JPH04132898A - Diagonal flow impeller - Google Patents

Abstract

PURPOSE:To reduce the occurrence of a trouble owing to contact of the blade of an impeller with other member, such as a casing, during assembly and disassembly in a state to mount an impeller to a rotor by increasing the outside diameter of the core plate of the impeller to a value higher than the maximum outside diameter of the tip part on the outlet side of the impeller. CONSTITUTION:An outside diameter Da of a core plate 1a of an impeller 1 is increased to a value higher than a maximum outside diameter Db of the end part on the outlet side of a blade 1b. As a result, even in the case of a diagonal flow impeller wherein the impellers 1 are mounted in a multistage on a single rotor 2, a gap (g) is ensured between the blade 1b having low rigidity and other member 8, such as a casing, during assembly and disassembly, and contact is decreased. This constitution reduces the occurrence of a trouble, such as deformation, breakage, and the damage of the blade 1b, owing to contact between the blade 1b and the other member.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mixed-flow impeller in which fluid that has flowed in in the axial direction at the impeller inlet is inclined in the axial direction at the single blade outlet and flows out, and in particular, The present invention relates to a mixed flow impeller suitable for reducing troubles such as deformation, breakage, and damage to one blade when assembling or disassembling the impeller to a casing.

[Prior art] As a conventional technology for this type of mixed flow impeller, there is a
Publication No. 4593, “Industrial Machinery (April 1963 Issue No. 2)
9, page 13 of the August 1952 issue) and "Kobe Steel Technical Report (Volume 38, No. 2 (published in 1988), page 61)".

In the prior art described in the above-mentioned Japanese Utility Model Application Publication No. 60-34593, the outer diameter of the outlet end of the blade is formed to be the same as the outer diameter of the core plate.

On the other hand, in the industrial machinery mentioned above and the conventional technology described in the Kobe Steel Technical Report, the tip of the blade on the exit side is
The core plate side is formed to have the same outer diameter as the core plate, and the opposite side of the core plate is formed to have a larger outer diameter than the core plate.

[Problems to be Solved by the Invention] By the way, as in the technique described in the above-mentioned Japanese Utility Model Publication No. 60-34593, the outer diameter of the outlet end of the blade is formed to be the same as the outer diameter of the core plate. Then, the following problem arises.

In other words, when the average pitch between one blade is W and the length of the blade is L, the chord ratio L/W of the exit side tip of the blade on the opposite side of the core plate is the exit side tip of the blade on the core plate side. It becomes smaller than the chord ratio L/W of the section. In this case, the velocity distortion within the impeller increases, and therefore the distortion of the flow at the exit of the impeller also increases, resulting in a decrease in impeller efficiency and differential user efficiency.

Therefore, in the prior art described in the above-mentioned industrial machinery and Kobe Steel technical report, as shown in FIG. It is formed with a downward slope toward the plate 11a side.

In addition, in FIG. 6, 12 is a rotor, 13° and 14 are diaphragms, and 15 is a differential user.

However, as shown in FIG. 6, when the maximum outer diameter of the outlet end of the blade 11b is made larger than the outer diameter of the core plate 11a, the following problem occurs.

That is, when assembling a mixed flow impeller in which the impeller is attached to a rotor to a casing or disassembling it for maintenance, the protruding tips of the blades tend to come into contact with other members such as the casing. The tips of the blades have the lowest rigidity, so if the tips of the blades come into contact with other members, problems such as deformation, breakage, or damage to the blades are likely to occur.

In addition, in the conventional technology, the maximum outer diameter of the tip of the blade on the exit side is
The outer diameter of the blade 11b is equal to or larger than the outer diameter of the core plate, so as shown in FIG. Can not do it. Therefore, there is a problem that stress is concentrated at the root portion of the blade 11b, that is, the acute angle A portion shown in FIG. 7, and fatigue failure is likely to occur.

A first object of the present invention is to reduce troubles caused by contact between the blades of the impeller and other members such as the casing when assembling the impeller to the casing or disassembling the rotor. The object of the present invention is to provide a mixed flow impeller that can perform mixed flow.

