PUMP IMPELLER AND RADIAL PUMP COMPRISING THE IMPELLER

Abstract

The invention relates to a pump impeller for a radial pump with a carrier plate comprising an intake side and a rear side situated opposite the intake side, a blading being provided on the intake side for conveying a medium to be pumped, characterized in that, on the rear side of the carrier plate, at least one flow profile is situated which is configured and formed to reduce at least a difference between a pressure-induced balance of forces on the carrier plate and on a cover plate in the case of a rotation of the pump impeller in a rotational direction (DR).

Claims

1. A pump impeller for a radial pump with a carrier plate comprising: an intake side and a rear side situated opposite the intake side, a blading being provided on the intake side for conveying a medium to be pumped, wherein, on the rear side of the carrier plate, at least one flow profile is situated which is configured and formed to reduce at least a difference between a pressure-induced balance of forces on the carrier plate and on a cover plate in the case of a rotation of the pump impeller in a rotational direction (DR).

2. The pump impeller according to claim 1, wherein the at least one flow profile, as seen in a circumferential direction (UR), is a ramp contour, in particular a short ramp contour, i.e., a ramp ridge, or a long ramp contour, i.e., a circular surface segment ramp.

3. The pump impeller according to claim 1, wherein n ramp contours are distributed over a circumference (U) of the pump impeller, n being ≥2.

4. The pump impeller according to claim 1, wherein in an, as seen in a radial direction (R), internal area of the rear side of the carrier plate, the number (n) of the ramp contours is lower than in an area further outside, which has a higher number (n) of ramp contours, in particular an integer multiple of the number (n), in particular in that six ramp contours are provided in the inner area and twelve ramp contours are provided in the outer area (closer to the annular edge).

5. The pump impeller according to claim 1, wherein the at least one ramp contour is formed raised from a base surface of the rear side counter to the rotational direction (DR).

6. The pump impeller according to claim 1, wherein the at least one ramp contour is flush with respect to the base surface of the rear side counter to the rotational direction (DR) and intervals between two ramp contours are formed recessed with respect to the base surface.

7. The pump impeller according to claim 1, wherein the at least one ramp contour is formed raised with respect to the base surface of the rear side, and at least part of the intervals between two ramp contours is formed recessed with respect to the base surface.

8. The pump impeller according to claim 1, wherein the ramp contour has a cut-off edge which extends in particular radially.

9. The pump impeller according to claim 1, wherein a maximum height (h) of the ramp contour is smaller than a wall thickness (t) of the carrier plate.

10. The pump impeller according to claim 1, wherein a radial extension of the cut-off edge extends from a hub area of the pump impeller to a radially outward circumferential annular edge of the base surface.

11. The pump impeller according to claim 1, wherein in that a ramp rear surface of the at least one ramp contour is a plane.

12. The pump impeller according to claim 9, wherein the ramp rear surface, as seen in the circumferential direction (UR), is formed curved, and the curvature is formed constant along the circumferential direction (UR) or increasing towards the cut-off edge.

13. The pump impeller according to claim 1, wherein the cut-off edge descends perpendicular to the base surface.

14. The pump impeller according to claim 1, wherein the cut-off edge descends perpendicular to the ramp rear surface or, in the case of a curved formation of the ramp rear surface, descends perpendicular to a tangent plane to the ramp rear surface in the area of the cut-off edge.

15. A radial pump comprising a pump impeller according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0041] In the following, embodiments of the invention are described in greater detail by way of example with reference to the drawings, in which:

[0042] FIG. 1 is a perspective view of a rear side of a pump impeller according to embodiments of the invention;

[0043] FIG. 2 is a perspective drawing of a cut-out representation of a rear-side flow profile in the formation of a ramp;

[0044] FIG. 3 schematically shows a comparison of a negative pressure distribution on the rear side of a pump impeller without rear-side contouring (left), with seven short ramp contours (centre), and with six long ramp contours (right);

[0045] FIG. 4 schematically shows part of a radial pump according to embodiments of the invention comprising the impeller, in a longitudinal section.

