Centrifugal pump in particular for waste water or polluted water

Abstract

The invention relates to a centrifugal pump, in particular a waste water submersible pump having an impeller (1), of which the end face facing the pump intake opening is open and only the end face of the impeller facing away from the intake opening (8) is covered by a circular coaxial impeller hub (2), on which the curved vanes (3, 4) are fastened, and in particular molded on, wherein the base plate (7) having the intake opening (8) facing the impeller (1) or at least one segment (7a) of the base plate is mounted so as to be movable against spring pressure (20) in such a way that the distance thereof from the impeller (1) and thus from the impeller vanes (3, 4) changes.

Claims

1. A centrifugal pump comprising: a pump housing having a base plate forming an intake; an impeller whose front face turned toward the intake is open and whose opposite impeller-end rear face turned toward the intake is formed by a circular coaxial support disk carrying curved integral vanes, the base plate having a segment is movable relative to the pump housing; a spring braced between the segment and the pump housing such that a spacing of the segment from the impeller and thus from the impeller vanes is variable; and an adjustment screw limiting movement of the segment relative to the pump housing.

2. The centrifugal pump according to claim 1, wherein the segment is movably adjustable or deformable.

3. The centrifugal pump according to claim 1, wherein the segment is mounted on the pump housing by the adjustment screw.

4. The centrifugal pump according to claim 3, wherein the adjustment screw is screwed into the pump housing, extends through the base plate, and has a head s in a counterbore that opens toward the impeller.

5. The centrifugal pump according to claim 3, wherein the spring is a helical compression spring that surrounds the adjustment screw and that applies a biasing force to the base plate.

6. The centrifugal pump according to claim 1, wherein a spacing between the vanes and the base plate is 0.5 to 2 mm.

7. The centrifugal pump according to claim 1, wherein the base plate is trough-shaped and has a concavely curved side turned inward toward the impeller, and an axial height of the vanes decreases radially outward complementarily to a curvature of the base plate.

8. The centrifugal pump according to claim 1, wherein the intake has an inner wall formed with flow grooves extending parallel to a primary flow direction in the intake.

9. The centrifugal pump according to claim 8, wherein the inner wall of the intake is cylindrical and the flow grooves extend parallel to an axis of the cylinder inner wall.

10. The centrifugal pump according to claim 1, wherein the base plate of the pump housing having the intake over which free edges of the vanes extend a small distance has at least one C-shaped curved groove, the groove extends from the intake and to an outer edge of the base plate, and the groove is curved opposite to a curvature of the vanes.

11. The centrifugal pump according to claim 10, wherein the groove has two side walls of which the side wall that is last traversed by a vane forms an inclined surface that extends from the groove outward.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Several embodiments are shown in perspective and sectional views in the drawings and are described in more detail below.

(2) FIG. 1 is a perspective view of an axial section through a centrifugal pump,

(3) FIG. 2 is a view of the pump impeller,

(4) FIG. 3 is a view of the pump base plate,

(5) FIG. 4 is a section through a groove in the base plate,

(6) FIG. 5 is an axial section through a centrifugal pump with an externally adjustable base plate,

(7) FIG. 6 is an axial section through a centrifugal pump with internally movable mounting of the base plate against spring pressure,

(8) FIG. 7 is a perspective view of an axial section through a centrifugal pump with a movable segment of the base plate, and

(9) FIG. 8 shows a perspective view of the base plate with a movable region/segment.

SPECIFIC DESCRIPTION OF THE INVENTION

(10) The centrifugal pump according to the invention is particularly suitable for pumping sewage and waste water containing solid particles. It is preferably part of a submersible water pump.

(11) The pump impeller 1 is driven by the shaft of an unillustrated electric motor and is in a pumping chamber between an axially centered intake 8 in a base plate 7 and a wall that separates the electric motor from the pumping chamber. The impeller 1, made of plastic or metal, draws the pumped medium in axially through the intake 8 and expels it radially to a helical channel 14 formed by a pump housing 13 surrounding the impeller 1 and emptying at a pump output. The base plate 7 is concave on its side turned axially inward toward the impeller 1, in particular concavely curved, and the height of vanes 3 and 4 of the pump decreases outwardly corresponding to the base-plate curvature.

(12) The impeller 1 is one-sided, i.e. it has a circular support disk (cover plate) 2 on the back turned toward a rim of the housing 13 and has no front cover plate. On the front face turned toward the intake 8, the support disk 2 carries the two vanes 3 and 4 that are curved (in particular C-shaped), and the concave side of each vane 3 and 4 is directed radially inward toward the unillustrated impeller shaft. Instead of two vanes, one, three or more vanes can also be fixed, in particular integrally formed on the support disk 2.

