Cutting rings for pumps with liquids laden with solids

Abstract

The subject of the invention is a cutting ring (2) for a pump for a liquid laden with solids, the cutting ring having a cutting ring base (18) which forms an opening (17) for interaction with a cutting head (1), the cutting ring (2) being connected to the pump in a fixed position in the axial extension of the impeller (3) of the pump, wherein a plurality of cutting teeth (16) are arranged around the opening (17) on the cutting ring base (18), the cutting teeth having corresponding at least outer cutting edges (19) which are oriented away from the impeller (3) towards the suction side (5) of the pump, the cutting teeth (16) extending axially outwards away from the cutting ring base (18) at least towards the suction side (5), and a radially outwardly extending material recess (20) is introduced into at least the outwardly extending cutting teeth (16), and / or a radially outwardly extending pocket-shaped axial depression (22) is introduced into the cutting ring base (18) in a recess (21) between two at least outwardly extending cutting teeth (16).

Description

Technical Field

[0001] The invention relates to a cutting ring for a pump for a liquid laden with solids, the cutting ring having a cutting ring base body with an opening formed therein for interaction with a cutting head, the cutting ring being connected to the pump in a fixed position in the axial extension of the impeller of the pump, wherein a plurality of cutting teeth are arranged around the opening on the cutting ring, the cutting teeth having corresponding at least outer cutting edges oriented away from the impeller in the direction towards the suction side of the pump, and the cutting teeth extending axially outwards away from the cutting ring base body at least in the direction towards the suction side. Background Art

[0002] Solid mixtures in liquids, such as sewage, can clog pumps or pipes. To prevent such clogging, so-called cutting devices are used, which are located in front of the suction area of ​​the pump to break up the solids contained in the liquid.

[0003] The cutting devices known from the prior art usually have a fixed part, called a cutting surface or cutting element, and a rotating part, called a cutting head. Depending on the field of application of the cutting device, a circular, conical or cylindrical cutting surface can be used. The cutting surface (also called a cutting screen) has openings through which the liquid flows to the impeller of the pump. In the case of a flat or conical configuration of the cutting surface, it is called a cutting plate. A cylindrical configuration of the cutting surface is called a cutting ring.

[0004] Although the cutting effect of such cutting devices is very good in any case in the new state, the cutting devices themselves can become clogged, become blocked by solids or solids can get stuck in front of the suction area of ​​the pump, thereby blocking the suction area. In addition, cutting devices connected upstream of the pump usually have a negative impact on the efficiency and characteristic curve of the pump due to their influence on the flow rate flowing into the pump. Summary of the invention

[0005] Based on this situation, the object of the present invention is to provide a cutting ring for a pump for a liquid laden with solids, which cutting ring is safer in operation and reduces maintenance effort compared to the solutions known from the prior art and at the same time allows a high hydraulic efficiency of the pump.

[0006] Accordingly, the object is achieved by a cutting ring for a pump of a liquid laden with solids, the cutting ring having a cutting ring base body with an opening for interaction with a cutting head, the cutting ring being connected to the pump in a fixed position in the axial extension of the impeller of the pump, wherein

[0007] A plurality of cutting teeth are arranged around the opening on the cutting ring base body, the cutting teeth having respective inner cutting edges oriented axially preferably in the direction of the impeller and at least outer cutting edges oriented away from the impeller in the direction of the suction side of the pump, the cutting teeth preferably extending partially inwards in the direction of the impeller and partially axially outwards away from the cutting ring base body at least in the direction of the suction side, and

[0008] A radially outwardly extending material recess is introduced at least in each of these outwardly extending cutting teeth, and / or

[0009] In the recess between two at least outwardly extending cutting teeth, a pocket-shaped axial depression extending radially outward is introduced into the cutting ring basic body.

[0010] The key point of the proposed solution is to provide a material recess extending radially outward and / or an axial recess extending radially outward. Through these measures, solids that may be attached to the outer diameter of the cutting head and rotate during operation are subjected to cutting action on each axial plane of the cutting device composed of the cutting head and the cutting ring. In particular, the cutting surface is reduced by the material recess, thereby reducing friction, so that the required torque is less and the pump can be operated more reliably during startup and normal operation. This penetration of the cutting edge is achieved in particular by an axial recess extending externally, which is preferably designed in a bag-like manner and is introduced radially outward into the cutting ring matrix. The pocket is preferably configured between the cutting teeth and in the form of an axial recess. During operation, the cutting head can make the cutting edge of the rotating cutting head sweep over the cutting edge of the fixed cutting ring on the cylindrical outer circumference. In summary, a better and unobstructed inlet into the pump and a higher filtering effect are achieved by the proposed cutting ring.

