JP4248055B2 - Oil-cooled screw compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil-cooled compressor having two pairs of male and female rotors, and more particularly to an oil-cooled screw compressor that houses two pairs of rotors in the same casing.
[0002]
[Prior art]
In the conventional oil-cooled two-stage screw compressor, the rotor and casing of the low-pressure stage and the high-pressure stage are arranged in tandem as described in JP-A-8-109887. Further, as described in JP-A-48-21806, a high-pressure stage rotor and a low-pressure stage rotor are accommodated in one casing.
[0003]
[Problems to be solved by the invention]
In an oil-cooled screw compressor configured in two stages, if the rotor and casing of the low-pressure stage and the high-pressure stage are arranged in tandem as described in JP-A-8-109887, the dimension in the rotor axial direction becomes long. It was insufficient in terms of miniaturization of equipment. Moreover, since the rotor shaft is directly connected to the motor, it is difficult to change the set rotational speed of the rotor in the publication described in this publication, and it is necessary to manufacture a rotor with different specifications for each compressor specification. was there.
[0004]
The one described in JP-A-48-21806 has a relatively short dimension in the rotor axial direction, but the discharge directions of the high-pressure stage and the low-pressure stage are opposite, while reversing during assembly, It was necessary to install an angular contact ball bearing that applied a thrust load. Further, when the rotor is extracted from the casing during the maintenance of the compressor, it is necessary to pull out either the high-pressure stage or the low-pressure stage in the direction of the drive shaft, which requires extra work such as moving the prime mover in advance. In particular, the two-stage compressor is generally a large machine of 150 kW or more, and the poor workability leads to a significant increase in maintenance cost.
[0005]
In a two-stage compressor, a low-pressure stage rotor is used for a high-pressure stage rotor of a one-size or two-size large model to achieve common parts. When pinion gears are provided at the shaft ends of the low-pressure stage and the high-pressure stage and each is driven by a common bull gear, it is necessary to reverse the twist directions of the high-pressure stage and the low-pressure stage. For this reason, it is difficult to share the same in designing the rotor series.
[0006]
The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a small and compact two-stage oil-cooled screw compressor. Another object of the present invention is to provide a two-stage oil-cooled screw compressor in which the rotor series design and parts can be easily shared. Still another object of the present invention is to provide a two-stage oil-cooled screw compressor that is easy to maintain.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the first feature of the present invention is that two pairs of a male rotor and a female rotor are housed side by side in the same casing so as to be rotatable, one rotor pair is a low pressure stage, and the other rotor pair is In the oil-cooled screw compressor in which the high pressure stage rotor pair is shorter than the low pressure stage rotor pair , the low pressure stage has a radial direction in which the working gas is sucked, and the high pressure stage has suction direction of the working gas is Ri axial der, the high pressure stage and the low-pressure stage, Ri both discharge direction axial der,
An intermediate stage passage provided in a space sandwiched between the low pressure stage and the high pressure stage and leading discharge gas discharged from the low pressure stage to the high pressure stage, and between the intermediate stage passage and the suction side of the high pressure stage A direction changing portion that changes the direction of the gas that has passed through the intermediate stage passage, a plurality of D casings attached to the discharge side of the casing, and a gear casing attached to the suction side of the casing, The end surfaces on the discharge side of the high-pressure stage and the low-pressure stage are aligned .
[0008]
Preferably, a male rotor and a female rotor pair forming a low pressure stage are horizontally arranged in an upper portion of the casing, the intermediate stage passage is disposed at a lower part of the rotor pair, and a male rotor and a female rotor of a high pressure stage are further provided below the intermediate passage. Pairs are arranged horizontally. More preferably, on the discharge side of the casing, a high-pressure stage D casing that holds a bearing that supports a high-pressure stage rotor pair and a low-pressure stage D casing that holds a bearing that supports a low-pressure stage rotor pair are provided. In the stage D casing, a space for guiding the discharge gas discharged from the low pressure stage to an intermediate stage passage formed in the middle stage of the casing is formed, and a discharge port is formed in the high pressure stage D casing.
