JPH0217190Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] This invention is capable of controlling the oil level either during parallel operation of refrigerant compressors connected in parallel to each other or during independent operation of any compressor. This invention relates to a parallel compression type refrigeration system that is properly maintained.

[Prior art]

FIG. 1 is a piping diagram of a conventional parallel compression type refrigeration system disclosed in Japanese Patent Application Laid-Open No. 58-77184. In the figure, 1 and 2 are semi-hermetic first and second refrigerant compressors, for example. 101 is a crankcase of the first refrigerant compressor 1, 201 is a crankcase of the second refrigerant compressor 2, 102 is a drive motor that drives the first refrigerant compressor 1, and 202 is a drive motor of the second refrigerant compressor 1. A drive motor that drives the refrigerant compressor 2; 103, a suction chamber that houses the drive motor 102 of the first refrigerant compressor 1; 203, a suction chamber that houses the drive motor 202 of the second refrigerant compressor 2; 104 is the first
A compression element such as a piston of the refrigerant compressor 1, 204
is a compression element such as a piston of the second refrigerant compressor 2,
105 is an oil sump chamber that accommodates the compression element 104 of the first refrigerant compressor 1, 205 is an oil sump chamber that accommodates the compression element 204 of the second refrigerant compressor 2, and 106 is the first
206 is a partition wall that partitions the suction chamber 103 and oil reservoir chamber 105 of the second refrigerant compressor 1;
107 is an equalizing differential pressure valve provided at a predetermined position on the partition wall 106 of the first refrigerant compressor 1; 207 is an equalizing differential pressure valve provided at a predetermined position on the partition wall 206 of the second refrigerant compressor 2; Both differential pressure valves close only when the pressure in the suction chamber is significantly lower than the pressure in the oil reservoir chamber, such as during startup. 108 is provided at a predetermined position on the partition wall 106 of the first refrigerant compressor 1;
From the suction chamber 103 of the refrigerant compressor 1 to the oil reservoir chamber 105
An oil equalizing check valve 208 is provided at a predetermined position on the partition wall 206 of the second refrigerant compressor 2 and allows oil to flow from the suction chamber 203 of the second refrigerant compressor 2 to the adjacent oil sump. An oil equalizing check valve that allows oil to flow only to the chamber 205; 109 is the lubricating oil level of the first refrigerant compressor 1; 209 is the lubricating oil level 3 of the refrigerant compressor 2; A first pipe 4 branches vertically downward from the pipe end of the suction pipe 3 of the refrigeration cycle and communicates with the suction chamber 103 of the first refrigerant compressor 1.
5 is the suction pipe 3 of the refrigeration cycle.
This is a second gas suction pipe that branches vertically upward from the pipe end and communicates with the suction chamber 203 of the second refrigerant compressor 2, and [pressure loss of the second gas suction pipe 5]≧[first gas suction pipe] The piping dimensions, etc. are set so as to equalize the pressure loss of the gas suction pipe 4.

Reference numeral 6 denotes a branching part where the pipe end of the suction pipe 3 of the refrigeration cycle branches at right angles to the first gas suction pipe 4 and the second gas suction pipe 5, and 7 denotes a branch part of the first refrigerant compressor 1. A gas discharge pipe, 8 a gas discharge pipe of the second refrigerant compressor 2, 9 a discharge gas passing through the gas discharge pipe 7 of the first refrigerant compressor 1 and a gas discharge pipe of the second refrigerant compressor 2; A high pressure pipe of the refrigeration cycle is connected to the discharge gas passing through 8, and 10 communicates the oil reservoir chamber 105 of the first refrigerant compressor 1 and the oil reservoir chamber 205 of the second refrigerant compressor 2. Oil equalizing pipe, 11
is a check valve that is installed in this oil equalizing pipe and allows oil to flow only in the direction from the first refrigerant compressor 1 to the second refrigerant compressor 2.

FIG. 2 is a detailed sectional view showing an enlarged branch part 6 where the suction pipe 3 of the refrigeration cycle in a conventional device branches at right angles into a first gas suction pipe 4 and a second gas suction pipe 5. . Normally, a T-joint or the like is used for this part, but 601 is a continuous arc-shaped branch inner wall surface so that the suction pipe 3 of the refrigeration cycle branches into the first gas suction pipe 4 and the second gas suction pipe 5. It is.

401 is an inner wall surface of the first gas suction pipe 4.

In FIGS. 1 and 2, solid line arrows (←) indicate the direction of flow of refrigerant gas, and broken line arrows (←--) indicate the direction of flow of lubricating oil.

