JP2011069309A - Screw compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw compressor increasing a mass flow rate of fluid sucked. <P>SOLUTION: This screw compressor sucking fluid from a suction opening, compressing the sucked fluid, and delivering the compressed fluid from a delivery passage to the outside includes: a male rotor and a female rotor engaged with each other; a rotating shaft provided to each of the male rotor and female rotor; and a casing storing at least the male rotor and female rotor. A width between the inner wall surface of the casing and at least one periphery of the male rotor and the female rotor is reduced from the suction opening toward a delivery side in a rotating shaft direction. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a screw compressor.

  FIG. 2 shows a cross-sectional view between the male rotor and the female rotor of the screw compressor that sucks fluid from the outer peripheral surface and the end surface of the male rotor and the female rotor. The screw compressor includes a casing 1 having a cylindrical space and a pair of a male rotor 2 and a female rotor (not shown) housed in the casing 1 so as to mesh with each other.

  The fluid that has flowed into the casing 1 from the suction port 3 due to the rotation of the rotation shaft of the male rotor and the rotation shaft of the female rotor is between the suction port 5 and the discharge side end surfaces of the male rotor 2 and the female rotor. 2 is compressed in the working space formed by the female rotor 2 and the casing 1, and is discharged to the outside through the discharge passage 4.

  When the suction port 5 is opened on the outer peripheral surfaces of the male rotor 2 and the female rotor, the centrifugal force acts on the fluid in the suction process by both rotating rotors, leading to a decrease in pressure in this working space, It causes the mass flow rate to decrease.

  Patent Document 1 discloses a configuration in which the diameter of the rotor and the shape of the spiral blade in each part of the working space are changed at the same time for an apparatus having a spiral blade that cooperates. In addition, a configuration is disclosed in which the rotor diameter and the diameter of the rotation accommodating portion are gradually narrowed from the rotor axial inlet side toward the outlet side.

  Patent Document 2 discloses a twin screw compression mechanism having an automatic gap adjustment function using a pressure difference, in which the volume of at least one air chamber formed by surrounding the root of the screw thread, the side wall, and the inner ring wall is larger than the outlet end of the case. A configuration that gradually decreases toward the edge is disclosed.

  In Patent Literature 3, regarding a screw fluid machine, a coating layer made of a material different from that of a casing is provided in a portion near the discharge port of the bore wall surface, and the thickness of the coating layer is gradually increased from the suction port side toward the discharge port side. Increasing configurations are disclosed.

  Patent Document 4 discloses a configuration relating to a screw fluid machine, in which a coating layer made of a material different from that of a casing is applied to the entire surface of the bore, and the thickness is increased near the discharge port on the high-pressure side bore surface and becomes thinner as it is further away. Has been.

Japanese translation of PCT publication No. 2003-522889 JP 2001-214874 A JP 05-231362 A Japanese Patent Laid-Open No. 04-214980

  Patent Document 1 aims to increase the efficiency of the compression process and stabilize the operation characteristics. Further, Patent Document 2 aims to automatically adjust the internal pressure of the working space to reduce the starting power and the starting current to prevent the motor from being overloaded and to make the operation more stable. Patent Document 3 and Patent Document 4 aim to reduce internal leakage of fluid during the compression process and improve compressor efficiency. However, nothing is mentioned about increasing the mass flow rate by reducing the pressure loss in the suction process.

  An object of the present invention is to provide a screw compressor capable of increasing the mass flow rate of a sucked fluid.

  In order to solve the above problems, the present invention relates to a male and female rotor meshed with each other in a screw compressor that sucks and compresses fluid from a suction port and discharges the compressed fluid from a discharge passage to the outside. A rotating shaft provided in each of the male rotor and the female rotor, and a casing in which at least the male rotor and the female rotor are housed, and an inner wall surface of the casing and the male rotor or the female rotor The width with respect to at least one of the outer circumferences is formed in the direction of the rotation axis so as to decrease from the suction port toward the discharge side. Furthermore, the inner wall surface of the casing is formed closer to the suction port than the discharge passage. Further, in a screw compressor that sucks and compresses fluid from a suction port and discharges the compressed fluid to the outside from a discharge passage, each of the male rotor and the female rotor engaged with each other, and each of the male rotor and the female rotor A rotating shaft provided; and a casing in which at least the male rotor and the female rotor are housed; and at least a part of the inner wall surface of the casing, the inner wall surface of the casing and the male rotor or the female rotor. The width with respect to at least one of the outer circumferences is formed in the direction of the rotation axis so as to decrease from the suction port toward the discharge side. Furthermore, a groove is provided in at least a part of the inner wall surface of the casing in a direction away from the male rotor or the female rotor. Furthermore, it is provided in the vicinity of the end surface on the suction side of the fluid of the casing, and includes a passage that communicates the inside and the outside of the casing. Furthermore, the inner wall surface of the casing is formed closer to the suction port than the discharge passage.

