JPH025798A - Diffuser of multiple stage centrifugal hydraulic machine - Google Patents

Abstract

PURPOSE:To make manufacture of a guide blade and a diaphragm easy, by forming plural number of guide blades by means of bending a diaphragm which is formed in a plate-shape from a thin plate, from the outer circumference toward the next stage side plate. CONSTITUTION:A guide blade 17 is in a bending shape from the outer circumference 16 of a plate-shape diaphragm 13, and the diaphragm 13 and the guide blade 17 are formed in one body from a thin plate by plastic work. Further, the radius of the guide blade 17 gradually decreases toward rotating direction P of an impeller and forms a diffuser 19 in which the cross section of a flowing path toward a casing cylinder part 11 gradually increases. By connecting the diffuser 19 to a returning flowing path 15 at the end of this guide blade 17, speed head at the outlet of the impeller 2 is converted to pressure head efficiently.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an intermediate diffuser with guide vanes that is interposed between impellers in a multi-stage centrifugal fluid machine that handles gas or liquid. It relates to things formed from plate materials.

[Conventional technology]

FIG. 8 is a half-sectional view of a conventional multi-stage centrifugal blower. In this figure, a plurality of impellers 2 are mounted on a shaft 1 which is rotatably supported and rotationally driven by a prime mover (not shown).
is fixed by a nut 4 via a spacing piece 3 so as to rotate.

A partition plate 53 and a plurality of guide blades 51 are provided between the impellers 2.
A diffuser 5 consisting of a side plate 52 and a side plate 52 is fixedly arranged. The outer periphery of the side plate 52 is deep-drawn to form a cylindrical portion 54, and the cylindrical portions 54 of each diffuser 5 are fitted together to form a casing of the blower. 6
7 is a casing bracket, and 7 is a suction port, but the blower discharge port is not shown.

Generally, the flow at the outlet of each impeller 2 has a circumferential component, so the outer circumference of the guide vane in the next stage forms an appropriate angle with respect to the radial direction, and the inner circumference of this guide vane is approximately radial. The flow towards the impeller inlet of the next stage is optimized. After all, when viewed from the axial direction, the guide vane 51 is formed into an appropriate curve close to an involute curve. As mentioned above, the diffuser 5 is composed of the guide vanes 51, the partition plates 53, and the side plates 52, and these have a plurality of protrusions 55 provided on each guide vane 51 in the parts corresponding to the protrusions 55 of the partition plate 53 and the side plates 52. It is inserted into a provided hole and fixed by a method such as plastic processing such as caulking, thereby forming a portion as the diffuser 5.

[Problems to be Solved by the Invention] In the diffuser 5 made of a metal plate according to the prior art as described above, at least three types of parts 51, 52 and 53 are required for each stage of diffuser, and the protrusion 55
When inserting the guide blade 51 into the hole, it is necessary to precisely match the curved shape of the guide vane 51 and the position of the protrusion 55 with respect to the hole. Moreover, a plurality of guide vanes 51 can be connected to the partition plate 53 at the same time.
Since it is necessary to temporarily assemble it to the side plate 52 and then tighten it, the work is difficult, there is a tendency for defective products to be produced, and there are problems such as the caulking loosening during use and causing problems.

An object of the present invention is to provide a diffuser that is hydrodynamically efficient by easily manufacturing guide vanes and partition plates.

[Means to solve the problem]

This invention is described below.

■) A multi-stage centrifugal fluid machine that communicates an impeller chamber formed between a side plate and a partition plate with a return passage formed between the partition plate and the next stage side plate through a cylindrical part of the casing. In this method, a plurality of guide vanes are formed by bending a partition plate formed into a plate shape from a thin plate from the outer peripheral end toward the next side plate, and the radius of the guide vanes from the starting end to the terminal end in the impeller rotation direction is gradually decreased. a diffuser having a gradually increasing cross section is formed between the guide vane and the casing cylindrical part, at least the vicinity of the starting end of the guide vane is brought into contact with the side plate of the next stage, and the terminal end of the guide vane is in contact with the diffuser. It communicates with the return flow path.

