JP2002021758A - Oil-cooled screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an agitating loss of a lubricating oil. SOLUTION: An end part of a screw rotor 11 is rotatably supported by a suction side bearing 14. A first recovering hole 31 is formed in a partition wall 21 between the screw rotor 11 and the suction side bearing 14, and a second recovering hole 32 is formed by bypassing the first recovering hole 31. A recessed part 33 is formed on the partition wall 21, and the first recovering hole 31 and the second recovering hole 32 are opened in the recessed part 33. With such constitution, in the lubricating oil fed from an oiling hole 29, a part lubricates the suction side bearing 14, and flows to the recessed part 33 via the first recovering hole 31, and the residue directly flows to the recessed part 33 via the second recovering hole 32, and is recovered to a compressed air suction passage 34 from the recessed part 33. Thus, an agitating loss in the suction side bearing 14 and an agitating loss on the opening end of the first recovering hole 31 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an oil-cooled screw compressor, and more particularly to a screw compressor having an improved lubricating oil system for lubricating bearings and the like.

[0002]

2. Description of the Related Art Generally, an oil-cooled screw compressor is provided with a driving screw rotor connected to an external rotary driving source, and a driven screw rotor meshing with the driving screw rotor. The drive-side screw rotor and the driven-side screw rotor are rotatably supported at the suction-side end by a suction-side bearing and the discharge-side end by a discharge-side bearing. When driven to rotate, the driven screw rotor also rotates, thereby sucking, compressing and discharging a fluid such as air. The suction-side end of the drive-side screw rotor has a shaft portion, and this shaft portion is connected to an external rotary drive source. This shaft portion is provided with a mechanical seal. The drive-side screw rotor, the driven-side screw rotor, the suction-side bearing, the discharge-side bearing, and the mechanical seal are housed in a casing, and the casing houses the space in which the suction-side bearing is housed and the drive-side screw rotor. A partition is provided between the space and the space.

In such an oil-cooled screw compressor, a mechanical seal, a suction-side bearing and a discharge-side bearing are lubricated while being cooled by lubricating oil supplied from outside the compressor. For example, lubricating oil is supplied to the suction side bearing from the opposite side of the screw rotor, and when the lubricating oil passes, the suction side bearing is cooled and lubricated. After lubricating the suction-side bearing, the lubricating oil flows toward the drive-side screw rotor via a recovery hole formed in the partition wall and is recovered.
This recovery hole is usually formed at a position corresponding to the middle between the outer ring and the inner ring of the suction side bearing in order to quickly recover the lubricating oil after lubrication of the suction side bearing.

[0004]

The required amount of lubricating oil in the suction-side bearing is smaller than that required in the mechanical seal. However, in the above-mentioned conventional technology, since all of the lubricating oil after the mechanical seal lubrication passes through the suction-side bearing, the amount of the lubricating oil to the suction-side bearing becomes excessive, and the lubricating oil in the suction-side bearing is Stirring loss occurs.

[0005] The suction method of the screw compressor main body includes an axial suction method in which fluid is sucked in the axial direction of the screw rotor and a radial suction method in which the fluid is sucked in the radial direction of the screw rotor. When the lubricating oil is recovered from the recovery hole formed in the above, a stirring loss also occurs. That is, in the case of the radial suction method, the gap between the wall surface of the partition wall in which the recovery hole is formed and the end surface of the screw rotor is very small (200 mm in diameter).
If the recovery hole is formed at a position corresponding to the middle between the outer ring and the inner ring of the suction-side bearing as described above, the recovery of the lubricating oil to the screw rotor side is performed by the screw rotor. When the teeth coincide with the collecting holes, the rotation is restricted, and the lubricating oil is intermittently collected with the rotation of the screw rotor, which causes an increase in lubricating oil stirring loss.

[0006] It is an object of the present invention to reduce lubricating oil stirring loss.

