Blood pump

Abstract

The present invention relates to an intravascular blood pump for percutaneous insertion into a blood vessel of a patient. The blood pump includes a pump housing having a blood flow inlet and a blood flow outlet and an impeller disposed in the pump housing to be rotatable about a rotation axis. The impeller has blades sized and shaped for delivering blood from the blood flow inlet to the blood flow outlet. The blood pump includes a drive unit for rotating an impeller, which includes a plurality of posts arranged about an axis of rotation. Each of the posts has an impeller-side end directed toward the impeller, the impeller-side end having a front surface facing the impeller. A coil winding is disposed around each of the posts to generate magnetic field lines through a front surface of each post and is controllable to generate a rotating magnetic field, the impeller comprising a magnetic structure arranged to interact with the rotating magnetic field to cause the impeller to rotate. The front surface of the at least one post includes a concave surface in which the front surface is inclined downward toward a central region of the front surface to concentrate at least part of the magnetic field lines passing through the front surface.

Description

[0001] Divisional application

[0002] This application is a divisional application of the patent application with the international application date of September 1, 2020, application number 202080061726.X, the date of entering the Chinese national phase on March 2, 2022, and the invention name being "Blood Pump". Technical Field

[0003] The present invention relates to an intravascular blood pump, in particular to an intravascular blood pump for percutaneously inserting into a patient's blood vessel to support blood flow in the patient's blood vessel. The blood pump has an improved driving unit. Background Art

[0004] Different types of blood pumps are known, such as axial-flow blood pumps, centrifugal (i.e., radial) blood pumps, or hybrid blood pumps in which blood flow is induced by both axial and radial forces. An intravascular blood pump is inserted into a patient's blood vessel, such as the aorta, by means of a catheter. A blood pump typically comprises a pump housing having a blood flow inlet and a blood flow outlet connected by a passageway. To induce blood flow along the passageway from the blood flow inlet to the blood flow outlet, an impeller or rotor is rotatably supported within the pump housing, wherein the impeller is provided with blades for conveying blood.

[0005] A blood pump is typically driven by a drive unit, which may be an electric motor. For example, WO 2017 / 162619A1 discloses an intravascular blood pump having an impeller magnetically coupled to an electric motor. The impeller includes a magnet arranged adjacent to an electromagnetic region in the electric motor. Due to the attractive force between the magnets in the impeller and the electromagnetic region in the electric motor, the rotation of the electric motor is transmitted to the impeller. Specifically, the drive unit includes a plurality of stator poles arranged around the rotation axis of the impeller, and each pole carries a coil winding and serves as a magnetic core. A control unit sequentially supplies voltage to the coil winding to generate a rotating magnetic field, which causes the magnetically coupled impeller to rotate.

[0006] More specifically, the intravascular blood pump disclosed in WO 2017 / 162619 A1 includes a pump housing with a blood flow inlet and a blood flow outlet, an impeller, and a drive unit for rotating the impeller. As the impeller rotates about a rotation axis within the pump housing, blood is transported from the blood flow inlet to the blood flow outlet by the impeller's blades. The drive unit comprises six posts and a backplate connecting the rear ends of the posts, which serves as a magnetic yoke. When viewed in a plane perpendicular to the rotation axis, the posts are arranged in a circular pattern around the rotation axis, with each post having a longitudinal axis parallel to the rotation axis. Each post has a stem and a head portion angled at the end of the stem facing the impeller. The head portion extends radially beyond the stem to form a shoulder that serves as an axial stop for the coil windings arranged around each post. A control unit sequentially supplies voltage to the coil windings to generate a rotating magnetic field. The impeller includes a magnetic structure that interacts with the rotating magnetic field, causing the impeller to rotate with it.

[0007] In operation, adjacent poles may have different magnetisations. As a result, the magnetic flux passing through the poles tends to flow between those adjacent poles and avoid the impeller. Such magnetic flux is lost for generating torque. A disadvantage of the prior art is that the head portions extending radially beyond the rod are located at a particularly small distance from each other. Consequently, there is a considerable parasitic magnetic flux between the head portions, which is lost for generating torque. Although this parasitic flux could be counteracted by placing magnetic insulating material, such as magnets, between the head portions, the available space would be very limited and the polarisation of the magnets would have to be changed periodically to achieve reasonable insulation, which is difficult. One object of the present invention is to improve the drive unit in this respect. Summary of the Invention

[0008] The blood pump of the present invention may correspond to the blood pump described above. Thus, it may be an axial-flow blood pump or a diagonal blood pump that pumps partially axially and partially radially (the diameter of a purely centrifugal blood pump is generally too large for intravascular applications). However, according to one aspect of the invention, the front surface of the impeller-side end of at least one column, preferably of each column, comprises a concave surface in which the front surface slopes downwardly toward a central region of the front surface in order to concentrate at least part of the magnetic field lines passing through the front surface.

[0009] The magnetic field lines of the magnetic flux flowing from and into the surface of a component made of magnetic material extend perpendicular to that surface, i.e., they flow perpendicularly out of and into the plane of the surface. By providing the front surface of the pillar with a concave surface, i.e., a depression in which the front surface slopes downward toward the center of the front surface, the magnetic field lines entering and leaving the pillar via the front surface are forced to run closer together toward the central axis of the pillar. Since the magnetic field lines never cross one another, they are concentrated in front of the impeller-side end of the pillar and directed as a beam toward the impeller. This reduces parasitic flux between adjacent pillars.

[0010] The inclination of the concavity is less than 90° relative to the surface plane, preferably between 0° and 30°.

[0011] Preferably, the concavity extends to the periphery of the front surface. In other words, the concavity can begin at the outer edge of the front surface. This has the effect that the outermost magnetic field lines are also affected by the inclination of the concavity. The outermost magnetic field lines are those that tend most toward the adjacent pillars. Therefore, the concavity is most effective if it extends to the periphery of the front surface of the pillars.

[0012] It may be sufficient for the concavity to extend to the periphery of the front surface of a column on at least two, preferably exactly two, opposite sides of the front surface, i.e., on those sides closest to the adjacent columns. This may be advantageous, in particular, when the columns are cylindrical and therefore circular in cross-section. In other words, the risk of magnetic field lines joining adjacent columns is greatest when the columns are almost at a distance from one another. Therefore, it is sufficiently effective if the concavity extends to the periphery of the front surface of a column only on the two sides closest to the respective adjacent columns.

[0013] However, it is preferred that the outer perimeter of the concave surface coincide with the outer perimeter of the front surface. This way, due to the inclination of the concave surface, the outermost magnetic field lines are directed towards the center of the front surface along the entire outer perimeter of the front surface. As previously mentioned, the outermost magnetic field lines are the most likely to be diverted away from the impeller. Therefore, the concave surface is most effective if its outer perimeter coincides with the outer perimeter of the front surface.

[0014] The concave surface may have a flat bottom, as this is sufficient to direct the outermost magnetic field lines toward the center. Therefore, at least one region on the outer periphery of the concave surface is downwardly inclined. In this case, the concave surface may have straight, inclined sidewalls when viewed in a cross-sectional plane perpendicular to the front surface, or may have curved, inclined sidewalls when viewed in a cross-sectional plane perpendicular to the front surface. The curved, inclined sidewalls, with an increasing inclination toward the outer periphery of the concave surface, have the effect of maximizing the bundling effect of the outermost magnetic field lines.

