - Indoor unit, air conditioning device comprising the same, and its operating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an indoor unit, an air conditioning device comprising the same, and its operating method capable of efficiently and easily recovering oil in a high-pressure gas pipe. <P>SOLUTION: This indoor unit of an air conditioning device which comprises an indoor heat exchanger 40 connected with an outdoor unit 1 by a low-pressure gas pipe 7, the high-pressure gas pipe 5 and a liquid pipe 9, and to which a refrigerant is supplied from the high-pressure gas pipe 5 or the liquid pipe 9 to exchange the heat with the indoor air, further comprises a high/low pressure bypass pipe 58 connecting a high-pressure gas branch pipe 5c and a low-pressure gas branch pipe 7c and bypassing the indoor heat exchanger 40, and the high/low pressure bypass pipe 58 is provided with an opening and closing valve 60 for the high/low pressure bypass pipe. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an indoor unit connected to an outdoor unit by a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, and an air conditioner including the indoor unit.

A so-called air conditioning free multi-air conditioner is provided as an air conditioner that includes a plurality of indoor units connected to one outdoor unit by a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe, and independently performs cooling and heating operations in each indoor unit. It is known (see Patent Document 1).
FIG. 13 shows such an air conditioning free multi air conditioner.
The outdoor unit 100 is provided with a compressor 101 that compresses the refrigerant and two outdoor heat exchangers 103A and 103B. The outdoor heat exchangers 103A and 103B are provided with outdoor switching valves 102A and 102B, respectively, for selectively switching the connection between the high pressure gas pipe 110 and the low pressure gas pipe 111.
The high pressure gas pipe 110 is a flow path through which discharge gas from the compressor 101 is guided, and the low pressure gas pipe 111 is a flow path through which low pressure gas from the indoor units A, B, and C is guided.
A liquid pipe 112 is connected to the end of the outdoor heat exchanger 103A, B that is opposite to the outdoor switching valve 102A, B.

  Each of the indoor units A, B, and C includes indoor heat exchangers 107A, B, and C, and each of the indoor heat exchangers 107A, B, and C includes the outdoor unit 100, the high pressure gas pipe 110, and the low pressure gas pipe 111. And a liquid pipe 112. Each indoor heat exchanger 107A, B, C is provided with indoor side switching valves 108A, B, C to selectively switch the connection between the high pressure gas pipe 110 and the low pressure gas pipe 111. . Each indoor heat exchanger 107A, B, C is provided with expansion valves 106A, B, C for expanding the liquid refrigerant from the liquid pipe 112.

The air conditioning free multi air conditioner having the above configuration is operated as follows.
As an example, an operation in which the indoor units A and B are cooled and the indoor unit C is heated will be described.
The refrigerant compressed by the compressor 101 is led to the high-pressure gas pipe 110, and the high-pressure gas pipe 110 is selected by the outdoor switching valve 102B and led to the outdoor heat exchanger 103B.
The other outdoor heat exchanger 103A guides high-pressure gas from the outdoor switching valve 102A, passes through the check valve 105A and the capillary tube 135, and reduces the pressure to the liquid pipe 112 in order to prevent liquid refrigerant from accumulating. Lead.
The liquid refrigerant condensed and liquefied after passing through the outdoor heat exchanger 103A operating as a condenser is guided to the indoor units A and B through the liquid pipe 112 and expanded by the expansion valves 106A and B, and then the indoor heat exchanger 107A. , B evaporates to cool the room air. Thereby, the indoor units A and B perform a cooling operation. The refrigerant that has passed through the indoor heat exchangers 107A, B is guided to the low-pressure gas pipe 111 selected by the indoor side switching valves 108A, B, passes through the accumulator 114, and is returned to the compressor 101 again.
The indoor side switching valve 108C of the indoor unit C selects the high-pressure gas pipe 110, and the high-pressure gas is guided to the indoor heat exchanger 107C to warm the indoor air. The refrigerant that is condensed and liquefied by warming the indoor air is guided to the liquid pipe 112.

Japanese Patent Laid-Open No. 9-310931 ([0017] to [0021], FIG. 1)

  Generally, the compressor of an air conditioner uses lubricating oil for lubrication of the sliding part. As this lubricating oil, an oil having a property of being dissolved in a refrigerant is used. A part of the lubricating oil flows in a system such as an indoor heat exchanger or an outdoor heat exchanger together with the refrigerant discharged from the compressor, and is recovered again by the compressor. It is like that. When this lubricating oil flows through the system, if it adheres to the inner wall of the heat exchanger, heat transfer will be hindered. Furthermore, when the lubricating oil adheres to the inner wall of the refrigerant pipe, the amount of lubricating oil returned to the compressor is reduced, leading to insufficient lubrication of the compressor. Therefore, in order to recover the lubricating oil that has adhered to and stayed on the inner wall of the heat exchanger or the refrigerant pipe, an oil return operation for recovering the lubricating oil is performed on the compressor side.

In the conventional air conditioning free multi-air conditioner described above, liquid refrigerant flows through the liquid pipe 112, and oil is recovered together with the liquid refrigerant. Therefore, the oil return operation is not particularly required.
For the low-pressure gas pipe 111, during cooling, the number of revolutions of the compressor 101 is increased to increase the gas refrigerant flow rate in the system, and the refrigerant flows out from the indoor heat exchangers 107A, B, and C as liquid. The oil return operation is performed by flowing the liquid refrigerant into the low-pressure gas pipe (liquid back). During heating, the oil return operation is performed by temporarily switching to the cooling cycle and performing a pseudo defrost operation to cause liquid back.

