An assembly including a cutter head and an impeller for a pump of a solid-laden liquid

Abstract

The subject of the invention is an assembly comprising a cutting head (1) and an impeller (3) for a pump for a liquid carrying solids, wherein the cutting head (1) is fixedly connected to the impeller (3) in the axial extension of the impeller for co-action with a cutting ring (2), and the cutting head has a cutting head base body (8) with a plurality of cutting segments (11) having cutting head cutting edges (13) for comminuting the solids, which extend radially away from the cutting head base body (8), the impeller (3) has a plurality of blades (23) having an inlet edge (24) arranged spaced apart from the cutting head cutting edges (13) and extending substantially parallel to the cutting head cutting edges (13), and the cutting head cutting edges (13) are arranged radially in front of the inlet edges (24) in the direction of rotation of the impeller (3).

Description

Technical Field

[0001] The present invention relates to an assembly comprising a cutting head and an impeller for a pump carrying a liquid containing solids, wherein the cutting head is fixedly connected to the impeller at an axial extension of the impeller to cooperate with a cutting ring, and the cutting head has a cutting head base with a plurality of cutting segments having cutting head cutting edges for crushing solids, the cutting head cutting edges extending radially away from the cutting head base. Background Technology

[0002] Solid mixtures in liquids (such as sewage) can clog pumps or pipes. To prevent such clogging, a so-called cutting device is used. This device is located in front of the pump's suction area to break up the solids contained in the liquid.

[0003] Cutting devices known from the prior art typically have a stationary component (called the cutting face or cutting element) and a rotating component (called the cutting head). Depending on the application of the cutting device, circular, conical, or cylindrical cutting faces can be used. The cutting face (also called a cutting screen) has openings through which liquid flows to the impeller of the pump. A flat or conical configuration of the cutting face is called a cutting plate. A cylindrical configuration of the cutting face is called a cutting ring.

[0004] While such a cutting device may provide excellent cutting performance in its new condition, the device itself can become clogged, blocked by solids, or solids may become lodged in front of the pump's suction area, thus closing off the suction zone. Furthermore, cutting devices connected upstream of the pump typically negatively impact the pump's efficiency and characteristic curves due to their influence on the flow rate into the pump. Summary of the Invention

[0005] In light of this, the object of the present invention is to provide an assembly comprising a cutting head and an impeller for a pump carrying a liquid containing solids, which, compared with solutions known from the prior art, operates more safely, reduces maintenance and / or assembly costs, and simultaneously enables the pump to achieve high hydraulic efficiency.

[0006] The object of the present invention is achieved by the features of an assembly of a cutting head and an impeller. Advantageous configurations are given in the specific embodiments.

[0007] Accordingly, this objective is achieved by an assembly comprising a cutting head and an impeller for a pump carrying a liquid containing solids, wherein

[0008] The cutting head is fixedly connected to the impeller on the axial extension of the impeller to work in conjunction with the cutting ring. The cutting head has a cutting head base with multiple cutting segments having cutting edges for crushing solids, which extend radially away from the cutting head base.

[0009] The impeller has multiple blades, which have inlet edges that are spaced apart from and generally parallel to the cutting edge of the cutting head.

[0010] The cutting edge of the cutting head is arranged radially in front of the inlet edge in the direction of impeller rotation and, in particular, radially overlaps with the inlet edge.

[0011] The key to the proposed solution lies in the cutting edge of the front-mounted cutter head, which enables better flow in the impeller region and thus a higher pump characteristic curve. The solid material passing through the cutting device, consisting of the cutting ring and the cutter head, does not directly collide with the inlet edge. This prevents the fibrous components from becoming entangled around the inlet edge and clogging the pump. The inlet edge extending generally parallel to the cutting edge of the cutter head specifically means that the cutting edge of the cutter head and the inlet edge extend parallel to each other or pivotally relative to each other at an angle of ≤2°, 5°, or 10°.

[0012] A pump is generally a fluid machine that uses rotational motion and dynamic force to transport a medium that is primarily liquid. Preferably, the pump is designed as a rotary pump. In a rotary pump, in addition to the tangential acceleration of the medium / liquid, centrifugal force generated in the radial flow is used for transport; therefore, such a pump is also called a centrifugal pump. Preferably, the pump can be used in the hydraulic systems of buildings, for example, as a sewage pump.

