Blood pump

Abstract

The present invention relates to an intravascular blood pump for percutaneous insertion into a blood vessel of a patient. 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 includes a drive unit for rotating an impeller, the drive unit including a magnetic core including a plurality of cylinders arranged about an axis of rotation and a back plate connecting the cylinders and extending between the cylinders in an intermediate region. A coil winding is disposed around each of the cylinders. The coil windings can be controlled to create a rotating magnetic field, wherein the impeller comprises a magnetic structure arranged to interact with the rotating magnetic field to cause the impeller to rotate. The material of at least a portion of at least one of the posts is integral with the material of the intermediate region of the back plate. The invention further relates to a method for producing a magnetic core and to a method for producing an intravascular blood pump.

Description

[0001] Divisional application

[0002] This application is a divisional application of the patent application with application number 202080022899.0, 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 / 0238172A1 discloses an extracorporeal blood pump having an impeller that can be magnetically coupled to an electric motor. The impeller includes a magnet that is arranged adjacent to a magnet in the electric motor. Due to the attraction between the impeller and the magnet in 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, but this 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 having a blood flow inlet and a blood flow outlet, an impeller, and a drive unit for rotating the impeller. By rotating 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 magnetic core, which includes a plurality of, preferably six, cylinders and a back plate connecting the rear ends of the cylinders to act as a yoke. When viewed in a plane perpendicular to the rotation axis, the cylinders are arranged in a circle around the rotation axis, wherein each cylinder has a longitudinal axis, which is preferably parallel to the rotation axis. The back plate has a through opening, and the rear end of the cylinder is received in each of the through openings in a fitting manner, so that the end surface of the rear end of each cylinder is flush with the rear surface of the back plate. In this way, a magnetic connection between the cylinder and the back plate is generated between the circumference of the cylinder and the inner contour of the opening of the back plate. The cylinders each have a coil winding arranged around the 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 comprises a magnetic structure in the form of a magnet arranged to interact with a rotating magnetic field so that the impeller rotates with it.

[0008] It is an object of the present invention to increase the magnetic flux in a magnetic core. Summary of the invention

[0009] The blood pump of the invention corresponds to the blood pump described above. 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 generally too large for intravascular applications). However, according to one aspect of the invention, the material of at least a portion of at least one of the columns of the magnetic core is integral with the material of the middle region of the back plate of the magnetic core, wherein the middle region of the back plate is the region of the back plate located between the columns. Preferably, all columns are integrally connected to the back plate in this way. In other words, at least one column and the back plate, preferably the entire magnetic core, can be made of a single piece of material, hereinafter also referred to as a monoblock. One advantage of such a magnetic core is that the magnetic resistance at the transition between the column and the back plate is minimized and the magnetic flux is therefore increased. In addition, good mechanical stiffness at the transition between the column and the back plate can be achieved.

[0010] Each of the cylinders has a longitudinal axis that is parallel to the axis of rotation. Preferably, the magnetic core comprises a discontinuous soft magnetic material. More preferably, the soft magnetic material of the magnetic core is discontinuous in a cross section that is transverse to, preferably perpendicular to, the longitudinal axis of the 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 windings 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 to the patient. Moreover, in long-term applications, the blood pump can be operated without emptying, which is only possible when the heat generation is low.

[0011] "Discontinuous" in the sense of this application document means that the soft magnetic material seen in any cross-section transverse to, for example, the longitudinal axis of a cylinder 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.

[0012] 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.

[0013] The sheet preferably extends substantially parallel to the longitudinal axis of the corresponding 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 corresponding 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 about 450 μm, for example 200 μm.

[0014] In particular, a region of a certain type of material, such as a sheet of soft magnetic material, may extend in both the pillars and the back plate. Although the material is discontinuous, the core may be made of a single piece of this material. The extension of this region of a certain type of material is not interrupted by the transition between the pillars and the back plate, but is integrally continuous from the pillars to the intermediate region of the back plate located between the pillars.

