FLUID PUMP

Abstract

A fluid pump conveys a fluid, such as blood. A fluid channel that is bounded by a channel wall and a rotor arranged in the fluid channel and that is rotatably mounted about a pivot point of the bearing with a mechanical, hydrodynamic and/or hydrostatic, axial and radial bearing. The fluid channel has a spherical section and the rotor has a rotor body and a conveying element that is arranged within the spherical section of the fluid channel and configured to generate a substantially spherical rotational area of the rotor. The spherical center of the spherical section of the fluid channel and the spherical center of the spherical rotational area substantially coincide with the pivot point so that a minimum distance between the rotor and the channel wall is maintained in the spherical section upon a tilting of the rotor.

Claims

1. A fluid pump for conveying a fluid comprising: a fluid channel that is bounded by a channel wall, the fluid channel comprising a spherical section; a rotor disposed in the fluid channel, the rotor is rotatably mounted about a pivot point of a bearing by a mechanical, hydrodynamic and/or hydrostatic, axial and radial bearing, wherein the rotor comprises: a rotor body; and a conveying element disposed within the spherical section of the fluid channel and that is configured to generate a substantially spherical rotational area of the rotor; and wherein a spherical center of the spherical section of the fluid channel and a spherical center of the substantially spherical rotational area coincide with the pivot point such that a minimum distance between the rotor and the channel wall is maintained in the spherical section during a tilting of the rotor.

2. The fluid pump of claim 1, wherein the bearing comprises a ball cup bearing or a pin bearing.

3. The fluid pump of claim 1, wherein the bearing comprises a passively magnetic bearing, with the passively magnetic bearing being formed as a rocker bearing for returning a tilt of the rotor or configured to axially preload the rotor with respect to the fluid channel.

4. The fluid pump of claim 1, further comprising: a motor stator disposed at the channel wall of the flow channel; and a motor magnet integrated in the rotor body or in the conveying element, wherein a passively magnetic rocker bearing is implemented by a magnetic attraction or repulsion between the motor stator and the motor magnet.

5. The fluid pump of claim 1, wherein the fluid channel is shaped as conical, tapering toward the bearing on a side disposed opposite the bearing, further wherein a taper angle of the fluid channel corresponds to a maximum tilt angle of the rotor within the fluid channel.

6. The fluid pump of claim 5, wherein the rotor body is shaped as conical, tapering in a direction away from the bearing on a side disposed opposite the bearing, further wherein a taper angle of the rotor body corresponds to a maximum tilt angle of the rotor within the fluid channel.

7. The fluid channel of claim 1, wherein the bearing comprises a hydrostatic or hydrodynamic auxiliary bearing disposed in the fluid channel to bound the tilt of the rotor.

8. The fluid pump of claim 7, wherein the hydrostatic or hydrodynamic auxiliary bearing is formed by guide blades arranged at the channel wall.

9. The fluid pump of claim 1, wherein hydrodynamically active elements are disposed on a side of the fluid channel opposite the bearing at the channel wall or at the rotor to improve a nestling of the rotor to the channel wall upon the tilting of the rotor.

10. The fluid pump of claim 1, wherein the fluid channel further comprises: a fluid inlet; and a fluid outlet, wherein the bearing is disposed at the fluid inlet, at the fluid outlet, or at a center of the fluid channel.

11. The fluid pump of claim 10, wherein the fluid outlet comprises an axial, tangential, or axially tangentially mixed fluid outlet.

12. The fluid pump of claim 10, wherein the fluid pump has a volute in the region of the fluid outlet, wherein the volute comprises a ring volute, a logarithmic volute, or a volute having an axial portion.

