JPH04103970A - Multi-type air conditioner - Google Patents

Abstract

PURPOSE:To discharge a flowing refrigerant condensed and staying in a high pressure gaseous refrigerant branch pipe into a low pressure gaseous refrigerant branch pipe by a method wherein a bypassing pressure reducing mechanism is connected between the high pressure gaseous refrigerant branch pipe and an indoor heat exchanger, and each of bypassing opening or closing valves is connected between each of connection points between the bypassing pressure reducing mechanisms and the low pressure gaseous refrigerant branch pipe. CONSTITUTION:In the event that an indoor device 2a is stopped and an indoor device 2b performs a heating operation, condensed liquid refrigerant is accumulated in a high pressure gaseous refrigerant pipe 18a from a branch part 18' of a high pressure gaseous refrigerant main pipe 18 to a heating changing-over solenoid opening or closing valve 10a being closed, so that a bypassing solenoid opening or closing valve 12a is opened at a proper time. With such an arrangement, liquid refrigerant is flowed in a low pressure gaseous refrigerant branch pipe 19a through a bypassing capirally 14a and further flowed in a low pressure gaseous refrigerant main pipe 19 and finally discharged out of the outdoor device 1. In addition, condensation and accumulation of the refrigerant flowed from the high pressure gaseous refrigerant branch pipe 18a through capirally tubes 14a, 15a are generated at an indoor heat exchanger 9a of the indoor device 2a being stopped. However, it is possible to flow the liquid refrigerant within the indoor heat exchanger 9a into the low pressure gaseous refrigerant branch pipe 19a through the capirally tube 15a under an opened state of the solenoid valve 12a.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to refrigeration cycle piping for a multi-air conditioner that can simultaneously perform cooling and heating operations for multiple indoor units connected to a common outdoor unit. It also relates to a means for discharging liquid refrigerant that has accumulated or condensed in an indoor heat exchanger.

[Prior Art] In conventional multi-air conditioning systems that have one or more indoor units connected to piping connected to one outdoor unit, these indoor units are either in cooling operation (including dehumidification) or heating operation. I was only able to drive one or the other.

In recent years, we have developed a multi-air conditioner that combines multiple indoor units with a common outdoor unit, allowing simultaneous cooling and heating operation, allowing you to freely select between cooling operation for any indoor unit and heating operation for the others. is in progress. In such a multi-air conditioner, each indoor unit is connected to the outdoor unit through branch pipes branching from the liquid refrigerant main pipe, high-pressure gas refrigerant main pipe, and low-pressure gas refrigerant main pipe, respectively, and the gas side branch pipe is connected to the cooling/heating pipe. A switching on-off valve is installed.

[Problems to be solved by the invention In such a multi-air conditioner capable of simultaneous cooling and heating operation,
Refrigerant may condense and accumulate in the high-pressure gas refrigerant branch pipe between the branch of the high-pressure gas refrigerant main pipe and the cooling/heating switching valve of the stopped indoor unit, and the amount of condensation is greater than the length of the branch pipe. However, in the conventional technology, no consideration was taken to discharge the condensed and accumulated liquid refrigerant, which caused the problem of a refrigerant shortage in the indoor unit during operation. .

In addition, the conventional technology does not take into account the pressure difference before and after the opening/closing valve when the liquid refrigerant accumulated in the indoor heat exchanger of the indoor unit that is stopped is discharged by opening the cooling/heating switching valve. Since the pressure difference is large, there is a problem in that refrigerant flow noise is generated when the liquid refrigerant passes through the on-off valve.

One object of the present invention is to discharge the flowing refrigerant condensed and retained in the high-pressure gas refrigerant branch pipe to the low-pressure gas refrigerant branch pipe, and further to reduce the refrigerant flow noise when the flowing refrigerant is discharged from the indoor heat exchanger. With the goal.

Another object of the present invention is to adjust the opening time of the on-off valve that is opened to discharge these flowing refrigerants, thereby allowing efficient refrigerant circulation.

[Means for Solving the Problem] The above-mentioned object is achieved by the configuration of the multi-air conditioner according to any one of claims 1 to 4 at the head of the claims,
Further, the above-mentioned other objects are achieved by the structure according to claim 5 or 6.