[0011] A pump is generally a fluid machine that uses rotational motion and dynamic forces to transport a medium, mainly a liquid. Preferably, the pump is designed as a rotary pump. In a rotary pump, in addition to the tangential acceleration of the medium, the liquid, the centrifugal force generated in the radial flow is used for transport, so such pumps are also called centrifugal pumps. Preferably, the pump can be used in hydraulic installations of buildings, for example as a sewage pump.

[0012] During normal operation of the pump, the housing of the motor of the pump can be arranged above the pump housing, in which an impeller driven by the motor via a motor shaft is arranged to convey the fluid, wherein the motor housing is connected to the pump housing in a fixed position and / or can be designed as an integral unit. Preferably, the motor shaft extends inwardly from the motor housing into the pump housing on the drive side, and / or the impeller is connected to the motor shaft in a fixed position on the drive side.

[0013] The liquid preferably comprises water or another liquid medium, such as sewage. The liquid may comprise solids, such as any kind of pollutants, in particular excrement, sediment, sludge, sand, or even smaller pieces of wood, brush cuttings, textiles, rags or the like. Preferably, the motor housing and / or the pump housing are made of metal, in particular cast iron or profiled stainless steel, and / or of plastic.

[0014] The cutting ring base is preferably annular and / or made of metal, especially hard metal. The cutting head can be placed in an opening that is especially circular, so that the cutting edge of the cutting head can work together with the cutting edge of the cutting ring to crush the solid by rotating the cutting head. Preferably, a plurality of cutting teeth are provided, which have corresponding inner cutting edges oriented axially in the direction of the impeller and / or outer cutting edges oriented away from the impeller in the direction of the suction side of the pump, wherein the cutting teeth partially extend axially outward away from the cutting ring base in the direction of the impeller and partially at least in the direction of the suction side. The cutting teeth are preferably grouped around the opening in a cylindrical shape. The material recess and / or depression can be subsequently processed, for example by milling, or introduced during the manufacturing process of the cutting ring, for example by means of a correspondingly designed casting mold. Preferably, the inner diameter in the area of ​​the material recess is larger than the inner diameter in the area where the material recess is not provided. Preferably, the cutting edge is designed to have no material recess. Further preferably, the contour of the material recess is particularly parallel to the contour of the cutting edge. This results in a uniformly wide and therefore also uniformly stable cutting surface. Furthermore, a cutting ring interface can be provided on the inner side of the cutting ring, which transitions from the cutting ring base body into the inner cutting tooth in an axially narrowing manner. Preferably, a material recess extending radially outwards is introduced in all cutting teeth and / or an axial depression extending radially outwards is introduced in each of the recesses.

[0015] According to a preferred development, the cutting ring has a material recess which is arranged behind the cutting edge in the direction of rotation of the impeller. Preferably, the cutting edge is not formed with any material recess and is thus correspondingly stable and resistant even against larger solids. On the other hand, the material recess in the region of the cutting teeth behind the cutting edge in the direction of rotation allows a material-optimized and therefore cost-effective design of the cutting teeth.

[0016] According to another advantageous development, inner and outer cutting teeth are provided, and the outer cutting edge of the recess between two outwardly extending cutting teeth overlaps axially with the inner cutting edge of the recess between two inwardly extending inner cutting teeth. In such a design, no radially circumferential joints are formed on the cutting surface of the cutting ring formed by the cutting edges and not interrupted by the cutting edges. The solid body attached to the outer diameter of the cutting head and rotating therewith during operation is thus subjected to a cutting action in every axial plane of the cutting device formed by the cutting ring and the cutting head.

[0017] According to another preferred improvement, inner cutting teeth and outer cutting teeth are provided, and the inner cutting edge and the outer cutting edge extend axially in a wavy or sinusoidal manner around the opening and / or the cutting ring base body is flattened radially outward in the recess. To this end, the inner cutting edge and the outer cutting edge preferably extend inwardly and outwardly, respectively, in the normal direction of the cutting ring base body. Preferably, each recess corresponds axially to a cutting tooth and / or recess arranged oppositely on the cutting ring base body, so that, for example, recesses and / or recesses are arranged internally on the cutting ring base body, while the cutting teeth extend externally. Preferably, the cutting ring base body is flattened radially outwardly in a recess on one side, which is enclosed between two adjacent cutting teeth on this side.

