JP2004339999A - Multistage fluid machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce channel loss and enhance efficiency of multistage fluid machinery by appropriately setting a sectional shape of the channel ranging from one impeller to a next impeller. <P>SOLUTION: This multistage fluid machinery comprises: the impeller 13 fixed to a rotation shaft 12; and a guiding blade assembly 20. The guiding blade assembly 20 is provided, at its annular base 21 with, a plurality of guiding blades 22 each having a guiding blade part 22a and a return blade part 22b arranged contiguously to the guiding blade part 22a. A section of an outside wall surface 21e of the base 21 in a direction orthogonal to a flowing direction F of a fluid in a return channel 40 constituted by the pair of guiding blades 22 adjacent to each other and the outside wall surface 21e has a linear shape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multi-stage fluid machine such as a multi-stage pump used as a blower, a compressor, a boiler feed pump or the like.
[0002]
[Prior art]
Conventionally, a multi-stage fluid machine of this type includes a plurality of impellers fixed to a rotating shaft, a guide vane or a diffuser vane for restoring high-speed fluid from one impeller to static pressure, and a fluid with static pressure restoring. And a return blade that rectifies the current to a next-stage impeller (see, for example, Patent Document 1). Further, in order to guide the fluid more smoothly from one impeller to the next impeller, as shown in FIGS. 10 and 11, a portion corresponding to the guide blade and a portion corresponding to the return blade are continuously formed. There is also known a device provided with a guide blade assembly 3 in which a plurality of guide blades 1 having an integral structure are provided on a ring-shaped base 2.
[0003]
[Patent Document 1]
Japanese Patent No. 3299938 (FIG. 1)
[0004]
[Problems to be solved by the invention]
In the conventional multi-stage fluid machine including the guide vanes 1 having the integral structure, a space obtained by rotating the U-shaped flow path cross-sectional shape simply determined by a cross section including the rotation axis (meridian cross section) once around the rotation axis. However, the return flow path from one impeller to the next impeller is formed. Referring also to FIG. 12, the return flow path 5 from one impeller to the next stage impeller includes a pair of guide blades 1 adjacent to each other and a base 2 to which the base end of the guide blade 1 is fixed. It is composed of an outer wall surface 2a and a wall surface 6 arranged on the tip side of the guide blade 1. When the return flow path 5 is determined as described above, the cross-sectional shape of the return flow path 5 does not change smoothly with respect to the flow direction of the fluid indicated by the arrow F in FIGS. More specifically, FIGS. 12A to 12E show the cross-sectional shapes of the return flow path 5 at the positions (1) to (5) in FIGS. 10 and 11, and FIGS. In comparison with positions (1) and (2) shown in (B), at positions (3) to (5) shown in FIGS. 12 (C) to (E), the outer wall surface 2a of the base 2 is bent outward. It is protruding. If the cross-sectional shape of the return flow path 5 in the fluid flow direction F changes partly abruptly as described above, flow path loss occurs, which hinders improvement in efficiency of the multi-stage fluid machine.
[0005]
Therefore, an object of the present invention is to reduce the flow path loss by appropriately setting the cross-sectional shape of the flow path from one impeller to the next stage impeller.
[0006]
[Means for Solving the Problems]
The present invention provides a rotating shaft that is rotationally driven by a drive source, a plurality of impellers that are fixed to the rotating shaft and allow the fluid that has flowed in from the center side to flow out of the outer periphery, and the kinetic energy of the fluid that has flowed out of the impeller is A plurality of guide vanes having a guide vane portion for converting into a plurality of guide vanes and a return vane portion provided continuously with the guide vane portion and guiding fluid to the next stage impeller are provided on the annular base. In a multi-stage fluid machine, comprising a plurality of guide vane assemblies, at least in a direction orthogonal to a flow direction of a fluid in a flow path formed by a pair of guide vanes adjacent to each other and an outer wall surface of the base, A multi-stage fluid machine is provided, wherein a cross section of an outer wall surface of the base is linear.
[0007]
In the multi-stage fluid machine of the present invention, since the outer wall surface of the base of the guide vane assembly has a linear cross-sectional shape in a direction orthogonal to the flow direction of the fluid in the flow path, the cross-sectional shape of the flow path with respect to the flow direction is Changes smoothly. Therefore, the flow path loss is reduced, and the efficiency of the multi-stage fluid machine is improved.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0009]
FIG. 1 shows a ring-section type multi-stage pump according to an embodiment of the present invention. A rotary shaft 12 extending horizontally through a casing 11 of the multi-stage pump is provided. The casing 11 accommodates four impellers 13 and three guide blade assemblies 20 corresponding to the three impellers 13 except for the last stage impeller 13. The impeller 13 is fixed to the rotating shaft 12, and the guide blade assembly 20 is fixed to the casing 11 as described later in detail.
