PUMP IMPELLER, HOUSING ELEMENT AND PUMP HEREBY

Description

[0001] The invention relates to a pump impeller according to the preamble of claim 1. Furthermore, the invention relates to a pump according to claim 5 with such a pump impeller.

[0002] Main features of the invention are set out in the characterizing part of claim 1 and claim 5. Embodiments are the subject of claims 2 to 4 and 6 to 13.

[0003] The invention particularly relates to components of vortex pumps, commonly referred to as vortex pumps. Vortex pumps are frequently used in wastewater pumping. Wastewater is characterized by the fact that its exact composition is often unknown. Wastewater frequently contains a high proportion of solids such as long-fibered materials, coarse components such as stones, or chemically aggressive substances. Vortex pumps offer reliable and robust pumping operation, although their efficiency is often somewhat reduced compared to other pump hydraulics.

[0004] WO 2017 / 001340 A1 discloses a pump impeller with two opposing blade groups. The blades have an inhomogeneous material thickness. DE 35 20 263 A1 describes a pump impeller with blades with a blade cover. The pump impellers each have a single blade type.

[0005] WO 2016 / 165795 A1 describes a pump impeller with two different types of blades arranged alternately on an impeller surface. The blades of the first type project beyond the blades of the second type in the axial direction, with a blade edge oriented forward in the direction of rotation. The blades of the second type each consist of a base body that extends perpendicularly from an impeller surface.

[0006] US 2021 / 0003134 A1 discloses a pump impeller with an impeller surface on which blades of a single type are arranged. These blades have a base body that extends essentially perpendicularly from the impeller surface. A blade cover is arranged on the base body and is aligned parallel to the impeller surface.

[0007] The invention is based on the task of increasing the efficiency of a pump, in particular a vortex pump, while maintaining the most constant power consumption possible, thereby optimizing flow control and thus resource efficiency. The solution should enable reliable, long-term operation and be cost-effective.

[0008] An inventive aspect relates to a pump impeller having an impeller surface on which blades are arranged, wherein at least one of the blades is a blade of the first type, provided that at least one of the blades is a blade of the second type, wherein the blade geometry of the blade of the first type differs from the blade geometry of the blade of the second type.

[0009] This achieves a functional separation between the suction of the fluid into the space between the blades and its retention there and its radial outward acceleration along the blades. The different blade geometries can be coordinated to optimize the flow of a pumped fluid through the impeller by avoiding turbulence. Such impellers thus achieve a greater discharge head than impellers that only have blades of one type with a uniform geometry. The power consumption of the impeller according to the invention is comparable to impellers known from the prior art, and thus the efficiency is increased.

[0010] In this pump impeller, the blade geometry of the first-type blade features a blade edge that is inclined forward in the direction of rotation. This contributes significantly to pumping fluid into the space between the blades.

[0011] The pump impeller preferably has a (preferred) direction of rotation (hereinafter simply referred to as the direction of rotation, even if the impeller could theoretically also be driven in reverse) and / or an imaginary axis of rotation around which the pump impeller is intended to rotate during operation. The imaginary axis of rotation (hereinafter sometimes simply referred to as the axis of rotation) runs, for example, through an impeller hub in the impeller surface, which serves for attachment to a drive shaft. The impeller hub can, for example, be a shaft receptacle and can in particular be designed as a bore in the impeller surface (e.g. with a keyway) or a shaft journal (e.g. with a keyway and / or e.g. cylindrical or conical). The axis of rotation is aligned parallel and / or coaxially to the drive shaft and / or the bore. It runs transversely, preferably orthogonally, to the impeller surface.

[0012] The impeller surface should be formed by an impeller base or impeller plate aligned perpendicular to the axis of rotation, with the axis of rotation running through its center. The impeller surface is closed and designed such that the pumped fluid exits the impeller radially and is thus discharged transversely, particularly at right angles to the axis of rotation.

[0013] The blades have a blade pressure surface facing forward in the direction of rotation and a blade suction surface facing rearward in the direction of rotation. The base body of the blade geometry of the blades of the first type and / or the blades of the second type can each extend outward from the axis of rotation in such a way that it runs straight (straight blading) and is optionally aligned orthogonally to the axis of rotation. Alternatively, the base body can have a curvature outward from the axis of rotation (curved blading), which extends in particular across the impeller surface and is greater than 0° and up to 270°.