[0018] According to another advantageous refinement, inner cutting teeth and outer cutting teeth are provided and, in the axial extension direction, an inner cutting edge and an outer cutting edge are respectively provided around the opening between the tip of the outer cutting tooth and the tip of the inner cutting tooth. The opening can be surrounded by the cutting edge all around. Preferably, the inner cutting teeth extend axially in the installed state until they reach the cylindrical joint on the cutting head.

[0019] According to another preferred improvement, the slope of the cutting edge gradually flattens outwards from the cutting ring base toward the tip of the cutting tooth in the direction of rotation of the impeller. In other words, the cutting teeth, especially those on the outside, are preferably designed so that the cutting angle always flattens outwards. Large particles of solids can thus slide off again unhindered, although they will be subjected to a certain cutting action at the end of the tooth. Smaller or pre-crushed solids, on the other hand, penetrate deeper into the cutting device formed by the cutting ring and the cutting head and are reliably crushed by the increased cutting angle, so that they pass through the cutting device in the direction of the impeller. The inner cutting teeth and the outer cutting teeth can have the same or different cutting angles.

[0020] According to another advantageous refinement, inner and outer cutting teeth are provided, and two, three, four, six or eight cutting teeth are provided, which are oriented alternately outwardly and inwardly. More cutting teeth can also be provided. Preferably, the number of outwardly directed cutting teeth corresponds to the number of cutting segments of the cutting device extending in this region, but other ratios are also possible.

[0021] According to another preferred improvement, the cutting ring base is designed to be disc-shaped and the cutting teeth extend axially away from the base. Preferably, the cutting ring is made of metal, in particular hard metal. The cutting edge can be implemented in a reinforced manner. It is also conceivable that the cutting edge and / or the cutting teeth are designed to be replaceable so that they can be replaced after wear.

[0022] According to another advantageous improvement, the inclination of the cutting edge in the direction of rotation of the impeller is steeper than the inclination in the direction opposite to the direction of rotation, so that the inclination of the cutting edge cooperating with the cutting head is gentler. In the direction of rotation of the impeller, the inclination of the cutting edge is preferably 20° on the outside and 10° on the inside. The inclination and cutting angle of the outer cutting edge are preferably 55° in the direction opposite to the direction of rotation, i.e. on the side cooperating with the cutting head, while the cutting angle of the inner cutting edge is preferably 52.5°. In the radial side view, each cutting tooth is preferably designed in a triangular shape. Preferably, each cutting tooth protrudes outward by at least 17 mm. The cutting teeth are also radially 'inclined', for example gradually sloping towards the opening at 37° on the outside and 33° on the inside relative to the disc-shaped cutting ring base. According to another preferred improvement, the inner cutting teeth extend axially farther away from the cutting ring base than the outer cutting teeth.

[0023] The objects of the invention are also achieved by a pump having a cutting ring as described above and a cutting head connected to an impeller in a rotationally fixed manner, the cutting head having a plurality of cutting head cutting edges which cooperate with the cutting edges to comminute captured solids.

[0024] Such a pump allows a better flow in the inlet of the impeller, thereby achieving a higher pump characteristic curve, since the disturbance of the flow between the blades or the blade channels formed by these blades is reduced compared to the designs known from the prior art. Due to the proposed cutting ring, solid bodies that may adhere to the outer diameter of the cutting head and rotate therewith during operation are subjected to a cutting action in each axial plane of the cutting device, thus achieving a better cutting result and a lower risk of clogging. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be explained in detail below by means of preferred embodiments with reference to the accompanying drawings.

[0026] In the attached picture:

[0027] Figure 1 A pump according to a preferred embodiment of the present invention is shown in a partial cross-sectional view.