  ADVANTAGE OF THE INVENTION According to this invention, the screw compressor which can increase the mass flow rate of the inhaled fluid can be provided.

It is a figure which shows the cross section of the screw compressor of Example 1. FIG. It is sectional drawing parallel to the rotor axis | shaft of a screw compressor. It is a figure which shows the AA cross section of FIG. 3 is a schematic diagram of a screw compressor of Example 2. FIG. It is a figure which shows the AA cross section of FIG.

  Hereinafter, Example 1 is demonstrated using FIG. 1, FIG. The first embodiment relates to a compressor that compresses, for example, air as a fluid.

  FIG. 1 is a diagram illustrating a cross section between the male rotor 2 and the female rotor of the screw compressor of the first embodiment. The main structure of the screw compressor of Example 1 is the same as that of FIG.

  The fluid that has flowed into the casing 1 from the suction port 3 is compressed in the working space formed by the male rotor 2, the female rotor, and the casing 1 between the suction port 5 and the discharge-side end surfaces of both rotors. Then, it is discharged to the outside through the discharge passage 4.

  When the suction port 5 is open to the outer peripheral surfaces of both rotors, the centrifugal force acts on the fluid in the suction process by both rotating rotors, causing a pressure drop in the working space and causing a decrease in mass flow rate. Become.

  Therefore, in the first embodiment, in the casing 1, the inner wall surface 6 upstream of the suction port 5 is inclined with respect to the shafts of the two rotors, and the suction flow path formed by the inner wall surface 6 and the outer peripheral surfaces of the two rotors. The width is reduced toward the discharge side in the axial direction of both rotors. That is, at least a part of the inner wall surface 6 of the casing 1 has a width between the inner wall surface 6 of the casing 1 on the upstream side of the fluid and the outer periphery of at least one of the male rotor 2 and the female rotor. It is formed so as to be larger than the width between the inner wall surface of 1 and the outer periphery of at least one of the male rotor 2 and the female rotor. Further, the width between the inner wall surface of the casing 1 and the outer periphery of at least one of the male rotor 2 and the female rotor is formed so as to decrease in the rotation axis direction from the suction port 3 toward the discharge side. Further, the inner wall surface 6 of the casing 1 is formed such that the width of the outer periphery of at least one of the inner wall surface of the casing on the upstream side and the male rotor 2 or the female rotor decreases from the upstream side toward the downstream side. . The inner wall surface 6 is formed closer to the suction port 3 than the discharge passage 4.

  This prevents the fluid once sucked into the working space from being discharged outside the working space from between the outer peripheral surface of the both rotors and the inner wall surface 6 by the centrifugal force acting on the fluid as both rotors rotate. Is possible. If the distance between the inner wall surface 6 and the inlet 3 of the rotor is reduced, the distance between the inner wall surface 6 and the outer peripheral surfaces of the two rotors becomes a factor that hinders the suction process and increases the pressure loss. Make it as large as possible.

  3 is a cross-sectional view taken along the line AA in FIG. 2 of the first embodiment. In FIG. 3, the inner wall surface 6 is formed so that the width of the suction flow path formed by the inner wall surface 6 of the casing 1 and the outer peripheral surfaces of both rotors is narrowed in the rotation direction of each of the rotors. Thereby, like the above description, there is an effect of preventing a pressure drop in the working space.

  As described above, according to the screw compressor of the first embodiment, the flow rate of the fluid can be increased.

  Further, the centrifugal force acting on the fluid accompanying the rotation of both rotors prevents the fluid once sucked into the working space from being discharged out of the working space from the gap between the outer peripheral surface of both rotors and the inner wall surface of the casing. As a result, it is possible to realize a screw compressor that is effective in increasing the flow rate of fluid.

  Next, Example 2 will be described with reference to FIGS. The second embodiment relates to an oil-cooled compressor that compresses, for example, air as a fluid and supplies lubricating oil from the outside into the working space in the compression process.

  The difference between the second embodiment and the first embodiment will be described. In the second embodiment, an oil supply hole 7 for supplying lubricating oil from the outside into the working space is provided. Further, a portion (groove) 8 in which the width of the suction flow path formed by the inner wall surface 6 upstream of the suction port 5 and the outer peripheral surfaces of both rotors in the casing 1 suddenly expands in the rotation direction of both rotors is defined as the inner wall surface 6. Is formed. That is, the groove 8 is at least a part of the inner wall surface of the casing 1 and is provided in a direction away from the male rotor 2 or the female rotor. Further, a passage 9 is provided in the vicinity of the suction port 5 on the suction side end face of the casing 1 to communicate the inside of the casing 1 and the bearing chamber. Since others are the same as those of the first embodiment, the same reference numerals are given and the description thereof is omitted.

