JP6276117B2 - Compressor and manufacturing method of compressor - Google Patents

Description

  The present invention relates to a compressor and a method for manufacturing the compressor.

  Conventionally, a compressor that compresses gas by rotation of an impeller is known. Patent Document 1 below discloses an example of such a compressor.

  The centrifugal compressor disclosed in Patent Document 1 includes a casing and an impeller that is rotatably provided in the internal space of the casing.

  The casing has a tapered inner peripheral surface that increases in diameter as it goes from one end in the axial direction of the impeller toward the other end. The impeller includes a plurality of blades extending toward the inner peripheral surface of the casing. Each blade has an outer edge that faces the inner peripheral surface of the casing. A minute gap is formed between the inner peripheral surface of the casing and the outer edge of each blade.

  A spiral chamber is provided on the outer peripheral portion of the casing, and a flow path in which a diffuser is disposed between the housing space of the impeller and the spiral chamber is provided. The gas compressed by the rotation of the impeller flows into the spiral chamber through the flow path in which the diffuser is disposed, and is discharged from the compressor.

Japanese Utility Model Laid-Open No. 5-12593

  Since the casing of the compressor is generally formed of a casting such as cast iron or cast steel, corrosion tends to occur on the inner peripheral surface due to moisture contained in the gas to be compressed. In the conventional compressor, when corrosion occurs on the inner peripheral surface of the casing, a shroud gap, which is a gap between the inner peripheral surface of the casing and the outer edge of each blade, is enlarged, and the performance of the compressor is reduced. .

  The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress deterioration in the performance of the compressor due to corrosion of the casing.

  In order to achieve the above object, a compressor according to the present invention includes a casing, an impeller rotatably provided in the casing, a flow rate of gas compressed in the casing and compressed by the impeller. The impeller includes a blade extending toward an inner peripheral surface of the casing, and the diffuser includes a shroud forming portion that forms at least a part of a shroud surface facing the blade. And the said shroud formation part consists of a raw material with higher corrosion resistance than the raw material of the said casing.

  In this configuration, the shroud formation part made of a material that is more resistant to corrosion than the material of the casing forms at least a part of the shroud surface, so that expansion of the shroud gap between the shroud surface and the blade due to corrosion of the casing is suppressed. it can. For this reason, the performance fall of a compressor can be controlled. Further, since the corrosion resistance can be enhanced by using the shroud forming portion of the diffuser, for example, an increase in manufacturing cost can be suppressed as compared with a case where the entire casing is formed of a material having high corrosion resistance.

  In the compressor, the inner peripheral surface of the shroud forming part preferably forms the continuous shroud surface together with the inner peripheral surface of the casing.

  According to this configuration, a smooth continuous shroud surface can be formed by the casing and the shroud forming portion of the diffuser.

  In the compressor, the casing has an internal space for accommodating the impeller, and the shroud forming portion forms the shroud surface at an outlet of the internal space from which the compressed gas is discharged. preferable.

  Although the shroud gap enlarged due to the corrosion of the casing is difficult to repair, the shroud gap enlarged due to the distortion of the casing can be repaired by adjustment. For this reason, according to this configuration, the shroud surface at the outlet of the internal space is formed by the shroud forming portion having high corrosion resistance, so that the expansion of the shroud gap due to corrosion difficult to repair is formed at the outlet of the internal space. The cause of the expansion of the shroud gap can be limited to that caused by easily adjustable distortion.

  The compressor has a gear and a speed increaser casing in which the gear is arranged, and includes a speed increaser that increases the rotational force of a motor and transmits the speed to the impeller, and the speed increaser casing side of the internal space It is preferable to provide a casing cover that covers the end of the casing, and a shim that is sandwiched between the speed increaser casing and the casing cover.

  According to this configuration, even if the shroud gap may be enlarged due to distortion of any one of the compression portion casing, the casing cover, and the speed increaser casing due to secular change, it can be repaired by adjusting the thickness of the shim.