[0007]

In order to solve the above-mentioned problems, the present invention provides a pair of screw rotors for sucking, compressing and discharging a fluid, and a suction side for rotatably supporting a suction-side end of the screw rotor. A bearing, a discharge-side bearing rotatably supporting a discharge-side end of the screw rotor, and a screw rotor, a suction-side bearing, and a discharge-side bearing are housed therein.
A casing in which a flow path for supplying lubricating oil to the suction side bearing from the opposite side of the screw rotor is formed, and a partition formed between a space in which the suction side bearing is stored and a space in which the screw rotor is stored. A first recovery hole for allowing the lubricating oil after lubricating the suction-side bearing to flow to the screw rotor side and collecting the lubricating oil, and a part of the lubricating oil formed in the partition wall and supplied to the suction-side bearing is directly guided to the screw rotor side. And a second collection hole for collection.

According to the above construction, a part of the lubricating oil is recovered through the second recovery hole, so that the amount of the lubricating oil passing through the suction-side bearing is suppressed to a minimum necessary for lubrication. Thereby, the stirring loss of the lubricating oil in the suction side bearing can be reduced.

[0009] The second recovery hole can be formed at a position outside the outer ring of the suction-side bearing. Further, the second recovery hole can be opened in a portion other than the compression chamber of the screw rotor.

Further, the present invention is characterized in that when the screw rotor is of a type in which the fluid is sucked from the radial direction, a concave portion is formed in the side wall surface of the screw rotor of the partition wall, and a second recovery hole is opened in the concave portion. And With this configuration, since the lubricating oil from the collecting hole is collected in the concave portion, even if the gap between the partition wall surface and the end surface of the screw rotor is narrow, lubricating oil stirring loss does not occur.

Incidentally, the first recovery hole may be opened in the compression chamber of the screw rotor.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) First, an example in which the present invention is applied to a radial suction type screw compressor will be described. 2 and 3 show a radial suction type oil-cooled screw compressor. FIG. 2 is a horizontal sectional view, and FIG. 3 is a vertical sectional view. This oil-cooled screw compressor 10 is driven side (male type).
It has a screw rotor 11 and a driven side (female type) screw rotor 12, and the two screw rotors 11, 12 mesh with each other. As for the drive side screw rotor 11 and the driven side screw rotor 12, the left side of the drawing is the suction side,
The right side is the discharge side. The drive-side screw rotor 11 and the driven-side screw rotor 12 are
The main casing 13 has an air suction port 1 corresponding to the suction sides of the screw rotors 11 and 12.
3A is provided.

The suction sides of the two screw rotors 11 and 12 are connected to a suction-side bearing 1 fixed to a main casing 13.
4 and 15 rotatably supported. The discharge sides of the screw rotors 11 and 12 are rotatably supported by discharge-side bearings 17 and 18 fixed to a discharge-side casing 16. The discharge casing 16 is connected to the main casing 13 by connecting pins 20.

A partition 21 which is a part of the main casing 13 is formed between the space where the suction-side bearings 14 and 15 are provided and the space where the two screw rotors 11 and 12 are provided. The space in which the suction side bearings 14 and 15 are provided is covered with a suction side cover 22, and this space is a suction side chamber 23. Drive side screw rotor 11
Has a shaft portion 24 connected to a rotary drive source such as a motor (not shown). The shaft portion 24 is provided with a mechanical seal 25. The mechanical seal 25 is disposed in the suction side chamber 23 covered with the suction side cover 22. Further, the space in the discharge side casing 16 in which the discharge side bearings 17 and 18 are provided is the discharge side cover 2.
6 and this space communicates with the discharge port 27.