[0028] Figure 2 The cutting head of a pump according to a preferred embodiment of the present invention is shown in two perspective views,

[0029] Figure 3 A cutting ring of a pump according to a preferred embodiment of the invention is shown in two perspective views (above) and in a partial cross-sectional view (below), and

[0030] Figure 4 The impeller and the cutting head of a pump according to a preferred embodiment of the invention are shown in a perspective view (left) and in a top view (right). DETAILED DESCRIPTION

[0031] Figure 1 A pump according to a preferred embodiment of the invention is shown in a partial cross-sectional view. The pump (embodied as a sewage submersible pump) has a cutting device connected upstream of the impeller 3, which comprises Figures 2 to 4 . The cutting head 1, cutting ring 2 and impeller 3 of the pump 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 the description below. Similar contents apply to the cutting ring 2 and the impeller 3. In this regard, when, for example, the cutting ring 2 is designed as described below, the cutting head 1 does not have to be designed as described below, but this is completely feasible.

[0032] Figure 1 The partial sectional view of FIG. 4 shows a part of the pump housing 4 of the pump, above which during normal operation of the pump a housing (not shown) for the motor of the pump is arranged. The motor drives an impeller 3 via a motor shaft (not shown), by means of which a liquid laden with solids can be sucked in from a suction side 5 designed below the pump housing 4. In this connection, the terms "axial" and "radial" used hereinafter each relate to the axial extension of the motor shaft.

[0033] The cutting head 1 is connected to the impeller 3 in a fixed manner, in particular in a force-fitting and / or form-fitting manner, by means of a cutting head screw 6 and rotates accordingly with the impeller 3 during operation of the pump. In contrast, the cylindrical cutting ring 2 surrounding the cutting head 1 is connected to the pump housing 4 in a fixed manner by means of a plurality of cutting ring screws 7. A radial seal is arranged between the cutting ring 2 and the impeller 3. The cutting head 1 extends into the suction side 5 so that the sucked liquid first flows from the suction side 5 through the gap arranged between the cutting head 1 and the cutting ring 2 in order to be subsequently conveyed through the impeller 3. Due to the rotational movement of the cutting head 1 relative to the cutting ring 2, the solids contained in the liquid are comminuted before reaching the impeller 3.

[0034] Figure 2 A cutting head 1 of a pump according to a preferred embodiment of the invention is shown in two perspective views. The left side shows the cutting head 1 in a perspective top view from the suction side 5, while the right side shows the cutting head 1 in a perspective top view from the side assigned to the impeller 3. The cutting head 1 has a cylindrical, rotationally symmetrical cutting head base body 8 made of metal, through which a hole 9 for receiving a cutting head bolt 6 for fastening to the impeller 3 extends in the axial direction.

[0035] Four cutting segments 11 are arranged at regular intervals on the outer circumferential surface 10 of the cutting head base body 8, and these cutting segments are designed integrally with the cutting head base body 8. The cutting segments 11 extend radially away from the cutting head base body 8. In addition, all the cutting segments 11 extend axially from the liquid inlet side 12 of the suction side 5 of the cutting head 1 opposite to the impeller 3 in the direction of the impeller 3 and thereby form an axially extending cutting head cutting edge 13.

[0036] In the left figure, the cutting segments 11 or their cutting head cutting edges 13 arranged oppositely at about 180° extend equally in the axial direction, i.e., substantially extend from the liquid inlet side 12 of the suction side 5 of the cutting head 1 to the opposite side 14 facing the impeller 3, while the two cutting segments 11 or their cutting head cutting edges 13 arranged therebetween at a spacing of 90° do not extend axially from the liquid inlet side 12 to the side 14. In other words, the two cutting head cutting edges 13 have axial extensions of different lengths relative to the other two cutting head cutting edges 13, because the first portion of the cutting head 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 of the cutting head cutting edge 13 extends from the liquid inlet side 12 only over a portion of the entire axial extension of the cutting head 1.

[0037] In other words, the second part of the cutting segment 11 is shortened by about half relative to the first part, wherein the oppositely arranged cutting segments 11 are correspondingly implemented to be identical. The shortened part of the cutting segment 11 on the axial extension is implemented without the cutting head cutting edge 13. The shortened cutting segment 11 has a constant radial diameter until about half of the axial extension of the cutting head 1, and then gradually narrows in a teardrop-like manner in its diameter toward the side 14 facing the impeller 3. The cutting head 1 has a surrounding cylindrical joint 15 at its axial side 14 facing the impeller 3, which is implemented in one piece with the cutting head base 8 and ends flush with the cutting head cutting edge 13 in terms of its radial outer diameter. The joint 15 gradually narrows in its diameter from the side 14 toward the liquid inlet side 12 in a manner that uniformly transitions into the cutting head base 8.