[0013] During normal pump operation, the motor housing can be positioned above the pump housing, within which an impeller driven by the motor via a motor shaft is housed to transport fluid. The motor housing and pump housing are fixedly connected and / or can be designed as a single unit. Preferably, the motor shaft extends inward from the motor housing into the pump housing on the drive side, and / or the impeller on the drive side is fixedly connected to the motor shaft.

[0014] The liquid preferably includes water or other liquid media, such as sewage. The liquid may include solids, such as any kind of contaminant, particularly excrement, sediment, sludge, sand, or even smaller pieces of wood, shrubbery, textiles, rags, or the like. Preferably, the motor housing and / or pump housing are made of metal, especially cast iron or stainless steel, and / or of plastic.

[0015] The cutting edge of the cutting head is preferably arranged to overlap with the inlet edge in the radial direction. This specifically means that the inlet edge is at least partially arranged at the same axial height as the cutting edge of the cutting head and / or at least partially arranged in a common radial plane with the cutting edge of the cutting head. Preferably, the axial extension of the cutting edge of the cutting head is greater than the axial extension of the inlet edge.

[0016] Preferably, the cutting head is screwed onto the impeller and designed to be fixed to the impeller in such a way that the cutting head and the impeller are designed as a two-piece unit. The cutting head can also be implemented as a single piece with the impeller, for example, made of metal or plastic. In particular, the radial arrangement in front of the inlet edge in the direction of impeller rotation means that the inlet edge and the cutting edge of the cutting head are not on the same radial line, but are arranged to be fixed ahead of it in the direction of rotation, for example, by a few degrees or millimeters.

[0017] The cutting segments preferably extend radially away from the cutting head base and / or are arranged at regular intervals and / or are designed as a single piece with the cutting head base. Preferably, axially extending cutting edges of the cutting head are provided on the radially outer side of the cutting segments; these cutting edges preferably interact with the cutting teeth of the cutting ring to pulverize solids. Through the rotational motion of the motor shaft, for example, the textile material obtained by the cutting edges of the cutting head can engage with the cutting teeth as a solid, thereby pulverizing the textile and thus preventing pump blockage.

[0018] According to a preferred improvement, the cutting edges of the cutting head extend generally axially. Generally axially means, for example, that a shaped bevel may be included and / or the cutting edges of the cutting head may pivot ≤3%, 5%, or 10% axially. Furthermore, the cutting edges of the cutting head may be designed in a serrated form.

[0019] According to a preferred improvement, the cutting edge of the cutting head is arranged in front of the inlet edge at an angle α ≥ 1.5°, 2.5°, 5°, or 10°, and especially α ≤ 2.5°, 5°, 10°, 15°, 20°, 30°, or 45°. Furthermore, angles such as α ≥ 15° or 20°, and especially α ≤ 60°, 75°, or 90°, are also conceivable. As previously implemented, this design achieves better flow in the impeller region and improves the pump characteristic curve. Moreover, since the solids already cut by the cutting device consisting of the cutting ring and the cutting head do not directly collide with the inlet edge, the fibrous components of the solids can be prevented from becoming entangled around the inlet edge and clogging the pump.

[0020] According to another preferred design, the impeller has an impeller opening with a cutting head arranged within it, and the inlet edges are arranged to be radially spaced outward from the edge of the impeller opening. Preferably, the spacing is ≥2, 5, 10, 15, or 20 mm. Such spacing also contributes to better flow in the impeller region and improves the pump characteristic curve.

[0021] According to a preferred improvement, the number of cutting edges of the cutting head is equal to, unequal to, or double the number of blades and / or inlet edges. In other words, the inlet edges are preferably associated with the cutting head cutting edges. In cases where the cutting head has cutting edges with different axial extension lengths, the longer cutting edges preferably correspond to the number of blades, while the shorter cutting edges do not reach the blades axially. In this case, the number of longer cutting edges is preferably equal to the number of blades and / or inlet edges. The inlet edges preferably extend in the axial direction.

