EP4108935B1 - Cutting ring for a pump for a liquid containing solids - Google Patents

Description

technical field

The invention relates to a cutting ring for liquid of a pump loaded with solids, with a cutting ring base body forming an opening for interaction with a cutting head, which cutting ring can be connected to the pump in a stationary manner in the axial extension of an impeller of the pump, wherein a plurality of cutting teeth with respective at least outer cutting edges oriented in the direction of a suction side of the pump away from the impeller are provided on the cutting ring around the opening, and the cutting teeth extend axially away from the cutting ring base body at least in the direction of the suction side to the outside.

Background of the invention

Admixtures of solids in liquids such as wastewater can clog pumps or pipes. To prevent such blockages, so-called cutting units are used, which are located in front of the suction area of the pumps in order to chop up the solids contained in the liquid.

Cutting devices known from the state of the art often have a fixed part, called a cutting surface or cutting element, and a rotating part, called a cutting head. Depending on the application of the cutting device, circular, conical or cylindrical cutting surfaces can be used. The cutting surfaces, also called cutting screens, have openings through which the liquid flows to an impeller of the pump. If the cutting surface is flat or conical, it is called a cutting plate. A cylindrical cutting surface is called a cutting ring.

CN 210715160 U describes a cutting pump, in particular a radial gap adjustable cutting pump.

CN 208236728 U describes a water installation of sewage pumps, which belongs to the technical area of pumping equipment.

WO 2016/201436 A1 describes one or more techniques and/or systems for a cutting/grinding system that can be engaged with a pump.

While the cutting effect of such cutters is good when new, the cutters themselves can become clogged, blocked by solids, or solids can become stuck in front of the pump's suction area, thereby blocking the suction area. In addition, a cutter installed upstream of the pump usually has a negative effect on the pump's efficiency and characteristic curve because it affects the inflow into the pump.

Description of the Invention

Based on this situation, it is an object of the present invention to provide a cutting ring for liquids of a pump loaded with solids, which is more reliable in operation than the solutions known from the prior art, reduces maintenance costs and at the same time enables a high hydraulic efficiency of the pump.

The object of the invention is solved by the features of the independent claim. Advantageous embodiments are specified in the subclaims.

• an dem Schneidringgrundkörper um die Öffnung herum eine Mehrzahl Schneidzähne mit jeweiligen vorzugsweise inneren axial in Richtung des Laufrades und wenigstens äußeren in Richtung einer Saugseite der Pumpe weg von dem Laufrad orientierten Schneidkanten vorgesehen sind, sich die Schneidzähne von dem Schneidringgrundkörper axial weg vorzugsweise teils in Richtung des Laufrades nach innen und teils wenigstens in Richtung der Saugseite nach außen erstrecken,
• wenigstens in den sich nach außen erstreckenden Schneidzähnen jeweils eine sich radial nach außen erstreckende Materialaussparung eingebracht ist, und
• in einem Tal zwischen zwei sich wenigstens nach außen erstreckenden Schneidzähnen eine sich radial nach außen erstreckende axiale Vertiefung in den Schneidringgrundkörper eingebracht ist.

Accordingly, the object is achieved by a pump for liquids loaded with solids, with an impeller and a cutting ring, wherein the cutting ring has a cutting ring base body forming an opening for interaction with a cutting head, and is fixedly connected to the pump in the axial extension of an impeller of the pump, wherein

• a plurality of cutting teeth are provided on the cutting ring base body around the opening, each with preferably inner cutting edges oriented axially in the direction of the impeller and at least outer cutting edges oriented in the direction of a suction side of the pump away from the impeller, the cutting teeth extending from the cutting ring base body extend axially away preferably partly inwards towards the impeller and partly at least outwards towards the suction side,
• at least in the outwardly extending cutting teeth a radially outwardly extending material recess is introduced, and
• in a valley between two cutting teeth extending at least outwards, a radially outwardly extending axial recess is introduced into the cutting ring base body.