(13) The approximately C-shaped curved vanes 3 and 4 extend from the inside outward to the outer edge of the impeller 1, and the generatrix of the vane extends parallel or at an acute angle to the pump axis and thus to the impeller shaft, so that each vane is at a right or acute angle to a planar rear face 2a of the support disk 2 on front face 2b of the support disk that rises toward the middle of the disk. The free outer edge of each vane 3 and 4 forms an elongated region 12 of increased thickness that extends as a profile along the vane edge in the embodiment according to FIG. 1 where the profile has a triangular, rectangular or polygonal cross-section with an inclined longitudinal surface 6 turned toward the inner face 7c of the base plate 7 and that is angled parallel to the surface 7c. Here, the spacing between the longitudinal surface or chamfer 6 and the surface 7c is preferably 0.5 to 2 mm. Here also, the spacing between the vanes 3 and 4 and the base plate 7 can increase from the leading edge of the vane to the trailing edge of the vane.

(14) In embodiments not shown, the thick region 12 is not formed with a profile with a cross-section that remains uniform across its length, but rather the thick region 12 is either only partially, in particular in sections, profile-shaped or its cross-section increases or decreases in size from one end to the other. In all embodiments, the largest cross-section of the elongated region 12 of increased thickness is always greater than the width and thickness D of the vane 3 and 4. Here, the region 12 of increased thickness projects on both or at least one side of the vane.

(15) An inner end 9a of each vane 3 and 4 shown in FIG. 2 forms the leading edge of the vane 3 of 4 carries an elongated, in particular integrally formed region 9 of increased thickness that runs along the inner vane edge and is parallel to the impeller shaft in the embodiment shown in FIG. 2. At least one of the regions of increased thickness can however also be disposed at an acute angle to the impeller shaft.

(16) In this embodiment, both regions of increased thickness 9 are formed with profiles with a circular cross-section. The profile may however also have differently-shaped cross-sections instead, in particular oval or elliptical. Furthermore, the cross-section can change in shape and/or size along its length, in particular in sections. In all embodiments of the elongated regions of increased thickness 9 and 12, these are preferably of the material of the vane and thus of the same plastic or metal as the vane, and are preferably unitarily formed therewith.

(17) The gap between the base plate 7 and the vanes 3 and 4 is adjustable such that the pump is adaptable to the various admixtures in the sewage or waste water. Either the entire base plate is axially adjustable, or at least the region juxtaposed with the vanes. The adjustment is carried out, for example, by hand by screwthreads, screws 16 or wedge surfaces, in particular with tools, but also by a hydraulic or pneumatic actuator, in particular computer- and/or remote-controlled.

(18) In the embodiment according to FIG. 5, the base plate 7 is fixed to the pump housing 13 by screws 16 at the outer edge of the base plate, so that an adjustment of gap between the base plate 7 and the impeller 1 can be carried out from the outside.

(19) In the embodiment according to FIG. 6, the base plate 7 is inside the pump housing 13, so that it is outwardly covered by the housing wall 13a. Here, the base plate 7 has a central opening 7d that is aligned with the intake 8 of the housing wall.

(20) The inner base plate 7 is supported by at least one, preferably three or four screws 16 seated in the housing wall and surrounding the intake 8. Here, each screw 16 fits in a bore 17 of the base plate 7. The bore 17 has a counterbore 18 that opens toward the impeller and in which the screw head 21 is engaged. Another bore 19 opening toward the base plate also has a threaded region in the housing wall, and a counterbore of the 19 holds a helical compression spring 20 that bears against the bottom face the base plate 7 in order to push the base plate toward the impeller 1. Since there is a gap of several millimeters between the underside of the base plate 7 and the inside of the housing wall, the base plate can move downward (in FIG. 6) out of the way when a large solid particle passes between the base plate and the outer edges of the impeller vanes.

(21) The embodiment according to FIG. 7 differs from that of FIG. 6 in that the inner mounted base plate has a first region 7a movably or unmovably mounted on the pump housing on which a second, in particular segment 7b is movably mounted against spring pressure and/or held movably by elastic deformability of the component. In this embodiment, the head 21 of the screw(s) rests in a counterbore of the second plate-shaped, in particular segment 7b such that at least the second region and the segment 7b can move out of the way away from the impeller 1 against the pressure of the spring 20 and/or deform when large solid particles pass between the impeller vanes and the plate-shaped segment 7b.

(22) The base plate 7 has, as shown in FIG. 3, three in particular C-shaped curved grooves 10 that extend from the suction port 8 to the outer edge of the base plate 7 and are curved opposite to the curvature of the vanes 3 and 4. The grooves 10 assist in conveying the solids radially outwardly, so that a self-cleaning effect occurs. The outward movement is enhanced in that from the two side walls of the grooves 10, those side walls that were last traversed by a vane 3 and 4 form an inclined surface 15 that extends from the groove outward (see FIG. 4). The inclined surface 15 forms an angle a with the base plate 7 of between 110 and 160.

(23) Instead of three grooves, one, two, four or more grooves can also be incorporated into the base plate.

(24) The preferably cylindrical intake 8 has in its inner wall flow grooves 11 that preferably extend parallel to the primary flow direction in the intake, so that solids in the sewage or waste water are led away from the impeller and the risk of clogging is reduced. Here, the flow grooves 11 are distributed at equal angular intervals across the inner wall of the intake. In the embodiment according to FIG. 3, six flow grooves 11 are shown. The number may however also be smaller (3 to 5) or also larger (7 to 12).