[0014] Furthermore, the impeller can be characterized in that the blade geometry of the first-type blades and / or the second-type blades extends radially outward away from the axis of rotation and has a convex blade pressure surface and / or a concave blade suction surface. The shape of the blade suction surface and / or the blade pressure surface can be circular segment-shaped and / or cylindrical segment-shaped.

[0015] The pump impeller is suitable as a pump impeller for a vortex pump.

[0016] Furthermore, it may be advantageous if the blade pressure surface and / or the blade suction surface of the blade edge are inclined forward in the direction of rotation. The forward inclination has a positive effect on pressure buildup. Furthermore, the blade of the first type can be divided along a curve and / or a kink into a main body and the blade edge, with the blade edge preferably being arranged at a distance from the impeller surface. The inclination is realized by the curve or kink.

[0017] The blade edge can be inclined by an angle w1 with respect to an imaginary plane of rotation in which the impeller surface rotates (during operation) in the direction of rotation, wherein the angle w1 is preferably between 55° and 87° or between 60° and 80° or between 65° and 75°. This contributes to optimising the flow guidance. It is also advantageous if the blade geometry of the blade of the first type has a convex blade pressure surface and a concave blade suction surface, wherein in particular the convex blade pressure surface has the angled blade edge and / or the concave blade suction surface has the angled blade edge. The blade edge preferably has a free end to which no further element of the blade is connected. However, it is also optionally possible to additionally provide a blade of the first type with an inclined blade edge with a blade cover that extends beyond the blade suction surface.

[0018] Furthermore, it may be advantageous if the blade edge is arranged on a base body of the blade geometry of the first type of blade, wherein the base body adjoins the impeller surface and, in particular, the blade edge is arranged at a distance from the base body, and, in particular, forms a free end. The base body optimizes the momentum transfer to the fluid medium.

[0019] One aspect of the invention is that the blade geometry of the second type of blade comprises a base body that adjoins the impeller surface, and a blade cover that adjoins the base body, wherein a conveying channel is formed between the blade cover, the base body, and the impeller surface. The blade cover contributes to optimized flow guidance because it reduces turbulence. In this respect, the turbulence in the conveying channel is reduced. The conveying channel is bounded on three sides by the blade cover, the base body, and the impeller surface. It ensures a higher dynamic pressure within the flow guided therein. It is advantageous according to the invention that the blade geometry of the first type of blades does not have a blade cover.It is particularly advantageous if the blades of the first type and second type are arranged alternately in the direction of rotation, wherein the blades of the second type have blade covers and the blades of the first type do not have blade covers. The blades can be arranged with a uniform rotational angular spacing. However, it is also optionally possible to form an uneven distribution of the blades. In this case, it would be advisable to always arrange two adjacent blades as a pair closer to one another than to an adjacent pair. The larger spacing is then preferably formed between the optional blade edge and the opposite blade cover. The larger blade spacing should be formed between the blade of the first type equipped with a blade edge and the second type blade arranged in front of it in the direction of rotation and equipped with a blade cover.In other words, the opening angle between the blade pressure surface of the first type blade and the blade suction surface of a second type blade arranged in front of it in the direction of rotation is greater than the opening angle between the blade pressure surface of the second type blade and the blade suction surface of a first type blade arranged in front of it in the direction of rotation.

[0020] It can also be advantageous if the pump impeller has a single direction of rotation, and a blade channel formed in the direction of rotation between the second blade type and another of the blades is partially covered by the blade cover. This allows for particularly effective optimization of flow guidance and minimization of turbulence. The partial cover ensures sufficient inflow into the discharge channel.

[0021] It can be advantageous for the blade cover to cover between 30% and 70% of the blade channel in the direction of rotation, so that a gap remains free along the blade channel. The gap can extend over the full length of the blade channel, with the length extending radially to the axis of rotation, i.e. from the inside to the outside. The blade cover covers a width of the blade channel, with the width extending in the direction of rotation. The delivery channel is open at a radially outer blade wheel edge on the outer circumference of the pump impeller, so that a pumped fluid can escape from the delivery channel radially to the axis of rotation. This aspect helps to further optimize the flow guidance and minimize turbulence.