A key point of the proposed solution is to provide a material recess that extends radially outwards and to provide a radially outwards extending axial recess. Through these measures, solids that may become stuck to the outer diameter of the cutting head and rotate during operation experience a cutting effect in every axial plane of the cutting mechanism formed by the cutting head and cutting ring. In particular, the material recess reduces the cutting surface, which reduces friction, so that less torque is required and the pump can be operated more reliably both during start-up and during regular operation. This penetration of the cutting edges in particular is achieved by the preferably pocket-shaped axial recess that extends outwards and is introduced radially outwards into the cutting ring base body. The pockets are preferably formed between the cutting teeth and in the form of axial recesses. During operation, the cutting edges of the rotating cutting head can pass the cutting edges of the stationary cutting ring on a cylindrical peripheral surface. In summary, the proposed cutting ring achieves a better and unhindered inflow to the pump inlet and a higher filtering effect.

A pump is generally a fluid machine that uses a rotary motion and dynamic forces to convey mainly liquids as a medium. The pump is preferably designed as a centrifugal pump. In a centrifugal pump, in addition to a tangential acceleration of the liquid, the medium, centrifugal force occurring in radial flow is used for conveying, so that such pumps are also referred to as centrifugal pumps. The pump can preferably be used for a hydraulic system in a building, for example as a sewage pump.

During normal operation of the pump, a housing of a motor of the pump can be arranged above a pump housing in which the impeller driven by the motor via the motor shaft is provided for conveying the fluid, wherein the housing of the motor can be fixedly connected to the pump housing and/or designed as a single piece. Preferably, the motor shaft projects from the housing of the motor into the pump housing on a drive side and/or the impeller is fixedly connected to the motor shaft on the drive side.

The liquid preferably comprises water or another liquid medium such as waste water. The fluid can comprise solids such as impurities of any kind, in particular faeces, sediments, dirt, sand, or even smaller pieces of wood, brushwood, textiles or rags or the like. The housing of the motor and/or the pump housing is preferably made of metal, in particular cast iron or contoured stainless steel, and/or plastic.

The cutting ring base body is preferably ring-shaped and/or made of metal, in particular of a hard metal. The cutting head can be inserted into the opening, which is in particular circular, so that by rotating the cutting head, the cutting head cutting edges can interact with the cutting edges of the cutting ring to crush the solid material. The plurality of cutting teeth are preferably provided with respective inner cutting edges oriented axially in the direction of the impeller and/or outer cutting edges oriented in the direction of the suction side of the pump away from the impeller, wherein the cutting teeth extend axially away from the cutting ring base body, partly inwards in the direction of the impeller and partly outwards in the direction of the suction side. The cutting teeth are preferably grouped in a cylinder-like manner around the opening. The material recess and/or the depression can be incorporated subsequently, for example by milling, or can be introduced during the manufacture of the cutting ring, for example by means of a correspondingly designed mold. Preferably, an inner diameter in the area of the material recess is larger than in the area in which no material recess is provided. The cutting edges are preferably designed free of the material recess. Further preferably, a contour of the material recess follows, in particular, parallel to a contour of the cutting edge. This results in a uniformly wide and thus also uniformly stable cutting surface. Furthermore, a cutting ring collar can be provided on the inside of the cutting ring, which tapers axially from the cutting ring base body into the inner cutting teeth. Preferably, a material recess extending radially outwards is introduced in all cutting teeth, and/or an axial depression extending radially outwards is introduced in all valleys.

According to a preferred development, the material recess is provided behind the cutting edge in the direction of rotation of the impeller. The cutting edge is preferably formed without a material recess and is thus correspondingly stable and resistant even with regard to larger solids. On the other hand, the material recess in the area of the cutting tooth behind the cutting edge in the direction of rotation allows the cutting tooth material to be optimized and thus made cost-effective.

According to another advantageous development, inner and outer cutting teeth are provided and the outer cutting edge of a valley between two outwardly extending cutting teeth and the inner cutting edge of a valley between two inwardly extending cutting teeth overlap axially. In such a design, no radially encircling collar that is not interrupted by a cutting edge is formed on a cutting surface of the cutting ring formed by the cutting edges. Solids that adhere to the outer diameter of the cutting head and rotate during operation are thus subjected to a cutting effect in every axial plane of the cutting mechanism formed by the cutting ring and cutting head.