[Function] In the multi air conditioner of claim 1, the liquid refrigerant condensed and retained in the high pressure gas refrigerant branch pipe opens one or more selected bypass on-off valves, and the multi air conditioner of claim 2 In the harmonizer, the bypass opening/closing valve is opened, claim 3.
In the multi air conditioner according to claim 4, the bypass on-off valve of the first bypass flow path is opened, and in the multi air conditioner according to claim 4, the variable bypass expansion valve of the first bypass flow path is opened. The refrigerant is gradually discharged to the refrigerant branch pipe. After the liquid refrigerant is discharged, even if gas refrigerant flows through the open valve, the gas refrigerant is discharged as a flowing refrigerant by the pressure reducing device.

Furthermore, the retentive liquid refrigerant in the indoor heat exchanger is defined in claim 1 or 2.
In the multi-air conditioner of Claim 3, the bypass on-off valve is opened as described above; in the multi-air conditioner of Claim 3, the bypass on-off valve of the second bypass flow path is opened; In this case, by opening the variable bypass expansion valve of the second bypass passage, the low-pressure gas refrigerant is gradually discharged to the branch pipe. As a result, the pressure inside the indoor heat exchanger decreases, and the pressure difference between the front and rear of the cooling switching valve also decreases, so that the generation of refrigerant flow noise when the cooling switching valve is opened subsequently can be reduced.

Furthermore, in the multi air conditioner according to claim 5 or 6, 1
The valve is opened only for the time necessary to discharge the accumulated liquid refrigerant.

[Example] An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a refrigeration cycle system diagram of a multi-air conditioner capable of simultaneous cooling and heating operation, which combines an outdoor iml and an indoor air conditioner 1112a, 2b. The outdoor unit 1 has a compressor 3, four-way valves 4a and 4b.
, outdoor heat exchangers 5a, 5b, outdoor expansion valves 6a, 6c
, liquid receiver 7, accumulator 13. Bypass expansion valve 16
, has a check valve 17. On the other hand, the indoor units 2a and 2b have indoor expansion valves 8a and 8b, and indoor heat exchangers 9a and 9b, respectively.
and each indoor unit has a

Respectively, heating switching electromagnetic switching valves 10a, 10b, cooling switching electromagnetic switching valves 11a, llb, bypass electromagnetic switching valve 12.
a, 12b, capillary 14a, 14b, capillary 1
5a and 15b are provided.

High-pressure gas refrigerant branch pipes 18a and 18b branch from a high-pressure gas refrigerant main pipe 18, a low-pressure gas refrigerant main pipe 19, and a liquid refrigerant main pipe 20 connected to the outdoor unit 1, respectively.

Low pressure gas refrigerant branch pipes 19a, 19b and liquid refrigerant branch pipes 20a, 20b are connected to each indoor unit.

The basic refrigeration cycle includes a compressor 3 and a four-way valve 4a.

4b, outdoor heat exchanger 5a, 5b, outdoor expansion valve 6a,
6b, liquid receiver 7, liquid refrigerant main pipe 20, same branch pipe 20a
.

20b, indoor expansion valves 8a, 8b, indoor heat exchanger 9a.

9b, heating switching electromagnetic switching valves 10a, 10b, cooling switching electromagnetic switching valves 11a, llb, high pressure gas refrigerant branch pipe 1
8a, 18b, main pipe 18, low pressure gas refrigerant branch pipe 1
9a, 19b, main piping 19, accumulator 13,
Consisted of.

Heating switching electromagnetic switching valves 10a, 10b and cooling switching electromagnetic switching valves 11a of each indoor unit 2a, 2b,
High pressure gas refrigerant branch pipe 18a on the front side of llb,
From 18b to low pressure gas refrigerant branch pipes 19a and 19b are capillaries 14a and 14b and bypass electromagnetic on-off valve 1, respectively.
2a and 12b are connected in series. In addition, bypass electromagnetic on-off valves 12a, 1 are connected to the indoor heat exchangers 9a, 9b.
2b and the cab 51 4a, 14b are connected to the cab 9 in parallel with the cooling switching electromagnetic on-off valve 11a, llb.
i month 5a and 15b are connected.

