Blood pump

Abstract

The present invention relates to a blood pump having a pump housing rotatably mounted by being coupled to a rotatably mounted rotation shaft, the pump housing together surrounding a main flow path, a bottleneck-shaped inlet region in which a blade assembly having n blades is disposed, the blades being oriented radially with respect to the rotation shaft, each having a flat shape and being disposed equidistant from one another around the rotation shaft, and a rotary motor disposed within the inner housing downstream and adjacent to the bottleneck-shaped inlet region, the rotary motor being operatively connected to the blade assembly via a magnetic coupling for rotating the blade assembly; The inner housing, together with the pump housing, encloses a flow path continuous with the main flow path, and together with the blade assembly, encloses a secondary channel that is fluidly connected to the main flow path, the secondary channel passing through the blade assembly and fluidly connected to at least one flushing channel that opens into the bottleneck-shaped inlet area, and the inner housing further comprises a lower bearing facing the blade assembly for rotatably receiving the lower end of the rotating shaft, the upper end of the rotating shaft being positioned in the bottleneck-shaped inlet area and attached to a bearing sleeve that is indirectly fixed to the pump housing, and a hollow cylindrical pump housing portion. The present invention is characterized in that three flushing channels, each having a flushing channel longitudinal axis oriented parallel to the axis of rotation, are evenly distributed around the axis of rotation, and each of the three flushing channels has a flushing channel cross-section oriented perpendicular to the axis of rotation, each of the cross-sections being kidney-shaped and surrounding the axis of rotation in a sector-like manner.

Description

[Technical field]

[0001] The present invention relates to a blood pump having a pump housing, which is rotatably mounted in association with a rotatably mounted rotating shaft, which together with the pump housing surrounds a main flow path and has a bottleneck-shaped inlet area in which a blade assembly having n blades is arranged, the blades being oriented radially with respect to the rotating shaft, each having a flat shape and being arranged equidistant from each other around the rotating shaft. Downstream of the bottleneck-shaped inlet area is a hollow cylindrical pump housing part, in which a rotary motor is arranged in the inner housing, which is operatively connected to the blade assembly via a magnetic coupling for rotating the blade assembly. The inner housing together with the pump housing surrounds a flow path continuous with the main flow path and together with the blade assembly surrounds a secondary channel in fluid communication with the main flow path, the secondary channel passing through the blade assembly and fluidly connected to at least one flushing channel opening into the bottleneck-shaped inlet area. The inner housing further comprises a lower bearing facing the blade assembly for rotatably receiving a lower end of the rotating shaft, the upper end of the rotating shaft being mounted in a bearing sleeve arranged in the bottleneck-shaped inlet area. [Background technology]

[0002] A blood pump is described in DE 19626224 A1, in whose pump housing a blade assembly is arranged, which is mounted rotatably around an axis of rotation passing through the center of the pump housing together with a rotating shaft, the rotating shaft being rotatably mounted at its ends in upper and lower bearings, the lower bearing being mounted above an inner housing, the inner housing being arranged downstream of the blade assembly in the pump housing and enclosing an electric rotary drive, which is operatively connected to the blade assembly via a magnetic coupling, the blade assembly being rotatably arranged coupled to the rotating shaft.

[0003] The helical impeller of the blade assembly together with the inner wall of the pump housing encloses a main axial flow passage, in which the blood flow through the blood pump is pressure-driven. In addition, the blade assembly has a secondary or flushing channel that hydraulically connects the suction side of the blade assembly with its rear side. In this way, blood can enter and flow through the rear gap between the blade assembly and the inner housing. A dead water area behind the blade assembly is thus effectively avoided.

[0004] US 2018 / 0050140 A1 discloses a blood pump having an impeller with helical blades and pierced by six so-called washout channels, the washout channels having at least one tangential component and a substantially circular channel cross-section.

[0005] EP 1727987 describes a blood pump having a blade assembly rotatably mounted in a pump housing via a magnetic bearing, the blades of which may be flat, spiral or otherwise curved. The magnetic bearing of the blade assembly makes it possible to realize a low-cost and low-wear pump, in particular providing a bearing of the blade assembly that is free of contact with the pump housing. The absence of bearing struts connected to the pump housing can at least reduce the problem of thrombus formation in the inflow region of the blood pump. Known blade assemblies are supported only by ball bearings that are mounted in an inner housing that surrounds the rotary motor.