DETAILED DESCRIPTION

[0046] FIG. 1 is a perspective view towards a rear side 2 of an embodiment of the pump impeller 1 according to embodiments of the invention. Opposite the rear side is an intake side 3 of the pump impeller 1. The rear side 2 is formed by a carrier plate 4. On the intake side 3 of the carrier plate 4 is a blading 5. To the intake side, the blading 5 is followed by a cover plate 6. Flow ducts 7 are formed between the carrier plate 4 and the cover plate 6, and are respectively delimited in a circumferential direction UR by blades of the blading 5. In an axial direction AR, the flow ducts 7 are delimited by the carrier plate 4 and the cover plate 6. An intake opening (not shown) for fluid to be pumped is aligned with the axial direction AR, which in FIG. 1 is coincident with the axis of rotation of the pump impeller 1 on the intake side 3 of the pump impeller 1.

[0047] In FIG. 1, a schematically shown hub area 8 is positioned centrally on the middle of the rear side 2 of the carrier plate 4. The rear side 2 has an annular edge 9 outward in a radial direction R. Between the hub area 8 and the annular edge 9 in the radial direction R, a plurality of flow profiles 10 are situated on the rear side 2 of the pump impeller 1. In the embodiment of FIG. 1, the flow profiles 10 are formed as ramp contours 11.

[0048] In a plan view, a ramp contour 11 has a circle-segment-shaped ramp rear surface 12. The ramp rear surface 12 is situated inclined at an angle α (cf. FIG. 2) to a base surface 13 forming the rear side 2, and has a cut-off edge 14 as seen counter to a rotational direction DR. The cut-off edge 14 is orientated approximately parallel to the axial direction AR, and forms a step 15 of height h (cf. FIG. 2). The step 15 is raised with respect to the base surface 13 by the magnitude of the height h. Following a cut-off edge 14 counter to the rotational direction DR, the ramp rear surface 12 of the following ramp contour 11 joins on seamlessly. In the axial direction AR, in this joining area, the ramp rear surface 12 is approximately flush with the base surface 13 and rises at the angle α.

[0049] In the embodiment of FIG. 1, in total six ramp contours 11, each of the same area size (in a plan view), are situated distributed over the circumference U of the rear side 2. In total, six cut-off edges 14 thus occur. The cut-off edges 14 are arranged proceeding from the hub area 8 radially in a spoke shape, and have an angle β of 60° between them in each case. Naturally, in a modification to FIG. 1, the number of cut-off edges 14 and/or associated ramp contours 11 may be lower or higher than six. A number n=6 has proven particularly expedient.

[0050] In the context of modifications to embodiments of the invention, it is also possible to configure the individual ramp contours 11 differently sized in the circumferential direction UR. Thus, for example, a ramp contour 11 having a larger angle β, for example having the angle β=80°, may be followed by a ramp contour 11 having a smaller angle (for example β=40°), and differently sized ramp contours 11 of this type may follow one another alternately.

[0051] In the selection of the segment size (angle β) of the ramps, it is important to have as uniform a distribution as possible over the circumference U, in such a way that no imbalances occur.

[0052] So as to keep the efficiency reduction due to increased flow resistance at the rear side 2 of the pump impeller 1 within the tightest possible limits, it is advisable to select a height h of the step 15 less than or equal to a thickness t of the carrier plate 4. In the embodiment, by comparison with the thickness t, the height h is about half of the thickness t.

[0053] FIG. 2 shows a ramp contour 11 cut away in an enlarged cut-out. The ramp contour 11 of FIG. 2 is a ramp contour 11 such as was described in connection with FIG. 1. The ramp rear surface 12 is circle-segment-shaped in a plan view, and rises from the level of the base surface 13 linearly at the angle α. The ramp rear surface 12 of this embodiment is thus an inclined plane with respect to the base surface 13.

[0054] Equally, it is of course possible to form the ramp rear surface 12 not as a plane but rather as a curved ramp rear surface 12, which rises, for example in a uniformly curved manner, by the height h from the level of the base surface 13 to the cut-off edge 14. In addition, it is possible for the curvature along the circumferential direction UR as far as the cut-off edge 14 not to be uniform, but rather for a lower curvature initially to be present and for the curvature to increase towards the cut-off edge 14.

