Blood pump

Abstract

To provide an intravascular blood pump for percutaneous insertion into a patient's blood vessel.SOLUTION: The blood pump comprises a drive unit 4 for rotating the impeller 3, the drive unit comprising a plurality of posts 40 arranged about the axis of rotation 10 and a back plate connecting rear ends thereof. The posts and the back plate together form a magnetic core of the drive unit. A coil winding is disposed around each of the posts. The coil windings are controllable so as to create a rotating magnetic field. The impeller 3 comprises a magnetic structure 32 arranged to interact with the rotating magnetic field so as to cause rotation of the impeller. The magnetic core 400 or a part of it comprises a discontinuous soft magnetic material which is discontinuous regarding electric conductivity in a cross- section. At least one weld is provided on a surface of the discontinuous soft magnetic material. The weld bridges at least one discontinuity regarding electric conductivity in the discontinuous soft magnetic material.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a blood pump for assisting blood flow within a patient's blood vessels, and in particular to an intravascular blood pump for percutaneous insertion into a patient's blood vessels. The blood pump has an improved drive unit. [Background technology]

[0002] Different types of blood pumps are known, such as axial-flow blood pumps, centrifugal (i.e., radial) blood pumps, or mixed-flow blood pumps, in which blood flow is induced by both axial and radial forces. Intravascular blood pumps are inserted into a patient's blood vessels, such as the aorta, using a catheter. Blood pumps typically include a pump casing having a blood inlet and a blood outlet connected by a passageway. An impeller or rotor is rotatably supported within the pump casing to induce blood flow along the passageway from the blood inlet to the blood outlet, and the impeller is provided with blades for transporting the blood.

[0003] Blood pumps are typically driven by a drive unit, which can be an electric motor. For example, U.S. Patent Application Publication No. 2011 / 0238172(A1) discloses an extracorporeal blood pump having an impeller that can be magnetically coupled to an electric motor. The impeller includes a magnet disposed adjacent to a magnet in the electric motor. Rotation of the motor is transmitted to the impeller due to the attractive force between the magnets in the impeller and the motor. To reduce the number of rotating parts, U.S. Patent Application Publication No. 2011 / 0238172(A1) also discloses the use of a rotating magnetic field. The drive unit includes multiple fixed pillars arranged around the rotation axis, each of which holds a wire coil winding and serves as a magnetic core. A control unit sequentially supplies voltage to the coil windings, creating the rotating magnetic field. To provide a sufficiently strong magnetic coupling, the magnetic force must be sufficiently high, which can be achieved by supplying a sufficiently high current to the drive unit or by providing a large magnet, but this leads to a large overall diameter of the blood pump.

[0004] EP 3222301 (B1) discloses a blood pump, in particular an intravascular blood pump, with a magnetic coupling between the drive unit and the impeller, which has a compact design and in particular a high ratio of pumping power to pump size, which results in sufficiently small external dimensions to allow the blood pump to be inserted transvascularly, transvenously, transarterially or transvalvularly, or even smaller for reasons of operation and convenience.

[0005] More specifically, the blood pump in EP 3222301 B1 comprises a pump casing having a blood inlet and a blood outlet, an impeller, and a drive unit for rotating the impeller. Rotation of the impeller within the pump casing about a rotation axis causes blood to be transported from the blood inlet to the blood outlet by the impeller blades. The drive unit includes a plurality of, preferably six, columns and a backplate connecting the rear ends of the columns and acting as a yoke. The columns and backplate form the magnetic core of the drive unit. When viewed in a plane perpendicular to the rotation axis, the columns are arranged in a circle around the rotation axis, and each column preferably has a longitudinal axis parallel to the rotation axis. Each column has a coil winding disposed therearound. The coil winding can be controlled in a coherent manner to generate a rotating magnetic field for driving the impeller. The impeller comprises a magnetic structure in the form of a magnet arranged to interact with the rotating magnetic field, thereby causing the impeller to follow its rotation. Summary of the Invention [Problem to be solved by the invention]

[0006] In unpublished European Patent Application No. 171919400, it has been proposed that discontinuous soft magnetic materials can be used for the magnetically active parts of the drive unit, particularly for the columns, in order to keep eddy current losses low. The discontinuous material can be, for example, a laminated material containing soft magnetic sheets. However, magnetically active parts of drive units made of such materials tend to disintegrate and break down in the layers between the sheets. Another problem arises with the possibility of fabricating such parts by electrical discharge machining: when such a workpiece is contacted at a specific location for electrical discharge machining, not all other locations of the material are in electrical contact with the contacted location. This can make electrical discharge machining difficult.

[0007] The present invention aims to facilitate the fabrication of drive units for intravascular blood pumps. [Means for solving the problem]

[0008] The blood pump of the present invention corresponds to the blood pump described above, as described in EP 3222301 B1. It can therefore be an axial-flow blood pump or a mixed-flow blood pump, pumping partly axially and partly radially (the diameter of a purely centrifugal blood pump is usually too large for intravascular applications). However, according to one aspect of the present invention, the magnetic core or parts thereof, in particular at least one of the pillars, comprises or consists of a discontinuous soft magnetic material that is discontinuous in electrical conductivity in a cross section transverse to the longitudinal axis of the respective pillar. At least one weld is provided on the surface of the discontinuous soft magnetic material, in particular on at least one pillar. The weld bridges the discontinuity in electrical conductivity in the discontinuous soft magnetic material.

[0009] Each of the pillars has a longitudinal axis. Preferably, the longitudinal axis of each pillar is parallel to the axis of rotation. Each pillar includes a soft magnetic material that is discontinuous in a cross section transverse to, preferably perpendicular to, the longitudinal axis of the respective pillar. In other words, the soft magnetic material of the pillar is discontinuous in a cross section transverse to, preferably perpendicular to, the direction of the magnetic flux generated by the respective coil winding in the pillar. By dividing or segmenting the soft magnetic material in the cross section, eddy currents in the pillar can be reduced or avoided, thereby reducing heat generation and energy consumption. Reducing energy consumption is particularly useful for long-term applications of blood pumps, where it is desirable for the blood pump to be battery-powered to provide patient mobility. Also, in long-term applications, the blood pump can be operated without purging, which is only possible when heat generation is low.

[0010] "Discontinuous" in the sense of this document means that the soft magnetic material is divided, separated, partitioned or similarly configured with insulating or other material or gaps, when viewed in any cross section transverse to the longitudinal axis, to form strictly separate areas of soft magnetic material or areas that are disconnected but connected at different locations.

