JPH04214989A - Coupled compression equipment - Google Patents

Abstract

PURPOSE:To prevent the oil level of a high pressure side compressor from dropping so as to keep the oil level of each compressor proper by sending most of oil which returns to a first suction pipe back to the high pressure side compressor, and shifting oil to a low pressure side compressor through an oil equalizing pipe. CONSTITUTION:A second suction pipe 4 is made to branch from the middle of a first suction pipe 3 and the branch end portion 41 of the pipe 4 is made to project into the pipe 3 and a difference is generated between the respective pressure losses of suction passages so that a first compressor 1 is located on high pressure side while a second compressor 2 is located on low pressure side. An uneven portion 6 comprising a thread groove and/or a porous body is provided on the inner wall of that portion of the first suction pipe 3 which is on the upper side of the branch portion, thereby increasing collectability of oil mist entrained in return oil and reducing the amount of oil mist flowing into the second suction pipe 4.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention comprises a plurality of compressors,
The present invention relates to a connected compression device suitable for relatively large-scale refrigeration systems such as building air conditioning systems.

0002

2. Description of the Related Art Conventionally, as this type of compression device, one disclosed in Japanese Patent Application Laid-Open No. 2-45665 is known.

As shown in FIG. 4, this compressor is equipped with first and second compressors A and B each having a compression element C housed in a casing D having an oil reservoir O. Then, a second suction pipe L connected to the second compressor B is branched in the middle of the first suction pipe H connected to the first compressor A, and the branch starting end E is connected to the inner wall of the first suction pipe H. is also located on the inner side to create a difference in pressure loss in the suction path, thereby forcing the first compressor A to be on the high pressure side and the second compressor B on the low pressure side. By injecting L into the first suction pipe H, the oil that once flows out to the external equipment side such as the condenser together with the discharge gas and returns mainly along the inner wall surface of the first suction pipe H is removed from the high pressure side. A large amount is returned to the first compressor A. In this way, oil is constantly moved from the first compressor A on the high pressure side, where more oil returns, to the second compressor B on the low pressure side through the oil equalizing pipe T, ensuring an appropriate oil level in both compressors A and B. I'm trying to make it possible.

0004

[Problem to be Solved by the Invention] With the above, in order to ensure an appropriate oil level for both compressors A and B, the amount of oil returned to the first compressor A, which is the high pressure side, must be adjusted to the low pressure side. The amount of oil returned to the second compressor B is sufficiently increased compared to the amount of oil returned to the second compressor B, and the amount of oil returned to the first compressor A is transferred from the first compressor A to the second compressor B via the oil equalizing pipe T. The amount shall be necessary and sufficient to replenish the amount of oil transferred. For this reason, the branch starting end E of the second suction pipe L is located inward from the inner wall of the first suction pipe H, and the inner wall surface of the first suction pipe H is mainly formed into an annular shape due to the wettability of the oil. This makes it difficult for the oil that comes back to flow into the second suction pipe L, and relatively increases the amount of oil that is returned to the first compressor A.

However, the oil returning through the first suction pipe H not only flows in an annular flow along the inner wall surface of the first suction pipe H, but also flows inside the first suction pipe H due to the flow velocity of the gas. Since it contains mist-like oil that is distributed throughout and flows, if the structure is such that the branch starting end E of the second suction pipe L is simply pushed into the first suction pipe H, the oil mist easily flows to the second suction pipe L side. This results in a relative decrease in the amount of oil returned to the first compressor A side. As a result, compared to the amount of oil that moves from the first compressor A to the second compressor B through the oil equalizing pipe T, the amount of oil that returns from the first suction pipe H to the first compressor A decreases, and the amount of oil that returns to the first compressor A decreases. A problem occurs in which the oil level of machine A drops abnormally. Here, it is thought that the oil level of the first compressor A will not fall below the opening position of the oil equalizing pipe T, but during operation, the oil is turned into mist inside the casing due to the stirring action of the rotating parts, etc. Therefore, the oil mist floating in this casing moves to the second compressor B through the oil equalizing pipe T, and eventually the oil level in the first compressor A drops below the opening position of the oil equalizing pipe T. However, the first compressor A cannot secure a sufficient oil level, which may lead to poor lubrication. In particular, when using a scroll type compression element,
Since it is necessary to ensure sufficient oil supply to the scroll spiral body, there is a large amount of oil mist floating inside the casing, and the amount of oil that flows out with the discharged gas and the amount of oil that returns is also large, so this problem is solved. noticeable.

