US2710580A

US2710580A - Vaned rotor

Info

Publication number: US2710580A
Application number: US706417A
Authority: US
Inventors: Hans T Holzwarth
Original assignee: MW Kellogg Co
Current assignee: MW Kellogg Co
Priority date: 1946-10-29
Filing date: 1946-10-29
Publication date: 1955-06-14
Anticipated expiration: 1972-06-14

Description

June 14, 1955 T, o zw T 2,710,580

VANED ROTOR Filed Oct. 29, 1946 INVENTOR. Hans 7. HbQuzw-t/z.

ATTORNEY 7 2,710,580 Patented June 14, 1955 ice VANED ROTOR Hans T. Holzwarth, Westfield, N. J., assignor to. The M. W. Kellogg Company, New York, N. Y., a come ration of Delaware Application October 29, 1946, Serial No. 706,417

3 Claims. (Cl. 103-115) The present invention relates to vaned rotors, such as centrifugal pump impellers or turbine wheels.

Vaned rotors, such as centrifugal pump impellers, designed for large pressure heads and small capacity, require a narrow passage width in an axial direction at the discharge end of the impeller. of this general type, the narrow passage width between the shroud and the impeller disc at the discharge region in combination with a small discharge angle, makes the casting of such an impeller integrally with the shroud extremely diflicult, if not'impossible. If the casting of such an impeller is possible, machining thereof be comes extremely difiicult.

One object of the present invention is to provide a vaned rotor of the general type referred to, constructed to permit it to be easily and inexpensively manufactured.

Various other objects of the invention will be apparent from the following particular description, and from an inspection of the accompanying drawings, in which:

Fig. l is an axial section of a centrifugal pump embodying the present invention;

Fig. 2 is an axial sectional view of the impeller;

Fig. 3 is an end view of the impeller taken in the direction of the arrows 33 of Fig. 2; and

Fig. 4 is an opposite end view of the impeller taken in the direction of the arrows 44 of Fig. 2.

Referring to the drawings, the vaned rotor unit of the present invention is shown in the form of a centrifugal pump comprising a vaned impeller secured to a shaft 11, and mounted in a casing 12. The casing 12 defines an axial inlet opening or eye 13 at one end and a volute discharge chamber 14 at its outer periphery. The shaft 11 passes through an opening 15 in the other end of the pump casing 12, and is shown sealed at this opening by means of a suitable sealing device 16, as for instance, a nose seal ring.

The impeller 10 comprises two concentric nested sections and 21 separately formed and constituting the holding disc and the vane disc respectively.

Sections

29 and 21 may each be formed by a casting operation, however, if section 20 is highly stressed in use, then it is preferred to form section 20 by a forging or by a machining operation. The holding disc 20 is designed to withstand the centrifugal forces exerted by its own mass, and also part of the centrifugal forces exerted by the mass of the vane disc 21, and since it does not participate in the transmission of torque from the shaft 11 to the vanes, it does not require special keying or splining with respect to said shaft. The holding disc 20 is concavely contoured at its inner face to define in conjunction with the hub 25 of the vane disc 21, one of the continuous confining guide walls of the vane flow passages 23.

The vane disc 21 which has to transmit the whole torque of the shaft 11 to the vanes, comprises the sturdy hub 25 designed for splined connection to the shaft 11, a shroud plate 26 curvedly contoured at its inner face to define the opposite confining guide wall of the vane flow passages 23, and a series of relatively thin walled vanes For a shrouded impeller Ill 27 integral with said hub and said shroud plate, and extending therebetween. The hub 25, which has its inner face concavely curved and in continuity with the inner curved face of the holding disc 21, is set snugly in a recess 28 of the holding disc 20.

At its outer periphery, the shroud plate 26 has a cylindrical ring or flange 29, which fits snugly in an annular groove 30 in the holding disc 20. The hub 25 is similarly provided at its outer periphery with a cylindrical ring or flange 31, extending with a snug fit in an annular groove 32 of the holding disc 20 at the outer periphery of the cavity 28.

The flange or ring 29 is provided with a series of discharge openings 33 extending between the vanes 27, and arranged in axial alignment and in communication with a narrow discharge passage 34 defined between the inner face of the holding disc 20 and the opposed inner face of the casing 12. This discharge passage 34 leads into the discharge volute chamber 14.

The hub 25 is retained on the shaft 11 by means of a head 35 welded or otherwise secured to the end of said shaft, and seated against the corresponding end of said hub.