2) In the device described in item 1) above, the outer peripheral end of the partition plate is circular, and the radius of the bent end toward the next side plate of the guide vane gradually decreases.

[Function] In the method described in the above means 1), the guide vanes 17 are bent from the outer peripheral end 16 of the plate-shaped partition plate 13, and the partition plate 13 and the guide vanes 17 are formed from a thin plate by plastic working. are integrally formed. Moreover, the guide vanes 17 form a diffuser 19 whose radius gradually decreases in the impeller rotation direction P and whose cross section of the flow path gradually increases between the guide vanes 17 and the casing cylindrical portion 11, thereby effectively converting the speed head at the outlet of the impeller 2 into a pressure head. Convert to

In this case, as in the first embodiment, the outer peripheral end 1 of the partition plate 13
6 is circular and the radius of the bent end 18 changes, and the third embodiment has the same radius of the outer peripheral end 16 as the radius of the bent end 18 changes. It has the above-mentioned effect.

However, in the one represented by the first embodiment, that is, the one described in the above-mentioned means 2), the diffuser 19
communicates with the same area per unit circumferential length over the entire outer circumference of the impeller chamber 14 (because the outer circumferential end 16 and the casing cylindrical portion 11 are concentric circles). Therefore, the spiral of the flow from the impeller chamber 14 to the diffuser 19 is the same over the entire circumference, and the change in direction of the flow is uniform. This makes the effect of converting the velocity head into a pressure head uniform from the start end to the end end in the diffuser 19, resulting in better efficiency (
Become.

〔Example〕

FIG. 1 is a sectional view of the first embodiment, and FIG. 2 is a cross-sectional view of the first embodiment.
3 is a III-III sectional view in FIG. 1, FIG. 4 is an rV-IV sectional view in FIG. 1, and FIG. 5 is a V-IV sectional view in FIG.
-V sectional view, FIG. 6 is a sectional view of the second embodiment, and FIG. 7 is a sectional view of the third embodiment. Note that FIG. 1 shows a cross section taken along line 1--■ in FIG. 2.

In the first embodiment, an impeller chamber 14 is formed between a side plate 12 that is deep-drawn integrally with the casing cylindrical part 11 and a plate-shaped partition plate 13. The fixed and rotating impeller 2 is housed in the impeller chamber 14. A return passage 15 is formed between the partition plate 13 and the next side plate 12a. Fluid whose pressure increases from the outlet on the outer periphery of the impeller 2 and has a velocity component in the impeller rotation direction P is led to the next stage impeller (not shown) via the return flow path 15.

In order to guide the fluid from the outlet of the impeller 2 to the return channel 15,
The partition plate 13 has a special shape. The outer peripheral end 16 of the plate-shaped partition plate 13 formed of a thin plate of metal or the like is bent to form four guide vanes 17, and the bent end 18 is directed toward the next stage side plate 12a. In this embodiment, the outer peripheral end 16 of the partition plate 13 has a circular shape having the same center as the axis l.

Further, the bent end 18 of the guide vane 17 is bent in the impeller rotation direction P.
From the starting end toward the end, the radius gradually decreases from cross section ■ to cross section ■ in the figure. Therefore, the bending angle α changes. The vicinity of the starting end of the guide vane 17 contacts the side plate 12a of the next stage, and the space surrounded by the guide vane 17, the side plate 12a, and the casing cylindrical part 11 forms a diffuser 19 whose cross section gradually increases in the P direction, and the above-mentioned impeller It communicates with the outer periphery of the chamber 14 over the entire circumference, and the end of the diffuser 19, that is, the end of the guide vane 17, communicates with the aforementioned return flow path 15.

In this type of guide blade 17 is formed by deep drawing from the partition plate 13, and α is changed by pressing and bending from the outer periphery.

