Blood pump

Abstract

The invention relates to a blood pump and a method of manufacturing a magnetic core. A blood pump includes a pump housing having a blood flow inlet and a blood flow outlet, an impeller disposed in the pump housing to be rotatable about an axis of rotation. The impeller has blades sized and shaped for delivering blood from the blood flow inlet to the blood flow outlet. The blood pump comprises a drive unit for rotating the impeller, comprising a plurality of cylinders arranged about an axis of rotation and a back plate connecting the rear end of the parts, the cylinders and back plate together forming a magnetic core of the drive unit. A coil winding is disposed around each of the cylinders. The coil windings can be controlled to create a rotating magnetic field, and the impeller comprises a magnetic structure arranged to interact with the rotating magnetic field to cause the impeller to rotate. The magnetic core or a part thereof includes a discontinuous soft magnetic material which is discontinuous in electrical conductivity in a cross section, and at least one solder portion is provided on a surface of the discontinuous soft magnetic material. The welding portion engages at least one discontinuity in the discontinuous soft magnetic material in terms of conductivity.

Description

[0001] Divisional application

[0002] This application is a divisional application of the patent application with application number 202080022900X, international application date March 16, 2020, entry into the Chinese national phase date September 18, 2021, and invention name “Blood Pump”. Technical Field

[0003] The present invention relates to a 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 drive unit. Background Art

[0004] Different types of blood pumps are known, such as axial 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. The blood pump generally comprises a pump housing having a blood flow inlet and a blood flow outlet connected by a passage. In order to induce blood flow along the passage from the blood flow inlet to the blood flow outlet, an impeller or rotor is rotatably supported in the pump housing, wherein the impeller is provided with blades for conveying blood.

[0005] The blood pump is generally driven by a drive unit, which may be an electric motor. For example, US 2011 / 0238172 A1 discloses an extracorporeal blood pump having an impeller, which may be magnetically coupled to an electric motor. The impeller includes a magnet, which is arranged adjacent to a magnet in the electric motor. Due to the attraction between the magnets in the impeller and the motor, the rotation of the motor is transmitted to the impeller. In order to reduce the number of rotating parts, it is also known from US 2011 / 0238172 A1 to utilize a rotating magnetic field, wherein the drive unit has a plurality of stator cylinders arranged around a rotation axis, each cylinder carrying a coil winding and acting as a magnetic core. The control unit sequentially supplies voltage to the coil winding to create a rotating magnetic field. In order to provide a sufficiently strong magnetic coupling, the magnetic force must be high enough, which can be achieved by supplying a sufficiently high current to the drive unit or by providing a large magnet, which, however, results in a larger overall diameter of the blood pump.

[0006] EP 3222301 B1 discloses a blood pump, in particular an intravascular blood pump, with magnetic coupling between a drive unit and an impeller, wherein the blood pump has a compact design, in particular a high ratio of pumping power to the size of the pump, resulting in outer dimensions that are small enough to allow the blood pump to be inserted transvascularly, transvenously, transarterially, or transvalvularly, or even smaller for reasons of operational convenience.

[0007] More specifically, the blood pump in EP 3222301 B1 includes a pump housing with a blood flow inlet and a blood flow outlet, an impeller, and a drive unit for rotating the impeller. Through the rotation of the impeller around the rotation axis inside the pump housing, blood can be transported from the blood flow inlet to the blood flow outlet through the blades of the impeller. The drive unit includes a plurality of, preferably six, cylinders and a back plate connecting the rear ends of the cylinders to act as a yoke. The cylinders and the back plate constitute the magnetic core of the drive unit. When viewed in a plane perpendicular to the rotation axis, the cylinders are arranged in a circular shape around the rotation axis, wherein each cylinder has a longitudinal axis, which is preferably parallel to the rotation axis. The cylinders have a coil winding arranged around each cylinder. In order to generate a rotating magnetic field to drive the impeller, the coil winding can be controlled in a coordinated manner. The impeller includes a magnetic structure in the form of a magnet, which is arranged to interact with the rotating magnetic field so that the impeller rotates with it.

[0008] According to the unpublished European patent application No. 17191940.0, in order to keep the eddy current losses low, discontinuous soft magnetic materials can be used for the magnetostrictive components of the drive unit, in particular for the cylinder. The discontinuous material can be, for example, a laminated material comprising soft magnetic sheets. However, magnetostrictive components of the drive unit made of such material are prone to disintegration and fall apart at the delaminations between the sheets. Another problem is the possibility of manufacturing such components by electrical discharge machining. When such a workpiece is contacted for electrical discharge machining at a certain point, not all other points of the material are in electrical contact with the contacted point. This can complicate the electrical discharge machining.

[0009] It is an object of the invention to facilitate the manufacture of a drive unit for an intravascular blood pump. Summary of the invention

[0010] The blood pump of the invention corresponds to the blood pump described above in EP 3222301 B1. Accordingly, it can be an axial blood pump or a diagonal blood pump that pumps partly axially and partly radially (the diameter of a pure centrifugal blood pump is usually too large for intravascular applications). However, according to one aspect of the invention, the magnetic core or a part thereof, in particular at least one of the cylinders, comprises or consists of a discontinuous soft magnetic material, which is discontinuous in terms of electrical conductivity in a cross section transverse to the longitudinal axis of the respective cylinder. At least one weld is provided on the surface of the discontinuous soft magnetic material, in particular on at least one of the cylinders. The weld bridges the discontinuity in terms of electrical conductivity in the discontinuous soft magnetic material.

[0011] Each of the cylinders has a longitudinal axis. Preferably, the longitudinal axis of each cylinder is parallel to the axis of rotation. The cylinders each include a soft magnetic material that is discontinuous in a cross section that is transverse to, preferably perpendicular to, the longitudinal axis of the corresponding cylinder. In other words, the soft magnetic material of the cylinder is discontinuous in a cross section that is transverse to, preferably perpendicular to, the direction of the magnetic flux caused by the corresponding coil winding in the cylinder. By separating or interrupting the soft magnetic material in the cross section, eddy currents in the cylinder can be reduced or avoided, so that heat generation and energy consumption can be reduced. Reducing energy consumption is particularly useful for long-term applications of blood pumps, in which it is desired that the blood pump is battery-powered and provides mobility for the patient. Moreover, in long-term applications, the blood pump can be operated without purging, which is only possible when the heat generation is low.

[0012] "Discontinuous" in the sense of this application document means that the soft magnetic material seen in any cross-section transverse to the longitudinal axis is interrupted, separated, truncated, etc. by insulating material or other materials or gaps to form strictly separated areas of soft magnetic material or areas that are interrupted but connected at different locations.