13. The fluid pump of claim 1, wherein the bearing comprises a mechanical bearing, wherein the mechanical bearing comprises a hemocompatible, hard, wear resistant, or thermally conductive material, further wherein the material comprises a ceramic material, such as aluminum oxide (Al2O3), silicon carbide (SiC), zirconium oxide (ZrO2), or silicon nitride (Si3N4), a mixed ceramic material, such as Al2O3/SiC, aluminum reinforced zirconium oxide (ATZ), or zirconium oxide reinforced aluminum oxide (ZTA), crystalline, such as diamond, sapphire, ruby, or quartz, or tantalum nitride, such as a tantalum nitride thin film, and comprises a sliding layer, such as diamond-like carbon (DLC), SiN, or tungsten carbide/carbon (WC/C).

14. The fluid pump of claim 1, wherein the bearing is axially mechanically displaceable to set an ideal distance between the fluid channel and the conveying element.

15. The fluid pump of claim 14, wherein the bearing is axially mechanically displaceable with a thread before the putting into operation of the fluid pump.

16. The fluid pump of claim 1, wherein the bearing comprises a magnetic bearing and the motor stator is axially displaceable so that a preload of the rotor in the bearing can be set.

17. The fluid pump of claim 1, wherein the fluid channel comprises: a volute, in proximity to a fluid outlet, configured to expand in axial direction and in radial direction.

18. The fluid pump of claim 1, wherein the fluid channel comprises: a volute, in proximity to a fluid outlet, having an axial and a radial portion, wherein the axial portion and the radial portion of the volute in an inlet section of the volute allow a 3-dimensional volute flow vector (v) at a radial angle that does not deviate more than 30° from a 3-dimensional fluid flow vector (f) of the fluid entering the volute at that radial angle when the rotor is operated at a design point, further wherein the 3-dimensional volute flow vector (v) is given by the surface normal of the fluid channel within the inlet section of the volute at the radial angle.

19. A fluid pump of claim 1, wherein the fluid channel comprises a diffuser with an opening angle between 5° and 20°, at a fluid outlet of the fluid channel.

20. A fluid pump of claim 1, wherein the fluid channel comprises a fluid outlet that is pivotable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The embodiments of a fluid pump will be described in more detail with reference to Figures, which illustrate examples of those embodiments. The same or different reference numerals may be used for the same or similar elements in the Figures and their explanation may be omitted in part. Non-limiting and non-exhaustive embodiments are described with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. The drawings, like referenced numerals, designate corresponding parts throughout the different views.

[0037] FIG. 1 is a blood pump mounted at the inlet side in accordance with a first embodiment,

[0038] FIG. 2 is a blood pump mounted at the inlet side in accordance with a second embodiment;

[0039] FIG. 3 is a blood pump mounted at the inlet side in accordance with a third embodiment;

[0040] FIG. 4 is a blood pump mounted at the inlet side in accordance with a fourth embodiment;

[0041] FIG. 5 is a blood pump mounted at the outlet side in accordance with a fifth embodiment,

[0042] FIG. 6 is the blood pump mounted at the outlet side in accordance with FIG. 5 with a rotor tilt;

[0043] FIG. 7 is a blood pump mounted at the outlet side in accordance with a sixth embodiment,

[0044] FIG. 8 is a blood pump mounted at the outlet side in accordance with a seventh embodiment,

[0045] FIG. 9 is a blood pump mounted at the outlet side in accordance with an eighth embodiment,

[0046] FIG. 10a is a cross sectional view of the blood pump in accordance with the eighth embodiment,

[0047] FIG. 10b is a side view of the blood pump in accordance with the eighth embodiment,

[0048] FIG. 11 is a blood pump mounted at the outlet side in accordance with a ninth embodiment, and

[0049] FIG. 12 is a blood pump mounted at the outlet side in accordance with a tenth embodiment.

DE′T′AILED DESCRIPTION

[0050] FIG. 1 shows a blood pump 1 in accordance with a first embodiment in a longitudinal sectional view. The blood pump 1 has a substantially hollow cylindrical pump housing 1a that is substantially rotationally symmetrical about an axis of rotation 7. The pump housing 1a has a spherical widening 1b in a middle region of the pump housing 1a. The blood pump 1 has a fluid channel 2 that is bounded by a channel wall 2b of the fluid pump 1 in an inner region of the pump housing 1a. The fluid channel 2 extends in an axial direction from an inlet region 3 to an outlet region 4. The spherical widening 1b is located between the inlet region 3 and the outlet region 4.

