JPS62291495A - Centrifugal multistage blower - Google Patents

Abstract

PURPOSE:To improve the efficiency of air blowing by providing an annular side plate on a tip of a current guide in the axis direction and providing an annular extending portion rotated in the axis direction while commutating the exhaust gas from the periphery of impellers, adjoining with each other, onto the periphery of the side plate. CONSTITUTION:Plural straightening guide 8 are radially mounted on the outer end face of a casing 25 located between adjoining impellers and on the tip in the axis direction thereof, an annular side 8 is integratedly formed. An annular extending portion 23a which rotates in the axis direction while straightening the gas exhausted radially from the periphery of the adjoining impellers 4 id formed onto the periphery of the side plate 23. Therefore, it is possible to reduce the pressure loss due to the rotation of high pressure air and the occurrence of a vortex.

Description

[Detailed description of the invention] 3. Detailed description of the invention related.

I will explain. In this figure, a plurality of centrifugal impellers 4 are fixed to a rotating shaft 8 that is cantilever-supported via bearings 1 and 2, and each of these impellers 4 is It is surrounded by a separate casing 5, 6.7. The first stage casing 5 is provided with a suction port 5a at the center of its end face, and the second stage and eighth stage casings 6.7 are each provided with a plurality of rectifying guides 8 radially arranged on their outer end faces. Adjacent said casing 5°6.
7 are connected by fitting their outer peripheral ends into each other.

The impeller 4 is pressed against and fixed to the inner ring end surface of the bearing 2 via an annular press plate 10 and spacer tubes 11 and 12 by screwing a presser bolt 9 into the end surface of the rotating shaft 3, and the axial tip of the rectifying guide 8 is fixed. An annular side plate 18 is integrally formed with a gap g between its inner circumference and the outer circumference of the spacer tube 11. The blower has an impeller 4 caused by rotation of a rotating shaft 8.
As a result, air is sucked in through the suction port 5a, pressurized by the first stage impeller 4, and discharged from the outer periphery.The air is then sent toward the center by the adjacent rectifying guide 8. This air is sucked through the center of the second-stage impeller 4 and further pressurized, and this pressurization is repeated until it is finally sent out from the discharge port 14 as high-pressure air.

This structure has the drawback that the high-pressure air suddenly turns 180° near the large diameter portion and the small diameter portion of the rectifying guide 8, resulting in a large pressure loss, resulting in a decrease in air blowing efficiency.

[Purpose of the invention]

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned drawbacks, it is an object of the present invention to provide a centrifugal multi-stage blower that can improve air blowing efficiency.

[Key points of the invention]

In order to achieve the above object, the present invention provides an annular extension part on the outer periphery of the annular side plate of the rectifying guide, which rotates approximately in the axial direction while rectifying the exhaust air from the outer periphery of the adjacent blade. It is something.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, and the same parts as in FIG. 3 are denoted by the same reference numerals. In this figure, a multistage centrifugal impeller 4 fitted onto a rotating shaft 3 is surrounded by a casing 25 of the same shape for each stage, and the first stage casing 25 has an annular suction port 26 at the center of the end face. They are fixed together by welding, etc. The adjacent impeller 4
A plurality of rectifying guides 8 are provided radially on the outer end surface of the casing 25 between them, and an annular side plate 23 is provided at the axial tip of the rectifying guide 8 between its inner periphery and the outer periphery of the spacing tube 11 fitted into the rotating shaft 3. They are integrally formed with a gap g between them. On the outer periphery of the side plate 23, an annular extending part 28a that rotates in the axial direction while rectifying the exhaust gas discharged in the radial direction from the outer periphery of the adjacent impeller 4 is pressed from one plate surface side in a substantially U-shape. The vertical part of the U-shaped extension part 28a is arranged close to the outer periphery of the main plate 4a of the adjacent impeller 4 in the same axial direction.

The casing 25 is formed by bending the inner peripheral part of the end face inward so that its tip is close to the inner periphery of the annular side plate 4b of the adjacent impeller 4, and the outer local part of the end face is also located in the same axial direction as the outer periphery of the side plate 4b. They are drawn by pressing so that they are close to each other. Adjacent casings 25 are coupled by fitting their outer peripheral ends into each other.

According to the embodiment, the high-pressure exhaust gas discharged radially from the outer circumference of the impeller 4 is rotated in the axial direction by the outer circumference of the end face of the casing 25 and the extension portion 28& of the side plate 28 of the rectifying guide 8, thereby creating a substantially uniform cross section. Since the ventilation path 27 is formed, the pressure loss accompanying the rotation of high-pressure air can be reduced and the air blowing efficiency can be improved.

The pressure loss associated with rotation can be reduced by increasing the axial length of the ventilation passage 27, which passes the highest-pressure exhaust immediately after being discharged from the outer circumference of the impeller 4. Since it is concave in the direction, the outer horizontal part of the U-shaped extension part 23a is lengthened, and the ventilation path 27 can be effectively lengthened. In addition, the ventilation passage 27 has a substantially uniform cross section, and the inner periphery of the end surface of the casing 25 is bent inward to reduce the generation of vortices caused by air blowing, which not only improves the air blowing efficiency but also reduces ventilation noise. It is also possible to reduce the noise level. Furthermore, since the multistage casing 25 has the same shape, it can be standardized.

In FIG. 2 showing another embodiment, a multistage centrifugal impeller 34 has a casing 85 of the same shape for each stage.
The annular side plate 33 of the rectifying guide 8 has an annular extending portion 38a formed around the outer periphery in a substantially U-shape.

The impeller 34 is provided with an annular side plate 84b inclined so that the cross section of the discharge part is narrower than the suction part, and the ventilation passage 37 formed by the outer peripheral end of the casing 85 and the extension part 33a is connected to the casing 35. By forming the outer local portion of the end surface and the outer horizontal portion of the U-shaped extension portion 88a to be inclined, the cross section gradually expands in the direction of air flow. According to this embodiment, the ventilation resistance of the ventilation path 37 can be reduced and the ventilation efficiency can be further improved.

〔Effect of the invention〕

According to the present invention, in a centrifugal multi-stage blower, force loss and generation of eddies are reduced, so that it is possible to not only improve air blowing efficiency but also reduce ventilation noise.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a main part of an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a main part of another embodiment of the invention, and FIG. 8 is a longitudinal sectional view of a conventional example. 4.84... Impeller, 8... Rectification guide, 28.8
8... Side plate, 2a&, 88&... Extension part, 25.8
5...Casing. Figure 3

Claims (1)

[Claims] 1) A multistage centrifugal impeller that takes in air from the center and discharges it in the radial direction, a casing that surrounds this impeller in each stage, and a radial impeller provided on the outer end surface of the casing between the adjacent impellers. In the blower equipped with a rectifying guide, an annular side plate is provided at the axial tip of the rectifying guide, and the blower rotates substantially in the axial direction while rectifying exhaust from a single outer circumferential portion of a blade adjacent to the outer circumferential portion of the side plate. A centrifugal multi-stage blower characterized by being provided with an annular extending portion.