[0011] Providing a discontinuous soft magnetic material in a cross-sectional plane transverse to the direction of the magnetic flux reduces eddy currents, and therefore heat generation and energy consumption, as explained above. To avoid significantly weakening the magnetic field compared to a continuous or full-body (i.e., solid) soft magnetic material, the total amount of soft magnetic material should be maximized while minimizing the continuous areas of soft magnetic material. This can be achieved by providing the soft magnetic material in the form of multiple sheets of soft magnetic material, such as electrical steel. In particular, the sheets can form a stack of sheets. The sheets are preferably electrically insulated from each other, for example, by providing an adhesive, lacquer, baked enamel, or the like, between adjacent ones of the sheets. Such a configuration can be described as "slotted." Compared to a full-body soft magnetic material, the amount of soft magnetic material is only slightly reduced, and the amount of insulating material is kept small, so that the magnetic field generated by the slotted pillar is substantially the same as that generated by a solid pillar. In other words, heat generation and energy consumption can be significantly reduced, while the magnetic field generated by the insulating material is only slightly lost.

[0012] The sheets preferably extend substantially parallel to the longitudinal axis of each pillar. In other words, the sheets may extend substantially parallel to the direction of magnetic flux, such that the pillars are discontinuous in cross sections transverse to or perpendicular to the direction of magnetic flux. It will be understood that the sheets may extend obliquely to the longitudinal axis of each pillar, so long as the soft magnetic material is discontinuous in cross sections transverse to the longitudinal axis. The sheets preferably have a thickness in the range of 25 μm to 1 mm, more preferably 50 μm to 450 μm, e.g., 200 μm.

[0013] It is commonly known to provide grooved soft magnetic materials, such as electrical steel, in electric motors to avoid or reduce eddy currents. However, this technique is applied to large devices, where the sheets typically have thicknesses in the range of about 500 μm or more. In small applications, such as the blood pump of the present invention, where one of the pillars typically has a diameter of the aforementioned order of magnitude and the power input is relatively low (e.g., up to 20 watts (W)), eddy currents and related problems were not anticipated. Surprisingly, despite the pillar's small diameter, providing grooved pillars can reduce eddy currents, and therefore heat generation and energy consumption. This is advantageous for the operation of blood pumps, which may be operated at high speeds of up to 50,000 revolutions per minute (rpm).

[0014] It will be understood that configurations other than the above-described grooved configuration for providing discontinuous soft magnetic material within the posts may also be possible. For example, instead of multiple sheets, multiple wires, fibers, posts, or other elongated elements may be provided to form each of the drive unit's posts. The wires or the like may be provided in the form of a bundle in which the wires are electrically insulated from one another, for example, by a coating surrounding each wire or an insulating matrix in which the wires are embedded, and may have various cross-sectional shapes, such as circular, round, rectangular, square, polygonal, etc. Similarly, particles of soft magnetic material, wire wool of soft magnetic material, or other sponge-like or porous structures may be provided, within which the spaces between areas of soft magnetic material contain an electrically insulating material, such as an adhesive, lacquer, a polymer matrix, or the like. Porous, and therefore discontinuous, structures of soft magnetic material may also be formed by sintering or pressing materials. In such structures, additional insulating materials may be omitted, since the insulating layer may automatically form due to the oxide layer resulting from oxidation of the soft magnetic material due to exposure to air.

[0015] While sheets or other structures of soft magnetic material can be uniformly formed, i.e., sheets within one or all of the columns can have the same thickness or wires with the same diameter, non-uniform configurations can be provided. For example, sheets can have varying thicknesses or wires can have varying diameters. More specifically, particularly with respect to stacks of sheets, one or more central sheets can have a greater thickness, while adjacent sheets toward the edges of the stack can have a smaller thickness. That is, the thickness of the sheets decreases from the center toward the edges of the stack, i.e., toward the outermost sheets of the stack. Similarly, one or more central wires within a wire bundle can have a larger diameter, while wires at the edges of the column can have a smaller diameter. That is, the diameter of the wires can decrease from the center toward the edges of the bundle, i.e., toward the outermost wires of the bundle. It can be advantageous to provide a larger continuous area of ​​soft magnetic material at the center of the column relative to a cross section transverse to the longitudinal axis of the column, i.e., to provide a relatively thicker sheet or wire at the center. This can be advantageous because it can enhance the magnetic flux through the center along the longitudinal axis of each pillar, and eddy currents in the center are less significant than eddy currents at the sides of the pillars. In other words, such a configuration can be advantageous because eddy currents in the side regions of the pillars are more significant and can be reduced by thin sheets or wires in the side regions.

[0016] Welds allow for easy fabrication of magnetic cores or portions thereof from discontinuous soft magnetic material. That is, when separating a magnetic core, or a column for a magnetic core, from a larger workpiece of discontinuous soft magnetic material, the discontinuous soft magnetic material may delaminate or otherwise lose its integrity due to the machining forces applied to the workpiece during the separation process. This is particularly significant due to the very small dimensions of the magnetic core, and particularly its column, and can occur even when electrical discharge machining, particularly wire-cut electrical discharge machining, is used to separate the magnetic core or its column from the workpiece. The use of welds applied to the workpiece prior to the separation step improves the mechanical stability of the discontinuous material. When electrical discharge machining is used to cut the magnetic core or column from the workpiece, it also improves current flow to the cutting location. The weld or welds can later form portions of the magnetic core or column.

[0017] Specifically, the impeller-facing end face of the post oriented transverse to the axis of rotation exposes discontinuous material. Thus, the weld or welds may be located on the impeller-facing surface of the post. Alternatively, or in addition, the weld or welds may be located on the rear end face of the post, or, if the core including the backplate acting as the yoke is integral with the workpiece as a monoblock, an additional weld or welds may be located on the rear end face of the backplate.

[0018] Preferably, the rear end face of at least one of the pillars, and preferably all of the pillars, is arranged substantially perpendicular to the longitudinal axis of at least one of the pillars. At least one of the pillars, and preferably all of the pillars, may further include a peripheral / circumferential surface disposed about and extending along the longitudinal axis of the pillar, the rear end face being provided at a rear longitudinal end of the peripheral surface, the rear end face facing away from the impeller. Preferably, the rear end face is substantially perpendicular to the peripheral surface.

[0019] Preferably, the entire surface of the core or of its pillar may be covered with a weld to bridge all soft magnetic components, such as sheets of discontinuous material present at the surface. Most preferably, all components of discontinuous material are bridged. Optimal fabrication can be achieved by bridging as many soft magnetic components of discontinuous material as possible.

[0020] Preferably, two welds are arranged at one end of at least one column, spaced apart from each other. These welds are preferably weld seams. Such weld seams are preferably arranged parallel to each other. In particular, the spaced apart seams can be welded onto the surface of the raw material or workpiece from which the column will be cut after welding.

[0021] Alternatively, or in addition, the weld or welds may extend onto the side of the pillar. Compared to welding the end face of the pillar, this alternative may generate less eddy currents because the weld surface does not cross the magnetic flux.

