FLOW PUMP

Abstract

A flow pump includes a housing and an impeller. The housing has a suction port, a discharge port, and an inner housing which forms a flow channel. The impeller is arranged in the flow channel to be open on at least one side. The impeller has rotor blades and rotates about a drive axis. The suction port has a front side which faces the impeller. The front side has a circumferential protrusion. Each rotor blade of the impeller has an edge which faces the suction port. Each edge has a height offset over a length of the edge which corresponds to the circumferential protrusion.

Description

CROSS REFERENCE TO PRIOR APPLICATIONS

Priority is claimed to German Patent Application No. DE 10 2023 127 949.1, filed Oct. 12, 2023. The entire disclosure of said application is incorporated by reference herein.

FIELD

The present invention relates to a flow pump, in particular to a centrifugal pump, in particular to a radial pump or a radial centrifugal pump, in the housing of which a fluid to be conveyed is drawn in via a suction port via a motor-driven impeller and conveyed in the desired direction via a flow channel and a discharge port. Such a pump is described, for example, in EP 3 922 855 A1.

BACKGROUND

While pumps with a closed impeller geometry, where the impeller is provided with a cover on both sides of the rotor blades in the axial direction, are efficiency-optimized, impellers that are open on at least one side towards the suction side are used to convey fluids in which solids are entrained in that pumps constructed in this way are less prone to blockages and are easier to clean. A lower degree of efficiency is thereby accepted, which results from the constant low backflow of pumped fluid from the flow channel past the rotor blades into the area of the suction port and the interior of the impeller.

SUMMARY

An aspect of the present invention is to provide a pump with improved pumping characteristics.

In an embodiment, the present invention provides a flow pump which includes a housing and an impeller. The housing comprises at least one suction port, at least one discharge port, and an inner housing which is configured to form a flow channel. The impeller is arranged in the flow channel to be open on at least one side. The impeller comprises rotor blades and is configured to rotate about a drive axis. The at least one suction port comprises a front side which faces the impeller. The front side comprises a circumferential protrusion. Each rotor blade of the impeller comprises an edge which faces the suction port. Each edge has a height offset over a length of the edge which corresponds to the circumferential protrusion.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basis of embodiments and of the drawings in which:

FIG. 1 shows a pump according to the present invention in section;

FIG. 2 shows a corresponding representation of a conventional pump of the prior art for comparison; and

FIG. 3 shows a perspective view of the impeller of the pump shown in FIG. 1.

DETAILED DESCRIPTION

The present invention provides an embodiment in which the edges of the rotor blades on the open side of the impeller, their side facing the suction port, each have a height offset over their length, and the suction port has a circumferential protrusion corresponding to the height offset on its front side facing these impeller edges, whereby the impeller edges and the front side of the suction port engage with each other, so that a fluid return flow, or a gap flow, is diverted so that it does not flow straight in the direction of the drive axis, but is instead diverted directly back into the impeller in the main flow direction. The fluid flow in the pump inlet is therefore not impeded or disturbed, or at least considerably less impeded or disturbed. This allows the flow to be linear from the pump inlet to the blade entry. Despite the double edge formed on the rotor blades due to the height offset in their edges, an open blade wheel geometry is maintained and thus also the advantages of easier cleaning. Thread algae and other coarse contaminants can, for example, still be pumped, which is particularly necessary for the use of the pump according to the present invention as a filter pump, for example, for ponds or for aquariums.

The geometry of the impeller and suction port can, for example, be designed and matched to each other so that the fluid flowing back into the impeller is directed away from the front side of the suction port and back into the impeller. The inflow cross-section of the suction port is thereby not or only marginally affected. There is less turbulence than with conventional pumps with an open impeller geometry.

A design of the pump impeller with double edges of the rotor blades, i.e., exactly one height offset per rotor blade, is generally sufficient to achieve the desired backstreaming deflection. The present invention does not, however, exclude designs with several height offsets at the rotor blade edges and thus a multi-stage flow deflection.

The rotor blades can, for example, be designed so that they have a greater height in their area closer to the outer circumference of the impeller, i.e., towards the outside, than towards the inside, i.e., their area closer to the drive axis. The protrusion of the front side of the suction port is then to be formed on its inside facing the drive axis so that the rotor blades surround this protrusion with their area of greater height on the outside towards the flow channel. The backstreaming or gap flow is thereby directed away from the suction port.

