CN114278608A - Pump impeller and radial pump comprising said impeller - Google Patents

Abstract

The invention relates to a pump impeller for a radial pump having a carrier plate (4), comprising an inlet side (3) and a rear side (2) located opposite the inlet side (3), a blade row (5) being provided on the inlet side (3) for conveying a medium to be pumped, characterized in that at least one flow contour (10) is located on the rear side (2) of the carrier plate (4), which flow contour is configured and formed to at least reduce the difference between the pressure-induced force balances on the carrier plate and cover plate in the case of a rotation of the pump impeller (1) in the Direction of Rotation (DR).

Description

Pump impeller and radial pump comprising said impeller

Technical Field

The present invention relates to a pump impeller according to the preamble of claim 1 and to a radial pump comprising said impeller.

Background

The impeller for a radial pump from the prior art comprises a carrying plate comprising a blade arrangement towards the intake side, which is provided for conveying the fluid to be pumped. Optionally, this type of pump impeller is covered on the intake side with a cover plate. During operation of this type of impeller, a pressure difference occurs between the inlet side (i.e. on the blade arrangement side as seen from the carrying plate) and the rear side, since the fluid to be pumped is conveyed radially outwards by the rotation of the impeller, in such a way that a suction region occurs radially inwards. Due to the difference between the pressure-induced force balance on the carrier plate and the cover plate, axial forces occur at the impeller. The axial forces must be absorbed or supported by a suitably formed axial bearing system. Therefore, an axial bearing of this type must be dimensioned, shaped and constructed such that it can reliably withstand axial forces over the service life of the radial pump.

Disclosure of Invention

It is an object of the present invention to specify a pump impeller by means of which pressure-induced axial forces acting on the suction opening of the impeller can be reduced without the internal efficiency of the pump impeller or of a radial pump comprising the pump impeller being significantly reduced.

Furthermore, a pump impeller of this type should be able to be produced in a simple manner and without any particular additional complexity compared to the production of prior art pump impellers.

Another object of the invention is to specify a radial pump which generates a low axial force with respect to the pump impeller, which axial force has to be supported/absorbed inside the radial pump.

Another object of the invention is to specify a radial pump which can be produced in an overall cost-effective manner and which is ultimately less complex in terms of the axial bearing system of the drive shaft/pump impeller.

The above object is achieved with a pump impeller having the features of claim 1. Advantageous embodiments are specified in the dependent claims.

The object with respect to a radial pump is achieved by a radial pump having the features of claim 13.

In the context of the following description, the influence of the flow profile on the force balance at the impeller is sometimes referred to for simplicity as "negative pressure" in the rear region of the carrier plate.

According to the invention, a pump impeller for a radial pump having a carrier plate comprises an inlet side on which blades are arranged for conveying a medium to be pumped and a rear side located opposite the inlet side, wherein at least one flow contour is located on the rear side of the carrier plate, which flow contour is configured and formed to at least reduce the difference between the pressure-induced force balances on the carrier plate and cover plate in the case of a rotation of the pump impeller in the direction of rotation DR.

In the pump impeller according to the invention, it is particularly advantageous if the rear-side contour of the impeller carrying plate reduces the axial forces at the impeller which are generated as a result of the difference in the pressure-induced force balance on the carrying plate and the cover plate during operation of the impeller, i.e. during dynamic use in the pump fluid. This occurs by means of a dynamic flow around the at least one flow profile. Due to the rotational movement of the impeller, the fluid to be pumped, which surrounds the flow profile and the shut-off edge, flows through the flow profile, so that the flow behind the shut-off edge is separated. The rise of the flow profile is oriented opposite to the direction of rotation DR of the impeller, which means that when the impeller rotates, the nearby fluid to be pumped migrates along the flow profile, for example towards the cut-off edge. The flow separation at the cut-off edge causes a pressure drop after the flow profile, which reduces the total static pressure distribution in the sealing gap between the pump impeller and the pump casing. This changes the pressure-dependent force balance on the pump impeller and the resulting axial thrust (the resultant axial force of the static pressure balance on the impeller geometry) directed towards the suction area (suction port) is reduced. The flow-through profile also does not generate significant dynamic pressure, for example in comparison with that which occurs in vanes having, for example, a rectangular profile, and this also affects the pressure level. In this case, the influence on the pressure level means that the static pressure distribution in the space behind the wheel, in other words the pressure distribution on the rear side of the carrying floor, is reduced. This results in a lower resultant axial force towards the suction opening.