  In the compressor, the material of the shroud forming part is preferably stainless steel.

  Since the casing of the compressor is generally formed of a cast material such as cast iron or cast steel, the material of the shroud forming portion is stainless steel, so that a shroud forming portion having higher corrosion resistance than the casing can be formed.

  The method for manufacturing a compressor according to the present invention is a method for manufacturing the compressor, wherein the inner peripheral surface of the casing and the inner peripheral surface of the shroud forming portion in a state where the shroud forming portion is coupled to the casing. It is equipped with a cutting process that cuts out at the same time.

  According to this manufacturing method, a smooth shroud surface without a step can be easily formed between the inner peripheral surface of the casing and the inner peripheral surface of the shroud forming portion.

  ADVANTAGE OF THE INVENTION According to this invention, the performance fall of the compressor by corrosion of a casing can be suppressed.

1 is a partial cross-sectional view of a turbo compressor according to an embodiment of the present invention. It is an enlarged view of the A section in FIG. It is sectional drawing of a compression part casing. It is the top view which looked at the compression part casing from the casing cover side. It is a top view of a diffuser. It is sectional drawing along the axial direction of a diffuser.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a partial cross-sectional view of the turbo compressor according to the present embodiment. The compressor according to the present embodiment includes an unillustrated motor, a speed increaser 2, a compressor casing 4, a casing cover 6, an impeller 8, a diffuser 10, and a shim 11.

  The speed increaser 2 increases the rotational force of a motor (not shown) and transmits it to the impeller 8. The speed increaser 2 includes a low speed shaft (not shown), a low speed gear 12, a high speed gear 14, a high speed shaft 16, and a speed increaser casing 18. The low speed gear 12 is externally fitted to a low speed shaft (not shown) and is disposed in the speed increaser casing 18. The high speed gear 14 is provided on the high speed shaft 16 and meshes with the low speed gear 12. The left end of the high speed shaft 16 in FIG. 1 protrudes from the gear box casing 18 and is coupled to the impeller 8.

  As shown in FIG. 1, the compression section casing 4 is fastened to the speed increaser casing 18 via the casing cover 6 and the shim 11. In this embodiment, the compression part casing 4 corresponds to the casing of the present invention. The compression part casing 4 is formed by castings, such as cast iron and cast steel. The compression section casing 4 includes a storage section 22 that stores the impeller 8, and a scroll section 24 that is disposed on the outer periphery of the storage section 22 and formed integrally with the storage section 22.

  An internal space 22 a in which the impeller 8 is disposed is provided in the housing portion 22. Both ends of the internal space 22a in the axial direction of the high speed shaft 16 are open. Hereinafter, the term “axial direction” simply refers to the axial direction of the high-speed shaft 16. The radial direction around the high-speed shaft 16 is simply referred to as “radial direction”. The casing cover 6 covers the end portion of the internal space 22a on the speed increaser casing 18 side. A gas inlet 22b is configured by the end of the internal space 22a opposite to the casing cover 6.

  FIG. 2 is an enlarged view of a portion A in FIG. As shown in FIG. 2, the inner peripheral surface 22c of the accommodating portion 22 forming the internal space 22a has an inlet side tapered surface 22d, an intermediate surface 22e, and an outlet side tapered surface 22f.

  The inlet side tapered surface 22d, the intermediate surface 22e, and the outlet side tapered surface 22f are sequentially arranged from the introduction port 22b to the casing cover 6 side. An inner peripheral surface 22c from the inlet-side tapered surface 22d to the intermediate surface 22e has a tapered shape with a diameter decreasing toward the casing cover 6 side. The outlet-side tapered surface 22f has a tapered shape whose diameter increases toward the casing cover 6 side. An edge 22g on the casing cover 6 side of the outlet side tapered surface 22f corresponds to an edge on the casing cover 6 side of the inner peripheral surface 22c.