[0022] More than one of the at least one weld may be located on the same surface of at least one of the columns, whether that surface is a side or an end surface, or both. Additionally, in the alternative, the weld may at least partially surround a side surface of the column.

[0023] Preferably, the weld or welds are provided as a weld seam, which may have a smaller cross section compared to a weld covering the entire surface, which may cause the seam to generate a smaller amount of additional eddy currents.

[0024] Like the pillars, the backplate may include discontinuous soft magnetic material. Because the magnetic flux in the backplate is substantially transverse to or perpendicular to the axis of rotation, the soft magnetic material of the backplate is preferably discontinuous in a cross section parallel to the axis of rotation. An exception may be when the pillars and backplate are fabricated as a monoblock. Except for this, substantially all of the features and explanations described above regarding the discontinuous material of the pillars also apply to the backplate. For example, like the pillars, the backplate may be grooved, i.e., formed of multiple stacked sheets, with the backplate sheets preferably being electrically insulated from one another. The backplate sheets may extend substantially perpendicular to the pillar sheets. As explained above, eddy currents, and therefore heat generation and power consumption, may be reduced. However, the backplate may alternatively be formed of a continuous, i.e., solid, soft magnetic material.

[0025] The backplate, like the pillars, is preferably made of a soft magnetic material such as electric steel (magnetic steel) or other material suitable for closing a magnetic flux circuit, preferably cobalt steel. The diameter of the backplate can be in the range of 3 mm to 9 mm, e.g., 5 mm or 6 mm to 7 mm. The thickness of the backplate can be in the range of 0.5 mm to 2.5 mm, e.g., 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 multiple pillar configuration can be in the range of 3 mm to 8 mm, e.g., 4 mm to 7.5 mm, preferably 6.5 mm.

[0026] As mentioned above, the pole is made of a soft magnetic material such as electrical steel (magnetic steel). The pole and backplate can be made of the same material. Preferably, the drive unit, including the pole and backplate, is made of cobalt steel. The use of cobalt steel contributes to reducing the pump size, particularly the diameter. Because it has the highest magnetic permeability and highest saturation magnetic flux density of all magnetic steels, cobalt steel generates the largest amount of magnetic flux for the same amount of material used.

[0027] The dimensions of the pillar, particularly its length and cross-sectional area, vary and depend on various factors. The dimensions of the pillar, as opposed to the dimensions of the blood pump, e.g., its outer diameter, which depend on the application of the blood pump, are determined by the electromagnetic properties, which are adjusted to achieve the desired performance of the drive unit. One of the factors is the magnetic flux density to be achieved through the minimum cross-sectional area of ​​the pillar. The smaller the cross-sectional area, the higher the current required to achieve the desired magnetic flux. However, higher current generates more heat in the coil wire due to electrical resistance. This means that a "thin" pillar is preferable to reduce the overall size, but this requires a high current and therefore will generate undesirable heat. The heat generated in the wire also depends on the length and diameter of the wire used for the coil winding. To minimize winding losses (referred to as "copper losses" or "copper power losses" when copper wire is used, as is usually the case), a short wire length and a large wire diameter are preferred. In other words, a small wire diameter generates more heat than a thicker wire at the same current. A preferred wire diameter is 0.05 mm to 0.2 mm, e.g., 0.1 mm. Additional factors affecting the dimensions of the column and the performance of the drive unit are the number of windings in the coil and the outer diameter of the column including the windings. Multiple windings may be arranged around each column in more than one layer, e.g., two or three layers. However, the greater the number of layers, the more heat will be generated due to the increased length of wire in the outer layer with a larger winding diameter. The increased length of wire may generate more heat due to the higher resistance of long wire compared to shorter wire. Therefore, a single layer of winding with a small winding diameter may be preferred. A typical number of windings, which depends in turn on the length of the column, may be about 50 to about 150, e.g., 56 or 132. Regardless of the number of windings, the coil windings are made of an electrically conductive material, particularly a metal such as copper or silver. Silver may be preferred over copper because silver has an electrical resistivity that is approximately 5% less than that of copper.

[0028] Preferably, the pillar has a triangular cross section transverse to the axis of rotation, and the soft magnetic sheets of soft magnetic material are preferably oriented in or parallel to a plane passing through the bisector of the triangular cross section. This orientation has the advantage that the longest soft magnetic sheets are located in the center of the pillar. In the mounted state of the pillar, the bisector may extend through the radially innermost corner of the triangular cross section and preferably also through the axis of rotation.

[0029] In a further aspect of the invention, a method for fabricating a magnetic core, or part of a magnetic core, for a drive unit of an intravascular blood pump is proposed, comprising the following steps in order: providing a workpiece comprising or consisting of a discontinuous soft magnetic material, the soft magnetic material being discontinuous in electrical conductivity within a cross section of the workpiece, from which the magnetic core or part thereof is to be fabricated, providing a weld at the surface of the workpiece, whereby the weld bridges at least one discontinuity in electrical conductivity within the discontinuous soft magnetic material of the workpiece, and separating the magnetic core or part of the magnetic core from the workpiece after providing the weld.

[0030] At least a portion of the weld may remain on the post after separating the core, or a portion of the core, from the workpiece, after which, for example, laminated sheets of soft magnetic material may be held firmly together by the weld.

[0031] According to a preferred embodiment, the step of separating the magnetic core or a portion of the magnetic core from the workpiece includes separating at least one of the pillars from the workpiece by electric discharge machining (EDM), in particular by wire-cutting. Prior to machining the pillar from the workpiece of soft magnetic material, it is preferable to pre-cut one dimension of the workpiece to the length of the pillar, so that the pre-cut workpiece has the same outer dimension as the length of the pillar. A weld can be provided on the end surface defining the length of the pillar before the pillar is cut out. For example, one, or preferably two, weld seams can be spaced apart across each of the surfaces of the pre-cut workpiece that will later form the cross-sectional end faces of the pillar to be cut out from the workpiece. Preferably, all soft magnetic components of the discontinuous soft magnetic material of the pillar to be cut out are electrically connected by the weld. The weld seam can extend over the cross section of more than one pillar to be cut out from the workpiece. Specifically, the weld seam preferably extends from one end of the pre-cut workpiece to the opposite end of the pre-cut workpiece, and also extends across at least one cross-section of the post to be cut. More than one post may be machined from a single pre-cut workpiece. The cross-sections of the post to be cut may be appropriately distributed within the pre-cut material to utilize a high percentage of the material. As described above, the discontinuous soft magnetic material of the workpiece may be a laminated material including a stack of soft magnetic sheets. For example, the triangular cross-sections of two posts to be cut from the workpiece may be oriented so that the bisectors of the corners in each of the triangular cross-sections are aligned with the lamination plane of the soft magnetic material, the bisectors being spaced apart from each other, and the corners of the triangular cross-sections having the bisectors point in opposite directions. The above-described approach helps efficiently produce posts from the workpiece.