A second object of the present invention is to provide a mixed flow impeller that can improve impeller efficiency and diff user efficiency, and can strengthen the strength of the impeller blades.

A third object of the present invention is to provide a mixed flow impeller that can shorten the pitch between the impellers, the span of the rotor, and the distance between the bearings of the rotor.

[Means for Solving the Problems] The first object is to provide an impeller having at least a core plate and a blade, the outer diameter of the core plate being larger than the maximum outer diameter of the outlet side tip of the blade. This is achieved by:

The second object is to form the outlet end of the blade so as to be inclined downwardly from the opposite side of the core plate toward the core plate, and to form a root portion of the outlet end of the blade, This is achieved by connecting to the core plate with an arcuate surface having a larger curvature than the thickness of the root portion.

The third purpose is to increase the inclination angle of the core plate with respect to a plane perpendicular to the axial direction of the rotor and the meridian plane, respectively, from the vicinity of the blade root to the core plate, rather than the inclination angle from the rotor side to the vicinity of the blade root. This is achieved by forming a small inclination angle to the outlet side end.

[Function] In the invention as set forth in claim 1 of the present invention, the outer diameter of the core plate is formed to be larger than the maximum outer diameter of the tip end on the exit side of the blade. As a result, even with mixed flow impellers in which impellers are mounted in multiple stages on a single rotor, contact between the less rigid blades and other components such as the casing is reduced during assembly or disassembly. be able to. Therefore, troubles such as deformation, breakage, and damage of the blade due to contact between the blade and other members can be reduced.

In the invention according to claim 2 of the present invention, the outlet side tip portion of the blade is formed in a downward slope from the side opposite to the core plate toward the core plate side. As a result, the chord ratio L/W on the side of the blade opposite to the core plate can be made closer to the chord ratio L/W on the core plate side of the blade.

Therefore, the velocity distortion within the impeller is reduced, and the distortion of the flow at the outlet of the impeller is also reduced, so that impeller efficiency and differential user efficiency can be improved. Further, in the invention as set forth in claim 2, the root portion at the tip end on the outlet side of the blade is connected to the core plate by an arcuate surface having a larger curvature than the thickness of the root portion. As a result, the cross-sectional area of the root portion of the blade can be increased, and stress concentration on the root portion can be alleviated, thereby making it possible to prevent fatigue failure.

In the invention according to claim 3 of the present invention, the inclination angle of the core plate with respect to a plane perpendicular to the axial direction of the rotor and the calf surface is set closer to the root of the blade than the inclination angle from the rotor side to the vicinity of the root of the blade. The angle of inclination from the center to the outlet end of the core plate is made small. As a result, the axial dimension of the rotor in the differential user can be shortened, the pitch between the impellers can be shortened, the span of the rotor can be shortened, and the distance between the bearings of the rotor can be shortened. Therefore, the rigidity of the rotor itself can be increased, and the support stability of the rotating rotor by the bearing can be increased.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the present invention,
Figure 1 is a cross-sectional view of a portion of the mixed flow impeller taken along the meridian plane, Figure 2 is an enlarged cross-sectional view of a portion of Figure 1, and Figure 3 is a view of the core plate of the impeller and the outlet end of the blade. The enlarged perspective view and FIG. 4 are cross-sectional views taken on a meridian plane in an assembled state of the impeller, and are explanatory views of the effects of the first embodiment.

In the first embodiment shown in these figures, as shown in FIG. 4, impellers 1 are attached to a single rotor 2 in multiple stages in the axial direction thereof.

In this first embodiment, each impeller 1 has blades 1 on a core plate 1a.
b, and is an impeller without side plates.

Further, this impeller 1 is a mixed flow impeller in which the fluid that has flowed in in the axial direction at the impeller inlet is inclined in the axial direction and flows out at the impeller outlet. At the outlet of the impeller 1, as shown in FIG. 1, a differential user 5 is provided between diaphragms 3 and 4 arranged to face each other in the axial direction of the rotor 2.