[0022] According to another preferred design, the impeller has a bearing disc on the motor side with a hub for receiving the motor shaft of the pump and a cover disc on the suction side, with blades disposed between the bearing disc and the cover disc. The impeller is preferably designed as a closed double-channel impeller. Alternatively, the impeller can be designed as an open impeller as known from the prior art. The impeller is preferably connected to the motor shaft in a fixed position via force fit and / or form fit. The bearing disc and / or cover disc are preferably designed to be circular and arranged parallel to each other, while the blades extend radially outward in a spiral manner between the opening and the outer edge of the impeller. In the case where the cutting head has four cutting segments with cutting edges on the outside (where opposite segments are recessed), the radial position of the cutting head on the hub is preferably selected such that the consecutive cutting segments are located in the regions of the two inlet edges of the impeller.

[0023] According to a preferred improvement, at least two cutting edges of the cutting head have axial extensions of different lengths, and the cutting edge with the longer axial extension is arranged to be spaced apart from the inlet edge. Higher and thus better pump characteristic curves are achieved through the different lengths of the cutting edges. The longer cutting edge can interact with the impeller blades, while the shorter cutting edge has an additional effect on the solids, thereby achieving better cutting results and reducing pump clogging. For example, better cutting results can be achieved when one-third of the cutting edge is made longer to interact with the impeller blades, and two-thirds of the cutting edge is made shorter. Preferably, to achieve rotational symmetry, at least two cutting edges are made shorter, and multiples thereof are made longer. More preferably, the cutting head is designed to be rotationally symmetrical. Furthermore, the cutting edges can be designed in a serrated form. Preferably, the shorter cutting edge is positioned between two longer cutting edges.

[0024] The object of the invention is also achieved by a pump having a pump housing and the components as described above arranged within the pump housing, wherein a cylindrical sealing gap is provided between the pump suction side and the pump housing for radial sealing of the impeller. According to a preferred improvement, the pump has a cut ring fixedly disposed on the pump, or the cut ring and the components as described above, wherein for radial sealing, the cut ring at least partially surrounds the impeller to form a tapered sealing gap. A reliable seal of the pump is achieved through the proposed sealing gap. A shaft seal ring and / or a split ring may be provided in the sealing gap. The shaft seal ring preferably has a sealing lip located on the impeller and preferably radially pressed against the impeller by a hose spring and / or a worm spring. The shaft seal ring may be introduced into the pump housing in a tight-fitting manner and / or preferably implemented as a radial shaft seal ring. A V-ring seal made of nitrile rubber may also be provided.

[0025] According to a preferred improvement of the pump and / or the cutting ring fixedly mounted on the pump and the aforementioned components, the cutting ring has multiple cutting teeth that interact with the cutting edge of the cutting head to pulverize the acquired solids. Such a pump enables better flow at the impeller inlet, thereby achieving a higher pump characteristic curve because it reduces interference with the flow between the blades or the blade channels formed by these blades compared to designs known from the prior art. With the cutting edges of the aforementioned cutting heads of varying lengths, larger diameter solids can be better retained until these solids are sufficiently pulverized by the outer cutting ring, resulting in better cutting results and a lower risk of clogging. Attached Figure Description

[0026] The invention will now be explained in detail with reference to the accompanying drawings and preferred embodiments.

[0027] In the attached diagram:

[0028] Figure 1 A pump according to a preferred embodiment of the present invention is shown in a partial cross-sectional view.

[0029] Figure 2 Two perspective views illustrate the cutting head of the pump according to a preferred embodiment of the present invention.

[0030] Figure 3 The cutting ring of the pump according to a preferred embodiment of the present invention is shown in two perspective views (top) and a partial cross-sectional view (bottom).