[0051] The fluid channel 2 has a spherical section 2a in the region of the spherical widening 1b. The blood pump 1 furthermore has a rotor 5 and a stator 6 in this region. The stator 6 comprises a drop-like element 6c that is arranged in a streamlined manner along the axis of rotation 7 in the fluid channel 2. The pump housing 1a is furthermore part of the stator 6. The drop-like element 6c is fixedly connected to the pump housing 1a via guide blades 9 that are likewise parts of the stator 6. In the pump housing 1a, a plurality of stator irons 6a are arranged in ring shape around the fluid channel 2 in the region of the widening 1b. The stator irons 6a are each surrounded by stator windings 6b in parallel with the channel wall 2b.

[0052] The front end of the drop-like element 6c at the inlet side forms an axially flushable mechanical ball cup bearing 8 for the rotor 5. The rotor 5 is rotatably mounted about the axis of rotation 7 radially and axially mechanically on the drop-like element 6c of the stator 6. The rotor 5 is held on the drop-like element 6c by a small rotor body 5a. The rotor body 5a rigidly connects conveying elements 5b to one another that make up a main portion of the rotor 5.

[0053] Permanent magnets 5c are integrated in the conveying elements 5b in an outer region of the conveying elements 5b disposed toward the channel wall 2b. The stator irons 6a and associated stator windings 6b form a plurality of electromagnetics that cooperate with the permanent magnets 5c to drive the rotor 5. The electromagnets 6a, 6b of the stator 6 together with the permanent magnets 5c of the rotor 5 serve a passive return of the rotor 5 on a tilting of the rotor 5 in the direction of the channel wall 2b and thus serve a fixing of the remaining two tilt degrees of freedom of the rotor 5.

[0054] A shape of the conveying elements 5b is furthermore adapted to a spherical curvature of the channel wall 2b on outer sides disposed toward the channel wall 2b so that the conveying elements 5b sweep over a spherical rotational area on a rotation of the rotor 5. The location of the rotor 5 in the fluid channel 2 and the position of the spherical portion 2a are furthermore aligned with one another such that the center of the spherical rotational area of the conveying elements 5b or of the rotor 5 and the center of the spherical section 2a of the fluid channel 2 substantially coincide with the swivel point of the bearing 8. A minimal or minimum distance between the conveying elements 5b or the rotor 5 and the channel wall 2b thereby also remains substantially constant on a tilting of the rotor 5 toward the channel wall 2b. A contact of the rotor 5 with the channel wall 2b and possible damage to the rotor 5 and impairment of the function of the blood pump 1 associated therewith are thereby prevented.

[0055] The conveying elements 5b serve the conveying of the blood to be conveyed by the blood pump 1 from the inlet region 3 to the outlet region 4 and are designed such that a conveying is made possible in a mixed radial and axial direction. The guide blades 9, in addition to the conveying elements 5b, provide an efficient conveying of the blood to the outlet 4 of the blood pump 1.