As shown in the figure, the bent end 18 near the end of the guide vane 17 may not be brought into contact with the side plate 12a, but the gap may be used to return and assist communication with the flow path. In this way, the radial component (centripetal) of the flow in the return passage 15 increases, and the inflow angle to the next stage impeller approaches the ideal. It is preferable to weld 20 or caulk the bent ends 18 of the guide vanes 17 to the next stage side plate 12a as in the conventional example to facilitate assembly.

Although not shown, α at the starting end may be made negative so that the bent end 18 is inscribed in the casing cylindrical portion 11 to facilitate center positioning. Further, the casing cylindrical portion 11 is made to protrude inward in an annular shape, and the next side plate 12a is attached.
The inscribed portion may be sandwiched between the outer circumferential portion and the outer peripheral portion of the inscribed portion.

FIG. 6 showing the second embodiment corresponds almost to the m--■ cross section of FIG. It can be made to have .

In FIG. 6 showing the third embodiment, the guide vane 17b
Any cross section including the axis is set to α=O, and the radius of the outer peripheral end 16 of the partition plate 13 changes in the same way as the bent end 18.

This shape simplifies the process of forming the guide vanes 17 from the partition plate 13 by deep drawing.

〔Effect of the invention〕

This invention provides a multi-stage centrifugal type in which an impeller chamber formed between a side plate and a partition plate and a return passage formed between the partition plate and the next stage side plate are communicated through a cylindrical part of a casing. In fluid machinery, a plurality of guide vanes are formed by bending a partition plate formed into a plate shape from a thin plate from the outer peripheral edge toward the next side plate, and the radius from the starting end to the ending end of the guiding vane in the impeller rotation direction is A diffuser whose cross section gradually increases is formed between the guide vane and the casing cylindrical portion, at least the vicinity of the starting end of the guide vane is brought into contact with the side plate of the next stage, and the end of the guide vane is brought into contact with the side plate of the next stage. Since the diffuser and the return flow path are communicated with each other, the diffuser formed between the guide vane and the casing cylinder converts the velocity head at the outlet of the impeller into a pressure head, improving the efficiency of the fluid machine. In addition, the guide vanes can be easily formed integrally with the partition plate, which is a component of the impeller chamber, by plastic processing of a thin plate, improving the characteristics of fluid machinery, reducing noise, and making it easier to form parts. This has the effect of simplifying assembly.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the first embodiment, Figure 2 is II of Figure 1.
-II sectional view, FIG. 3 is a tol sectional view in FIG. 1, FIG. 4 is an rV-IV sectional view in FIG. 1, FIG. 5 is a V-V sectional view in FIG. The figure is a sectional view of the second embodiment, FIG. 7 is a sectional view of the third embodiment, and FIG. 8 is a sectional view of a conventional technique. 1... Shaft, 2... Impeller, 5.19... Diffuser, 51.17... Guide vane, 52, 12.12a
・=Side plate, 53. 13... Partition plate, 15... Return channel.

Claims (1)

[Claims] 1) An impeller chamber formed between a side plate and a partition plate is communicated with a return passage formed between the partition plate and the side plate of the next stage through a cylindrical part of the casing. In a multi-stage centrifugal fluid machine, a partition plate formed into a plate shape from a thin plate is bent from the outer peripheral edge toward the side plate of the next stage to form a plurality of guide vanes, and the guide vanes are arranged from the starting end to the ending end in the impeller rotation direction. A diffuser whose cross section gradually increases is formed between the guide vane and the casing cylindrical part by gradually decreasing the radius of A diffuser for a multi-stage centrifugal fluid machine, characterized in that the diffuser and the return flow path communicate with each other at a terminal end of the diffuser. 2) In the diffuser for a multi-stage centrifugal fluid machine according to claim 1, the outer peripheral end of the partition plate is circular;
A diffuser for a multi-stage centrifugal fluid machine, characterized in that the radius of the bent end of the guide vane toward the next stage side plate gradually decreases.