JPH0138196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to simultaneous parallel operation of a plurality of refrigerant compressors connected in parallel with each other, or one side operation of one of the plurality of refrigerant compressors. The present invention relates to a parallel compression type refrigeration system in which the oil level of lubricating oil in a refrigerant compressor is always maintained in any case.

Conventionally, the device shown in FIG. 1 has been known as this type of device. In FIG. 1, 1 and 2 are semi-hermetic first and second refrigerant compressors, and the crankcases 101 and 2 of the first and second refrigerant compressors 1 and 2,
Inside 201, motor A is connected by partition walls 102, 202.
It is partitioned into suction chambers 103, 203 that accommodate the compression element B, and oil reservoir chambers 104, 204 that accommodate the compression element B.

Pressure equalizing holes 10 are provided at predetermined positions in the partition walls 102 and 202.
5,205 are provided. In addition, this partition wall 1
Oil equalizing check valves 106, 206 are installed in oil level equalizing holes provided at predetermined positions of 02, 202. The oil equalizing check valves 106, 206 are configured to allow the flow of lubricating oil only from the suction chambers 103, 203 to the oil reservoir chambers 104, 204.

In the suction chamber 103 of the first refrigerant compressor 1, a first
The first gas suction pipe 3 is connected to the evaporator (not shown) of the refrigeration cycle.
It is connected to a suction pipe 5 connected to.

Further, 4 is a suction pipe 2 of the second refrigerant compressor 2.
The second gas suction pipe connected to the suction pipe 5
The gas suction pipe 4 is configured to be long or thin so that the piping resistance of the gas suction pipe 4 is greater than the piping resistance of the first gas suction pipe 3.

The gas discharge pipe 6 of the first refrigerant compressor 1 and the gas discharge pipe 7 of the second refrigerant compressor 2 are connected in parallel to a high-pressure pipe 8 connected to a condenser (not shown) of the refrigeration cycle.

The oil reservoir chamber 104 of the first refrigerant compressor 1 and the second
The oil reservoir chambers 204 of the refrigerant compressors 2 are connected to each other by an oil equalizing pipe 9, and an oil equalizing pipe check valve 10 is provided in the middle of the oil equalizing pipe 9. This allows lubricating oil and refrigerant gas to flow only from the compressor 1 to the second refrigerant compressor 2.

Next, the operation will be explained. When the first and second refrigerant compressors 1 and 2 are in operation, the first refrigerant is compressed due to the difference in piping resistance between the suction pipes 3 and 4 of the first and second refrigerant compressors 1 and 2. The relationship between the operating pressures of the compressor 1 and the second refrigerant compressor 2 is (pressure in the suction chamber 103 of the first refrigerant compressor 1) - (pressure in the suction chamber 203 of the second compressor 2) = approximately 100~ It is 400mmAq.

Further, normally, oil containing about 0.5% of the refrigerant circulation amount returns to the first and second refrigerant compressors 1 and 2 together with the refrigerant gas that has evaporated inside the suction pipe 5 of the refrigerant cycle.

At this time, the refrigerant gas is separated into lubricating oil and gas by the separating means 501, and most of this lubricating oil flows from the suction pipe of the first refrigerant compressor 1 due to the influence of gravity.
It flows into the suction chamber 103 of the first refrigerant compressor 1.

Blow-by gas flows into the oil reservoir chamber 104 of the first refrigerant compressor 1 from the compression element B, and the oil reservoir chamber 104
pressure is increasing. When there is no second refrigerant compressor 2, there is a pressure equalization hole 10 between the suction chamber 103 and the oil reservoir chamber 104.
Although the pressure is equalized by 5, there is normally a pressure difference of 10 to 50 mmAq, and the oil reservoir chamber 104 side is higher.

Due to the pressure difference between the suction chambers, this blow-by gas passes through the oil equalizing pipe 9 to the oil reservoir chamber 20 of the second refrigerant compressor 2.
4 and enters the suction chamber 203 through the pressure equalization hole 205 together with the blow-by gas from the compression element B of the second refrigerant compressor 2.

The pressure difference between the suction chambers 103 and 203 is affected by the amount of refrigerant circulation, and when the evaporation temperature is low and the amount of refrigerant circulation is small, the pressure difference becomes small.