[0015] It is 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 cylinder. For example, instead of a plurality of sheets, a plurality of wires, fibers, cylinders or other elongated elements may be provided to form each cylinder 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 materials, such as adhesives, lacquers, polymer matrices, and the like. The porous and therefore discontinuous structure of the soft magnetic material may also be formed by sintering or pressing materials. 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 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 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.

[0019] 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.

[0020] 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, for example the outer diameter depends on the application of the blood pump, the dimensions of the cylinder are determined by the electromagnetic properties and are adjusted to achieve the desired performance of the drive unit. 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 the usual 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.

[0021] Preferably, the magnetic core comprises one or more welds. The welds may be arranged on an outer surface of the magnetic core, which is particularly accessible for example for laser welding. The welds bridge discontinuities in the electrical conductivity in the soft magnetic material and thus electrically connect at least two sheets of soft magnetic material. The welds also add mechanical stability to the discontinuous soft magnetic material.

[0022] One or more welds may be arranged on the surface of the back plate opposite to the cylinder. They may be produced by laser welding. In the case of using a material made of laminated sheets, the welds preferably join adjacent soft magnetic sheets obliquely or laterally.

[0023] In another aspect of the invention, a method of manufacturing a magnetic core for a drive unit of an intravascular blood pump is provided. The magnetic core has an axis of rotation and includes a plurality of cylinders arranged about the axis of rotation and a back plate connecting the cylinders. The method includes the steps of providing a unitary piece of magnetically conductive material and cutting slits in the unitary piece to construct the cylinders and the back plate, so that the cylinders are arranged about the axis of rotation and the back plate is formed as a single piece with the cylinders. As noted above, one advantage of such manufacturing is the production of a magnetic core with reduced magnetic resistance.

[0024] At least one slit, preferably all slits, which are mutually opposite with respect to the axis of rotation, can be produced by cutting through the axis of rotation of the magnetic core. Then, a uniform distribution of the cylinders around the axis of rotation can be easily achieved. Preferably, the slits are cut so that the cylinders all have equal length. The slits are in particular cut so that the backing plate has a thickness that is smaller than the largest cross-sectional dimension of the cylinder transversely to its longitudinal axis.

[0025] Preferably, the slits are cut using electrical discharge machining, in particular wire electrical discharge machining, or using electrochemical machining. These methods exert only low forces on the material to be machined and are therefore particularly advantageous for machining discontinuous materials.

[0026] In a further aspect of the present invention, a method for manufacturing a blood pump is provided. The blood pump comprises a drive unit having a magnetic core, wherein the magnetic core is manufactured in the manner described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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:

[0028] Figure 1 A cross-sectional view of a blood pump is shown;

[0029] Figure 2 A sectional view showing a preferred embodiment of a drive unit - impeller arrangement;

[0030] FIG. 3A to FIG. 3C shows the manufacturing method for Figure 2 The steps of integrating the magnetic core of the drive unit;

[0031] FIG. 4A to FIG. 4C Shown as FIG. 3A to FIG. 3C A welded portion on the manufactured integrated magnetic core; and

[0032] FIG. 5A to FIG. 5J A cross section through a cylinder is shown according to various embodiments. DETAILED DESCRIPTION

[0033] 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 that 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.

[0034] 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, e.g. wirelessly.

[0035] 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 of some degrees. 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 3 of the impeller 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 is 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.

[0036] 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 1Only 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The magnetic core 400 comprises the magnetic components of the drive unit 4 as a single piece or whole piece, the magnetic components being the cylinder 40 and the back plate 50. The whole piece is made of a discontinuous soft magnetic material that is discontinuous in terms of conductivity. The discontinuous soft magnetic material comprises a plurality of sheets 85 made of ferromagnetic material and stacked one on another. The stacking direction is arranged in the direction of the longitudinal axis LA of the cylinder 40 and is indicated by the arrow DL. As shown in the figure, the cylinder 40 is arranged parallel to the rotation axis 10.

[0041] 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 the end point of the coil winding 44 toward the back plate 50. Because the integrated 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 integrated 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.

