JP3148403B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner in which a plurality of outdoor units are connected in parallel to piping between units extending from an indoor unit, and more particularly to a pressure inside a case of a compressor incorporated in each of the outdoor units. Is related to oil control when different values are set.

[0002]

2. Description of the Related Art In general, there is known an air conditioner in which a plurality of outdoor units are connected in parallel to piping between units extending from an indoor unit, and compressors built in each outdoor unit are connected by an oil return pipe. (For example, JP-A-4-93561). In this type, since a plurality of outdoor units are connected to the piping between the units, there is a disadvantage that the amount of lubricating oil circulating between the outdoor units together with the refrigerant becomes unbalanced for each outdoor unit. In such a case, oil is recovered from another compressor through an oil return pipe to a compressor deficient in lubricating oil.

[0003]

However, when the pressure in the case of the compressor becomes high during the operation of the compressor,
During operation of this compressor, oil cannot be recovered from another compressor into the case. In this case, if the oil is collected in the suction pipe of the compressor in which the pressure in the case becomes high, while the compressor in which the pressure becomes high in the case is stopped,
Since oil flows directly into the compression section, there is a problem in that oil compression occurs at the time of startup, leading to damage to the compressor.

[0004] Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to surely supply oil from another compressor to a compressor whose inside becomes high in pressure regardless of whether the compressor is operating or stopped. To provide an air conditioner capable of recovering air.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a method of connecting a plurality of outdoor units in parallel to a pipe between units extending from an indoor unit, and connecting a plurality of outdoor units to the respective compressors. A first return pipe for returning oil from the oil return pipe directly into the case of the high-pressure side compressor in an air conditioner in which the pressure in the case is set to be different and the compressors are connected by an oil return pipe; A second return pipe returning to the suction pipe of the high-pressure compressor, returning oil to the suction pipe through the second return pipe while the high-pressure compressor is operating, and returning oil to the suction pipe while the compressor is stopped. A control means for returning to the inside of the case through the first return pipe is provided.

Further, the present invention has a plurality of compressors connected in parallel, and a common oil separator connected to a discharge pipe of these compressors, and these compressors have different case pressures. In the air conditioner set as described above, an oil return pipe for returning the oil separated by the oil separator to the compressor whose case is on the high pressure side is a first return pipe directly connected to the case of the high pressure side compressor. And a second return pipe connected to the suction pipe of the high-pressure side compressor. While the high-pressure side compressor is operating, oil is returned to the suction pipe through the second return pipe, and the compressor is stopped. Is characterized in that a control means for returning the oil into the case through the first return pipe is provided.

[0007]

If the oil shortage occurs during the operation of the compressor in which the pressure in the case becomes high, the oil is returned to the compressor from the suction pipe through the second return pipe. When the compressor is stopped, the pressure in the case becomes low. Thus, the oil is returned to the compressor case through the first return pipe. According to this, the oil is reliably recovered from the other outdoor unit even when the compressor in which the pressure inside the case is high is running or stopped.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the air conditioner according to the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes an outdoor unit.
The outdoor unit 1 includes two outdoor units 7 and 8, and the outdoor units 7 and 8 include a gas pipe 2 and a liquid pipe 3.
Are connected, and indoor units 5 and 6 are connected in parallel to the inter-unit piping 4. The indoor units 5 and 6 each include an indoor electric expansion valve 9 and an indoor heat exchanger 10. The outdoor units 7 and 8 include the accumulator 18 and the compressor 1.
2 and 13, an oil separator 14, a four-way valve 15, an outdoor heat exchanger 16, and an outdoor electric expansion valve 17.

As apparent from FIG. 2, return pipes 19 are connected to the oil separators 14 of the outdoor units 7 and 8, respectively. These return pipes 19 are connected to a common oil return pipe 20.
The oil return pipe 20 is connected to each of the compressors 12 and 13 through a return pipe 21.

One of the compressors 12 is a compressor such as a rotary compressor which has a high pressure inside the case, and the other compressor 13 is a compressor such as a scroll which has a low pressure inside the case. Since the pressure in the case of the latter compressor 13 is always low, the return pipe 21 is directly connected to the case via the on-off valve 25.

On the other hand, the former compressor 12 has a high pressure inside the case during operation. Therefore, the return pipe 21 is connected to the on-off valve 26.
Through the first return pipe 22
Is connected directly to the case via a check valve 27 and a second return pipe 23 is provided with a reverse trap 28 for adding resistance to the flow.
Through the suction pipe 24 of the compressor 12.

Reference numeral 31 denotes a controller. When the amount of oil accumulated in the compressors 12 and 13 becomes unbalanced and one of the compressors runs short of oil, the controller 31 controls the other compressor. Operates to collect machine oil.

That is, the controller 31 controls the compressor 12,
13 and the on-off valve 2
When the oil level sensor 32 detects oil shortage in any one of the compressors 12 and 13 and the oil level sensor 32 detects the oil shortage,
The signal is output to the controller 31, the open / close valve on the compressor side where the oil shortage occurs is opened, and the oil on the other compressor side is collected.

In the compressor 13, since the pressure inside the case is always low, the oil is collected from the other outdoor unit 7 only by opening the on-off valve 25.

According to this embodiment, however, a feature is in control of recovering oil to the compressor 12 in which the pressure inside the case becomes high.

That is, the inside of the case of the compressor 12 has a high pressure during operation as described above. Therefore, the compressor 1
When the oil shortage occurs during operation 2 and the on-off valve 26 is opened, the pressure inside the case is high. The pressure is exceeded and is recovered from the suction pipe 24 to the compressor through the second return pipe 23.