[0038] In the direction of rotation toward the cutting head 1, the cutting segment 11 extends concavely radially away from the cutting head base body 8 to the corresponding cutting head cutting edge 13. In contrast, in the direction of rotation away from the cutting head 1, the extended cutting segment 11 extends linearly radially away from the cutting head base body 8 to the cutting head cutting edge 13. Similar contents apply to the teardrop-shaped narrowing of the shortened cutting segment 11.

[0039] For further flow optimization, the cutting segments 11 and the cutting head cutting edge 13 are inclined at the liquid inlet side 12 of the cutting head 1 opposite to the impeller 3, as can be seen from Figure 2 In order to comminute the collected solids, the above-described cutting head 1 can interact with its cutting head cutting edge 13 with a cutting ring 2 having a plurality of cutting teeth 16 which is fixedly arranged on the pump as described below.

[0040] Figure 3 A cutting ring 2 of a pump according to a preferred embodiment of the invention is shown in two perspective views (above) and in a partial cross-sectional view (below). The cutting ring 2 has an annular cutting ring base body 18 forming an opening 17. Figure 1 In the mounted state shown in FIG, the cutting head 1 is guided through the opening 17. As described above, the cutting ring 2 is fixedly secured to the pump housing 4 of the pump in the axial extension of the impeller 3 by means of three cutting ring bolts 7 distributed around the opening 17.

[0041] A plurality of cutting teeth 16 are arranged at regular intervals around the opening 17 on a rotationally symmetrical cutting ring base 18, which have corresponding inner cutting edges 19 oriented axially in the direction of the impeller 3 and outer cutting edges 19 oriented axially away from the impeller 3 in the direction of the suction side 5 of the pump, wherein the cutting edges 19 interact with the cutting head cutting edge 13 of the cutting head when the cutting head 1 rotates.

[0042] The corresponding three cutting teeth 16 extend axially inwardly into the pump housing 4 away from the cutting ring base body 18 in the direction of the impeller 3, and the corresponding three cutting teeth 16 extend outwardly from the pump housing 4 in the direction of the suction side 5, as shown in Figure 1 Similarly, four, eight, twelve or more cutting teeth 16 may be provided, the orientation of these cutting teeth being alternately outward and inward. In the axial extension direction, between the tip of the outer cutting tooth 16 and the tip of the inner cutting tooth 16, an inner cutting edge 19 and an outer cutting edge 19 are respectively designed around the opening 17.

[0043] The cutting teeth 16 extending outwardly are Figure 3 The lower cross-sectional view shows below the disk-shaped cutting ring base body 18 , while the inwardly extending cutting teeth 16 are shown above the cutting ring base body 18 in the cross-sectional view. Figure 3 The upper right perspective view corresponds to this representation and shows a view of the cutting ring 2 from the suction side 5 , while the upper left perspective view shows a view of the cutting ring 2 from the pump housing 4 .

[0044] At least in the outwardly extending cutting teeth 16, radially outwardly extending material recesses 20 are respectively introduced behind the cutting edge 19 in the direction of rotation of the impeller 3. Such material recesses 20 are also introduced in the inwardly extending cutting teeth 16. This means that the outer diameter of the cutting teeth 16, which extend in a wavy manner around the opening 17 or sinusoidally around the opening in a top view, is equal, while the inner diameter is increased in the region of the material recesses 20 relative to the region of the cutting teeth 16 without material recesses.

[0045] Alternatively or additionally, in the recesses 21 between at least two cutting teeth 16 extending outwards, a pocket-shaped axial depression 22 extending radially outwards is introduced into the cutting ring base body 18. In this case, a pocket-shaped axial depression 22 is introduced both in the recesses 21 between the cutting teeth 16 extending outwards and inwards. The depression 22 extends in a manner recessed radially outwards from the bottom of the recess, so that the cutting ring base body 18 is flattened radially outwards in the recess 21. The material recesses 20 and the recesses 21 are provided on all cutting teeth 16 or between them and can be produced by milling or by corresponding injection molding of the metallic cutting ring 2.