However, the high-pressure gas pipe 110 is prepared to supply the high-pressure gas refrigerant to the indoor heat exchangers 107A, B, and C only at the time of heating, that is, a gas pipe dedicated to heating, and lubricating oil is piped. Easily stays inside.
Although oil recovery by liquid back operation is also conceivable, since the high-pressure gas pipe 110 is connected to the discharge side of the compressor 101, a configuration for switching the high-pressure gas pipe 110 to the suction side of the compressor 101 is newly required. This leads to cost increase and is not realistic.
In particular, in recent years, the piping length has become 1.5 times or more than before due to sophistication of market demand, making oil recovery more difficult.

  The present invention has been made in view of such circumstances, and provides an indoor unit that can efficiently and easily recover oil from a high-pressure gas pipe, an air conditioner including the indoor unit, and an operation method thereof. For the purpose.

In order to solve the above-described problems, the indoor unit of the present invention, an air conditioner including the indoor unit, and an operation method thereof employ the following means.
That is, the indoor unit of the air conditioner according to the present invention is connected to the outdoor unit by a low-pressure gas pipe, a high-pressure gas pipe, and a liquid pipe, and a refrigerant is supplied from the high-pressure gas pipe or the liquid pipe to exchange heat with room air. In an indoor unit of an air conditioner including an indoor heat exchanger that performs the above, a bypass pipe that connects the high-pressure gas pipe and the low-pressure gas pipe to bypass the indoor heat exchanger is provided, and the bypass pipe is opened and closed A valve is provided.

A bypass pipe that connects the high-pressure gas pipe and the low-pressure gas pipe to bypass the indoor heat exchanger is provided in the indoor unit, and the on-off valve of the bypass pipe is opened, so that the refrigerant is transferred from the high-pressure gas pipe to the low-pressure gas pipe. Flows. In this way, a gas refrigerant flow from the high-pressure gas pipe to the low-pressure gas pipe is formed, and the oil return operation for recovering oil adhering to the inner walls of the high-pressure gas pipe and the low-pressure gas pipe is possible using the flow rate of this gas refrigerant. It becomes.
In particular, since the indoor heat exchanger is bypassed and the high-pressure gas pipe and the low-pressure gas pipe are connected, the gas refrigerant can always flow at a high flow rate regardless of the usage conditions of the unit. Oil return can be performed.
Further, since the indoor heat exchanger is bypassed so that the gas refrigerant does not pass through the indoor heat exchanger, noise during the oil return operation is not transmitted to the room.
In addition, since a gas refrigerant flow that sequentially flows through the high-pressure gas pipe, the bypass pipe, and the low-pressure gas pipe is formed, the high-pressure gas pipe and the low-pressure gas pipe can be oil-returned simultaneously, Can be recovered in a short time.

  Furthermore, the indoor unit of the air conditioner according to the present invention is characterized in that the bypass pipe is provided with noise prevention means for preventing noise caused by the refrigerant flowing in the bypass pipe.

Since the high-pressure gas pipe and the low-pressure gas pipe are connected, the gas refrigerant flows with a large pressure difference, and the deceleration of the gas refrigerant flowing in the bypass pipe becomes too large, which may cause noise. By providing the bypass pipe with noise prevention means, noise of the bypass pipe is prevented.
Examples of the noise preventing means include a fixing means for rigidly fixing the bypass pipe.

  Furthermore, the indoor unit of the air conditioner of the present invention is characterized in that a speed reduction means provided in the bypass pipe is used as the noise prevention means.

The speed of the refrigerant flowing in the bypass flow path is adjusted by the speed reduction means, thereby suppressing the generation of noise.
As the speed reduction means, a capillary tube is suitable.

  In addition, the air conditioner of the present invention is connected to the outdoor unit by a low pressure gas pipe, a high pressure gas pipe, and a liquid pipe, and an outdoor unit provided with a compressor that compresses the refrigerant and an outdoor heat exchanger that exchanges heat with the outside air. A plurality of indoor units including an indoor heat exchanger that is supplied with a refrigerant from the high-pressure gas pipe or the liquid pipe and exchanges heat with the indoor air. It is characterized by having at least one.

  In addition, the operation method of the air conditioner of the present invention includes an outdoor unit including a compressor that compresses a refrigerant and an outdoor heat exchanger that performs heat exchange with outside air, and a low-pressure gas pipe, a high-pressure gas pipe, and a liquid pipe. A plurality of indoor units including an indoor heat exchanger that is connected to a unit and is supplied with a refrigerant from the high-pressure gas pipe or the liquid pipe and performs heat exchange with the indoor air. An oil return operation is performed in which an indoor heat exchanger is bypassed and a gas refrigerant is allowed to flow between the high-pressure gas pipe and the low-pressure gas pipe.

  Since a bypass pipe is provided between the high-pressure gas pipe and the low-pressure gas pipe and the gas refrigerant is allowed to flow through the bypass pipe, oil can be efficiently recovered with a simple configuration.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic configuration of an air conditioning free multi-air conditioner (air conditioner).
The air conditioning free multi-air conditioner includes one outdoor unit (outdoor unit) 1, a plurality of indoor units (indoor units) 3, and a high pressure gas pipe 5, a low pressure gas pipe 7, and a liquid pipe 9 that connect them. .
The outdoor unit 1 includes, for example, two compressors 10 and, for example, two outdoor heat exchangers 12.
The outdoor heat exchanger 12 exchanges heat with outdoor air, and operates as a condenser or an evaporator depending on the state of the refrigerant passing therethrough. Outdoor expansion valves 13a and 13b are provided between the outdoor heat exchangers 12a and 12b and the liquid pipes 9 between the receivers 23 and in the vicinity of the outdoor heat exchangers 12a and 12b, respectively. ing. Outdoor expansion valve bypass pipes 16a and 16b that bypass the outdoor expansion valves 13a and 13b are provided, and the refrigerant flow from the outdoor heat exchangers 12a and 12b to the receiver 23 is supplied to each of the bypass pipes 16a and 16b. Check valves 19a and 19b are provided to allow and prevent reverse flow. An open / close valve 21 is provided on the upstream side of the check valve 19a in the outdoor expansion valve bypass pipe 16a connected to the first outdoor heat exchanger 12a.
The pipes connected to the receiver 23 side of the outdoor expansion valves 13 a and 13 b are joined at the junction 9 a of the liquid pipe 9.