[0032] Preferably, for a triangular column, the weld or welds can be located along one side of the triangular cross section of the column, allowing the column to be mechanically stabilized from this side. In this way, the stacked sheets of soft magnetic material, preferably all sheets of the column, can be electrically connected by the welds.

[0033] Preferably, at least one weld is produced by laser welding. It is also possible to apply double laser welding, in which the weld location is welded at least once more. This can be useful, for example, to bridge a gap between two adjacent sheets of laminated soft magnetic material.

[0034] The cut-out core or core portion, in particular the cut-out pillar, may be deburred at at least one weld after separating the core or core portion from the workpiece, the burr possibly penetrating the electrical insulation.

[0035] The foregoing summary, as well as the following detailed description of the preferred embodiments, will be better understood when read in conjunction with the appended drawings. For purposes of illustrating the present disclosure, reference is made to the drawings. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the drawings. [Brief explanation of the drawings]

[0036] [Figure 1] 1 shows a cross-sectional view of a blood pump. [Figure 2] 1 shows a cross-sectional view of a preferred embodiment of a drive unit-impeller configuration. [Figure 3A] 3 shows a spacer for the drive unit-impeller arrangement according to FIG. 2 in a perspective view. FIG. [Figure 3B] 3B shows a front view of the spacer of FIG. 3A. [Figure 3C] 3C shows a side view of the spacer of FIGS. 3A and 3B. FIG. [Figure 4A] 3 shows a perspective view of the first layer of the backplate with openings for the posts of the drive units of the arrangement according to FIG. 2; [Figure 4B] FIG. 3 shows a perspective view of the second layer of the backplate without openings for the posts of the drive units of the configuration of FIG. 2. [Figure 4C] FIG. 4C illustrates a cross-sectional view of an assembled backplate including the first and second layers of FIGS. 4A and 4B. [Figure 5A] 3A-3D show stages of manufacturing an intermediate product for the further manufacturing of a column for a drive unit of the configuration according to FIG. 2. [Figure 5B] 3A-3D show stages of manufacturing an intermediate product for the further manufacturing of a column for a drive unit of the configuration according to FIG. 2. [Figure 5C] 3A-3D show stages of manufacturing an intermediate product for the further manufacturing of a column for a drive unit of the configuration according to FIG. 2. [Figure 5D] 3A-3D show stages of manufacturing an intermediate product for the further manufacturing of a column for a drive unit of the configuration according to FIG. 2. [Figure 6A] FIG. 5D shows a group of welds on the intermediate product according to FIG. 5C. [Figure 6B] FIG. 5D shows a group of welds on the intermediate product according to FIG. 5C. [Figure 6C] FIG. 5D shows a group of welds on the intermediate product according to FIG. 5C. [Figure 7] 5A-6C show perspective views of a pillar separated from an intermediate product as prepared according to FIGS. [Figure 8] 6B shows a planar front view of the intermediate product of FIG. 6A with two weld seams and two cross sections of the pillars that will be cut out from the intermediate product. [Figure 9] FIG. 1 shows a front view of the end face of a column with a weld. [Figure 10] 10 shows a cross-sectional view of a second embodiment of a drive unit-impeller configuration. [Figure 11A] 11A to 11C show steps for manufacturing an integrated core for the drive unit according to FIG. 10. [Figure 11B] 11A to 11C show steps for manufacturing an integrated core for the drive unit according to FIG. 10. [Figure 11C] 11A to 11C show steps for manufacturing an integrated core for the drive unit according to FIG. 10. [Figure 12A] 11A-11C show welds on a unitized core as fabricated according to FIGS. 11A-11C. [Figure 12B]11A-11C show welds on a unitized core as fabricated according to FIGS. 11A-11C. [Figure 12C] 11A-11C show welds on a unitized core as fabricated according to FIGS. 11A-11C. [Figure 13A] 1A-1C illustrate cross sections through a post according to various embodiments. [Figure 13B] 1A-1C illustrate cross sections through a post according to various embodiments. [Figure 13C] 1A-1C illustrate cross sections through a post according to various embodiments. [Figure 13D] 1A-1C illustrate cross sections through a post according to various embodiments. [Figure 13E] 1A-1C illustrate cross sections through a post according to various embodiments. [Figure 13F] 1A-1C illustrate cross sections through a post according to various embodiments. [Figure 13G] 1A-1C illustrate cross sections through a post according to various embodiments. [Figure 13H] 1A-1C illustrate cross sections through a post according to various embodiments. [Figure 13I] 1A-1C illustrate cross sections through a post according to various embodiments. [Figure 13J] 1A-1C illustrate cross sections through a post according to various embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0037] Referring to FIG. 1 , a cross-sectional view of blood pump 1 is shown. Blood pump 1 comprises pump casing 2 having blood inlet 21 and blood outlet 22. Blood pump 1 is designed as an intravascular pump, also known as a catheter pump, and is deployed within a patient's blood vessels using catheter 25. Blood inlet 21 is at the end of a flexible cannula 23, which, in use, may be placed through a heart valve, such as the aortic valve. Blood outlet 22 is located within the side of pump casing 2 and may be placed within a heart vessel, such as the aorta. Blood pump 1 is electrically connected to electrical wires 26 extending through catheter 25 for providing power to blood pump 1 to drive pump 1 using drive unit 4, as described in more detail below.

[0038] If the blood pump 1 is intended for use in a long-term application, i.e., in a situation where the blood pump 1 is implanted in a patient for several weeks or even months, power is preferably supplied using a battery. This allows the patient to be mobile, as the patient is not connected by a cable to a base point. The battery may be carried by the patient and may supply electrical energy to the blood pump 1, for example, wirelessly.

[0039] Blood is transported along a passage 24 connecting a blood inlet 21 and a blood outlet 22 (the blood flow is indicated by an arrow). An impeller 3 is provided to transport blood along the passage 24 and is rotatably mounted within the pump casing 2 around a rotation axis 10 using a first bearing 11 and a second bearing 12. The rotation axis 10 is preferably the longitudinal axis of the impeller 3. Both bearings 11 and 12 are contact-type bearings in this embodiment. However, at least one of the bearings 11 and 12 could be a non-contact bearing, such as a magnetic or hydrodynamic bearing. The first bearing 11 is a pivot bearing with a spherical bearing surface that allows rotational and, to some extent, pivotal movement. A pin 15 is provided that forms one of the bearing surfaces. The second bearing 12 is disposed within a support member 13 for stabilizing the rotation of the impeller 3, and the support member 13 has at least one opening 14 for blood flow. The impeller 3 has blades 31 mounted thereon for transporting blood as the impeller 3 rotates. Rotation of the impeller 3 is caused by a drive unit 4 that is magnetically coupled to magnets 32 at the end portions of the impeller 3. The illustrated blood pump 1 is a mixed blood pump, with the primary direction of flow being axial. It will be appreciated that the blood pump 1 could also be a purely axial blood pump, depending on the configuration of the impeller 3, and in particular the blades 31.