[0010]
The casing 11 includes a suction-side casing 14 to which a suction port 15 is attached, and a discharge-side casing 16 having a discharge port 16a, and three ring-shaped nuts are provided between the suction-side casing 14 and the discharge-side casing. A casing 17 is provided. The suction side casing 14, the discharge side casing 16, and the three Naka casings 17 are fixed to each other by being tightened with stay bolts 31 extending parallel to the rotating shaft 12. In FIG. 1, reference numeral 32 denotes a lagging plate that covers the Naka casing 17.
[0011]
Outside the suction side casing 14 and the discharge side casing 16, packing boxes 34A, 34B accommodating the respective seal mechanisms 33A, 33B are attached. Outside the packing boxes 34A and 34B, bearing brackets 36A and 36B accommodating the slide bearings 35A and 35B for supporting the rotating shaft 12 are arranged. The bearing bracket 36A is attached to the suction side casing 14, and the bearing bracket 36B is attached to the discharge side casing 16. A bearing bracket 36C that accommodates a rolling bearing 37 that supports the rotating shaft 12 is further attached to the bearing bracket 36B on the discharge side casing 16 side.
[0012]
The rotating shaft 12 is rotationally driven by a motor 38 (drive source) schematically shown in FIG. The impeller 13 is fixed to the rotating shaft 12 and rotates together with the rotating shaft 12. The fluid flowing from the inlet 13a located at the radial center of the impeller 13 flows out of the outlet 13b on the outer periphery. 2, the impeller 13 includes a main plate 13d integral with a boss 13c fixed to the rotating shaft 12, a side plate 13e spaced from the main plate 13d, a main plate 13d and a side plate 13e. And a plurality of blades 13f provided between them.
[0013]
Next, the guide blade assembly 20 will be described in detail. 3 to 6, the guide blade assembly 20 includes a disk-shaped base 21 having an insertion hole 21 a in the center thereof through which the rotary shaft 12 is inserted, and the base 21 has an outlet of one impeller 13. A plurality of guide vanes 22 for constituting a return flow passage 40 (see FIGS. 7 and 8) from 13b to the next stage impeller 13 are provided integrally. Specifically, the guide blade 22 and the base 21 are integrally formed by casting, and the base end of each guide blade 22 is fixed to the base 21. In the following description, the front surface 21 b of the base 21 of the guide blade assembly 20 refers to the surface of each guide blade assembly 20 facing the corresponding impeller 13. For example, in the case of the rightmost guide blade assembly 20 in FIG. 1, the front surface 21 b of the base 21 refers to a surface facing the first impeller 13 from the suction port 15. Further, the back surface 21f of the base 21 of the guide blade assembly 20 refers to a surface corresponding to the impeller 13 at the next stage. For example, in the case of the guide blade assembly 20 on the rightmost side in FIG. 1, the back surface 21 f of the base 21 refers to a surface facing the second-stage impeller 13 from the suction port 15.
[0014]
As shown in FIGS. 3 and 4, an edge 21c protrudes in the thickness direction on the front surface 21b of the base 21 of each guide blade assembly 20, and the impeller 13 corresponding to the shallow recess 21d surrounded by the edge 21c. Main plate 13d is disposed.
[0015]
As shown most clearly in FIGS. 3 to 6, each guide blade 22 extends from the edge 21 c of the front surface 21 b of the base 21 to the vicinity of the insertion hole 21 a of the rear surface 21 f of the base 21. The guide vanes 22 are located on the front surface 21b side of the base 21 and convert the kinetic energy of the fluid flowing out of the outlet of the impeller 13 into pressure, and the guide vanes 22a are located on the back surface 21f side of the base 21 to transfer the fluid. A return blade portion 22b for guiding to the next stage impeller 13; Further, the guide blade 22 includes a U-shaped path blade portion 22c extending from the vicinity of the outermost periphery of the front surface 21b of the base 21 to the vicinity of the outermost circle of the back surface 21c of the base 21. The guide blade portion 22a and the return blade portion 22b are connected to a U-shaped road blade portion 22c. In other words, each guide blade 22 has a structure in which a guide blade 22a, a U-shaped path blade 22c, and a return blade 22b are continuously and integrally provided.