Each compressor 10a, b is preferably a scroll compressor. Two of these compressors 10a and 10b may be operated simultaneously depending on the required capacity, or only one unit may be operated and the other unit may be used as a backup.
The refrigerant compressed by the compressor 10 becomes a high-pressure gas refrigerant and is discharged to the high-pressure gas pipe 5.
For example, R401A is used as the refrigerant. This R401A has a density about 1.4 times (5 ° C) compared to the conventional refrigerants R22 and R407C, and is a high-pressure and high-pressure refrigerant 1.6 times higher pressure (5 ° C), so it exhibits high refrigerating capacity. In addition, the pressure loss is small.

  The high-pressure gas pipe 5 positioned 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 a low pressure gas branch pipe 15a and a low pressure gas branch pipe 15a branched at a branch point 7d of the low pressure gas pipe 7, respectively. a low pressure gas pipe side port 14-3 connected to b, and a bypass pipe side port 14-4 connected to the low pressure gas branch pipes 15a, 15b via strainers 17a, b and capillary tubes 18a, b. Yes.

  The low-pressure gas pipe 7 located in the outdoor unit 1 is connected to the compressors 10 a and 10 b via the accumulator 20. The liquid refrigerant collected in the accumulator 20 is returned to the compressors 10a and 10b by liquid refrigerant return lines 22a and 22b.

  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 side four-way valves 14a and 14b. The liquid pipe 9 in the outdoor unit 1 includes a receiver 23 that stores the liquid refrigerant and a supercooler 25 that supercools the refrigerant that flows 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 units 3 are provided, and the configuration of each indoor unit is the same.
The indoor unit 3 includes an indoor heat exchanger 40 that exchanges heat with room air. An expansion valve 42 is provided in the liquid refrigerant branch pipe 44 that connects the indoor heat exchanger 40 and the liquid pipe 9.
Each indoor unit 3 is provided with a shunt controller 46 for switching between the high pressure gas pipe 5 and the low pressure gas pipe 7.

The shunt controller 46 has the following configuration.
The shunt controller 46 includes an indoor four-way valve 48. The indoor-side 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 the indoor heat exchanger side connected to the indoor heat exchanger 40 side. The port 48-2, the 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 the midway position 49 of the indoor-side low-pressure gas branch pipe 7c merge. A low-pressure bypass pipe port 48-4 connected to the low-pressure bypass pipe 50.

  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. Communicate with. Further, the indoor side 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 and the low pressure gas pipe port 49. -3.

A high-pressure gas branch pipe open / close valve 52 is provided in the high-pressure gas branch pipe 5 c upstream of the indoor side four-way valve 48. A high-pressure gas branch pipe bypass passage 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 passage 54.
A second capillary tube 57 is provided in the low pressure bypass pipe 50 on the downstream side of the indoor side four-way valve 48.
There is a high-low pressure bypass between the high-pressure gas branch pipe 5c upstream of the high-pressure gas branch pipe bypass passage 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 pipe (bypass pipe) 58 is provided. The high / low pressure bypass pipe 58 includes a high / low pressure bypass pipe open / close valve (open / close valve) 60 and a third capillary tube (deceleration means) 62 from the high pressure gas branch pipe 5c side toward the indoor side low pressure gas branch pipe 7c side. It is provided in order.

Next, the operation of the cooling / heating free multi air conditioner having the above-described configuration will be described according to each operation mode.
Thereafter, an embodiment of the oil return operation according to the present invention will be described.
As will be described below, the air-conditioning / free multi-air conditioner according to the present embodiment appropriately changes the operation of the outdoor heat exchanger 12 according to the required condensation capacity / evaporation capacity.

[All cooling unit operation: Operation pattern C4]
First, the operation when the cooling operation is selected in all the indoor units 3 as in the summer will be described with reference to FIG. In this case, the two outdoor heat exchangers 12a and 12b operate as condensers.
The high-pressure gas refrigerant compressed by the compressor 10a branches at the branch points 5a and 5b of the high-pressure gas pipe 5 and flows to the outdoor four-way valves 14a and 14b. On the other hand, a part (very small amount) of the high-pressure gas refrigerant flows to the indoor unit 3 through the high-pressure gas pipe 5 connected to the indoor unit 3. In this embodiment, only one compressor is used, and the other one is used for backup.
In the outdoor four-way valves 14a and 14b, the high pressure gas pipe port 14-1 and the outdoor heat exchanger side port 14-2 are communicated, and the low pressure gas pipe side port 14-3 and the bypass pipe side port 14-4 are connected. It is communicated. Therefore, the high-pressure gas refrigerant flowing into the high-pressure gas pipe port 14-1 passes through the outdoor heat exchanger side port 14-2 and is guided to the outdoor heat exchangers 12a and 12b. On the other hand, the low pressure gas pipe side port 14-3 and the bypass pipe side port 14-4 of the outdoor four-way valves 14a and 14b communicate with each other, and the flow path passing through the outdoor low pressure gas branch 15a and b is a closed loop. Therefore, the high-pressure gas refrigerant does not flow into the outdoor low-pressure gas branch pipes 15a and 15b, and the low-pressure gas refrigerant does not flow from the branch point 7d of the low-pressure gas pipe 7. However, the inside of the outdoor low-pressure gas branch pipes 15a and 15b is in a state filled with the low-pressure gas refrigerant.

