JPS6215504Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention relates to a parallel compression type refrigeration system, and in particular, both when compressors are operated in parallel and when any compressor is operated independently. The present invention relates to a parallel compression type refrigeration system in which the lubricating oil level of each compressor is maintained at an appropriate level.

[Prior Art] FIG. 2 is a partial configuration diagram showing a conventional parallel compression type refrigeration system. In FIG. 2, the first compressor 1
is equipped with a suction chamber 103 and an oil reservoir chamber 104, and the suction chamber 103 and the oil reservoir chamber 104 are connected to the first
a crankcase 10 forming a container for a compressor 1;
1 is partitioned by partition walls 102.
The second compressor 2 has a suction chamber 203 and an oil reservoir chamber 204.
The suction chamber 203 and the oil reservoir chamber 20
4 is constructed by partitioning the inside of a crankcase 201 forming a container of the second compressor 2 with a partition wall 202. The first electric motor 105 has a stator winding 1
05a and an armature winding 105b, and is installed in the suction chamber 103 of the first compressor 1. Second
The electric motor 205 includes a stator winding 205a and an armature winding 205b, and has a suction chamber 2 of the second compressor 2.
It is installed on 03. first piston 106
is installed in the oil sump chamber 104 of the first compressor 1, and is made up of a part of the wall surface of the oil sump chamber 104.
A piston is moved within the cylinder 107 by the first electric motor 105. second piston 20
6 is installed in the oil reservoir chamber 204 of the second compressor 2, and is configured by a part of the wall surface of the oil reservoir chamber 204.
The piston is moved within the cylinder 207 by the second electric motor 205. By this piston movement of the first and second pistons 106, 206,
The refrigerant gas in the suction chambers 103, 203 flows into the cylinders 107, 2 through holes 108, 208, respectively.
07, and is discharged from the cylinders 107, 207 to the outside through the holes 109, 209. The first and second pressure equalizing holes 110 and 210 are provided in the partition walls 102 and 202, respectively, and are provided in the suction chamber 10.
3, 203 and the pressure in the oil reservoir chambers 104, 204 are equalized. First and second check valves 11
1 and 211 are provided to penetrate through the partition walls 102 and 202, respectively, and allow lubricating oil to pass only from the suction chambers 103 and 203 side to the oil reservoir chambers 104 and 204 side. The liquid separator 3 is provided on the suction side of the first and second compressors 1 and 2, and is connected to the suction pipe 4 from the evaporator (not shown).
A mixture of refrigerant and lubricating oil delivered through
The refrigerant is separated into a gas refrigerant and a mixture of liquid refrigerant and lubricating oil. The U-shaped tube 302 is installed in the liquid separator 3 so that the U-shaped bottom is connected to the lubricating oil accumulated at the bottom of the liquid separator 3, and the U-shaped bottom is connected to the lubricating oil accumulated at the bottom of the liquid separator 3. An oil return hole 301 is provided. One end of each of the first and second gas suction pipes 5 and 6 is connected to the suction chambers 103 and 203 of the first and second compressors 1 and 2, and the other end of each of the first and second gas suction pipes is connected to the main gas suction pipe. 7 to the discharge side end of the U-shaped pipe 302. One end of each of the first and second gas discharge pipes 8 and 9 is connected to the holes 109 and 209 of the first and second compressors 1 and 2, and the other end of each of the first and second gas discharge pipes 8 and 9 is connected to the main gas discharge pipe 10. via a condenser (not shown). The oil equalizing pipe 11 is
Oil reservoir chambers 104 and 20 of the first and second compressors 1 and 2
4 are connected to each other to equalize the oil levels in the oil reservoir chambers 104 and 204.

Next, the operation of this prior art will be explained. Now, the first
During the capacity control operation in which the compressor 1 is operated and the second compressor 2 is stopped, there is pressure loss due to flow path resistance from the first gas suction pipe 5 to the suction chamber 103. The pressure in the suction chamber 103 of the first compressor 1 during operation is the same as that of the second compressor 2 when it is stopped.
The pressure in the suction chamber 203 and the oil reservoir chamber 204 is inevitably lower than that in the suction chamber 203 and the oil reservoir chamber 204 . Further, since the oil reservoir chamber 104 and the oil reservoir chamber 204 are in communication with each other through the oil equalizing pipe 11, the pressure inside the suction chamber 103 is equal to the pressure in the oil reservoir chamber 104.
It's lower than the internal pressure. Therefore, the oil level in the suction chamber 103 is higher than the oil level in the oil reservoir chamber 104. That is, the oil level difference corresponding to the pressure difference between the suction chamber 103 and the oil reservoir chamber 104 is
Balance in a high position.