Furthermore, a seal member 6 having a labyrinth structure is disposed between the diaphragm 4 and the boss portion or spacer of the impeller 1, as shown in FIG. There is.

As shown in FIG. 2, the outer diameter of the core plate 1a of the impeller 1 is larger than the maximum outer diameter Db of the outlet end of one blade 1b.

As shown in FIGS. 2 and 3, the tip of the blade 1b on the outlet side is formed with a downward slope from the opposite side of the core plate 1a toward the core plate la side, and the root portion of the blade 1b is formed with a downward slope toward the core plate la side, as shown in FIGS. It is connected to the plate 1a by a relatively large circular arc surface with a radius R.

As shown in FIG. 2, the core plate 1a is larger than the inclination angle α from the rotor 2 side to the vicinity of the root of the blade 1b with respect to a plane perpendicular to the axial direction and the meridional plane of the rotor 2. The inclination angle α' from the vicinity of the base of the core plate 1b to the outlet side tip of the core plate 1a is formed small.

In the mixed flow impeller of the first embodiment, as shown in FIG. 2, the outer diameter of the core plate 1a of the impeller 1 is larger than the maximum outer diameter Db of the outlet end of the blade 1b. has been done. As a result, as shown in FIG.
Even in the case of a mixed flow impeller in which the blades are mounted in multiple stages, a gap g is ensured between the blades 1b with low rigidity and other members 8 such as the casing to reduce contact during assembly or disassembly. be able to. Therefore, troubles such as deformation, breakage, and damage of the blade 1b due to contact between the blade 1b and other members can be reduced.

In addition, since the exit side tip of one blade 1b is formed with a downward slope from the opposite side of the core plate 1a toward the core plate la side,
The chord ratio L/W of the outlet-side tip of the blade 1b on the opposite side of the core plate 1a can be brought close to the chord ratio L/W of the outlet-side tip of the blade 1b on the side of the core plate la. the result,
Since the velocity distortion within the impeller 1 is reduced and the distortion of the flow at the outlet of the impeller 1 is also reduced, impeller efficiency and differential user efficiency can be increased. In addition, by tilting the outlet side tip of the blade 1b downward toward the core plate 1a, the outer diameter Da of the core plate 1a is made larger than the maximum outer diameter Db of the outlet side tip of the blade 1b. , the cross-sectional area of the root portion of the blade 1b is widened by a circular arc surface with a relatively large radius R, and the concentration of stress on this root portion can be alleviated, making it possible to prevent fatigue failure.

Furthermore, with respect to the planes perpendicular to the axial direction and the meridional plane of the rotor 2, the core plate 1a is tilted from the vicinity of the base of the blade 1b to the base of the blade 1b, rather than the inclination angle α from the rotor 2 side to the vicinity of the base of the blade 1b. Since the inclination angle α' up to the tip of the outlet side of 1a is made small, the axial dimension Q of the rotor 2 in the differential user 5 can be shortened, and as a result, the impeller 1 is arranged in multiple stages. The pitch between the impellers can be reduced, the span of the rotor 2 can be shortened, and the pitch between the impellers can be reduced.
The distance between the bearings can be shortened. Therefore, the rigidity of the rotor 2 itself can be increased, and the stability of the rotor 2 during rotation can be increased.

Next, FIG. 5 shows a second embodiment, and is a sectional view of the main part taken along a meridian plane.

In this second embodiment, an impeller 1 has a core plate 1a and a blade 1.
b, and a side plate 1c.

A seal member 7 having a labyrinth structure is disposed between the diaphragm 3 and the outer peripheral side of the side plate 1c, and this seal member 7 is assembled to the diaphragm 3.

In this second embodiment, the blade 1b is reinforced by a side plate 1c, and the side plate 1c is also sealed by a sealing member 7. The other functions of the configuration 9 are the same as those of the first embodiment.