  FIG. 3 is a sectional view along the axial direction of the compression section casing 4 alone. The compression part casing 4 has the fitting recessed part 25 formed in the outer periphery of the edge part 22g of 22 f of exit side taper surfaces. The fitting recess 25 is a circular recess formed coaxially with the inner peripheral surface 22c when viewed in the axial direction.

  The scroll portion 24 is disposed on the radially outer side of the fitting recess 25. The scroll unit 24 is provided with a spiral chamber 24a from which compressed gas is discharged. The scroll portion 24 has an end surface 24 b that extends radially outward from the outer edge of the fitting recess 25. The end surface 24b is perpendicular to the axial direction, and is disposed with a gap between the end surface 24b and the casing cover 6 as shown in FIG.

  FIG. 4 is a plan view of the compression section casing 4 as viewed from the casing cover 6 side. The outer peripheral part of the scroll part 24 has the outer peripheral end surface 24d which contact | abuts on the casing cover 6 (refer FIG. 2). The outer peripheral end face 24d is disposed perpendicular to the axial direction. A circular ring groove 24e into which a sealing O-ring 50 (see FIG. 2) is fitted is formed on the outer peripheral end surface 24d. As shown in FIG. 4, the ring groove 24 e is disposed so as to have a center O <b> 2 at a position eccentric from the axis O <b> 1 of the housing portion 22. By arranging the ring groove 24e eccentrically, a notch portion 24g recessed inward in the radial direction is provided in a region located on the outer peripheral portion of the scroll portion 24. The notch portion 24g avoids interference between the compression portion casing 4 and a direct connection pump (not shown) connected to the compressor (in the present embodiment, located immediately above the scroll portion 24 in FIG. 1).

  As shown in FIG. 1, the impeller 8 is accommodated in an internal space 22 a of the accommodating portion 22 and is provided to be rotatable around an axis. The impeller 8 is an example of the impeller of the present invention. The impeller 8 has a hub 26 and a plurality of blades 28.

  As shown in FIG. 1, the hub 26 is coupled to the high speed shaft 16 while being arranged coaxially with the high speed shaft 16. The hub 26 has an outer peripheral surface 26b that expands radially outward from the top portion 26a toward the casing cover 6.

  The plurality of blades 28 protrude from the outer peripheral surface 26 b of the hub 26 toward an inner peripheral surface 22 c of the accommodating portion 22 and an inner peripheral surface 32 a of the disk portion 32 described later. The plurality of blades 28 are arranged at intervals in the circumferential direction of the hub 26. The plurality of blades 28 and the hub 26 are integrally formed of a metal material. As shown in FIG. 2, each blade 28 has an outer end edge 28 a that extends radially outward toward the casing cover 6 side.

  FIG. 5 is a plan view of the diffuser 10, and FIG. 6 is a cross-sectional view along the axial direction of the diffuser 10. As shown in FIGS. 5 and 6, the diffuser 10 includes a flat plate-shaped disc portion 32 and a plurality of vanes 34 formed integrally with the disc portion 32.

  The disk part 32 is an example of a shroud forming part according to the present invention. As shown in FIG. 2, the disk portion 32 is fitted in the fitting recess 25 and fastened to the compression portion casing 4 by a plurality of bolts 36. The disk portion 32 is made of a material having higher corrosion resistance than the material of the compression portion casing 4. Specifically, the material of the disk part 32 is stainless steel. The disk part 32 is arranged so as to overlap with the blade 28 of the impeller 8 in the radial direction in a state where it is coupled to the compression part casing 4.

  As shown in FIG. 2, the disk portion 32 has an R-shaped inner circumferential surface 32 a that expands in diameter so as to approach the axis direction perpendicularly toward the casing cover 6 side from the outlet-side tapered surface 22 f of the compression portion casing 4. Have The inner peripheral surface 32 a forms a continuous shroud surface 38 that faces the outer end edge 28 a of the blade 28 together with the inner peripheral surface 22 c of the compression section casing 4. The shroud surface 38 is a smooth curved surface that spreads outward in the radial direction toward the casing cover 6 side. The outer end edge 28 a of the blade 28 has a shape along the shroud surface 38, and a small shroud gap is formed between the shroud surface 38 and the outer end edge 28 a of the blade 28.