[0022] It is also advantageous if the base body is aligned parallel to the axis of rotation with a maximum deviation of + / -20°, preferably + / -10°, more preferably + / -5°, and particularly preferably + / -2°. Furthermore, the base body can be aligned orthogonally to the impeller surface with a maximum deviation of + / -20°, preferably + / -10°, more preferably + / -5°, and particularly preferably + / -2°. The base body thus stands quite straight on the impeller surface or extends perpendicularly (+ / - the specified deviation) away from the impeller surface. These aspects optimize flow guidance and minimize turbulence.

[0023] Furthermore, it can be advantageous if the blade cover is aligned parallel to an imaginary plane of rotation in which the impeller surface rotates (during operation) in the direction of rotation, with a maximum deviation of + / - 20°, preferably + / - 10°, more preferably + / - 5°, and particularly preferably + / - 2°, and / or is aligned orthogonally to the base body. Furthermore, the blade cover can be aligned parallel to the impeller surface with a maximum deviation of + / - 20°, preferably + / - 10°, more preferably + / - 5°, and particularly preferably + / - 2°. This aspect also contributes to optimizing flow guidance and minimizing turbulence.

[0024] It can also be advantageous if the pump impeller has a single direction of rotation and the blade cover projects beyond the base body opposite to the direction of rotation. In this respect, depending on the blade geometry of the second type of blade, the delivery channel can be arranged behind the corresponding base body in the direction of rotation, with the surface of the base body adjacent to the delivery channel preferably serving as the blade suction surface, and the opposite side of the base body serving as the blade pressure surface. This measure also ensures optimized flow guidance and minimizes turbulence.

[0025] It can also be advantageous if the blade geometry of the blade of the first type and / or the blade of the second type has a homogeneous material thickness with a maximum deviation of + / - 30%, preferably + / - 20%, more preferably + / - 10% and particularly preferably + / - 5%. Optionally, the blade pressure surface and blade suction surface can run parallel. The homogeneous material thickness optimizes the manufacturing process, in particular the cooling process during casting. The blade wheel is preferably made of metal. Due to the blade edge and blade cover described here, it is hardly possible to use a casting mold without cores anyway, which is why draft angles need to be taken much less into account and all surfaces can be optimized for efficiency.

[0026] Furthermore, it can be advantageous to provide the same number of blades of the first type and of the second type. This optimizes the interaction between the different blade types.

[0027] It is also advantageous if the first-type and second-type blades are arranged alternately one behind the other in the same direction of rotation of the pump impeller. The flow pattern through two adjacent blades directly influences each other. This allows for optimal utilization of the interaction of the different blade types.

[0028] It is also advantageous if the pump impeller is designed as a free-flow impeller. The impeller surface is a closed surface, and the axially flowing fluid is conveyed radially from the area of the impeller to the rotational axis. This achieves a redirection of the flow.

[0029] The invention is further achieved by a pump with a pump housing in which a pump impeller is rotatably mounted, with which a fluid medium can be conveyed from a pump inlet of the pump housing to a pump outlet of the pump housing, wherein the pump impeller is designed as described above and below, and the pump housing optionally has a housing element as described below, the flow channel of which is arranged between the pump inlet and the pump impeller. By applying at least one of the measures as described, the efficiency of the pump is optimized. The effects described above occur accordingly in combination, so that the pump characteristic curve is optimized. The pump impeller already reduces the backflow, which is further reduced by the surface structure of the housing element.

[0030] The optional housing element has an inner housing wall that delimits a flow channel for a fluid medium extending along a central axis, wherein the cross-section of the flow channel becomes larger in a main flow direction. The inner housing wall has a surface structure that is designed in such a way that it counteracts backflow against the main flow direction along the inner housing wall of the fluid medium. This measure increases the pressure build-up in the pump housing because backflow into the suction area of the pump is minimized. The surface structure particularly favors flow in the main flow direction. This correspondingly minimizes any loss of pump power, and larger flow rates in particular are pumped more efficiently. The flow guidance is optimized. The surface structure can therefore have at least one inflow surface that projects transversely into the backflow.The inflow surface swirls the backflow and reduces it accordingly. Preferably, there are no inflow surfaces extending transversely into the rotating flow in the circumferential direction. This does not slow down the rotation initiated by the pump impeller, but only the backflow.