[0006] A comparable blood pump with magnetic bearings for the blade assemblies can be found in EP 2566533 and has a metallic conical pin which is connected to an inner housing within the pump housing for dissipation of frictional heat generated by operation, and to which the blade assemblies are rotatably mounted via a ball profile.

[0007] All known blood pumps based on the principle of rotation of a blade assembly utilize the centrifugal effect of the rotating blade assembly to generate flows and pressures in the blood pump. This effect generates, in addition to a main flow along a main flow path radially bounded by the blade assembly and the inner and pump housings, a series of secondary flows branching off from the main flow and flowing from there through intermediate spaces in the further pump. To prevent the design-related intermediate gaps between the blade assembly and the inner housing surrounding the rotary motor from constituting dead spaces for the flow and the associated risk of thrombus formation, the blade assembly has so-called flushing channels, whereby a secondary blood flow passes through the intermediate gaps and the flushing channels fluidly connected thereto under the prevailing pressure conditions. Even without special precautions, a secondary flow is formed through the flushing channels passing through the blade assembly, counter to the main flow direction. Summary of the Invention

[0008] The present invention is based on the problem of providing a blood pump having a pump housing, which comprises a bottleneck-shaped inlet area, coupled to a rotatably mounted rotating shaft, which surrounds a main flow path together with said pump housing and a blade assembly having n blades arranged thereon, said blades being radially oriented with respect to said rotating shaft, each having a flat shape and being arranged equidistant from one another around said rotating shaft, such that the efficiency of the blood pump is increased, i.e. the blood volume transported by the blood pump is achieved with a lower energy input, and a rotary motor arranged in an inner housing downstream and adjacent to said bottleneck-shaped inlet area, said rotary motor being arranged in said blade assembly. a hollow cylindrical pump housing part, the inner housing further comprising a lower bearing facing the blade assembly for rotatably receiving a lower end of the rotating shaft, the upper end of the rotating shaft being mounted in a bearing sleeve arranged in the bottleneck-shaped inlet area. In particular, the aim is to significantly reduce the operating speed of the rotary driven blade assembly, without reducing the amount of blood transported, as compared to known blood pumps. By means of measures aimed at a more economical operation of the blood pump and the associated desired reduction in operating speed, the blood transport achieved with the aid of the blood pump is furthermore achieved more gently.

[0009] The solution to the problem underlying the present invention is set forth in claim 1. Features advantageously forming a blood pump according to the solution are the subject of the dependent claims and the detailed description, with particular reference to the exemplary embodiments shown in the drawings.

[0010] A blood pump according to the solution having the features specified in the preamble of claim 1 is characterized in that it has three separate flushing channels evenly distributed around the axis of rotation, each having a flushing channel longitudinal axis oriented parallel to the axis of rotation, and each of the three flushing channels has a flushing channel cross-section oriented perpendicular to the axis of rotation, each of said cross-sections being kidney-shaped and surrounding the axis of rotation in a sector-like manner.

[0011] Within the scope of numerous flow tests with blood pumps of different designs, it was possible to find the above blood pump design with optimized hydrodynamic properties. This is reflected in particular in the fact that the maximum discharge volume at any given rotation speed can be achieved by specially selecting the shape and number of flushing channels oriented parallel to the flushing channel longitudinal axis in conjunction with respective flat-shaped blades extending radially to the axis of rotation and equidistant from each other around the axis of rotation. In other words, compared to known blood pumps of the same size, the blood pump according to the solution can handle any discharge volume at a lower rotation speed, which results in less mechanical stress being experienced by the blood flowing through the blood pump.

[0012] Preferably, each of the kidney-shaped flushing channel cross-sections is surrounded by a periphery having a radially outer convex peripheral contour facing away from the axis of rotation and a radially inner concave peripheral contour facing towards the axis of rotation, whereby the concave peripheral contours of the three flushing channel cross-sections each lie on a first imaginary circular line centered on the axis of rotation, while the convex peripheral contours of the three flushing channel cross-sections each lie on a second imaginary circular line centered on the axis of rotation and whose radius is greater than the radius of the first circular line.

[0013] An arrangement of six blades, evenly distributed around the axis of rotation, has proven to be particularly advantageous.