The pressure in each pipe between the outdoor unit 1 and the indoor units 2a and 2b is determined by the high-pressure gas main pipe 18 and the branch pipe 18a.

In 18b, a pressure Pd close to the discharge pressure of the compressor 3, a low-pressure gas main pipe 19; in the same branch pipes 19a and 19b, a pressure Ps close to the suction pressure of the compressor 3, a high-pressure liquid refrigerant pipe 20,
Inside the branch pipes 20a and 20b, the pressure P1 is close to the pressure inside the liquid receiver 7. Between these pressures P d >
There is a relationship of P L > P s.

When both indoor units 2a and 2b are in cooling operation, the refrigeration cycle is as follows. The gas refrigerant discharged from the compressor 3 passes through four-way valves 4a and 4b and is liquefied in outdoor heat exchangers 5a and 5b, and is then liquefied in outdoor expansion valves 6a and 6b (fully open at this time), liquid receiver 7,
The high-pressure liquid refrigerant passes through the main pipe 2o and the branch pipes 20a and 20b, and after being depressurized by the indoor expansion valves 8a and 8b, the indoor heat exchanger 9a
.

It is vaporized at 9b, and the cooling switching electromagnetic on-off valve 11a.

11b (at this time, the heating switching electromagnetic on-off valve 10a,
40b is closed), low pressure gas refrigerant branch pipes 19a, 19b,
It passes through the main pipe 19 and the accumulator 13, returns to the compressor 3, and is again subjected to discharge ratio.

When both indoor units 2a and 2b are in heating operation, the refrigeration cycle is as follows. The gas refrigerant discharged from the compressor 3 passes through four-way valves 4a and 4b (and one passes through a check valve 17).
, high-pressure gas refrigerant main pipe 18, branch pipes 18a, 18b
, passes through the heating switching electromagnetic on-off valves 10a and 10b (at this time, the cooling switching electromagnetic on-off valves 11a and llb are closed), liquefies in the indoor heat exchangers 9a and 9b, and indoor expansion valves 8a and 8b (fully opened at this time). , high pressure liquid refrigerant branch pipes 20a, 20b,
The main pipe 20 passes through the liquid receiver 7, and the outdoor expansion valve 6a.

It is depressurized at 6b, liquefied at outdoor heat exchangers 5a and 5b, and returns to compressor 3 via four-way valves 4a and 4b and accumulator 13.

When the indoor unit 2a is in the cooling operation and the indoor unit 2b is in the heating operation, and the cooling load is greater than the heating load, the refrigeration cycle is as follows. A part of the gas refrigerant discharged from the compressor 3 passes through the four-way valve 4b, is liquefied in the outdoor heat exchanger 5b, and is then fully opened to the outdoor expansion valve 6b.

The liquid refrigerant passes through the liquid receiver 7 and the liquid refrigerant main pipe 20, joins with the liquid refrigerant described below coming from the liquid refrigerant branch pipe 20b, enters the liquid refrigerant branch pipe 20a, is depressurized by the indoor expansion valve 8a, and is used for indoor heat exchange. It is vaporized in the container 9a, and returns to the compressor 3 through the cooling switching electromagnetic switching valve 11a (at this time, the heating switching electromagnetic switching valve 10a is closed), the low-pressure gas refrigerant branch pipe 19a, the main pipe 19, and the accumulator 13. On the other hand, the other parts of the discharge gas refrigerant from the compressor 3 are connected to the four-way valve 4a, the high-pressure gas refrigerant main pipe 18, the same branch pipe 18b, and the heating switching electromagnetic on-off valve 10b (at this time, the cooling switching electromagnetic on-off valve 11b is closed), is liquefied in the outdoor heat exchanger 9b, and is liquefied by the indoor expansion valve 8b (fully open at this time).
Furthermore, the liquid refrigerant main pipe 20 passes through the liquid refrigerant branch pipe 20b.
As described above, the liquid refrigerant from the refrigerant flows into the branch pipe 20a.