  In the second embodiment, as in the first embodiment, the width of the suction flow path formed by the inner wall surface 6 and the outer peripheral surfaces of the two rotors is made smaller toward the discharge side in the axial direction of both rotors and in the rotational direction. ing. That is, the width between the inner wall surface of the casing 1 and the outer periphery of at least one of the male rotor 2 and the female rotor is formed in the direction of the rotation axis so as to decrease from the suction port 3 toward the discharge side. As a result, the fluid once sucked into the working space can be prevented from flowing out of the working space again due to the centrifugal force acting on the fluid as the two rotors rotate.

  Further, in the oil-cooled compressor, a phenomenon occurs in which the lubricating oil supplied to the working space in the compression process flows backward through the gaps and is scattered from the suction port 5. Lubricating oil scattered from the suction port 5 receives centrifugal force as the rotors rotate, and flows backward on the inner wall surface 6 toward the suction port 3. This phenomenon not only increases the pressure loss of the fluid in the suction process, but also expands the fluid in the suction process by exchanging heat with high-temperature lubricating oil, leading to a decrease in mass flow rate.

  Therefore, the inner wall surface 6 is provided with a groove 8 in which the width of the suction flow path formed by the inner wall surface 6 on the upstream side of the suction port 5 of the casing 1 and the outer peripheral surfaces of both rotors suddenly expands in the rotation direction of both rotors. Form. Further, a passage 9 is provided in the vicinity of the suction port 5 on the suction side end face of the casing 1 to connect the inside of the casing 1 and the bearing chamber. That is, the passage 9 is provided in the vicinity of the fluid suction side end surface of the casing 1.

  As a result, the lubricating oil that scatters from the suction port 5 and flows backward on the inner wall surface 6 is blocked by the portion (groove) 8 where the suction flow path suddenly expands, and then on the suction side end surface of the casing 1 by gravity. It collects in the vicinity of the suction port 5. Thereafter, the air is discharged into the bearing chamber through a passage 9 that connects the inside of the casing 1 and the bearing chamber. Therefore, it is possible to prevent the fluid flowing in from the suction port 3 and the lubricating oil scattered from the suction port 5 from interfering with each other, and to obtain the effect of reducing the pressure loss of the fluid and preventing the expansion due to heat exchange with the lubricating oil. it can.

  As described above, even in the oil-cooled screw compressor having the suction port opening on the outer peripheral surface of the rotor, it is possible to reduce the pressure loss in the suction process and realize a compressor effective in increasing the mass flow rate of the fluid. .

DESCRIPTION OF SYMBOLS 1 Casing 2 Male rotor 3 Suction port 4 Discharge passage 5 Suction port 6 Inner wall surface of the casing upstream from the suction port 7 Oil supply hole 8 Groove 9 A passage that communicates the inside and outside of the casing

Claims (6)

In a screw compressor that sucks and compresses fluid from a suction port and discharges the compressed fluid to the outside from a discharge passage,
A male rotor and a female rotor meshing with each other;
A rotation shaft provided in each of the male rotor and the female rotor;
At least a casing in which the male rotor and the female rotor are housed,
The width between the inner wall surface of the casing and the outer periphery of at least one of the male rotor and the female rotor is in the direction of the rotation axis, and is formed so as to decrease from the suction port toward the discharge side. A screw compressor characterized by that.   The screw compressor according to claim 1, wherein an inner wall surface of the casing is formed closer to the suction port than the discharge passage. In a screw compressor that sucks and compresses fluid from a suction port and discharges the compressed fluid to the outside from a discharge passage,
A male rotor and a female rotor meshing with each other;
A rotation shaft provided in each of the male rotor and the female rotor;
At least a casing in which the male rotor and the female rotor are housed,
In at least a part of the inner wall surface of the casing, the width between the inner wall surface of the casing and the outer periphery of at least one of the male rotor and the female rotor is in the direction of the rotation axis, and is discharged from the suction port. A screw compressor characterized by being formed so as to become smaller toward the side. The screw compressor according to claim 3,
A screw compressor, wherein a groove is provided in at least a part of an inner wall surface of the casing in a direction away from the male rotor or the female rotor. The screw compressor according to claim 3,
A screw compressor, comprising a passage provided in the vicinity of an end surface on the suction side of the fluid of the casing and communicating the inside and the outside of the casing.   The screw compressor according to claim 3, wherein an inner wall surface of the casing is formed closer to the suction port than the discharge passage.

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