[0031] Figure 4 The impeller and cutting head of the pump according to a preferred embodiment of the present invention are shown in perspective view (left) and top view (right). Detailed Implementation

[0032] Figure 1 A pump according to a preferred embodiment of the present invention is shown in a partial cross-sectional view. The pump (implemented as a submersible sewage pump) has a cutting device connected upstream of the impeller 3, the cutting device including... Figures 2 to 4 The cutting head 1 and cutting ring 2 are shown in the diagram. The pump's cutting head 1, cutting ring 2, and impeller 3 do not necessarily have to be designed as described below. This means that the pump can, for example, have the cutting head 1 described below, but the cutting ring 2 and impeller 3 can be designed differently from those described below. The same applies to the cutting ring 2 and impeller 3. In this regard, it is entirely feasible that, for example, the cutting ring 2 is designed as described below, the cutting head 1 need not be designed as described below.

[0033] Figure 1 A partial cross-sectional view shows a portion of the pump housing 4, above which is a housing (not shown) for the pump motor, which is located during normal operation of the pump. The motor drives an impeller 3 (not shown) via a motor shaft, which draws in liquid containing solids from the suction side 5 located below the pump housing 4. In this regard, the terms "axial" and "radial" as used below refer to the axial extension of the motor shaft, respectively.

[0034] The cutting head 1 is fixedly connected to the impeller 3 by means of cutting head bolts 6, particularly by force and / or form fitting, and rotates accordingly with the impeller 3 during pump operation. A cylindrical cutting ring 2 surrounding the cutting head 1 is fixedly connected to the pump housing 4 relative to this by means of multiple cutting ring bolts 7. A radial seal is provided between the cutting ring 2 and the impeller 3. The cutting head 1 extends into the suction side 5, causing the pumped liquid to first flow from the suction side 5 through the gap between the cutting head 1 and the cutting ring 2, so as to be subsequently conveyed through the impeller 3. Through the rotational movement of the cutting head 1 relative to the cutting ring 2, solids contained in the liquid are pulverized before reaching the impeller 3.

[0035] Figure 2 Two perspective views illustrate the cutting head 1 of a pump according to a preferred embodiment of the present invention. The left side shows a perspective top view of the cutting head 1 from the suction side 5, while the right side shows a perspective top view of the cutting head 1 from the side where it is assigned to the impeller 3. The cutting head 1 has a cylindrical, rotationally symmetrical cutting head base 8 made of metal, through which holes 9 for receiving cutting head bolts 6 for fastening at the impeller 3 extend axially.

[0036] Four cutting segments 11 arranged at regular intervals are provided on the outer peripheral surface 10 of the cutting head base 8. These cutting segments are designed as a single piece with the cutting head base 8. The cutting segments 11 extend radially away from the cutting head base 8. Furthermore, all cutting segments 11 extend axially toward the impeller 3 from the liquid inlet side 12 of the suction side 5 of the cutting head 1, which is opposite to the impeller 3, thereby forming an axially extending cutting edge 13 of the cutting head.

[0037] In the left figure, the cutting segments 11 or their cutting edges 13, arranged at approximately 180° opposite angles, extend axially to equal lengths, that is, from the liquid inlet side 12 of the cutting head 1 facing the suction side 5 to the opposite side 14 facing the impeller 3. However, the two cutting segments 11 or their cutting edges 13, arranged at a 90° interval, do not extend axially from the liquid inlet side 12 to the side 14. In other words, the two cutting edges 13 have axial extensions of different lengths relative to the other two cutting edges 13, because the first portion of the cutting edge 13 extends substantially from the liquid inlet side 12 or over the entire axial extension of the cutting head 1, while the second portion extends only a portion of the entire axial extension of the cutting head 1 from the liquid inlet side 12.

[0038] In other words, the second portion of the cutting segment 11 is shortened by about half relative to the first portion, with the oppositely arranged cutting segments 11 being implemented accordingly. The shortened portion of the cutting segment 11 on the axial extension is implemented without the cutting edge 13 of the cutting head. The shortened cutting segment 11 has a constant radial diameter up to about half of the axial extension of the cutting head 1, and then gradually narrows in diameter in a teardrop shape toward the side 14 facing the impeller 3. The cutting head 1 has a surrounding cylindrical joint 15 on its axial side 14 facing the impeller 3, which is integrally implemented with the cutting head base 8 and terminates flush with the cutting edge 13 of the cutting head in terms of its radial outer diameter. The joint 15 gradually narrows in diameter from the side 14 toward the liquid inlet side 12 in a manner that transitions uniformly into the cutting head base 8.