The conventional parallel compression type refrigeration system is configured as described above, and [pressure loss of the second gas suction pipe 5]≧[first
Since the piping dimensions, etc. are determined so that the pressure loss of the gas suction pipe 4 is
When operating in parallel, the pressure in the suction chamber 203 of the second refrigerant compressor 2, and therefore the pressure equalizing differential pressure valve 20
7, the pressure in the oil reservoir chamber 205 is lower than the pressure in the suction chamber 103 of the first refrigerant compressor 1. Therefore, the lubricating oil that passes through the first gas suction pipe 4 and is returned to the suction chamber 103 The oil is returned to the oil sump chamber 105 of the first refrigerant compressor 1 through the oil equalizing check valve 108, and then is returned to the oil sump of the second refrigerant compressor 2 via the oil equalizing pipe 10 and the check valve 11. The oil is returned to the chamber 205. At this time, since the pressure in the oil reservoir chamber 205 of the second refrigerant compressor 2 is higher than the pressure in the adjacent suction chamber 203, the lubricating oil passes through the second gas suction pipe 5 and is transferred to the second refrigerant compressor 2. When the oil flows into the suction chamber 203, it does not flow into the adjacent oil reservoir chamber 205, and the oil flows into the second refrigerant compressor 2.
The refrigerant is accumulated in the suction chamber 203 of the refrigerant gas, and is in a state where it can be easily sucked into the second refrigerant compressor 2 together with the refrigerant gas in a liquid state.

For this reason, an oil separator should not be installed on the gas discharge side of the refrigerant compressor because oil compression may cause damage to the valve part, secondary damage to the bore, valve plate, etc., or an increase in the amount of oil coming up. In this case, there was a risk that an appropriate amount of lubricating oil would flow into the evaporator (not shown), resulting in a decrease in the refrigerating capacity.

In addition, since the total amount of lubricating oil in the refrigeration cycle is constant, the amount of oil corresponding to the total amount of oil accumulated in the suction chamber 203 of the second refrigerant compressor 2 and the amount of excess oil However, the amount of oil in the oil reservoir chamber 105 of the first refrigerant compressor 1 and the oil reservoir chamber 205 of the second refrigerant compressor 2 decreases, and the sliding parts in the refrigerant compressor are abnormally worn or burnt out due to insufficient supply of lubricating oil. There was a risk of an accident.

Next, when the first refrigerant compressor 1 operates independently, the pressure in the oil reservoir chamber 205 of the second refrigerant compressor 2 is the pressure in the suction chamber 103 of the first refrigerant compressor 1;
Therefore, the pressure is higher than the pressure in the oil reservoir chamber 105 of the first refrigerant compressor 1 through the pressure equalization differential pressure valve 107 .

As a result, the check valve 11 is closed, so that the pressure in the oil reservoir chamber 105 of the first refrigerant compressor 1 becomes equal to the pressure in the adjacent suction chamber 103. The lubricating oil returned to the chamber 103 is returned to the adjacent oil reservoir chamber 105, and an appropriate oil level is maintained.

In addition, when the second refrigerant compressor 2 operates independently, the pressure in the suction chamber 203 of the second refrigerant compressor 2 is higher than when the first and second refrigerant compressors 1 and 2 are operated in parallel. As a result, the pressure in the oil reservoir chamber 205 of the second refrigerant compressor 2 through the pressure equalizing differential pressure valve 207 becomes lower than the pressure in the oil reservoir chamber 105 of the first refrigerant compressor 1. The oil is returned to the oil reservoir chamber 205 of the second refrigerant compressor 2 via the suction chamber 103 and oil reservoir chamber 105 of the first refrigerant compressor 1 , further through the oil equalizing pipe 10 and check valve 11 .

However, since the pressure in the oil reservoir chamber 205 of the second refrigerant compressor 2 is higher than the pressure in the adjacent suction chamber 203, the lubricating oil passes through the second gas suction pipe 5.
When the oil flows into the suction chamber 203 of the second refrigerant compressor 2, the oil is not returned to the oil reservoir chamber 205 of the second refrigerant compressor 2, and the amount of oil in the suction chamber 203 increases, and the oil is mixed with refrigerant gas. The lubricating oil is easily inhaled in liquid form.
As a result, an excessive amount of oil rises, resulting in damage to the valve part due to oil compression, damage to the cylinder wall, valve plate, etc., or if an oil separator is not installed in the gas discharge pipe of the refrigerant compressor. On the other hand, the oil sump chamber 205 of the second refrigerant compressor 2 causes a decrease in refrigerating capacity due to an excessive amount of lubricating oil flowing into the evaporator (not shown).
This also reduces the amount of oil in the oil reservoir chamber 105 of the first refrigerant compressor 1, resulting in insufficient oil supply to the sliding parts of the second refrigerant compressor 2 during operation, and abnormal wear of the sliding parts. , or cause burn-in accidents. The same accident as described above will occur in the first refrigerant compressor 1 as well, due to insufficient oil supply to the sliding parts at the next start-up.