[0013] Discontinuous soft magnetic materials provided in a cross-sectional plane transverse to the direction of the magnetic flux reduce eddy currents and thus reduce heat generation and energy consumption, as described above. In order to substantially not weaken the magnetic field compared to continuous or full-body (i.e. solid) soft magnetic materials, the total amount of soft magnetic materials is maximized while minimizing the continuous area of ​​the soft magnetic materials. This can be achieved, for example, by providing a soft magnetic material in the form of a plurality of soft magnetic material sheets, 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 arranging adhesives, lacquers, porcelain, etc. between adjacent sheets in the sheets. This arrangement can be called "slotted". Compared to full-body soft magnetic materials, the amount of soft magnetic material is only reduced a little and the amount of insulating material remains small, so that the magnetic field caused by the slotted cylinder is substantially the same as the magnetic field caused by the solid cylinder. In other words, while heat generation and energy consumption can be significantly reduced, the loss of the magnetic field caused by the insulating material is negligible.

[0014] The sheet preferably extends substantially parallel to the longitudinal axis of the respective cylinder. In other words, the sheet may extend substantially parallel to the magnetic flux direction, so that the cylinder is discontinuous in a cross section transverse to or perpendicular to the magnetic flux direction. It will be appreciated that the sheet may extend at an angle relative to the longitudinal axis of the respective cylinder, as long as the soft magnetic material is discontinuous in a cross section transverse to the longitudinal axis. The sheet preferably has a thickness in the range of 25 μm to 1 mm, more preferably 50 μm to 450 μm, for example 200 μm.

[0015] It is well known to provide slotted soft magnetic material, such as electrical steel, in electric motors to avoid or reduce eddy currents. However, this technology has been applied in the past to large devices where the sheet material typically has a thickness 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 cylinders typically has a diameter of the order of magnitude and the power input is relatively low (e.g., up to 20 watts (W)), eddy currents and related problems are not expected. Unexpectedly, although the diameter of the cylinder is small, eddy currents and therefore heat generation and energy consumption can be reduced by providing a slotted cylinder. This is beneficial to the operation of the blood pump, which can operate at high speeds of up to 50,000 rpm (revolutions per minute).

[0016] It will be appreciated that other arrangements other than the above-described slotted arrangements may be used to provide discontinuous soft magnetic material in the column. For example, instead of a plurality of sheets, a plurality of wires, fibers, columns or other elongated elements may be provided to form each column of the drive unit. Wires and the like may be provided in the form of bundles, wherein the wires are electrically insulated from one another, for example by virtue of 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, rounded, rectangular, square, polygonal, and the like. Similarly, particles of soft magnetic material, wire fleece or other sponge-like or porous structures of soft magnetic material may be provided, wherein the spaces between regions of the soft magnetic material include electrically insulating material, such as an adhesive, paint, a polymer matrix, and the like. The porous and therefore discontinuous structure of the soft magnetic material may also be formed by a sintered or pressed material. In such a structure, additional insulating material may be omitted, since the insulating layer may be automatically formed by an oxide layer caused by oxidation of the soft magnetic material when it is exposed to air.

[0017] Although other structures of sheet or soft magnetic material can be formed uniformly, i.e., the sheet in one or all cylinders in the cylinder can have the same thickness or the wire can have the same diameter, non-uniform arrangement can also be provided. For example, the sheet can have different thicknesses or the wire can have different diameters. More specifically, especially for the stacking of sheet, one or more center sheets can have a larger thickness, and the adjacent sheet towards the end of the stack can have a smaller thickness, i.e., the thickness of the sheet is reduced from the center towards the end of the stack, i.e., reduced towards the outermost sheet in the stack. Similarly, one or more center wires in the wire bundle can have a larger diameter, and the wire at the edge of the cylinder can have a smaller diameter, i.e., the diameter of the wire can be reduced from the center towards the edge of the bundle, i.e., reduced towards the outermost wire in the bundle. Providing a larger continuous area of ​​soft magnetic material in the center of the column about a cross section transverse to its longitudinal axis, i.e. providing a relatively thick sheet or wire in the center, may be advantageous because this may enhance the magnetic flux through the center along the longitudinal axis of each column, and the eddy currents in the center are less relevant than the eddy currents in the sides of the column. In other words, this arrangement may be advantageous because the eddy currents in the side regions of the column are more critical and may be reduced by thin sheets or wires in the side regions.

[0018] The weld enables easy manufacture of a core or part thereof made of a discontinuous soft magnetic material. That is, when the core or the column of the core is separated from a larger workpiece made of a discontinuous soft magnetic material, the discontinuous soft magnetic material may delaminate or lose its integrity due to the machining forces applied to the workpiece during the separation process. This is particularly critical due to the extremely small size of the core, especially its column, and may even occur when electrical discharge machining, especially electrical discharge machining by wire cutting, is used to separate the core or its column from the workpiece. By virtue of the weld applied to the workpiece before the separation step, the mechanical stability of the discontinuous material is improved. In the case where electrical discharge machining is used to cut the core or column out of the workpiece, the flow of current to the cutting site is also improved. The weld or welds may later form part of the core or column.

[0019] In particular, the end surface of the cylinder on the impeller side, oriented transversely to the axis of rotation, exposes discontinuous material. Accordingly, a weld or several welds can be arranged on the surface of the cylinder on the impeller side. Alternatively or additionally, the weld or several welds can be arranged on the rear end surface of the cylinder or, if the core including the back plate acting as a yoke is integrated into a monoblock with the workpiece, a further weld or further welds can be arranged on the rear end surface of the back plate.

[0020] Preferably, the rear end surface of at least one of the cylinders, preferably all of the cylinders, is arranged substantially perpendicular to the longitudinal axis of at least one of the cylinders. At least one of the cylinders, preferably all of the cylinders, may further comprise a circumferential / peripheral surface arranged around the longitudinal axis of the cylinder and extending along said longitudinal axis, wherein the rear end surface is arranged at a longitudinal rear end of said circumferential surface and the rear end surface faces away from the impeller. Preferably, the rear end surface is substantially perpendicular to the circumferential surface.

[0021] Preferably, the entire surface of the core or its column can be covered by the weld to join all soft magnetic components, such as sheets of discontinuous material present on the surface. Most preferably, all components of discontinuous material are joined. By joining as many soft magnetic components of discontinuous material as possible, optimal manufacturing can be achieved.

[0022] Preferably, two welds are arranged at one end of at least one cylinder at a distance from one another. These welds are preferably weld seams. Such weld seams are preferably arranged parallel to one another. In particular, the spaced seams can be welded to the surface of an unprocessed material or workpiece from which the cylinder should be cut after welding.