[0031] According to a more detailed embodiment, the surface structure has at least one shoulder. The shoulder forms the inflow surface and counteracts the backflow. In addition, the shoulder forms a shadow for the main flow direction, in which a negative pressure is created when flowing over it. The backflow is then not only impeded at the shoulder, but the main flow then sucks the backflow back into the main flow. The shoulder can in particular protrude transversely into the backflow. Furthermore, the shoulder can be designed to be rotationally symmetrical. The shoulder can be designed with an undercut, in particular in such a way that the backflow flows at least slightly under the shoulder. In the main flow direction, this undercut hardly disrupts the flow. With regard to the backflow, the undercut can reinforce its deflection. For this purpose, the undercut can form a radius. There should be no undercuts in the main flow direction.This improves demoldability. Draft angles of at least 1.5° along the main flow direction are preferred. Furthermore, there should be no tapers in the main flow direction between multiple steps in the flow channel.

[0032] Furthermore, it is advantageous if the at least one shoulder is annular or at least ring-segment-shaped. The annular or at least ring-segment-shaped shoulder can extend in a circumferential direction around the central axis. This design makes the counteraction particularly efficient, and the shoulder can also be formed cost-effectively.

[0033] Furthermore, it is advantageous if the surface structure has at least one or two or three further steps. The steps are arranged at a distance from one another in a direction radial to the central axis and / or the main flow direction. The spacing and the number of steps can be adapted to the respective pump size. Optionally, the surface structure can also have at least five or at least six or at least ten or even significantly more than ten steps. The surface structure resulting from the additional steps further reduces backflow. Preferably, the step or steps is or are a macrostructure. For this purpose, the step preferably has a step height of at least 0.5 mm or at least 1.0 mm or at least 2.0 mm or at least 3.0 mm.

[0034] Preferably, the additional steps are arranged at equal spacing in the direction radial to the central axis and / or the main flow direction. The additional steps can be annular or at least ring-segment-shaped. The additional annular or at least ring-segment-shaped steps can extend in a circumferential direction around the central axis. This suppresses backflow particularly efficiently.

[0035] Alternatively, it may be advantageous if the shoulder is spiral-shaped and preferably winds radially outward from the central axis, preferably by more than 360°, more than 720°, more than 1080°, or even significantly more turns. This also allows for efficient suppression of backflow. The optionally rising winding of the spiral shoulder toward the pump impeller improves flow guidance toward the pump impeller.

[0036] It can also be advantageous if the shoulder has a wedge-shaped or trapezoidal cross-sectional profile. This allows an undercut to be formed. This is the basic shape, although radii can also be formed on the edges, for example. The backflow flows into this undercut and is slowed down. This suppresses the backflow particularly efficiently. In the main flow direction, however, the fluid simply flows over the shoulder. Other alternatives could include a round or oval cross-section. In principle, numerous different basic shapes can be considered for the shoulder shape. Preferably, however, these do not form a flow obstruction in the main flow direction, but only against the main flow direction.

[0037] In a special embodiment, the landing is designed in steps. A step is characterized in particular by the fact that one descends the step in the main flow direction and ascends it in the opposite direction. With optionally several stepped landings, a staircase of steps results.

[0038] It can also be advantageous if the inner housing wall has a conical basic shape on which the surface structure is formed. The inner housing wall can preferably widen in the main flow direction. This makes the housing element particularly suitable for a vortex pump. The conical basic shape is preferably straight. This minimally impedes fluid vortexing within the housing element. However, oblique conical basic shapes can also be considered, in particular slightly oblique conical basic shapes. This allows the pump connection, for example, to be positioned slightly differently. The conical basic shape is preferably a flat cone, namely in particular a cone with an opening angle of at least 20 degrees.

[0039] Furthermore, it may be advantageous if the housing element has a fluid inlet opening at the beginning of the flow channel in the main flow direction, wherein the fluid inlet opening is aligned with the central axis. The fluid inlet opening can be arranged in the assembly, particularly in the region of the pump inlet. For example, in this way, a cover forming the housing element can also be suitable for forming the pump inlet of a vortex pump.

[0040] It can also be advantageous if the housing element is designed as a detachable cover of a pump housing, in particular of the pump. The cover is detachable in the sense that it is attached to at least one other element of the housing by means of at least one detachable fastening means. Typical fastening means are screws and / or clamps. The detachable cover can be designed with a fastening flange and preferably have screw holes. Since the cover is detachable, the housing element can be dismantled and is then easy to maintain and replace where necessary. Alternatively or additionally, the housing element can form an impeller chamber of a pump housing. It is precisely here that potential backflows form on the inner wall due to the resulting vortex and the pressure at the pump outlet, which can be correspondingly reduced with the housing element.A further alternative or supplementary embodiment may consist of the housing element being an insert element in an impeller chamber of a pump housing. Such insert elements can be mounted inside an impeller chamber (e.g., screwed in place) and replaced as needed, particularly if, for example, abrasion or deposits impair the function of the step(s).