[0014] In a particularly preferred embodiment, each of the six blades has a radial extension extending along the axis of rotation from the aforementioned second imaginary circular line, which in axial projection onto the blade assembly defines in each case a concave peripheral contour of the flushing channel cross-section, to a third imaginary circular line arranged about the axis of rotation, the radius of the second imaginary circular line being smaller than the radius of the third imaginary circular line, which radius preferably corresponds at most to the radius of the circular periphery of the blade assembly in axial projection onto the axis of rotation.

[0015] In an alternative embodiment of the blood pump, the six blades are divided into two groups, a first group and a second group, respectively, with respect to their shape and size, as well as their arrangement on the blade assembly. For example, of the six blades, three blades belonging to the first group, hereinafter referred to as primary blades, each have a radial extension extending along the axis of rotation, in axial projection onto the blade assembly, from a first imaginary circular line that defines the concave peripheral contour of the aforementioned kidney-shaped flushing cross section, up to a third imaginary circular line that is centered on the axis of rotation and corresponds, as in the above case, to the radius of the circular periphery of the blade assembly.

[0016] On the other hand, the three blades belonging to the second group, the so-called secondary blades, each have a radial extension extending along the axis of rotation from the second imaginary circular line in the axial projection onto the blade assembly to a third imaginary circular line centered about the axis of rotation. In this case, the primary and secondary blades are each arranged alternately around the axis of rotation. Further structural features and design details in this regard can be found in the detailed description with reference to the drawings.

[0017] Furthermore, the upper and lower bearings, to which the upper and lower ends of the shaft are rotatably but axially fixedly joined, respectively, are preferably made of a ceramic or wear-resistant plastic material, preferably UHM plastic. The lower bearing, mounted on the inner housing, preferably comprises a pot-shaped inlay element, which is fixedly joined to the inner housing, rotatably and axially fixedly opening at the lower end of the shaft, and which is made of a material different from the material of which the inner housing itself is made. [Brief description of the drawings]

[0018] Without limiting the general inventive concept, the invention will now be described by way of example only on the basis of examples of preferred embodiments with reference to the drawings. [Figure 1a] FIG. 2 shows a plan view of the pump housing. [Figure 1b] FIG. 2 shows a side view of the pump housing. [Diagram 2] 1 shows a longitudinal section through the pump housing in the region of the inlet. [Diagram 3] The upper bearing element is shown. [Figure 4] FIG. 2 shows a longitudinal cross-sectional view of a pump housing. [Diagram 5] FIG. 1 is a plan view of a blade assembly according to a first embodiment. [Figure 6] FIG. 13 shows a perspective view of a blade assembly according to a second embodiment. [Figure 7] FIG. 11 is a plan view of a blade assembly according to a second embodiment. [Figure 8a] FIG. 2 shows a side view of a blade assembly with a cover plate. [Figure 8b] FIG. 2 shows a side view of a blade assembly with a cover plate. [Figure 8c] FIG. 2 shows a side view of a blade assembly with a cover plate. [Figure 8d] FIG. 2 shows a side view of a blade assembly with a cover plate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Figures 1a and 1b show a side view and a plan view of a pump housing 1 of a blood pump. The pump housing 1, which is substantially bottleneck-shaped at the top, has an inlet 1' through which blood passes and enters the blood pump in the longitudinal extension of the pump housing 1. The pump housing 1 can be divided into a bottleneck-shaped inlet area 2 and a hollow cylindrical pump housing part 7 flush adjacent to the inlet area. An outlet 1'', which is oriented substantially perpendicular to the inlet, is provided in the area of ​​the hollow cylindrical pump housing part 7.

[0020] In order to keep the wall thickness of the pump housing 1 of the blood pump as thin as possible, inter alia for cost and weight reasons, four stabilizing struts 1''' are attached to the outside of the pump housing 1 in the area of ​​the bottleneck-shaped inlet area 2.

[0021] Immediately downstream of the inlet 1', four support struts 1st are connected on one side to the inner wall of the pump housing 1 and converge at right angles to form a kind of inlet star, together forming the spatial attachment for the upper rotary bearing described below. The support struts 1st are optimized in terms of fluid dynamics in order to create the lowest possible flow resistance for the blood flow entering through the inlet 1'.