[0023] Alternatively or additionally, the weld or welds may extend on the side surface of the cylinder. This alternative may induce fewer eddy currents, since the weld plane is not transverse to the magnetic flux compared to the end surface of the welded cylinder.

[0024] More than one of the at least one weld may be arranged on the same surface side of at least one of the pillars, which may be a side surface or an end surface or both. In a further alternative, the weld may at least partially surround the side surface of the pillar.

[0025] Preferably, the weld or several welds are arranged as a weld seam.The seam may have a smaller cross section than a weld covering the entire surface, so that the seam may induce fewer additional eddy currents.

[0026] Like the column, the backplate may include a discontinuous soft magnetic material. Because the magnetic flux in the backplate is substantially transverse 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. This may be an exception: the column and the backplate are manufactured as a whole. In addition, substantially all functions and explanations mentioned above regarding the discontinuous material of the column are also valid for the backplate. For example, like the column, the backplate may be slit, i.e., it may be formed by a plurality of stacked sheets, and the sheets of the backplate are preferably electrically insulated from each other. The sheets of the backplate may extend substantially perpendicular to the sheets of the column. As described above, eddy currents and thereby heat generation and energy consumption may be reduced. However, the backplate may alternatively be formed by a continuous, i.e., solid, soft magnetic material.

[0027] The back plate, like the cylinder, is preferably made of a soft magnetic material, such as electrical steel (magnetic steel) or other material suitable for closing the magnetic flux circuit, preferably cobalt steel. The diameter of the back plate may be in the range of 3 mm to 9 mm, such as 5 mm or 6 mm to 7 mm. The thickness of the back plate may be in the range of 0.5 mm to 2.5 mm, such as 1.5 mm. The outer diameter of the blood pump may be in the range of 4 mm to 10 mm, preferably 7 mm. The outer diameter of the arrangement of multiple cylinders may be in the range of 3 mm to 8 mm, such as 4 mm to 7.5 mm, preferably 6.5 mm.

[0028] As mentioned above, the column is made of a soft magnetic material such as electrical steel (magnetic steel). The column and the back plate can be made of the same material. Preferably, the drive unit including the column and the back plate is made of cobalt steel. The use of cobalt steel helps to reduce the size of the pump, especially the diameter. With the highest magnetic permeability and the highest saturation flux density among all magnetic steels, cobalt steel produces the most flux for the same amount of material used.

[0029] The dimensions of the cylinder, in particular the length and cross-sectional area, can vary depending on various factors. In contrast to the dimensions of the blood pump, such as the outer diameter, the dimensions of the cylinder are determined by the electromagnetic properties and are adjusted to achieve the desired performance of the drive unit depending on the application of the blood pump. One of the factors is the magnetic flux density that is to be achieved through the minimum cross-sectional area of ​​the cylinder. The smaller the cross-sectional area, the higher the current necessary to achieve the desired magnetic flux. However, the higher the current, the more heat is generated in the wire of the coil due to resistance. This means that although a "thin" cylinder is preferred to reduce the overall size, this will require high current and thus cause undesirable heat. The heat generated in the wire also depends on the length and diameter of the wire used for the coil winding. Short wire lengths and large wire diameters are preferred to minimize winding losses (called "copper losses" or "copper energy losses" if copper wire is used, which is usually the case). In other words, if the wire diameter is small, more heat is generated at the same current compared to thicker wires, so that the preferred wire diameter is, for example, 0.05 mm to 0.2 mm, such as 0.1 mm. Further factors that influence the size of the cylinder 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 cylinder including the windings. A large number of windings may be arranged in more than one layer around each cylinder, for example two or three layers may be provided. However, the higher the number of layers, the more heat generated due to the increased length of the wire with the larger winding diameter in the outer layers. The increased length of the wire may generate more heat due to the higher impedance of the long wire compared to the shorter wire. Therefore, a single-layer winding with a small winding diameter will be preferred. The typical number of windings, in turn, depends on the length of the cylinder and may be from about 50 to about 150, for example 56 or 132. Independently of the number of windings, the coil windings are made of an electrically conductive material, in particular a metal, such as copper or silver. Silver may be preferred over copper because silver has an electrical resistance that is about 5% less than that of copper.

[0030] Preferably, the cylinder has a triangular cross section transverse to the axis of rotation and the soft magnetic sheets of soft magnetic material are preferably oriented in a plane passing through the bisector of the triangular cross section or parallel to the plane. This orientation has the advantage that the longest soft magnetic sheet is arranged in the middle of the cylinder. In the installed state of the cylinder, the bisector can pass through the radially innermost angle of the triangular cross section and preferably further extends through the axis of rotation.

[0031] In another aspect of the present invention, a method for manufacturing a magnetic core, or a part of a magnetic core, for a drive unit of an intravascular blood pump is provided, which comprises the following steps performed in sequence: providing a workpiece comprising, or consisting of, a discontinuous soft magnetic material, the soft magnetic material being discontinuous in terms of electrical conductivity in a cross section of the workpiece and from which the magnetic core, or a part of the magnetic core, is to be manufactured, providing a welding portion on the surface of the workpiece so that the welding portion connects at least one discontinuity in terms of electrical conductivity in the discontinuous soft magnetic material of the workpiece, and separating the magnetic core, or a part of the magnetic core, from the workpiece after providing the welding portion.

[0032] At least a part of the weld may remain at the column after the core or a part of the core is separated from the workpiece.Then, for example, sheets of laminated soft magnetic material may be firmly held together by the weld.

[0033] According to a preferred embodiment, the step of separating the core or a part of the core from the workpiece comprises separating at least one of the cylinders from the workpiece by electrical discharge machining (EDM), in particular by electrical discharge machining of wire cutting. Preferably, before machining the cylinder from the workpiece of soft magnetic material, a dimension of the workpiece is pre-cut to the length of the cylinder so that the pre-cut workpiece has an outer dimension equal to the length of the cylinder. At the end surface defining the length of the cylinder, the weld can be provided before the cylinder is cut out. For example, one or preferably two welds can be arranged to be spaced along each surface of the pre-cut workpiece, which surface will later form the cross-sectional end surface of the cylinder to be cut out from the workpiece. Preferably, all soft magnetic parts of the discontinuous soft magnetic material of the cylinder to be cut out are electrically connected by the weld. The weld can extend over the cross section of more than one cylinder to be cut out from the workpiece. In particular, the weld preferably extends from one edge of the pre-cut workpiece to the opposite edge of the pre-cut workpiece, wherein it also extends through at least one cross section of the cylinder to be cut out. More than one cylinder can be machined from one pre-cut workpiece. The cross sections of the cylinders to be cut out can be appropriately distributed in the pre-cut material to utilize a high percentage of the material. As mentioned above, the discontinuous soft magnetic material of the workpiece can be a laminated material comprising a laminate of soft magnetic sheets. For example, the triangular cross sections of two cylinders to be cut out of the workpiece can be oriented such that the bisector of the angle in each triangular cross section is aligned with the laminate plane of the soft magnetic material, wherein the bisectors are at a distance from each other and the angles of the triangular cross sections having the bisectors point in opposite directions. The above measures contribute to the efficient production of cylinders from the workpiece.

