Impeller for wastewater pump

Abstract

An impeller for centrifugal pumps having at least one blade for delivering solids-containing media has, between a leading edge of the blade and a circumferential direction, an angle α, and between a leading edge of the blade and a meridional direction, an angle β. Depending on the dominant speed, the associated angles α, β are less than 90°, preferably less than 70°, in particular less than 50°.

Claims

1. A centrifugal pump, comprising: a pump casing; and an impeller, wherein the impeller includes at least one blade configured to convey solid-containing media, the at least one blade having an angle α between an inlet edge of the at least one blade and a peripheral direction and an angle β between the inlet edge of the at least one blade and a meridional direction, the impeller is a semi-open impeller without a cover over any portion of an inlet side of the impeller, a radially-innermost end of the at least one blade meets an axially-aligned hub portion of the impeller containing a rotation axis of the impeller at a region of the at least one blade axially farthest away from a rear shroud of the impeller, a dominant speed is the greater of a circumferential speed component of the impeller speed in the peripheral direction and an axial speed component of the impeller speed in the meridional direction, if the dominant speed is the circumferential speed, at least the angle α is less than 90°, if the dominant speed is the axial speed at least the angle β is less than 90°, in an inlet region of the impeller at which the solid-containing media enters the impeller, no solid-containing material shearing structure configured to shear solids from the at least one blade is arranged adjacent to the at least one blade, and the casing is axially adjacent to the at least one blade in at least a portion of a region in which the dominant speed is the circumferential speed.

2. The centrifugal pump as claimed in claim 1, wherein the impeller is a radial wheel.

3. The centrifugal pump of claim 1, wherein if the dominant speed is the circumferential speed at least the angle α is less than 45°, and if the dominant speed is the axial speed at least the angle β is less than 45°.

4. The centrifugal pump as claimed in claim 3, wherein the angle β is less than 45° in a radially inner region of the impeller.

5. The centrifugal pump as claimed in claim 4, wherein the angle α is less than or equal to 45° in a radially outer region of the impeller.

6. The centrifugal pump as claimed in claim 5, wherein the radially inner region and the radially outer region are defined by a limit radius R.sub.g of an axial impeller inlet, where R.sub.a×φ=the limit radius R.sub.g when c.sub.m equals u in the throughflow figure φ=c.sub.m/u at the limit radius R.sub.g, with Ra being the outer radius of the blade, u being the peripheral speed of the blade, and φ being between 0.3 and 0.6.

7. The centrifugal pump The impeller as claimed in claim 5, wherein the at least one blade is precisely one blade.

8. The centrifugal pump as claimed in claim 5, wherein the at least one blade is precisely two blades.

9. The centrifugal pump as claimed in claim 3, wherein the angle α is less than or equal to 45° in a radially outer region of the impeller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an axial section through a waste water pump.

(2) FIG. 2 is a view of the intake opening in accordance with an embodiment of the present invention.

(3) FIG. 3 is a perspective partial cross-section of the intake opening region in accordance with an embodiment of the present invention.

(4) FIG. 4 is a section through the intake opening region in accordance with an embodiment of the present invention.

(5) FIG. 5 is a plan view of the impeller in accordance with an embodiment of the present invention.

(6) FIG. 6 is a perspective view of one half of the impeller in accordance with an embodiment of the present invention.

(7) FIG. 7 is a schematic side view of the inlet region of the blade in accordance with an embodiment of the present invention, showing the definition of the angle β.

(8) FIG. 8 is a plan view of an impeller in accordance with an embodiment of the present invention, showing a definition of the angle α.

DETAILED DESCRIPTION OF THE DRAWINGS

(9) FIG. 1 is a cross-section through a waste water pump. The centrifugal pump illustrated in FIG. 1 is a submersible motor-driven pump. The waste water which is displaced with admixtures is introduced through the intake opening 1 into the pump. The impeller 2 is connected in a rotationally secure manner to a shaft 3, which rotates the impeller 2. The impeller 2 is arranged in a pump housing 4 which in the embodiment is configured as a helical housing.

(10) An insert 5, which is configured in the embodiment as a wear wall or wear ring projects into the intake opening 1 of the pump. The shaft 3 is rotated by a drive 6 which is configured in the embodiment as an electric motor. The drive 6 comprises a rotor 7 and a stator 8.

(11) The pump housing 4 is sealed by a housing cover 9. The housing cover 9 is sealed with a sliding ring seal 10 with respect to the shaft 3. The shaft 3 is supported via bearing elements 11.

(12) FIG. 2 is a view of the centrifugal pump toward the intake opening 1. According to the illustration in FIG. 2, the impeller 2 comprises two blades 12. The impeller 2 has at the center thereof a hub 13 and is connected via a fixing means via this hub 13 to the shaft 3.

(13) The fluid leaves the centrifugal pump via a pressure connection piece 14.

(14) FIG. 3 is a perspective partial cross-section of the components which form the intake opening 1. The insert 5 is fixed to the pump housing 4. To this end, a plurality of holes 15 are provided in the insert 5. The insert 5 can be fixed via the holes 15 to the pump housing 4 by way of fixing means.

(15) The impeller 2 rotates in a counter-clockwise direction when looking toward the illustration according to FIG. 3. The impeller 2 is provided with two blades 12 which are fixed to a rear shroud 16. In the embodiments, the two blades 12 and the rear shroud 16 are constructed in one piece. The blades 12 have a curved extent.

(16) The medium which is displaced with solid admixtures flows axially through the intake opening 1 toward the impeller 2 and radially outward away from the impeller 2 so that the medium leaves the centrifugal pump through the pressure connection piece 14.

(17) The blades 12 have a backwardly curved extent. All the blades 12 of the impeller 2 are constructed to be congruent with each other and have the same form. Each blade 12 extends from the hub 13 with a curvature radially outwardly. In the illustration according to FIG. 3, the two blades 12 are arranged to be offset by 180° relative to each other.

(18) FIG. 4 is a cross-section through the intake opening region according to the illustration in FIG. 3. The insert 5 is a fixed component. The impeller 2 a rotating component. The blades 12 extend outward from the hub 13 radially with a backwardly curved extent.

(19) The illustration according to FIG. 5 also shows this again.

(20) FIG. 6 shows one half of the impeller 2 as a perspective side view. The region of the hub 13 is illustrated here purely to show the constructive shape of the impeller of two cylindrical members. During the formation of the impeller 2, this cylindrical formation can be omitted.

(21) An inlet edge 17 is applied to the hub 13 for each blade 12. The inlet edge 17 of each blade 12 extends between the two points A and B.

(22) FIG. 7 shows the region of the inlet edge 17 in a state illustrated in black. The angle β results between the two auxiliary lines 18 and 19. The angle β is less than or equal to 45° according to the invention. In this case, β is an angle between an inlet edge 17 of a blade 12 and a meridional direction. In this case, β indicates the angle in the relative system. In the absolute system, the angle is designated α. In this case, α describes an angle between an inlet edge 17 of a blade 12 and a peripheral direction. Both angles α or β are less than or equal to 45° according to the invention.

(23) FIG. 8 is a plan view of an impeller showing a definition of the angle α. The angle α is measured between the peripheral direction, that is to say, a circular direction, and a tangent at a point on the blade inlet edge in the radius considered. α.sub.i is the angle at the inner radius R.sub.i, α.sub.g is the angle α at the limit radius R.sub.g and α.sub.a is the angle at the outer radius R.sub.a.

(24) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.