In summary, therefore, the invention employs a method of specifying a pump impeller and a radial pump comprising said pump impeller, in which the static pressure distribution on the rear side of the carrying plate can be reduced and thus the balance of forces acting on the pump impeller is influenced. In particular, the static pressure distribution at the rear side of the carrier changes or decreases overall over all forces, in such a way that the balance of forces is influenced.

The invention therefore seeks to reduce the resultant axial thrust at the impeller in a targeted manner. This results in a bearing system that is less burdened in the axial direction, making it possible to save costs and to simplify the construction of the choice and design of the axial bearing. Flow profiles, in other words, ramp profile structures, for example, may be used in both mechanical and electrical pumps. Since no undercut contour is applied on the rear side of the carrier plate, production by injection molding can be carried out in a simple manner in a suitable injection molding tool without a slide (slide).

The relatively low dynamic pressure, which is generated, for example, on a flat flow profile, also results in only minimal loss of efficiency in the pump impeller or in a fluid pump comprising the pump impeller.

In a preferred embodiment of the invention, at least one flow profile, as seen in the circumferential direction UR, is a ramp profile, in particular a short ramp profile, i.e. a ramp ridge, or a long ramp profile, i.e. a circular surface section ramp.

The ramp profile has proven to be advantageous in generating a negative pressure; in particular, a short or a long ramp profile of the ramp ridge, i.e. a ramp with a rounded surface section ramp surface, can be envisaged. In the case of short ramp profiles, the non-inclined sub-surface of the rear side of the carrier plate is present between two adjacent ramp ridges in the circumferential direction UR, the effect according to the invention already being evident, but taking place in a locally concentrated manner in the region of the ramp rear surfaces of the ramp ridges, which are relatively short in the circumferential direction UR.

If the flow profile is formed as a long ramp profile, a single inclined ramp rear surface is provided between the two cut-off edges of adjacent ramps and is a circular surface section. In other words, in the case of a long ramp profile, the surface between the two cut-off edges is completely inclined with respect to the plane of the rear side of the carrier plate, whereas in contrast a short ramp has between the two cut-off edges an inclined ramp rear surface and a non-inclined sub-surface of the rear side of the carrier plate.

In the case of the long slope structure, the negative pressure distribution area on the rear side of the pump impeller is larger, and the magnitude of the total negative pressure is also larger.

In a further preferred embodiment of the invention, n ramp profiles are distributed over the circumference U of the pump impeller, n being preferably ≧ 2, particularly preferably n ≧ 4, more preferably n ≧ 6.

As the number of ramp profiles on the rear side of the pump impeller increases, as a basic principle, a reduced pressure difference and a more uniform pressure distribution can be achieved on the rear side of the pump impeller. In order to meet the acoustic requirements to a certain extent, it has proven advantageous to select an integer multiple of the number of pump impeller blades for the number of ramp profiles on the rear side of the pump impeller.

In a further embodiment of the pump impeller according to the invention, the at least one ramp profile is formed to project from the base surface of the rear side in a direction opposite to the direction of rotation DR.

Alternatively, it can be provided that at least one ramp contour (cut-off edge) is flush with respect to the base surface of the rear side and the spacing between two ramp contours (cut-off edges) is formed so as to be concave with respect to the base surface.

In addition to the above-described convex ramp profile and/or a sunken stop edge having a ramp profile flush with the annular edge, it is of course also possible to form a ramp profile which is only partially sunken in such a way that there is a stop edge which is convex relative to the substrate surface and at least one subregion between two adjacent ramp profiles is sunken relative to the substrate surface.

In a further embodiment of the pump impeller according to the invention, at least one ramp profile is formed convex with respect to the base surface of the rear side and at least part of the spacing between two ramp profiles is formed concave with respect to the base surface.

In a further embodiment of the pump impeller, the ramp profile has a stop edge which extends in particular radially.

A particularly high negative pressure development can be observed in the case of a continuous radial extension of the stop edge, in particular in the case of a continuous radial extension in a straight line in the manner of a spoke.

In a further embodiment of the pump impeller according to the invention, the maximum height h of the ramp profile is smaller than the wall thickness t of the carrier disc.

According to the invention, it has been recognized that even a relatively small ramp height h, possibly smaller than the wall thickness of the carrier disc, is sufficient to achieve a good compromise between the achievable underpressure and the acceptable loss of efficiency.

In another embodiment of the invention, the radial extension of the cut-off edge extends from the hub region of the pump impeller to the radially outwardly facing circumferential annular edge of the base surface.