[0009]
With this configuration, the rotor axial dimension of the compressor body is significantly shorter than the conventional tandem compressor. Moreover, since the high-pressure stage rotor is generally shorter than the low-pressure stage rotor, the suction port of each stage is provided by utilizing the difference between the rotor lengths of the high-pressure stage and the low-pressure stage, and the axial length is reduced as much as possible. . Furthermore, D casings for accommodating the thrust bearings on the discharge side were separately provided in the high pressure stage and the low pressure stage.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of an oil-cooled two-stage screw compressor according to the present invention, and FIG. 2 is a sectional view taken along line AA in FIG. In the oil-cooled screw compressor, the low pressure stage portion and the high pressure stage portion share a casing. The low-pressure stage portion is disposed in the upper part of the casing 1, and the low-pressure stage male rotor 2 and the low-pressure stage female rotor 3 are rotatably supported by a cylindrical roller bearing 7 on the suction side shaft portion. Further, the shaft portion on the discharge side is rotatably supported by the angular ball bearing 13. These bearings 7 and 13 are held in the casing 1. The working gas sucked into the low-pressure stage is sucked from the radial direction of the rotors 2 and 3 in the low-pressure stage. That is, the suction gas flows from the suction port 6 provided in the upper portion of the casing 1 into the tooth spaces of the rotating low-pressure stage rotors 2 and 3 from the radial direction. In the present embodiment, the axial length of the casing portion corresponding to the suction-side shaft portion of the low-pressure stage rotors 2 and 3 only needs to be a length for attaching the cylindrical roller bearing 7.
[0011]
In screw compressors that suck in gas from the radial direction, if high-temperature discharge side gas and lubricating oil leak from the meshing gap between the rotors into the radial suction port, the temperature of the suction gas is increased to increase volumetric efficiency. May decrease. In this embodiment, since the compression ratio of each stage is reduced as a two-stage compressor, this influence can be almost ignored. Moreover, in a two-stage compressor that is often applied to a large-sized compressor, a large amount of suction gas is handled. Therefore, radial suction is more preferable than an axial suction structure in which the suction gas flow direction needs to be changed by 180 degrees. Low suction resistance. As a result, high suction efficiency can be achieved in a limited space.
[0012]
The working gas sucked into the compressor is injected with lubricating oil in the compression process in the low pressure stage. The working gas compressed in the compression chamber formed by the male rotor 2 and the female rotor 3 of the low pressure stage is supplied to the low pressure stage radial direction discharge port 8 and the low pressure stage D formed on the wall surface of the rotor insertion portion on the low pressure stage side of the casing. The low pressure stage axial discharge port 9 formed on the rotor discharge side end face of the casing 17 exits and flows into the intermediate stage passage 10 which is a space between the low pressure stage and the high pressure stage of the casing.
[0013]
Lubricating oil is also injected into the intermediate stage passage 10 to cool the compressed gas. The intermediate stage passage 10 is formed to correspond to the length of the high-pressure stage rotors 4 and 5. The oil injected with the gas is sufficiently exchanged with heat while flowing through the intermediate stage, the effect of intermediate cooling is increased, and the compressor can achieve high efficiency. The gas cooled in the intermediate stage is changed in the flow direction at the suction port 11 of the high pressure stage, and is sucked into the space formed by the high pressure stage male rotor 4 and the high pressure stage female rotor 5 from the axial direction of the high pressure stage rotor.
[0014]
The high pressure stage portion is disposed at the lower part of the casing 1, and the high pressure stage male rotor 4 and the female rotor 5 are rotatably supported by a cylindrical roller bearing 12 on a suction side shaft portion, and an angular ball bearing 14 is provided on a discharge side shaft. It is supported so that it can rotate freely. Similar to the low-pressure stage, the bearings 12 and 14 are held in the casing 1. Gas that has already been pressurized in the low pressure stage flows into the passage from the intermediate stage to the suction section of the high pressure stage. Therefore, the flow velocity is reduced to about 1/3 of the low-pressure stage suction state or less, and the pressure loss due to the bending of the passage caused in the case of the axial suction can be ignored.
[0015]
In order to change the direction of the gas that has passed through the intermediate stage passage by 180 degrees, a direction changing part is provided on the suction side of the high-pressure stage. This utilizes this difference because the high pressure stage rotor is shorter than the low pressure stage rotor. If the direction changing portion is provided at this location, the end surfaces on the discharge side of the high-pressure stage and the low-pressure stage can be made substantially flush with each other. As a result, the casing can be reduced in size and processed easily.
[0016]
In the compression chamber formed between the male rotor 4 and the female rotor 5 in the high pressure stage, the working gas that has been further pressurized to a predetermined pressure is in the high pressure stage radial direction formed on the wall surface of the rotor insertion portion on the high pressure stage side of the casing 1. It flows out from the discharge port 15 and the high-pressure stage axial direction discharge port 16 formed on the rotor discharge side end face of the high-pressure stage D casing, and is discharged from the discharge port formed in the high-pressure stage D casing 18.
[0017]
In the present embodiment, the suction direction and the discharge direction of the rotor of each stage are made the same, so that the angular ball bearings 13 and 14 bearing the thrust load acting on the rotor are accommodated in the D casing. The D casing is provided separately from the casing that houses the rotor. The low-pressure stage D casing 17 and the high-pressure stage D casing 18 are separated.
[0018]
A low-pressure stage axial discharge port 9 is formed in the low-pressure stage D casing 17, and this discharge port 9 also serves to communicate with the intermediate-stage passage 10 of the casing 1.