In an embodiment of the present invention, the height offset at the edge of the rotor blade can, for example, be positioned so that the radial distance of the height offset from the drive axis of the pump is greater than or equal to the distance of the protrusion of the suction port from the minimum inside diameter of the suction port in the inlet cross-section, i.e., the length of the blade edge in the area of its reduced height projected onto a radial section through the impeller at the inner leading edge of the rotor blade is less than or equal to the distance of the suction port's protrusion from its minimum diameter. As a result, return flow streaming is unaffected by the internal inflow streaming through the suction port. The influx through the suction port is completely unaffected by the backstreaming or gap flow from the flow channel even if the inside edge of the rotor blade jumps back in relation to the minimum inside diameter of the suction port because the backstreaming or gap flow from the flow channel passes directly into the free area of the impeller.

An optimized flow course and the formation of a laminar flow from the suction port into the pump impeller are also achieved if the protrusion of the front side of the suction port towards the drive axis has an arch-like course, in particular a circular arch-like course, in a section along the drive axis. The wall of the suction port can in particular start in a quarter-circle shape and then widen further towards the suction end of the suction port.

The height offset in the rotor blade edges can, for example, be formed in a step-like or a jump-like manner. A staircase-shaped height offset is particularly advantageous with regard to a simple manufacture. The height offset can, for example, extend perpendicular to the edge areas of the rotor blade facing the suction port, in particular forming two essentially right angles with the two areas of the double edge. A simple design and manufacture is also facilitated if the open edges of the rotor blades facing the suction port are arranged perpendicular to the drive axis, and are in particular straight at least on one side, for example, straight on both sides of the height offset.

Further advantages and details are shown in the drawings.

FIG. 1 shows a radial centrifugal pump in section. The present invention is not, however, limited to radial pumps. The pump has a housing that includes a suction port 1 and a discharge port 2. The direction of flow of the fluid to be pumped is indicated by arrows. Inside the housing is an impeller 3 which can be driven in rotation about a drive axis A via a drive shaft 4. In the embodiment shown here, the impeller 3 is designed as a semi-open impeller, i.e., open on one side, and is closed at the top towards the drive shaft 4, while the impeller 3 is open at the bottom towards the suction port 1. The impeller 3 used here has four rotor blades 13, of which only three can be seen in FIG. 1 due to the sectional view. When the impeller 3 rotates, it draws in the fluid to be pumped through the suction port 1 and conveys the fluid through the rotor blades 13 into a circumferential flow channel 6 which, in the present pump, is designed as a volute casing. The fluid is then conveyed out of the pump from the flow channel 6 through the discharge port 2.

In order to more easily be able to clean the pump, to enable the conveyance of solids transported in the fluid, and to achieve a self-cleaning effect, the pump according to the present invention is designed with an impeller geometry that is open on one side, whereby a constant low backstreaming, see arrow 7, takes place from the flow channel 6 between the rotor blades 13 and a front side 8 of the suction port 1 aligned therewith into an area of the impeller interior.

FIG. 2 shows a corresponding illustration of a conventional pump of the state of the art. As can be seen from the arrows, the gap flow or backstreaming 7 in this pump leads to turbulence in the inflow cross-section of the suction port 1 and thus to a reduction in the effectively usable cross-section.

In the pump according to the present invention in FIG. 1, the rotor blades 13 are each provided with double edges 23, the shape of which is clearly recognizable in FIG. 3. The double edges 23 of the rotor blades 13, which are here designed as circular arc blades, are divided into an inner edge section 23i and an outer edge section 23a, between which there is a height offset h. The rotor blades can, for example, have a greater height Ha in their outer edge section 23a than in the inner edge section 23i directed towards the drive axis A as is shown in FIG. 3. The rotor blade edges 23, their height offset h, and their arrangement correspond to a protrusion 11 of the front side 8 of the suction port 1.