The object of the present invention is to improve the structure upstream of the branch of the suction pipe so that a necessary and sufficient amount of oil can be returned to the compressor on the high pressure side, and a connection can be achieved that allows for proper oil level management. An object of the present invention is to provide a mold compression device.

[0007]

[Means for Solving the Problems] Therefore, in order to achieve the above object, the present invention includes a plurality of compressors 1 and 2 each having a compression element built into a casing having an oil reservoir. A second suction pipe 4 connected to another compressor 2 is branched in the middle of the first suction pipe 3 connected to the first suction pipe 3, and the branch starting end 41 of the second suction pipe 4 is connected to the inner wall of the first suction pipe 3. In a connected compression device in which the oil equalizing pipe 7 is connected between the compressors 1 and 2, the first suction pipe 3 is located on the upstream side of the branch part of the second suction pipe 4. A concavo-convex portion 6 was provided on the inner wall.

The uneven portion 6 includes a thread groove 61 and a porous body 6.
Form with 2.

Furthermore, in the case where a scroll type compression element is used, the countermeasure using the uneven portion 6 is particularly effective.

0010

[Function] By providing the uneven portion 6 composed of the thread groove 61, the porous body 62, etc., it is possible to improve the oil collection property on the inner wall surface of the first suction pipe 3, and the oil flowing in a distributed manner inside the pipe can be improved. The mist can be positively attached to the inner wall surface of the first suction pipe 3. As a result, the annular flow ratio of oil in the return oil can be increased, the amount of oil mist can be reduced, and the amount of oil mist flowing into the second suction pipe 4 side can be reduced, and the first suction pipe 3 can be A sufficient amount of oil can be returned to the connected high pressure side compressor 1. Further, oil is transferred from the high-pressure side compressor 1 to which a sufficient amount of oil is returned to the low-pressure side compressor 2 to which the second suction pipe 4 is connected through the oil equalizing pipe 7. In this way, an abnormal drop in the oil level in the high pressure side compressor 1 can be prevented, and the oil level in each compressor 1, 2 can be maintained at an appropriate level.

When a scroll type compression element is used, there is a large return oil flow and a large amount of oil mist is contained in this return oil, but since the uneven portion 6 reduces the amount of oil mist, each compressor The oil level at points 1 and 2 can be maintained at an appropriate level.

0012

[Embodiment] The connected compressor shown in Fig. 1 is a twin type equipped with a first and a second compressor 1, 2, and each compressor 1, 2 has an oil reservoir 10, 20 at the bottom, respectively. A scroll type compression element 12, 22 and a motor 14, 24 having a drive shaft 13, 23 for driving each compression element 12, 22 are housed in a closed type casing 11, 21.

As shown in FIG. 2, a second suction pipe 4 that connects to the second compressor 2 is branched in the middle of the first suction pipe 3 that connects to the first compressor 1. Starting end 41
is located more inward than the inner wall of the first suction pipe 3. In this way, the pressure loss of the second suction pipe 4 with respect to the first suction pipe 3 is increased, forcing the inside of the casing 11 of the first compressor 1 to the high pressure side and the casing 21 of the second compressor 2 to the low pressure side. I am trying to set it accordingly. In addition, by locating the branch starting end 41 of the second suction pipe 4 inwardly from the inner wall of the first suction pipe 3, the oil returning annularly along the inner wall of the first suction pipe 3 can be prevented. It is made difficult for the oil to flow toward the second suction pipe 4 side, so that the amount of oil returned to the first compressor 1 is relatively large.

Further, between the first compressor 1 on the high pressure side and the second compressor 2 on the low pressure side, pipes 71 and 72 are provided which open downward relative to the specified oil level of each oil reservoir 10 and 20. The oil equalizing pipe 7 is connected with a throttling means 8 using a loop-shaped thin pipe 81 in the middle.

Furthermore, discharge chambers 15 and 25 are provided in the upper part of each casing 11 and 21 to release the high pressure fluid compressed by each compression element 12 and 22, and a first and a first discharge chamber integrated into the discharge pipe 9 are provided in each chamber. Two discharge branch pipes 91 and 92 are connected.