Oil supply holes 28 and 29 are formed in the suction side cover 22, and these oil supply holes 28 and 29 are formed in the suction side cover 2.
2 communicates with the suction side chamber 23. In addition, as shown in FIG.
First recovery hole 3 that communicates a space in which suction-side bearing 14 is provided with a space in which drive-side screw rotor 11 is provided.
1 is formed. Further, a second collection hole 32 is formed bypassing the first collection hole 31. Further, a concave portion 33 is formed on the suction-side end surface of the partition wall 21 (the surface on the side where the drive-side screw rotor 11 is provided), and a first recovery hole 31 and a second recovery hole 32 are opened in the concave portion 33, respectively. are doing. The recess 33 is provided in the compressed air suction passage 3.
It communicates with 4. In addition, 35, 36 are the second collection holes 3
2 is a plug that closes a hole formed when opening 2.

FIG. 4 is a view of the suction-side end face of the partition 21 as viewed from the screw rotor side. 4, reference numeral 41 denotes the outer diameter of the driving screw rotor 11, 42 denotes the root diameter of the driving screw rotor 11, 43 denotes the outer diameter of the suction bearing 14, and 44 denotes the shoulder contact inner diameter of the outer ring 14A of the suction bearing 14. It is. 45 is the outer diameter of the driven screw rotor 12;
Is the root diameter of the drive-side screw rotor 12, 47 is the outer diameter of the suction-side bearing 15, and 48 is the shoulder contact inner diameter of the outer ring of the suction-side bearing 14. Also, 49 is a boundary line with the compression chamber in the center of the figure.

A first recovery hole 31 and a second recovery hole 32 are provided on the driving screw rotor 11, and a third recovery hole 50 is provided on the driven screw rotor 12 side. The third collecting hole 50 also opens in a concave portion 51 formed in the partition 21. These recovery holes 31, 32,
The opening 50 is located outside the boundary 49 as shown in FIG.

The first recovery hole 31 is formed at a position not less than the root diameter 42 of the driving screw rotor and not more than the shoulder contact inner diameter 44 of the suction-side bearing outer ring 14A. The second recovery hole 32 is formed at a position not less than the outer diameter 43 of the suction-side bearing and not more than the outer diameter 41 of the drive-side screw rotor. Further, since the root diameter 46 of the driven screw rotor is less than or equal to the shoulder contact inner diameter 48 of the outer bearing ring on the suction side, the third collection hole 50 has the root diameter 46 of the driven screw rotor.
It is formed in the following position. In this position, although it is constantly closed by the suction side end face of the driven side screw rotor, since the concave portion 51 is provided,
There is no problem with lubrication oil recovery. The concave portion 51 is formed up to a position which is equal to or larger than the root diameter 46 of the driven screw rotor.

In the above configuration, the lubricating oil is supplied to the oil supply holes 28,
29, the oil is supplied to the suction side chamber 23, and the suction side bearing 1
On the side 4, the mechanical seal 25 is lubricated, and a part of the mechanical seal 25 flows to the suction side bearing 14 to lubricate the suction side bearing 14. The lubricating oil that lubricated the suction side bearing 14
It flows to the recess 33 through the first recovery hole 31. The remaining lubricating oil that has not flowed to the suction side bearing 14 is supplied to the second recovery path 32.
Through the recess 33. Then, the lubricating oil flowing to the concave portion 33 flows to the compressed air suction passage 34 and is collected.

As described above, in the present embodiment, since the second recovery hole 32 is provided, the amount of the lubricating oil flowing to the suction-side bearing 14 is limited, and the loss of the lubricating oil in the suction-side bearing 14 is reduced. Can be reduced. Further, since the concave portion 33 is formed in the partition wall 21 and the first recovery hole 31 and the second recovery hole 32 are opened in the concave portion 33, the driving side screw rotor 11 is formed.
Is rotated, the collection hole 31 and the second collection hole 32
Lubricating oil is smoothly recovered, and the stirring loss here can be reduced.