[Problems to be solved by the invention] Since the conventional device is configured as described above, when the piston 106 is operated in this balanced state, the lubricating oil in the oil reservoir chamber 104 is It flows into the suction chamber 103 from the pressure equalization hole 110 of No. 1 and is stored in the suction chamber 103. At the same time, the oil is supplied to the condenser (not shown) via the hole 108 → cylinder 107 → hole 109 → first gas discharge pipe 8 and main gas discharge pipe 10, so that The drawback was that the amount of lubricating oil decreased.

Furthermore, in both parallel operation in which the first and second compressors 1 and 2 are operated simultaneously, and capacity control operation in which either one of the first and second compressors 1 and 2 is operated. The lubricating oil stored at the bottom of the liquid separator 3 is sucked through the oil return hole 301 provided at the bottom of the U-shaped tube 302, and is transferred between the U-shaped tube 302, the main gas suction tube 7, and the first and second gas suction tubes. The suction chambers 10 of the first and second compressors 1 and 2 are connected via the gas suction pipes 5 and 6 of the second compressor.
He was repatriated on 3,203.

Therefore, the pipe diameter of the U-shaped pipe 302 is determined by the refrigerant gas velocity during capacity control operation, which is when only one of the first and second compressors 1 and 2 is operated. Therefore, during parallel operation, the refrigerant gas velocity passing through the U-shaped pipe 302 is twice that of the capacity control operation, increasing pressure loss. Therefore, during parallel operation, the pressure of the refrigerant gas sucked into the first and second compressors 1 and 2 decreases, resulting in a disadvantage that the refrigerating capacity decreases.

This idea was made to eliminate the drawbacks of the conventional ones as described above, and it is a parallel compression type refrigeration system that maintains a uniform oil level in each part under any operating condition and prevents a decrease in refrigeration capacity. The purpose is to obtain.

[Means for Solving the Problems] The parallel compression type refrigeration system according to this invention returns the gas refrigerant separated by the liquid separator to the first compressor. The lubricating oil separated by the gas suction pipe and the liquid separator is sucked and returned to the suction chamber of the second compressor through the U-shaped pipe installed in the liquid separator along with the gas refrigerant. a second gas suction pipe with smaller pressure loss; and an oil return pipe that returns the lubricating oil separated by the liquid separator to the oil sump chamber of the second compressor only when the first compressor is operating. ,
A second check valve is provided on the bulkhead of the second compressor and allows lubricating oil to flow from the suction chamber to the oil reservoir chamber. The compressor is provided with an oil equalizing pipe that allows lubricating oil to flow from the oil reservoir chamber of the second compressor to the oil reservoir chamber of the first compressor during operation. In other words, the U-shaped pipe of the liquid separator is
Connected only to the compressor suction pipe. Moreover, the suction pipe to the first compressor is independently connected to the upper part of the liquid separator.

[Function] In this invention, when only the first compressor is operated, the pressure on the first compressor side is lowered due to the pressure loss in the first gas suction pipe, and the second check valve and the oil equalizing pipe are closed. This makes the oil level uniform, and the lubricating oil in the liquid separator is returned from the oil return pipe to the first compressor via the second compressor. When only the second compressor is in operation, the oil equalizing pipe is closed and the lubricating oil in the liquid separator is sucked and returned from the second gas suction pipe together with the gas refrigerant, and the use of the U-shaped pipe is replaced by the second compressor. This is done only when the machine is in operation to prevent a drop in refrigeration capacity. Further, when the first and second compressors are operated, the oil equalizing pipe is opened to equalize the oil level in the same way as when the first compressor is operated.