[0041] It may be advantageous if the pump impeller is positioned opposite the housing element in the direction of the main flow. The central axis of the housing element can be parallel and / or coaxial with the rotational axis of the pump impeller.

[0042] The housing element advantageously forms a wall of a pump hydraulic system, with the pump impeller being arranged in an impeller chamber of the pump hydraulic system. This is preferably a radial pump hydraulic system. The pump inlet should be aligned with the pump impeller. A free space without further flow guide elements is provided between the housing element and the pump impeller within the impeller chamber. The pump outlet is preferably aligned orthogonally to the pump inlet and leads radially from the pump impeller out of the impeller chamber. A spiral fluid vortex forms between the pump inlet, which is formed by the housing element, and the pump impeller and leads to a backflow along the inner wall of the housing element, which then collides with the surface structure and swirls. The inhibition of backflow is thus particularly effective.

[0043] It can also be advantageous if the pump is a vortex pump. These advantages are particularly evident with vortex pumps.

[0044] Further features, details, and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show: Fig. 1a top view of a pump impeller; Fig. 2a perspective view of the pump impeller of the Fig. 1 from below; Fig. 3 a perspective view of a pump impeller from above, which does not belong to the claimed invention; Fig. 4 a schematic development of a pump impeller, which does not belong to the claimed invention; Fig. 5 a perspective view of a housing element; Fig. 6 a cross section through the housing element of the Fig. 5; Fig. 7 a schematic view from above of a housing element with ring-segment-shaped shoulders; Fig. 8 a schematic view from above of a housing element with a spiral-shaped shoulder; Fig. 9 a cross-section of a shoulder; Fig. 10 a cross-section of an alternative shoulder; and Fig. 11 a cross-section through a pump.

[0045] After Fig. 1 and Fig. 2A pump impeller 1 has an imaginary axis of rotation DA around which the pump impeller 1 is intended to rotate during operation (hereinafter simply referred to as the axis of rotation DA). The axis of rotation DA runs through an impeller hub 14 in the center of an impeller surface 11, wherein the impeller hub 14 has a keyway 15. A shaft of a drive unit of a pump can be received in the impeller hub 14. The axis of rotation DA is coaxial with the impeller hub 14. The impeller surface 11 is closed and designed such that a pumped fluid leaves the pump impeller 1 radially. The pumped fluid is discharged at a right angle to the axis of rotation DA.

[0046] The pump impeller 1 also has three blades of the first type 2 and three blades of the second type 3, which are arranged on the impeller surface 11. The impeller surface 11 is aligned orthogonally to the rotational axis DA, and the pump impeller 1 is designed as a free-flow impeller. The impeller surface 11 is closed between the blades 2 and 3, so that no fluid can pass through the pump impeller 1 parallel to the rotational axis DA.

[0047] The pump impeller 1 can rotate in a direction of rotation DR around the rotation axis DA. This is the preferred direction of rotation DR during operation. The first-type blades 2 and the second-type blades 3 are arranged alternately one behind the other in the direction of rotation DR.

[0048] The blades of the first type 2 have a blade pressure surface 24 and a blade suction surface 23. The blades of the second type 3 correspondingly have a blade pressure surface 34 and a blade suction surface 35. The blade pressure surfaces 24 each run convexly in a direction R radially away from the axis of rotation DA. The blade suction surfaces 23 each run concavely in the direction R, which corresponds to the radius. This results in what is known as curved blading. Along this course of the blades 2, 3, the blade pressure surfaces 24 and blade suction surfaces 23 form circular segments. The blades of the first type 2 and second type 3 have a homogeneous material thickness 25, 37. The course of the respective blade pressure surface 24, 34 and blade suction surface 23, 35 is therefore at least essentially parallel.

[0049] The blade geometry of the first type 2 blade differs from the blade geometry of the second type 3 blade.