According to another preferred development, inner and outer cutting teeth are provided and the inner and outer cutting edges extend axially in a wave-like or sinusoidal manner around the opening and/or the cutting ring base body is flattened radially outwards in the valley. For this purpose, the inner and outer cutting edges preferably extend inwards and outwards in the direction of the normal of the cutting ring base body. Preferably, each valley corresponds axially to a cutting tooth and/or a recess provided oppositely on the cutting ring base body, so that, for example, a valley and/or a recess is provided on the inside of the cutting ring base body and a cutting tooth extends on the outside. Preferably, the Cutting ring base body flattened radially outwards on the side in the valley, at which the valley is enclosed between two adjacent cutting teeth.

According to another advantageous development, inner and outer cutting teeth are provided and the inner cutting edge and the outer cutting edge are formed in the axial extension between a tip of an outer cutting tooth and a tip of an inner cutting tooth around the opening. The opening can be surrounded by a cutting edge all the way around. The inner cutting teeth preferably extend axially over a cylindrical collar on the cutting head when installed.

According to another preferred development, a slope of the cutting edge flattens outwards from the cutting ring base body to a tip of the cutting tooth in the direction of rotation of the impeller. In other words, external cutting teeth in particular are preferably designed in such a way that the cutting angle becomes increasingly flatter towards the outside. Coarse solids therefore experience a certain cutting effect at the end of the teeth, but can slide off again unhindered. Smaller or sufficiently pre-shredded solids, on the other hand, penetrate deeper into the cutting mechanism formed by the cutting ring and cutting head and are reliably shredded by the steeper cutting angle and pass through the cutting mechanism in the direction of the impeller. Inner and outer cutting teeth can have the same or different cutting angles.

According to another advantageous development, inner and outer cutting teeth are provided and two, three, four, six or eight cutting teeth are provided, which are oriented alternately outwards and inwards. 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 mechanism extending in this area, although other ratios are also possible.

According to another preferred development, the cutting ring base body is designed like a disk and the cutting teeth extend axially away from the base surface. The cutting ring is preferably made of a metal, in particular a hard metal. The cutting edges can be reinforced. It is also conceivable that the cutting edges and/or the cutting teeth are designed to be replaceable so that they can be replaced once they have worn out.

According to another advantageous development, the slope of the cutting edge in the direction of rotation of the impeller is steeper than the slope against the direction of rotation, so that the slope of the cutting edge that interacts with the cutting head is flatter. In the direction of rotation of the impeller, the slope of the cutting edge is preferably 20° on the outside and 10° on the inside. The slope and the cutting angle of the outer cutting edges is against the direction of rotation, i.e. on the side that interacts with the cutting head, preferably 55°, while the cutting angle of the inner cutting edges is preferably 52.5°. In radial side view, each cutting tooth is preferably designed in a triangular manner. Each cutting tooth preferably protrudes at least 17 mm outwards. The cutting teeth can also be radially 'sharpened', for example flattened towards the opening at 37° on the outside and 33° on the inside compared to the disk-like cutting ring base body. According to another preferred development, the inner cutting tooth extends further axially away from the cutting ring base body than the outer cutting tooth.

Advantageously, the pump has a cutting head which is connected to the impeller in a rotationally fixed manner and has a plurality of cutting head teeth which cooperate with the cutting edges to crush the captured solid material.

Such a pump enables better flow in the inlet area of the impeller, which results in a higher pump characteristic curve, since disruption of the flow between the blades or the blade channels formed by them is reduced compared to designs known from the state of the art. The proposed cutting ring causes solids that adhere to the outer diameter of the cutting head and rotate during operation to experience a cutting effect in every axial plane of the cutting mechanism, so that a better cutting result and a lower risk of clogging are achieved.

Short description of the drawings

The invention is explained in more detail below with reference to the accompanying drawings using preferred embodiments.