[0034] Preferably, for a triangular column, the weld or welds can be arranged along one triangular side of the triangular cross section of the column. The column can then be mechanically stable due to this side. In this way, the laminated sheets of soft magnetic material can be electrically connected via the weld, preferably all sheets of the column.

[0035] Preferably, at least one weld is produced by laser welding. Double laser welding can also be applied, whereby the weld is welded at least once more. For example, this can help to bridge the gap between two adjacent sheets of laminated soft magnetic material.

[0036] The cut-out magnetic core or a part of a magnetic core, in particular a cut-out cylinder, can be deburred at at least one weld after the magnetic core or a part of a magnetic core has been separated from the workpiece. The burrs may penetrate the electrical insulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The foregoing summary of the invention and the following detailed description of preferred embodiments 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:

[0038] Figure 1 A cross-sectional view of a blood pump is shown;

[0039] Figure 2 A sectional view showing a preferred embodiment of a drive unit - impeller arrangement;

[0040] Figure 3A The perspective view shows the Figure 2 The drive unit - the spacer for the arrangement of the impeller;

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

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

[0043] Figure 4A shows the Figure 2 A perspective view of the first layer of the back plate of the opening of the cylinder of the drive unit;

[0044] Figure 4B shows that there is no Figure 2 A perspective view of the second layer of the back plate of the opening of the cylinder of the drive unit;

[0045] Figure 4C Shown include Figure 4A and Figure 4B A cross-sectional view of an assembled back panel of the first layer and the second layer;

[0046] FIG. 5A to FIG. 5D shows the method for further manufacturing according to Figure 2 The intermediate product manufacturing stage of the arrangement of the cylinder of the drive unit;

[0047] FIG. 6A to FIG. 6C Shown according to Figure 5C Welding parts on intermediate products;

[0048] Figure 7 Shown from FIG. 5A to FIG. 6C A three-dimensional image of a cylinder separated from the prepared intermediate product;

[0049] Figure 8 Shows Fig. 6A A front view on a plane of an intermediate product having two weld seams and two cross sections of a column to be cut out of the intermediate product;

[0050] Fig. 9 A front view showing an end surface of a column having a weld;

[0051] Fig.10 A sectional view showing a second embodiment of a drive unit - impeller arrangement;

[0052] FIG. 11A to FIG. 11C shows the manufacturing method for Fig.10 The step of integrating the magnetic core of the drive unit;

[0053] FIG. 12A to FIG. 12C Shown according to FIG. 11A to FIG. 11C a welded portion on the manufactured integrated magnetic core; and

[0054] FIG. 13A to FIG. 13J A cross section through a cylinder is shown according to various embodiments. DETAILED DESCRIPTION

[0055] refer to Figure 1 , illustrates a cross-sectional view of a blood pump 1. The blood pump 1 includes 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 pump, also called a catheter pump, and is placed in a patient's blood vessel by means of a catheter 25. During use, 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. 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 line 26 extending through the catheter 25 to supply power to the blood pump 1 to drive the pump 1 by means of a drive unit 4, as described in more detail below.

[0056] If the blood pump 1 is intended for long-term use, i.e. a situation where the blood pump 1 is implanted in a patient for weeks or even months, the power is preferably supplied by a battery. This allows patient mobility, 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.

[0057] Blood is transported along a passage 24 connecting a blood flow inlet 21 and a blood flow outlet 22 (arrows indicate blood flow). An impeller 3 is provided for transporting blood along the passage 24 and is mounted to be rotatable about a rotation axis 10 in the pump housing 2 by means of a first bearing 11 and a second bearing 12. The rotation axis 10 is preferably the longitudinal axis of the impeller 3. In this embodiment, both bearings 11, 12 are contact-type bearings. However, at least one of the bearings 11, 12 may be a non-contact-type bearing, such as a magnetic or hydrodynamic bearing. The first bearing 11 is a pivot bearing having a spherical bearing surface that allows rotational movement and pivotal movement to a certain extent. A pin 15 is provided to form one of the bearing surfaces. The second bearing 12 is provided in a support member 13 to stabilize the rotation of the impeller 3, and the support member 13 has at least one opening 14 for blood flow. Blades 31 are provided on the impeller 3 for transporting blood once the impeller 3 rotates. The rotation of the impeller 3 is caused by a drive unit 4 that is magnetically coupled to a magnet 32 ​​at the end portion of the impeller 3. The blood pump 1 shown in the figure is a hybrid blood pump, and its main flow direction is axial. It can be understood that the blood pump 1 can also be a pure axial blood pump, which depends on the arrangement of the impeller 3, especially the blades 31.

[0058] The blood pump 1 comprises an impeller 3 and a drive unit 4. The drive unit 4 comprises a plurality of cylinders 40, such as six cylinders 40. Figure 1 Only two of them can be seen in the cross-sectional view of . The cylinder 40 is arranged parallel to the rotation axis 10, more specifically, the longitudinal axis of each of the cylinders 40 is parallel to the rotation axis 10. One end of the cylinder 42 is arranged adjacent to the impeller. The coil winding 44 is arranged around the cylinder 40. The coil winding 44 is controlled in sequence by a controller to create a rotating magnetic field. Part of the control unit is a printed circuit board 6 connected to the electrical circuit 26. The impeller has a magnet 32, which is formed as a multi-piece magnet in this embodiment. The magnet 32 ​​is arranged at the end of the impeller 3 facing the drive unit 4. The magnet 32 ​​is arranged to interact with the rotating magnetic field to cause the impeller 3 to rotate around the rotation axis 10.