[0016]
As shown in FIGS. 2 to 6, each guide blade assembly 20 includes a front wall 23 that connects the tip of the guide blade 22 in the guide blade portion 22a. The front wall 23 is integrally formed with the base 21 and the guide blades 22 by casting. By providing the front wall 23, the guide blades 22 of the guide blade assembly 20 are fixed at the base end to the base 21, while the front end is fixed to the ring-shaped front wall 23. In other words, each guide blade 22 is supported by the both-ends support structure. With the support structure at both ends, the rigidity of each guide blade 22 is improved. Referring to FIG. 2, the inner wall surface 23a of the front wall 23 has a curved shape along the tip of the guide blade 22a. On the other hand, the outer wall surface 23b of the front wall 23 has a cylindrical shape, and the foremost side thereof forms a fitting portion 23d with the Naka casing 17 as described later.
[0017]
Next, an assembly structure of the Naka casing 17 and the guide blade assembly 20 will be described. First, the Naka casing 17 will be described with reference to FIGS. The Naka casing 17 has a ring shape provided with an insertion hole 17a at the center for inserting the boss 13c of the rotating shaft 12 and the impeller 13. A wear ring 18 is mounted on the insertion hole 17a. An accommodation recess 17b for accommodating the corresponding guide blade assembly 20 is provided on the front side of the Naka casing 17. An annular fitting projection 17c is provided on the front side of the Naka casing 17. On the other hand, on the back side of the Naka casing 17, an annular first fitting step 17d provided near the outermost peripheral edge and an inner side (on the rotating shaft 12 side) of the first fitting step 17d are provided. And a second annular fitting step 17e.
[0018]
Referring to FIG. 2, the fitting projection 17c of the Naka casing 17 is fitted into the first fitting step 17d of the preceding Naka casing 17. The front wall 23 of the guide blade assembly 20 disposed in the accommodation recess 17 b of the Naka casing 17 projects from the Naka casing 17. An outer wall surface 23b of a portion of the front wall 23 protruding from the Naka casing 17 is fitted into the second fitting step 17e in the Naka casing 17 in the preceding stage. In other words, a portion of the outer wall surface 23b of the front wall 23 protruding from the Naka casing 17 constitutes a fitting portion 23d to be fitted into the Naka casing 17 at the preceding stage. The guide blade 22 has a three-dimensional shape because the guide blade 22a, the U-shaped road blade 22c, and the return blade 22b are provided continuously. Therefore, in order to fit the guide blades 22 into the Naka casing 17, it is necessary to form a complicated three-dimensional shape on the back side of the Naka casing 17, and it is difficult to assemble. However, in the present embodiment, by providing the front wall 23 with the fitting portion 23d for fitting with the Naka casing 17, the assembling is facilitated and the manufacturability is improved.
[0019]
Next, the return flow path 40 from the outlet 13b of the impeller 13 to the inlet 13a of the next stage impeller 13 will be described. The return flow path 40 includes a pair of guide blades 22 adjacent to each other of the guide blade assembly 20, an outer wall surface 21 e of the base 21 of the guide blade assembly 20, an inner wall surface 23 a of the front wall 23 of the guide blade assembly 20, and a hollow casing 17. It is constituted by the wall surface 17f of the accommodation recess 17b. Specifically, in a region of the return flow path 40 corresponding to the guide blade portion 22a of the guide blade 22, a pair of guide blades 22 adjacent to each other, an outer wall surface 21e of the base 21, and an inner wall surface 23a of the front wall 23 are provided. Thus, the return flow path 40 is configured. In a region of the return flow path 40 corresponding to the U-shaped path blade portion 22c and the return blade portion 22b of the guide blade 22, a pair of guide blades 22 adjacent to each other, an outer wall surface 21e of the base 21, and the accommodation recess 17b The return flow path 40 is constituted by the wall surface 17f of the second member.
[0020]
Referring to FIGS. 7 and 8, the outer wall surface 21 e of the base 21 of the guide blade assembly 20 has a straight cross-sectional shape in a direction orthogonal to the flow direction of the fluid in the return flow path 40 indicated by the arrow F. . This point will be described in comparison with the cross section of the conventional return flow path shown in FIGS. 10 to 12. In the conventional multi-stage fluid machine, in particular, the positions of FIGS. 10 and 11 shown in FIGS. In (3) to (5), since the outer wall surface 2a of the base 2 is curved outward and protrudes, the cross-sectional shape of the return channel 5 in the fluid flow direction F is not smooth. On the other hand, in the present embodiment, as shown in FIGS. 9A to 9E, at any of the positions (1) to (5) in FIGS. The outer wall surface 21e of the base 21 in the direction is straight, and the cross-sectional shape of the return flow path 40 in the flow direction F changes smoothly. Therefore, the flow path loss in the return flow path 40 is reduced, thereby improving the efficiency of the multi-stage pump.