[0039] In the direction of rotation toward the cutting head 1, the cutting segment 11 extends concavely radially away from the cutting head base 8 to the corresponding cutting edge 13 of the cutting head. Conversely, in the direction of rotation away from the cutting head 1, the extending cutting segment 11 extends linearly radially away from the cutting head base 8 to the cutting edge 13 of the cutting head. A similar description applies to the teardrop-shaped narrowing portion of the shortened cutting segment 11.

[0040] For further flow optimization, the cutting segment 11 and the cutting edge 13 of the cutting head are inclined at the liquid inlet side 12 of the cutting head 1 opposite to the impeller 3, such that... Figure 2 As can be seen from the above. In order to crush the obtained solids, the cutting head 1 can work together with the cutting edge 13 of its cutting head and the cutting ring 2 with multiple cutting teeth 16 fixedly set on the pump as described below.

[0041] Figure 3 The cutting ring 2 of the pump according to a preferred embodiment of the present invention is shown in two perspective views (top) and a partial cross-sectional view (bottom). The cutting ring 2 has an annular cutting ring base 18 forming an opening 17. Figure 1 In the installed state shown, the cutting head 1 is guided through the opening 17. As previously described, the cutting ring 2 is fixed to the pump housing 4 of the pump in a positional manner by means of three cutting ring bolts 7 distributed around the opening 17 along the axial extension of the impeller 3.

[0042] A plurality of cutting teeth 16 are arranged at regular intervals around the opening 17 at the rotationally symmetrical cutting ring base 18. These cutting teeth have corresponding inner cutting edges 19 axially oriented in the direction toward the impeller 3 and outer cutting edges 19 axially oriented away from the impeller 3 in the direction toward the suction side 5 of the pump. The cutting edges 19 work together with the cutting edge 13 of the cutting head when the cutting head 1 rotates.

[0043] The corresponding three cutting teeth 16 extend axially inward into the pump housing 4 in the direction away from the cutting ring base 18 and towards the impeller 3, and the corresponding three cutting teeth 16 extend outward from the pump housing 4 in the direction towards the suction side 5, as shown in... Figure 1 As shown in the figure. Similarly, four, eight, twelve or more cutting teeth 16 can be provided, and the orientation of these cutting teeth is alternately outward and inward. In the axial extension direction, an inner cutting edge 19 and an outer cutting edge 19 are respectively designed around the opening 17 between the tip of the outer cutting tooth 16 and the tip of the inner cutting tooth 16.

[0044] The outward-extending cutting teeth 16 Figure 3 The cutting ring base 18 is shown below in the cross-sectional view below, while the inwardly extending cutting teeth 16 are shown above in the cross-sectional view above the cutting ring base 18. Figure 3 The perspective view at the upper right corresponds to this presentation and shows a view of the cutting ring 2 from the suction side 5, while the perspective view at the upper left shows a view of the cutting ring 2 from the pump housing 4.

[0045] At least in the outwardly extending cutting teeth 16, radially outwardly extending material recesses 20 are introduced accordingly after the cutting edge 19 along the rotation direction of the impeller 3. Such material recesses 20 are also introduced in the inwardly extending cutting teeth 16. This means that, in the top view, the outer diameters of the cutting teeth 16 extending wavyly or sinusoidally around the opening 17 are equal, while the inner diameters are larger in the regions of the material recesses 20 relative to the regions of the cutting teeth 16 without material recesses.

[0046] Alternatively or additionally, radially outwardly extending pouch-shaped axial recesses 22 are introduced into the cutting ring base 18 in the recesses 21 located between at least two outwardly extending cutting teeth 16. Here, pouch-shaped axial recesses 22 are introduced in both the recesses 21 located between the outwardly and inwardly extending cutting teeth 16. The recesses 22 extend radially outward from the bottom of the recess, thereby causing the cutting ring base 18 to flatten radially outward in the recesses 21. The material recesses 20 and recesses 21 are provided on all the cutting teeth 16 or between these cutting teeth, and can be manufactured by milling or by corresponding injection molding of the metal cutting ring 2.

