JP2013047526A - Screw compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a mass flow rate of a working gas in a screw compressor by suppressing a scattering amount of liquid to a suction port.SOLUTION: In the screw compressor, a male-and-female pair of rotors having a twisted lobe are engaged with each other and rotate, a gas shut in a working space 5 formed by both of the rotors and a casing is compressed while the liquid is poured into the gas, and a beam 7 is provided, in particular, between the suction port 3 and a gap 6 between the male-and-female rotors. A distance from the center line 8 of an engagement part to an end on a male rotor 2 of the beam 7 is longer than a distance from the center line 8 of the engagement part to an end on a female rotor 1 of the beam 7.

Description

  The present invention relates to a screw compressor that injects a liquid into a working space and compresses a gas in a state where the liquid is mixed.

  FIG. 3 shows a cross-sectional view of a suction side wall inside a casing of a conventional screw compressor. In the screw compressor, a pair of female rotor 1 and male rotor 2 that mesh with each other are accommodated in a cylindrical space 4 in the casing. The working gas that has flowed into the casing from the suction port 3 is injected with liquid for the purpose of cooling the compressed air and sealing the gap between the working chambers in the tooth spaces acting as the working space 5 as the male and female rotors rotate. Compressed while being discharged through a discharge port (not shown in the figure).

  One of the two spaces adjacent to each other with the gap 6 between the male and female rotors is at the discharge pressure, and the other is at the suction pressure. Therefore, the liquid injected into the working space 5 mixed with the compressed working gas is scattered from the working space 5 at the discharge pressure to the space at the suction pressure through the gap 6 between the male and female rotors. At this time, since the liquid is mixed with the working gas flowing in from the suction port 3, the pressure loss of the working gas in the suction process increases. Moreover, since the liquid which is scattered is high temperature, when the liquid is mixed in the working gas flowing in from the suction port 3, the temperature of the working gas rises, which causes a decrease in the mass flow rate of the working gas.

  Japanese Patent Application Laid-Open No. 38-9388 discloses a screw compressor characterized in that a V-shaped beam is provided between a suction port and a gap between both male and female rotors to disperse scattered liquid from the suction port. is suggesting. Further, in the above-mentioned patent document, it is intended to remove the scattered liquid from the casing by providing the casing inner wall or the beam when collecting the oil diverted from the suction port, and connecting each collector to the discharge port. .

JP-A-38-9388

  With the technique of the above-mentioned patent document 1, it is possible to prevent the liquid from being scattered to the suction port by a beam or the like provided inside the casing. However, in the above-mentioned patent document, the influence of the shape of the beam is not sufficiently taken into consideration for the pressure loss in the working gas suction process. In other words, when the beam is enlarged in order to enhance the liquid scattering prevention effect, there is a concern that the flow resistance of the beam itself with respect to the working gas in the suction process increases, and the suction process is hindered. In addition, when the structure of the soot provided in the casing or the liquid discharge port becomes complicated, there is a greater concern about an increase in flow resistance against the working gas due to an increase in the size of the beam.

  The object of the present invention is to prevent the liquid splashed from the gap between the male and female rotors from mixing with the working gas flowing in from the suction port, and to minimize the flow resistance of the beam itself against the working gas in the suction process. Is to propose a simple casing structure.

  In order to achieve the above object, in the present invention, the beam is formed in a concave shape between the male and female rotors at the portion in contact with the suction side end surface, and at least one of the male rotor and the female rotor on the suction side wall surface inside the casing A groove that communicates the space below the beam and the working space before the compression process is provided in a portion in contact with the side end face.

  According to the present invention, it becomes possible to prevent the mixing of oil and working gas scattered from the gap between the male and female rotors without hindering the process of sucking the working gas of the screw compressor, so that the mass flow rate of the working gas is increased. It becomes possible to do.

It is a schematic diagram of the screw compressor which shows 1st Example of this invention. It is a schematic diagram of the seal line in 1st Example of this invention. It is a schematic diagram of the conventional common screw compressor. It is a schematic diagram of the screw compressor which shows 2nd Example of this invention. It is a schematic diagram of the screw compressor which shows 3rd Example of this invention. It is a schematic diagram of the screw compressor which shows 3rd Example of this invention. It is a schematic diagram of the screw compressor which shows 3rd Example of this invention.