[0059] In order to close the magnetic flux path, a back plate 50 is located at the end of the cylinder 40 opposite to the impeller side of the cylinder. The cylinder 40 acts as a magnetic core and is made of a suitable material, in particular a soft magnetic material, such as steel or a suitable alloy, in particular cobalt steel. Similarly, the back plate 50 is made of a suitable soft magnetic material, such as cobalt steel. The back plate 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, i.e. an additional impeller back plate, is arranged in the impeller 3 on the side of the magnet 32 ​​facing away from the drive unit 4. The yoke 37 has a conical shape in this embodiment to guide the blood flow along the impeller 3. The yoke 37 can also be made of cobalt steel. One or more flushing channels extending toward the center bearing 11 can be formed in the yoke 37 or the magnet 32.

[0060] Figure 2 Shown is the Figure 1 A cross-sectional view of a preferred embodiment of the arrangement of the drive unit-impeller of a blood pump. Figure 2 As shown, the impeller-side end 420 of the cylinder 40 does not extend radially beyond the winding 44. Instead, the cross section of the cylinder 40 is constant in the direction of the longitudinal axis LA of the cylinder 40. This avoids the cylinders 40 coming close to each other, since this would cause local magnetic short circuits and, as a result, reduce the power of the electric motor of the blood pump.

[0061] according to Figure 2 The drive unit 4 may include at least two, at least three, at least four, at least five or preferably six cylinders 40. A greater number of cylinders 40, such as nine or twelve, is possible. Due to the cross-sectional view, only two cylinders 40 can be seen. The cylinders 40 and the back plate 50 form the magnetic core 400 of the drive unit 4, which may have a diameter of less than 10 mm.

[0062] As shown in the figure, the column 40 can be composed of a discontinuous soft magnetic material that is discontinuous in conductivity. The discontinuous soft magnetic material includes a plurality of sheets 85 made of ferromagnetic material and stacked on each 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 in the figure, the column 40 is arranged parallel to the rotation axis 10.

[0063] The spacer 7 is arranged around the cylinder 40. It is made of non-magnetic material and is intended to keep the distance between the cylinders 40 constant at the impeller-side end 420 of the cylinder 40. The spacer 7 will FIG. 3A to FIG. 3C The impeller-side end 424 of the coil winding 44 extends upward to the spacer 7. A back plate 50 is arranged at the other end of the column 40. Figure 2 In the embodiment shown, the back plate 50 has a recess for receiving the column 40 therein. More specifically, it includes a first layer 51 having an opening 511 for the rear end 450 of the column 40. The back plate 50 will be FIG. 4A to FIG. 4C Describe in more detail.

[0064] It is conceivable to realize an embodiment of the blood pump 1 having any combination of the above-mentioned features: the impeller-side end 424 of the cylinder does not radially extend beyond the impeller-side end of the winding 44, a non-magnetic spacer 7 is arranged between the cylinders 40, and the back plate 50 has a recess for receiving the rear end 450 of the cylinder 40.

[0065] FIG. 3A to FIG. 3CA perspective view, a front view and a side view of the spacer 7 are shown respectively. The spacer 7 generally has the form of a disk or a wheel with a through hole 75 in the middle. The spacer 7 includes an opening 71 for each of the cylinders. For an embodiment with six cylinders 40, six openings 71 exist as shown. Between the openings 71, there are spaced spokes 72. When the cylinders 40 are inserted into the openings 71, the spaced spokes 72 keep the distance between the cylinders 40 constant. Further, the spacer 7 includes an outer ring 73 and an inner ring 74 that connect adjacent spaced spokes 72 and stabilize the spacer. The spacer 7 is made of titanium, which is a paramagnetic material, avoiding magnetic short circuits when arranged between the impeller-side ends 420 of the cylinders 40. Titanium provides high mechanical strength so that the spacer 7 with a small thickness can be manufactured. This is advantageous considering the construction space occupied.

[0066] Figure 4A A three-dimensional 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 central hole 515. The first layer 51 includes an opening 511, into which the rear end 450 of the cylinder 40 is to be arranged. The first layer 51 includes spaced spokes 512 arranged between the openings 511. One purpose of the spaced spokes 512 is to keep the distance between the rear end 450 of the cylinder 40 constant from each other. Further, the first layer 51 includes an outer ring 513 and an inner ring 514 connecting the spaced spokes 512 at the radial outer end and the radial inner end of the opening 511, respectively. The first layer 51 can be made of a discontinuous soft magnetic material that is discontinuous in conductivity. It can be composed of a plurality of ferromagnetic sheets 85, in particular three sheets, such as Figure 4A As shown. The sheet 85 is laminated with the non-conductive material to form a discontinuous soft magnetic material. The lamination direction DL is generally parallel to the sheet 85, and the main extension direction of the sheet defines the lamination plane. In the back plate 50, the sheet 85 is perpendicular to the rotation axis 10. In the middle of the first layer 51, a hole 515 is arranged. Its function can be to facilitate the assembly of the first layer 51 and the second layer 52, for example, to center the first layer 51 and the second layer 52.

[0067] exist Figure 4B, a stereoscopic view of the second layer 52 of the back plate 50 is shown. The second layer 52 is essentially in 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 cylinder 40. Instead, the second layer 52 has a contact plane 526 facing the rear end 450 of the cylinder 40. The rear end 450 of the cylinder 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 cylinder 40 and the back plate 50. When all the rear ends 450 of the cylinder 40 are in contact with the contact plane 526, the magnetic flux can be exchanged between the cylinders 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 conductivity and may include sheets 85 stacked together, similar to the structure described above with respect to the first layer 51. As an example, as Figure 4B The three sheets 85 shown may constitute the second layer 52. In the second layer 52, the stacking direction DL 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 amounts by a change in magnetic flux. The hole 525 in the middle of the second layer 52 may have the effect of facilitating the assembly of the first layer 51 with the second layer 52, for example, centering the first layer 51 and the second layer 52.

[0068] Figure 4CA cross section of a back plate 50 is shown. It is composed of a first layer 51 and a second layer 52 bonded to each other at a main surface having the largest extension. The bond between the first layer 51 and the second layer 52 of the back plate 50 can be established in the same manner as between the sheets 85 of the first layer 51 and the second layer 52. The through holes 515 of the first layer 51 and the through holes 525 of the second layer 52 are aligned with each other to center the first layer 51 and the second layer 52. By stacking the first layer 51 and the second layer 52, the opening 511 is closed at one end by the second layer 52 so that a recess 501 is formed to accommodate the rear end 450 of the column 40. On the bottom surface of the recess 501, a contact plane 526 is formed. When the column 40 is inserted into the recess 501, its rear end 450 contacts the contact plane 526. Moreover, the position of the cylinder 40 is fixed by the spaced spokes 512 and the outer ring 513 and the inner ring 514, which together surround each of the cylinders 40. In this way, a magnetic connection is established between the second layer 52 and the rear end surface 45 of the cylinder 40 at the contact plane 526, and additionally, a second magnetic connection is established between the cylinder 40 and the surrounding portion of the above-mentioned first layer 51. However, most of the magnetic flux is transferred via the contact plane 526. Preferably, the surface at the rear end 450 of the cylinder 40 has a predefined flatness and the contact plane 526 also has a predefined flatness. In this way, the gap between the surface 45 at the rear end 450 of the cylinder 40 and the contact plane 526 can be kept below a certain size, preferably less than 10 μm. This improves the transfer of magnetic flux between the cylinder 40 and the back plate 50. Preferably, there is no additional material between the surface 45 at the rear end 450 of the cylinder 40 and the contact plane 526. In this embodiment of the invention, the transfer of magnetic flux via the surface 45 and the backing plate 50 is independent of the manner in which the post 40 is fastened to the backing plate 50 .