Fig. 1

eine Pumpe in einer Teilschnittansicht gemäß einem bevorzugten Ausführungsbeispiel der Erfindung,

Fig. 2

einen Schneidkopf der Pumpe in zwei perspektivischen Ansichten gemäß dem bevorzugten Ausführungsbeispiel der Erfindung,

Fig. 3

einen Schneidring der Pumpe in zwei perspektivischen Ansichten (oben) sowie in einer Schnittansicht (unten) gemäß dem bevorzugten Ausführungsbeispiel der Erfindung, und

Fig. 4

ein Laufrad und den Schneidkopf der Pumpe in einer perspektivischen Ansicht (links) und in einer Draufsicht (rechts) gemäß dem bevorzugten Ausführungsbeispiel der Erfindung.

In the drawings show

Fig. 1

a pump in a partial sectional view according to a preferred embodiment of the invention,

Fig. 2

a cutting head of the pump in two perspective views according to the preferred embodiment of the invention,

Fig. 3

a cutting ring of the pump in two perspective views (above) and in a sectional view (below) according to the preferred embodiment of the invention, and

Fig. 4

an impeller and the cutting head of the pump in a perspective view (left) and in a plan view (right) according to the preferred embodiment of the invention.

Detailed description of the implementation examples

Fig. 1 shows a pump in a partial sectional view according to a preferred embodiment of the invention. The pump, designed as a sewage submersible motor pump, has a cutting mechanism upstream of an impeller 3 comprising a cutting head 1 and a cutting ring 2, which in Figs. 2 to 4 are shown. The cutting head 1 or 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 impeller 3 can be designed differently than described below.

The cutting head 1 does not have to be designed as described below, although this is certainly possible.

The partial sectional view of the Fig. 1 shows a part of a pump housing 4 of the pump, above which a housing (not shown) for a motor of the pump is provided during regular operation of the pump. The motor drives the impeller 3 via a motor shaft (not shown), through which liquid loaded with solids can be sucked in from a suction side 5 formed below the pump housing 4. In this respect, the terms axial and radial used below each refer to the axial extension of the motor shaft.

The cutting head 1 is fixedly connected to the impeller 3, 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. The cylinder-like cutting ring 2 enclosing the cutting head 1 is, in contrast, fixedly connected to the pump housing 4 by means of a plurality of cutting ring screws 7. A radial seal is provided between the cutting ring 2 and the impeller 3. The cutting head 1 projects into the suction side 5, so that liquid sucked in from the suction side 5 first flows through a gap provided between the cutting head 1 and the cutting ring 2, and is then conveyed through the impeller 3. The rotary movement of the cutting head 1 relative to the cutting ring 2 causes solids contained in the liquid to be broken down before they reach the impeller 3.

Fig. 2 shows the cutting head 1 of the pump in two perspective views according to the preferred embodiment of the invention. On the left, the cutting head 1 is shown in a perspective top view from the suction side 5, while on the right the cutting head 1 is shown in a perspective top view from the side associated with the impeller 3. The cutting head 1 has a cylinder-like, rotationally symmetrical cutting head base body 8 made of metal, through which a bore 9 extends axially for receiving the cutting head screw 6 for fastening to the impeller 3.

Four cutting segments 11 arranged at regular intervals are provided on the peripheral surface 10 of the cutting head base body 8 and are designed as one piece with the cutting head base body 8. The cutting segments 11 each extend radially away from the cutting head base body 8. Furthermore, all cutting head base bodies 8 extend axially in the direction of the impeller 3 from a liquid inlet side 12 of the cutting head 1 opposite the impeller 3 and facing the suction side 5, thus forming axially extending cutting head cutting edges 13.

While the cutting segments 11 or their cutting head cutting edges 13 arranged on the left and right at 180° opposite one another in the left figure extend axially over the same length, namely from the liquid inlet side 12 of the cutting head 1 facing the suction side 5 to essentially the opposite side 14 facing the impeller 3, the two cutting segments 11 or their cutting head cutting edges 13 arranged at a distance of 90° between them do not extend axially from the liquid inlet side 12 to the side 14. In other words, two cutting head cutting edges 13 have a different axial extension compared to the other two cutting head cutting edges 13, since a first part of the cutting head cutting edges 13 extends from the liquid inlet side 14 essentially or over the entire axial extension of the cutting head 1 and a second part of the Cutting head cutting edges 13 extend from the liquid inlet side 14 only over a part of the total axial extension of the cutting head 1.