The backstreaming or gap flow 7 between the rotor blade edges 23 and the front side 8 of the suction port 1 is directed upwards along the rotor blades 13 by the double edges 23 of the impeller in FIG. 1 and does not impair the influx of the fluid to be conveyed through the suction port 1. The entire internal cross-section of the suction port 1 is thus effectively usable in the pump according to the present invention. A rounded transition in the cross-section of the suction port 1 to the protrusion 11 also contributes to a laminar flow. It is also favorable if, as shown, the height offset h of the rotor blade edges 23 is set back relative to the minimum inside diameter 9 of the suction port 1 so that the gap flow 7 can adhere to the inside of the rotor blades 13 above the inner edge section 23i and is evenly entrained by the inflowing fluid, as shown by the arrows 12 in FIG. 1.

The embodiment according to the present invention thus provides a pump with significantly improved flow characteristics in a structurally simple design.

The present invention is not limited to embodiments described herein; reference should be had to the appended claims.

LIST OF REFERENCE NUMERALS

• • 1 Suction port
  • 2 Discharge port
  • 3 Impeller
  • 4 Drive shaft
  • 6 Circumferential flow channel
  • 7 Backstreaming flow/Gap flow
  • 8 Front side
  • 9 Minimum inside diameter
  • 11 Protrusion
  • 12 Inflowing fluid
  • 13 Rotor blade
  • 23 Rotor blade edges/Double edges
  • 23 a Outer edge section
  • 23 i Inner edge section
  • A Drive axis
  • h Height offset (between inner edge section 23i and outer edge section 23a)
  • Ha Greater height (in outer edge section 23a)

Claims

1-10. (canceled)

11: A flow pump comprising: a housing comprising at least one suction port, at least one discharge port, and an inner housing which is configured to form a flow channel; andan impeller which is arranged in the flow channel to be open on at least one side, the impeller comprising rotor blades and being configured to rotate about a drive axis,wherein,the at least one suction port comprises a front side which faces the impeller, the front side comprising a circumferential protrusion, andeach rotor blade of the impeller comprises an edge which faces the suction port, each edge having a height offset over a length of the edge which corresponds to the circumferential protrusion.

12: The flow pump as recited in claim 11, wherein the flow pump is a radial pump.

13: The flow pump as recited in claim 11, wherein each edge comprising the height offset and the front side of the suction port comprising the circumferential protrusion together form a slot which is permeable for a fluid to be conveyed, a geometry of the slot being configured so that a portion of the fluid which flows back from the flow channel towards the impeller is directed along the rotor blades away from the front side of the suction port into a free area of the impeller.

14: The flow pump as recited in claim 11, wherein, each of the rotor blades have a height in a region which is closer to an outer circumference of the impeller, and a height in a region which is closer to the drive axis, the height in the region which is closer to the outer circumference of the impeller being greater than the height in the region which is closer to the drive axis, andthe circumferential protrusion of the front side of the suction port is located on an inner side of the suction port which faces the drive axis.

15: The flow pump as recited in claim 11, wherein, the height offset of the edge of each rotor blade is arranged at a radial distance from the drive axis,the suction port comprises a minimum inside diameter,the circumferential protrusion of the suction port is arranged at a distance from the minimum inside diameter, andthe radial distance of the height offset from the drive axis is greater than or equal to the distance of the circumferential protrusion to the minimum inside diameter.

16: The flow pump as recited in claim 11, wherein the circumferential protrusion of the front side of the suction port comprises an arch-like course towards the drive axis in a section along the drive axis.

17: The flow pump as recited in claim 16, wherein the arch-like course is a circular arch-like course.

18: The flow pump as recited in in claim 11, wherein the height offset has an abrupt form.

19: The flow pump as recited in in claim 11, wherein the height offset has a staircase-shaped form.

20: The flow pump as recited in in claim 11, wherein, the edge of each rotor blade further comprises an edge area, andthe height offset of the edge is arranged to extend perpendicular to the edge area.

21: The flow pump as recited in in claim 11, wherein the edge of each rotor blade facing the suction port is arranged perpendicular to the drive axis.

22: The flow pump as recited in in claim 11, wherein the edge of each rotor blade facing the suction port is arranged to be straight on at least one side of the height offset.

23: The flow pump as recited in claim 22, wherein the edge of each rotor blade facing the suction port is arranged to be straight on both sides of the height offset.