The vanes 27 extend from the entrance end of the hub 25 to the flange 29, and the outer diameter of said hub is sufficiently smaller than the outer diameter of said vanes to expose and render readily accessible a substantial portion of the rear side of the vane passages 23 radially outwardly beyond said hub, before the two

impeller discs

20 and 21 are put together. The vanes 27 are shown of the usual substantially spiral shape, with their entrance sections almost substantially radial of the axis of the shaft 11, and their discharge sections curved and approaching tangentiality with respect to the flange 29. The width of the vanes 27 in a line perpendicular to the meridian direction decreases progressively from the entrance end thereof to the discharge end where the vane width is small, so that the impeller will afford a large pressure head and a small volume flow.

The casting and machining of the vane disc 21 is possible, since the flow vane passages 23 are exposed and easily accessible for hand fitting or machining operations radially outwardly beyond the hub 25. The entrance end of the disc 21 is of greater radial or axial width compared to the discharge end, and is therefore not so difficult to manipulate or to handle for fitting or machining operations. The almost radial direction of the vanes 27 at their entrance end and the axial shortness of the hub 25, are both helpful for cleaning, finishing and smoothing the walls of the flow passages 23. Since the annular flow passage 34 on the outlet side of the impeller discharge openings 33 is designed with two flat parallel walls perpendicular to the axis of the impeller, it is possible even in cases of extremely narrow passage width in axial direction at the discharge section of the impeller, to machine and hand fit these openings 33 by removing the material from the ring 28 between the vanes 27. The curving of the vanes 27 towards tangentiality with the flange 29 at their discharge ends makes the connection between said vanes and said flange sufiiciently rigid to permit the use of vanes of the usual wall thickness.

No positive connection is shown between the holding disc 20 and the shaft 11 or the vane disc 21. Nevertheless, there is enough frictional binding action between the holding disc 20 and the shaft 11 or the vane disc 21 to cause said holding disc to rotate with said vane. If desired, the flange 29 may be press-fitted into the groove 30, the hub 25 press-fitted into the recess 28 and/ or the flange 31 press-fitted into the groove 32 to assure binding driving action between the two impeller discs 2% and 21.

Although the construction of the present invention is shown as applied to a centrifugal pump impeller, it

must be understood that as far as certain aspects of the invention are concerned, it is also suitable for an expander type of turbine wheel or runner.

As many changes can be made in the above apparatus, and many apparently widely different embodiments of this invention can be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l A rotor for a centrifugal pump or turbine comprising a holding disc having an annular recess on its inner face, and a vane disc separately formed from said holding disc and mounted in axially opposed relationship with respect thereto for rotation therewith, said vane disc comprising a shroud plate with an annular flange extending into said recess with a snug t, and a series of vanes integral with said plate and extending to said holding disc, said fiangc having discharge openings extending therethrough between said vanes.

2. A rotor for a centrifugal pump or turbine comprising a holding disc having an annular recess on its inner face, and a vane disc separately formed from said holding disc and mounted in axially opposed relationship with respect thereto for rotation in unison therewith, said vane disc comprising a shroud plate, a hub, an annular flange projecting from the inner face of said shroud plate into said recess, and a series of substantially spiral vanes integral with said plate and said hub and extending therebetween from the entrance end of said shroud plate to said flange, said flange having discharge openings extending therethrough between said vanes, said vanes progressively decreasing in meridian width from their entrance to their discharge end, said hub having an outer diameter substantially smaller than the outer diameter of said vanes, whereby substantial portions of said vanes extend radially outwardly beyond said hub, the surfaces of said vanes between said plate and said hub being accessible for finishing to close tolerances during manufacturei 3. A rotor for a centrifugal pump or turbine comprising a holding disc having an opening to receive a shaft, an annular groove in its inner face near its outer periphery, and an annular recess in the center of its inner face around said shaft opening, and a vane disc separately formed from said holding disc and mounted in axially opposed relationship with respect thereto for rotation in unison, said vane disc comprising a shroud plate having an annular flange which extends into said groove and contoured on its inner face to define one confining wall of the vaned flow passages, and a hub set into said recess, said holding disc and said hub having their inner faces contoured in continuous relationship to define coniointly the opposite confining wall of said passages, and a series of substantially spiral vanes integral with said plate and said hub and extending therebetween from the entrance end of said shroud plate to said flange, said flange having discharge openings extending therethroug'n between the vanes, said vanes progressively decreasing in meridian width from their entrance end to their discharge end, said hub having an outer diameter substantially smaller than the outer diameter of said vanes, whereby substantial portions of said vanes extend outwardly beyond said hub, the surfaces defining said vaned flow passages being accessible for finishing to close tolerances during manufacture.

References Cited in the file of this patent UNITED STATES PATENTS 2,401,206 Van Rijswijk May 28, 1946 FOREIGN PATENTS 167,061 Switzerland Jan. 3t, 1934 462,853 Germany July 19, 1928 793,823 France Feb. 1, 1936