[0050] The blade geometry of the first type 2 blade has a base body 21 that adjoins the impeller surface 11. The base body 21 runs parallel to the axis of rotation DA and is aligned orthogonally to the impeller surface 11. A blade edge 22 adjoins the base body 21. The blade edge 22 is therefore spaced apart from the impeller surface 11. A curvature 27 runs between the base body 21 and the blade edge 22. Alternatively, this can be a kink. Due to the curvature 27, the blade edge 22 is inclined by an angle w1 of approximately 70° with respect to an imaginary plane of rotation in which the impeller surface 11 rotates (during operation) in the direction of rotation DR. In particular, the angle w1 should be between 55° and 87°, or between 60° and 80°, or between 65° and 75°. Accordingly, the blade edge 22 is inclined at an angle w2 of approximately 20° relative to the base body 11, which is aligned orthogonally to the plane of rotation.Due to the homogeneous material thicknesses 25, 37, the blade pressure surface 24 and the blade suction surface 23 are parallel. Thus, both the blade pressure surface 24 and the blade suction surface 23 are inclined at angles w1 and w2. Furthermore, the blade edge 22, and with it both the blade pressure surface 24 and the blade suction surface 25, are inclined forward in the direction of rotation DR. The blade edge 22 has a free end 26, in that no further element adjoins the blade edge 22. The base body 21, together with the blade edge 22, forms the blade pressure surface 24 and the blade suction surface 23.

[0051] The second type of blade 3 has a base body 31 and a blade cover 32. The base body 31 adjoins the impeller surface 11 and is aligned orthogonally to the base body 31. Furthermore, the base body 31 is aligned parallel to the axis of rotation DA. The blade cover 32 adjoins the base body 31 and is arranged at a distance from the impeller surface 11. In particular, the blade cover 32 is aligned parallel to the imaginary plane of rotation in which the impeller surface 11 rotates (during operation) in the direction of rotation DR. A conveying channel 13 formed in this way is bounded on three sides by the blade cover 32, the base body 31 and the impeller surface 11. The blade cover 32 is also aligned orthogonally to the base body 31 and the axis of rotation DA. The blade cover 32 is also aligned parallel to the impeller surface 11.The blade cover 32 projects beyond the base body 31 opposite to the direction of rotation DR, thus beyond the blade suction surface 35.

[0052] The conveying channel 13 is defined between the blade suction surface 35 of the base body 31 and the blade cover 32 of the second type of blade 3, as well as the impeller surface 11. A blade channel 12 is formed between adjacent blades 2, 3 in the direction of rotation DR. Part of the blade channel 12 is formed by the conveying channel 13. The blade channel 12 is partially covered, approximately 25-75%, by the blade cover 32, so that a gap 16 for the inflow of fluid remains free along the blade channel 12. The gap 16 extends over the full length I of the impeller channel 12, with the length I running radially to the axis of rotation DA. The blade cover 22 covers the width b of the blade channel 12, with the width b extending in the direction of rotation DR. The conveying channel 13 is open at a radially outer impeller edge 17 so that a conveyed fluid can exit the conveying channel 13 in the radial direction R.The impeller edge 17 is located on the outer circumference of the pump impeller 1.

[0053] One in Fig. 3 The pump impeller 1 shown differs from the pump impeller of the Fig. 1 and 2 that, instead of the three blades of the second type, it has three blades of the first type 2. Thus, the pump impeller 1 has exclusively blades of the first type 2, namely, in this case, six. It therefore does not belong to the claimed invention.

[0054] The schematic sketch of the Fig. 4 shows a development of a pump impeller 1, where the blade geometries differ from those of the Fig. 3 differ in that the blade edge 22 does not form a free end 26. Instead, a blade cover 32 is attached here, which basically has the same features as the blade cover of the second type 3 blades of the Fig. 1 and 2While the blade edge 22 is inclined forward in the direction of rotation, i.e., toward the blade pressure surface 24, the blade cover 32 projects rearward from the end of the blade edge 22 in the direction of rotation, in particular beyond the blade suction surface 23. This pump impeller 1 also does not belong to the claimed invention.

[0055] A further modification of the pump impeller 1 according to the invention can consist in that, in contrast to the representation of the Fig. 1 and 2it is provided that pairs of a blade of the first type 2 and a blade of the second type 3 can be provided, wherein a larger blade spacing is formed between the first type blade 2 equipped with a blade edge 22 and the adjacent second type blade 3 equipped with a blade cover 32. In particular, the opening angle between the blade pressure surface 24 of the blade of the first type 2 and the blade suction surface 35 of an adjacently arranged blade of the second type 3 should be greater than the opening angle between the blade pressure surface 34 of the blade of the second type 3 and the blade suction surface 23 of an adjacently arranged blade of the first type 2.

