JPH10300245A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an air conditioner for enhancing reliability of a compressor by stopping the compressor, then lowering a differential pressure before and after the compressor in a short time, and holding an oil supply amount of the compressor at a suitable value. SOLUTION: The air conditioner comprises an indoor unit and a plurality of outdoor units, and bypass tubes 13 (13A, 13B) connecting a discharge side of a compressor 1 (1AA, 1AB, 1BA, 1BB) provided at the outdoor unit to a suction side of the compressor 1. In this case, the conditioner also comprises an oil separator 3 (3A, 3B) connected to a discharge side of the compressor 1, a check valve 14 (14A, 14B) provided at a downstream side of the separator 3, and a bypass tube 13 (13A, 13B) connected between the separator 3 and the valve 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner, and more particularly to an air conditioner having a circuit for bypassing a discharge pipe and a suction pipe to a discharge pipe of a compressor and a plurality of outdoor units connected to the compressor. It is suitable for ensuring the reliability of the machine.

[0002]

2. Description of the Related Art In a compressor, it is necessary to reduce a pressure difference between a discharge side and a suction side in order to reduce a load at the time of starting. There is known a structure in which a circuit for bypassing a discharge pipe and a suction pipe is attached, and a pressure difference is reduced in a short time by releasing a high-pressure gas to a low-pressure side.

However, in a large-capacity multi-type air conditioner having a plurality of outdoor units connected and having a common gas pipe and a liquid pipe, when one outdoor unit is stopped, the gas pipe and the liquid pipe are shared. Therefore, the differential pressure across the compressor in the stop outdoor unit does not decrease. for that reason,
In addition, there is a problem that the compressor must be restarted under a heavy load, and the oil level of the compressor is reduced due to the variation in the amount of oil in the compressor between the outdoor units. Reduction is a problem.

In order to solve this problem, for example, a method in which lubricating oil return pipes of the outdoor units are connected to each other by a pipe, and the oil is adjusted by flowing oil from a pipe having a larger amount of oil through the pipe is disclosed in, for example, Japanese Patent Laid-Open Publication No. It is known as described in JP-A-184048.

[0005]

The above prior art relates to a low-pressure chamber system in which a motor is provided on the suction side of a compressor, and the oil separator lacks an oil reserve. It is assumed that the compressor will be refueled. Therefore, in the case of a high-pressure chamber system in which the motor is provided on the discharge side of the compressor, the pressure inside the compressor is higher than the oil separator and the oil supply pipe pressure, so that an oil return loop is not formed. There is a problem that cannot be done.

An object of the present invention is to stop the compressor,
An object of the present invention is to provide an air conditioner in which the differential pressure between the compressors is reduced in a short time and the amount of oil supplied to each compressor is maintained at an appropriate value, thereby improving the reliability of the compressor.

[0007]

In order to achieve the above-mentioned object, the present invention has an indoor unit and a plurality of outdoor units, wherein a discharge side and a suction side of a compressor provided in the outdoor unit are provided. In an air conditioner connected between the two by a bypass pipe, an oil separator connected to the discharge side of the compressor,
It has a check valve provided downstream of the oil separator, and a bypass pipe connected between the oil separator and the check valve.

Accordingly, when the compressor is stopped, the oil separator is not affected by the pressure downstream of the check valve, and the high-pressure gas is released to the low-pressure side by the bypass pipe, so that the compressor can be operated in a short time. The differential pressure across the compressor is reduced. Therefore, restarting of the compressor is possible in a short time.

Further, another outdoor unit can be operated by a check valve.
Even when the unit is operating, the high-pressure part of this operating unit is shut off, and even if the outdoor unit with a low oil level due to insufficient oil in the oil separator is stopped, The pressure inside the oil separator can be reduced to a low pressure in a short time.