When the oil is recovered while the compressor 12 is stopped, the pressure in the case becomes low when the compressor 12 is stopped. Therefore, when the on-off valve 26 is opened, the oil is discharged to the check valve 27 and the first valve 27.
Through the return pipe 22 of the compressor 12. At this time, since the oil is pressed there by the action of the reverse trap 28, it does not flow into the suction pipe 24 of the compressor 12.

According to this, during operation of the compressor 12, oil flows through the second return pipe 23 through the suction pipe 2 of the compressor 12.
4 and during the stop, the oil returns to the first return pipe 2
2. Since the oil is returned into the case of the compressor 12 after the pressure has been reduced through the check valve 27, even if the compressor 12 runs short of oil, it is possible to surely collect the oil from the other outdoor unit 8. it can.

Further, while the compressor 12 is stopped, the oil is returned to the case of the compressor 12 without returning to the suction pipe 24 of the compressor 12, so that when the compressor is restarted, the oil is returned to the inside of the compressor 12. Oil compression does not occur and the compressor 1
2 is well protected.

FIG. 3 shows another embodiment.

The outdoor unit 100 incorporates two compressors, a compressor 101 such as a rotary compressor which has a high pressure inside the case and a compressor 103 such as a scroll which has a low pressure inside the case. . In the latter compressor 103, since the pressure inside the case is always low, the return pipe 105
Through the case.

On the other hand, during operation of the former compressor 101, the pressure inside the case becomes high. Therefore, the return pipe 109 branches into two via the on-off valve 111, and then the first return pipe 113 is directly connected to the case via a check valve (or a solenoid valve) 115, and the second return pipe 113 is opened. The pipe 117 is connected to the suction pipe 121 of the compressor 101 via a reverse trap 119 for adding resistance to the flow.

The controller 123 controls the compressor 10
When the oil level sensor 125, 127 is connected to the open / close valves 107, 111, and one of the compressors 101, 103 is short of oil, and the oil level sensor detects it, the signal is sent to the controller. The oil is output to 123, and the on-off valve on the compressor side where the oil shortage has occurred is opened, and oil is collected from the oil separator 14.

In the compressor 103, since the pressure in the case is always low, the oil is recovered from the oil separator 14 only by opening the on-off valve 107.

On the other hand, in the compressor 101, the compressor 1
In the case 01, the pressure becomes high during operation as described above.
Therefore, when the oil shortage occurs during the operation of the compressor 101 and the on-off valve 111 is opened, the pressure inside the case is high, so the first return pipe 113 is blocked by the check valve 115, and the oil is Overcoming the trap 119, the second return pipe 11
7, the liquid is recovered from the suction pipe 121 to the compressor 101.

When the oil is recovered while the compressor 101 is stopped, the pressure inside the case becomes low when the compressor 101 is stopped.
And is collected in the case of the compressor 101 through the first return pipe 113. At this time, since the oil is pressed there by the action of the reverse trap 119, it does not flow into the suction pipe 121 of the compressor 101.

According to this, when the oil amount becomes unbalanced between the two compressors 101 and 103 having the common oil separator 14, the compressor 101 becomes high in the case.
On the other hand, the shortage of oil can be reliably recovered from the oil separator 14 even during operation or stop.

Although the present invention has been described based on one embodiment, the present invention is not limited to this.

For example, in FIG.
When the oil is collected in the case of the compressor 12 during the stop of the oil, the oil flows through the second return pipe 23 to the compressor 1.
So that the second return pipe 2 does not flow into the suction pipe 24 of the second return pipe 2.
3 may be provided with an on-off valve instead of the reverse trap 28.

[0031]

As is apparent from the above description, according to the present invention, in a compressor in which the pressure inside the case becomes high during operation, when the pressure inside the case becomes low (during stop), the pressure in the case becomes low. And a second return pipe for returning oil to the suction pipe of the compressor when the pressure inside the case is high (during operation). Even when a compressor having a high pressure inside the case, such as a rotary compressor, is at a high pressure or at a low pressure, oil can be reliably recovered from another compressor to the compressor.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of an air conditioner according to the present invention.

FIG. 2 is a refrigerant circuit diagram showing a main part in an enlarged manner.

FIG. 3 is a refrigerant circuit diagram showing another embodiment.

[Explanation of symbols]

 Reference Signs List 4 Unit piping 5, 6 Indoor unit 7, 8 Outdoor unit 12 Compressor with high pressure in case 13 Compressor with low pressure in case 20 Oil return pipe 22 First return pipe 23 Second return pipe 25, 26 On-off valve 27 Check valve 28 Reverse trap

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F25B 1/00 F25B 13/00

Claims (2)

(57) [Claims] 1. A plurality of outdoor units are connected in parallel to piping between units extending from an indoor unit, and the pressure inside a case of a compressor incorporated in each of the outdoor units is set to be different. In the air conditioner connected by a return pipe, a first return pipe that directly returns oil from the oil return pipe into the case of the high-pressure side compressor, and a second return pipe that returns oil to the suction pipe of the high-pressure side compressor. Oil is returned to the suction pipe through the second return pipe when the high-pressure side compressor is operating, and is returned into the case through the first return pipe when the compressor is stopped. An air conditioner comprising a control unit. 2. A compressor having a plurality of compressors connected in parallel and a common oil separator connected to a discharge pipe of these compressors, wherein the pressures in the casings of these compressors are set to be different. In the air conditioner, an oil return pipe for returning the oil separated by the oil separator to a compressor whose case is on the high pressure side, a first return pipe directly connected to the case of the high pressure side compressor, A second return pipe connected to the suction pipe of the high pressure side compressor, and while the high pressure side compressor is operating, returns oil to the suction pipe through the second return pipe and stops the compressor. An air conditioner comprising a control means for returning oil inside the case through a first return pipe.