[0047] For example, especially from Figure 3As shown in the figure below, the outer cutting edge 19 of the recess 21 between the two outwardly extending cutting teeth 16 overlaps with the inner cutting edge 19 of the recess 21 between the two inwardly extending cutting teeth 16 in the axial direction. Thus, there is no radially surrounding, uninterrupted joint on the cutting surface of the cutting ring 2 formed by the cutting edges 19. Along the rotation direction of the impeller 3, the cutting angle of the cutting edge 19 gradually flattens outward from the cutting ring base 18 toward the tip of the cutting teeth 16.

[0048] The cutting angle (towards the cutting edge 13 of the cutting head) of the outer cutting tooth 16 or the outer cutting edge 19 is 55°, while the cutting angle of the inner cutting tooth 16 is 52.5°. Along the rotation direction of the impeller 3, the cutting angles are more gradual, at 20° externally and 10° internally. Each cutting tooth 16 extends outward from the cutting ring base 18 by at least 17 mm, with the inner cutting tooth 16 extending axially further away from the cutting ring base 18 than the outer cutting tooth 16. The cutting teeth 16 are also radially 'inclined', that is, gradually leveling off towards the opening 17 at 37° externally and 33° internally relative to the disc-shaped cutting ring base 18. Other cutting angles and dimensions are also conceivable.

[0049] Figure 4 The left-hand half-open perspective view and the right-hand half-open top view show the closed double-channel impeller 3 and the cutting head 1 of the pump according to a preferred embodiment of the present invention. Furthermore, the cutting head 1 is not in... Figure 4 The impeller 3 shown is fixedly connected along the axial extension of the impeller to a position that is not in the same location. Figure 4 The cutting rings 2 shown in the figure work together. The cutting head 1 is designed as previously described with a cutting head base 8 having a plurality of cutting segments 11, each of which has a cutting head cutting edge 13 extending particularly axially to crush solids, wherein the cutting head cutting edge 13 extends radially away from the cutting head base 8.

[0050] In a typical manner, the disc-shaped impeller 3 has two spirally extending blades 23, which extend from the central impeller opening 25 toward the inlet edge 24 of the cutting head 1 to the radial outer edge of the impeller. Figure 4 This is especially evident on the right side. The blade 23 is axially enclosed on one side by a radially extending support plate 26 on the motor side (which has a hub, not shown, for receiving the motor shaft of the pump), and on the other side by a radially extending cover plate 27 on the suction side, thus positioning the axially extending blade 23 between the support plate 26 and the cover plate 27, which are arranged parallel to each other. At the radially outer edge, the impeller 3 is radially open in a rectangular form in the side view between the support plate 26, the cover plate 27, and two adjacent blades 23.

[0051] For example, especially from Figure 4 As seen on the left, the cutting edge 13 of the cutting head is arranged spaced apart from the inlet edge 24. Furthermore, the inlet edge 24 is configured to be radially spaced outward from the inner edge of the impeller opening 25. Additionally, the cutting edge 13 of the cutting head is arranged radially ahead of the inlet edge 24 in the rotational direction of the impeller 3, as shown in… Figure 4 As shown on the right by angle α. In other words, the inlet edge 24 of the impeller 3 and the cutting edge 13 of the cutting head are not on the same radial line. Angle α is, for example, ≤2.5°, 5°, or 10°. The cutting edge 13 of the cutting head and the inlet edge 24 extend parallel to each other.

[0052] Here, two blades 23 are provided as previously implemented, and the cutting head 1, guided through the impeller opening 25, has four cutting edges 13. However, only the cutting edge 13 of the four cutting edges 13 that is not shortened 11 interacts with the blades 23. In the axial direction, the shortened cutting segment 11 is positioned in front of the blades 23 on the suction side, so the cutting edge 13 of the shortened cutting segment 11 does not interact with the blades 23. In an alternative design, for example, with eight cutting segments 11, the impeller 3 conveniently has four blades 23. For radial sealing of the impeller 3, a cylindrical sealing gap (not shown) is provided between the suction side 5 of the impeller 3 and the pump housing 4. An additional seal is designed in which the cutting ring 2 at least partially surrounds the impeller 3 to form a conical sealing gap.