[0010] In the present invention, it is preferable that the oil separator of one outdoor unit and the oil separator of another outdoor unit are connected by an oil equalizing pipe. further,
In the present invention, it is preferable that the compressors are connected by an oil equalizing pipe. Furthermore, it is desirable to connect the compressor of a certain outdoor unit and the oil separator of another outdoor unit with an oil equalizing pipe.

Further, the present invention provides an air conditioner having an indoor unit and a plurality of outdoor units, wherein the discharge side and the suction side of a compressor provided in the outdoor unit are connected by a bypass pipe having an open / close valve. An oil equalizing pipe for connecting the outdoor units, and an openable and closable oil control valve provided in the oil equalizing pipe, and when the outdoor unit is stopped, the open / close valve is opened and the oil control valve is opened. is there.

When an outdoor unit is stopped, a high-pressure gas is released to the low-pressure side by the bypass pipe by opening an on-off valve of a bypass pipe connected between the discharge side and the suction side of the compressor. The differential pressure is reduced.
And at the same time, since the oil control valve provided in the oil equalization pipe connecting the other outdoor unit and the stop outdoor unit is opened, a pressure difference occurs between the outdoor units due to the operation of the other outdoor unit, By utilizing this pressure difference, it is possible to supply oil from the other outdoor unit to the outdoor unit whose oil level is low. Therefore, the amount of oil supplied to the compressor is appropriately maintained, and the reliability of the compressor, particularly, the reliability of starting and stopping can be improved. In addition, since piping for equalizing oil between the outdoor units can be performed only by connecting the piping of the outdoor units, the structure can be simplified, the on-site construction work can be reduced, and the reliability can be improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the flow of oil in external oil supply according to the prior art will be described with reference to FIG. In FIG.
The outdoor unit has two compressors 1AA and 1AB,
Taking the case of the compressor 1AA as an example, a refrigerant is sucked from the suction side of the compressor 1AA, and a mixture of the refrigerant and the oil flows through the compressor discharge pipe 21. In the oil separator 3A, the refrigerant gas and the oil are separated, and the refrigerant gas exits during the cycle through the gas pipe 22. On the other hand, the separated oil passes through the oil return pipe 17AA, flows into the compressor 1AA from the compressor oil supply port 23, flows through a portion requiring lubrication, and is discharged again to the gas pipe 21.

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a refrigeration cycle of an air conditioner according to one embodiment, FIG. 2 is a block diagram showing a configuration of a refrigeration cycle of an air conditioner according to another embodiment, and FIG. It is a block diagram showing composition of a refrigeration cycle of an air conditioner.

FIG. 1 shows a large-capacity multi-type air conditioner in which a plurality of outdoor units and a plurality of indoor units are connected to each other. In the figure, the refrigeration cycle includes an indoor heat exchanger 8, an indoor heat exchanger blower 9, an expansion valve 10 and the like on the indoor unit side, and a compressor 1, an outdoor heat exchanger 2, and an oil separator on the outdoor unit side. 3, four-way valve 4,
It is composed of an accumulator 5 and the like.

The outdoor unit and the indoor unit are connected by a common gas pipe 19 and a common liquid pipe 20 of the outdoor units A and B, respectively. Further, between the oil separator 3 and the four-way valve 4, a bypass control valve 11, a gas bypass circuit 13 composed of a bypass flow rate adjusting throttle device 12, and a check valve 14 are arranged in this order, and the outdoor units A and B are arranged. Each oil separator 3A, 3
Oil control valves 15A and 15B for connecting B, and oil equalizing pipes 18 having throttle devices 16A and 16B for adjusting the oil flow rate are provided. In normal operation, the bypass control valves 11A, 11B oil control valve 15A,
15B is controlled to be in a closed state.

If the oil level in the oil separator 3A is low due to some reason while the outdoor unit A alone is running, the compressors 1AA and 1AB are stopped and the bypass control valve 11A is opened at the same time. By releasing the high-pressure gas to the low-pressure pipe side, the pressure in the oil separator 3A can be reduced in a short time.