[0022] The illustrated blood pump represents a mixed flow pump, i.e. the blood flow entering through an inlet 1' in the longitudinal extension of the pump housing 1 is split perpendicular to the inflow direction into blood flow exiting the pump housing 1 tangentially through an outlet 1''.

[0023] FIG. 2 shows a partial longitudinal section through the upper part of the pump housing 1 in the region of the bottleneck-shaped inlet area 2. Downstream of the inlet 1' are arranged the support struts 1st which are connected integrally to the pump housing 1 and which, optimised in terms of hydrodynamics, come together to form a kind of inlet star and which lead into the centre of a bearing structure 1L of hydrodynamically favourable capsule-like design. The pump housing 1 together with the support struts 1st and the bearing structure 1L is preferably integrally formed from plastic, preferably in an injection moulding process. A bearing sleeve 15, preferably made of ceramic or an almost wear-free plastic material, is inserted flush, i.e. without edges, into the bearing structure 1L, with the upper end of the rotating shaft 3 axially fixed and rotatably joined in the bearing sleeve (see also FIG. 3).

[0024] FIG. 4 shows a further partial longitudinal section through the pump housing 1 , showing the bottleneck-shaped inlet area 2 and part of the adjacent hollow cylindrical pump housing section 7 .

[0025] The pump housing 1 comprises a rotating shaft 3, an upper end 3o of the rotating shaft which is axially fixed and rotatably connected to a bearing sleeve 15, a blade assembly 4 which is coupled and rotatably connected to the rotating shaft 3, and an inner housing 8, and above the inner housing 8 there is a lower bearing 14 having an inlay element 21 to which the lower end 3u of the rotating shaft is axially fixed and rotatably attached.

[0026] The blade assembly 4, which is bonded and rotatably connected to the rotating shaft 3, has six flat blades 5, which in the exemplary embodiment shown in Figure 4 are of the same shape and size. The six blades 5 are arranged equidistant from each other around the rotating shaft 3. These radially outer blade contours, together with the inner wall of the pump housing 1, enclose a main flow passage 6 through which blood flows in a mainstream direction HR during operation of the blood pump.

[0027] In addition, please refer at this point to Figure 5, which shows the blade assembly 4 in an axial plan view in the flow direction. The blade assembly 4 is bordered by three flushing channels 13 evenly distributed around the axis of rotation 3. Each of the flushing channels 13 has a kidney-shaped flushing channel cross-section 17, each of which has a convex peripheral contour 17' facing away from the axis of rotation 3 and a radially inward concave peripheral contour 17'' facing towards the axis of rotation 3.

[0028] The concave peripheral contours 17'' of the three flushing channel cross-sections 17 lie on a first imaginary circular line 18 arranged about the axis of rotation 3, while the convex peripheral contours 17' of the three flushing channel cross-sections 17 lie on a second imaginary circular line 19 arranged about the axis of rotation.

[0029] In the illustrated exemplary embodiment, all blades 5 have a respective radial extension in which all blade ends 5' pointing radially towards the axis of rotation 3 lie on a second imaginary circular line 19 in axial projection onto the blade assembly 4, while the radially outer ends 5'' of the blades 5 lie on a third imaginary circular line 20, which corresponds to the circumferential edge of the blade assembly 4 or is spaced therefrom by a small distance Δx, with 0.1 mm<=δx<=2 mm.

[0030] The three flushing channels 13 run parallel to the axis of rotation 3 and each have a lower flushing channel opening 13u and an upper flushing channel opening 13o which are optimized in terms of hydrodynamics.

[0031] The upper flushing channel openings 13o open into two flow regions S1, S2, each bounded by two blades 5. The upper flushing channel openings 13o are each shaped like an orchid flower and provide the lowest possible flow resistance for the flushing channel flow SR directed countercurrently to the main flow HR flowing along the main flow path 6. This allows the countercurrent flushing flow SR to pass almost turbulently, but at least with weak turbulence, into the main flow HR of the bottleneck-shaped inlet region 2.

[0032] The lower flushing channel opening 13u of each flushing channel 13 is also designed to be flow optimized for the lowest possible flow resistance. To this end, the lower bearing 14 mounted on the inner housing 8 is hydrodynamically oriented in the direction of the lower flushing channel opening 13u to provide a flow gate for the countercurrent flushing channel flow SR that provides the lowest possible inlet resistance of the various flushing channels 13.