When the indoor unit 2a is in heating operation, the indoor unit 2b is in cooling operation, and the heating load is greater than the cooling load, the refrigeration cycle is as follows. The gas refrigerant discharged from the compressor 3 is distributed through a four-way valve 4a, a high-pressure gas refrigerant main pipe 18, and a branch pipe 18a.
The refrigerant passes through the heating switching electromagnetic on-off valve 10a (at this time, the cooling switching electromagnetic on-off valve 11a is closed), becomes a liquid refrigerant in the indoor heat exchanger 9a, and passes through the indoor expansion valve 8a (fully open at this time) and the liquid refrigerant branch pipe 20a. The liquid refrigerant then branches into the liquid refrigerant main pipe 20 and the branch pipe 20b. The liquid refrigerant branched to the liquid refrigerant main pipe 20 is transferred from the liquid receiver 7 to the outdoor expansion valve 6
A, the pressure is reduced through the outdoor heat exchanger 6a, the gas refrigerant passes through the four-way valve 4a, merges with the gas refrigerant coming from the low-pressure gas refrigerant main pipe 19 (described later), passes through the accumulator 13, and is compressed by the compressor I.
Return to 13. On the other hand, the liquid refrigerant branched to the liquid refrigerant branch pipe 20b is depressurized by the indoor expansion valve 8b and vaporized by the indoor heat exchanger 9b, and the cooling switching electromagnetic on-off valve 11b (at this time, the heating switching electromagnetic on-off valve 10b is closed). , low pressure gas refrigerant branch pipe 19
b. It passes through the main pipe 19 and joins with the gas refrigerant coming from the four-way valve 4a described above.

In the refrigeration cycle described above, when any of the indoor units is stopped, the expansion valve (8a or 8b) of that indoor unit, the electromagnetic on-off valve (10) for cooling switching and heating switching
a, lla or 10b, 11b) are closed. Also,
Depending on the required heat load, both or one of the outdoor heat exchangers 5a and 5b may be used.

Now, the operation related to discharging the retained liquid refrigerant, which is a feature of the present invention, will be explained below.

In FIG. 1, when the indoor unit 2a is stopped and the indoor unit 2b is in heating operation, that is, the heating cut-off valve and the cooling switching electromagnetic on-off valves 11a and llb are both closed, and the indoor expansion valve 8a is closed. When the expansion valve 8b is open, the high-pressure gas refrigerant branch pipe 18a between the branch part 18' of the high-pressure gas refrigerant main pipe 18 and the closed heating switching solenoid valve 10al is It is thought that condensed liquid refrigerant stagnates. Therefore, in this embodiment, at an appropriate time.

The bypass electromagnetic on-off valve 12a is opened. As a result, the above liquid refrigerant flows through the bypass capillary 14a to the low pressure gas refrigerant branch pipe 19a whose pressure is as low as Ps, further flows through the low pressure gas refrigerant main pipe 19 and is discharged to the outdoor unit 1, so that the condensed refrigerant can eliminate the retention of

In addition, the indoor heat exchanger 9a of the indoor unit 2a that is stopped is also connected to the capillaries 14a, 15 along with the high pressure gas refrigerant branch pipe 18a.
It is assumed that condensation and stagnation of the refrigerant that entered the indoor heat exchanger 9a occurs through the bypass capillary 15a by opening the bypass electromagnetic on-off valve 12a. The low pressure gas refrigerant can flow into the branch pipe 19a having a low pressure of Ps.

Conventionally, the liquid refrigerant accumulated in the indoor heat exchanger 9a is transferred to the low-pressure gas refrigerant branch pipe 19 by opening the cooling switching electromagnetic on-off valve 11a.
a, but when the valve 11a is opened, the valve 1
There was a problem in that refrigerant flow noise was generated due to the large pressure difference before and after 1a. In contrast, in this example,
While the cooling switching electromagnetic on-off valve 11a remains closed, the bypass electromagnetic on-off valve 12a is opened, and the liquid refrigerant in the indoor heat exchanger 9a flows into the low-pressure gas refrigerant branch pipe 19a via the capillary 15a and the bypass electromagnetic on-off valve 12a.