  The high-pressure gas refrigerant that has flowed into the outdoor heat exchangers 12a and 12b exchanges heat with the outside air to dissipate heat and is condensed and liquefied. The condensed and liquefied high-pressure liquid refrigerant passes through the receiver 23, is supercooled by the supercooler 25, and then is guided to the indoor unit 3 through the liquid pipe 9. Note that the liquid pipe 9 connecting the outdoor unit 1 and the indoor unit 3 has a length exceeding 100 m. Therefore, it is desirable to avoid evaporation of the liquid refrigerant in the liquid pipe 9 by supercooling in this way. .

  The high-pressure liquid refrigerant flowing into the indoor unit 3 is branched to the high-pressure gas branch pipe 5c connected to each indoor unit 3, and then is throttled and expanded by the expansion valve 42 of each indoor unit 3. 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 side four-way valve 48 of the shunt controller 46. The indoor side four-way valve 48 communicates the high pressure gas pipe port 48-1 and the low pressure bypass pipe port 48-4, and communicates the indoor heat exchanger side port 48-2 and the low pressure gas pipe port 49-3. ing. Therefore, the low-pressure gas refrigerant from the indoor heat exchanger 40 flows through the indoor-side 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, the following refrigerant flow is formed for the high-pressure gas refrigerant. 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 on-off valve 52 closed, so that the high-pressure gas branch pipe bypass passage 54 is closed. And the pressure is reduced by the first capillary tube 55. The decompressed gas refrigerant passes through the indoor side four-way valve 48 and flows into the low pressure bypass pipe 50, and is throttled by the second capillary tube 57 and the flow rate is adjusted, and then is passed to the indoor side low pressure gas branch pipe 7 c at the midway position 49. Join. As described above, since the high-pressure gas refrigerant in the high-pressure gas branch pipe 5c flows through the indoor four-way valve 48, the high-pressure gas does not stay in the high-pressure gas branch pipe 5c, and as a result, the high-pressure gas that is the main pipe High-pressure gas does not stay in the pipe 5. Therefore, the high-pressure gas refrigerant is prevented from radiating and condensing in the high-pressure gas pipe 5 (or high-pressure gas branch pipe 5 c), and liquid refrigerant is prevented from accumulating in the high-pressure gas pipe 5. In particular, the piping length of the high-pressure gas pipe 5 connecting the outdoor unit 1 and the indoor unit 3 exceeds 100 m, and even if the pipe is insulated, the amount of heat radiation cannot be ignored. The refrigerant circuit that is caused to flow by the diversion controller 46 is effective.
On the other hand, the high / low pressure bypass pipe on / off valve 60 of the branch controller 46 is closed, so that the high pressure gas refrigerant does not flow through the 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 the liquid refrigerant is removed by the accumulator 20.
Thus, in the all-cooling all-unit operation, since the required condensation capacity is large, the two outdoor heat exchangers 12a and 12b are operated as condensers.

[Cooling only operation (with stop unit): Operation pattern C4 ′]
As shown in FIG. 2, even in the cooling only operation, not only when the blower fans (not shown) of all the indoor units 3 are operating, but some units (in the figure, the indoor unit 3d ) The blower fan does not rotate and may be a stop unit. In this case, since the required condensation capacity is still large (for example, 100% of the capacity), both of the outdoor heat exchangers 12a and 12b operate as condensers.
Also in this operation pattern, the high / low pressure bypass pipe opening / closing valve 60 provided in the high / low pressure bypass pipe 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is closed.

[Cooling subject (cooling period): Operation pattern C4 "]
As shown in FIG. 3, even in the cooling period such as summer, one or a plurality of indoor units 3 (only the indoor unit 3a in the figure) may be selected for heating operation. In this case, since the required condensation capacity is still large (for example, 100% of the capacity), both of the outdoor heat exchangers 12a and 12b operate as condensers.
The indoor unit 3a is switched from the cooling operation to the heating operation by switching the indoor side four-way valve 48. That is, the indoor-side 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 and low-pressure gas pipe port 49. -3 communicated with each other during the heating operation, the high-pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2 are communicated, and the low-pressure gas pipe port 48-3 and the low-pressure bypass pipe It is switched to communicate with port 48-4.

Thereafter, the on-off valve 52 for the high-pressure gas branch pipe is opened. Immediately before the opening / closing valve 52 is opened, the high-pressure gas is reduced to a pressure close to that of the low-pressure gas by the first capillary tube 55 provided in the high-pressure gas branch pipe bypass passage 54. Therefore, the pressure close to the low pressure gas is applied to the high pressure gas pipe port 48-1. In this state, the indoor side four-way valve 48 is switched to connect the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2, so that the pressure difference at the time of switching can be made as small as possible. The noise at the time of switching of the indoor side four-way valve 48 can be prevented.
Thus, when the indoor side four-way valve 48 is switched, the high-pressure gas refrigerant is guided to the indoor heat exchanger 40, and is condensed and liquefied by the indoor heat exchanger 40 to give heat to the indoor air to heat it. Do. 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.

  Also in this operation pattern, the high / low pressure bypass pipe opening / closing valve 60 provided in the high / low pressure bypass pipe 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is closed.