With the above structure, the uneven portion 6 constituted by the threaded groove 61 is provided on the inner wall of the first suction pipe 3 located upstream of the branching portion of the second suction pipe 4.

[0017] This makes it possible to improve oil collection in the portion of the first suction pipe 3 where the threaded groove 61 is formed, and the oil mist distributed and flowing inside the first suction pipe 3 is It becomes easy to adhere to the inner wall surface of No.3. In this way, the proportion of the annular flow a of oil in the return oil is increased, the absolute amount of oil mist is reduced, and the amount of oil mist flowing into the second suction pipe 4 side can be reduced accordingly, and the first compression This allows a sufficient amount of oil to be returned to machine 1. Also, a sufficient amount of oil is returned from the first compressor 1 to the second compressor 2.
The oil is transferred to the second compressor 2 through the oil equalizing pipe 7, and the oil level in the second compressor 2 can also be maintained at an appropriate level. Therefore, an abnormal drop in the oil level in the first compressor 1 can be prevented, and the oil levels in both the first compressor 1 and the second compressor 2 can be maintained at appropriate levels.

[0018] In addition to the concave and convex portion 6 being constituted by a threaded groove 61,
As shown in FIG. 3, the uneven portion 6 may be formed by interposing a porous body 62 made of a porous cylinder, a porous sheet, etc. on the inner wall of the first suction pipe 3. In this case, it is possible to improve the oil collection performance at the formation site of the porous body 62, reduce the amount of oil mist contained in the returned oil, and reduce the amount of oil flowing into the second suction pipe 4 side. can be reduced. Furthermore, it is also possible to form the uneven portion 6 by, for example, finishing the inner wall surface of the first suction pipe 3 with a rough surface.

In the above embodiments, a twin type compressor is shown, but it goes without saying that the present invention can also be applied to a compressor in which three or more compressors are connected.

[0020]

As described above, according to the present invention, since the uneven portion 6 composed of the thread groove 61, the porous body 62, etc. is provided upstream of the branching part of the second suction pipe 4, the amount of oil occupied in the return oil is reduced. The compressor on the high pressure side to which the first suction pipe 3 is connected can improve the annular flow ratio and reduce the amount of oil mist, and can reduce the amount of oil mist flowing from the first suction pipe 3 to the second suction pipe 4. 1, a sufficient amount of oil can be returned to the compressor 1 on the high pressure side, preventing an abnormal drop in the oil level in the compressor 1 on the high pressure side, and maintaining the oil level in each compressor 1, 2 at an appropriate level.

When a scroll type compression element is used, there is a large return oil flow and a large amount of oil mist is contained in this return oil. The oil level in machines 1 and 2 can be maintained at an appropriate level.

[Brief explanation of the drawing]

FIG. 1 is a piping diagram showing the overall structure of a connected compression device according to the present invention.

FIG. 2 is a sectional view of essential parts of the first embodiment.

FIG. 3 is a sectional view of a main part of the second embodiment.

FIG. 4 is a piping diagram showing a conventional connected compression device.

[Explanation of symbols]

1 First compressor 2 Second compressor 3 First suction pipe 4 Second suction pipe 6 Uneven part 7 Oil equalizing pipe 41 Branch start end 61 Thread groove 62 Porous body

Claims (4)

[Claims] Claim 1: A plurality of compressors 1 and 2 each having a compression element built into a casing having an oil reservoir, one compressor 1
A second suction pipe 4 connected to another compressor 2 is branched in the middle of the first suction pipe 3 connected to the first suction pipe 3, and the branch starting end 41 of the second suction pipe 4 is connected to the inner wall of the first suction pipe 3. In a connected compression device in which the oil equalizing pipe 7 is connected between the compressors 1 and 2, the first suction pipe 3 is located on the upstream side of the branch part of the second suction pipe 4. A connected compression device characterized in that an uneven portion 6 is provided on the inner wall of the device. 2. The connected compression device according to claim 1, wherein the uneven portion 6 is a thread groove 61. 3. The connected compression device according to claim 1, wherein the uneven portion 6 is formed of a porous material 62. 4. The coupled compression device according to claim 1, wherein the compression element is of a scroll type.