[0033] The blade assembly 4 further includes a magnetic coupling 10 that is magnetically coupled to a rotary motor 9 mounted within the inner housing 8. The permanent magnet or magnet arrangement required for the magnetic coupling 10 is fully integrated within the blade assembly 4, preferably made from a wear-free plastic material. The magnet arrangement can be fully encapsulated as part of the casting process or additive manufacturing process that creates the blade assembly 4.

[0034] Figures 6 and 7 show an alternative embodiment of the blade assembly 4 in a perspective view and an axial plan view. In contrast to the blade assembly shown in Figures 4 and 5, the blade assembly 4 in Figures 6 and 7 has three primary blades 5P of identical shape and size, which alternate in an axial arrangement around the rotation axis 3 with secondary blades 5S of a radially shorter design. The blades 5P and 5S are all of flat shape. The primary blades 5P have a radial extension whose edge extends from the first imaginary circular line 18 to the third circular line 20. On the other hand, the secondary blades 5S only extend from the second imaginary circular line 19 to the third circular line 20.

[0035] FIG. 6 shows that the upper flushing channel opening 13o opens like an orchid between two primary blades 5P, and in each case the secondary blade 5S divides the upper opening area into two flow areas S1 and S2.

[0036] Each of the three primary blades 5P terminates, directly or indirectly, at the axis of rotation 3 with its end pointing radially towards the axis of rotation 3. The secondary blades 5S have planar extensions which, apart from a short radial extension, are otherwise of the same shape and dimensions as the primary blades 5P.

[0037] 8a, 8b, 8c and 8d respectively show an alternative embodiment of the blade assembly 4 with a cover disk 22 in various views or representations. FIG. 8a shows the blade assembly 4 in a perspective view from above, FIG. 8b in a longitudinal section, FIG. 8c from the side and FIG. 8d from above. The blade assembly 4 is similar to the blade assemblies already shown in FIGS. 4 and 5, i.e. the individual blades 5 are all of identical design and their radially inner blade edges 5' adjoin the convex peripheral contour 17' of the kidney-shaped flushing channel cross-section 17. In addition, the lateral edges 5K of the blades 5 facing the flow (see FIG. 4) are connected to a cover disk 22 which defines a main flow path 6 together with the inner wall of the pump housing 1. The cover disk 22 is conical and has otherwise straight frustoconical surfaces and, together with the inner wall of the pump housing 1, always defines a given main flow path 6 regardless of the rotation speed of the blade assembly 4. The cover disk 22 helps reduce the shear and mechanical stresses that affect blood flow as it passes through the blood pump, allowing the blood to pass more gently through the blood pump.

[0038] Of course, the blade assembly 4 according to the exemplary embodiment shown in Figures 6 and 7 can also be provided with a cover disk 22 accordingly. [Explanation of symbols]

[0039] 1: Pump housing 1': Inlet 1'': Outlet 1'): Stabilizing strut 1st: Support strut 1L: Bearing structure 2: Bottleneck inlet region 3: Rotation axis 3o: Top of the rotation axis 3u: Lower end of the rotating shaft 4: Blade Assembly 5: Blade 5P: Primary blade 5S: Secondary blade 5': Radially inner blade edge 5): Radially outer blade edge 5K: Side edge 6: Main channel 7: Hollow cylindrical pump housing section 8: Inner housing 9: Rotary motor 10: Magnetic coupling 11: Continuous flow channel 12: Secondary channel 13:Flushing channel 13u: Lower flushing channel opening 13o: Upper flushing channel opening 14: Lower bearing 15: Bearing sleeve 16: Flushing channel longitudinal axis 17: Flushing channel cross section 17': Convex peripheral contour 17): Concave peripheral contour 18: First circular line 19: Second circular line 20: Third circular line 21: Inlay element 22: Cover disc SR: Secondary flow, flashing flow HR: Mainstream S1, S2: flow domain R1, R2, R3: Radius