At this time, the oil control valve 15 of the oil supply pipe 18 is
Open A, 15B, and compressor 1BA, 1B of outdoor unit B
B is started and the pressure in the oil separator 3B is increased. This allows
There is a pressure difference between the oil separator 3A in the outdoor unit A and the oil separator 3B in the outdoor unit B, and oil can be supplied from the oil separator 3B to the oil separator 3A having an insufficient oil amount. Further, since the outdoor unit A and the outdoor unit B are connected by the common gas pipe 19, particularly during heating, the high-pressure gas of the outdoor unit B enters the vicinity of the compressors 1AA and AB through the four-way valve 4A of the outdoor unit A, thereby causing high pressure. However, since the check valve 14A is disposed between the bypass 13A and the four-way valve 4A, the high pressure is shut off by the check valve 14A of the outdoor unit A which is stopped, and the inside of the oil separator 3A receives the pressure of the outdoor unit B. Pressure can be reduced.

Further, even when both the outdoor units A and B are operating, the operation of the outdoor unit in which the oil level in the oil separator 3 is lowered is stopped, and the bypass control valve 13 of the stop unit is stopped.
And the oil control valves 15 of both are opened to achieve the same as described above.

In the example of FIG. 1, two outdoor units are connected. However, in the case of three or more outdoor units, oil can be supplied to the oil separator deficient in oil by the same control. At this time, the oil control valve 15 controls the oil control valve 15 so as to open the path between the oil separator having a shortage of oil and the oil separator having a sufficient amount of oil. No need to open.

Also, the operation of the outdoor unit having the oil separator deficient in oil has been described as completely stopped. However, for example, the gas bypass circuit is operated while the outdoor unit having the oil separator 3 deficient in oil is operated. To open or 2
By stopping only one of the compressors, a differential pressure can be applied between the oil separators 3 and oil can be supplied.

FIG. 2 shows a second embodiment. The difference from the first embodiment shown in FIG.
This is the point where the compressors 1A and 1B of B are connected by a soaking oil gap 18. In the outdoor units A and B on which the high-pressure chamber type compressors 1A and 1B are respectively mounted, the compressor 1A and the compressor 1B are connected by an oil equalizing pipe 18. For example, when only the outdoor unit A is operating and the oil level in the compressor 1A becomes insufficient for some reason and the oil level decreases, the compressor 1A
The compressor 1A is opened in a short time by opening the bypass control valve 11A and allowing high-pressure gas to escape to the low-pressure pipe side.
The pressure inside can be reduced.

At this time, the oil control valve 15 of the oil supply pipe 18 is
A and 15B are opened, and the compressor 1B of the outdoor unit B is started to increase the pressure inside the compressor 1B. As a result, a pressure difference is generated between the compressor 1A in the outdoor unit A and the compressor 1B in the outdoor unit B, and the compressor 1A having a shortage of the oil amount is supplied to the compressor 1A.
B can supply oil.

FIG. 3 shows a third embodiment. The difference from the first and second embodiments shown in FIGS. 1 and 2 is that the oil separator 3A of the outdoor unit A and the outdoor unit B Compressor 1
B is connected by an oil equalizing pipe 18. Specifically, an outdoor unit A on which one oil separator 3A and a plurality of compressors 1AA and 1AB are mounted, and one high pressure chamber type compressor 2B
The oil separator 3A and the compressor 1B are connected by an oil equalizing pipe 18 in the outdoor unit B equipped with.

For example, when the oil in the oil separator 3A is insufficient for some reason and the oil level is lowered when only the outdoor unit A is operating, the compressor 1A is stopped and the bypass control valve 11A is simultaneously operated. By releasing the open high-pressure gas to the low-pressure pipe side, the pressure in the oil separator 3A can be reduced in a short time.