In other words, the second part of the cutting segments 11 is shortened by about half compared to the first part, whereby the cutting segments 11 arranged opposite one another are each identical. The shortened part of the cutting segments 11 of the axial extension is free of cutting head cutting edges 13. The shortened cutting segments 11 have a constant radial diameter up to about half of the axial extension of the cutting head 1 and then taper in a drop-shaped manner towards the side 14 facing the impeller 3. On its side 14 axially facing the impeller 3, the cutting head 1 has a circumferential, cylindrical collar 15 which is designed in one piece with the cutting head base body 8 and is flush with the cutting head cutting edges 13 in terms of its radial outer diameter. The collar 15 tapers its diameter gradually increases from side 14 towards the liquid inlet side 12 into the cutting head base body 8.

Facing the direction of rotation of the cutting head 1, the cutting segments 11 extend concavely radially away from the cutting head base body 8 towards the respective cutting head cutting edge 13. In contrast, facing away from the direction of rotation of the cutting head 1, the cutting segments 11 extend linearly radially away from the cutting head base body 8 towards the cutting head cutting edge 13. The same applies to the drop-shaped taper of the shortened cutting segments 11.

For further flow optimization, the cutting segments 11 and the cutting head cutting edges 13 are beveled on the liquid inlet side 12 of the cutting head 1 opposite the impeller 3, as can be seen from Fig. 2 can be seen. To crush the captured solid material, the above-described cutting head 1 with its cutting head cutting edges 13 can interact with the cutting ring 2 provided in a fixed position on the pump and having a plurality of cutting teeth 16 as described below.

Fig. 3 shows a cutting ring 2 of the pump in two perspective views (above) and in a sectional view (below) according to the preferred embodiment of the invention. The cutting ring 2 has a ring-like cutting ring base body 18 forming an opening 17. In Fig. 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 in place to the pump housing 4 of the pump by means of three cutting ring screws 7 grouped around the opening 17 in the axial extension of the impeller 3.

At regular intervals on the rotationally symmetrical cutting ring base body 18 around the opening 17, a plurality of cutting teeth 16 with respective inner cutting edges 19 oriented axially in the direction of the impeller 3 and outer cutting edges 19 oriented in the direction of the suction side 5 of the pump away from the impeller 3 are provided, wherein the cutting edges 19 interact with the cutting head cutting edges 13 of the cutting head 1 when the cutting head 1 rotates.

Three cutting teeth 16 extend axially away from the cutting ring base body 18 in the direction of the impeller 3 inwards into the pump housing 4 and three cutting teeth 16 extend in the direction of the suction side 5 outwards from the pump housing 4, as in Fig. 1 Four, eight, twelve or more cutting teeth 16 can also be provided, which are oriented alternately outwards and inwards. In the axial extension, an inner cutting edge 19 and an outer cutting edge 17 are formed around the opening 17 between a tip of an outer cutting tooth 16 and a tip of an inner cutting tooth 16. The outwardly extending cutting teeth 16 are shown in the sectional view below in the Fig. 3 below the disk-like cutting ring base body 18, while the inwardly extending cutting teeth 16 are shown in the sectional view above the cutting ring base body 18. The perspective illustration at the top right in Fig. 3 corresponds to this illustration and shows the view of the cutting ring 2 seen from the suction side 5, while the perspective illustration at the top left shows the view of the cutting ring 2 seen from the pump housing 4. At least in the outwardly extending cutting teeth 16, a radially outwardly extending material recess 20 is made in the direction of rotation of the impeller 4 behind the cutting edge 19. Such a material recess 20 is also made in the inwardly extending cutting teeth 16. This means that the outer diameter of the cutting teeth 16, which extend in a ring shape around the opening 17 in a wave-like or sinusoidal manner around the opening in plan view, is the same, while the inner diameter in the area of the material recess 20 is larger than an area of the cutting teeth 16 without a material recess.