[0056] FIG. 2 shows a blood pump 1 in accordance with a second embodiment in a longitudinal sectional view. The blood pump 1 has a pump housing 1a having an inlet region 3 for the blood and an outlet region 4 for the blood. The pump housing 1a is substantially rotationally symmetrical with an axis of rotation 7. A fluid channel 2 that is bounded by a channel wall 2b leads through the pump housing 1a in an axial direction. The fluid channel 2 has a substantially drop-like shape between the inlet region 3 and the outlet region 4. The fluid channel 2 initially has a spherical section 2a downstream of the inlet region 3 before the fluid channel 2 tapers in the direction of the outlet region 4. A rotor 5 having a rotor body 5a is arranged in the drop-like region of the fluid channel 2. In the front region of the rotor 5 facing the inlet region 3, the rotor body 5a is designed in ring shape and is connected via conveying elements 5b to a drop-like element 5d that is part of the rotor body 5a. The drop-like element 5d tapers acutely toward the outlet region 4. A plurality of permanent magnets 5c are arranged in the ring-shaped region. The rotor 5 is radially and axially hydrodynamically or hydrostatically mounted in the spherical section 2a, with the channel wall 2b representing the hydrodynamic or hydrostatic bearing 8 in the spherical section. The drop-like element 5d of the rotor 5 is furthermore radially mounted by means of a ring-shaped hydrodynamic or hydrostatic bearing 13, with the hydrodynamic or hydrostatic bearing 13 being rigidly connected to the pump housing 1a via guide blades 9. The bearing 8 fixes the ring-shaped region of the rotor 5 in the axial and radial directions. The bearing 13 fixes the drop-like element 5d of the rotor 5 in the radial direction.

[0057] The blood pump 1 is equipped with a bearing-less motor stator to drive the rotor 5. A plurality of stator irons 6a are arranged around the drop-like region of the fluid channel 2 in the pump housing 1a. The stator irons 6a are wound around by stator windings 6b in the region of the tapering fluid channel 2 perpendicular to the channel wall 2b. The stator irons 6a contact the outer side of the spherical fluid channel in the region of the spherical section 2a. The stator irons 6a with stator windings 6b form electromagnets that cooperate with the permanent magnets 5c to drive the rotor 5.

[0058] In the spherical section 2a of the fluid channel 2, the ring-shaped region of the rotor 5 is likewise spherically shaped on the outer side disposed toward the channel wall 2b and is adapted to a curvature of the channel wall 2b. The center of the spherical curvature of the outer side of the ring-shaped region of the rotor 5 and the center of the spherical curvature of the spherical section 2a substantially coincide with the pivot point of the bearing 8 so that the minimal/minimum distance between the ring-shaped region of the rotor 5 and the channel wall 2b is also substantially constant on a tilting of the rotor 5. A contact of the rotor 5 with the channel wall 2b and possible damage to the rotor 5 and impairment of the function of the blood pump 1 associated therewith are thereby prevented.

[0059] The conveying elements 5b serve the conveying of the blood to be conveyed by the blood pump 1 from the inlet region 3 to the outlet region 4 and are designed such that a conveying is made possible in a mixed radial and axial direction. The guide blades 9 arranged downstream, in addition to the conveying elements 5b, provide an efficient conveying of the blood to the outlet of the blood pump 1.

[0060] The cooperation of the rotor magnets 5c and the motor stator 6a, 6b passively bounds a radial tilt of the rotor 5. A preload of the rotor 5 can additionally be set toward the outlet region 4 by the rotor magnets 5c and the motor stator 6a, 6b.

[0061] FIG. 3 shows a blood pump 1 in accordance with a third embodiment in a longitudinal sectional view. The blood pump 1 is similar to the blood pump of FIG. 2 except for the design of the motor stator 6b and an additional passive magnetic stator rocker bearing 11. The motor stator 6b is free of irons. The additional magnetic stator rocker bearing 11 is located in the rear region of the blood pump 1 facing the outlet region 4 and cooperates with the rotor magnets 10 that are arranged in the drop-like element 5d of the rotor 5. The stator rocker bearing 11 is radially repelling and thus holds the drop-like element 5d centrally in the fluid channel 2, with remaining tilt degrees of freedom being stabilized.