At this time, the oil control valve 15 of the oil supply pipe 18
A and 15B are opened, and the compressor 1B of the outdoor unit B is started to increase the pressure inside the compressor 1B. This causes a pressure difference between the oil separator 3A in the outdoor unit A and the compressor 1B in the outdoor unit B, and the oil separator 3A having an insufficient oil amount.
Can be supplied with oil from the compressor 1B.

[0027]

As described above, according to the present invention, when the compressor is stopped, the oil separator is not affected by the pressure downstream of the check valve, and the compressor is moved to the low pressure side by the bypass pipe. The high pressure gas will be released. Therefore, the differential pressure across the compressor can be reduced in a short time, and the amount of oil supplied to each compressor can be maintained at an appropriate value, so that an air conditioner with improved compressor reliability can be obtained.

Also, in a large-capacity multi-type air conditioner to which an outdoor unit containing a plurality of compressors is connected, when a certain outdoor unit is stopped, it is provided in an oil equalizing pipe connecting the outdoor units. Since the opened oil control valve is opened, it is possible to supply oil to the outdoor unit whose oil level is low by utilizing the pressure difference between the outdoor units. Therefore, the amount of oil supplied to the compressor is appropriately maintained, and the reliability of the compressor, particularly, the reliability of starting and stopping can be improved. In addition, pipes for equalizing oil between the outdoor units can be formed only by connecting the pipes of the outdoor units, so that the structure can be simplified, and an air conditioner that improves reliability with less on-site construction work can be obtained. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a refrigeration cycle of an air conditioner according to one embodiment.

FIG. 2 is a block diagram showing a configuration of a refrigeration cycle of an air conditioner according to another embodiment.

FIG. 3 is a block diagram showing a configuration of a refrigeration cycle of an air conditioner according to another embodiment.

FIG. 4 is a block diagram showing a configuration of a refrigeration cycle of a conventional air conditioner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Outdoor heat exchanger, 3 ... Oil separator, 4 ... Four-way valve, 5 ... Accumulator, 6 ... Refrigerant amount regulator, 7 ... Blower for outdoor heat exchanger, 8 ... Indoor heat exchanger, 9 … Blower for indoor heat exchanger, 10… Expansion valve, 11… Bypass control valve, 12…
Throttling device for bypass flow rate adjustment, 13 gas bypass circuit,
14 ... check valve, 15 ... oil control valve, 16 ... throttle device for oil flow adjustment, 17 ... oil return pipe, 18 ... oil equalizing pipe, 19 ... common gas pipe, 20
... common liquid pipe, 21 ... compressor discharge pipe, 22 ... gas pipe.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Taku Michibata 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture Inside the Air Conditioning Systems Division, Hitachi, Ltd. In the laboratory

Claims (5)

[Claims] 1. An air conditioner having an indoor unit and a plurality of outdoor units, wherein a bypass pipe is connected between a discharge side and a suction side of a compressor provided in the outdoor unit. An oil separator connected to a discharge side; a check valve provided downstream of the oil separator; and the bypass pipe connected between the oil separator and the check valve. An air conditioner characterized by the above-mentioned. 2. The air according to claim 1, wherein the oil separator of one outdoor unit and the oil separator of another outdoor unit are connected by an oil equalizing pipe. Harmony equipment. 3. The air conditioner according to claim 1, wherein the compressors are connected by an oil equalizing pipe. 4. The air conditioner according to claim 1, wherein the compressor of one of the outdoor units and the oil separator of another of the outdoor units are connected by an oil equalizing pipe. apparatus. 5. An air conditioner comprising: an indoor unit and a plurality of outdoor units, wherein a discharge pipe and a suction pipe of a compressor provided in the outdoor unit are connected by a bypass pipe having an open / close valve. An oil equalizing pipe connecting between the outdoor units, and an openable and closable oil control valve provided in the oil equalizing pipe, wherein when the outdoor unit is stopped, the open / close valve is opened and the oil control valve is opened. An air conditioner characterized by opening.