[0040] The blood pump 1 includes an impeller 3 and a drive unit 4. The drive unit 4 includes a plurality of pillars 40, such as six pillars 40, only two of which are visible in the cross-sectional view of FIG. 1 . The pillars 40 are arranged parallel to the rotation axis 10; more specifically, the longitudinal axis of each of the pillars 40 is parallel to the rotation axis 10. One end of the pillar 42 is disposed adjacent to the impeller. Coil windings 44 are disposed around the pillars 40. The coil windings 44 are sequentially controlled by a control to generate a rotating magnetic field. Part of the control unit is a printed circuit board 6 connected to electrical wires 26. The impeller includes a magnet 32, which in this embodiment is formed as a multi-piece magnet. The magnet 32 ​​is disposed at the end of the impeller 3 facing the drive unit 4. The magnet 32 ​​is positioned to interact with the rotating magnetic field to cause rotation of the impeller 3 about the rotation axis 10.

[0041] To close the magnetic flux path, a backplate 50 is disposed on the end of the pillar 40 opposite the impeller side of the pillar. The pillar 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, especially 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 for a reduction in the overall diameter of the blood pump 1, which is important for intravascular blood pumps. For the same purpose, a yoke 37, i.e., an additional impeller backplate, is provided within the impeller 3 on the side of the magnet 32 ​​facing away from the drive unit 4. In this embodiment, the yoke 37 has a conical shape to guide the blood flow along the impeller 3. The yoke 37 may also be made of cobalt steel. One or more washout channels extending toward the center bearing 11 may be formed within the yoke 37 or the magnet 32.

[0042] Figure 2 shows a cross-sectional view of a preferred embodiment of a drive unit-impeller arrangement for the blood pump according to Figure 1. As can be seen in Figure 2, the impeller ends 420 of the pillars 40 do not extend radially beyond the windings 44. Rather, the cross section of the pillars 40 is constant in the direction of the longitudinal axis LA of the pillars 40. Thus, the pillars 40 are avoided from coming close to each other, as this would cause a partial magnetic short circuit and, consequently, a reduction in the power of the electric motor of the blood pump.

[0043] 2 may include at least two, at least three, at least four, at least five, or preferably six pillars 40. A greater number of pillars 40, such as nine or twelve, may also be possible. Due to the cross-sectional view, only two pillars 40 are visible. The pillars 40 and backplate 50 form the magnetic core 400 of the drive unit 4, which may have a diameter of less than 10 mm.

[0044] The pillar 40 may be comprised of a discontinuous soft magnetic material that is discontinuous in electrical conductivity, as shown. The discontinuous soft magnetic material includes a plurality of sheets 85 made of a ferromagnetic material that are stacked together. The stacking direction is aligned along the longitudinal axis LA of the pillar 40 and is labeled by the arrow DL. As shown, the pillar 40 is aligned parallel to the axis of rotation 10.

[0045] A spacer 7 is disposed around the pillars 40. It is made of a magnetically inert material and has the purpose of maintaining a constant distance between the pillars 40 at their impeller-side ends 420. The spacer 7 will be described in more detail with respect to FIGS. 3A-3C. The impeller-side ends 424 of the coil windings 44 extend up to the spacer 7. A backplate 50 is provided at the other end of the pillars 40. According to the embodiment shown in FIG. 2, the backplate 50 has a recess for receiving the pillars 40 therein. More specifically, it includes a first layer 51 having an opening 511 for the rear end 450 of the pillar 40. The backplate 50 will be described in more detail with respect to FIGS. 4A-4C.

[0046] It is conceivable to realize embodiments of the blood pump 1 having any combination of the three above-mentioned features: the impeller-side ends 424 of the pillars not extending radially beyond the impeller-side ends 450 of the windings 44; providing magnetically inactive spacers 7 between the pillars 40; and a backplate 50 having recesses for receiving the rear ends 450 of the pillars 40.

[0047] 3A-3C show perspective, front, and side views of the spacer 7, respectively. The spacer 7 generally has the form of a disk or wheel with a central through-hole 75. The spacer 7 includes an opening 71 for each of the posts. For an embodiment with six posts 40, six openings 71 are present, as shown. Spaced spokes 72 are positioned between the openings 71. When the posts 40 are inserted into the openings 71, the spaced spokes 72 maintain a constant distance between the posts 40. The spacer 7 further includes outer and inner rims 73 and 74 that connect adjacent spaced spokes 72 and stabilize the spacer. The spacer 7 is made of titanium, a paramagnetic material that avoids magnetic short circuits when placed between the impeller-side ends 420 of the posts 40. Titanium provides high mechanical strength, which allows for the fabrication of a spacer 7 with a small thickness, which is advantageous in terms of construction space consumption.

[0048] FIG. 4A shows a perspective view of the first layer 51 of the backplate 50. The first layer 51 has the general shape of a disk or wheel with a central hole 515. The first layer 52 includes openings 511 in which the rear ends 450 of the posts 40 are positioned. The first layer 51 includes spaced-apart spokes 512 disposed between the openings 511. One purpose of the spaced-apart spokes 512 is to maintain a constant distance between the rear ends 450 of the posts 40. The first layer 51 further includes outer and inner rims 513 and 514 that connect the spaced-apart spokes 512 at the outer and inner radial ends of the openings 511, respectively. The first layer 51 may be made of a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity. It may be composed of several ferromagnetic sheets 85, particularly three sheets as shown in FIG. 4A. The sheets 85 are laminated together using an electrically non-conductive material to form the discontinuous soft magnetic material. The stacking direction DL is generally parallel to the sheets 85, and the direction of the main extent of the sheets defines the stacking plane. Within the backplate 50, the sheets 85 are perpendicular to the axis of rotation 10. In the center of the first layer 51, a hole 515 is arranged, the purpose of which may be to facilitate assembly of the first layer 51 and the second layer 52, e.g., to center the first and second layers 51, 52.