[0069] FIG. 5A to FIG. 5D Preparatory steps for producing the column 40 are shown. Figure 5A A perspective view of a plate 8 of a discontinuous soft magnetic material which is discontinuous in terms of electrical conductivity, also referred to below as workpiece, is shown.

[0070] exist Figure 5A In FIG. 8 , 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 5A The enlarged view of the portion indicated by the rectangle R in FIG. Figure 5B Here, 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 a stacking plane.

[0071] Figure 5C A workpiece bar 81 is shown cut from a plate 8 as a single, discrete piece of material. Figure 5C The enlarged view of the portion indicated by the rectangle R in FIG. Figure 5D The sheet 85 of the workpiece bar 81 can be seen in this enlarged view.

[0072] Fig. 6A Shows Figure 5C and Figure 5D The workpiece rod 81 forms the basis for the welding step in the preparatory process of cutting the cylinder 40 out of the rod 81. Fig. 6A On the side plane on the left side in the figure, a plurality of cross sections 84 of the column 40 to be manufactured from the rod 81 are drawn. The column 40 is manufactured by cutting these cross sections 84 out of 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 rear end 450 and the impeller-side end 420 of the column 40.

[0073] Figure 6B The next pre-preparation step before cutting out the cylinder 40 is shown. Two welds 82 and 83 are welded on the face 811 of the rod 81 at a distance from each other and pass through each of the cross sections 84 of the cylinder 40 to be cut out. The welds 82 and 83 extend perpendicularly to the stacking 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, similar welds 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 the welds 82 and 83, and are also electrically connected. The latter has the advantage that the current can flow from any position of the discontinuous soft magnetic material that is expected to become the cylinder 40 to the position of each electrical connection of the rod 81 that can be required, for example, for electrical discharge machining. In this way, electrical discharge machining becomes significantly easier. Moreover, a higher processing reliability is achieved because the cut cylinder 40 will not fall apart due to delamination. Preferably, laser welding is applied. It may be advantageous to apply welding power twice or more to the same weld. The portion of the rod 81 indicated by the rectangle R is Figure 6C Shown enlarged in .

[0074] therefore, Figure 6C A plurality of cross sections 84 of a cylinder 40 to be cut from a rod 81 are shown. The cross sections 84 have a substantially triangular shape. As shown, the corners may be rounded. Figure 6C The convex side 842 shown on the left side of the section 84 has a convex form. This type of section 84 is advantageous in order to fully utilize the available construction space inside the cylindrical pump housing 2. The bisector of the angle 841 of the section 84 opposite to the convex side 842 of the section 84 is aligned with the stacking direction DL. In this way, the sheet 85 extends symmetrically through the section 84.

[0075] Figure 7The cylinder 40 is shown having been cut from the rod 81. As can be seen from the surface 45 at the rear end 450 of the rod 81, the welds 82 and 83 are still present on this surface. The cylinder 40 has a cross section 84 that is constant along its entire length. The welds 82 and 83 are deburred after the cylinder 40 is cut.

[0076] Figure 8 Another arrangement of two sections 84 on the side 811 of the workpiece bar 81 is shown. FIG. 6A to FIG. 6C Compared with the workpiece rod 81 shown in FIG. Figure 8 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 section 84 is oriented relative to the stacking direction DL so that the bisector B of the angle opposite to its respective convex side edge 842 of each section 84 is aligned with the stacking direction DL. By arranging the section 84 along the rod 81 in this way, material can be saved. Less waste material is generated. It is conceivable that, depending on the thickness of the rod 81 and the required cross-sectional dimensions of the cylinder 40, even more sections 84 of the cylinder 40 are stacked in a direction perpendicular to the stacking direction DL. The welds 82 and 83 both extend through each of the sections 84. The welds 82, 83 also extend through the entire side 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.

[0077] Fig. 9 FIG. 8 shows an example of a column 40 cut out from a welded rod 81, namely a front view of one of the end surfaces of the column 40. Fig. 9 As shown, a single weld 86 of considerable width can cover more than about one third of the height of the triangular cross section 84, which extends along the convex side 842 of the cross section 84. The weld 86 extends perpendicular to the stacking direction DL to connect all the sheets thereof. The bisector B of the angle 841 opposite to the convex side 842 is also aligned with the stacking direction DL.

[0078] Fig.10 Shown is the Figure 1 A second embodiment of the arrangement of the drive unit-impeller of the blood pump 1. Figure 2 In the first embodiment shown in FIG, the impeller-side end 420 of the cylinder 40 does not extend radially beyond the winding 44. Instead, the cross section of the cylinder 40 is constant in the direction of the longitudinal axis LA of the cylinder 40. It is thus avoided that the cylinders 40 come close to each other, since this would cause local magnetic short circuits and, as a result, reduce the power of the electric motor of the blood pump.

[0079] according to Fig.10The drive unit 4 may include at least two, at least three, at least four, at least five or preferably six cylinders 40. A greater number of cylinders 40 such as eight, ten or twelve is possible. Due to the cross-sectional view, only two cylinders 40 can be seen. The cylinders 40 and the back plate 50 form the magnetic core 400 of the drive unit 4, which may have a diameter of less than 10 mm.

[0080] This implementation Figure 2 The difference of the first embodiment shown in the figure is 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 whole, the magnetic components are the column 40 and the back plate 50. The whole is made of discontinuous soft magnetic material. The discontinuous soft magnetic material is discontinuous in terms of conductivity. As shown in the figure, it includes a plurality of sheets 85 of ferromagnetic material, which are stacked on each other to form a Fig. 11C The whole 9 is shown. The stacking direction DL is parallel to the axis of rotation 10.