[0046] In particular, from Figure 3As can be seen in the figure below, the cutting edge 19 on the outside of the recess 21 between two outwardly extending cutting teeth 16 overlaps the cutting edge 19 on the inside of the recess 21 between two inwardly extending cutting teeth 16 in the axial direction. In this way, there is no radially circumferential joint that is not interrupted by the cutting edge 19 on the cutting surface of the cutting ring 2 formed by the cutting edge 19. In the direction of rotation of the impeller 3, the cutting angle of the cutting edge 19 gradually becomes gentler from the cutting ring base 18 outwardly toward the tip of the cutting tooth 16.

[0047] The cutting angle of the outer cutting teeth 16 or the outer cutting edge 19 (towards the cutting head cutting edge 13) is 55°, wherein the cutting angle of the inner cutting teeth 16 is 52.5° in contrast. In the direction of rotation of the impeller 3, the cutting angle is more gradual and is 20° on the outside and 10° on the inside. Each cutting tooth 16 protrudes outwards from the cutting ring base 18 by at least 17 mm, wherein the inner cutting teeth 16 extend axially further away from the cutting ring base 18 than the outer cutting teeth 16. The cutting teeth 16 are also radially 'inclined', i.e. they taper towards the opening 17 at 37° on the outside and 33° on the inside relative to the disc-shaped cutting ring base 18. Other cutting angles and dimensions are also conceivable.

[0048] Figure 4 The closed double-channel impeller 3 and the cutting head 1 of the pump according to the preferred embodiment of the present invention are shown in a half-open perspective view on the left and a half-open top view on the right. Figure 4 The impeller 3 shown in FIG. 1 is fixedly connected along the axial extension of the impeller to the impeller 3, which is also not shown in FIG. Figure 4 The cutting head 1 is designed as described above with a cutting head base body 8 having a plurality of cutting segments 11 which each have an axially extending cutting head cutting edge 13 for comminuting solids, wherein the cutting head cutting edge 13 extends radially away from the cutting head base body 8 .

[0049] According to the usual manner, the disk-shaped impeller 3 has two helically extending blades 23, which extend from an inlet edge 24 facing the cutting head 1 at a central impeller opening 25 to the radial outer edge of the impeller, as can be seen in FIG. Figure 4 The blades 23 are axially enclosed on the one hand by a radially extending carrier disk 26 on the motor side (the carrier disk has a hub (not shown) for receiving the motor shaft of the pump) and on the other hand by a radially extending cover disk 27 on the suction side, so that the axially extending blades 23 are arranged between the carrier disk 26 and the cover disk 27 arranged parallel to each other. At the radial outer edge, the impeller 3 is radially open in a rectangular form in a side view between the carrier disk 26, the cover disk 27 and two adjacent blades 23.

[0050] In particular, from Figure 4 As seen from the left, the cutting head cutting edge 13 is arranged spaced apart from the inlet edge 24. Furthermore, the inlet edge 24 is arranged spaced apart radially outwardly from the inner edge of the impeller opening 25. Furthermore, the cutting head cutting edge 13 is arranged radially in front of the inlet edge 24 in the direction of rotation of the impeller 3 and in particular radially overlaps with the inlet edge, as shown in FIG. Figure 4 The right side is shown by the angle α. In other words, the inlet edge 24 of the impeller 3 and the cutting head cutting edge 13 are not on a radial line. The angle α is, for example, ≤2.5°, 5° or 10° and in particular α≤2.5°, 5°, 10°, 15°, 20°, 30° or 45°. The cutting head cutting edge 13 and the inlet edge 24 extend parallel to each other. "Radial overlap" means, in particular, that the inlet edge is at least partially arranged at the same axial height as the cutting head cutting edge and / or is at least partially arranged in a common radial plane with the cutting head cutting edge. Preferably, the axial extension of the cutting head cutting edge is greater than the axial extension of the inlet edge.

[0051] Here, as previously implemented, two blades 23 are provided, while the cutting head 1 guided through the impeller opening 25 has four cutting head cutting edges 13. However, of these four cutting head cutting edges 13, only the cutting head cutting edges 13 of the cutting segments 11 that have not been shortened interact with the blades 23. In the axial direction, the shortened cutting segments 11 are arranged in front of the blades 23 on the suction side, so that the cutting head cutting edges 13 of the shortened cutting segments 11 do not drive with the blades 23. If, for example, in an alternative design with eight cutting segments 11, the impeller 3 conveniently has four blades 23. For the 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. A further seal is provided, in which the cutting ring 2 at least partially surrounds the impeller 3 to form a conical sealing gap.