[0056] According to Fig. 5 and Fig. 6a housing element 100 is designed as a detachable cover, in particular with a fastening flange, of a pump 200. The housing element 100 advantageously has screw holes 107 in the fastening flange. The housing element 100 also has an inner housing wall 103. The inner housing wall 103 has a conical basic shape that extends along a central axis M. The inner housing wall 103 delimits a flow channel 105 for a fluid medium that can be conveyed through the flow channel 105 in a main flow direction H. The main flow direction H is coaxial with the central axis M. A fluid inlet opening 104 is provided at the beginning of the main flow direction H. The flow channel 105 widens in the main flow direction H. The surface structure 101 is designed such that it counteracts backflow against the main flow direction H along the inner housing wall 103.

[0057] The surface structure 101 therefore has an inflow surface 106 that projects transversely into the return flow. The inflow surface 106 has a plurality of shoulders 102 that form an undercut with respect to the conical housing inner wall 103. The shoulders 102 are each rotationally symmetrical with respect to the central axis M. In this sense, the shoulder 102 is annular, with the shoulder running in a circumferential direction U around the central axis M. A total of four shoulders 102 are provided here, although more or fewer shoulders 102 can also be provided. The shoulders 102 are arranged at equal distances in the main flow direction H and in a direction R2 radial thereto. The shoulders 102 thus run parallel to one another. The other shoulders 102, the number of which is variable, are also annular.

[0058] As an alternative to the annular design, paragraphs 102 can be Fig. 7be formed in the shape of a ring segment, wherein the shoulders 102 extend in the circumferential direction U around the central axis M and are arranged at equal distances in the main flow direction H and the direction R2. Another possibility is to form the shoulder 102 in a spiral shape, which is wound outwards radially to the central axis M, as Fig. 8 shows. With several rotations of the spiral, several steps result, so to speak, on average, each of which forms an obstacle to backflow.

[0059] As in Fig. 9 As shown, a shoulder 102 has a wedge-shaped cross-section Q. The shoulder 102 may also have a trapezoidal cross-section Q according to the Fig. 10Further alternatives may have a round or oval cross-section. Preferably, however, there is no cross-sectional narrowing due to the shoulders 102 in the direction of the main flow direction H. Conversely, a gradual cross-sectional narrowing results in the direction opposite to the main flow direction H.

[0060] A pump 200 according to the invention, which is designed as a free-flow impeller pump, has Fig. 11 a pump housing 201. In the pump housing 201, a pump impeller 1 according to the invention is provided, as is shown for example in the Fig. 1, 2 , 3 and 4 The pump impeller 1 is rotatably mounted and is driven by a drive unit 202.

[0061] The fluid medium can be conveyed through the pump housing 201 from a pump inlet 203 to a pump outlet 204. The pump inlet 203 and the pump outlet 204 are aligned orthogonally to each other. The pump outlet 204 leads radially from the pump impeller 1 out of an impeller chamber 206 in which the pump impeller 1 is located.

[0062] The pump housing 201 has a housing element 100 according to the invention. The housing element 100 forms a wall of the impeller chamber 206. The pump impeller 1 is arranged in the main flow direction H opposite the housing element 100, wherein the central axis M is parallel and coaxial with the rotation axis DA. The fluid inlet opening 104 of the housing element 100 is located in the region of the pump inlet 203. The flow channel 105 is arranged between the pump inlet 203 and the pump impeller 1. A free space 207 is formed in the flow channel 105 and between the pump inlet 203 and the pump impeller 1, in which no further flow guide elements are provided. A vortex forms in this space 207 because the fluid is stimulated to rotate by the pump impeller 1. An overpressure at the pump outlet 204 then leads to a backflow on the inner wall of the housing element 100.The steps here form flow obstacles for the return flow and direct the return flow back into the main flow direction H.

[0063] Alternatively, the housing element 100 can be designed as a detachable cover with a fastening flange and can be fastened to the remaining pump housing 201 by means of screws as fastening means.