  A first embodiment of the present invention will be described below with reference to FIG. In addition, a present Example is related with the oil supply type screw compressor which uses oil as the liquid inject | poured in a working space.

  FIG. 1 is a cross-sectional view of a rotor suction side wall surface inside a casing of an oil compression type oil compressor for air compression. In the figure, reference numerals 1 and 2 denote a pair of female and male rotors that mesh with each other, and air is sucked from the suction port 3 as the male and female rotors rotate.

  After being sucked in from the suction port 3, the air sealed in the working space 5 formed by the tooth spaces of the female rotor 1 and the male rotor 2 and the cylindrical space 4 of the casing is moved into the working space 5 by the rotation of the male and female rotors. Compressed with volume reduction.

  The air compressed to the set pressure as the volume of the working space 5 is reduced is discharged from the discharge port (not shown) to the outside of the compressor. In the air compression process, oil is injected from the outside of the casing for the purpose of sealing the gap in the working space 5 that causes air cooling and internal leakage.

  The oil injected into the working space 5 in the air compression process becomes a high temperature and high pressure state in the compression process, and scatters from the gap 6 between the male and female rotors toward the suction port 3.

  At this time, if the scattered oil is mixed with the air flowing in from the suction port 3, not only the pressure loss of the air in the suction process increases, but also the temperature of the air in the suction process increases due to heat exchange with the scattered oil. And the mass flow rate of air will fall. Therefore, a beam 7 is provided between the suction port 3 and the gap 6 between the male and female rotors. Here, a straight line passing through the intersection of the cylindrical portions of the casing and orthogonal to a line connecting the centers of the male and female rotors is defined as a center line 8 of the meshing portion of the male and female rotors.

  FIG. 2 is a locus of contact points between the male and female rotors when the female rotor 1 and the male rotor 2 are rotated once. This locus is hereinafter defined as a seal line 9. In the figure, a tangent vector 10 on the tooth surface of the male rotor 2 orthogonal to the male rotor 2 and the seal line 9 is also shown. The tangent vector 10 means the oil scattering direction, and since the portion closer to the inlet 3 on the seal line 9 particularly faces the male rotor 2, most of the oil scattered from the gap 6 between the male and female rotors. Can be seen to scatter in the direction of the male rotor 2.

  Accordingly, in FIG. 1, the shape of the beam 7 that has been generally symmetric with respect to the center line 8 in the prior art is determined by the distance from the center line 8 to the end of the beam 7 on the female rotor 1 side. Increase the distance to the two side edges. Thereby, not only can the mixing amount of the oil splashed from the gap 6 between the male and female rotors to the male rotor 2 side and the air flowing from the suction port 3 be reduced, but the distance from the center line 8 to the end of the beam 7 on the female rotor 1 side can be reduced. By minimizing the distance, it is possible to minimize the obstruction of the air suction process due to the shape of the beam 7 itself.

  In addition, the position of the end of the beam 7 on the male rotor 2 side is opposite to the female rotor 1 with respect to the male center line 11 passing through the center of the male rotor 2 and perpendicular to the line connecting the centers of the male and female rotors. Provide. Thereby, it is possible to prevent the oil accumulated in the space between the beam 7 and the gap 6 between the male and female rotors from flowing around the beam 7 by the rotational movement of the male rotor 2 and splashing again toward the suction port 3. . Further, a passage 12 that communicates the inside and the outside of the casing is provided on the casing suction side wall surface between the beam 7 and the gap 6 between the male and female rotors. By connecting the passage 12 and the working space 13 in the suction process using an external pipe, the negative pressure in the working space 13 in the suction process accumulates in the space between the beam 7 and the gap 6 between the male and female rotors. The oil can be removed without being scattered toward the suction port 3 and recovered in the working space 13.

  As described above, since the amount of oil scattered from the male-male rotor gap 6 toward the suction port 3 is reduced, an oil-cooled screw compressor effective for increasing the mass flow rate can be realized.