The radial extension of the stop edge advantageously does not extend to the outermost circumferential edge of the carrying plate of the pump impeller in order to avoid any additional flow stop or vortex flow there, wherein the flow occurs at the end of the opposite pumping vane arrangement, which may undesirably reduce the efficiency. An annular ring is thus left on the rear side of the carrier plate of the pump impeller and is at a distance from the circumferential edge of the carrier plate.

In another preferred embodiment, the sloped rear surface of at least one of the sloped profiles is planar.

The sloping rear surface in the form of a plane constitutes a particularly simple three-dimensional shape and can be implemented in particular in a simple manner in a production tool.

In another specific embodiment, the sloped rear surface is formed curved as seen in the circumferential direction UR, and the curvature is formed constant along the circumferential direction UR or increasing toward the cutoff edge.

Since the rear surface of the ramp is curved, the positioning of the negative pressure focus of each ramp can be influenced in a targeted manner.

In a further preferred embodiment of the invention, the cut-off edge is lowered perpendicularly to the substrate surface.

In a further embodiment, the cut-off edge descends perpendicularly to the ramp rear surface, or in the case of a ramp rear surface formed curved, in the region of the cut-off edge a tangent plane perpendicular to the ramp rear surface.

The lowering of the blocking edge perpendicularly to the base surface, i.e. perpendicularly to the plane of the rear side of the carrier plate or perpendicularly to the plane/tangent of the rear surface of the ramp, ensures, in particular in the absence of undercuts, an arrangement without undercuts, which is convenient to implement in the tool.

In a second aspect of the invention, a radial pump comprises a pump impeller according to one of the preceding embodiments.

For a radial pump according to the invention, the aforementioned advantages can be expected if a pump impeller according to the invention is used.

Drawings

In the following, the invention is described in more detail by way of example with reference to the drawings, in which:

FIG. 1 is a perspective view of the back side of a pump impeller according to the present invention;

FIG. 2 is a perspective view of a cutaway illustration of the rear flow profile as the ramp is formed;

FIG. 3 schematically shows a comparison of the negative pressure distribution on the back side of the pump impeller without the back side profile (left), with seven short ramp profiles (center), and with six long ramp profiles (right);

fig. 4 schematically shows part of a radial pump according to the invention comprising an impeller in longitudinal section.

Detailed Description

Fig. 1 is a perspective view towards the rear side 2 of an embodiment of a pump impeller 1 according to the invention. The inlet side 3 of the pump impeller 1 is opposite the rear side. The rear side 2 is formed by a carrier plate 4. The blade arrangement 5 is on the entry side 3 of the carrier plate 4. On the inlet side, the blade row 5 is followed by a cover plate 6. The flow ducts 7 are formed between the carrier plate 4 and the cover plate 6 and are each delimited in the circumferential direction UR by the blades of the blade row 5. In the axial direction AR, the flow tube 7 is delimited by the carrier plate 4 and the cover plate 6. The inlet opening (not shown) for the fluid to be pumped is aligned with an axial direction AR which in fig. 1 coincides with the axis of rotation of the pump impeller 1 on the inlet side 3 of the pump impeller 1.

In fig. 1, a schematically illustrated hub region 8 is positioned in the middle of the rear side 2 of the carrier plate 4. The rear side 2 has an annular edge 9 facing outwards in the radial direction R. Between the hub region 8 and the annular edge 9, in the radial direction R, a plurality of flow profiles 10 are positioned on the rear side 2 of the pump impeller 1. In the embodiment of fig. 1, the flow profile 10 is formed as a ramp profile 11.

The ramp profile 11 has a ramp rear surface 12 in plan view in the form of a circular segment. The ramp rear surface 12 is positioned inclined at an angle α (see fig. 2) with respect to a base surface 13 forming the rear side 2 and has a cut-off edge 14, as seen in a direction opposite to the direction of rotation DR. The cut-off edge 14 is oriented substantially parallel to the axial direction AR and forms a step 15 (see fig. 2) having a height h. The step 15 is raised with respect to the base surface 13 by an amount of height h. Following the cut-off edge 14 in the direction opposite to the direction of rotation DR, the ramp rear surface 12 of the following ramp profile 11 seamlessly engages. In the axial direction AR, in this junction region, the ramped rear surface 12 is substantially flush with the base surface 13 and rises at an angle α.

In the embodiment of fig. 1, a total of six ramp profiles 11, each having the same area size (in plan view), are positioned distributed over the circumference U of the rear side 2. Thus, a total of six cut-off edges 14 occur. The cut-off edges 14 are arranged to run radially from the hub region 8 in the shape of a spoke and have an angle β of 60 ° between them in each case. Of course, in a modification to fig. 1, the number of cut-off edges 14 and/or associated ramp profiles 11 may be lower or higher than six. The number n of 6 has proven to be particularly advantageous.