[0055] FIG. 3 shows in total three rear sides 2 of pump impellers 1. On the far left of FIG. 3, a pump impeller 1 from the prior art without flow profiles 10 on the rear side 2 is shown. In the embodiment of FIG. 3 (centre), the pump impeller 1 has in total seven ramp ridges 20 uniformly distributed in the circumferential direction UR as flow profiles. The ramp ridges 20 likewise have cut-off edges 14. By contrast with the above-described ramp contours 11 (long ramp contours) of the embodiments of FIGS. 1 and 2, ramp ridges 20 differ from the above-described ramp contours 11 (long ramp contours) in that a cut-off edge 14 of a ramp ridge 20 is initially followed in the rotational direction DR by a circle segment surface, which is positioned on the vertical level in the axial direction AR of the base surface 13 and is not inclined with respect to the base surface 13.

[0056] In a plan view, the ramp ridge 20 is formed rectangular with a width b, within which the ramp rear surface 12 rises from the level of the base surface 13 by the height h. Ramp ridges 20 of this type constitute spoke-shaped local elevations. In particular in the area of the ramp ridges 20, i.e., in particular in the region downstream from the cut-off edges 14 counter to the rotational direction DR, a negative pressure occurs locally when the pump impeller 1 is driven in the rotational direction DR. This is indicated in FIG. 3 (centre) by the darker shading in the area of the radial centre of the ramp ridges 20.

[0057] The embodiment of FIG. 3 (right) corresponds to the above-described embodiment of FIG. 1, 2, and has in total six ramp contours 11, which as described above are circle-segment-shaped in a plan view and rise from a cut-off edge 14, leading in the rotational direction DR, of the ramp contour 11 to the cut-off edge 14, trailing in the rotational direction DR, of the ramp rear surface 12.

[0058] FIG. 3 (right) illustrates that, with this type of rear-side contouring of a pump impeller 1 according to embodiments of the invention, a negative pressure that is overall greater and also higher in magnitude can be achieved by comparison with the embodiment in FIG. 3 (centre) and by comparison with the embodiment in FIG. 3 (left) (prior art). The increased negative pressure formation (in FIG. 3, right) is marked with darker hatching in the vicinity U of the cut-off edges 14.

[0059] In tests, the highest negative pressure values, and thus the highest axial force relief of the corresponding axial bearings of the pump, were brought about with the contouring of FIGS. 1 and 2.

[0060] The pump impeller 1 sits on a drive shaft 101, which can be motor-driven in the rotational direction DR. The radial pump 100 has a pump housing 102, which forms a pump chamber 103. The pump impeller 1 sits in the pump chamber 103. The carrier plate 4 forms, with a rear wall 104 of the pump housing 102, a gap 105 in which fluid to be pumped is present. The flow profiles 10 are situated on the rear side 2 of the carrier plate 4. In FIG. 4, the flow ducts 7 are delimited axially to the left by the cover plate 6. In FIG. 4, the fluid to be pumped flows from left to right, flows through the flow ducts 7, and arrives outside through an outlet duct 106. The flow direction of the fluid to be pumped is indicated by arrows 107.

LIST OF REFERENCE NUMERALS

[0061] 1 Pump impeller

[0062] 2 Rear side

[0063] 3 Intake side

[0064] 4 Carrier plate

[0065] 5 Blading

[0066] 6 Cover plate

[0067] 7 Flow ducts

[0068] 8 Hub area

[0069] 9 Annular edge

[0070] 10 Flow profile

[0071] 11 Ramp contour

[0072] 12 Ramp rear surface

[0073] 13 Base surface

[0074] 14 Cut-off edge

[0075] 15 Step

[0076] 20 Ramp ridge

[0077] 100 Radial pump

[0078] 101 Drive shaft

[0079] 102 Pump housing

[0080] 103 Pump chamber

[0081] 104 Rear wall

[0082] 105 Gap

[0083] 106 Outlet duct

[0084] 107 Arrows

[0085] AR Axial direction

[0086] DR Rotational direction

[0087] R Radial direction

[0088] UR Circumferential direction

[0089] U Circumference

[0090] b Width

[0091] h Height

[0092] t Wall thickness

[0093] n Number

[0094] α Angle

[0095] β Angle