As described above, whether the first and second refrigerant compressors 1 and 2 are operating in parallel or any compressor is operating independently, lubricating oil is supplied to the first gas suction pipe. 4 to the oil reservoir chamber 105 of the first refrigerant compressor 1 or the oil reservoir chamber 20 of the second refrigerant compressor 2
However, the amount of returned oil is mixed with the discharged refrigerant gas and sent to the gas discharge pipe 7 of the first refrigerant compressor 1 and the gas discharge pipe 8 of the second refrigerant compressor 2.
The oil storage chambers 105 and 2 of the first and second refrigerant compressors 1 and 2 are
This means that the oil amount of 05 is ensured.

However, as mentioned above, when the first and second refrigerant compressors 1 and 2 are operating in parallel, and when the second refrigerant compressor 2 is operating independently, some of the lubricating oil It is attracted by the gas flow flowing into the second gas suction pipe 5 and flows into the suction chamber 203 of the second refrigerant compressor 2 . That is, in the conventional parallel compression type refrigeration system, as shown in FIG.
The branch inner wall surface 601 of the branch part 6 that branches into two forms a uniform, continuous, and smooth arc, and the suction gas flows through an accurator or evaporator (not shown).
Since the gas velocity required for returning the lubricating oil to the refrigerant compressor from
01 and the second gas inlet pipe 5 via the second gas suction pipe 5.
The refrigerant flows into the suction chamber 203 of the refrigerant compressor 2. Second
As described above, the lubricating oil that has flowed into the suction chamber 203 of the second refrigerant compressor 2 does not flow into the adjacent oil reservoir chamber 205.
As a result, damage to the valve part due to excess oil rising, damage to the cylinder wall and valve plate, or excessive amount of lubricating oil if an oil separator is not installed on the discharge side of the refrigerant compressor. flows into the evaporator (not shown), resulting in a decrease in refrigerating capacity. On the other hand, the absolute amount of oil in the oil reservoir chambers 105 and 205 of the first and second refrigerant compressors 1 and 2 is insufficient, resulting in a shortage of lubricating oil supply.
This can lead to accidents such as abnormal wear or seizure of the sliding parts within the refrigerant compressor.

[Summary of the idea]

This invention was made with the purpose of improving this problem, and in a parallel compression type refrigeration system in which refrigerant compressors are connected in parallel, the first refrigerant compressor extends vertically, and gas passes through the first refrigerant compressor. At the branch point where the second gas suction pipe that communicates from the first gas suction pipe to the second refrigerant compressor branches, the open end of the second gas suction pipe is connected to the outward bell mouth of the first gas suction pipe. By protruding inward from the bellmouth-shaped inner wall surface of the insertion port, almost no lubricating oil returning from the refrigeration cycle suction pipe is allowed to flow into the second gas suction pipe, and most of the lubricating oil is diverted to the second gas suction pipe. The lubricating oil that has passed through the first gas suction pipe is returned to the first refrigerant compressor and further to the second refrigerant compressor, so that the lubricating oil that has passed through the first gas suction pipe is returned to the first and second refrigerant compressors. This system ensures that the amount of oil in the refrigerant compressor is maintained, and the lubricating function of the refrigerant compressor can be maintained, preventing abnormal wear and seizure of sliding parts in the refrigerant compressor due to lack of oil supply, unlike conventional devices. In addition, the lubricating oil returning from the refrigeration cycle suction pipe is prevented from flowing into the second gas suction pipe unlike in conventional equipment, so that the second refrigerant compressor Since lubricating oil does not accumulate, damage to the valve part due to oil compression,
This does not cause malfunctions such as damage to the cylinder wall or valve plate, and there is no excessive amount of oil coming up, so it is possible to prevent a decrease in the refrigerating capacity due to an excessive amount of lubricating oil flowing into the evaporator.