In the context of a modification of the invention, it is also possible to arrange individual ramp profiles 11 of different sizes in the circumferential direction UR. Thus, for example, a ramp profile 11 with a larger angle β, for example with an angle β of 80 °, may be followed by a ramp profile 11 with a smaller angle (for example β of 40 °), and ramp profiles 11 of different sizes of this type may follow one another alternately.

When selecting the segment size (angle β) of the ramp, it is important to have as uniform a distribution over the circumference U as possible, so that no imbalance occurs.

In order to keep the efficiency reduction due to the increased flow resistance at the rear side 2 of the pump impeller 1 within the strictest possible limits, it is advisable to select the height h of the step 15 to be less than or equal to the thickness t of the carrying plate 4. In an embodiment, the height h is about half the thickness t compared to the thickness t.

Fig. 2 shows the ramp profile 11 in an enlarged sectional view. The ramp profile 11 of fig. 2 is, for example, the ramp profile 11 described in connection with fig. 1. The ramp rear surface 12 is circular segment-shaped in plan view and rises linearly at an angle a from the level of the base surface 13. Thus, the sloped rear surface 12 of this embodiment is a plane that is inclined relative to the base surface 13.

Likewise, the ramp rear surface 12 may of course not be formed as a plane, but as a curved ramp rear surface 12 which rises in a uniformly curved manner, for example, by a height h from the level of the base surface 13 to the cut-off edge 14. Furthermore, the curvature along the circumferential direction UR up to the cut-off edge 14 may not be uniform, but there is initially a lower curvature and the curvature increases towards the cut-off edge 14.

Fig. 3 shows a total of three rear sides 2 of the pump impeller 1. On the leftmost side of fig. 3, a pump impeller 1 from the prior art is shown, which has no flow profile 10 on the rear side 2. In the embodiment of fig. 3 (in), the pump impeller 1 has a total of seven ramp ridges 20 distributed uniformly in the circumferential direction UR as flow profiles. The ramp ridge 20 likewise has a cut-off edge 14. Compared to the above-described ramp profile 11 (long ramp profile) of the embodiment of fig. 1 and 2, the ramp ridge 20 differs from the above-described ramp profile 11 (long ramp profile) in that the cut-off edge 14 of the ramp ridge 20 initially follows, in the direction of rotation DR, a rounded segment surface which is positioned on a vertical level in the axial direction AR of the base surface 13 and is not inclined with respect to the base surface 13.

The slope ridge 20, in which the slope rear surface 12 rises by a height h from the level of the base surface 13, is formed in a rectangular shape having a width b in plan view. This type of ramp ridge 20 constitutes a spoke-shaped local ridge. In particular in the region of the ramp ridge 20, i.e. in particular in the region downstream of the cut-off edge 14 in the direction opposite to the direction of rotation DR, a negative pressure occurs locally when the pump impeller 1 is driven in the direction of rotation DR. This is indicated in fig. 3 (in) by the darker shading in the radially central region of the ramp ridge 20.

The embodiment of fig. 3 (right) corresponds to the above-described embodiment of fig. 1, 2 and has a total of six ramp profiles 11 which, as described above, are circular segment-shaped in plan view and rise from a leading cut-off edge 14 of the ramp profile 11 in the direction of rotation DR to a trailing cut-off edge 14 of the ramp rear surface 12 in the direction of rotation DR.

Fig. 3 (right) shows that with a rear-side contour of this type of the pump impeller 1 according to the invention, a negative pressure which is overall greater and also higher in magnitude can be achieved compared to the embodiment in fig. 3 (middle) and compared to the embodiment in fig. 3 (left) (prior art). The increased negative pressure build-up (in fig. 3, right) is marked with darker hatching near the U of the cut-off edge 14.

In the tests, the highest negative pressure value and therefore the highest axial force release of the corresponding axial bearing of the pump was achieved by means of the contour lines of fig. 1 and 2.

The pump impeller 1 is located on a drive shaft 101 which can be driven by a motor in the direction of rotation DR. The radial pump 100 has a pump housing 102 that forms a pump chamber 103. The pump impeller 1 is located in the pump chamber 103. The carrier plate 4 forms a gap 105 with the rear wall 104 of the pump housing 102, in which gap the fluid to be pumped is present. The flow profile 10 is positioned on the rear side 2 of the carrier plate 4. In fig. 4, the flow tube 7 is delimited axially to the left by the cover plate 6. In fig. 4, the fluid to be pumped flows from left to right, through the flow tube 7 and to the outside through the outlet conduit 106. The flow direction of the fluid to be pumped is indicated by arrow 107.