[0019]
According to this embodiment, it is possible to disassemble only the high-pressure stage rotors 4 and 5 or only the low-pressure stage rotors 2 and 3. Furthermore, in order to disassemble the rotor, it is only necessary to disassemble one direction opposite to the drive shaft, and the work of extracting the rotor becomes easy. Of course, it is only necessary to assemble the high pressure stage and the low pressure stage from the same direction at the time of assembly, which not only improves the maintenance performance but also reduces the manufacturing cost.
[0020]
Since the high-pressure stage rotor and the low-pressure stage rotor can have similar shapes with the same twisting direction of the rotor, common design of the rotor is easy. Further, a gear transmission means is used to set the rotational speed of the prime mover (not shown) to the rotational speeds of the high-pressure stage and low-pressure stage rotors. The gear transmission means includes a bull gear 19 attached to or formed on the drive shaft 23, and pinion gears 20 and 21 that mesh with the bull gear and obtain a desired speed increase ratio. These gears 19, 20, and 21 are It is covered with a gear casing 22 provided adjacent to the casing 1. The pinion gears 20 and 21 are attached to the male rotor shaft ends of the low pressure stage and the high pressure stage. By appropriately combining the number of teeth of the gears 19, 20, and 21, the number of rotations of the prime mover can be easily set to a desired design number of rotations.
[0021]
【The invention's effect】
According to the present invention, in the oil-cooled screw compressor, since the working gas is sucked from the radial direction in the low pressure stage and the gas is sucked from the axial direction in the high pressure stage, the oil cooling type is highly efficient and compact in the axial direction. A screw compressor is obtained. Further, according to the present invention, an oil-cooled screw compressor that can be easily maintained can be obtained. Furthermore, according to the present invention, it is easy to design a series of rotors, and it is possible to reduce manufacturing costs by sharing parts.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an embodiment of an oil-cooled screw compressor according to the present invention.
2 is an AA cross-sectional view of the oil-cooled screw compressor shown in FIG.
[Explanation of symbols]
1; casing, 2; low-pressure stage male rotor,
3; low-pressure stage female rotor, 4; high-pressure stage male rotor,
5; high-pressure stage female rotor, 6; suction port,
7; Cylindrical roller bearing, 8; Low pressure radial discharge port,
9; Low pressure axial discharge port, 10; Intermediate passage,
11: High-pressure stage suction port, 12: Cylindrical roller bearing,
13; Angular contact ball bearings, 14; Angular contact ball bearings,
15; high-pressure radial discharge port,
16; high-pressure stage axial discharge port,
17; low pressure stage D casing,
18; high-pressure stage D casing,
19; Bull gear, 20; Low-pressure stage pinion gear,
21; high-pressure stage pinion gear, 22; gear casing,
23; drive shaft, 24; oil seal,
25; Bearing.

Claims (3)

The pair of male and female rotors within the same casing housed side by side in a freely 2 sets rotation, one rotor pair the low pressure stage, the other rotor pair is formed a high-pressure stage, the high-pressure stage of the twin rotors are said low pressure In an oil-cooled screw compressor shorter than the stage rotor pair ,
Said low pressure stage is a suction direction radial of the working gas, the high pressure stage Ri suction direction axial der of the working gas,
In both the high pressure stage and the low pressure stage, the discharge direction is the axial direction,
An intermediate stage passage provided in a space sandwiched between the low pressure stage and the high pressure stage, and leading discharge gas discharged from the low pressure stage to the high pressure stage;
A direction changing portion that is located between the intermediate stage passage and the suction side of the high pressure stage and changes the direction of the gas that has passed through the intermediate stage passage;
A plurality of D casings attached to the discharge side of the casing;
A gear casing attached to the suction side of the casing;
An oil-cooled screw compressor characterized in that end faces on the discharge side of the high-pressure stage and the low-pressure stage are aligned . The male rotor and female rotor pair forming the low pressure stage are horizontally arranged at the upper part of the casing, the intermediate stage passage is disposed at the lower part of the rotor pair, and the male rotor and female rotor pair of the high pressure stage is further provided at the lower part thereof. The oil-cooled screw compressor according to claim 1, wherein the oil-cooled screw compressor is arranged horizontally. On the discharge side of the casing, a high-pressure stage D casing that holds a bearing that supports a high-pressure stage rotor pair and a low-pressure stage D casing that holds a bearing that supports a low-pressure stage rotor pair are provided. to claim 1, which forms a space which leads to the intermediate stage passage formed a discharge gas discharged from the low pressure stage to the middle stage of the casing, the high pressure stage D casing is characterized by the formation of the discharge ports Or the oil-cooled screw compressor of 2 .

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