  Hereinafter, a second embodiment of the present invention will be described with reference to FIG.

  The difference between the present embodiment and the first embodiment is that, instead of the passage 12 provided on the casing suction side wall surface, a portion of the casing suction side wall surface that is in contact with the suction side end surfaces of the male and female rotors is formed between the beam 7 and the male and female rotors. The groove 14 is provided to communicate the space between the gap 6 and the working space 13 in the suction process, and the beam 7 is formed in a concave shape toward the gap 6 between the male and female rotors. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

  With the configuration shown in the present embodiment, the scattered oil can be easily held between the beam 7 and the gap 6 between the male and female rotors, and an effect equivalent to that of the passage 12 can be obtained without using external piping. . The oil splashed from the gap 6 between the male and female rotors is held in the concave portion of the beam 7 and passes through the passage formed by the groove 14 and the suction side end surfaces of the male and female rotors due to the negative pressure of the working space 13 in the suction process. 7 is removed from the space between the male and female rotor gap 6 and recovered in the working space 13. As a result, an oil-cooled screw compressor effective for increasing the mass flow rate can be realized by a simpler method than in the first embodiment.

  Hereinafter, a third embodiment of the present invention will be described with reference to FIG. 5, FIG. 6, and FIG. 5 is a cross-sectional view of the suction side wall inside the casing of the screw compressor in the present embodiment, FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5, and FIG. 7 is a front view of FIG. It corresponds to the plan view.

  This embodiment differs from the first embodiment in that instead of the passage 12 provided on the casing suction side wall surface, the surface of the beam 7 facing the space between the beam 7 and the gap 6 between the male and female rotors, and the casing The passage 15 communicating with the outside is provided inside the beam 7, and as shown in FIG. 7, the width of the beam 7 is reduced from the casing discharge side wall surface toward the suction side wall surface. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

  With the configuration shown in this embodiment, it is possible to remove more oil scattered from the gap 6 between the male and female rotors than in the first embodiment, and to reduce the flow resistance of the beam 7 itself against the working gas in the suction process. . The pressure difference between two spaces adjacent to each other with the gap 6 between the male and female rotors increases from the suction side wall surface toward the discharge side wall surface inside the casing. Therefore, the portion closer to the discharge side wall surface increases the width of the beam 7 to prevent oil scattering, while the portion closer to the suction side wall surface reduces the amount of oil scattering, so reducing the width of the beam 7 reduces the suction. The flow resistance of the beam 7 itself against the air in the process can be reduced. Further, the opening of the passage 15 for the purpose of oil removal was provided on the surface of the beam 7 closer to the discharge side wall surface where the amount of oil scattered was large, and further the passage 15 was provided inside the beam, thereby scattering. It is possible to prevent the oil from returning to the tooth grooves of the female rotor 1 and the male rotor 2 and scattering into the casing due to the rotational movement of both the male and female rotors.

  As described above, the amount of oil scattered in the casing and the pressure loss of air in the suction process can be reduced as compared with the first embodiment, and an oil-cooled screw compressor effective for increasing the mass flow rate can be realized. Become.

DESCRIPTION OF SYMBOLS 1 Female rotor 2 Male rotor 3 Suction port 4 Cylindrical space 5 Casing space 6 Working space 6 Gap between male and female rotors 7 Beam 8 Centerline 9 of meshing part of male and female rotor 9 Seal line 10 Tangent vector 11 of seal line Male side centerline 12 Passage 13 Working space in suction process 14 Groove 15 Passage

Claims (1)

  A pair of male and female rotors with twisted lobes rotate in mesh with each other, compressing while injecting liquid into the gas confined in the working space formed by both rotors and the casing, especially the inlet and the male and female rotors In a screw compressor in which a beam is provided between the meshing portion, a beam is formed in a concave shape toward a portion between the male and female rotors at a portion in contact with the suction side end surface, and the male rotor or the female rotor on the suction side wall surface inside the casing. A screw compressor characterized in that a groove is provided in a portion in contact with at least one of the suction side end faces to communicate the space below the beam and the working space before the compression process.