On the other hand, on the side of the suction side bearing 15, the lubricating oil mainly supplied from the oil supply hole 28 lubricates the suction side bearing 15, and thereafter, the lubricating oil is supplied to the recess 51 through the third recovery hole 50. Flows to Since the concave portion 51 is formed to a position equal to or larger than the root diameter 46 of the driven screw rotor as described above, even if the driven screw rotor 12 is rotating, the lubricating oil flowing into the concave portion 51 is not driven by the driven screw. It flows to the rotor and is easily collected. Note that, in the present embodiment, a collection hole that bypasses the third collection hole 50 is not provided. This is because the first collection hole 31 and the second collection hole 32
Is formed at a position lower than the third recovery hole 50, so that excess lubricating oil at the suction-side bearing 15 is removed from the suction-side bearing 1.
This is because it naturally flows to the direction 4 and is collected through the first collection hole 31 or the second collection hole 32.

In the present embodiment, the first collection hole 3
The hole diameter of the first and third recovery holes 50 is determined by the suction side bearing 14,
In order to reduce the agitation loss at 15, the hole diameter is set so that only the minimum required amount of lubricating oil flows through the suction-side bearings 14, 15.

(Embodiment 2) Next, an example in which the present invention is applied to an axial suction type screw compressor will be described. 5 and 6 show an axial suction type oil-cooled screw compressor, FIG. 5 is a horizontal sectional view, and FIG.
Is a vertical sectional view. The same parts as those of the radial suction type screw compressor are denoted by the same reference numerals, and detailed description thereof will be omitted.

The axial suction type oil-cooled screw compressor 60 has a screw rotor that suctions air from its axial direction. As shown in the drawing, a main casing 13 has suction-side end faces of the screw rotors 11 and 12 (see FIG. 1). A suction port 61 is provided corresponding to (left side in the figure). And
In the present embodiment, a first recovery path 31 and a second recovery path 32 as shown in FIG.
In the axial suction system, since the suction port 61 is provided, the suction-side end surfaces of the screw rotors 11 and 12 are separated from the partition 21, and a recess is formed on the partition 21 as in the radial suction system. No need.

In the present embodiment, as in the first embodiment, the second recovery hole 32 is provided, so that the amount of lubricating oil flowing to the suction side bearing 14 is limited. Can reduce the loss of agitation of the lubricating oil.

(Embodiment 3) FIG. 7 shows Embodiment 3 of the present invention. In the present embodiment, the first recovery hole 31 and the third recovery hole 50 open inside the boundary 49, that is, open to the compression chamber. Further, a rhombus-shaped concave portion 70 is formed on the wall surface of the partition wall, and the first recovery hole 31 and the third recovery hole 50 are opened in the concave portion 70.

The first recovery hole 31 and the third recovery hole 50
Since the temperature of the lubricating oil flowing through is high, if the lubricating oil is recovered in the compressed air suction passage 34, the suction air may be heated, but if the lubricating oil is configured as in the present embodiment,
Heating of the suction air can be suppressed.

Further, the same operation and effect can be obtained by the method shown in FIG. In FIG. 8, the first recovery hole 31 and the third recovery hole 50 are open to the compression chamber, and the second recovery hole 32 is also open to the compression chamber. A triangular concave portion 71 is formed on the wall surface of the partition, and the first collecting hole 3 is formed.
The first, second and third collection holes 32 and 50 are all open to the recess 70.

(Embodiment 4) FIG. 9 shows Embodiment 4 of the present invention. This embodiment is an example applied to a radial suction type screw compressor. In this screw compressor, an oil supply hole 72 is formed in the wall surface 21, and the lubricating oil from the oil supply hole 72 flows into the suction side bearing 14 from the screw rotor 11 side to lubricate the suction side bearing 14.
The lubricating oil after lubrication of the suction side bearing 14 further lubricates the mechanical seal 25 and flows through the collecting hole 73 to be collected.

In the screw compressor having such a configuration, the gap between the partition 21 and the suction-side end face of the screw rotor 11 is very narrow, and a loss of stirring of the lubricating oil occurs.