[0015] Alternatively, the concave surface may have a curved cross section with a curved bottom, rather than a straight bottom, when viewed in a cross-sectional plane passing vertically through the front surface. In this way, the concentration effect on the magnetic field lines gradually decreases from the periphery of the concave surface to its center.

[0016] Alternatively, the concave surface can have a triangular cross-section when viewed in a cross-sectional plane passing vertically through the front surface. This increases the maximum depth of the concave surface. The deeper the concave surface, the greater the distance between the corresponding portion of the front surface of the post and the magnetic structure of the impeller, resulting in a reduction in the axial magnetic force generated between the post and the impeller. In particular, by reducing the axial magnetic force, the ratio between magnetic torque and axial magnetic force can be increased, an important metric in the development of magnetically driven intravascular blood pumps. This ratio is important because the amount of magnetic flux that can be generated is generally limited, and therefore it is desirable to use as much of it as possible to generate torque. The technical effect of the concave surface is to reduce the axial force acting on the rotor in the axial direction without sacrificing motor power, or, in other words, to increase motor power for the same total magnetic flux.

[0017] According to a preferred aspect of the present invention, this ratio can be further increased by sloping the front surface within the concave surface downwardly in a radially outward direction (in addition to sloping downwardly toward its central region). Thus, the radially inner region of the front surface within the concave surface protrudes axially relative to the axis of rotation than the radially outer region of the front surface within the concave surface. This also results in an increase in the maximum depth of the concave surface. As previously mentioned, the deeper the concave surface, the greater the distance between the corresponding portion of the front surface of the post and the magnetic structure of the impeller, resulting in a reduction in the axial magnetic force generated between the post and the impeller. Therefore, by sloping the front surface within the concave surface downwardly in a radially outward direction, the ratio between the magnetic torque and the axial magnetic force can be further increased.

[0018] Another important effect achieved by the radially outward downward tilt of the front surface, compared to a horizontal front surface, is that the bundle of concentrated magnetic field lines points radially outward, thus also affecting the magnetic structure of the impeller. This has a positive effect on the achievable magnetic torque. Similarly, this results in an improvement in the ratio between magnetic torque and axial magnetic force. Thus, the positive effect of the radially outward downward tilt of the front surface within the concave surface on the ratio between magnetic torque and axial magnetic force is twofold.

[0019] According to a preferred embodiment of the present invention, the combination of the inclination of the front surface of the concave surface in both the central and radially outward directions results in the concave surface opening toward a side surface of the post, i.e., toward a side surface radially outward relative to the axis of rotation. Preferably, the post has a triangular cross-section with three side surfaces, one of which is radially outward relative to the axis of rotation compared to the other two side surfaces. In this case, the concave surface opens toward the side surface radially outward of the post.

[0020] In all the aforementioned variants, the maximum depth of the concavity may preferably be between 0.05 mm and 0.3 mm.

[0021] According to another aspect of the invention, the impeller-side ends of the pillars do not extend radially beyond the impeller-side ends of the respective coil windings arranged around the pillars, wherein the term "radially" relates to a direction transverse to, and preferably perpendicular to, the longitudinal axis of the respective pillar. In other words, the pillars do not have a distinct head portion. Instead, the pillars preferably have a constant cross-section, at least in the region of their impeller-side ends, and more preferably along their entire length.

[0022] The advantage of the poles without head sections is that the magnetic losses due to parasitic fluxes between adjacent poles are reduced due to the greater distance between the poles. Compared to the pump described in WO 2017 / 162619 A1, in which the impeller-side ends of the poles radially extend beyond the impeller-side ends of the corresponding coil windings, the result is also an increase in the ratio between the achievable magnetic torque and the axial magnetic force between the drive unit and the impeller.

[0023] According to another aspect of the invention, the columns may each comprise a soft magnetic material which is discontinuous in a cross section transverse to, preferably perpendicular to, the longitudinal axis of the respective column, said axis preferably being parallel to the axis of rotation, as described in further detail in WO 2019 / 057636A1. "Discontinuous" in the sense of the present invention means that when viewed in any cross section transverse to the longitudinal axis, the soft magnetic material is interrupted, separated, crossed, etc. by insulating or other material or gaps to form strictly separated areas of soft magnetic material or areas which are interrupted but connected at different locations. In other words, the soft magnetic material of the column is discontinuous in a cross section transverse to, preferably perpendicular to, the direction of the magnetic flux caused by the respective coil windings in the column. Providing discontinuous soft magnetic material in a cross-sectional plane transverse to the direction of the magnetic flux reduces eddy currents. This further improves the effectiveness of the intravascular blood pump.

[0024] Preferably, at least one weld is provided on the surface of the discontinuous soft magnetic material, connecting at least one discontinuity in electrical conductivity within the discontinuous soft magnetic material. The weld facilitates the fabrication of a magnetic core, or a portion thereof, from the discontinuous soft magnetic material. Specifically, when separating a magnetic core or a core leg from a larger workpiece of discontinuous soft magnetic material, the discontinuous soft magnetic material may delaminate or otherwise lose its integrity due to machining forces exerted on the workpiece during the separation process. This is particularly critical due to the very small size of the magnetic core, and in particular the core leg, and can even occur when electrical discharge machining, in particular wire-cut electrical discharge machining, is used to separate the magnetic core or core leg from the workpiece. By applying the weld to the workpiece prior to the separation step, the mechanical stability of the discontinuous material is improved. When electrical discharge machining is used to cut the magnetic core or core leg from the workpiece, the flow of current to the cut portion is also improved. The weld or welds can subsequently form a portion of the magnetic core or leg. In particular, the impeller-side end surface of the leg, oriented transversely to the axis of rotation, exposes the discontinuous material. Thus, the weld or several welds may be arranged on the impeller-side surface of the column.

[0025] The drive unit may comprise a back plate connected to the rear end of the column. Like the column, the back plate may comprise a discontinuous soft magnetic material. Since the magnetic flux in the back plate is substantially transverse to or perpendicular to the axis of rotation, the soft magnetic material of the back plate may be made discontinuous in a cross section parallel to the axis of rotation. Alternatively, the column and the back plate may be made of a single piece of discontinuous soft magnetic material, such that the soft magnetic material of the back plate and the discontinuous soft magnetic material of the column are discontinuous in the same direction, preferably in a cross section perpendicular to the axis of rotation. Apart from this, substantially all the features and descriptions described above with respect to the discontinuous material of the column also apply to the back plate. However, the back plate may alternatively also be made of a continuous, i.e. solid, soft magnetic material.

[0026] According to a preferred embodiment of the drive unit comprising a backplate connecting the rear ends of the pillars, the material of at least one pillar is integral with the material of the middle area of ​​the backplate, wherein the middle area of ​​the backplate is the area of ​​the backplate located between the pillars. Preferably, all pillars are integrally connected to the backplate in this way. In other words, at least one pillar and the backplate, preferably the entire magnetic core of the drive unit, can be made of a single piece of material, which can also be called a monolith. The advantage of such a core is that the magnetic resistance at the transition between the pillars and the backplate can be minimized, thereby improving the magnetic flux. In addition, good mechanical stiffness can be achieved at the transition between the pillars and the backplate.