[0021]
As described above, the fluid that has flowed out of the outlet 13b of one impeller 13 flows through the return flow passage 40 to the inlet 13a of the next stage impeller 13. However, the provision of the front wall 23 makes the guide blade assembly Since each guide blade 20 is supported by the both-ends support structure and has high rigidity, even if a fluid instability phenomenon such as a rotating stall occurs in the return passage 40, the guide blade 22 is prevented from being fatigued and broken. be able to.
[0022]
Although the present invention has been described by taking a ring-section type multi-stage pump as an example, the present invention can be applied to various multi-stage fluid machines including a double casing type or barrel type multi-stage pump. Further, the multi-stage fluid machine of the present invention can be used for various applications such as a blower, a compressor, and a boiler feed pump.
[0023]
【The invention's effect】
As is apparent from the above description, in the multi-stage fluid machine of the present invention, the outer wall surface of the base of the guide vane assembly provided with the guide vane provided with the guide vane and the return vane continuously is provided with the guide vane. The cross-sectional shape in a direction orthogonal to the flow direction in the flow path formed by the outer wall surface of the base and the base is linear. Therefore, the cross-sectional shape of the flow path changes smoothly in the flow direction, and the flow path loss is reduced, so that the efficiency of the multi-stage fluid machine can be improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a multi-stage pump according to an embodiment of the present invention.
FIG. 2 is a partially enlarged view of FIG.
FIG. 3 is a perspective view of the guide blade assembly as viewed from the front side.
FIG. 4 is a perspective view of the guide vane assembly as viewed from a slightly front side.
FIG. 5 is a perspective view of the guide blade assembly as viewed from the rear side.
FIG. 6 is a perspective view of the guide blade assembly as viewed from a slightly rear side.
FIG. 7 is a partially enlarged view of the guide vane assembly as viewed from the front side.
FIG. 8 is a partially enlarged view of the guide vane assembly as viewed from the rear side.
FIGS. 9A, 9B, 9C, 9D, and 9E are schematic diagrams showing the cross-sectional shape of the flow channel.
FIG. 10 is a partially enlarged view of the guide blade assembly as viewed from the front side.
FIG. 11 is a partially enlarged view of the guide blade assembly as viewed from the rear side.
FIGS. 12 (A), (B), (C), (D), and (E) are schematic diagrams showing a cross-sectional shape of a flow channel.
[Explanation of symbols]
Reference Signs List 11 Casing 12 Rotary shaft 13 Impeller 13a Inlet 13b Outlet 13c Boss 13d Main plate 13e Side plate 13f Blade 14 Suction side casing 15 Suction port 16 Discharge side casing 16a Discharge port 17 Naka casing 17a Naka casing 17b Housing recess 17c Fitting projection 17d 1 fitting step 17e second fitting step 17f wall 18 wear ring 20 guide blade assembly 21 base 21a insertion hole 21b front 21c back 21c edge 21d recess 21e outer wall 22 guide blade 22a guide blade 22b return blade 22c U-shaped road blade part 23 Front wall 23a Inner wall surface 23b Outer wall surface 23d Fitting part 31 Stay bolt 32 Lagging plate 33A, 33B Seal mechanism 34A, 34B Packing box 35A, 35B Sliding bearing 36A, 36B, 36C Bearing bracket Set 37 Rolling bearing 38 Motor

Claims (1)

A rotating shaft that is rotationally driven by a driving source;
A plurality of impellers fixed to the rotating shaft and configured to allow the fluid flowing in from the center side to flow out from the outer periphery;
A guide blade for converting the kinetic energy of the fluid flowing out of the impeller into pressure, and a return blade provided continuously with the guide blade for guiding the fluid to the next stage impeller. A plurality of guide vanes, wherein the plurality of guide vanes are provided on an annular base, and a plurality of guide vane assemblies.
The cross section of the outer wall surface of the base is linear in a direction orthogonal to the flow direction of the fluid in the flow path formed by at least a pair of the guide blades adjacent to each other and the outer wall surface of the base. A multi-stage fluid machine.

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