Rotary kinetic fluid motors or pumps – With separating means or guard for solid matter in working...
Patent
1983-09-20
1986-06-10
Hershkovitz, Abraham
Rotary kinetic fluid motors or pumps
With separating means or guard for solid matter in working...
415213A, 415219C, 416185, F04D 2942
Patent
active
045940525
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a centrifugal pump for liquids containing solid material, comprising of a multi-vane impeller.
BACKGROUND ART
Pumps of this kind are used e.g. for transport of fibre suspensions and various sludges. Especially when pumping liquids containing longish solid particles, problems are caused by the particals sticking to the impeller vanes, to their leading edges in particular. This can result in clogging of the impeller and other disturbances in the operation of the pump.
DISCLOSURE OF INVENTION
It is an object of the present invention to eliminate the above mentioned disadvantages. This is realised by arranging the centrifugal force and the impact pressure component, which is parallel to the leading edge of the impeller vane and is brought about by the flow in the pump, to force the solid particles stuck to the leading edge towards the outer end of the leading edge. The outer end of the leading edge of the vane is disposed behind a flange provided with cutting edge grooves intended for detaching and shredding the fibres and sticks and thus preventing them from being accumulated and conveyed to the slot between the vane and the housing.
It is a characteristic feature of the centrifugal pump according to the invention that in a bottom projection the leading edge of the impeller vane is curved backwards in relation to the rotating direction of the impeller in such a way, that the inner edge of the vane runs ahead of the vane outer edge; that the angle between the leading edge and the outer edge is obtuse in a meridian and a bottom projection; that the outer end of the leading edge of the vane is positioned behind a shoulder; and that the shoulder and/or the inside wall of the housing is/are provided with a groove/grooves with a cutting edge which cooperates with the outer end of the leading edge of the vane.
The Finnish patent application No. 2169/79 discloses a single-vane centrifugal pump where the angle between the front edge and the outer edge of the vane is sharp in a meridian and a bottom projection, whereby the solid particles sticking to the front edge are conveyed towards the axis. The hub of the impeller forms a shoulderless extension of the front edge; thus the solid material is removed from the opposite side of the vane along the hub with the main flow. If this method was applied in multi-vane impellers the fibrous and stick-like formed particles could not be removed but they would be accumulated in the junction point of the vanes and would finally close the flow passages.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in detail below with reference to the accompanying drawing where
FIG. 1 is a sectional view of an impeller of a centrifugal pump according to the invention in a meridian projection,
FIG. 2 is a sectional view in a bottom projection, and
FIG. 3 is a section along line A--A in FIG. 1.
DETAILED DESCRIPTION OF THE BEST MODE OF CARRYING OUT THE INVENTION
The centrifugal pump presented in the figures is provided with a half-open impeller 1 having three vanes 2, the leading edge of which is indicated by the numeral 3, the inner edge by the numeral 4 and the outer edge by the numeral 5. The angle between the leading edge and the outer edge is indicated in the meridian projection (FIG. 1) by .beta. and in the bottom projection by .rho.. The arrow 6 indicates the rotating direction of the impeller.
The housing of the centrifugal pump constitutes an inlet opening 7 the inside wall 8 of which is provided with a shoulder 9 behind which outer end of the leading edge 10 of the vane is located. Near the outer end of the leading edge of the vane the housing is provided with a sharp-edged groove 11. There is a gap 12 between the outer edge of the vane and the inside wall of the housing.
The angles .beta. and .rho. between the leading edge and the outer edge of the vane are obtuse. In the bottom projection the leading edge of the vane is curved backwards in relation to the rotating direction of the impeller so that the inner edge 4
REFERENCES:
patent: 2202790 (1940-05-01), Forrest
patent: 3644056 (1972-02-01), Wiselius
patent: 3759628 (1973-09-01), Kempf
patent: 4093401 (1978-06-01), Gravelle
A. Ahlstrom Osakeyhtio
Hershkovitz Abraham
Pitko Joseph M.
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