At this time, the difference in pressure across the bypass on-off valve 12a is small due to the pressure drop in the capillary 15a, so there is little refrigerant flow noise. Note that after the liquid refrigerant has finished flowing through the bypass electromagnetic on-off valve 12a, the cooling switching electromagnetic on-off valve 11a
When the valve 11a is opened to switch to cooling mode, the pressure difference across the valve 11a is small, so the refrigerant flow noise generated by the valve 11a is small.

In addition, in FIG. 1, when the indoor unit 2a is in cooling operation, the cooling switching electromagnetic on-off valve 11a is open, and the heating switching electromagnetic on-off valve 10a is open, regardless of the operating state of the indoor unit 2b.
is closed, and the indoor expansion valve 8a is opened. In this case, both the bypass capillaries 14a and 15a communicate with the high-pressure gas refrigerant branch pipe 18a, so the capillary 14a,
High-pressure gas refrigerant flows through the capillaries 15a, but since the cooling switching electromagnetic on-off valve 11a is open, these capillaries 14a
, 15a, the high pressure gas refrigerant flows through the low pressure gas refrigerant branch pipe 19a (lower than the pressure Px□ in the indoor heat exchanger 9a
Since it flows to the pipe pressure Ps), the indoor unit 2a during cooling operation
High temperature gas refrigerant is prevented from flowing into the indoor heat exchanger 9a, and the performance of the indoor unit during cooling operation is not reduced.

At the same time, if the bypass solenoid on-off valve 12a is also open,
Since there is a pressure loss in the refrigerant flowing through the bypass capillary 15a, the bypass electromagnetic on-off valve 12a has a small pressure loss.
Since more refrigerant flows through the air conditioner, similarly to the above, high temperature gas refrigerant is prevented from flowing into the indoor heat exchanger 9a during cooling operation.

FIG. 2 shows another embodiment around the indoor unit 2a, and the same applies to the area around the indoor unit 2b. The rest of the configuration of the refrigeration cycle is the same as in FIG. This also applies to other embodiments shown in FIG. 3 and subsequent figures.

In Fig. 2, indoor unit It & 2a is stopped and indoor unit 2b
When in heating operation, branch part 1 of high pressure gas refrigerant main pipe 18
As in FIG.
The capillary 14 is opened by opening the bypass solenoid on-off valve 12a.
a to the low-pressure gas refrigerant branch pipe 19a. Furthermore, when the indoor unit 2a is switched to cooling and the other indoor units are switched to heating, in this embodiment, bypass capillaries 14a and 15a are not connected, so indoor unit 2a
High pressure gas refrigerant does not flow into the indoor heat exchanger 9a while the indoor heat exchanger 9a is stopped.

In addition, in order to switch the indoor unit 2a from the heating operation to the cooling operation in FIG. This has the effect of reducing the pressure difference between the front and rear sides of the electromagnetic on-off valve 11a and reducing the refrigerant flow noise when the cooling switching electromagnetic on-off valve 11a is opened.

FIG. 3 shows the bypass electromagnetic on-off valve 12a in FIG.
21 and bypass capillaries 14a and 15 connected to this
An embodiment using variable bypass expansion valves 22 and 23 in place of a is shown. According to this embodiment, the refrigerant flow rate and pressure are kept constant by opening the bypass electromagnetic on-off valves 12a and 21 in the embodiment shown in FIG. 2, but this can be made variable depending on temperature conditions, etc. be.

FIG. 4 shows the bypass capillary 14a in FIG.
An embodiment is shown in which a bypass capillary 24 is added between the capillaries 24 and 15a, and a bypass electromagnetic on-off valve 21 is added between the connection point between the capillaries 24 and 14a and the low-pressure gas refrigerant branch pipe 19a. According to this embodiment, the bypass switching valve 1
By switching 2a and 21, the flow rate of the retained liquid refrigerant flowing into the low pressure gas refrigerant branch pipe 19a can be made variable.