In addition, a pocket-like axial recess 22 extending radially outward is made in the cutting ring base body 18 in a valley 21 between at least two outwardly extending cutting teeth 16. In the present case, pocket-like axial recesses 22 are made in both the valleys 21 between the outwardly and the inwardly extending cutting teeth 16. The recesses 22 extend from the valley bottom radially outward, deepening so that the cutting ring base body 18 is flattened radially outward in the valley 21. The material recesses 20 and valleys 21 are provided on all cutting teeth 16 or between them and can be produced by milling or by a corresponding casting mold of a metal cutting ring 2.

As can be seen particularly from the figure below in Fig. 3 As can be seen, the outer cutting edge 19 of a valley 21 between two outwardly extending cutting teeth 16 and the inner cutting edge 19 of a valley 21 between two inwardly extending cutting teeth 16 overlap in the axial direction. In this way, there is no radially circumferential collar on a cutting surface of the cutting ring 2 formed by the cutting edges 19 that is not interrupted by a cutting edge 19. In the direction of rotation of the impeller 3, a cutting angle of the cutting edge 19 flattens outwards from the cutting ring base body 18 to a tip of the cutting tooth 16.

A cutting angle of the outer cutting teeth 16 or the outer cutting edges 19, facing the cutting head cutting edges 13, is 55°, whereby the cutting angle of the inner cutting teeth 16 is 52.5°. In the direction of rotation of the impeller 3, the cutting angle is flatter and is 20° on the outside and 10° on the inside. Each cutting tooth 16 protrudes at least 17 mm outward from the cutting ring base body 18, whereby the inner cutting teeth 16 extend further axially away from the cutting ring base body 16 than the outer cutting teeth 16. The cutting teeth 16 are also radially "sharpened", namely flattened on the outside by 37° and on the inside by 33° compared to the disk-like cutting ring base body 16 towards the opening 17. Other cutting angles and dimensions are also conceivable.

Fig. 4 shows a closed two-channel impeller 3 and the cutting head 1 of the pump in a perspective half-open view on the left and in a half-open plan view on the right according to the preferred embodiment of the invention. The cutting head 1 is further provided with the Fig. 4 not shown impeller 3 stationary in axial extension of the same for interaction with the also in Fig. 4 not shown cutting ring 2. The cutting head 1 is designed as previously described with a cutting head base body 8 with the plurality of cutting segments 11 with in particular axially extending cutting head cutting edges 13 for crushing the solid material, wherein cutting head cutting edges 13 extend radially away from the cutting head base body 8.

The disk-like impeller 3 has, in the usual way, two helical blades 23, each of which extends from an inlet edge 24 facing the cutting head 1 at a central impeller opening 25 to the outer radial edge of the impeller, as shown in Fig. 4 can be seen particularly on the right. The blades 23 are axially enclosed on the one hand by a radially extending support disk 26 on the motor side with 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 provided between the support disk 26 and cover disk 27 arranged parallel to one another. At the radially outer edge, the impeller 3 is open radially between the support disk 26, cover disk 27 and two adjacent blades 23 in a rectangular manner in a lateral plan view.

As is particularly evident from Fig. 4 As can be seen on the left, the cutting head cutting edges 13 are arranged at a distance from the inlet edges 24. Furthermore, the inlet edges 24 are provided spaced radially outwards from the inner edge of the impeller opening 25. In addition, the cutting head cutting edges 13 are arranged radially ahead in the direction of rotation of the impeller 3 and in particular radially overlapping the inlet edges 24, as indicated by the angle α in Fig. 4 indicated on the right. In other words, the entry edges 24 of the impeller 3 and cutting head cutting edges 13 do not lie 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 edges 13 and the entry edges 24 extend parallel to one another. Radially overlapping means in particular that the entry edges are at least partially arranged at the same axial height and/or at least partially in a common radial plane as the cutting head cutting edges. Preferably, the axial extent of the cutting head cutting edges is greater than the axial extent of the entry edges.

In the present case, as previously stated, two blades 23 are provided, while the cutting head 1 passing through the impeller opening 25 has four cutting head cutting edges 13. Of the four cutting head cutting edges 13, however, only the cutting head cutting edges 13 of the non-shortened cutting segments 11 with the blades 23. In the axial direction, the shortened cutting segments 11 are provided on the suction side in front of the blades 23, so that there is no transfer of the cutting head cutting edges 13 of the shortened cutting segments 11 with the blades 23. If, for example, eight cutting segments 11 are provided in an alternative embodiment, the impeller 3 expediently 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. A further seal is formed in that the cutting ring 2 at least partially encloses the impeller 3 to form a conical sealing gap.