On the other hand, blow-by gas is affected by the compression ratio and the amount of circulation, and is proportional to the compression ratio and proportional to the amount of circulation, so the absolute amount of blow-by gas is almost constant regardless of the evaporation temperature. Therefore, the oil equalizing pipe resistance due to the passage of blow-by gas is constant, and the suction chamber 103,
When the pressure difference between the refrigerant compressors 1 and 203 becomes small, the blow-by gas of the first refrigerant compressor 1 cannot be treated due to the oil equalizing pipe resistance, and is treated only by the pressure equalizing holes 105 of the first refrigerant compressor 1. Therefore, the pressure difference between the suction chamber 103 and the oil reservoir chamber 104 of the first refrigerant compressor 1 is higher on the oil reservoir chamber 104 side, and the lubricating oil returned to the suction chamber 103 has a head difference corresponding to the pressure difference. This will cause it to accumulate in the suction chamber 103 and reach the lower part of the rotor of the motor element.

Next, when only the first refrigerant compressor 1 is operated, the refrigerant gas and lubricating oil flow from the suction pipe 5 into the suction chamber 103 via the suction pipe 3 of the first refrigerant compressor 1. During this time, the pressure in the suction chamber 103 of the first compressor 1 decreases by about 400 mmAq due to pressure loss in the piping.

On the other hand, since the oil equalizing pipe 9 is provided with a pressure equalizing pipe check valve 104 that operates at about 100 mmAq, the oil reservoir chamber 104 of the second refrigerant compressor 2 to the first refrigerant compressor 1
As described above, the pressure in the oil reservoir chamber 104 becomes the same as in the case of two-unit operation at a low evaporation temperature due to blow-by gas.

Next, when only the second refrigerant compressor 2 is operated, the refrigerant gas is transferred from the suction pipe 5 to the second refrigerant compressor 2.
Flows into the suction chamber 203 from the suction pipe 4 . During this time, the pressure will drop by approximately 600mmAq due to pressure loss in the piping. Further, the pressure in the oil reservoir chamber 204 is also reduced by the action of the pressure equalizing hole 205.

On the other hand, lubricating oil is supplied from the suction pipe 5 to the suction pipe 3 of the first refrigerant compressor 1, to the suction chamber 103, and to the oil equalizing check valve 10.
However, since the first refrigerant compressor 1 is not operating, the pressure loss in the suction pipe 3 is extremely small. The pressure P104 and the pressure P204 of the oil reservoir chamber 204 of the second refrigerant compressor 2 are P104
> P204, and a part of the lubricating oil accumulated in the oil reservoir chamber 104 of the first refrigerant compressor 1 is supplied to the oil reservoir chamber 204 of the second refrigerant compressor 2 due to the pressure difference, and the operation is performed normally. Can be done.

As mentioned above, in conventional parallel compression refrigeration equipment,
If the evaporation temperature is low when operating two refrigerant compressors, the lubricating oil that has returned to the suction chamber of the first refrigerant compressor will have difficulty reaching the oil reservoir chamber, and the oil supply to the oil reservoir chamber of the second refrigerant compressor will become difficult. There was a risk that this would lead to oil shortage and abnormal wear of the sliding parts.

Furthermore, the lubricating oil accumulated in the suction chamber of the first refrigerant compressor was splashed up by the rotor, causing oil to rise.

This invention was made to eliminate the above-mentioned conventional drawbacks, and by using a compressor having a structure in which the blow-by gas treatment of the first refrigerant compressor is performed by the first refrigerant compressor, the oil level can be reduced. It is an object of the present invention to provide a parallel compression type refrigeration system that can ensure stability.

Hereinafter, one embodiment of the parallel compression type refrigeration system of the present invention will be described with reference to the piping diagram shown in FIG. In this Fig. 2, in order to avoid duplication, the same parts as in Fig. 1 are given the same reference numerals and their explanations are omitted.
I will focus on the parts that differ from the diagram.
In FIG. 2, reference numeral 107 is a suction chamber on the compression element B side, which is separated from the suction chamber 103 side in which the motor is housed by a partition wall 102.

Further, 109 is a suction hole that communicates the suction chamber 103 with the suction chamber 107 on the compression element B side, and serves as a throttle device.

Suction chamber 107 and oil reservoir chamber 10 on this compression element B side
4 is designed to equalize the pressure in the pressure equalizing hole 108. The other configurations are the same as in FIG. 1.

Next, the operation of the parallel compression type refrigeration system of the present invention configured as described above will be explained. When operating two units, the return of lubricating oil from the suction pipe 5 is the same as before, but the refrigerant gas that has flowed into the suction chamber 103 passes through the suction hole 109 and flows into the suction chamber 107 on the compression element B side. Enter B. First refrigerant compressor 1
Due to the pressure loss when the refrigerant gas passes through the suction hole 109, the suction chamber 107 on the compression element side becomes the suction chamber 1.
It is more than 100mmAq lower than 03.