[0027] According to another preferred embodiment of the drive unit comprising a backplate to which the rear ends of the posts are connected, at least one post, preferably all posts, contacts the backplate with the rear end surface of the respective post. This has the advantage that the quality of the magnetic connection between the post and the backplate can be independent of the quality of the mechanical connection between the post and the backplate. For example, the post can be mechanically fixed in a corresponding recess in the backplate or fixed by glue provided around the rear end of the post. Thus, a good magnetic connection and thus a good magnetic flux can be achieved directly through the rear end surface of the post into the backplate without being forced to accept the limitations of the mechanical properties of the mechanical connection between the post and the backplate. Furthermore, with the rear end of the post received in a recess of appropriate size in the backplate, a magnetic circuit for transferring the magnetic flux is established, which can exist in addition to the circumferential transfer of the magnetic flux.

[0028] In this case, the posts can thus be magnetically connected to the backplate at corresponding contact planes on the backplate. This contact plane is preferably arranged parallel to the rear end surface of the posts. This contact plane is preferably arranged perpendicular to the axis of rotation. Preferably, the entire surface area of ​​the rear end surface of the posts contacts the backplate. This significantly reduces the magnetic resistance of the connection between the posts and the backplate. Unevenness of the contact planes of the rear end surface and the backplate is preferably such that a gap of no more than 10 μm is created.

[0029] The back plate, like the pillars, is preferably made of a soft magnetic material, such as electrical steel (magnetic steel) or other material suitable for closing a magnetic flux circuit, preferably cobalt steel. The diameter of the back plate can be in the range of 3 mm to 9 mm, for example 5 mm or 6 mm to 7 mm. The thickness of the back plate can be in the range of 0.5 mm to 2.5 mm, for example 1.5 mm. The outer diameter of the blood pump can be in the range of 4 mm to 10 mm, preferably 7 mm. The outer diameter of the arrangement of multiple pillars can be in the range of 3 mm to 8 mm, for example 4 mm to 7.5 mm, preferably 6.5 mm.

[0030] As mentioned above, the post is made of a soft magnetic material such as electrical steel (magnetic steel). The post and back plate can be made of the same material. Preferably, the magnetic core of the drive unit, including the post and back plate, is made of cobalt steel. The use of cobalt steel helps to reduce the size of the pump, especially the diameter. Of all magnetic steels, cobalt steel has the highest magnetic permeability and the highest magnetic saturation flux density, generating the most magnetic flux for the same amount of material.

[0031] The dimensions of the pillars, particularly their length and cross-sectional area, can vary and depend on various factors. In contrast to the dimensions of the blood pump (e.g., outer diameter), which are determined by its application, the dimensions of the pillars are determined by electromagnetic properties, which are adjusted to achieve the desired performance of the drive unit. One of these factors is the flux density to be achieved through the minimum cross-sectional area of ​​the pillars. The smaller the cross-sectional area, the higher the current required to achieve the desired magnetic flux. However, due to electrical resistance, higher currents generate more heat in the coil wires. More importantly, if the pillar cross-section is too small, the stator material will quickly become magnetically saturated. This means that while "thin" pillars are preferred to reduce overall size, this will require high currents and thus lead to undesirable heating. The heat generated in the wires also depends on the length and diameter of the wire used for the coil windings. Short wire lengths and large wire diameters are preferred to minimize winding losses (referred to as "copper losses" or "copper power losses" if copper wire is used, which is the typical case). In other words, if the wire diameter is small, then more heat is generated at the same current compared to a thicker wire, with a preferred wire diameter being, for example, 0.05 mm to 0.2 mm, such as 0.1 mm. Other factors that influence the column size and the performance of the drive unit are the number of windings of the coil and the outer diameter of the windings (i.e. the column comprising the windings). Many windings can be arranged in more than one layer around each column, for example, two or three layers can be provided. However, the higher the number of layers, the more heat will be generated due to the increased length of the wire in the outer layers with the larger winding diameter. The increased length of the wire may generate more heat due to the higher resistance of the long wire compared to a shorter wire. Therefore, a single layer of windings with a small winding diameter would be preferred, but due to the required power, more than one winding is usually provided.

[0032] A typical number of windings, which in turn depends on the length of the column, may be about 50 to about 150, for example 56 or 132. Independent of the number of windings, the coil windings are made of a conductive material, in particular a metal such as copper or silver. Silver may be preferred over copper because it has a resistance that is about 5% less than that of copper.

[0033] Preferably, at least one column, more preferably each column, has a triangular cross-section transverse to the longitudinal axis of the column. Preferably, the cross-section of the column is triangular over its entire length. Triangular columns can make high-proportion use of the available space in the pump casing, because such columns can be densely packed around the axis of rotation. Preferably, one side of the triangle faces away from the axis of rotation and is curved. The curved portion is curved around the axis of rotation. The radius of the curved portion preferably corresponds to the radius of the outer diameter defined by the plurality of columns arranged around the axis of rotation. By means of such a curved portion, it is possible to further increase the use of the interior space of the cylindrical pump casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above summary of the invention and the following detailed description will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the present disclosure, reference is made to the accompanying drawings. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the accompanying drawings. In the accompanying drawings:

[0035] Figure 1 A cross-sectional view of an intravascular blood pump is shown;

[0036] Figure 2 A cross-sectional view showing a first embodiment of a drive unit-impeller arrangement;

[0037] Figure 3A and Figure 3B Shown according to Figure 1 and Figure 2 A side view and a perspective view of the magnetic core of the drive unit of the arrangement of the drive unit-impeller;

[0038] Figure 4 Schematically shows Figure 3A and Figure 3B The windings of the six legs of the magnetic core;

[0039] 5A to 5D shows side views of the impeller-side end of a column according to four different embodiments;

[0040] Figure 6A The perspective view shows the Figure 2 The drive unit - the spacer for the arrangement of the impeller;

[0041] Figure 6B Shown Figure 3A A front view of a spacer;

[0042] Figure 6C Shown Figure 3A and Figure 3B a side view of a spacer;

[0043] Figure 7A Shown is a Figure 2 A perspective view of the first back panel with an opening for arranging the drive unit column;

[0044] Figure 7B Shows no Figure 2 A perspective view of the second back panel with an opening for arranging the drive unit column;

[0045] Figure 7C Shown include Figure 7A The first layer and Figure 7B a cross-sectional view of the assembled backplane of the second layer;

[0046] Figures 8A to 8Dshows the further manufacture according to Figure 2 The arrangement of the drive unit column is an intermediate product of the manufacturing stage;

[0047] Figures 9A to 9C Shown according to Figure 5C Welding parts on intermediate products;

[0048] Figure 10 Shown from the Figures 8A to 9C A perspective view of the column from which the intermediate product prepared is separated;

[0049] Figure 11 Shown Figure 9A a front view of the intermediate product on a plane having two weld seams and two cross sections of a column to be cut out of the intermediate product;

[0050] Figure 12 A front view of the end surface of the column with the weld is shown;

[0051] Figure 13 A cross-sectional view showing a second embodiment of a drive unit-impeller arrangement;

[0052] Figures 14A to 14C shows the manufacturing method for Figure 13 The step of forming an integrated magnetic core of a drive unit; and

[0053] Figures 15A to 15C Shown in the following 14A to 14C One or more welds may be provided on the surface of the manufactured integral magnetic core. DETAILED DESCRIPTION

[0054] refer to Figure 1 , which shows a cross-sectional view of a blood pump 1. The blood pump 1 comprises a pump housing 2 having a blood flow inlet 21 and a blood flow outlet 22. The blood pump 1 is designed as an intravascular blood pump, also known as a catheter pump, and is arranged into a patient's blood vessel by means of a catheter 25. The blood flow inlet 21 is at the end of a flexible sleeve 23, which can be placed through a heart valve, such as the aortic valve, during use. The blood flow outlet 22 is located in a side surface of the pump housing 2 and can be placed in a heart vessel, such as the aorta. The blood pump 1 is electrically connected to an electrical wire 26, wherein the electrical wire 26 extends through the catheter 25 to supply power to the blood pump 1 so as to drive the pump 1 by means of a drive unit 4, as explained in more detail below.