  The disk portion 32 has an end surface 32b facing the casing cover 6 side. The end surface 32 b is perpendicular to the axial direction and is disposed with a gap between the end surface 32 b and the casing cover 6. The end surface 32 b is disposed so as to be continuous with the end surface 24 b of the scroll portion 24. A gap 40 between the end surface 32b of the disk portion 32 and the end surface 24b of the scroll portion 24 and the casing cover 6 forms a passage 40 that connects the internal space 22a of the housing portion 22 and the spiral chamber 24a.

  Each vane 34 is a plate made of the same material as the disk portion 32 and is formed integrally with the disk portion 32. Each vane 34 protrudes from the end surface 32b of the disk part 32 to the casing cover 6 side as shown in FIG. As shown in FIG. 5, the plurality of vanes 34 are arranged at intervals in the circumferential direction of the disk portion 32, and are arranged obliquely with respect to the radial direction of the disk portion 32. The vane 34 distributes the compressed gas passing through the passage 40 (see FIG. 2) in the rotation direction of the impeller 8 to reduce the flow velocity.

  As shown in FIGS. 1 and 2, the shim 11 is a thin flat plate member sandwiched between the casing cover 6 and the speed increaser casing 18, and a plurality of sheets having different normal thicknesses are inserted therein. In FIG. 2, for convenience of illustration, a plurality of shims 11 are shown as one rectangle. The adjustment range required for the shim 11 is not large, and the planned value (initial value) of the thickness (the total value of the thicknesses when a plurality of sheets are inserted) is about 1 mm or less. By providing the shim 11, the axial position of these members can be adjusted in a state where the casing cover 6 and the compression portion casing 4 are integrated.

  In the compressor configured as described above, when the gas is compressed, the low speed shaft (not shown) is rotated by the power from the motor (not shown), and the rotational motion of the low speed shaft is the low speed gear 12 (see FIG. 1). ) To the high speed gear 14 and transmitted. The rotational movement of the high speed gear 14 is transmitted from the high speed shaft 16 to the impeller 8, and the impeller 8 rotates integrally with the high speed shaft 16. Thereby, the gas sucked into the internal space 22a of the accommodating portion 22 from the introduction port 22b is compressed by the impeller 8. The compressed gas is diffused in the rotational direction of the impeller 8 by the vanes 34 of the diffuser 10 when flowing into the spiral chamber 24a through the passage 40, and the flow velocity is reduced. As the flow rate decreases, the gas is pressurized and discharged from the compressor through the spiral chamber 24a.

  Next, the method for manufacturing the compressor according to the present embodiment will be described.

  First, the cylindrical raw material of the compression part casing 4 is formed by casting, and only the parts requiring processing accuracy such as the fitting recess 25 and the inner peripheral surface 22c (see FIG. 3) are formed by machining. And the raw material of the disk part 32 of the diffuser 10 which consists of stainless steel is engage | inserted in the fitting recessed part 25, and it fastens to the raw material of the compression part casing 4 with the volt | bolt 36 (refer FIG. 1).

  Thereafter, while the material of the compression section casing 4 and the material of the disk portion 32 are integrally rotated around the axis by a machine tool, the inner peripheral surface 22c of the housing portion 22 and the inner peripheral surface 32a of the disk portion 32 (see FIG. 2). ) At the same time. That is, the inner peripheral surface 22 c of the housing portion 22 and the inner peripheral surface 32 a of the disk portion 32 are co-processed. As a result, there is no step between the end edge portion 22g of the outlet-side tapered surface 22f and the inner peripheral surface 32a of the disc portion 32, and the inner peripheral surface 22c and the disc portion 32 of the accommodating portion 22 form a smoothly continuous curved surface. An inner peripheral surface 32a is formed.