[0042] FIG. 3A to FIG. 3C Shown is the manufacturing method for Figure 2 The arrangement of the drive unit-impeller of the magnetic core 400 of the drive unit 4 is shown in the steps. Figure 3A 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 non-conductive material, which is FIG. 3A to FIG. 3C Not explicitly shown.

[0043] Figure 3B The magnetic core 400 is shown in a semi-manufactured state after having been processed, for example, from a cubic monolithic piece 9 into a substantially cylindrical body 94. In this machining step, the protrusion 401 is manufactured. The reduced diameter section 404 of the body 94 forms the outer edge surface of the cylinder 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 cylinder 40.

[0044] The body 94 can then be further manufactured to produce Figure 3CThe 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 the gap 49 that separates the cylinders 40 from each other. Inside the gap, space is provided for the coil winding 44. At the bottom of the gap 49, the middle area 59 of the integral back plate 50 extends between the rear ends of the cylinders 40. This middle area is integral with the cylinders 40 and with the back plate 50. Thus, the entire magnetic core is formed by a single piece 9.

[0045] 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.

[0046] FIG. 4A to FIG. 4C shows how one or more welds may be arranged in accordance with FIG. 3A to FIG. 3C 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 across 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.

[0047] FIG. 5A to FIG. 5J Various embodiments of a column seen in cross-section are illustrated. FIG. 5A to FIG. 5D An 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. Figure 5A and Figure 5BAn 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. Figure 5A The sheet 171 shown in FIG. Figure 5B The sheet 171 shown in FIG. 1 is of greater thickness. Figure 5C 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: Figure 5D 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.

[0048] Figure 5E and Fig. 5F 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. Figure 5E In the embodiment, all wires have the same diameter, and in Fig. 5F In an embodiment, the center wire has the largest diameter and the outer wires have a smaller diameter, similar to Figure 5C The embodiment with sheets of different thicknesses shown in FIG. Figure 5G 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.

[0049] Alternatively, the discontinuous cross-section of the column 141 can be formed by Fig.5I 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. Figure 5J This 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 magnetic core (400), the magnetic core (400) comprising a plurality of columns (40) arranged around the rotation axis (10) and a back plate (50) connecting the columns (40), wherein the back plate (50) has a middle area (59) extending between the columns (40), 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, wherein at least a portion of at least one of the columns (40) is formed as an integral piece with the middle region (59) of the back plate (50), wherein the one-piece is machined from a solid piece (9) to construct a cylindrical body (94), and slits are cut into the cylindrical body (94) to construct the column (40), wherein the integral part comprises or is composed of a soft magnetic material which is discontinuous in electrical conductivity in a cross section transverse to the rotation axis (10), The soft magnetic material comprises a stack of laminated sheets (85) of soft magnetic material.

2. The blood pump (1) according to claim 1, wherein the sheet (85) of soft magnetic material is oriented parallel to the rotation axis (10).

3. The blood pump (1) according to claim 1, comprising at least one weld (82, 83, 86), which bridges a discontinuity in electrical conductivity in the soft magnetic material.

4. The blood pump (1) according to claim 3, wherein at least one of the at least one weld (82, 83, 86) is arranged on a surface of the back plate (50) opposite to the column (40).

5. The blood pump (1) according to claim 3, wherein at least one of the at least one welding portion is arranged on an end surface of the column (40) opposite to the back plate (50).

6. A method for manufacturing a magnetic core (400) for a drive unit (4) of a blood pump (1), wherein the magnetic core (400) has a rotation axis (10) and comprises a plurality of cylinders (40) arranged around the rotation axis (10) and a back plate (50) connecting the cylinders (40), the method comprising the steps of: machining a whole piece (9) of magnetically conductive material from a larger workpiece, wherein the whole piece (9) comprises or consists of a soft magnetic material which is discontinuous in electrical conductivity in a cross section transverse to the axis of rotation (10), wherein the soft magnetic material comprises a stack of laminated sheets (85) of soft magnetic material, transforming the monolith (9) into a cylindrical body (94), Slits are cut in the cylindrical body (94) to construct the column (40) and the back plate (50), so that the column (40) is arranged around the rotation axis (10) and the back plate (50) is formed as a single piece with the column (40).