[0055] If the blood pump 1 is intended for long-term use, i.e., when the blood pump 1 is implanted in a patient for weeks or even months, it is preferably supplied with power by means of a battery. This allows the patient to be mobile, since the patient is not connected to a base station by a cable. The battery can be carried by the patient and can supply power to the blood pump 1, for example, wirelessly.

[0056] Blood is conveyed along a passage 24 connecting a blood flow inlet 21 and a blood flow outlet 22 (arrows indicate blood flow). Impeller 3 is configured to convey blood along passage 24 and is rotatably mounted within pump housing 2 about a rotation axis 10 by means of a first bearing 11 and a second bearing 12. Rotation axis 10 is preferably the longitudinal axis of impeller 3. In this embodiment, both bearings 11 and 12 are contact-type bearings. However, at least one of bearings 11 and 12 may be a non-contact bearing, such as a magnetic bearing or a hydrodynamic bearing. First bearing 11 is a pivot bearing having a spherical bearing surface that allows rotational motion and some degree of pivotal motion. Pin 15 is provided to form one of the bearing surfaces. Second bearing 12 is arranged in a support member 13 to stabilize the rotation of impeller 3. Support member 13 has at least one opening 14 for blood flow. Blades 31 are provided on impeller 3 to convey blood as impeller 3 rotates. Rotation of impeller 3 is induced by drive unit 4, which is magnetically coupled to a magnetic structure 32 at the end portion of impeller 3. The blood pump 1 shown is a hybrid blood pump, wherein the main flow direction is axial. It is understood that the blood pump 1 can also be a pure axial blood pump, depending on the arrangement of the impeller 3, in particular the blades 31.

[0057] The blood pump 1 comprises an impeller 3 and a drive unit 4. The drive unit 4 comprises a plurality of columns 40, for example six columns 40, only two of which are Figure 1 . The columns 40 are arranged parallel to the axis of rotation 10, more specifically, the longitudinal axis of each of the columns 40 is parallel to the axis of rotation 10. One end of the column 40 is arranged adjacent to the impeller. Coil windings 44 are arranged around the columns 40. The coil windings 44 are sequentially controlled by a control unit to generate a rotating magnetic field. Part of the control unit is a printed circuit board 6 connected to the electrical wires 26. The impeller has a magnetic structure 32, which is formed as a multi-piece magnet in this embodiment. The magnetic structure 32 is arranged at the end of the impeller 3 facing the drive unit 4. The magnetic structure 32 is arranged to interact with the rotating magnetic field to cause the impeller 3 to rotate around the axis of rotation 10.

[0058] To close the magnetic flux path, a backplate 50 is positioned at the end of the column 40 opposite the impeller side of the column. The column 40 serves as a magnetic core and is made of a suitable material, particularly a soft magnetic material such as steel or a suitable alloy, particularly cobalt steel. Similarly, the backplate 50 is made of a suitable soft magnetic material, such as cobalt steel. The backplate 50 enhances the magnetic flux, which allows the overall diameter of the blood pump 1 to be reduced, which is important for intravascular blood pumps. For the same purpose, a yoke 37, an additional impeller backplate, is positioned in the impeller 3 on the side of the magnetic structure 32 facing away from the drive unit 4. In this embodiment, the yoke 37 has a conical shape to guide blood flow along the impeller 3. The yoke 37 can also be made of cobalt steel. One or more flushing channels extending toward the central bearing 11 can be formed in the yoke 37 or the magnetic structure 32.

[0059] Figure 2 Shown for Figure 1 Cross-sectional view of a first preferred embodiment of a drive unit-impeller arrangement of a blood pump. Figure 2 As can be seen in FIG4 , the impeller-side ends 420 of the rods 40 do not extend radially beyond the windings 44. Instead, the cross-section of the rods 40 is constant in the direction of the longitudinal axis LA of the rods 40. This prevents the rods 40 from coming close to one another, as this would cause partial magnetic short-circuits and thus reduce the power of the motor of the blood pump.

[0060] according to Figure 2 The drive unit 4 may include at least two pillars 40. The number of pillars is preferably a multiple of three, and thus can be three, nine, or twelve. Alternatively, the number of pillars 40 can be a multiple of two, such as two, four, six, eight, ten, or twelve. A greater number of pillars 40 may be possible. The number of pillars 40 is preferably six. Due to the cross-sectional view, only two pillars 40 are visible. The pillars 40 and the back plate 50 form the magnetic core 400 of the drive unit 4, which can have a diameter of less than 10 mm.

[0061] As shown, the column 40 can be composed of a discontinuous soft magnetic material that is discontinuous in electrical conductivity. The discontinuous soft magnetic material includes a plurality of sheets 85 made of ferromagnetic material and stacked one on top of the other. The stacking direction is arranged in the direction of the longitudinal axis LA of the column 40 and is indicated by the arrow DL. As shown, the column 40 is arranged parallel to the rotation axis 10.

[0062] The spacer 7 is provided around the column 40. It is made of a non-magnetic material and has the function of keeping the distance between the columns 40 constant at the impeller side end of the column 40. The spacer 7 is provided about Figures 6A to 6C The impeller-side end 424 of the coil winding 44 extends to the spacer 7. A back plate 50 is provided at the other end of the column 40. Figure 2In the embodiment shown, the back plate 50 has a recess for receiving the post 40 therein. More specifically, it includes a first layer 51 having an opening 511 for the rear end 450 of the post 40. The back plate 50 will be 7A to 7C Describe in further detail.

[0063] It is conceivable to realize embodiments of the blood pump 1 having any combination of the three features described above: the impeller-side ends 420 of the posts 40 do not extend radially beyond the impeller-side ends 424 of the windings 44, non-magnetically actuated spacers 7 are provided between the posts 40, and the back plate 50 has a recess for receiving the rear ends 450 of the posts 40.

[0064] Figure 3A and Figure 3B Shown according to Figure 1 and 2 The following are side and perspective views of the magnetic core 400 of the drive unit 4 of the drive unit-impeller arrangement. The legs 40 and back plate 50 of the magnetic core 400 are shown at a distance from the magnetic structure 32 of the impeller 3. As can be seen, the front surface 42 of each of the impeller-side ends 420 of the legs 40 is provided with a concave surface. In this particular embodiment, as in all the embodiments described below, the concave surface extends over the entire front surface 42, so that the outer periphery of the concave surface coincides with the outer periphery of the front surface 42.