In addition, since the blow-by gas in the oil reservoir chamber 104 is discharged from the suction chamber 107 on the compression element side through the pressure equalization hole 108, most of the blow-by gas is discharged by discharging it to the lowest pressure location. .
Therefore, the pressure relationship among the oil reservoir chamber 104, the suction chamber 103, and the suction chamber 107 on the compression element side is as follows: Pressure in the suction chamber 107 on the compression element side≦Pressure in the oil reservoir chamber 104<Pressure in the suction chamber 103. The lubricating oil that has flowed into the suction chamber 103 enters the oil reservoir chamber 104.

Since the oil sump chamber 104 of the first refrigerant compressor 1 and the oil sump chamber 204 of the second refrigerant compressor 2 are communicated with each other by the oil equalizing pipe 9, the oil sump Since there is also a pressure difference between the chambers 104 and 204, and the blow-by gas of the first refrigerant compressor 1 is processed within the first refrigerant compressor 1, the pressure difference between the suction chambers 103 and 203 becomes small. hand,
Even if the pressure difference between the oil reservoir chambers 104 and 204 becomes small, the oil equalizing pipe 9 only moves oil, so the pressure relationship between the suction chambers 103 and 203 and the oil reservoir chambers 104 and 204 is always the same as that of the second refrigerant compression. The pressure in the suction chamber 203 of the machine<the pressure in the oil sump 204 of the second refrigerant compressor<the pressure in the oil sump chamber 104 of the first refrigerant compressor<the pressure in the suction chamber 103 of the first refrigerant compressor. The lubricating oil returned to the suction chamber 103 of the first refrigerant compressor 1 is supplied to the first and second oil reservoir chambers 104 and 204.

Next, when only the first refrigerant compressor 1 is operated, as in the past, the first refrigerant compressor 1 is operated alone, so the oil sump chamber 104 is operated as described for the two-unit operation.
The pressure in the suction chamber 103 is always lower than that in the suction chamber 103, and lubricating oil is supplied to the oil reservoir chamber 104. Note that the case where only the second refrigerant compressor 2 operates is the same as the conventional case.

As described above, according to the parallel compression type refrigeration system of the present invention, when two units are operated, the blow-by gas of the first refrigerant compressor is processed in the first refrigerant compressor, so that the first refrigerant compressor is always The pressure in the oil sump chamber of the second refrigerant compressor is lower than that in the first suction chamber, and the pressure between the oil sump chambers in the second refrigerant compressor is lower, ensuring that the lubricating oil returned to the first suction chamber is lower. The lubricating oil is supplied to each oil storage chamber, which not only prevents abnormal wear of sliding parts due to lack of oil, but also prevents lubricating oil from accumulating in the suction chamber of the first refrigerant compressor, causing oil to be splashed up by the rotor. No more oil build-up due to this. Accordingly, the oil level of the lubricating oil in the refrigerant compressor can always be maintained at an appropriate level.

[Brief explanation of drawings]

FIG. 1 is a piping diagram showing a conventional parallel compression refrigeration system, and FIG. 2 is a piping diagram showing an embodiment of the parallel compression refrigeration system of the present invention. DESCRIPTION OF SYMBOLS 1... First refrigerant compressor, 2... Second refrigerant compressor, 3-5... Suction pipe, 9... Oil equalizing pipe, 10... Check valve, 101, 201... Crank case, 102,
202...Partition wall, 103, 203...Suction chamber, 10
4,204...Oil sump room, 105,205,108...
Equalizing pressure hole, 106, 206... Oil equalizing check valve, 107...
Suction chamber on compression element side, 109...suction hole. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A first and second oil equalizing check valve that allows lubricating oil to flow only from the suction chamber side to the oil reservoir chamber side at a predetermined position of a partition wall that divides the inside of the crankcase into a suction chamber side and an oil reservoir chamber side. a second refrigerant compressor; a first gas suction pipe whose one end is connected to the suction chamber of the first refrigerant compressor and whose other end is connected to the lower part of the suction pipe of the refrigeration cycle; the second refrigerant compressor; A second refrigerant compressor, which is connected to the suction chamber of the refrigerant compressor, and whose other end is connected to the upper part of the suction pipe of the refrigeration cycle, and which has a piping resistance greater than the piping resistance of the gas suction pipe of the first refrigerant compressor.
a gas suction pipe, and a check valve that communicates the oil reservoir chambers of the first and second refrigerant compressors with each other and allows at least lubricating oil to flow only from the first refrigerant compressor to the second refrigerant compressor. an oil equalizing pipe having an oil equalizing pipe disposed in the first refrigerant compressor in the middle;
A parallel compression type refrigeration system comprising means for forcibly discharging the blow-by gas in the oil reservoir of the refrigerant compressor to the suction chamber and lowering the pressure in the oil reservoir to be lower than the pressure in the suction chamber.