FIG. 5 shows temperature sensors 25a, 25 on the inlet side of the bypass capillaries 14a, 15a in the indoor unit 2a of FIG.
This is an example in which the liquid refrigerant existing in the refrigerant can be detected based on the temperature. If the valve 12a is closed when liquid refrigerant is no longer detected, the bypass electromagnetic on-off valve 1
2a, the liquid refrigerant is the low pressure gas refrigerant branch pipe 19a.
It can be synchronized with the time until the end of the flow. As a result, the bypass on-off valve 12
It is possible to prevent the high-pressure gas refrigerant from flowing to the low-pressure gas refrigerant amount I'g19 without being condensed through a. Another means for adjusting the opening time of the bypass opening/closing valve 12a is to determine the opening time of the bypass opening/closing valve using a timer set to a time that is empirically known as the time required for discharging the stagnant liquid refrigerant. , and the same effect can be obtained by this.

In the embodiments shown in FIGS. 2, 3, and 4, the bypass valve (12
The opening times of a, 21.22.23) can be similarly adjusted.

FIG. 6 shows an embodiment corresponding to the embodiment shown in FIG. 1 and further expanded from the embodiment shown in FIG. 4. A series of bypass capillaries 30 to 34 are connected up to the heat exchanger 9a.

Bypass electromagnetic on-off valves 26 to 29 are connected between each of these mutual connection points and the low pressure gas refrigerant branch pipe 19a, respectively. By selecting the opening combinations of the bypass electromagnetic on-off valves 26 to 29, the decompression capillaries 30 to 34 are configured to flow the accumulated liquid refrigerant in the high pressure gas refrigerant branch pipe 18a and the indoor heat exchange m9a to the low pressure gas refrigerant branch pipe 19a.
The amount of pressure reduction can be variably selected. The opening time of these bypass solenoid on-off valves for discharging liquid refrigerant is as described above.
It can be controlled by temperature sensors 25a, 25b or by a timer.

Bypass capillary 14a shown in FIGS. 1 to 6,
Even if the bypass expansion valves 14b, 15a, 15b, 24.30-34 or the bypass expansion valves 22.23 are configured to adjust the amount of refrigerant bypassed by a flow rate adjustment valve, the same effects as in each of the above embodiments can be obtained. It will be done.

[9! , Bright Effects Since the present invention is configured as described above, it produces the effects as described below.

The bypass capillary and bypass on-off valve allow the liquid refrigerant condensed and accumulated in the high-pressure gas refrigerant branch pipe to be discharged to the low-pressure gas refrigerant branch pipe, as well as the liquid refrigerant condensed in the indoor heat exchanger.

The low-pressure gas refrigerant can be discharged to the branch piping without opening the cooling switching on-off valve, which prevents refrigerant shortages in the operating refrigeration cycle, and also reduces the pressure before and after the on-off valve. The refrigerant flow noise when the on-off valve is opened due to the large difference can be reduced.

In addition, it is possible to prevent high-pressure gas from flowing into the indoor heat exchanger of an indoor unit that is stopped or in cooling operation. If it is separated from the bypass route from the internal heat exchanger to the low pressure gas refrigerant branch pipe,
The above prevention becomes more reliable.

Furthermore, by using a variable expansion valve instead of the combination of a bypass on-off valve and a capillary, the flow rate and pressure of liquid refrigerant discharge can be controlled.

Similarly, by combining two or more bypass on-off valves and capillaries, the flow rate and pressure of liquid refrigerant discharge can be controlled.

Also, by installing a temperature sensor to detect the presence of liquid refrigerant or by using a timer.

The optimum opening time of the bypass on-off valve for discharging the accumulated liquid refrigerant can be determined, and it is possible to prevent the high-pressure gas refrigerant from flowing into the low-pressure side.

[Brief explanation of the drawing]