7. The method according to claim 6, wherein at least one of the slits (49) is cut through the rotation axis (10).

8. The method of claim 6, wherein the slits (49) are cut so that the pillars (40) are all of equal length.

9. The method according to claim 6, wherein the slits (49) are cut so that the back plate (50) has a thickness that is smaller than the largest cross-sectional dimension of the column (40) transverse to its longitudinal axis (LA).

10. The method of claim 6, wherein the slits (49) are cut using electrical discharge machining.

11. The method of claim 6, wherein the slits are cut using wire cutting by electrical discharge machining.

12. The method of claim 6, wherein the slits are cut using electrochemical machining.

13. The method of claim 6, wherein the laminated sheets (85) of soft magnetic material are oriented parallel to the axis of rotation (10).

14. A method according to claim 6, comprising the step of providing at least one weld (82, 83, 86) to bridge a discontinuity in electrical conductivity in the soft magnetic material.

15. The method according to claim 14, wherein at least one of the at least one weld (82, 83, 86) is arranged on a surface of the back plate (50) opposite to the column (40).

16. The method according to claim 14, wherein at least one of the at least one welding portion is arranged on an end surface of the column (40) opposite to the back plate (50).

17. The method according to claim 14, wherein at least one weld is provided on the larger workpiece before the entire piece (9) is machined from the larger workpiece.

18. The method of claim 14, wherein the step of providing at least one weld (82, 83, 86) to bridge a discontinuity in electrical conductivity in the soft magnetic material is performed prior to the step of cutting a slit in the piece.

19. The method of claim 6, wherein the laminated sheets in the stack of laminated sheets are each bonded to their respective adjacent sheets by a bonding layer of a non-conductive material.

20. A method for producing an intravascular blood pump (1), the intravascular blood pump (1) having a drive unit (4), the drive unit (4) having a magnetic core (400), wherein the magnetic core (400) is produced according to any one of claims 6 to 19.

21. 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), the drive unit (4) being used to rotate the impeller (3), the drive unit (4) comprising a magnetic core (400), the magnetic core (400) comprising a plurality of columns (40) arranged around the rotation axis (10) and a back plate (50) connecting the columns (40), 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, The invention is characterized in that the coil winding (44) comprises 50 to 150 windings arranged in one, two or three layers, wherein the coil winding is made of wire having a wire diameter between 0.05 mm and 0.2 mm.

22. The blood pump (1) according to claim 21, wherein the coil winding (44) comprises 56 or 132 windings.

23. The blood pump (1) according to claim 21, wherein the coil winding (44) is arranged as a single layer.

24. The blood pump (1) according to claim 21, wherein the wire diameter is 0.1 mm.

25. The blood pump (1) according to claim 21, wherein at least one of the cylinders (40) has a diameter in the order of 500 μm.

26. The blood pump (1) according to claim 21, wherein the power input to the drive unit (4) is up to 20 Watts.

27. The blood pump (1) according to claim 21, capable of operating at a speed of up to 50,000 revolutions per minute.

28. A blood pump (1) according to claim 21, wherein the magnetic core (400) includes a soft magnetic material that is discontinuous in conductivity in a cross section transverse to the rotation axis (10), or is composed of a soft magnetic material that is discontinuous in conductivity in a cross section transverse to the rotation axis (10).

29. The blood pump (1) according to claim 28, wherein the soft magnetic material comprises a laminated sheet (85) of soft magnetic material.

30. The blood pump (1) according to claim 29, wherein the sheet (85) of soft magnetic material is oriented parallel to the axis of rotation (10).

31. A blood pump (1) according to claim 21, wherein the back plate (50) extends between the columns (40) in a middle region (59), and at least a portion of at least one of the columns (40) is integral with the middle region (59) of the back plate (50).

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