[Cooling main (interim period: within outdoor fan control range): operation pattern C2]
FIG. 4 shows a case where the cooling-dominant operation is performed in an intermediate period such as spring or autumn in which the number of indoor units 3 that perform the cooling operation is larger than the number of indoor units 3 that perform the heating operation. ing. Also, the outdoor temperature is not too low as in winter (for example, 5 ° C. or higher), and the outdoor fan (not shown) provided in the outdoor heat exchangers 12a and 12b is operated or stopped (or the rotational speed of the outdoor fan is controlled). This is the case where the condensation capacity can be controlled.

In this operation pattern, since the required cooling capacity is not large as in the summer, and the required condensation capacity is relatively small (for example, 50% of the capacity), the second outdoor heat exchanger 12b is stopped. The stop of the second outdoor heat exchanger 12b is performed as follows.
By switching the outdoor four-way valve 14b connected to the second outdoor heat exchanger 12b, the communication between the high pressure gas pipe port 14-1 and the outdoor heat exchanger side port 14-2 is cut off, and the high pressure gas pipe port 14-1 is disconnected. And the bypass pipe side port 14-4 are communicated, and the outdoor heat exchanger side port 14-2 and the low pressure gas pipe side port 14-3 are communicated. This prevents the high-pressure gas discharged from the compressor 10a from flowing into the second outdoor heat exchanger 12b. Further, the outdoor expansion valve 13b connected to the second outdoor heat exchanger 12b is fully closed.

  The outdoor expansion valve 13a on the downstream side of the other first outdoor heat exchanger 12a is fully opened, and the on-off valve 21 provided in the outdoor expansion valve bypass pipe 16a is also opened.

The shunt controller 46 of the indoor unit 3a that performs the heating operation is operated as follows.
The indoor side four-way valve 48 of the shunt controller 46 communicates the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2, and the low pressure gas pipe port 48-3 and the low pressure bypass pipe port 48-4. And communicate with. Therefore, the high-pressure gas refrigerant is led to the indoor heat exchanger 40 through the indoor side four-way valve 48, and is condensed and liquefied by the indoor heat exchanger 40 to give heat to the indoor air to perform 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.

  Also in this operation pattern, the high / low pressure bypass pipe opening / closing valve 60 provided in the high / low pressure bypass pipe 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is closed.

[Cooling main (interim period: within outdoor fan control range): operation pattern C1]
FIG. 5 shows an operation pattern similar to the operation pattern C2 described with reference to FIG. The main operation pattern C1 and the operation pattern C2 differ in that the required condensation capacity is smaller in the main operation pattern C1 (for example, about 0 to 50% of the capacity). Therefore, in the operation pattern C2, both the outdoor expansion valve 13a and the on-off valve 21 of the outdoor expansion valve bypass pipe 16a arranged on the downstream side of the first outdoor heat exchanger 12a are fully opened. In the operation pattern C1, the outdoor expansion valve 13a is throttled stepwise to an intermediate opening, and the on-off valve 21 of the outdoor expansion valve bypass pipe 16a is fully closed. In this way, the condensing capacity exhibited in the outdoor unit 1 is adjusted.

  Also in this operation pattern, the high / low pressure bypass pipe opening / closing valve 60 provided in the high / low pressure bypass pipe 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is closed.

[Cooling / heating balance (cooling ≒ heating, low outside air temperature, small capacity): operation pattern C2 ']
FIG. 6 shows a cooling / heating balance operation in which the number of indoor units 3 performing the cooling operation is the same as the number of heating operations, and each indoor heat exchanger 40 is balanced with a small capacity, And the case where the outside temperature is low as in winter is shown.

In the figure, the heating operation is selected for the indoor units 3a and 3b, and the cooling operation is selected for the indoor units 3c and d. The operation of the diversion controller 46 during the heating operation and the cooling operation is as described above.
That is, the indoor side four-way valve 48 of the flow dividing controller 46 in which the heating operation is performed communicates the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2, and the low pressure gas pipe port 48-. 3 communicates with the low-pressure bypass pipe port 48-4.
The indoor side four-way valve 48 of the shunt controller 46 in which the cooling operation is performed communicates the high pressure gas pipe port 48-1 and the low pressure bypass pipe port 48-4, and the indoor heat exchanger side port 48-2. The low-pressure gas pipe port 49-3 is in communication.

In this operation pattern C2 ′, the first outdoor heat exchanger 12a is operated as a condenser and the second outdoor heat exchanger 12b is operated as an evaporator.
That is, the on-off valve 21 provided in the outdoor expansion valve 13a and the outdoor expansion valve bypass pipe 16a is opened, and the first outdoor heat exchanger 12a is operated as a condenser.
The outdoor heat exchanger side port 14-2 and the low pressure gas pipe side port 14-3 communicate with each other by the outdoor side four-way valve 14b connected to the second outdoor heat exchanger 12b. The high-pressure liquid refrigerant flows from 9a into the outdoor expansion valve 13b. The opening degree of the outdoor expansion valve 13b is adjusted so as to operate as a throttle valve. Here, the high-pressure liquid refrigerant is expanded and flows to the second outdoor heat exchanger 12b, and is evaporated by heat exchange with the outside air. It is supposed to be made. Thereby, the 2nd outdoor heat exchanger 12b is operated as an evaporator.

In this operation pattern C2 ′, when the compressor 10 is operated at a low pressure commensurate with the low outside air temperature, the frequency of the compressor increases to maintain the necessary high pressure, and the amount of refrigerant circulating in the system increases. End up. However, since each indoor heat exchanger 40 is balanced with a small capacity, there is a risk of losing the balance between the cooling and heating mixed operation when the refrigerant circulation amount increases.
Moreover, since it is set as the low outdoor temperature, if both outdoor heat exchangers 12a and 12b are stopped (these outdoor heat exchangers 12a and 12b are in the state of an evaporator in preparation for heating operation). ), The refrigerant may condense and accumulate in a large amount in the outdoor heat exchangers 12a and 12b.
Therefore, by operating the first outdoor heat exchanger 12a as a condenser and the second outdoor heat exchanger 12b as an evaporator, it is possible to always cause the refrigerant to flow in the outdoor heat exchangers 12a and 12b, Prevents accumulation of refrigerant. Further, since the refrigerant circulation amount can be increased, the necessary compressor frequency can be maintained.