Claims

1. A blood pump having a pump housing (1), a bottleneck-shaped inlet area (2) rotatably mounted in association with a rotatably mounted rotating shaft (3), surrounding a main flow path (6) together with the pump housing (1), through which blood flow passes in a main flow direction (HR) during operation of the blood pump, and in which a blade assembly (4) having n blades (5) is arranged, the blades (5) being radially oriented with respect to the rotating shaft, each having a flat shape and being equidistant from one another around the rotating shaft (3); A hollow cylindrical pump housing portion (7) is provided with an outlet (1'') adjacent downstream of the bottleneck-shaped inlet region (2) and oriented substantially perpendicular to the inlet, an inner housing (8) is provided with a rotary motor (9) arranged therein, the rotary motor (9) being operatively connected to the blade assembly (4) via a magnetic coupling (10) for rotating the blade assembly (4), the inner housing (8) together with the pump housing (1) enclosing a flow path (11) in continuity with the main flow path (6), and a secondary channel in fluid communication with the main flow path (6) together with the blade assembly (4). a hollow cylindrical pump housing part (7) surrounding a secondary channel (12) passing through the blade assembly (4) and fluidly connected with at least one flushing channel (13) opening into the bottleneck-shaped inlet area (2), the inner housing (8) further comprising a lower bearing (14) facing the blade assembly (4) for rotatably receiving a lower end (3u) of the rotating shaft (3), the upper end (3o) of the rotating shaft being located in the bottleneck-shaped inlet area and mounted on a bearing sleeve (15) indirectly fixed to the pump housing (1), three flushing channels (13), each having a flushing channel longitudinal axis (16) oriented parallel to said axis of rotation (3), being evenly distributed around said axis of rotation (3), and during operation of said blood pump, a flushing channel flow (SR) is formed through each of said three flushing channels (13), said flushing channel flow (SR) being oriented counter to said main flow direction (HR) along said main flow path (6); Each of the three flushing channels (13) has a flushing channel cross-section (17) oriented perpendicular to the axis of rotation (3), each cross-section (17) being kidney-shaped and surrounding the axis of rotation (3) in a sector-like manner.

2. said kidney-shaped flushing channel cross-sections (17) are each surrounded by a periphery having a radially outer convex periphery contour facing away from said axis of rotation and a radially inner concave periphery contour facing towards said axis of rotation, the concave peripheral contours of the three flushing channel cross-sections (17) lie on a first imaginary circular line (18) arranged about the axis of rotation (3); 2. The blood pump according to claim 1, wherein the convex peripheral contours of the three flushing channel cross-sections (17) lie on a second imaginary circular line (19) arranged about the axis of rotation (3).

3. 3. The blood pump according to claim 1, wherein the number of blades n is six.

4. each of the blades (5) has a radial extension extending along the axis of rotation (3) from the second imaginary circular line (19) to a third imaginary circular line (20) arranged about the axis of rotation (3) in an axial projection onto the blade assembly (4); 3. The blood pump of claim 2, wherein the radius (R2) of the second imaginary circular line (19) is smaller than the radius (R3) of the third imaginary circular line (20).

5. each of the n / 2 blades (5) of the first group (G1) has, in axial projection onto the blade assembly (4), a radial extension extending along the axis of rotation (3) from the second imaginary circular line (19) to a third imaginary circular line (20) arranged about the axis of rotation (3), the radius (R3) of the third circular line (20) being greater than the radius (R2) of the second circular line (19); each of the n / 2 blades (5) of the second group (G2) has a radial extension extending along the axis of rotation (3) from the first imaginary circular line (18) to the third imaginary circular line (20) arranged about the axis of rotation (3) in an axial projection onto the blade assembly (4); 3. The blood pump according to claim 2, wherein the blades of the first and second groups (G1, G2), respectively, are arranged alternately around the axis of rotation (3).

6. 6. The blood pump according to claim 1, wherein the lower bearing (14) attached to the inner housing (8) comprises a pot-shaped inlay element (21) fixedly joined to the inner housing (8), the lower end (3u) of the rotating shaft (3) being rotatably and axially fixedly open, and made of a material different from the material of the inner housing (8).

7. 7. The blood pump according to claim 6, wherein the material of the inlay element (21) consists of ceramic or UHM plastic.

8. 8. The blood pump according to claim 7, wherein the bearing sleeve (15) is made of the same material as the inlay element (21).

9. 9. The blood pump according to any one of the preceding claims, wherein the blade assembly (4) comprises a cover disc (22) which together with the pump housing (1) defines the main flow path (6).

10. 10. The blood pump of claim 9, wherein the cover disc (22) has a straight frustoconical surface oriented towards the pump housing.

Images