[0065] Thus, the slope of the concave surface extends to the outer periphery of the front surface 42. When viewed in a cross-sectional plane passing vertically through the front surface 42, the concave surface has a triangular cross-section, which in the embodiment shown is perpendicular to the longitudinal axis of the corresponding column 40. This is different from the embodiment described in WO2017 / 162619A1, in which the front surface 42 of each column 40 is inclined so as to form together the tapered front side of the magnetic core 400. That is, in WO2017 / 162619A1, each column has a stem portion and a head portion inclined at the impeller-side end of the stem portion. In addition, those head portions, although inclined, may have their front surfaces provided with the aforementioned concave surface, in which the front surface is inclined downward toward the central area of ​​the front surface and has a triangular cross-section when viewed in a cross-sectional plane passing vertically through the front surface.

[0066] The downward inclination of the front surface 42 within this concavity towards the central region of the front surface serves to concentrate and thereby bundle the magnetic field lines passing through the front surface, as will be described below in conjunction with Figure 4Further explained. However, within the concave surface, the front surface 42 not only slopes downward toward the center of the front surface 42, but also slopes further downward radially outward relative to the axis of rotation 10. In other words, the radially inner region of the front surface 42 within the concave surface protrudes axially from the radially outer region of the front surface 42 within the concave surface. This radially outward downward slope has the effect of directing magnetic field lines toward the periphery of the impeller's magnetic structure 32, thereby increasing the lever arm for rotating the impeller 3 and, in turn, increasing torque. Therefore, the concave surface's slope, both toward the center of the front surface 42 and radially outward, results in the concave surface being open toward the side surfaces of the post 40 that lie radially outward relative to the axis of rotation for the post 40 having a triangular cross-section. Consequently, the maximum depth point of the front surface 42 is located at the outer periphery of the respective post 40 and may range from 0.05 mm to 0.3 mm, preferably from 0.1 mm to 0.2 mm, and most preferably approximately 0.2 mm.

[0067] Figure 4 The magnetic core 400 (eg Figure 3A and Figure 3B The six windings 40a, 40b of the magnetic core 400 (shown in FIG) are shown. To generate a rotating magnetic field, two aspects are important. First, some of the legs must be magnetized in the positive direction, while others must be magnetized in the negative direction, so that the magnetic field lines of the magnetic flux extend from the positively magnetized legs through the magnetic structure 32 of the impeller 3 into the negatively magnetized legs, and further back through the back plate 50 to the positively magnetized legs to generate a closed magnetic field. Second, the magnetization direction of the legs must change sequentially from one leg to another in the circumferential direction to pull the magnetic structure 32 of the impeller 3 to rotate about the rotation axis 10. To achieve this, adjacent legs are magnetized in opposite directions by flowing appropriately oriented currents through the coil windings 44 arranged around each leg 40. For example, the first leg can be magnetized positively, the adjacent second leg negatively, the adjacent third leg positively, the adjacent fourth leg negatively, and so on. However, in a preferred embodiment, there are always two adjacent poles magnetized in one direction to drag the magnetic structure 32 of the impeller 3, and only one immediately following pole is magnetized in the opposite direction. In the case of six poles, four poles 40b are magnetized in one direction and two poles 40a are magnetized in the opposite direction, as schematically shown for a winding of six poles. Figure 4 As shown. Figure 4 As can be further seen in FIG, the magnetic field lines 500 extending through the concave front surface 42 are concentrated by the inclined surfaces in the concavity, so that the magnetic field lines form a bundle. Thus, the risk of short circuits is minimized in the sense that the magnetic field lines 500 connect between adjacent pillars 40a and 40b.

[0068] 5A to 5DA side view of the impeller-side end 420 of a column according to four different embodiments is shown respectively. Figure 5A The embodiment shown corresponds to the embodiment described above with a concave surface having an outer periphery that coincides with the outer periphery of the front surface and having two inclined side walls 42a that, as described above, are both inclined downwardly toward the central area of ​​the front surface 42 and radially outwardly relative to the axis of rotation. Thus, when viewed in any cross-sectional plane passing vertically through the front surface 42, the concave surface has a triangular cross-section and is open radially outwardly of the column.

[0069] Figure 5B The embodiment shown corresponds essentially to Figure 5A , except that it has a flat bottom 42b. Thus, the concave triangular cross-section is limited radially inward of the column relative to the axis of rotation. Further radially outward, the cross-section becomes trapezoidal. Thus, bottom 42b is flat and parallel to the general plane of front surface 42, while sidewall 42a is a straight sidewall with an oppositely inclined orientation.

[0070] exist Figure 5C In the embodiment shown, the concave surface has curved, sloping sidewalls 42 a such that the slope of the concave surface is greatest at the periphery of the front surface 42 .

[0071] Figure 5D The embodiment shown is Figure 5B and 5C The embodiment shown is a combination of the above, i.e. the concave surface has a flat bottom 42b and curved, sloping sidewalls 42a.

[0072] Figures 6A to 6C The figure shows a perspective view, a front view, and a side view of a spacer 7, respectively. The spacer 7 generally has the form of a disk or wheel with a through-hole 75 in the center. The spacer 7 includes an opening 71 for each of the pillars. For an embodiment with six pillars 40, six openings 71 are provided as shown. Spacer spokes 72 are arranged between the openings 71. When a pillar 40 is inserted into an opening 71, the spacer spokes 72 maintain the distance between the pillars 40. Furthermore, the spacer 7 includes an outer ring 73 and an inner ring 74, which connect adjacent spacer spokes 72 and stabilize the spacer. The spacer 7 is made of titanium, a paramagnetic material that prevents magnetic short circuits when placed between the impeller-side ends 420 of the pillars 40. Titanium offers high mechanical strength, allowing for the manufacture of a spacer 7 with a small thickness. This is advantageous considering the required construction space. Furthermore, titanium has a low electrical conductivity, minimizing eddy current losses, and is easy to machine. However, any other non-magnetic material may also be used, as long as it is stable, can be machined with high precision, and does not readily conduct electricity. It is also possible to use diamagnetic materials, as they can resist external magnetic fields.

[0073] Figure 7AA perspective view of the first layer 51 of the back plate 50 is shown. The first layer 51 is generally in the shape of a disk or wheel with a hole 515 in the center. The first layer 51 includes openings 511 into which the rear ends 450 of the posts 40 are to be arranged. The first layer 51 includes spaced spokes 512 arranged between the openings 511. One function of the spaced spokes 512 is to keep the distance between the rear ends 450 of the posts 40 constant. Further, the first layer 51 includes an outer ring 513 and an inner ring 514 connecting the spaced spokes 512 at the radially outer end and the radially inner end of the opening 511, respectively. The first layer 51 can be made of a discontinuous soft magnetic material that is discontinuous in electrical conductivity. As Figure 7A As shown, it can include several ferromagnetic sheets 85, specifically three sheets. Sheets 85 are laminated with a non-conductive material to form a discontinuous soft magnetic material. The lamination direction DL is generally parallel to the sheets 85, and the main extension direction of the sheets defines the lamination plane. Within the backplate 50, the sheets 85 are perpendicular to the axis of rotation 10. A hole 515 is arranged in the center of the first layer 51. This hole serves to facilitate assembly of the first layer 51 with the second layer 52, for example, to center the first layer 51 and the second layer 52.