  Also in this operation pattern, the high / low pressure bypass pipe opening / closing valve 60 provided in the high / low pressure bypass pipe 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is closed.

[Cooling / heating balance (cooling ≒ heating, low pressure allowable range): operation pattern C0]
FIG. 7 shows a cooling / heating balance operation in which the number of indoor units 3 performing the cooling operation and the number of performing the heating operation are equal. Unlike the operation pattern C2 ′ shown in FIG. 6, the main operation pattern C0 has a relatively large capacity of each indoor heat exchanger 40 that performs the heating operation of the indoor unit 3, and corresponds to the outside air temperature. Even when the saturated vapor pressure is taken into consideration, the liquid refrigerant is allowed to accumulate in the outdoor heat exchangers 12a and 12b (low pressure allowable range).
Therefore, in this operation pattern C0, both the outdoor heat exchangers 12a and 12b are stopped, that is, do not flow the refrigerant, and are not operated as a condenser or an evaporator. That is, the high pressure gas pipe port 14-1 and the bypass pipe side port 14-4 of the outdoor four-way valves 14a and 14b are communicated, and the outdoor heat exchanger side port 14-2 and the low pressure gas pipe side port 14-3 are connected. The communication is cut off between the high pressure gas pipe port 14-1 and the outdoor heat exchanger side port 14-2.
As the high-pressure liquid refrigerant used for the cooling operation, the high-pressure liquid refrigerant condensed in the indoor heat exchanger 40 of the indoor units 3a and 3b performing the heating operation is used.

Also in this operation pattern, the indoor side four-way valve 48 of the flow dividing controller 46 in which the heating operation is performed communicates the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2, and the low pressure gas. The pipe port 48-3 communicates with the low pressure bypass pipe port 48-4.
Further, the indoor side four-way valve 48 of the flow dividing controller 46 in which the cooling operation is performed communicates the high pressure gas pipe port 48-1 and the low pressure bypass pipe port 48-4, and the indoor heat exchanger side port 48-. 2 and a low-pressure gas pipe port 49-3.

  Also in this operation pattern, the high / low pressure bypass pipe opening / closing valve 60 provided in the high / low pressure bypass pipe 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is closed.

[All-heating all-unit operation: Operation pattern E4]
Next, the operation when the heating operation is selected in all the indoor units 3 as in winter will be described with reference to FIG. In this case, the two outdoor heat exchangers 12a and 12b operate as an evaporator.

  The high-pressure gas refrigerant compressed by the compressor 10 a is guided to the indoor unit 3 through the high-pressure gas pipe 5. A small part of the high-pressure gas refrigerant branches at the branch points 5a and b of the high-pressure gas pipe 5 and flows into the outdoor four-way valves 14a and 14b. The outdoor four-way valves 14a and 14b communicate with a high-pressure gas pipe port 14-1 and a bypass pipe-side port 14-4, and are connected to an outdoor heat exchanger-side port 14-2 and a low-pressure gas pipe-side port 14-3. Is communicated. Therefore, the high-pressure gas refrigerant that has flowed into the outdoor four-way valves 14a and 14b is depressurized by the capillary tubes 18a and 18b through the bypass pipe-side port 14-4, and then into the outdoor low-pressure gas branch pipes 15a and 15b. Join. The low-pressure gas refrigerant in the outdoor low-pressure gas branch pipes 15a and 15b passes through the accumulator 20 and is returned to the compressor 10a again. Further, the low-pressure gas refrigerant guided from the outdoor heat exchangers 12a and 12b also flows to the outdoor low-pressure gas branch pipes 15a and 15b via the outdoor four-way valves 14a and 14b.

  The high-pressure gas refrigerant guided to the indoor unit 3 by the high-pressure gas pipe 5 passes through each high-pressure gas branch pipe 5 c and flows into each branch controller 46. The indoor side four-way valve 48 of the shunt controller 46 communicates the high pressure gas pipe port 48-1 and the indoor heat exchanger side port 48-2, and the low pressure gas pipe port 48-3 and the low pressure bypass pipe port 48-4. And communicate with. Therefore, the high-pressure gas refrigerant is led to the indoor heat exchanger 40 through the indoor side four-way valve 48, and is condensed and liquefied by the indoor heat exchanger 40 to give heat to the indoor air to perform 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. After this high-pressure liquid refrigerant is led to the outdoor unit 1 by the liquid pipe 9 and reduced in pressure by the outdoor expansion valves 13a and 13b located on the upstream side of the outdoor heat exchangers 12a and 12b, the low-pressure liquid refrigerant is obtained. To the outdoor heat exchangers 12a and 12b. The low-pressure liquid refrigerant evaporates by taking heat from the outside air in the outdoor heat exchangers 12a and 12b, and becomes a low-pressure gas refrigerant. As described above, the low-pressure gas refrigerant is guided to the outdoor four-way valves 14a and 14b, and then returned to the compressor 10a through the low-pressure gas branch pipes 15a and 15b.

  Also in this operation pattern, the high / low pressure bypass pipe opening / closing valve 60 provided in the high / low pressure bypass pipe 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is closed.