[0064] Another alternative may be for the housing element 100 to be inserted into the interior of the pump housing 101. For this purpose, the pump housing 101 should form a seat for the housing element. List of reference symbols 1 Pump impeller 103 Housing inner wall 11 Impeller surface 104 Fluid inlet opening 12 blade channel 105 flow channel 13 conveyor channel 106 Inflow area 14 wheel hub 15 keyway 200 pump 16 gap 201 Pump housing 17 paddle wheel edge 202 drive unit 203 Pump inlet 2 Shovel of the first type 204 Pump outlet 21 Basic body 206 Impeller chamber 22 blade edge 207 blank 23 Blade suction area 24 Blade pressure area b Width of the blade channel 25 Material thickness l Length of the blade channel 26 free end DR Direction of rotation 27 curvature THERE axis of rotation 3 Second type shovel H Main flow direction 31 Basic body R Direction radial to the axis of rotation 32 Shovel cover R2 radial direction 34 Blade pressure area M central axis 35 Blade suction area Q Cross-sectional profile 37 Material thickness U circumferential direction w1 angle 100 Housing element w2 angle 101 Surface structure 102 heel, shoulder, step

Claims

1. Pump impeller (1) with an impeller surface (11) on which blades (2, 3) are arranged, wherein at least one of the blades (2, 3) is a blade of the first type (2), wherein at least one of the blades (2, 3) is a blade of the second type (3), wherein the blade geometry of the blade of the first type (2) differs from the blade geometry of the blade of the second type (3), wherein the blade geometry of the blade of the first type (2) has a blade edge (22) which is inclined towards the front in the rotational direction (DR), and wherein the blade geometry of the blade of the second type (3) comprises a base body (31) which adjoins the impeller surface (11), characterized in that the blade geometry of the blade of the second type (3) comprises a blade cover (32) which adjoins the base body (31), wherein a pumping channel (13) is configured between the blade cover (32), the base body (31) and the impeller surface (11), wherein the blade geometry of the blades of the first type (2) does not have a blade cover.

2. Pump impeller (1) according to Claim 1, characterized in that the blade edge (22) is arranged on a base body (21) of the blade geometry of the blade of the first type (2), wherein the base body (21) adjoins the impeller surface (11) and, in particular, the blade edge (22) is arranged spaced apart from the base body (21).

3. Pump impeller (1) according to one of Claims 1 and 2, characterized in that this pump impeller has a rotational direction (DR) and the blade cover (32) protrudes over the base body (31) counter to the rotational direction (DR).

4. Pump impeller (1) according to one of the preceding claims, characterized in that the same number of blades of the first type (2) and blades of the second type (3) is provided.

5. Pump (200) with a pump housing (201) in which a pump impeller (1) is rotatably mounted, a fluid medium being able to be pumped from a pump inlet (203) of the pump housing (201) to a pump outlet (204) of the pump housing (201), wherein the pump impeller (1) is configured according to one of preceding Claims 1 to 4.

6. Pump (200) according to Claim 5, characterized in that the pump housing (201) has a housing element (100), wherein the housing element (100) has a housing inner wall (103) which defines a flow channel (105) for a fluid medium extending along a central axis (M), wherein the cross section of the flow channel (105) increases in a main flow direction (H), wherein the housing inner wall (103) has a surface structure (101) which is configured such that it counteracts a return flow counter to the main flow direction (H) along the housing inner wall (103) of the fluid medium, wherein the flow channel (105) of the housing element (100) is arranged between the pump inlet (203) and the pump impeller (1).

7. Pump (200) according to Claim 6, characterized in that the surface structure (101) of the housing element (100) has at least one shoulder (102).

8. Pump (200) according to Claim 7, characterized in that the at least one shoulder (102) is configured in an annular or annular segment-shaped manner.

9. Pump (200) according to one of Claims 7 and 8, characterized in that the surface structure (101) has at least one or two or three further shoulders (102).

10. Pump (200) according to Claim 9, characterized in that he shoulder (102) is configured to be spiral-shaped and preferably is wound radially outwardly starting from the central axis (M).

11. Pump (200) according to one of Claims 8 to 10, characterized in that the shoulder (102) is configured to be step-shaped.

12. Pump (200) according to one of Claims 6 to 11, characterized in that the housing inner wall (103) has a conical basic shape, the surface structure (101) being configured thereon.

13. Pump (200) according to one of Claims 6 to 12, characterized in that the pump impeller (1) is arranged in the direction of the main flow direction (H) relative to the surface structure (101) of the housing element (100).