The embodiments described are merely examples which can be modified and/or supplemented in many ways within the scope of the claims. list of reference symbols cutting head 1 cutting ring 2 wheel 3 pump housing 4 suction side 5 cutting head screw 6 cutting ring screw 7 cutting head body 8 drilling 9 peripheral surface 10 cutting segment 11 liquid inlet side 12 cutting head cutting edge 13 Page 14 federal government 15 cutting tooth 16 opening 17 cutting ring base body 18 cutting edge 19 material recess 20 valley 21 deepening 22 shovel 23 leading edge 24 impeller opening 25 support disc 26 cover plate 27

Claims (11)

1. Pump for a solids-loaded fluid, comprising an impeller (3) and a cutting ring (2), wherein the cutting ring (2) comprises a cutting ring base body (18) forming an opening (17) for cooperation with a cutting head (1) and is stationarily connected to the pump in axial extension of the impeller (3), wherein

   a plurality of cutting teeth (16) with respective at least outer cutting edges (19) oriented away from the impeller (3) in the direction of a suction side (5) of the pump are provided at the cutting ring base body (18) around the opening (17),

   the cutting teeth (16) extend axially outwardly from the cutting ring base body (18) at least in the direction of the suction side (5),

   in a valley (21) between two at least outwardly extending cutting teeth (16), a radially outwardly extending axial depression (22) is provided in the cutting ring base body (18),

   characeterized in that

   at least in each of the outwardly extending cutting teeth (16) a radially outwardly extending material recess (20) is formed.
2. Pump according to the previous claim, wherein the material recess (20) is provided in direction of rotation of the impeller (3) behind the cutting edge (19).
3. Pump according to any of the previous claims, comprising inwardly extending inner cutting teeth and (16) and outer cutting teeth (16), wherein the outer cutting edge (19) of a valley (21) between two outwardly extending cutting teeth (16) and the inner cutting edge (19) of a valley (21) between two inwardly extending cutting teeth (19) overlap axially.
4. Pump according to any of the previous claims, with inwardly extending inner cutting teeth (16) and outer cutting teeth (16), wherein the inner and outer cutting edges (19) extend axially wave-like or sinusoidally around the opening (17) and/or the cutting ring base body (18) is radially flattened in the valley (21) outwardly.
5. Pump according to any of the previous claims, with inwardly extending inner cutting teeth and (16) and outer cutting teeth (16), wherein in an axial extension between a tip of an outer cutting tooth (16) and a tip of an inner cutting tooth (16) around the opening (17) the inner cutting edge (19) and the outer cutting edge (19) are respectively formed.
6. Pump according to any of the previous claims, wherein in the direction of rotation of the impeller (3), an axial slope of the cutting edge (19) flattens outwardly from the cutting ring base body (18) to a tip of the cutting tooth (16).
7. Pump according to any of the previous claims, with inwardly extending inner cutting teeth and (16) and outer cutting teeth (16) and two, three, four, six or eight cutting teeth (16) oriented alternately outwardly and inwardly.
8. Pump according to any of the previous claims, wherein the cutting ring base body (18) is configured disc-like and the cutting teeth (16) extend axially away from the bottom face of the cutting ring base body (18).
9. Pump according to any of the previous claims, wherein an axial cutting angle of the cutting edges (19) in the direction of rotation of the impeller (3) is shallower than the cutting angle opposite to the direction of rotation.
10. Pump according to any of the previous claims, comprising inner cutting teeth (16) and outer cutting teeth (16), wherein the inner cutting teeth (16) extend axially away from the cutting ring base body (18) to a greater extent than the outer cutting teeth (16).
11. Pump comprising a cutting ring according to any of the previous claims and comprising the cutting head (1) connected torque-proof to the impeller (3), wherein the cutting head (1) comprises a plurality of cutting head cutting edges (13) which cooperate with the cutting edges (19) in chopping the grasped solid material.

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