[Heating subject (heating period): Operation pattern E4 ']
As shown in FIG. 9, even if it is a heating period such as winter and most of the indoor units 3 are in the heating operation, only some of the indoor units (in the figure, the indoor unit 3d) select the cooling operation. There may be.
In this case, the shunt controller of the indoor unit 3d is changed to the setting for the cooling operation. That is, the indoor side 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 49-3. Communicate.
When switching from the heating operation to the cooling operation in this way, after opening and closing the high-pressure gas branch pipe on-off valve 52 and allowing the high-pressure gas to flow through the high-pressure gas branch pipe bypass passage 54 and depressurizing the first capillary tube 55, The indoor four-way valve 48 is switched. By doing in this way, the pressure difference at the time of switching can be made as small as possible, and noise at the time of switching of the indoor side four-way valve 48 can be prevented.

  Since the outdoor heat exchangers 12a and 12b are in the heating period and the evaporation capacity required for the entire system is still large (for example, 100% of the capacity), the evaporator is similar to the operation pattern E4 (see FIG. 8). Is working as.

  Also in this operation pattern, the high / low pressure bypass pipe opening / closing valve 60 provided in the high / low pressure bypass pipe 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is closed.

[Heating subject (interim period): Operation pattern E2]
As shown in FIG. 10, the number of indoor units 3 for which the heating operation is selected is larger than the number of indoor units 3 for which the cooling operation is selected, and the operation pattern is in an intermediate period such as spring or autumn. It is shown.
In this operation pattern, the evaporation capacity is not required as much as in winter (for example, about 50% of the capacity). Therefore, the expansion valve 13a of the first outdoor heat exchanger 12a is fully closed, the first outdoor heat exchanger 12a is stopped, and the second Only the outdoor heat exchanger 12b is operated as an evaporator.

  Also in this operation pattern, the high / low pressure bypass pipe opening / closing valve 60 provided in the high / low pressure bypass pipe 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is closed.

[Oil return operation]
The oil return operation according to the present invention will be described below.
FIG. 11 shows a refrigerant circuit for an oil return operation in which the lubricating oil of the compressor 10 stored in the high pressure gas pipe 5 and the low pressure gas pipe 7 is returned to the compressor 10.
In the oil return operation, the high-pressure gas refrigerant flow between the high-pressure gas pipe 5 and the indoor heat exchanger 40 by switching the indoor four-way valve 48 during the heating operation (for example, the above-described all-heating all-unit operation: operation pattern E4). Is cut, and then the high / low pressure bypass pipe open / close valve (open / close valve) 60 of the high / low pressure bypass pipe (bypass pipe) 58 communicating the high pressure gas branch pipe 5c and the low pressure gas branch pipe 7c is opened. At this time, the high pressure gas flowing in the branch flow controller 46 flows through the high and low pressure bypass pipe 58 from the high pressure gas branch pipe 5c to the low pressure gas branch pipe 7c. Although the on-off valve 52 for the high-pressure gas branch pipe is opened, the pressure passing through the high-low pressure bypass pipe 58 rather than the pressure loss passing through the on-off valve 52 and through the indoor side four-way valve 46 and the second capillary tube 57. Since the pressure loss of the third capillary tube 62 is set so as to reduce the loss, most of the high-pressure gas refrigerant flows in the high-low pressure bypass pipe 58.

The third capillary tube 62 has a role of adjusting the flow rate of the gas refrigerant passing through the high / low pressure bypass pipe 58. That is, when the flow rate of the gas refrigerant passing through the high / low pressure bypass pipe 58 is excessively high, noise may occur in the high / low pressure bypass pipe 58. Therefore, the flow rate is reduced by the third capillary tube 62 to prevent the generation of noise. Thus, the third capillary tube 62 is used as a speed reduction means for preventing noise.
Further, since the capillary tube 62 has a shape in which the pipe is wound in a spiral shape, the capillary tube 62 itself has high rigidity with respect to the straight pipe, and increases the eigenvalue with respect to vibration. Although not shown, the high / low pressure bypass pipe 58 may be fixed to a nearby rigid member (for example, a frame) to prevent vibrations.

As described above, according to the present embodiment, the following operational effects are obtained.
Since a high-pressure gas flows through the high-low pressure bypass pipe 58 to form a refrigerant circuit that shortcuts the refrigerant flow path closer to the indoor heat exchanger 40 than the high-low pressure bypass pipe 58, the high-low pressure difference is maintained. High pressure gas can flow from the high pressure gas pipe 5 to the low pressure gas pipe 7. Thereby, regardless of the indoor and outdoor loads, the flow rate of the gas refrigerant can be kept high, and the lubricating oil adhering to the inner wall of the refrigerant pipe can be effectively recovered.

  By bypassing the indoor heat exchanger 40, which causes a pressure loss of the gas refrigerant, and connecting the high-pressure gas branch pipe 5c and the indoor-side low-pressure gas pipe 7c, the gas refrigerant can flow at a high flow rate, which is effective. An oil return can be performed. In particular, when R410A is used as the refrigerant, the pressure loss is small, so that the pipe diameter can be reduced if the pressure loss equivalent to the conventional one is allowed. Thereby, the flow rate of the gas refrigerant can be further increased, and oil recovery can be performed more efficiently.

  Since the indoor heat exchanger 40 is bypassed so that the gas refrigerant does not pass through the indoor heat exchanger 40, noise during the oil return operation is not transmitted to the room.

  Since the high-pressure gas pipe 5, the high-pressure gas branch pipe 5c, the high-low pressure bypass pipe 58, the indoor-side low-pressure gas branch pipe 7c, and the low-pressure gas pipe 7 are sequentially formed to perform oil return. The inside of the pipe can be washed simultaneously (oil recovery) in a short time.

  Since the oil return operation can be realized by a simple configuration in which the high / low pressure bypass pipe 58 is added, the cost can be minimized.