[0074] exist Figure 7B , a perspective view of the second layer 52 of the back plate 50 is shown. The second layer 52 essentially has the form of a disk with a hole 525 in the middle corresponding to the hole 515 in the first layer 51. The second layer 52 does not have any opening for the rear end of the column 40. Instead, the second layer 52 has a contact plane 526 facing the rear end 450 of the column 40. The rear end 450 of the column is in contact with the contact plane 526 of the second layer 52 of the back plate 50 in the assembled state of the drive unit to transfer magnetic flux between the rear end 450 of the column 40 and the back plate 50. Since all the rear ends 450 of the columns 40 are in contact with the contact plane 526, magnetic flux can be exchanged between the columns 40 and a magnetic zero point can be formed in the second layer 52. In order to enable this, the second layer 52 is made of a soft magnetic material. The soft magnetic material may be a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity and may include sheets 85 stacked together, similar to the structure described above with respect to the first layer 51. As an example, Figure 7B The three sheets 85 shown may form the second layer 52. In the second layer 52, the stacking direction D is perpendicular to the axis of rotation 10. The sheets 85 are ferromagnetic and electrically conductive, while the intermediate layers (not explicitly shown) between the sheets 85 are non-ferromagnetic and electrically non-conductive. This type of discontinuous soft magnetic material reduces eddy currents, which would otherwise be generated in greater quantities due to changes in magnetic flux. The hole 525 in the center of the second layer 52 facilitates assembly of the first layer 51 and the second layer 52, for example, by aligning the first and second layers 51, 52.

[0075] Figure 7CA cross-section of a back plate 50 is shown. It consists of a first layer 51 and a second layer 52, which are bonded to each other at their major surfaces with the greatest extension. The bond between the first and second layers 51, 52 of the back plate 50 can be established in the same manner as between the sheets 85 of the first and second layers 51, 52. The holes 515 of the first layer 51 and the holes 525 of the second layer 52 are aligned to center the first and second layers 51, 52. By stacking the first and second layers 51, 52, the opening 511 is closed at one end by the second layer 52, forming a recess 501 to accommodate the rear end 450 of the post 40. The bottom of the recess 501 forms a contact plane 526. When the post 40 is inserted into the recess 501, its rear end 450 contacts the contact plane 526. Furthermore, the position of the post 40 is secured by the spaced spokes 512, as well as the outer and inner rings 513, 514, which together surround each post 40. In this way, a magnetic connection is established between the second layer 52 and the rear end surface 45 of the post 40 at the contact plane 526, and in addition, a second magnetic connection is established between the post 40 and the above-mentioned surrounding portion of the first layer 51. However, the main part of the magnetic flux is transferred via the contact plane 526. Preferably, both the surface at the rear end 450 of the post 40 and the contact plane 526 have a predefined flatness. In this way, the gap between the surface 45 at the rear end 450 of the post 40 and the contact plane 526 can be kept below a certain value, preferably less than 10 μm. This improves the transfer of magnetic flux between the post 40 and the backplate 50. Preferably, no additional material is present between the surface 45 at the rear end 450 of the post 40 and the contact plane 526. In this embodiment of the invention, the transfer of magnetic flux via the surface 45 and the backplate 50 is independent of the way in which the post 40 is fastened to the backplate 50.

[0076] Figures 8A to 8D The preparation steps for producing column 40 are shown. Figure 8A A perspective view of a plate 8 made of a discontinuous soft magnetic material which is discontinuous in terms of electrical conductivity, also referred to as workpiece, is shown.

[0077] exist Figure 8A , the plate 8 is marked with a width W for cutting a workpiece rod 81 from the plate 8. The width W of the workpiece rod 81 is equal to the length of the column 40 to be manufactured from the workpiece rod 81. Figure 8A The enlarged view of the portion indicated by the rectangle R in Figure 8B Here, the stacked discontinuous sheets 85 of soft magnetic material can be seen. The stacking direction DL extends along the main plane of the plate 8 and thus forms the stacking plane.

[0078] Figure 8C A workpiece bar 81 is shown cut from a sheet 8 as separate pieces of discrete material. Figure 8C The enlarged view of the portion indicated by the rectangle R in Figure 8DThe sheet 85 of the workpiece bar 81 can be seen in this view.

[0079] Figure 9A Shown Figure 8C and Figure 8D The workpiece rod 81 forms the basis for the welding step in preparation for cutting the column 40 from the rod 81. Figure 9A , a plurality of cross sections 84 of the column 40 to be manufactured from the rod 81 are depicted in the side plane on the left. The column 40 is manufactured by cutting these cross sections 84 from the rod 81. Since the width W of the rod 81 corresponds to the length of the column 40, the side surfaces 811 and 812 of the rod 81 become the end surfaces at the impeller-side end 420 and the rear end 450 of the column 40.

[0080] Figure 9B The next preparation step before cutting out the column 40 is shown. Two welds 82 and 83 are welded at a distance from each other on the side 811 of the rod 81 and pass through each of the cross-sections 84 to be cut out of the column 40. Welds 82 and 83 extend perpendicular to the lamination direction DL of the sheet 85. In this way, the sheets of discontinuous material are connected to each other. Instead of two welds, a single weld can be provided. In addition, a similar weld can be provided on the opposite side 812 of the rod 81. The sheets 85 have a better mechanical connection to each other due to welds 82 and 83, and are also electrically connected. The latter has the advantage that current can flow from any location of the discontinuous soft magnetic material that is desired to become the column 40 to each location of the rod 81 that may be required for, for example, electrical discharge machining. In this way, electrical discharge machining is significantly facilitated. Moreover, because the cut column 40 does not delaminate, higher processing reliability is achieved. Preferably, laser welding is applied. It may be advantageous to apply welding power twice or more frequently to the same weld. The portion of the rod 81 indicated by the rectangle R is Figure 9C Shown enlarged.

[0081] therefore, Figure 9C A plurality of cross sections 84 of the column 40 are shown to be cut from the rod 81. The cross sections 84 have a substantially triangular shape. As shown, the corners may be rounded. Figure 9C The convex side 842 shown on the left side of the cross section 84 has a convex form. This type of cross section 84 is advantageous for fully utilizing the available construction space inside the cylindrical pump housing 2. The bisector of the cross section 84 at the corner 841 opposite the convex side 842 of the cross section 84 is aligned with the lamination direction DL. Thus, the sheet 85 extends symmetrically across the cross section 84.

[0082] Figure 10The column 40 is shown having been cut from the rod 81. As can be seen, welds 82 and 83 are still present on the surface 45 at the rear end 450 of the rod 81. The column 40 has a constant cross-section 84 along its entire length. If desired, the welds 82 and 83 can be deburred after the column 40 is cut. Simultaneously or in a subsequent step, a cross-section having a cross-section such as the following is cut on the surface of the opposite end of the column 40. 5A to 5D The concave surface may be formed in any of the configurations shown, or in a different configuration, which surface will later form the front surface 42 of the impeller-side end 420 of the post 40. Alternatively, the concave surface may be formed, for example by wire discharge machining, before providing the weld and cutting the post 40 from the rod 81.

[0083] Figure 11 Another arrangement of two sections 84 on the side 811 of the workpiece bar 81 is shown. Figures 9A to 9C In contrast to the workpiece rod 81 shown in FIG. Figure 11 The side surface 811 of the workpiece rod 81 has a size that allows two sections 84 to be arranged next to each other in a direction perpendicular to the stacking direction DL. The sections 84 are oriented relative to the stacking direction DL so that the bisector B of the angle of each section 84 opposite its respective convex side edge 842 is aligned with the stacking direction DL. This way of arranging the sections 84 along the rod 81 saves material. Less waste material is generated. It is conceivable to stack even more sections 84 of the column 40 in a direction perpendicular to the stacking direction DL, depending on the thickness of the rod 81 and the required cross-sectional dimensions of the column 40. Each of the welds 82 and 83 passes through each of the sections 84. The welds 82, 83 pass through the entire side surface 811 of the rod 81 in a direction perpendicular to the stacking direction DL. In this way, all sheets 85 of the discontinuous soft magnetic material of the rod 81 are connected to each other.