[Example] An example of this invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a parallel compression type refrigeration system according to this invention. In the figure, the first compressor 1
is equipped with a suction chamber 103 and an oil reservoir chamber 104,
The suction chamber 103 and the oil reservoir chamber 104 are configured by partitioning the inside of the crankcase 101, which forms the container of the first compressor 1, with a partition wall 102. The first check valve 111 is provided in the partition wall 102 and is provided in the suction chamber 1
Only when the pressure in the oil reservoir chamber 104 becomes higher than the pressure in the oil reservoir chamber 104, the lubricating oil in the suction chamber 103 is caused to flow into the oil reservoir chamber 104. The second compressor 2 includes a suction chamber 203 and an oil reservoir chamber 204, and the suction chamber 203 and the oil reservoir chamber 204 are arranged inside the crankcase 201 that forms the container of the second compressor 2. ,
It is partitioned by a partition wall 202. The second check valve 211 is provided in the partition wall 202 and is provided in the suction chamber 2
Only when the pressure in the oil reservoir chamber 204 becomes higher than the pressure in the oil reservoir chamber 204, the lubricating oil in the suction chamber 203 is caused to flow into the oil reservoir chamber 204. First electric motor 105
includes a stator winding 105a and an armature winding 105b, and is installed in the suction chamber 103 of the first compressor 1. The second electric motor 205 includes a stator winding 205a and an armature winding 205b, and is installed in the suction chamber 203 of the second compressor 2. The first piston 106 is installed in the oil sump chamber 104 of the first compressor 1, and moves inside the first cylinder 107, which is made up of a part of the wall surface of the oil sump chamber 104.
The piston is moved by an electric motor 105. The second piston 206 is installed in the oil reservoir chamber 204 of the second compressor 2, and the second piston 206 moves inside the second cylinder 207, which is made up of a part of the wall surface of the oil reservoir chamber 204.
The piston is moved by an electric motor 205. Due to the piston movements of the first and second pistons 106 and 206, the refrigerant gas in the suction chambers 103 and 203 is sucked into the cylinders 107 and 207 through the holes 108 and 208, respectively, and
It is discharged from inside the cylinders 107, 207 to the outside via 209. first and second pressure equalizing holes 110,
210 is provided in the partition walls 102, 202, respectively, and is connected to the pressure in the suction chambers 103, 203 and the oil reservoir chamber 10.
Equalize the pressure in 4,204. Liquid separator 3
is provided on the suction side of the first and second compressors 1 and 2, and converts the mixture of refrigerant and lubricating oil sent from the evaporator (not shown) through the suction pipe 4 into gas. The refrigerant is separated into a mixture of liquid refrigerant and lubricating oil. The U-shaped tube 302 is installed in the liquid separator 3 so that the U-shaped bottom part is soaked in the lubricating oil collected at the bottom of the liquid separator 3; An oil return hole 301 for raising the oil is provided. The first gas suction pipe 5 is configured to be long, for example, to increase pressure loss, and one end thereof is connected to the suction chamber 103 of the first compressor 1.
The other end is connected to the upper end of the liquid separator 3. The second gas suction pipe 6 is configured to be short, for example, to reduce pressure loss, and one end thereof is connected to the suction chamber 203 of the second compressor 2, and the other end is connected to the discharge chamber 203 of the U-shaped pipe 302. Connected to the side ends. The first and second gas discharge pipes 8 and 9 each have one end connected to the hole 10 of the first and second compressor 1 and 2.
9 and 209, and the other end of each is connected to a condenser (not shown) via a main gas discharge pipe 10. The oil equalizing pipe 11 is connected between the oil reservoir chambers 104 and 204 of the first and second compressors 1 and 2, and is a third check that allows lubricating oil to pass only from the oil reservoir chamber 204 to the oil reservoir chamber 104 side. A valve 12 is provided. The oil return pipe 13 connects the bottom of the liquid separator 3 and the second compressor 2.
It is provided between the suction chambers 203 of. Solenoid valve 14
is provided in the oil return pipe 13, is closed when the second compressor 2 is in operation, and is opened when the second compressor 2 is stopped.

Next, the operation of this embodiment will be explained. Now, first,
During parallel operation when the second compressors 1 and 2 are operated, the refrigerant and lubricating oil returned from the evaporator (not shown) to the liquid separator 3 via the suction pipe 4 are as follows:
It is separated into a gas refrigerant and a mixture of liquid refrigerant and lubricating oil, and the mixture of liquid refrigerant and lubricating oil accumulates at the bottom of the liquid separator 3. The lubricating oil accumulated at the bottom is sucked into the U-shaped pipe 302 through the oil return hole 301, and together with the gas refrigerant in the upper part of the liquid separator 3, the lubricating oil is drawn into the U-shaped pipe 302 and the second
The gas is sucked into the suction chamber 203 of the second compressor 2 through the gas suction pipe 6 . In this case, since the first gas suction pipe 5 is longer than the second gas suction pipe 6 and is configured to have a large pressure loss, the suction chamber 1
The pressure relationship between 03, 203 and the oil reservoir chambers 104, 204 is as follows: suction chamber 103<oil reservoir chamber 104<
The order is oil reservoir chamber 204<suction chamber 203. Therefore, the lubricating oil sucked into the suction chamber 203 of the second compressor 2 passes through the second check valve 211 and enters the oil reservoir chamber 2.
04, and is also supplied to the oil reservoir chamber 104 through the oil equalizing pipe 11 and the third check valve 12.
Note that since there is a first check valve 111 between the suction chamber 103 and the oil reservoir chamber 104, the lubricating oil supplied to the oil reservoir chamber 104 does not flow into the suction chamber 103.
The oil reservoir chamber 104 provides lubrication.

Next, during the capacity control operation in which only the second compressor 2 is operated, the lubricating oil is sucked into the U-shaped pipe 302 through the oil return hole 301, and the gas refrigerant is It is also supplied to the suction chamber 203. At this time, since pressure loss occurs in the second gas suction pipe 6, the suction chamber 103 of the first compressor 1
The pressure of 204 and is in a separated state. Therefore, the lubricating oil supplied to the oil reservoir chamber 204 is used for lubrication.