  The compression part casing 4 and the diffuser 10 are formed by the above processes.

  The speed increaser 2 (see FIG. 1) is assembled separately. The impeller 8 is attached to the end of the high-speed shaft 16 and the compression section casing 4 formed as described above is fastened to the speed increaser casing 18 via the casing cover 6 and the shim 11. As described above, the compressor according to the present embodiment is manufactured.

  In the compressor according to this embodiment described above, the inner peripheral surface 32a of the disk portion 32 made of stainless steel having higher corrosion resistance than cast iron or cast steel, which is the material of the compression portion casing 4, forms part of the shroud surface 38. To do. For this reason, in the shroud surface formed by the disk part 32, the expansion of the shroud gap due to corrosion can be prevented. For this reason, the performance fall of a compressor can be controlled.

  In addition, in order to prevent the expansion of the shroud gap due to corrosion, the entire compression portion casing 4 can be formed of stainless steel, but the manufacturing cost is remarkably increased. On the other hand, in this embodiment, since the corrosion resistance of the shroud surface 38 can be improved using the disk portion 32 of the diffuser 10 formed of stainless steel, an increase in manufacturing cost can be suppressed.

  In addition, the shroud gap may be expanded due to distortion of the compression section casing 4, the casing cover 6, and the speed increaser casing 18 due to aging. Although the shroud clearance expanded due to corrosion is difficult to repair, the shroud clearance expanded due to distortion can be repaired by adjusting the thickness of the shim 11 sandwiched between the casing cover 6 and the gearbox casing 18. For this reason, the cause of the expansion of the shroud gap can be easily adjusted in the vicinity of the outlet of the inner space 22a by forming the shroud surface 38 located in the vicinity of the outlet of the inner space 22a with the disk portion 32 having high corrosion resistance. It can be limited to those caused by severe distortion.

  In the present embodiment, the inner peripheral surface 22c and the inner peripheral surface 32a of the disk portion 32 are simultaneously cut out in a state where the material of the disk portion 32 is combined with the raw material of the compression portion casing 4, A smooth shroud surface 38 composed of 22c and 32a can be easily formed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, the material of the diffuser is not necessarily limited to stainless steel. Any material having higher corrosion resistance than the material of the compression section casing can be used as the material of the diffuser. The number of shims 11 may be one.

4 Compression section casing (casing)
8 Impeller (impeller)
10 Diffuser 22a Inner space 22c Inner peripheral surface 28 Blade 28a Outer edge 32 Disc part (shroud forming part)
32a Inner peripheral surface 38 Shroud surface 40 Passage

Claims (5)

A casing,
An impeller provided rotatably in the casing;
Wherein arranged in the casing, and a diffuser for reducing the flow speed of the compressed gas by the impeller,
The impeller has a blade extending toward the inner peripheral surface of the casing,
The diffuser has a shroud forming part that forms part of a shroud surface facing the blade,
The said shroud formation part is a compressor which consists of stainless steel which is a material with higher corrosion resistance than the casting which is the cast iron which is the raw material of the said casing, or cast steel .   The compressor according to claim 1, wherein an inner peripheral surface of the shroud forming part forms the continuous shroud surface together with an inner peripheral surface of the casing. The casing has an internal space for accommodating the impeller,
The compressor according to claim 1, wherein the shroud forming unit forms the shroud surface at an outlet of the internal space where the compressed gas is discharged. A gearbox having a gearbox and a gearbox casing on which the gearwheel is arranged, and a gearbox for increasing the rotational force of the motor and transmitting it to the impeller ;
A casing cover that covers an end of the internal space on the gearbox casing side;
A shim sandwiched between the speed increaser casing and the casing cover;
Equipped with a
The compressor according to claim 3 . A method for manufacturing the compressor according to any one of claims 1 to 4,
A cutting step of simultaneously cutting the inner peripheral surface of the casing and the inner peripheral surface of the shroud forming portion in a state where the shroud forming portion is coupled to the casing;
Compressor manufacturing method.

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