[0062] The further illustrated features of the blood pump 1 agree with the blood pump of FIG. 2. In the spherical section 2a of the fluid channel 2, the ring-shaped region of the rotor 5 is likewise spherically shaped on the outer side disposed toward the channel wall 2b and sweeps over a spherical rotational area on a rotation of the rotor 5. A curvature of the outer side of the ring-shaped region of the rotor 5 is adapted to a curvature of the channel wall 2b. The center of the spherical curvature of the outer side of the ring-shaped region of the rotor 5 and the center of the spherical curvature of the spherical section 2a substantially coincide with the pivot point of the bearing 8 so that the minimal/minimum distance between the ring-shaped region of the rotor 5 and the channel wall 2b is also substantially constant on a tilting of the rotor 5. A contact of the rotor 5 with the channel wall 2b and possible damage to the rotor 5 and impairment of the function of the blood pump 1 associated therewith are thereby prevented.

[0063] FIG. 4 shows a blood pump 1 in accordance with a fourth embodiment in a longitudinal sectional view. The blood pump 1 is similar in principle to the blood pump of FIG. 1. The hollow cylindrical pump housing 1a has an inlet region 3 and an outlet region 4 for the blood. A fluid channel 2 that is bounded by a channel wall 2b leads between the inlet region 3 and the outlet region 4. The fluid channel 2 has a spherical section 2a downstream of the inlet region 2 and tapers in drop form toward the outlet region 4.

[0064] The blood pump 1 substantially differs from the blood pump of FIG. 1 in the form of the rotor 5. The rotor body 5a of the rotor 5 has a conical shape that has a cutout 5e at the side facing the drop-like element 6c of the stator 6. The drop-like element 6c of the stator 6 engages into this cutout 5e and thus forms the axial and radial mechanical ball cup bearing 8 for the rotor 5. The rotor body 5a is positioned in the flow channel 2 such that a tip 5f of the conical shape of the rotor body 5a projects into the inlet region 3 downstream of the spherical section. A large part of a jacket surface of the conical shape lies in the spherical section 2a of the fluid channel 2 and extends quasi in parallel with the channel wall 2b.

[0065] Conveying elements 5b that convey the blood from the inlet region 3 in the direction of the outlet region 4 in a mixed radial and axial direction are arranged in the spherical region on the jacket surface of the rotor body 5a. The conveying elements 5b are arranged on the jacket surface and are shaped such that they sweep over a spherical rotational area on a rotation of the rotor 5. The conveying elements 5b are furthermore shaped and are positioned in the fluid channel 2 such that the center of the spherical rotational area and the center of the spherical section 2a of the fluid channel 2 substantially coincide with the pivot point of the bearing 8. This embodiment of the rotor 5 and the fluid channel 2 makes it possible that a minimal/minimum distance between the rotor 5 and the channel wall 2b also remains constant on a tilting of the rotor 5 and prevents the rotor 5 from contacting the channel wall 2b and the arising of damage to the rotor 5 or to the channel wall 2b or the impairment of the function of the blood pump 1 on the tilting of the rotor 5.

[0066] The blood pump 1 in a similar manner to the blood pump of FIG. 1 has guide blades 9 that are arranged downstream of the rotor 5 and that rigidly connect the drop-like element 6c to the pump housing 1a. The guide blades 9 support and improve a flow of the blood to the outlet region 4. Flushing bores for flushing the mechanical bearing that may be necessary are not shown, but can easily be introduced into the rotor.

[0067] FIGS. 5 and 6 show a blood pump 1 in accordance with a fifth embodiment in a longitudinal sectional view. The blood pump 1 has a substantially hollow cylindrical pump housing 1a having an inlet region 3 and an outlet region (not shown here) through which a fluid channel 2 leads from the inlet region 3 to the outlet region. The fluid channel 2 is bounded by a channel wall 2b and has a spherical section 2a toward the outlet region. The pump housing 1a has a flange-like broadened portion 1c in which the fluid channel 2 opens into a ring volute 12 downstream of the spherical region 2a. The outlet region (not shown here) is located in the ring volute 12.