List of reference numerals

1 impeller of pump

2 rear side

3 side of entry

4 bearing plate

5 arrangement of blades

6 cover plate

7 flow tube

8 hub region

9 annular edge

10 flow profile

11 ramp profile

12 slope rear surface

13 surface of the substrate

14 cut-off edge

15 step shape

20 slope ridge

100 radial pump

101 drive shaft

102 pump casing

103 pump chamber

104 rear wall

105 gap

106 outlet pipe

107 arrow

Axial direction of AR

Direction of rotation of DR

R radial direction

UR circumferential direction

U circumference

b width of

h height

t wall thickness

n number of

Angle alpha

Angle beta.

Claims (15)

1. A pump impeller with a carrying plate (4) for a radial pump, which pump impeller comprises an inlet side (3) and a rear side (2) located opposite the inlet side (3), an arrangement (5) of blades being provided on the inlet side (3) for conveying a medium to be pumped, characterized in that at least one flow contour (10) is located on the rear side (2) of the carrying plate (4), which flow contour is configured and formed to at least reduce the difference between the pressure-induced force balances on the carrying plate and cover plate in the case of a rotation of the pump impeller (1) in the Direction of Rotation (DR).

2. Pump impeller according to claim 1, characterized in that the at least one flow contour (10), as seen in the circumferential direction (UR), is a ramp contour (11), in particular a short ramp contour, i.e. a ramp ridge (20), or a long ramp contour, i.e. a circular surface section ramp.

3. Pump impeller according to claim 1 or 2, characterized in that n ramp profiles (11) are distributed over the circumference (U) of the pump impeller (1), n preferably being ≧ 2, particularly preferably n ≧ 4, more preferably n ≧ 6.

4. Pump impeller according to one of the preceding claims, characterized in that, as seen in the radial direction (R), in an inner region of the rear side (2) of the carrying plate (4), the number (n) of the ramp profiles (11) is lower than in a more outer region having a higher number (n) of ramp profiles (11), in particular an integer multiple of the number (n), characterized in that, in particular, six ramp profiles (11) are provided in the inner region and twelve ramp profiles (11) are provided in the outer region (closer to the annular edge).

5. Pump impeller according to one of the preceding claims, characterized in that the at least one ramp profile (11) is formed to project from a base surface (13) of the rear side (2) in a direction opposite to the Direction of Rotation (DR).

6. Pump impeller according to one of the preceding claims, characterized in that the at least one ramp profile (11) is flush with respect to the base surface (13) of the rear side (2) in a direction opposite to the Direction of Rotation (DR), and the spacing between two ramp profiles (11) is formed so as to be concave with respect to the base surface (13).

7. Pump impeller according to one of the preceding claims, characterized in that the at least one ramp profile (11) is formed convex relative to the base surface (13) of the back side (2) and at least part of the spacing between two ramp profiles (11) is formed concave relative to the base surface (13).

8. Pump impeller according to one of the preceding claims, characterized in that the ramp profile (11) has a cut-off edge (14) which extends in particular radially.

9. Pump impeller according to one of the preceding claims, characterized in that the maximum height (h) of the ramp profile (11) is smaller than the wall thickness (t) of the carrier plate (4).

10. Pump impeller according to one of the preceding claims, characterized in that the radial extension of the cut-off edge (14) extends from the hub region (8) of the pump impeller (1) to the radially outwardly facing circumferential annular edge (9) of the base surface (13).

11. Pump impeller according to one of the preceding claims, characterized in that the ramp rear surface (12) of the at least one ramp profile (11) is plane.

12. Pump impeller according to claim 9, characterized in that the ramp rear surface (12) is formed curved as seen in the circumferential direction (UR) and the curvature is formed constant in the circumferential direction (UR) or increasing towards the cut-off edge (14).

13. Pump impeller according to one of the preceding claims, characterized in that the cut-off edge (14) falls perpendicularly to the base surface (13).

14. Pump impeller according to one of the preceding claims, characterized in that the cut-off edge (14) descends perpendicularly to the ramp rear surface (12) or, in the case of a curved ramp rear surface (12), perpendicularly to the tangent plane of the ramp rear surface (12) in the region of the cut-off edge (14).

15. Radial pump comprising a pump impeller (1) according to one or more of claims 1 to 14.

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