JPH10288175A - Oil-cooled screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain shortening of longevity of a bearing due to loss of motive force by residence and stirring of oil flowed out from a bearing part of the discharge side and increase of normal thrust force to the minimum limit. SOLUTION: This oil-cooled screw compressor is furnished with a through hole 4 and an oil return channel 24 to introduce oil flowed out to the through hole 4 through spaces 17, 18 from bearings 19, 20 to a tooth groove part of screw rotors 11, 12 not communicated to a discharge port on an outer ring holding sleeve 1 to fix outer rings of the bearings 19, 20 facing the free end side spaces 17, 18 of discharge side rotor shafts 13, 14 of the male and female screw rotors 11, 12 to be engaged with each other. Additionally, flange parts are provided on both end parts of the outer ring holding sleeve 1, this outer diameter is made large in comparison with an intermediate part between the both end parts, that is, an outer diameter of a cylindrical body, and a ring space 5 to communicate the through hole 4 and the oil return channel 24 to each other is formed outside of this cylindrical body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-cooled screw compressor in which oil injected into a bearing portion is returned to a rotor chamber.

[0002]

2. Description of the Related Art Conventionally, an oil-cooled screw compressor in which male and female screw rotors 11, 12 are arranged laterally as shown in FIG. 5, and male and female screw rotors 11, 1 as shown in FIG.
2. Description of the Related Art An oil-cooled screw compressor in which two are arranged in a vertical direction is known. In these compressors, the screw rotors 11, 12
The rotor shafts 13 and 14 on the discharge side are rotatably supported by bearings 15 and 16, and bearings 19 facing the spaces 17 and 18 in a substantially suction pressure state on the free end sides of the rotor shafts 13 and 14. , 20 are fixed by a cylindrical outer ring holding sleeve 21. In addition, each screw rotor 1
Oil is supplied from an oil supply passage 22 to the shaft sealing portions between the bearings 1 and 12 and the bearing portions 15 and 16. This oil is supplied to the discharge sides of the screw rotors 11 and 12 and the spaces 17 and 18.
The screw rotor 11, 1 at the shaft seal
2 serves to shut off the space between the rotor chamber accommodating the bearings 2 and the above-mentioned spaces 17 and 18, and from there, the bearings 15, 16
Into the space 1 after lubrication of the bearing portions 15 and 16
Outflow to 7,18.

[0005] In the case of the compressor shown in FIG. 5, a through hole 23 is formed at the lowermost part of the outer ring holding sleeve 21.
This through-hole 23 is an oil return flow path 24 that communicates with the tooth groove portions of the screw rotors 11 and 12 that do not communicate with the discharge port, usually from the tooth groove portion where the gas suction has started to be slightly closer to the discharge side.
It is open to. Then, from the shaft sealing portion to the bearing portion 15,
The oil that has flowed out into the low-pressure spaces 17 and 18 via the nozzle 16 and dropped by its own weight is sucked and collected by the oil return passage 24 from the through-hole 23 into the tooth grooves of the screw rotors 11 and 12, and is used repeatedly. It has become.

On the other hand, in the case of the compressor shown in FIG.
A through hole 25 is formed from the lowermost part of the upper outer ring holding sleeve 21 to the lower outer ring holding sleeve 21, and a through hole 26 is formed in the lowermost part of the lower outer ring holding sleeve 21.
Is formed. The through hole 26 is open to the oil groove 27 of the screw rotor 11 which is not communicated with the discharge port, and the oil return flow path 27 which is opened to the tooth groove part slightly closer to the discharge side than the tooth groove part which normally started to suck the gas. Then, similarly to the above, the space 1 having a low pressure is passed through the shaft sealing portion and the bearing portions 15 and 16.
The oil that has flowed out into the holes 7 and 18 and dropped under its own weight
6 or the oil return flow path 27 through the through hole 26
From the tooth space of the screw rotor 11 to be collected, and used repeatedly.

[0005]

In the above-described compressor, since the inner rings of the rotor shafts 13 and 14 and the bearings 15 and 16 are rotating at a high speed (typically 3000 to 6000 rpm), the compressor 15 The spilled oil turns by centrifugal force,
Oil does not easily flow out from the lower through holes 23 or 25 and 26, and the oil stays in the spaces 17 and 18. Then, the accumulated oil is transferred to the rotor shafts 13 and 14 and the bearing portions 15 and 1.
Since the stirring is performed by the inner ring of No. 6, there is a problem that power loss occurs.

In particular, when these compressors are used in refrigerators, the refrigerant dissolves in oil, and when the oil flows into the spaces 17, 18, it is degassed, generating a large amount of refrigerant gas. Then, in a state where the oil is not well discharged from the through holes 23 or 25 and 26, the generated refrigerant gas is also poorly discharged, and the pressure in the spaces 17 and 18 increases. Due to this increase in pressure, the positive thrust force pushing the end faces of the rotor shafts 13 and 14 increases,
There is also a problem that the bearing life is shortened. The present invention has been made with the object of eliminating such a conventional problem,
It aims to provide an oil-cooled screw compressor that can minimize the loss of oil flowing out of the bearing on the discharge side, power loss due to agitation, and shortening of bearing life due to increase in positive thrust force. is there.