[0081] The coil winding 44 extends upward to the impeller-side end 420 of the cylinder 40. This has the advantage that a magnetomotive force can be generated along the complete cylinder 40. The magnetic core 400 includes a protrusion 401 protruding radially from the cylinder 40 at the rear end 450 of the cylinder 40. This protrusion 401 can be a stop for the coil winding 44 toward the back plate 50. Since the integral magnetic core 400 has high rigidity between the back plate 50 and the cylinder 40, the spacer between the cylinder 40 at the impeller-side end 420 of the cylinder can be omitted. The integral magnetic core 400 provides the advantage that an optimal magnetic connection between the cylinder 40 and the back plate 50 can be achieved. The magnetic core 400 can have a diameter of less than 10 mm.

[0082] FIG. 11A to FIG. 11C Shown is the manufacturing method for Fig.10 The arrangement of the drive unit-impeller of the magnetic core 400 of the drive unit 4 is shown in the steps. Fig.11A A cube-shaped monolith 9 is shown in a perspective view, which forms a workpiece for manufacturing a magnetic core 400. The monolith 9 is composed of a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity. It comprises sheets 85 oriented in a lamination direction DL, which extends along the main plane of the sheet 85. The sheets 85 are each bonded to their respective adjacent sheets by a bonding layer of a non-conductive material, which is FIG. 11A to FIG. 11C Not explicitly shown.

[0083] Fig. 11B The magnetic core 400 is shown in a semi-manufactured state after being processed, for example, from a cubic body 9 to a substantially cylindrical body 94. In this processing step, the protrusion 401 is manufactured. The reduced diameter section 404 of the body 94 forms the outer edge surface of the column 40 of the magnetic core 400, which is manufactured to have a diameter corresponding to the outer diameter of the outermost convex side surface 842 of the column 40.

[0084] The body 94 can then be further manufactured to produce Fig. 11C The magnetic core 400 shown. For this production step, electrical discharge machining can be used. In particular, electrical discharge machining by wire cutting can be applied to produce gaps 49 that separate the cylinders 40 from each other. Inside the gaps, space is provided for the coil windings 44. At the bottom of the gaps 49, the middle region 59 of the integral back plate 50 extends between the rear ends of the cylinders 40. This middle region is integral with the cylinders 40 and with the back plate 50. Thus, the entire magnetic core is formed by the integral body 9.

[0085] The lamination direction DL in the magnetic core 400 is such that it is parallel to the rotation axis 10. It is acceptable that the lamination direction DL in the base plate 50 is not parallel with respect to the magnetic flux between the columns 40 in the base plate 50. It is also possible to manufacture the magnetic core 400 from wound soft magnetic sheet material separated by non-conductive layers. Then, the lamination direction DL in the base plate 50 is always in the circumferential direction, which is advantageous for avoiding eddy currents of the magnetic flux in the base plate 50.

[0086] FIG. 12A to FIG. 12C shows how one or more welds may be arranged in accordance with FIG. 11A to FIG. 11C On the surface of the manufactured integrated magnetic core. Accordingly, in one embodiment shown, three welds 82, 83 are arranged on one side of the cubic whole 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 whole 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 wide weld can be provided. In addition, similar welds can be provided on the opposite side of the whole 9 (not shown). Instead of the welds on the opposite side or in addition to the welds on the opposite side, one or more welds can be provided on the side surface of the whole 9 at the horizontal plane of the back plate 50 to completely or at least partially surround the back plate 50. The sheet 85 has a better mechanical connection to each other due to the welds 82 and 83, and is also electrically connected. The advantage of the latter is that the current can flow from any position of the discontinuous soft magnetic material to the position of each electrical connection of the body 94, which can be required for example for discharge machining. In this way, electrical discharge machining becomes significantly easier. Moreover, higher machining reliability is achieved because the back plate-column unit to be cut out from the body 94 does not fall apart due to delamination. Preferably, laser welding is applied. Applying welding power twice or more to the same weld may be advantageous.

[0087] FIG. 13A to FIG. 13J Various embodiments of a column seen in cross-section are illustrated. FIG. 13A to FIG. 13DAn embodiment is shown where the pillar is slotted, ie, formed from a plurality of sheets 171 insulated from one another by an insulating layer 172. The insulating layer 172 may include an adhesive, a lacquer, a porcelain or the like. Fig.13A and Fig. 13B An embodiment is shown where the thickness of the sheet 171 is uniform. The thickness may be in the range of 25 μm to 450 μm. Fig.13A The sheet 171 shown in FIG. Fig. 13B The sheet 171 shown in FIG. 1 is of greater thickness. Fig. 13C The sheets in the column have different thicknesses, with the center sheet having the greatest thickness and the outermost sheets having the smallest thickness. This can be advantageous because eddy currents in the side regions of the column are more critical and can be reduced by thin sheets. Eddy currents in the center region are less critical and a relatively thick center sheet can help improve the magnetic flux. The orientation of the sheets 171 is as follows: Fig.13D The exemplary illustration may be different as long as the soft magnetic material in the illustrated cross section, ie in a cross section transverse to the magnetic flux direction, is discontinuous or interrupted.

[0088] Fig.13E and Fig.13F An embodiment is shown in which the column 141 is formed of a bundle of wires 181 insulated from each other by an insulating material 182. The insulating material 182 may be present as a coating on each of the wires 181 or may be a matrix in which the wires 181 are embedded. Fig.13E In the embodiment, all wires have the same diameter, and in Fig.13F In an embodiment, the center wire has the largest diameter and the outer wires have a smaller diameter, similar to Fig. 13C The embodiment with sheets of different thicknesses shown in FIG. Figure 13G As shown, wires 181 of different diameters can be mixed, which can increase the overall cross-sectional area of ​​the soft magnetic material compared to an embodiment in which all wires have the same diameter. Still alternatively, to further minimize the insulating layer 184 between wires 183, wires 183 can have a polygonal cross-sectional area, such as a rectangle, a square, etc.

[0089] Alternatively, the discontinuous cross-section of the column 141 can be formed by Fig.13I The column 141 may be created by metal particles 185 embedded in a polymer matrix 186 as shown, or by steel wool or other porous structures throughout the insulating matrix. The porous and therefore discontinuous structure of the soft magnetic material may also be produced by a sintering process or a high pressure molding process, wherein the insulating matrix may be omitted because the insulating layer is automatically formed by oxidation of the soft magnetic material when exposed to air. Still alternatively, the column 141 may be formed by a rolled sheet 187 of soft magnetic material, wherein the layers of the rolled sheet 187 are separated by insulating layers 188, as shown. Fig.13JThis also provides a discontinuous cross section in the sense of the present invention, which reduces eddy currents in the column 141 or the column 40 .