[Example of idea]

FIG. 3 is a piping diagram showing an embodiment of this invention.
209 are exactly the same as the above-mentioned conventional device.

In addition, the solid line arrow (←) in FIG. 3 and the following FIGS. 4 to 6 indicates the direction of flow of refrigerant gas, and the broken line arrow (←--) indicates the direction of flow of lubricating oil.

Reference numeral 4 designates a vertically arranged first gas suction pipe that communicates the refrigerant compressor side pipe end of the suction pipe 3 of the refrigeration cycle with the suction chamber 103 of the first refrigerant compressor 1. For example, they may be arranged one above the other. Reference numeral 5 designates a second gas suction pipe that branches horizontally from the straight part of the first gas suction pipe 4 and communicates with the suction chamber 203 of the second refrigerant compressor 2, similar to the conventional parallel compression type refrigeration system. The pipe dimensions, etc. are determined so that [pressure loss in the second gas suction pipe 5]≧[pressure loss in the first gas suction pipe 4].

Reference numeral 12 denotes a branch portion where the second gas suction pipe 5 branches horizontally from the vertical or oblique straight portion of the first gas suction pipe 4.

FIG. 4 is an enlarged detailed sectional view of the branch portion 12, in which 401 is the inner wall surface of the first gas suction pipe, 501 is the open end of the second gas suction pipe 5,
502 is a protruding portion where the open end 501 of the second gas suction pipe 5 protrudes from the bellmouth-shaped inner wall surface 1202;
Reference numeral 1201 indicates an outward bellmouth insertion port provided in the vertical portion of the first gas suction pipe 4; 1202 indicates a bellmouth-shaped inner wall surface of the outward bellmouth insertion port;
203 is the bellmouth-shaped inner wall surface 1202 and the second
This is a circularly continuous slit that intersects with the cylindrical surface of the gas suction pipe 5.

In the parallel compression type refrigeration system configured as described above, when the first and second refrigerant compressors 1 and 2 operate in parallel, and when the second refrigerant compressor 2 operates independently, When the lubricating oil returning to the refrigerant compressor side through the inner wall of the suction pipe 3 of the cycle reaches the inner wall surface 401 of the first gas suction pipe 4, the force of gravity acting vertically downward, the refrigerant gas flow, and the The behavior of the lubricating oil is controlled by the attractive force caused by the friction generated between the lubricating oil and the lubricating oil.In the embodiment of this invention, as shown in FIG. At the bellmouth-shaped insertion port 1201, the open end 501 of the second gas suction pipe 5 is connected to the first
Since the second gas suction pipe 5 is horizontally branched and connected by protruding inward from the inner wall surface 401 of the gas suction pipe 4, the gas velocity flowing into the second gas suction pipe 5 is lower than that of the conventional device. However, among the lubricating oil flowing down the inner wall surface 401 of the first gas suction pipe 4, the lubricating oil that has flowed into the bellmouth-shaped inner wall surface 1202 of the outward bellmouth insertion port 1201 is transferred to the second gas suction pipe 4. There is no attractive force due to the gas flow that would pull the tube back to the open end 501 and flow into the second gas suction tube 5.

Therefore, the force acting on the lubricating oil that has flowed into the bellmouth-shaped inner wall surface 1202 is overcome by gravity, flows down through the cylindrical surface of the second gas suction pipe 5 or the bellmouth-shaped inner wall surface 1202, and flows down to the first The refrigerant will flow down only in the direction of the suction chamber 103 of the refrigerant compressor 1.
Therefore, almost all of the lubricating oil returning through the suction pipe 3 of the refrigeration cycle passes through the first gas suction pipe 4 and flows into the suction chamber 103 of the first refrigerant compressor 1. In other words, the second gas suction pipe 5
Almost no lubricating oil flows into the suction chamber 203 of the refrigerant compression 2.

Unless the lubricating oil sent out with the discharge gas of the refrigerant compressor is returned to the oil sump chamber of the operating refrigerant compressor, it will lead to insufficient lubrication of the sliding parts. The lubricating oil return path of the embodiment is exactly the same as the lubricating oil return path of the conventional device described above, except that a portion of the lubricating oil flows into the second gas suction pipe. When the refrigerant compressors 1 and 2 operate in parallel, and when the second refrigerant compressor 2 operates independently, most of the lubricating oil that returns is
The gas flows down the first gas suction pipe 4 and flows into the suction chamber 103 of the first refrigerant compressor 1.
Adjacent oil sump chamber 105 through oil equalizing check valve 108
The oil is returned to the oil reservoir chamber 205 of the second refrigerant compressor 2 via the oil equalizing pipe 10 and the check valve 11. This amount of oil returned is calculated from the suction pipe 3 of the refrigeration cycle.
Since the amount of lubricating oil returned is approximately equal to the amount of lubricating oil returned, the amount of oil in the oil sump chamber 105 of the first refrigerant compressor 1 and the oil sump chamber 205 of the second refrigerant compressor 2 is secured, and the amount of oil is not refilled as in the conventional device. Failures such as abnormal wear or seizure of sliding parts within the refrigerant compressor due to shortage will not occur.