[0068] A rotor 5 having a substantially cylindrical rotor body 5a is rotatably supported about an axis of rotation 7 in the fluid channel 2. For the mounting of the rotor 5, the blood pump 1 has a radial and axial mechanical ball cup bearing 8 that is arranged at the center of the spherical curvature of the spherical region 2a. Rotor magnets 5c are arranged in the middle region of the rotor body 5a and cooperate with a motor stator 6b arranged in the pump housing 1a and running around the rotor magnets 5c to drive the rotor 5. A magnetic rocker bearing 11 that cooperates with a bearing magnet 10 arranged adjacent to the rocker bearing 11 in the rotor body 5a is disposed toward the inlet region 3 in the pump housing 1a to stabilize tilt degrees of freedom of the rotor 5 in the front region of the blood pump 1 at the inlet side.

[0069] In the spherical region 2a, the rotor 5 has conveying elements 5b outwardly at the rotor body 5a in the spherical section that enable a conveying of the blood to be conveyed in a mixed radial and axial direction from the inlet region 3 into the ring volute 12. The ring volute 12 then changes a flow direction of the blood from the mixed radial and axial direction in a purely radial direction before the blood enters into the outlet region arranged in the ring volute 12. The conveying elements 5b further has a spherical outer contour corresponding to the spherical curvature of the spherical region 2a so that a rotational area results that is swept over by the conveying elements 5b on a rotation of the rotor 5. The curvature of this rotational area here corresponds to the curvature of the spherical region. The conveying elements 5b are further positioned at the rotor body 5a such that the center of the spherical rotational area and the center of the spherical section 2a substantially coincide with the pivot point of the bearing 8. This embodiment of the rotor 5 and the fluid channel 2 makes it possible that a minimal/minimum distance between the rotor 5 and the channel wall 2b also remains constant on a tilting of the rotor 5 and prevents the rotor 5 from contacting the channel wall 2b and the arising of damage to the rotor 5 or to the channel wall 2b or the impairment of the function of the blood pump 1 on the tilting of the rotor 5.

[0070] A position of the conveying elements 5b is shown in FIG. 6 with a maximum possible tilt of the rotor 5 about an axis orthogonal to the axis of rotation 7 by a small angle phi with respect to the axis of rotation 7. In this shown case, the front region of the rotor 5 at the inlet side nestles at the channel wall 2b. However, due to the spherical arrangement of the conveying elements 5b in the spherical region 2a, no contact of the rotor 5, in particular of the conveying elements 5b, with the channel wall 2b takes place. Damage is thus prevented by the design in accordance with the invention of the rotor 5 and the fluid channel 2 and an impairment of the function of the blood pump 1 caused thereby is avoided.

[0071] To enable a nestling over a larger region, both the rotor 5 and/or the channel wall 2b can be provided with a chamfer in this region. Hydraulically effective structures are furthermore possible in the region of the rotor-channel wall contact that bound a deflection of the rotor 5 or provide an additional hemocompatible support or that amplify or define the arising prerotation of the flow in the inlet region 3.

[0072] FIG. 7 shows a blood pump 1 in accordance with a sixth embodiment in a longitudinal sectional view. The blood pump 1 is set up like the blood pump in FIGS. 5 and 6 and only differs by the presence of conveying elements 5f extended into the ring volute 12. The conveying elements 5f are, like the other conveying elements 5b, at least partially arranged in the spherical region 2a of the fluid channel 2 at an outer side of the rotor body 5a. The conveying elements 5f are furthermore arranged toward the volute 12 at the rotor body 5a. An outer contour of the conveying elements 5f is formed substantially spherically in the regions of the extended conveying elements 5f that are substantially located in the spherical region 2a so that these regions of the conveying elements 5f also sweep over a spherical rotational area on a rotation of the rotor 5, whereby no contact of the rotor 5 with the channel wall 2 takes place in the spherical section 2a on a tilting of the rotor 5. The extended conveying elements 5f improve a flow of the blood from the fluid channel 2 into the ring volute 12 and further to the outlet region (not shown here) and support the change of the direction of flow in the ring volute 12 from a mixed radial and axial direction to a purely radial direction of flow.