[0007]

In order to solve the above-mentioned problems, the present invention provides an outer ring holding sleeve for fixing an outer ring of a bearing facing a free end side space of a discharge side rotor shaft of a male and female screw rotor meshing with each other. Oil-cooled screw compressor having a through hole, and an oil return flow path that guides oil flowing out of the bearing to the through hole through the space to the through hole to a tooth groove portion of the screw rotor that does not communicate with a discharge port. In the above, the outer diameter of both ends of the outer ring holding sleeve is made larger than the outer diameter of an intermediate portion between the both ends, and the through holes communicate with each other outside the intermediate portion, or An annular space communicating with the oil return flow path was formed.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 to 3 show an oil-cooled screw compressor according to a first embodiment of the present invention, and portions substantially common to the above-described oil-cooled screw compressor are denoted by the same reference numerals and described. Is omitted. This compressor is
As with the compressor shown in FIG. 5, the male and female screw rotors 11,
12 are arranged in the horizontal direction. And
The outer rings of the bearings 19, 20 facing the spaces 17, 18 on the free end sides of the rotor shafts 13, 14 are fixed by the outer ring restraining sleeve 1.

As shown in FIGS. 2 and 3, the outer ring restraining sleeve 1 has flanges 3 extending outward at both ends of a cylindrical body 2, and the outer diameter of the both ends is set at an intermediate value between the two ends. Outer diameter of the part,
In the case of the example shown here, it is formed so as to be larger than the outer diameter of the cylindrical body 2. Further, a plurality of, for example, six through holes 4 are formed in the cylindrical body 2 at appropriate intervals. Then, as shown in FIG.
With the outer rings of the bearings 19 and 20 being fixed, the annular space 5 is formed in an intermediate portion between the both ends, that is, outside the cylindrical body 2, and the annular space 5 penetrates. The hole 4 communicates with the oil return flow path 24.

[0010] As a result, the space 17,
The oil that has flowed out while rotating in the circumferential direction at 18 flows from the through hole 4 to the annular space 5 due to the centrifugal force, and the rotor shaft 1
Without being stirred by the inner races of the bearings 19 and 20, the oil is smoothly sucked from the annular space 5 through the oil return flow passage 24 into the tooth groove portions of the screw rotors 11 and 12 which do not communicate with the discharge ports. Collected and recycled. Therefore, in the case of this compressor, power loss due to agitation of oil in the spaces 17 and 18 and shortening of bearing life due to an increase in positive thrust force when used in a refrigerator as described above can be minimized.

FIG. 4 shows an oil-cooled screw compressor according to a second embodiment of the present invention, similar to the compressor shown in FIG.
This is a type in which male and female screw rotors 11 and 12 are arranged in a vertical direction. Then, the compressor shown in FIG.
6 is different from the compressor shown in FIG. 6 in that the outer ring holding sleeve 1 is used in place of the outer ring holding sleeve 21. In place of the through hole 25, a through hole for communicating the respective annular spaces 5 of the upper and lower outer ring holding sleeves 1 with each other. Except for the point that 6 is formed in the wall of the housing space of the bearing portions 15 and 16, the other portions are substantially the same. And the oil which flowed out of the bearings 19 and 20 to the spaces 17 and 18 by such a structure is caused to flow into the annular space 5,
From here, it is led into the oil return flow path 27, and the reduction of the bearing life due to the increase in the power loss and the positive thrust force is minimized as in the case of the first embodiment described above.

In each of the above-described embodiments, the outer ring suppressing sleeve 1 has a shape in which a groove having a rectangular cross section is formed on the outer peripheral portion of the cylindrical body 2, but the present invention is not limited to this. The outer ring holding sleeve 1 has a cross section V
The shape may be a shape having a U-shaped or U-shaped cross section. The number of the through holes 4 of the outer ring holding sleeve 1 is not limited.

[0013]

As is apparent from the above description, according to the present invention, the outer ring restraining sleeve for fixing the outer ring of the bearing facing the free end side space of the discharge side rotor shaft of the male and female screw rotors meshing with each other is provided. An oil-cooled screw compressor including a through hole and an oil return flow path that guides oil flowing out of the bearing through the space to the through hole to the tooth groove portion of the screw rotor that does not communicate with a discharge port. The outer diameter of both ends of the outer ring holding sleeve is made larger than the outer diameter of an intermediate portion between both ends, and the through holes communicate with each other outside the intermediate portion, or An annular space is formed to communicate with the oil return flow path. For this reason, power loss due to agitation of the oil flowing into the space facing the free end side space of the discharge-side rotor shaft of the screw rotor, and shortening of the bearing life due to an increase in the positive thrust force when the compressor is used for a refrigerator. Are minimized.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an oil-cooled screw compressor according to a first embodiment of the present invention, which is cut in a horizontal direction.

FIG. 2 is a front view of an outer ring holding sleeve in the compressor shown in FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a partial sectional view of an oil-cooled screw compressor according to a second embodiment of the present invention, taken in a vertical direction.

FIG. 5 is a partial sectional view of a conventional oil-cooled screw compressor cut in a horizontal direction.

FIG. 6 is a vertical sectional view of another conventional oil-cooled screw compressor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Outer ring holding sleeve 4 Through hole 5 Annular space 6 Through hole 11, 12 Screw rotor 13, 14 Rotor shaft 15, 16 Bearing part 17, 18 Space 19, 20 Bearing 24 Oil return flow path 27 Oil return flow path

Continued on the front page (72) Inventor Tomokazu Tashita 2-3-1, Shinhama, Arai-machi, Takasago-shi, Hyogo Prefecture Inside Kobe Steel, Ltd. Takasago Works

Claims (1)

[Claims] 1. A through hole in an outer ring holding sleeve for fixing an outer ring of a bearing facing a free end side space of a discharge side rotor shaft of a male and female screw rotor meshing with each other, and the through hole through the space from the bearing. The oil that has flowed out into the tooth space of the screw rotor, which does not communicate with the discharge port, in the oil-cooled screw compressor. It is made larger than the outer diameter of the intermediate portion between them, and that the through-holes communicate with each other outside this intermediate portion, or that an annular space is formed that communicates the through-hole with the oil return flow path. Characteristic oil-cooled screw compressor.