Claims

1. A blood pump (1), comprising: A pump housing (2), wherein the pump housing (2) has 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 for conveying 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) and a back plate (50) connected to rear ends (450) of the columns (40), wherein the columns (40) and the back plate (50) form a magnetic core (400) of the drive unit (4); and a coil winding (44) disposed around each of the cylinders (40), the coil winding (44) being controllable to create 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, It is characterized in that the magnetic core (400) or a part thereof includes a discontinuous soft magnetic material which is discontinuous in conductivity in a cross section or is composed of a discontinuous soft magnetic material which is discontinuous in conductivity in a cross section, wherein at least one welding portion (82, 83, 86) is arranged on a surface (811) of the discontinuous soft magnetic material, and the welding portion (82, 83, 86) connects at least one discontinuity in conductivity in the discontinuous soft magnetic material.

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

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

4. A blood pump (1) according to claim 1, wherein at least one of the at least one weld (82, 83, 86) is arranged on the impeller-side end surface of the cylinder (40) and at least one other weld (82, 83, 86) is arranged on the rear end surface (45) of the cylinder (40).

5. The blood pump (1) according to any one of the preceding claims, wherein two of the at least one weld (82, 83, 86) are arranged at one end of the cylinder (40) at a distance from each other.

6. The blood pump (1) according to any of the preceding claims, wherein at least one of the at least one weld (82, 83, 86) extends on a side surface of the cylinder (40).

7. The blood pump (1) according to claim 6, wherein the at least one of the at least one weld (82, 83, 86) extending on the side surface of the cylinder (40) at least partially surrounds at least one of the cylinders (40).

8. The blood pump (1) according to any of the preceding claims, wherein more than one of the at least one weld (82, 83, 86) is arranged on the same surface side of the cylinder (40).

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

10. A blood pump (1) according to any one of the preceding claims, wherein at least one of the cylinders (40) comprises a stack of soft magnetic material and the soft magnetic sheets (85) are oriented parallel to the longitudinal axis (LA) of the cylinder (40).

11. A blood pump (1) according to claim 10, wherein at least one of the cylinders (40) has a triangular cross-section (84) in a direction transverse to the rotation axis (10), and the soft magnetic sheet (85) of soft magnetic material is oriented in a plane passing through a bisector (B) of the triangular cross-section (84) or parallel to the plane.

12. A method for producing a magnetic core (400) or a part of a magnetic core (400) for a drive unit (4) of a blood pump (1), characterized in that The following steps are involved: providing a workpiece (8, 81) of discontinuous soft magnetic material which is discontinuous in electrical conductivity in a cross section of the workpiece (8, 81) and from which the magnetic core (400) or a part of the magnetic core (400) is to be manufactured, and At least one welding portion (82, 83, 86) is provided on the surface (811) of the workpiece (8, 81), so that the at least one welding portion (82, 83, 86) connects at least one discontinuity in conductivity in the discontinuous soft magnetic material of the workpiece (8, 81).

13. The method according to claim 12, wherein the magnetic core (400) or a portion of the magnetic core (400) is separated from the workpiece (8, 81) after providing the at least one weld.

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

15. The method according to claim 13 or 14, wherein the step of separating the magnetic core (400) or a portion of the magnetic core (400) from the workpiece (8, 81) comprises separating at least one column (40) of the magnetic core (400) from the workpiece (8, 81) by electrical discharge machining.

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

17. The method according to any one of claims 12 to 16, wherein the at least one weld (82, 83, 86) comprises a weld seam bridging the at least one discontinuity in electrical conductivity in the discontinuous soft magnetic material.

18. The method according to any one of claims 12 to 17, wherein the magnetic core (400) comprises a plurality of columns (40) arranged around a rotation axis (10) and a back plate (50) connecting rear ends (450) of the plurality of columns (40).

19. The method according to claim 18 comprises the following steps: connecting a portion of the magnetic core (400) separated from the workpiece (8, 81) to the back plate (50) to form one of the multiple columns (40) of the magnetic core (400), wherein the at least one welding portion (82, 83, 86) is arranged at an end surface (45) of a rear end portion (450) of the one of the multiple columns (40).

20. The method according to claim 18 or 19, wherein at least one of the at least one weld (82, 83, 86) is arranged on an impeller-side end surface of the cylinder (40).

21. The method according to any one of claims 18 to 20, wherein two of the at least one welding portion (82, 83, 86) are arranged at one end of the cylinder (40) at a distance from each other.

22. The method according to any one of claims 18 to 21, wherein at least one of the at least one weld (82, 83, 86) extends on a side surface of the column (40).

23. The method of claim 22, wherein the at least one of the at least one weld (82, 83, 86) extending on the side surface of the pillar (40) at least partially surrounds at least one of the pillars (40).

24. The method according to any one of claims 18 to 23, wherein more than one of the at least one weld (82, 83, 86) is arranged on the same surface side of the column (40).

25. The method according to any one of claims 18 to 24, wherein at least one column (40) of the plurality of columns (40) comprises a stack of soft magnetic material and the soft magnetic sheet (85) is oriented parallel to the longitudinal axis (LA) of the column (40).

26. A method according to claim 25, wherein at least one of the cylinders (40) has a triangular cross-section (84) in a direction transverse to the rotation axis (10), and the soft magnetic sheet (85) of soft magnetic material is oriented in a plane passing through a bisector (B) of the triangular cross-section (84) or parallel to the plane.

27. The method according to any one of claims 12 to 26, wherein the blood pump (1) is a blood pump according to any one of claims 1 to 11.

28. The method according to claim 27, wherein the blood pump (1) is an intravascular blood pump.

29. A blood pump (1), comprising: A pump housing (2), wherein the pump housing (2) has 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 for conveying 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) and a back plate (50) connected to rear ends (450) of the columns (40), wherein the columns (40) and the back plate (50) form a magnetic core (400) of the drive unit (4); and a coil winding (44) disposed around each of the cylinders (40), the coil winding (44) being controllable to create 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, and The magnetic core (400) or a portion thereof comprises or is composed of a discontinuous soft magnetic material that is discontinuous in electrical conductivity in a cross section, wherein: The cylinder is formed from a bundle of wires insulated from one another by an insulating material, wherein the bundle of wires comprises wires of mixed different diameters to increase the overall cross-sectional area of ​​the soft magnetic material compared to an embodiment in which all wires in the bundle of wires have the same diameter, or The cylinder is formed from a rolled sheet of soft magnetic material.

30. The blood pump (1) according to claim 29, 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 at least one discontinuity in conductivity in the discontinuous soft magnetic material.

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