In the present embodiment, a recess 74 is formed in the suction-side end face of the partition wall 21, and the recovery hole 73 is opened in the recess 74. Thereby, the stirring loss of the lubricating oil can be reduced.

[0032]

As described above, according to the present invention,
Since the stirring loss of the lubricating oil can be reduced, the performance of the compressor can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a screw compressor according to the present invention.

FIG. 2 is a horizontal sectional view of a radial suction type screw compressor.

FIG. 3 is a vertical sectional view of a radial suction type screw compressor.

FIG. 4 is a view of the partition seen from the screw rotor side.

FIG. 5 is a horizontal sectional view of an axial suction type screw compressor.

FIG. 6 is a vertical sectional view of an axial suction type screw compressor.

FIG. 7 is a view showing a modification of the position of the collection hole.

FIG. 8 is a view showing another modification of the position of the collecting hole.

FIG. 9 is a sectional view of a main part of a radial suction type screw compressor having a different oil supply type.

DESCRIPTION OF SYMBOLS 10 Radial suction type screw compressor 11 Drive screw rotor 12 Driven screw rotor 13 Main casing 14, 15 Suction side bearing 16 Discharge side casing 17, 18 Discharge side bearing 21 Partition wall 22 Suction side cover 23 Suction Side chamber 24 Shaft part 25 Mechanical seal 26 Discharge side cover 28, 29 Oil supply hole 31 First recovery hole 32 Second recovery hole 33, 51, 70, 71 Recess 34 Compressed air suction passage 41 Outer diameter of drive side screw rotor 42 root diameter of drive side screw rotor 43 outer diameter of suction side bearing 14 44 shoulder contact inner diameter of suction side bearing 14 45 outer diameter of driven side screw rotor 46 root diameter of driven side screw rotor 47 outside of suction side bearing 15 Diameter 48 Shoulder contact inner diameter of suction side bearing 15 49 Boundary line with compression chamber 50 Third recovery hole 60 Axial suction type screw compressor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Riichi Uchida 502, Kandachicho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (72) Hideharu Tanaka 390 Muramatsu, Shimizu-shi, Shizuoka Hitachi, Ltd. F-term in equipment group (reference) 3H029 AA03 AA17 AA21 AB01 BB08 CC17 CC22 CC55

Claims (5)

[Claims] 1. A pair of screw rotors for sucking, compressing and discharging a fluid, a suction-side bearing rotatably supporting a suction-side end of the screw rotor, and a discharge-side end of the screw rotor rotatably. A discharge-side bearing to be supported, the screw rotor, the suction-side bearing and the discharge-side bearing are housed, and a casing in which a flow path for supplying lubricating oil to the suction-side bearing from the opposite side of the screw rotor is formed, A first is formed in a partition wall between a space in which the suction-side bearing is housed and a space in which the screw rotor is housed, and collects the lubricating oil after lubricating the suction-side bearing by flowing to the screw rotor side. A collecting hole, and a second collecting hole for guiding a part of the lubricating oil formed in the partition wall and supplied to the suction side bearing directly to the screw rotor side to collect the lubricating oil. An oil-cooled screw compressor characterized by the following. 2. The oil-cooled screw compressor according to claim 1, wherein the second recovery hole is formed at a position outside an outer ring of the suction-side bearing. Machine. 3. The oil-cooled screw compressor according to claim 1, wherein the second recovery hole is opened in a portion other than the compression chamber of the screw rotor. Screw compressor. 4. The oil-cooled screw compressor according to claim 1, wherein when the screw rotor is of a type in which fluid is sucked from a radial direction, a recess is formed in a side wall surface of the screw rotor of the partition wall. An oil-cooled screw compressor, wherein the second recovery hole is opened in the recess. 5. The oil-cooled screw compressor according to claim 1, wherein the first recovery hole is opened in a compression chamber of the screw rotor.