On the other hand, in the conventional device, as described above, a part of the lubricating oil returning through the suction pipe 3 of the refrigeration cycle flows into the second gas suction pipe 5 and is transferred to the suction chamber 203 of the second refrigerant compressor 2. However, since the pressure in the suction chamber 203 of the second refrigerant compressor 2 is lower than the pressure in the adjacent oil sump chamber 205, the oil is not returned to the oil sump chamber 205, and the oil flows into the second refrigerant compressor 2. suction chamber 20
3, lubricating oil accumulates and is easily sucked into the liquid state together with the refrigerant gas, causing damage to the valve part due to oil compression.
Failures such as damage to the bore or valve plate may occur due to this, or an excessive amount of lubricating oil sent out together with the refrigerant gas at the gas discharge pipe of the refrigerant compressor may be separated using an oil separator or the like, and the evaporator ( Unless an excessive amount of lubricating oil is prevented from flowing into the tank (not shown), there is a problem in that the refrigerating capacity will be reduced.

However, in the embodiment of this invention, as described above, most of the lubricating oil returning through the suction pipe 3 of the refrigeration cycle is made to flow into the first gas suction pipe 4, and the lubricating oil returns to the second gas suction pipe 4.
gas suction pipe 5 and therefore the second refrigerant compressor 2
Since almost no lubricating oil is allowed to flow into the suction chamber 203 of the refrigerant compressor, no lubricating oil is accumulated in the suction chamber 203 and an excessive amount of oil does not rise. There is no need to install gas oil separation equipment such as an oil separator at the gas discharge part.

Note that in the above embodiment, there is a branch portion 1 where the second gas suction pipe 5 branches from a straight portion of the first gas suction pipe 4.
2, the opening end 501 of the second gas suction pipe 5 is made to project inward from the inner wall surface 401 of the first gas suction pipe 4. The pipe surface of the protrusion 502 has a uniform cylindrical shape. If the opening end 501 of the second gas suction pipe 5 has a downward slope due to a machining error or the like, the lubricating oil flowing along the bellmouth-shaped inner wall surface 1202 may leak from the protrusion 502 of the second gas suction pipe 5. The second gas suction pipe 5 runs along the surface from the open end 501.
There is a danger that it will turn inward.

In order to eliminate this problem, as shown in FIG. 5, the cylindrical surface of the protruding part 502 of the second gas suction pipe 5 in the branch part 12 is machined with a ring-shaped sawtooth groove along the circumference. , it is possible to prevent the lubricating oil from flowing along the surface of the protrusion 502 and into the second gas suction pipe 5 .

FIG. 6 shows a lubricating oil returning from the suction pipe 3 of the refrigeration cycle in order to hardly allow it to flow into the second gas suction pipe 5 and to make it pass only through the first gas suction pipe 4. This shows still another embodiment, in which the pipe end of the suction pipe 3 of the refrigeration cycle is located in the middle of the first gas suction pipe 4 that extends vertically or diagonally and communicates with the first refrigerant compressor 1. A branch section 6 is provided at right angles to the straight section to connect the branch section with a T-joint or the like, and the first gas suction pipe 4
An outward bell mouth insertion port 1201 is provided at a higher position than the branch part 6 at the upper part of the straight part of the second refrigerant compressor, similar to the branch part 12 shown in the embodiment of FIGS. 3 to 5 above. The opening end 501 of the second gas suction pipe 5 that communicates with the gas suction pipe 2 is configured to form a branch part 12 that protrudes from the inner wall surface 401 of the first gas suction pipe 4. With this configuration, a part of the lubricating oil tends to rise along the uniformly continuous arc-shaped branch inner wall surface 601 of the branch part 6, being attracted by the gas flow sucked into the refrigerant compressor 2. The steady gas flow drawn to the bellmouth-shaped inner wall surface 1202 and the slit 1203 is weak, and the force due to the gas flow etc. is sufficient to draw it from the slit 1203 to the open end 501 of the second gas suction pipe 5. does not work, so the lubricating oil eventually travels along the inner wall surface 401 of the first gas suction pipe 4 and enters the suction chamber 1 of the first refrigerant compressor 1 due to the action of gravity.
If the second refrigerant compressor 2 is in operation, the oil of the second refrigerant compressor 2 is supplied via the oil equalizing pipe 10 and the check valve 11. The oil is returned to the reservoir chamber 205, and an appropriate amount of oil is ensured in the oil reservoir chamber.