[Effects of the Invention] According to the invention described in claim 1 of the present invention described above, the outer diameter of the core plate of an impeller having at least a core plate and a blade is set to be smaller than the maximum outer diameter of the outlet side tip of the blade. As a result, even with mixed flow impellers in which impellers are mounted in multiple stages on a single rotor, during assembly and disassembly, etc.
It is possible to reduce the contact between the blades having low rigidity and other members such as the casing, and therefore it is possible to reduce troubles such as deformation, breakage, and damage of the blades due to contact between the blades and other members.

Further, according to the second aspect of the present invention, the outlet side tip portion of the blade is formed to be inclined downwardly from the opposite side of the core plate toward the core plate side, so that the blade has a Since the chord ratio L/W on the opposite side of the plate can be made as close as possible to the chord ratio L/W on the core plate side of the blade, velocity distortion in the impeller is reduced, and distortion in the flow at the exit of the impeller is also reduced. Because it is smaller, it has the effect of improving single impeller efficiency and differential user efficiency.Moreover, since the root part at the tip of the outlet side of the blade is connected to the core plate by a relatively large arcuate surface with a radius R, the blade The cross-sectional area of the root portion can be increased, which has the effect of alleviating the concentration of stress on the root portion and preventing fatigue failure.

Furthermore, according to the third aspect of the present invention, the inclination angle of the core plate with respect to a plane perpendicular to the axial direction of the rotor and the meridional plane, respectively, is set to be smaller than the inclination angle from the rotor side to the vicinity of the root of the blade. , the angle of inclination from near the root of the blade to the outlet end of the core plate is formed small, allowing the axial dimension of the rotor in a differential user to be shortened, the pitch between the impellers to be small, and the span of the rotor to be shortened. Since the distance between the rotor bearings can be shortened, the rigidity of the rotor itself can be increased, and the rotor can be supported with greater stability during rotation by the bearings.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention,
Figure 1 is a cross-sectional view of a portion of the mixed flow impeller taken along the meridian plane, Figure 2 is an enlarged cross-sectional view of a portion of Figure 1, and Figure 3 is a view of the core plate of the impeller and the outlet end of the blade. The enlarged perspective view and FIG. 4 are cross-sectional views taken on the meridian plane in the assembled state of the impeller, and are explanatory views of the effects of the first embodiment, and FIG. 5 shows the second embodiment of the present invention. , is a sectional view of the main part taken along the meridian plane. FIG. 6 shows the prior art, and is a partial cross-sectional view taken along a meridian plane, and FIG. 7 is an explanatory diagram of the prior art, and is a perspective view of the tip end on the outlet side of one impeller. 1... Impeller, 1a... Core plate, ■b... Impeller,
le: side plate, Da: outer diameter of the core plate, Db: maximum outer diameter of the tip of the exit side of the blade, α: inclination angle from the rotor side to the vicinity of the root of the blade in the core plate, α...Inclination angle from near the root of the blade on the core plate to the tip on the outlet side, R...Radius of the circular arc surface at the root of the blade, 2...
Rotor, 3° 4...Diaphragm, 5...Diffusion user, 8...Other members of the mixed flow impeller, g...Gap between the blades of the mixed flow impeller and other members. Agent Patent Attorney Tadashi Akimoto Minora Figure 1--One Wolf Car la--, υ Plate 1b-m-Blade 2--One Rotor 3.4--One Tire Fukum 5--Day 7A diagram

Claims (1)

[Claims] 1. An impeller having at least a core plate and blades,
A mixed flow impeller characterized in that the outer diameter of the core plate is larger than the maximum outer diameter of the outlet end of the blade. 2. The exit side tip portion of the blade is formed to be inclined downward from the side opposite to the core plate toward the core plate side, and
2. The mixed flow impeller according to claim 1, wherein a root portion at an outlet side tip of the blade is connected to the core plate by an arcuate surface having a larger curvature than the thickness of the root portion. 3. The inclination angle of the core plate with respect to a plane perpendicular to the axial direction of the rotor and the meridian plane, respectively, is set from the vicinity of the root of the blade to the outlet side end of the core plate, rather than the inclination angle from the rotor side to the vicinity of the root of the blade. 3. The mixed flow impeller according to claim 1, wherein the mixed flow impeller has a small inclination angle.