[0073] FIG. 8 shows a blood pump 1 in accordance with a seventh embodiment in a longitudinal sectional view. The blood pump 1 in FIG. 8 is substantially set up like the blood pump of FIGS. 5 to 6 and only differs in the shape of the rotor body 5a. The rotor body 5a has a conical region 5g at the inlet side that tapers toward the inlet region and that is disposed in parallel with the channel wall 2b on a maximum possible tilt of the rotor 5. This improves a nestling of the rotor 5 in the region of the blood pump 1 at the inlet side and additionally reduces the risk of damage to the rotor 5 or to the channel wall 2b in the case of a tilting of the rotor 5.

[0074] FIG. 9 shows a blood pump 1 in accordance with an eighth embodiment in a longitudinal sectional view. The blood pump 1 in FIG. 8 is substantially set up like the blood pump in FIG. 8 and only differs in the shape of the volute 12. The blood pump 1 has a semi-axial volute 12 that conducts the blood both radially axially up to the outlet region 4 in a very compact manner. In the semi-axial volute 12, the conveyed blood is not subjected to any change or is only subjected to a change of the direction of flow very slowly from a mixed radial and axial direction to a purely radial direction of flow in the outlet region. This additionally improves the flow of the conveyed blood up to the outlet region 4 compared with a radial ring volume such as is shown, for example, in FIG. 8. The very slow change of direction of flow is typically advantageous for an optimal conversion of the radial and axial components of the flow of the fluid generated by operation of the rotor 5 into an increased change in fluid pressure. In particularly, it is advantageous to adapt the radial and axial components of the volute 12 to fit the direction of flow of the fluid coming from the spherical section 2a to the direction of flow into which the fluid is forced within the volute 12. The axial portion and the radial portion of the volute 12 in an inlet section of the volute are chosen such that a 3-dimensional volute flow vector at a radial angle does not deviate more than 30° from a 3-dimensional fluid flow vector of the fluid entering the volute at that radial angle when the rotor 5 is operated at a design point. The 3-dimensional volute flow vector is determined by a direction of flow that the volute forces the fluid into. This can, for example, be given by the surface normal of the fluid channel within the inlet section of the volute 12 at the radial angle. The radial angle is defined as an angle within a plane perpendicular to the axis of rotation 7 relative to a reference axis within that plane. The design point is defined by a chosen parameter or a chosen set of parameters characterizing an operation condition of the rotor 5 for which the rotor 5 is designed. In one example, the design point is defined by a number of RPM that the blood pump 1 is expected to be operated in on average. However, other definitions of the design point are also possible. Inlet sections of the volute 12 are all those parts of the volute that directly interface with the spherical section 2a of the blood pump 1. The relationship between volute flow vector and fluid flow vector will be explained in the following in more detail with reference to FIG. 10a and FIG. 10b.

[0075] FIG. 10a shows a simplified cross-sectional view of the blood pump 1 of FIG. 9 perpendicular to the axis of rotation 7. The cross-sectional view shows an interface between the volute 12 and the spherical section 2a. FIG. 10b shows a simplified side view of the blood pump 1 of FIG. 9.