On the other hand, in the first gas suction pipe 4, the branch part 1
2 is provided above the branch part 6, the bellmouth-shaped inner wall surface 1 of the branch part 12 is
The amount of oil reaching 202 is small. Therefore, the function of preventing lubricating oil from flowing into the second gas suction pipe 5 is more reliable in the embodiment shown in FIG. 6 than in FIGS. 3 and 4.

[Effect of idea]

As explained above, this idea is based on the first and second
In a parallel compression type refrigeration system comprising a refrigerant compressor, a second gas suction pipe is branched from a first gas suction pipe that serves as a passage for gas to the first refrigerant compressor and extends in the vertical direction. The opening end of the second gas suction pipe at this branch part is configured to protrude inward from the bellmouth-shaped inner wall surface of the outward bellmouth insertion port of the first gas suction pipe. The second gas suction pipe in the structure allows
By communicating the first gas suction pipe and the second refrigerant compressor, the lubricating oil returning to the suction pipe of the refrigeration cycle is transferred to the second gas suction pipe and therefore to the second refrigerant compressor. Since the structure is such that almost no oil flows into the second refrigerant compressor 2, damage to the valve part due to excess oil in the second refrigerant compressor,
There is no damage to the bore, valve plate, etc. due to this. Further, since there is no excessive amount of oil coming up and therefore no excessive amount of lubricating oil flowing into the evaporator, it is possible to prevent a decrease in the refrigerating capacity. In addition, most of the lubricating oil is returned to the first refrigerant compressor through the first gas suction pipe, and furthermore, in the case of parallel operation and when the second refrigerant compressor operates independently, Since the oil is returned to the oil storage chamber of the second refrigerant compressor via the oil equalizing pipe and check valve, the oil is returned to the oil storage chamber of the second refrigerant compressor, so that the An appropriate amount of oil is ensured, and the lubricating function of the sliding parts within the refrigerant compressor is maintained.

[Brief explanation of the drawing]

Figure 1 is a piping diagram of a conventional parallel compression refrigeration system.
Figure 2 shows the suction pipe 3 of the refrigeration cycle in Figure 1.
is a detailed sectional view showing an enlarged branch part 6 that branches into a first gas suction pipe 4 and a second gas suction pipe 5,
Fig. 3 is a piping diagram of a parallel compression type refrigeration system showing one embodiment of this invention, and Fig. 4 shows the
FIG. 5 is an enlarged detailed sectional view showing a branch part 6 where the second gas suction pipe 5 branches from the vertical part of the gas suction pipe 4. FIG. 5 is an enlarged detailed cross-sectional view showing another embodiment of the branch part 6. It is a diagram. FIG. 6 is a detailed cross-sectional view showing still another embodiment of a branch part where the suction pipe 3 of the refrigeration cycle branches into a first gas suction pipe 4 and a second gas suction pipe 5. In the figure, 1 is a first refrigerant compressor, 2 is a second refrigerant compressor, 4 is a first gas suction pipe, 5 is a second gas suction pipe, 11 is a check valve, 12 is a branch part, 40
1 is the inner wall surface of the first gas suction pipe 4, 501 is the second
This is the open end of the gas suction pipe 5. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] A first and a second refrigerant compressor, the first refrigerant compressor and the second refrigerant compressor are connected to each other, and the oil flows only from the first refrigerant compressor to the second refrigerant compressor. an oil equalizing pipe having a check valve that allows for the same, a first gas suction pipe extending in the vertical direction and through which gas passes to the first refrigerant compressor, and branching from the first gas suction pipe and a branching portion thereof. The opening end in the first
The first gas suction pipe protrudes inward from the bellmouth-shaped inner wall surface of the outward bellmouth insertion port in the gas suction pipe, and communicates the first gas suction pipe with the second refrigerant compressor, thereby reducing the pressure loss of the first gas suction pipe. A parallel compression refrigeration system with a second gas suction pipe configured to have a larger pressure drop.