[0052] The described embodiments are only examples, which can be modified and / or supplemented in various ways within the scope of the claims. Each feature used to illustrate a certain embodiment can be used in any other embodiment independently or in combination with other features. Each feature used to illustrate an embodiment of a certain category can also be used in another category of embodiments in a corresponding manner.

[0053] Reference numerals list

[0054] Cutting head 1

[0055] Cutting ring 2

[0056] Impeller 3

[0057] Pump housing 4

[0058] Suction side 5

[0059] Cutting head bolt 6

[0060] Cutting ring bolt 7

[0061] Cutting head base 8

[0062] Hole 9

[0063] Outer surface 10

[0064] Cutting segment 11

[0065] Liquid inlet side 12

[0066] Cutting head cutting edge 13

[0067] Side 14

[0068] Joint 15

[0069] Cutting teeth 16

[0070] Opening 17

[0071] Cutting ring base 18

[0072] Cutting edge 19

[0073] Material recess 20

[0074] Recess 21

[0075] Depression 22

[0076] Blade 23

[0077] Entrance edge 24

[0078] Impeller opening 25

[0079] Carrier plate 26

[0080] Cover plate 27

Claims

1. A pump for liquids laden with solids, comprising an impeller (3) and a cutting ring (2), wherein The cutting ring (2) has a cutting ring base (18) with an opening (17) for interaction with the cutting head (1), the cutting ring (2) being connected to the pump in a fixed position in the axial extension of the impeller (3) of the pump, The cutting ring base (18) comprises a plurality of inner cutting teeth (16) with inner cutting edges (19) and outer cutting teeth (16) with outer cutting edges (19), the outer cutting teeth (16) being oriented away from the impeller (3) in the direction towards the suction side (5) of the pump, the cutting teeth (16) being arranged on the cutting ring base (18) around the opening (17), The inner cutting teeth (16) and the outer cutting teeth (16) extend axially inwardly and outwardly from the cutting ring base (18) respectively, at least in the direction of the suction side (5). A material recess (20) extending radially outwards is introduced at least in the outer cutting teeth (16) extending outwards, the material recess (20) being arranged behind the cutting edge (19) in the direction of rotation of the impeller (3). In a recess (21) between two at least outwardly extending cutting teeth (16), a pocket-shaped axial depression (22) extending radially outward is introduced into the cutting ring base body (18), and The outer cutting edge (19) of the recess (21) between the two outer cutting teeth (16) overlaps the inner cutting edge (19) of the recess (21) between the two inner cutting teeth (16) in the axial direction.

2. A pump according to claim 1, wherein the inner cutting edge (19) and the outer cutting edge (19) extend axially in a wave-like or sinusoidal manner around the opening (17) and / or the cutting ring base (18) flattens radially outward in the recess (21).

3. A pump according to claim 1 or 2, wherein in the axial extension direction, an inner cutting edge (19) and an outer cutting edge (19) are correspondingly designed around the opening (17) between the tip of the outer cutting tooth (16) and the tip of the inner cutting tooth (16).

4. The pump according to claim 1 or 2, wherein in the rotation direction of the impeller (3), the slope of the cutting edge (19) gradually becomes gentler from the cutting ring base (18) outwardly toward the tip of the cutting tooth (16).

5. The pump according to claim 1 or 2, having four, six or eight cutting teeth (16) which are oriented alternately outwardly and inwardly.

6. The pump according to claim 1 or 2, wherein the cutting ring base body (18) is designed in a disk shape and the cutting teeth (16) extend axially away from the base of the cutting ring base body (18).

7. The pump according to claim 1 or 2, wherein the cutting angle of the cutting edge (19) in the rotation direction of the impeller (3) is shallower than the cutting angle in the direction opposite to the rotation direction.

8. The pump according to claim 1 or 2, wherein the inner cutting teeth (16) extend axially further away from the cutting ring base (18) than the outer cutting teeth (16).

9. A pump according to claim 1 or 2, having the cutting head (1) connected to the impeller (3) in a rotationally fixed manner, the cutting head (1) having a plurality of cutting head cutting edges (13), which act together with the cutting edge (19) of the cutting ring (2) to comminute the captured solids.

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