  Since there is no need to return the liquid refrigerant to the compressor unlike the liquid bag, the temperature under the dome of the compressor can be maintained at a predetermined value or more without lowering. Therefore, the oil concentration in the compressor does not decrease, and damage to the compressor due to insufficient lubrication can be avoided. In addition, since the temperature under the dome does not decrease, when switching to the heating operation after the end of the oil return operation, the high pressure can be immediately increased, so that the start-up of the heating can be accelerated.

  Unlike the liquid bag, it is not necessary to flow the low-pressure liquid refrigerant through the indoor heat exchanger, so the temperature of the indoor heat exchanger does not decrease. Therefore, when switching to the heating operation after the end of the oil return operation, the start-up of the heating can be accelerated.

In addition, as shown in FIG. 12, it is also possible to implement | achieve the structure which shortcuts the high pressure gas branch pipe 5c and the indoor side low pressure gas branch pipe 7c, without using the high and low pressure bypass pipe 58. FIG.
In the figure, a diversion unit 46 'is shown. The diversion unit 46 ′ omits the high / low pressure bypass pipe 58 of the diversion unit 46 described above, and is provided with a variable throttle 57 ′ instead of the second capillary tube 57. Thereby, the flow path which shortcuts the high-pressure gas branch pipe 5c and the indoor side low-pressure gas branch pipe 7c can be formed. When the oil return operation is performed by forming this shortcut channel, the throttle of the variable throttle 57 ′ is opened to reduce the channel resistance and increase the flow rate of the gas refrigerant flow.

According to the present embodiment, the number of outdoor heat exchangers 12 is two, but the number is not limited to this, and may be changed as appropriate according to the required capacity.
Further, the number of indoor units 3 is appropriately changed according to the application target.
Moreover, although the number of the compressors 10 is two, the number of compressors is not limited to this, and may be changed as appropriate according to the required capacity.

It is the air conditioning free multi air conditioner of this invention, and is the schematic block diagram which showed the driving | running pattern of all the cooling unit operation. It is the schematic block diagram which showed the driving | operation pattern of the cooling only operation | movement with a stop indoor unit. It is the schematic block diagram which showed the driving | running pattern of the cooling main driving | operation in the air_conditioning | cooling period. It is the schematic block diagram which showed the cooling main operation | movement in the intermediate | middle period, and showed the operation pattern within the control range of the outdoor fan. It is the schematic block diagram which showed the driving | running pattern in the cooling main operation | movement in the intermediate | middle period, in the control range of an outdoor fan, and when the required condensation capacity is comparatively small. It is a schematic block diagram which showed the driving | running pattern of low external temperature which is a cooling / heating balance driving | operation. It is the schematic block diagram which showed the driving | running pattern which is a cooling / heating balance driving | operation and a low voltage | pressure is in an allowable range. It is the schematic block diagram which showed the driving | running pattern of all heating all-unit driving | operation. It is the schematic block diagram which showed the driving | running pattern of the heating main driving | operation in the heating period. It is the schematic block diagram which showed the driving | running pattern of the heating main driving | operation in the intermediate period. It is the schematic block diagram which showed the driving | running pattern of the oil return driving | operation. It is a schematic block diagram showing a modified example of the oil return operation. It is the schematic block diagram which showed the conventional air conditioning free multi air conditioner.

Explanation of symbols

1 Outdoor unit (outdoor unit)
3 Indoor units (indoor units)
5 High-pressure gas pipe 7 Low-pressure gas pipe 9 Liquid pipe 48 Indoor four-way valve 50 Low-pressure bypass pipe 55 First capillary tube 57 Second capillary tube 58 High-low pressure bypass pipe (bypass pipe)
60 Open / close valve for high / low pressure bypass pipe (open / close valve)
62 3rd capillary tube (noise prevention means, speed reduction means)

Claims (5)

The room of an air conditioner having an indoor heat exchanger connected to an outdoor unit by a low-pressure gas pipe, a high-pressure gas pipe and a liquid pipe and supplied with a refrigerant from the high-pressure gas pipe or the liquid pipe to exchange heat with indoor air In the machine
An air conditioner indoor unit comprising a bypass pipe that connects the high-pressure gas pipe and the low-pressure gas pipe to bypass the indoor heat exchanger, and the bypass pipe is provided with an on-off valve. . The indoor unit of an air conditioner according to claim 1, wherein the bypass pipe is provided with noise prevention means for preventing noise caused by the refrigerant flowing in the bypass pipe. The indoor unit of an air conditioner according to claim 2, wherein the noise preventing means is a speed reducing means provided in the bypass pipe. An outdoor unit including a compressor for compressing refrigerant and an outdoor heat exchanger for exchanging heat with the outside air;
A plurality of indoor units including an indoor heat exchanger connected to the outdoor unit by a low-pressure gas pipe, a high-pressure gas pipe and a liquid pipe and supplied with a refrigerant from the high-pressure gas pipe or the liquid pipe to exchange heat with room air; In an air conditioner equipped with
An air conditioner comprising at least one indoor unit according to any one of claims 1 to 3. An outdoor unit including a compressor for compressing refrigerant and an outdoor heat exchanger for exchanging heat with the outside air;
A plurality of indoor units including an indoor heat exchanger connected to the outdoor unit by a low-pressure gas pipe, a high-pressure gas pipe and a liquid pipe and supplied with a refrigerant from the high-pressure gas pipe or the liquid pipe to exchange heat with room air; In the operation method of the air conditioner provided with
An operation method for an air conditioner, wherein an oil return operation is performed in which a gas refrigerant is allowed to flow between the high-pressure gas pipe and the low-pressure gas pipe by bypassing the indoor heat exchanger.

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