Fig. 1 is a refrigeration cycle system diagram according to an embodiment of the present invention;
The figures are partial views of another embodiment of the present invention, FIG. 3, FIG.
FIGS. 5 and 6 are also partial views showing other different embodiments of the present invention. 1...Outdoor unit 2a, 2b...Indoor unit 3.
...Compressor 4a, 4b...Four-way valve 5a, 5
b...Outdoor heat exchanger 6a, 6b...Outdoor expansion valve 7...Liquid receiver 8a, 8b...Indoor expansion valve 9a, 9b...Indoor heat exchanger 10a, 10b...Heating Switching electromagnetic on-off valve 11a, l
lb... Solenoid switching valve for cooling 12a, 12b...
Bypass electromagnetic on-off valve 13...Accumulator 14a, 14b...Bypass capillary 15a, 15
b...Bypass capillary 16...Outdoor bypass expansion valve 17...Check valve 18...High pressure gas refrigerant main pipe 19...Low pressure gas refrigerant main pipe 20...High pressure liquid refrigerant main pipe 18a, 18b...High pressure gas refrigerant branch pipe 19a, 1
9b...Low pressure gas refrigerant branch piping 20a, 20b...
Liquid refrigerant branch pipe 21... Bypass electromagnetic on-off valve 22.23... Bypass expansion valve 24... Bypass capillary 25a, 25b... Temperature detection sensor 26.27.28.29... Bypass electromagnetic on-off valve 30
．． 31.32.33.34. ...Bypass capillary and 1 other person Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] 1. A common outdoor unit and a plurality of indoor units are provided, and one end of the indoor heat exchanger of each indoor unit is connected to a high-pressure gas refrigerant branch pipe and a low-pressure gas refrigerant branch pipe through a heating/cooling switching valve. The other end of the indoor heat exchanger is connected to a liquid refrigerant branch pipe equipped with an indoor expansion valve, and each of these liquid refrigerant branch pipes, high pressure gas refrigerant branch pipe, and low pressure gas refrigerant branch pipe In a multi-air conditioner that is connected to the liquid refrigerant main piping, high-pressure gas refrigerant main piping, and low-pressure gas refrigerant main piping connected to the outdoor unit, respectively, for each indoor unit, the high-pressure gas refrigerant branch piping and indoor heat exchanger A plurality of bypass pressure reducing mechanisms connected in series are connected between one end and a bypass on-off valve is connected between each connection point between these bypass pressure reducing mechanisms and the low pressure gas refrigerant branch pipe. A multi-purpose air conditioner that is characterized by: 2. The multi air conditioner according to claim 1, wherein the number of the bypass pressure reducing mechanisms is two, and the number of the bypass opening/closing valve is one. 3 Equipped with a common outdoor unit and multiple indoor units, one end of the indoor heat exchanger of each indoor unit is connected to the high-pressure gas refrigerant branch pipe and the low-pressure gas refrigerant branch pipe via the heating/cooling switching valve. The other end of the indoor heat exchanger is connected to a liquid refrigerant branch pipe equipped with an indoor expansion valve, and these liquid refrigerant branch pipes, high-pressure gas refrigerant branch pipes, and low-pressure gas refrigerant branch pipes are connected to the outdoor unit. In a multi air conditioner that is connected to a liquid refrigerant main pipe, a high pressure gas refrigerant main pipe, and a low pressure gas refrigerant main pipe, for each indoor unit, between the high pressure gas refrigerant branch pipe and the low pressure gas refrigerant branch pipe, and, Between the one end of the indoor heat exchanger and the low-pressure gas refrigerant branch pipe, there are provided a first bypass flow path and a second bypass flow path, each of which is independent from the other, by series connection of a bypass pressure reduction mechanism and a bypass on-off valve.
A multi-air conditioner characterized by connecting a bypass flow path. 4. The multi-air conditioner according to claim 3, wherein a variable bypass expansion valve is used instead of the series connection of the bypass pressure reducing mechanism and the bypass opening/closing valve. 5. Detect the presence of liquid refrigerant in the high-pressure gas refrigerant branch pipe by checking the opening time of the bypass opening/closing valve or the variable bypass expansion valve when discharging the liquid refrigerant accumulated in the high-pressure gas refrigerant branch pipe to the low-pressure gas refrigerant branch pipe. 5. The multi-air conditioner according to claim 1, wherein the determination is made by a sensor or a preset timer. 6. The presence of liquid refrigerant at the one end of the indoor heat exchanger is detected by determining the opening time of the bypass on-off valve or the variable bypass expansion valve when discharging the liquid refrigerant accumulated in the indoor heat exchanger to the low-pressure gas refrigerant branch pipe. 6. The multi-air conditioner according to claim 1, wherein the determination is made by a sensor or a preset timer.