[0084] Figure 12 FIG. 8 shows an example of a column 40 cut from a welded rod 81, namely a front view of the rear end surface 45 of the column 40. Figure 12 As shown, a single weld 86 having a relatively large width, which may cover more than about one-third of the height of the triangular section 84, extends along the convex side 842 of the section 84. The weld 86 extends perpendicular to the lamination direction DL to connect all the sheets thereof. However, as Figure 11 The two welds shown are more preferred than a single weld.The bisector B of the corner 841 opposite the convex side 842 is again aligned with the lamination direction DL.

[0085] Figure 13 Shown for Figure 1 A second embodiment of the arrangement of the drive unit - impeller of the blood pump 1. Figure 2In the first embodiment shown in FIG, the front surface 42 of the impeller-side end 420 has a concave surface that tapers radially outward away from the magnetic structure 32 of the impeller 3. Furthermore, the impeller-side end 420 of the post 40 does not extend radially beyond the winding 44. Rather, the cross-section of the post 40 remains constant in the direction of the longitudinal axis LA of the post 40. This prevents the posts 40 from coming close together, as this would cause local magnetic short circuits and thus reduce the power of the blood pump's motor.

[0086] Similarly, according to Figure 13 The drive unit 4 may include at least two pillars 40. The number of pillars is preferably a multiple of three, and thus can be three, nine, or twelve. Alternatively, the number of pillars can be a multiple of two, such as two, four, six, eight, ten, or twelve. A greater number of pillars 40 is also possible. The number of pillars 40 is preferably six. Due to the cross-sectional view, only two pillars 40 are visible. The pillars 40 and the back plate 50 form the magnetic core 400 of the drive unit 4, which can have a diameter of less than 10 mm.

[0087] The second embodiment and Figure 2 The difference from the first embodiment shown in the figure lies in the different structure of the magnetic core. Here, the magnetic core 400 includes the magnetic components of the drive unit 4 as a single piece or block, the magnetic components being the column 40 and the back plate 50. The block is composed of a discontinuous soft magnetic material. The discontinuous soft magnetic material is discontinuous in terms of electrical conductivity. As shown in the figure, it includes a plurality of sheets 85 of ferromagnetic material, which are stacked together to form a structure such as Figure 14C The monolithic block 9 is shown with the lamination direction DL parallel to the axis of rotation 10 .

[0088] The coil winding 44 extends to the impeller-side end 420 of the column 40. This has the advantage that a magnetomotive force can be generated along the entire column 40. The magnetic core 400 includes a protrusion 401 that protrudes radially away from the column 40 at the rear end 450 of the column 40. This protrusion 401 forms a stop for the coil winding 44 toward the back plate 50. Because the integral magnetic core 400 connects the back plate 50 and the column 40 with high rigidity, spacers between the columns 40 at the impeller-side end 420 of the column can be omitted. The integral magnetic core 400 provides the advantage of achieving an optimal magnetic connection between the column 40 and the back plate 50. The magnetic core 400 can have a diameter of less than 10 mm.

[0089] 14A to 14C shows the manufacturing process for Figure 13 The arrangement of the drive unit - impeller of the magnetic core 400 of the drive unit 4 is shown in the steps. Figure 14AA cube-shaped monolith 9 is shown in perspective view, which forms a workpiece for manufacturing a magnetic core 400. The monolith 9 consists of a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity. It comprises sheets 85 oriented in a lamination direction DL extending along the main plane of the sheet 85. The sheets 85 are each bonded to their respective adjacent sheets by a bonding layer of non-conductive material, which is 14A to 14C Not explicitly shown.

[0090] Figure 14B The magnetic core 400 is shown in a semi-manufactured state after being machined from a cubic monolithic block 9 into a substantially cylindrical body 94. During this machining step, the protrusions 401 are manufactured. The reduced diameter sections 404 of the body 94, which form the outer peripheral surface of the legs 40 of the magnetic core 400, are manufactured to have a diameter corresponding to the outer diameter of the outermost convex side 842 of the legs 40, wherein the larger diameter section 405 will later form part of the back plate 50.

[0091] The body 94 is then further manufactured to produce Figure 14C . For this production step, electrical discharge machining can be used. For example, electrical discharge machining by wire cutting can be applied to produce gaps 49 separating the columns 40 from one another. Inside the gaps, space is provided for the coil windings 44. At the bottom of the gaps 49, a central region 59 of the integral backing plate 50 extends between the rear ends of the columns 40. The central region 59 is integral with the columns 40 and with the backing plate 50. Thus, the entire magnetic core is formed from a single block 9.

[0092] The lamination direction DL in the magnetic core 400 is such that it is parallel to the axis of rotation 10. It is acceptable for the lamination direction DL in the back plate 50 to be non-parallel with respect to the magnetic flux between the pillars 40 in the back plate 50. The magnetic core 400 can also be made of a wound soft magnetic sheet material separated by non-conductive layers. In this case, the lamination direction DL in the back plate 50 is always circumferential, which is advantageous for avoiding eddy currents in the magnetic flux in the back plate 50.

[0093] Figures 15A to 15C Shown in the following 14A to 14CHow one or more welds can be provided on the surface of the manufactured one-piece magnetic core. Accordingly, in the embodiment shown, three welds 82, 83 are provided on one side of the cubic monolith 9. The welds 82, 83 are welded at a distance from each other and through the cross section of the body 94 to be cut out from the monolith 9. The welds 82, 83 extend perpendicular to the stacking direction DL of the sheet 85. In this way, the sheets of discontinuous soft magnetic material are connected to each other. Instead of three welds, more welds or a single wider weld can be provided. In addition, similar welds can be provided on the opposite side of the monolith 9 (not shown). Instead of or in addition to the welds on the opposite side, one or more welds can be provided on the side surface of the monolith 9 at the level of the back plate 50 to completely or at least partially surround the back plate 50. The sheets 85 are better mechanically connected to each other due to the welds 82 and 83, and are also electrically connected. The advantage of the latter is that current can flow from any location in the discontinuous soft magnetic material to each location in the body 94 where electrical connections may be required, for example, for electrical discharge machining. This significantly facilitates electrical discharge machining. Furthermore, higher processing reliability is achieved because the back plate-pillar unit to be cut from the body 94 does not delaminate. Preferably, laser welding is applied. Applying welding power twice or more frequently to the same weld may be advantageous.

[0094] The body 94 is then machined to form Figure 15C . In this second embodiment, the concave surface in the front surface 42 of the column 40 has three inclined side walls instead of two, each of which has a downward slope toward the center of the front surface. The outer periphery of the concave surface coincides with the outer periphery of the front surface 42 of the column 40. However, the concave surface does not open to any side surface of the column 40. It is worth noting that, as Figure 14C The embodiment shown in FIG. 1 with only two inclined side walls is more efficient and is therefore preferred.