[0076] The cross-sectional view shows a volute inlet 12.2 of the volute 12 that forms an opening through which fluid can flow from the spherical section 2a into the volute 12. A solid line indicates the volute inlet 12.2, which has the form of a channel expanding radially over an angle ϕ in the plane of the cross-section. The width of the channel in this plane is constant in the shown example, however, can expand with an increasing angle ϕ in the counter-clockwise direction. A dashed line indicates a projection of the center line 12.1 of the volute 12 in the plane of the cross-section. Please note that the actual center line changes its position along the pump axis (downward direction in FIG. 10b) over the angle ϕ. The radial angle ϕ is indicated for an arbitrarily defined coordinate system given by axes Cx and Cy. For the radial angle ϕ, a 3-dimensional volute flow vector v is indicated that corresponds to the surface normal of the fluid channel within the volute 12 facing downstream from the rotor 5. The same arrow that is indicating the 3-dimensional volute flow vector v also indicates the 3-dimensional fluid flow vector f, which are approximately identical with respect to their components lying within the plane spanned by the coordinate axes Cx and Cy. While the projection of center line 12.1 is shown as a circle centered in the volute inlet, the actual centerline projection may wander towards the outer edge of the volute inlet indicated by the solid line with an increasing angle ϕ in the counter-clockwise direction. This is equivalent with the view shown in FIG. 9, where the center line at the right side of the volute as shown in FIG. 9 is close to the center of the volute inlet, whereas the center lien is axially further downward and to the left of the volute inlet.

[0077] In the side view of FIG. 10b, also those components of vector v and vector f are visible which are parallel to the axis of rotation 7. In the example of FIGS. 10a and 10b, the 3-dimensional fluid flow vector f of the fluid entering the volute 12 at the radial angle ϕ is approximately identical to the 3-dimensional volute flow vector v. However, in other examples, there is can be deviation of up to 30° between those vectors. In the example, the comparison of vector v and f is shown for only one radial angle. However, the condition is fulfilled for all radial angles. Also, in the example of FIG. 10a and FIG. 10b, only a single fluid flow vector f is shown. However, in some examples, the fluid flow vector f is different along the opening 12.2 for the same radial angle. Nevertheless, each of those vectors should not deviate from the volute flow vector by more than 30°.

[0078] As is visible in FIG. 10a and FIG. 10b, the volute 12 expands continuously radially and axially towards the fluid outlet 4 downstream from the rotor 5. In other words, the volute 12 forms a spiral around the axis of rotation 7, which expands along the axis of rotation 7 and whose radius is continuously increasing downstream from the rotor 5. In some examples, the expansion only takes place downstream from the rotor 5. In other examples, in addition, the volute 12 has a diameter that continuously increases downstream from the rotor 5. In yet other examples, additionally or alternatively, a pitch of the volute in axial direction increases continuously downstream from the rotor 5. The different configurations of the volute just described typically lead to a reduction in flow separation, backflow and the formation of uncontrolled vortex streets, which reduces blood-damaging and thrombogenic influences.

[0079] FIG. 11 shows a blood pump 1 in accordance with a ninth embodiment. The blood pump 1 comprises a fluid channel 2 with an inlet region 3 and a spherical section similar to the blood pumps according to the previously described embodiments. The fluid channel 2 extends primarily along an axis of rotation 7. Furthermore, the blood pump 1 comprises a volute 12 in proximity to a fluid outlet 4, wherein an end piece 13 is mounted in fluid connection with the fluid outlet 4 of the volute 12. The end piece 13 comprises a diffuser with an opening angle in a range between 5° and 20°. The opening angle of the diffuser is given with respect to a center line 7′ of the fluid channel 2 within the diffuser. However, the diffuser can alternatively also be present in the volute 12 itself.

[0080] FIG. 12 shows a blood pump 1 in accordance with a tenth embodiment. The blood pump 1 comprises a fluid channel 2 with an inlet region 3 and a spherical section similar to the blood pumps according to the previously described embodiments. The fluid channel 2 extends primarily along an axis of rotation 7. Furthermore, the blood pump 1 comprises a volute 12 in proximity to a fluid outlet 4, wherein an end piece 13 is mounted in fluid connection with the fluid outlet 4 of the volute 12. The end piece 13 is pivotable around an axis perpendicular to the axis of rotation 7 and, as a result, allows to adapt a position of the fluid outlet 4 of the fluid channel 2 according to the needs of the patient.

[0081] The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Additionally, the illustrations are merely representational and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.

[0082] One or more embodiments of the disclosure may be referred to herein, individually and/or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any particular invention or inventive concept. Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.

[0083] The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description. While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.