[0049] FIG. 4B shows a perspective view of the second layer 52 of the backplate 50. The second layer 52 has substantially the form of a disk with a central hole 525 corresponding to the hole 515 in the first layer 51. The second layer 52 does not have any openings for the rear ends of the posts 40. Instead, the second layer 52 has a contact plane 526 facing the rear ends 450 of the posts 40. In the assembled state of the drive unit, the rear ends 450 of the posts are in contact with the contact plane 526 of the second layer 52 of the backplate 50, transmitting magnetic flux between the rear ends 450 of the posts 40 and the backplate 50. Because all rear ends 450 of the posts 40 are in contact with the contact plane 526, magnetic flux can be exchanged between the posts 40, and a magnetic null point can be created in the second layer 52. To make this possible, 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 stacked sheets 85 similar to the structure described above for the first layer 51. As an example, three sheets 85 may constitute the second layer 52, as shown in FIG. 4B . Within the second layer 52, the stacking direction D is perpendicular to the rotation axis 10. The sheets 85 are ferromagnetic and electrically conductive, whereas the intermediate layers between the sheets 85, not explicitly shown, are non-ferromagnetic and electrically non-conductive. This type of discontinuous soft magnetic material reduces eddy currents that would otherwise be generated in greater amounts by changes in magnetic flux. The hole 525 in the center of the second layer 52 may facilitate assembly of the first layer 51 and the second layer 52, e.g., centering the first and second layers 51, 52.

[0050] FIG. 4C shows a cross section of the backplate 50. It is composed of a first layer 51 and a second layer 52 bonded together at their major surfaces with the largest extent. The bond between the first layer 51 and the second layer 52 of the backplate 50 can be established in the same manner as between the sheets 85 of the first and second layers 51, 52. The through-holes 515 and 525 of the first layer 51 and the second layer 52 are aligned with each other 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, thereby forming a recess 501 for receiving the rear end 450 of the post 40. A contact plane 526 is formed at the base of the recess 501. When the post 40 is inserted into the recess 501, the rear end 450 contacts the contact plane 526. Furthermore, the positions of the pillars 40 are fixed by the spaced spokes 512 and by the outer and inner rims 513, 514, which together surround each pillar 40. Thus, a magnetic connection is established between the second layer 52 and the rear end surface 45 of the pillar 40 at the contact plane 526, and a second magnetic connection is also established between the pillar 40 and the aforementioned surrounding portion of the first layer 51. However, the main part of the magnetic flux is transmitted through the contact plane 526. Preferably, the surface at the rear end 450 of the pillar 40 has a predetermined flatness, and the contact plane 526 also has a predetermined flatness. In this way, the gap between the surface 45 at the rear end 450 of the pillar 40 and the contact plane 526 can be maintained below a specific size, preferably less than 10 μm. This improves the transmission of magnetic flux between the pillar 40 and the backplate 50. Preferably, no additional material is present between the surface 45 at the rear end 450 of the pillar 40 and the contact plane 526. In this embodiment of the invention, the transmission of magnetic flux through surface 45 and backplate 50 is independent of the manner in which posts 40 are fastened to backplate 50 .

[0051] Figures 5A to 5D show the preparatory steps for the production of the pillars 40. Figure 5A shows a perspective view of a plate 8 of discontinuous soft magnetic material, which is discontinuous in terms of electrical conductivity, hereinafter also referred to as workpiece.

[0052] In Figure 5A, plate 8 is marked with a width W for cutting workpiece bar 81 from plate 8. The width W of workpiece bar 81 is identical to the length of column 40 that will be produced from workpiece bar 81. Figure 5B shows an enlarged view of the area marked by rectangle R in Figure 5A. Here, stacked sheets 85 of discontinuous soft magnetic material are visible. The direction of lamination DL runs along the main plane of plate 8, thus forming the lamination plane.

[0053] Figure 5C shows workpiece bar 81 cut as a discrete piece of material from plate 8. Figure 5D shows an enlarged view of the portion labeled by rectangle R in Figure 5C. Sheet 85 of workpiece bar 81 is visible in this enlargement.

[0054] 6A shows the workpiece bar 81 of FIGS. 5C and 5D, which forms the basis for the welding step in preparation for cutting out the pillars 40 from the bar 81. On the side of the bar 81 facing left in FIG. 6A, a number of cross sections 84 of the pillars 40 to be produced from the bar 81 are shown. The pillars 40 are produced by cutting out these cross sections 84 from the bar 81. Since the width W of the bar 81 corresponds to the length of the pillar 40, the side surfaces 811 and 812 of the bar 81 become the end faces of the impeller end 420 and the rear end 450 of the pillar 40.

[0055] FIG. 6B shows the next preparatory step before cutting out the pillars 40. Two weld seams 82 and 83 are welded on the face 811 of the bar 81, spaced apart from each other and across each cross section 84 of the pillars 40 to be cut out. The weld seams 82 and 83 extend perpendicular to the lamination direction DL of the sheets 85. In this way, the discontinuous sheets of material are connected to each other. Instead of two weld seams, a single weld seam can be provided. In addition, a similar weld seam can be provided on the opposite side 812 of the bar 81. The sheets 85 have a better mechanical connection to each other thanks to the weld seams 82 and 83, and are also electrically connected. This has the advantage that current can flow from any location on the discontinuous soft-magnetic material destined for the pillars 40 to each location of the electrical connection on the bar 81 that may be required, for example, for electrical discharge machining. In this way, electrical discharge machining is significantly facilitated. Furthermore, since the cut-out pillars 40 cannot be decomposed due to delamination, higher process reliability is achieved. Preferably, laser welding is applied. It may be advantageous to apply the welding power twice or even multiple times to the same weld. In Figure 6C, a portion of the bar 81 marked by the rectangle R is shown enlarged.

[0056] Thus, FIG. 6C shows a number of cross sections 84 of the posts 40 to be cut from the bar stock 81. The cross sections 84 have a substantially triangular shape. As shown, the corners may be rounded. The convex side 842 of the triangle shown on the left side of the cross section 84 in FIG. 6C has a convex shape. 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 corner 841 of the cross section 84 opposite the convex side 842 of the cross section 84 is aligned with the stacking direction DL. In this way, the sheet 85 extends symmetrically through the cross section 84.

[0057] 7 shows a post 40 cut from a bar 81. As can be seen on surface 45 at the rear end 450 of the bar 81, weld seams 82 and 83 are still present on this surface. The post 40 has a constant cross section 84 along its entire length. The weld seams 82 and 83 are deburred after the post 40 is cut.

[0058] FIG. 8 shows another configuration of two cross sections 84 on a side surface 811 of a workpiece bar 81. In contrast to the workpiece bar 81 shown in FIGS. 6A-6C, the side surface 811 of the workpiece bar 81 in FIG. 8 has a size that allows two cross sections 84 to be arranged next to each other in a direction perpendicular to the stacking direction DL. The cross sections 84 are oriented with respect to the stacking direction DL so that the bisector B of each cross section 84 opposite its respective convex side 842 is aligned with the stacking direction DL. Arranging the cross sections 84 along the bar 81 in this manner saves material. Less waste material is generated. Depending on the thickness of the bar 81 and the required cross-sectional dimensions of the column 40, it is conceivable to stack even more cross sections 84 of the column 40 in a direction perpendicular to the stacking direction DL. Weld seams 82 and 83 each extend across each of the cross sections 84. The weld seams 82, 83 also extend perpendicular to the stacking direction DL across the entire side surface 811 of the bar 81. In this way, all the discontinuous sheets 85 of soft magnetic material of the bar 81 are connected to one another.