Claims

1. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump housing (2), the pump housing (2) having a blood flow inlet (21) and a blood flow outlet (22), an impeller (3) arranged in the pump housing (2) so as to be rotatable about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey blood from the blood flow inlet (21) to the blood flow outlet (22), a drive unit (4) for rotating the impeller (3), the drive unit (4) comprising a plurality of columns (40) arranged around the rotation axis (10), wherein each of the columns (40) has an impeller-side end (420) pointing toward the impeller (3), the impeller-side end (420) having a front surface (42) facing the impeller (3), and a coil winding (44) disposed about each of the posts (40) to generate magnetic field lines (500) passing through the front surface (42) of each of the posts (40), and the coil winding (44) being controllable to generate a rotating magnetic field, wherein the impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field to cause the impeller (3) to rotate, wherein the front surface (42) of at least one of the posts (40) comprises a concave surface in which the front surface (42) slopes downwardly towards a central region of the front surface (42), i.e., in a direction away from the impeller (3), so as to concentrate at least a portion of the magnetic field lines (500) passing through the front surface (42); and The concave surface has a flat bottom (42b).

2. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump housing (2), the pump housing (2) having a blood flow inlet (21) and a blood flow outlet (22), an impeller (3) arranged in the pump housing (2) so as to be rotatable about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey blood from the blood flow inlet (21) to the blood flow outlet (22), a drive unit (4) for rotating the impeller (3), the drive unit (4) comprising a plurality of columns (40) arranged around the rotation axis (10), wherein each of the columns (40) has an impeller-side end (420) pointing toward the impeller (3), the impeller-side end (420) having a front surface (42) facing the impeller (3), and a coil winding (44) disposed about each of the posts (40) to generate magnetic field lines (500) passing through the front surface (42) of each of the posts (40), and the coil winding (44) being controllable to generate a rotating magnetic field, wherein the impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field to cause the impeller (3) to rotate, wherein the front surface (42) of at least one of the posts (40) comprises a concave surface in which the front surface (42) slopes downwardly towards a central region of the front surface (42), i.e., in a direction away from the impeller (3), so as to concentrate at least a portion of the magnetic field lines (500) passing through the front surface (42); and Wherein, when viewed in a cross-sectional plane passing vertically through the front surface (42), the concave surface has a triangular cross-section.

3. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump housing (2), the pump housing (2) having a blood flow inlet (21) and a blood flow outlet (22), an impeller (3) arranged in the pump housing (2) so as to be rotatable about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey blood from the blood flow inlet (21) to the blood flow outlet (22), a drive unit (4) for rotating the impeller (3), the drive unit (4) comprising a plurality of columns (40) arranged around the rotation axis (10), wherein each of the columns (40) has an impeller-side end (420) pointing toward the impeller (3), the impeller-side end (420) having a front surface (42) facing the impeller (3), and a coil winding (44) disposed about each of the posts (40) to generate magnetic field lines (500) passing through the front surface (42) of each of the posts (40), and the coil winding (44) being controllable to generate a rotating magnetic field, wherein the impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field to cause the impeller (3) to rotate, wherein the front surface (42) of at least one of the posts (40) comprises a concave surface in which the front surface (42) slopes downwardly towards a central region of the front surface (42), i.e., in a direction away from the impeller (3), so as to concentrate at least a portion of the magnetic field lines (500) passing through the front surface (42); and wherein the concave surface is devoid of walls and is therefore open towards a first side surface of the at least one of the posts (40), wherein the first side surface is radially outward relative to the axis of rotation (10).

4. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein the concave surface extends to the periphery of the front surface (42).

5. An intravascular blood pump (1) according to claim 4, wherein the concave surface extends to the periphery of the front surface (42) at least on both sides of the front surface, and the two sides are closest to adjacent columns (40) among the multiple columns (40), or the concave surface extends to the periphery of the front surface (42) on both sides of the front surface, and the two sides are closest to adjacent columns (40) among the multiple columns (40).

6. The intravascular blood pump (1) according to claim 4, wherein the periphery of the concave surface coincides with the periphery of the front surface (42).

7. Intravascular blood pump (1) according to claim 2 or 3, wherein the concave surface has a flat bottom (42b).

8. An intravascular blood pump (1) according to claim 1 or 3, wherein the concave surface has rectilinearly inclined side walls (42a) when viewed in a cross-sectional plane passing vertically through the front surface (42).

9. The intravascular blood pump (1) according to claim 1 or 3, wherein the concave surface has curved and inclined side walls (42a) when viewed in a cross-sectional plane passing vertically through the front surface (42).

10. Intravascular blood pump (1) according to claim 2 or 3, wherein the concave surface has a curved cross section with a curved bottom when viewed in a sectional plane passing vertically through the front surface (42).

11. Intravascular blood pump (1) according to claim 2 or 3, wherein the concave surface has a triangular cross-section when viewed in a cross-sectional plane passing vertically through the front surface (42).

12. An intravascular blood pump (1) according to any one of claims 1 to 3, wherein in the concave surface, the front surface (42) is inclined downward in a radially outward direction relative to the rotation axis (10) so that a radially inner region of the front surface (42) in the concave surface protrudes axially from a radially outer region of the front surface (42) in the concave surface.

13. An intravascular blood pump (1) according to any one of claims 1-3, wherein the concave surface opens towards a first side surface of the at least one of the posts (40), wherein the first side surface is radially outward relative to the axis of rotation (10).

14. An intravascular blood pump (1) according to claim 3, wherein at least one of the columns (40) has a triangular cross-section with three side surfaces, the three side surfaces including the first side surface, wherein the first side surface is radially outward relative to the rotation axis (10) compared to the other two of the three side surfaces.

15. Intravascular blood pump (1) according to any one of claims 1 to 3, wherein the concavity has a maximum depth between 0.05 mm and 0.3 mm.

16. An intravascular blood pump (1) according to any one of claims 1 to 3, wherein the at least one of the columns (40) has a longitudinal axis (LA) and a constant cross-section at least in the impeller-side end region of the at least one of the columns (40), so that its impeller-side end (420) extends radially no further than the impeller-side end (424) of the coil winding (44) arranged around the at least one of the columns (40), wherein the term radial relates to a direction transverse to the longitudinal axis (LA).

17. An intravascular blood pump (1) according to any one of claims 1 to 3, wherein at least one of the columns comprises or consists of a discontinuous soft magnetic material, which is discontinuous in terms of conductivity in a cross section transverse to the longitudinal axis (LA) of the corresponding column (40) so as to provide at least one discontinuity in terms of conductivity in the discontinuous soft magnetic material.

18. An intravascular blood pump (1) according to claim 17, wherein at least one welding portion (82, 83, 86) is arranged on the surface (811) of the discontinuous soft magnetic material, and the welding portion (82, 83, 86) connects the at least one discontinuity in conductivity in the discontinuous soft magnetic material.

19. An intravascular blood pump (1) according to any one of claims 1 to 3, wherein each of the columns (40) has a rear end portion (450), wherein the drive unit (4) comprises a back plate (50) connecting the rear end portions (450) of the columns (40) and extending between the columns (40) in an intermediate region (59), wherein the material of at least one of the columns (40) is integral with the material of the intermediate region (59) of the back plate (50).

20. An intravascular blood pump (1) according to any one of claims 1 to 3, wherein each of the columns (40) has a rear end portion (450), wherein the drive unit (4) includes a back plate (50) connected to the rear end portions (450) of the columns (40), and wherein at least one of the rear end portions (450) of the columns (40) has a rear end surface (45) in contact with the back plate (50).

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