[0053] The described embodiments are merely examples, and these examples can be modified and / or supplemented in various ways within the scope of the claims. Each feature used to illustrate a particular embodiment can be used independently or in combination with other features in any other embodiment. Each feature used to illustrate an embodiment of a certain category can also be applied accordingly to embodiments of another category.

[0054] List of reference numerals Cutting head 1 Cutting ring 2 Impeller 3 Pump housing 4 Inhalation side 5 Cutting head bolt 6 Cutting ring bolt 7 Cutting head base 8 Hole 9 outer periphery 10 Cutting segment 11 Liquid inlet side 12 Cutting head cuts edge 13 Side 14 Joint 15 Cutting teeth 16 Opening 17 Cutting ring matrix 18 Cut edge 19 Material recess 20 21 Recesses Depression 22 Leaf 23 Entrance edge 24 Impeller opening 25 26 bearing plates Cover plate 27

Claims

1. A pump having a pump housing (4) and components arranged in the pump housing (4), in, The components include a cutter head (1) and an impeller (3) for a pump carrying a liquid containing solids. The cutting head (1) is fixedly connected to the impeller (3) on the axial extension of the impeller to work together with the cutting ring (2), and the cutting head has a cutting head base (8) with multiple cutting segments (11), each cutting segment having a cutting edge (13) for crushing the solid, the cutting edge (13) extending radially away from the cutting head base (8). The impeller (3) has a plurality of blades (23) having an inlet edge (24) that is spaced apart from and extends substantially parallel to the cutting edge (13) of the cutting head. The cutting edge (13) of the cutting head is arranged radially in front of the inlet edge (24) in the rotational direction of the impeller (3). At least two of the cutting edges (13) of the cutting head have axial extensions of different lengths; the cutting edge (13) with the longer axial extension is arranged at least partially at the same axial height as the inlet edge (24); and, when viewed axially, the cutting edge (13) with the shorter axial extension does not reach the blade (23). In the rotational direction toward the cutting head (1), the cutting segment (11) extends concavely radially away from the cutting head base (8) to the corresponding cutting head cutting edge (13); in the rotational direction away from the cutting head (1), the cutting segment (11) extends linearly radially away from the cutting head base (8) to the cutting head cutting edge (13). In order to provide radial sealing for the impeller (3), a cylindrical sealing gap is provided between the pump suction side (5) and the pump housing (4); The pump also has a cutting ring (2) fixedly disposed on the pump, and for radial sealing, the cutting ring (2) at least partially surrounds the impeller (3) to form a conical sealing gap; The cutting ring (2) has a plurality of cutting teeth (16) that work together with the cutting edge (13) of the cutting head to crush the obtained solid. The cutting teeth (16) include cutting teeth (16) that extend axially inward toward the impeller (3) away from the cutting ring base (18) into the pump housing (4) and cutting teeth (16) that extend axially outward toward the suction side (5) from the pump housing (4).

2. The pump according to claim 1, wherein the cutting edge (13) of the cutting head is arranged in front of the inlet edge (24) at an angle α ≥ 1.5°, 2.5°, 5° or 10°.

3. The pump according to claim 1, wherein the impeller (3) has an impeller opening (25), the cutting head (1) is arranged in the impeller opening, and the inlet edge (24) is arranged to be radially spaced outward from the edge of the impeller opening (25).

4. The pump according to any one of claims 1 to 3, wherein the number of cutting edges (13) of the cutting head is equal to, unequal to, or twice the number of blades (23) and / or inlet edges (24).

5. The pump according to any one of claims 1 to 3, wherein the impeller (3) has a bearing disk (26) with a hub for receiving the motor shaft of the pump on the motor side and a cover disk (27) on the suction side, and the blades (23) are disposed between the bearing disk (26) and the cover disk (27).

6. The pump according to any one of claims 1 to 3, wherein the cutting edge (13) of the cutting head having a longer axial extension is arranged to be spaced apart from the inlet edge (24).

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