Next, during capacity control operation in which only the first compressor 1 is operated, the lubricating oil and liquid refrigerant stay at the bottom of the liquid separator 3, and only the gas refrigerant flows from the top of the liquid separator 3. The gas is supplied to the suction chamber 103 of the first compressor 1 through the first gas suction pipe 5 . Further, the liquid refrigerant separated by the liquid separator 3 evaporates to become a gas refrigerant, and is supplied to the suction chamber 103 in the same manner as described above. In this state, since the solenoid valve 14 is open when the second compressor 2 is stopped, the lubricating oil accumulated in the liquid separator 3 is transferred to the oil return pipe 1.
3 into the oil reservoir chamber 204 of the second compressor 2. In this case, since a pressure loss occurs in the first gas suction pipe 5, each suction chamber 103, 2
03 and the oil reservoir chambers 104 and 204 are in the order of suction chamber 103<oil reservoir chamber 104<oil reservoir chamber 204<suction chamber 203, as described above. Therefore, the lubricating oil that has flowed into the oil reservoir chamber 204 is transferred to the suction chamber 203 via the second check valve 211 and to the oil reservoir via the oil equalizing pipe 11 and the third check valve 12, as described above. Room 104
and is used for lubrication.

Further, the pipe diameter of the U-shaped pipe 302 of the oil separator 3 is determined only by the capacity of the second compressor 2, and
Since only gas refrigerant is supplied to the first compressor 1 from the upper part of the oil separator 3, even when the first and second compressors 1 and 2 are operated in parallel, the U-shaped pipe 3
The pressure loss of 02 is exactly the same as when one second compressor 2 is operated, and the pressure loss is small.

[Effect of the idea] This idea is structured as above, so
When only the first compressor 1 is operating, and when the first and second compressors 1 and 2 are operating, the lubricating oil is separated in the liquid separator 3, and after flowing into the second compressor 2. , is supplied to the first compressor 1, and when only the second compressor 2 is in operation, the third check valve 12 provided in the oil equalizing pipe 11 is used to supply the first and second compressors 1. , 2, the oil level in the oil reservoir chambers 104, 204 will not drop under any operating conditions, preventing abnormalities in the sliding parts of the first and second compressors 1, 2. No wear or burnout accidents occur. Moreover, since the pressure loss due to the U-shaped pipe 302 of the liquid separator 3 can be reduced, a decrease in the refrigerating capacity and a decrease in the coefficient of performance can be prevented, and economical operation can be achieved.

As described above, this invention has the effect of preventing abnormal wear and burnout of the compressor and enabling economical operation.

[Brief explanation of the drawing]

FIG. 1 is a partial configuration diagram showing an embodiment of a parallel compression type refrigeration system according to this invention, and FIG. 2 is a partial configuration diagram showing a conventional parallel compression type refrigeration system. In the figures, the same parts in each figure are given the same reference numerals, and 1 and 2 are the first and second compressors, 101,
201 is a crankcase, 102, 202 are partition walls, 103, 203 are suction chambers, 104, 204 are oil reservoir chambers, 111, 211 are first and second check valves,
3 is a liquid separator, 301 is an oil return hole, 302 is a U-shaped pipe, 5 and 6 are first and second gas suction pipes, 11 is an oil equalizing pipe, 12 is a third check valve, 13 is an oil return tube, 1
4 is a solenoid valve.

Claims (1)

[Scope of utility model registration request] First and second compressors each having a structure in which the inside of the crankcase is divided into a suction chamber and an oil sump chamber by partition walls, and a gas refrigerant compressor provided on the suction side of the first and second compressors. A liquid separator having a U-shaped pipe provided at a U-shaped bottom with an oil return hole for separating lubricating oil and sucking up lubricating oil accumulated at the bottom, an upper part of the liquid separator and the first compressor. A first gas suction pipe with a larger pressure loss that connects to the suction chamber of the machine, the above-mentioned U
a second gas suction pipe with lower pressure loss that connects the discharge side end of the double pipe and the suction chamber of the second compressor; first and second check valves that allow lubricating oil to pass from the suction chamber side to the respective oil reservoir chambers; an oil equalizing pipe having a third check valve for passing lubricating oil from the oil sump chamber side of the compressor to the oil sump chamber side of the first compressor; a bottom portion of the suction chamber of the first compressor and the liquid separator; A parallel compression type refrigeration system comprising: an oil return pipe connecting the oil return pipe; and a solenoid valve provided in the oil return pipe, which is closed when the second compressor is in operation and opened when the second compressor is stopped.