[0059] Figure 9 shows an example of a column 40 cut from welded bar stock 81, i.e., a front view on one of the end faces of the column 40. As shown in Figure 9, a single weld seam 86 of considerable width, which may cover more than about one-third of the height of the triangular cross section 84, extends along the convex side 842 of the cross section 84. The weld seam 86 runs perpendicular to the stacking direction DL and connects all of its sheets. Again, the bisector B of the corner 841 opposite the convex side 842 is aligned with the stacking direction DL.

[0060] Figure 10 shows a second embodiment of a drive unit-impeller arrangement for the blood pump 1 according to Figure 1. As with the first embodiment shown in Figure 2, the impeller ends 420 of the pillars 40 do not extend radially beyond the windings 44. Rather, the cross section of the pillars 40 is constant in the direction of their longitudinal axis LA. Thus, the pillars 40 are prevented from coming too close to each other, as this would cause a partial magnetic short circuit and, consequently, a reduction in the power of the electric motor of the blood pump.

[0061] 10 may include at least two, at least three, at least four, at least five, or preferably six pillars 40. A greater number of pillars 40 may be possible, such as eight, ten, or twelve. Due to the cross-sectional view, only two pillars 40 are visible. The pillars 40 and backplate 50 form the magnetic core 400 of the drive unit 4, which may have a diameter of less than 10 mm.

[0062] This embodiment differs from the first embodiment shown in FIG. 2 by a different structure of the magnetic core. Here, the magnetic core 400 includes the magnetic components of the drive unit 4, namely the post 40 and the backplate 50, in one single part or monoblock. The monoblock consists of a discontinuous soft magnetic material. The discontinuous soft magnetic material is discontinuous in terms of electrical conductivity. As shown, it includes multiple sheets 85 of ferromagnetic material stacked on top of each other to form the monoblock 9 as shown in FIG. 11C. The stacking direction DL is parallel to the rotation axis 10.

[0063] The coil winding 44 extends to the impeller-side end 420 of the pillar 40. This has the advantage that magnetomotive force can be generated along the entire pillar 40. The magnetic core 400 includes a protrusion 401 at the rear end 450 of the pillar 40 that protrudes radially relative to the pillar 40. This protrusion 401 can serve as a stopper for the coil winding 44 toward the backplate 50. Because the integrated magnetic core 400 has high rigidity between the backplate 50 and the pillar 40, spacers between the pillars 40 at the impeller-side end 420 of the pillars can be omitted. The integrated magnetic core 400 has the advantage that an optimal magnetic connection between the pillar 40 and the backplate 50 can be achieved. The magnetic core 400 can have a diameter of less than 10 mm.

[0064] 11A-11C illustrate steps for fabricating a magnetic core 400 for a drive unit 4 of the drive unit-impeller configuration as shown in FIG. 10. FIG. 11A illustrates in perspective view a cube-shaped monoblock 9 forming the workpiece for fabricating the magnetic core 400. The monoblock 9 is made of discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity. It includes sheets 85 oriented in a stacking direction DL extending along the major planes of the sheets 85. The sheets 85 are each joined to their respective adjacent sheets by a joining layer of electrically non-conductive material, not explicitly shown in FIGS. 11A-11C.

[0065] 11B shows the magnetic core 400 in a semi-finished state in which it has been processed, e.g., transformed, from a cubic monoblock 9 into a substantially cylindrical body 94. During this processing step, protrusions 401 are produced. Reduced diameter sections 404 of body 94, which form the peripheral surfaces of the pillars 40 of the magnetic core 400, are produced to have a diameter corresponding to the outer radius of the outermost convex side surfaces 842 of the pillars 40.

[0066] Next, the body 94 can be further fabricated to produce the magnetic core 400 as shown in FIG. 11C. For this production step, electrical discharge machining can be used. In particular, wire-cut electrical discharge machining can be applied to produce the slots 49 that separate the posts 40 from one another. Inside the slots, space is provided for the coil windings 44. At the base of the slots 49, an intermediate section 59 of the integral backplate 50 extends between the rear ends of the posts 40. The intermediate section is integral with the posts 40 and the backplate 50. The entire magnetic core is therefore formed by a monoblock 9.

[0067] The lamination direction DL in the magnetic core 400 is such that it is parallel to the axis of rotation 10. It is permissible that the lamination direction DL in the base plate 50 is not parallel to the magnetic flow between the posts 40 in the base plate 50. It is also possible to fabricate the magnetic core 400 from coiled soft magnetic sheet material separated by electrically non-conductive layers. In this case, the lamination direction DL in the base plate 50 is always circumferential, which is advantageous for avoiding eddy currents in the magnetic flux in the base plate 50.

[0068] 12A-12C show how one or more welds can be provided on the surface of the integrated magnetic core as produced according to FIGS. 11A-11C. Thus, in the illustrated embodiment, three weld seams 82, 83 are provided on one side of the cubic monoblock 9. The weld seams 82, 83 are welded at a distance from each other and across the cross section of the body 94 to be cut out of the monoblock 9. The weld seams 82, 83 extend perpendicular to the lamination direction DL of the sheets 85. In this way, discontinuous sheets of soft magnetic material are connected to each other. Instead of three weld seams, more weld seams or a single wide weld may be provided. Additionally, a similar weld seam may be provided on the opposite side of the monoblock 9 (not shown). As an alternative to, or in addition to, the welds on the opposite side, one or more weld seams may be provided on the side of the monoblock 9 at the level of the backplate 50, completely or at least partially surrounding the backplate 50. The sheets 85 have a better mechanical connection to each other due to the weld seams 82, 83 and are also electrically connected. The latter has the advantage that current can flow from any position in the discontinuous soft-magnetic material to each position of the electrical connection in the body 94 that may be required, for example, for electrical discharge machining. In this way, electrical discharge machining is greatly facilitated. Furthermore, a higher process reliability is achieved, since the backplate-pillar unit cut out from the body 94 cannot disintegrate due to delamination. Preferably, laser welding is applied. It may be advantageous to apply the welding power twice or even multiple times to the same weld.

[0069] Figures 13A-13J show various embodiments of a pillar in cross section. Figures 13A-13D show an embodiment in which the pillar is grooved, i.e., formed of multiple sheets 171 insulated from one another by insulating layers 172. The insulating layers 172 can include adhesive, lacquer, baked enamel, or the like. Figures 13A and 13B show an embodiment in which the sheets 171 are uniform in thickness. The thickness can range from 25 μm to 450 μm. The sheets 171 shown in Figure 13A have a greater thickness than the sheets 171 shown in Figure 13B. The sheets in Figure 13C have varying thicknesses, with the center sheets having the greatest thickness and the outermost sheets having the least thickness. This can be advantageous because eddy currents in the side regions of the pillar are more significant and can be reduced by thinner sheets. Eddy currents in the center region are less significant, and a relatively thick center sheet can help improve magnetic flux. The orientation of the sheets 171 may vary, as exemplarily shown in FIG. 13D, so long as the soft magnetic material shown in cross section, i.e., the soft magnetic material in a cross section across the direction of magnetic flux, is discontinuous or interrupted.

[0070] 13E and 13F show embodiments in which the posts 141 are formed by a bundle of wires 181 insulated from one another by insulating material 182. The insulating material 182 can be present as a coating on each of the wires 181 or can be a matrix in which the wires 181 are embedded. In the embodiment of FIG. 13E, all of the wires have the same diameter, whereas in the embodiment of FIG. 13F, the center wire has the largest diameter and the outer wires have smaller diameters, similar to the embodiment shown in FIG. 13C having sheets with varying thicknesses. As shown in FIG. 13G, wires 181 of different diameters may be mixed, which can increase the total cross-sectional area of ​​the soft magnetic material compared to embodiments in which all wires have the same diameter. Alternatively, the wires 183 can have polygonal cross-sectional areas, such as rectangular, square, etc., to further minimize the insulating layers 184 between the wires 183.

[0071] Alternatively, the discontinuous cross-section of the pillar 141 may be created by metal particles 185 embedded in a polymer matrix 186, as shown in FIG. 13I, or by steel wool or other porous structure impregnated with an insulating matrix. Porous, and therefore discontinuous, structures of soft magnetic material may also be produced by sintering or high-pressure molding processes, in which case the insulating matrix may be omitted because the insulating layer is automatically formed by oxidation of the soft magnetic material upon exposure to air. Furthermore, the pillar 141 may be formed from rolled sheets 187 of soft magnetic material, with layers of the rolled sheets 187 separated by insulating layers 188, as shown in FIG. 13J. This also results in a discontinuous cross-section in the sense of the present invention, which reduces eddy currents in the pillar 141 or pillar 40.

Claims

1. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump casing (2) having a blood inlet (21) and a blood outlet (22); an impeller (3) rotatably disposed within the pump casing (2) about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey blood from the blood inlet (21) to the blood outlet (22); a drive unit (4) for rotating the impeller (3), the drive unit (4) including a plurality of pillars (40) arranged around the rotation axis (10) and a back plate (50) connecting rear ends (450) of the pillars (40), the pillars (40) and the back plate (50) forming a magnetic core (400) of the drive unit (4); a coil winding (44) disposed around each of the pillars (40), the coil winding (44) being controllable to create a rotating magnetic field; Equipped with An intravascular blood pump (1) in which the impeller (3) includes a magnetic structure (32) arranged to interact with the rotating magnetic field to cause rotation of the impeller (3), The magnetic core (400) or a portion thereof comprises or consists of a discontinuous soft magnetic material that is discontinuous in electrical conductivity in a cross section, and at least one weld (82, 83, 86) is provided on a surface (811) of the discontinuous soft magnetic material, and the weld (82, 83, 86) bridges at least one discontinuity in electrical conductivity in the discontinuous soft magnetic material.

2. 2. The intravascular blood pump (1) according to claim 1, wherein at least one of the at least one welded portion (82, 83, 86) is arranged on a rear end surface (45) of the column.

3. 2. The intravascular blood pump (1) according to claim 1, wherein at least one of the at least one welded portion (82, 83, 86) is disposed on the impeller-side end surface of the column (40).

4. 2. The intravascular blood pump (1) according to claim 1, wherein at least one of the at least one welded portion (82, 83, 86) is arranged on the impeller-side end face (45) of the column (40), and at least one further welded portion (82, 83, 86) is arranged on the rear end face (45) of the column (40).

5. 5. An intravascular blood pump (1) according to any one of claims 1 to 4, characterized in that two of the at least one welded portion (82, 83, 86) are arranged spaced apart from each other at one end of the column (40).

6. 6. An intravascular blood pump (1) according to any one of claims 1 to 5, characterized in that at least one of the at least one weld (82, 83, 86) extends over a side of the pillar (40), preferably at least partially surrounding at least one of the pillars (40).

7. 7. An intravascular blood pump (1) according to any one of claims 1 to 6, characterized in that more than one of the at least one weld (82, 83, 86) is arranged on the same surface side of the pillar (40).

8. 8. An intravascular blood pump according to any one of claims 1 to 7, wherein the at least one weld (82, 83, 86) comprises a weld seam bridging the at least one discontinuity in electrical conductivity within the discontinuous soft magnetic material.

9. 9. An intravascular blood pump (1) according to any one of claims 1 to 8, characterized in that at least one of the pillars (40) comprises a laminate of soft magnetic material having soft magnetic sheets (85) oriented parallel to its longitudinal axis (LA).

10. 10. An intravascular blood pump (1) according to claim 9, characterized in that the at least one of the pillars (40) has a triangular cross section (84) transverse to the axis of rotation (10), and the soft magnetic sheet (85) of soft magnetic material is oriented in or parallel to a plane passing through the bisector (B) of the triangular cross section (84).

11. A method for manufacturing a magnetic core (400) or a part of a magnetic core (400) for an intravascular blood pump (1), in particular for a drive unit (4) for an intravascular blood pump (1) according to any one of claims 1 to 10, comprising the following steps: providing a workpiece (8, 81) of discontinuous soft magnetic material, said soft magnetic material being discontinuous in terms of electrical conductivity within the cross section of said workpiece (8, 81), from which said magnetic core (400) or said part of said magnetic core (400) is to be produced; - providing welds (82, 83, 86) on the surface (811) of the workpiece (8, 81), whereby the welds (82, 83, 86) bridge at least one discontinuity in electrical conductivity in the discontinuous soft magnetic material of the workpiece (8, 81); A method characterized by:

12. 12. The method of claim 11, wherein after providing the weld, the magnetic core (400), or the portion of the magnetic core (400), is separated from the workpiece (8, 81).

13. 13. The method of claim 12, wherein after separating the magnetic core (400), or the portion of the magnetic core (400), from the workpiece (8, 81), at least a portion of the weld (82, 83, 86) remains on the magnetic core (400), or the portion of the magnetic core (400).

14. 14. The method according to claim 12 or 13, characterized in that the step of separating the magnetic core (400), or the part of the magnetic core (400), from the workpiece (8, 81) comprises separating at least one of the pillars (40) from the workpiece (8, 81) by electrical discharge machining.

15. 15. The method according to any one of claims 12 to 14, characterized in that the at least one weld (82, 83, 86) is produced by laser welding or by a double application of a welding laser, in particular by double laser welding.

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