Blood pump

Abstract

The invention relates to an intravascular blood pump, a method for manufacturing a magnetic core and a method for manufacturing a blood pump. The blood pump includes: a pump housing having a blood flow inlet and a blood flow outlet; an impeller is disposed in the pump housing to be rotatable about an axis of rotation. The impeller has blades sized and shaped to deliver blood from the blood flow inlet to the blood flow outlet. The blood pump comprises a drive unit for rotating an impeller, the drive unit comprising a magnetic core comprising a plurality of posts arranged about an axis of rotation and a back plate connecting the posts and extending between the posts in an intermediate region. And a coil winding disposed around each of the posts. 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. Within each of the columns, one of the sheets of soft magnetic material, or an intermediate layer between two of the sheets of soft magnetic material, is arranged in a plane including the axis of rotation.

Description

[0001] Divisional application This application is a divisional application of the patent application with the international application date of September 15, 2021, the application number of 202180065032.8, the entering Chinese national stage date of March 22, 2023, and the invention name of "Blood Pump". TECHNICAL FIELD

[0002] The present invention relates to a blood pump for supporting blood flow in a blood vessel of a patient, in particular to an intravascular blood pump for percutaneous insertion into a blood vessel of a patient. The blood pump has an improved drive unit. BACKGROUND

[0003] Different types of blood pumps are known, such as axial blood pumps, centrifugal (i.e. radial) blood pumps or hybrid blood pumps in which the blood flow is caused by both axial and radial forces. The intravascular blood pump is inserted into a blood vessel of a patient, such as the aorta, by means of a catheter. The blood pump typically comprises a pump housing having a blood flow inlet and a blood flow outlet connected by a passage. In order to cause blood flow along the passage from the blood flow inlet to the blood flow outlet, an impeller or rotor is rotatably supported within the pump housing, wherein the impeller is provided with paddles for transporting blood.

[0004] The blood pump is typically driven by a drive unit, which can be an electric motor. For example, US 2011 / 0238172 A1 discloses an extracorporeal blood pump having an impeller which can be magnetically coupled to an electric motor. The impeller is arranged as a magnet adjacent to a magnet in the electric motor. Due to an attractive force between the magnet in the impeller and the magnet in the electric motor, the rotation of the electric motor is transmitted to the impeller. In order to reduce the number of rotating components, it is also known from US 2011 / 023817 A1 to utilize a rotating magnetic field, wherein the drive unit has a plurality of electrostatic columns arranged around a rotation axis, and each column carries a coil winding and functions as a magnetic core. A control unit sequentially supplies a voltage to the coil windings to create a rotating magnetic field. In order to provide a sufficiently strong magnetic coupling, the magnetic force has to be sufficiently high, which can be achieved by a sufficiently high current supplied to the drive unit or by providing large magnets, however, this results in a large overall diameter of the blood pump.

[0005] EP 3222301 B1 discloses a blood pump having an electromagnetic coupling between a drive unit and an impeller, in particular an intravascular blood pump, wherein the blood pump has a compact design and in particular a high ratio of pumping power to size of the pump resulting in a sufficiently small outer dimension to allow the blood pump to be inserted transvascularly, transvenously, transarterially or transvalvularly or even smaller for operational and convenience reasons.

[0006] 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. Blood can be transported from the blood flow inlet to the blood flow outlet through the impeller blades by rotation of the impeller about an axis of rotation and within the pump housing. The drive unit includes a magnetic core comprising a plurality (preferably six) columns and a back plate connecting the rear ends of the columns as a yoke. Viewed from a plane perpendicular to the axis of rotation, the columns are arranged in a circle around the axis of rotation, wherein each column has a longitudinal axis, preferably parallel to the axis of rotation. The back plate has a through-hole into which the rear end of each column is received in a form-fitting manner, such that the end surface of the rear end of each column is flush with the rear surface of the back plate. Thus, a magnetic connection is created between the column and the back plate between the circumference of the column and the inner contour of the opening of the back plate. Each column has a coil winding arranged around it. To generate a rotating magnetic field for driving the impeller, the coil windings can be controlled in a coherent manner. The impeller includes a magnetic structure in the form of a magnet, which is arranged to interact with a rotating magnetic field so that the impeller follows its rotation.

[0007] One of the objectives of this invention is to increase the magnetic flux in the magnetic core. Summary of the Invention

[0008] The blood pump disclosed herein corresponds to the blood pump described above. Therefore, it can be an axial-flow blood pump or a diagonal blood pump that pumps partially axially and partially radially (the diameter of a purely centrifugal blood pump is typically too large for intravascular applications). However, according to one aspect of this disclosure, at least a portion of the material of at least one column of the magnetic core is integral with the material of the intermediate region of the backplate of the magnetic core, wherein the intermediate region of the backplate is the region of the backplate located between the columns. Preferably, all columns are integrally connected to the backplate in this manner. In other words, at least one column and the backplate, preferably the entire magnetic core, can be made from a single block of material, hereinafter also referred to as a monoblock. The advantage of such a magnetic core is that the magnetic resistance at the transition between the column and the backplate is minimized, and therefore, the magnetic flux is increased. Furthermore, good mechanical rigidity can be achieved at the transition between the column and the backplate.

[0009] Each of the columns has a longitudinal axis, which may be parallel to the axis of rotation. Preferably, the core comprises a discontinuous soft magnetic material. More preferably, the soft magnetic material of the core is discontinuous in a cross-section transversely, preferably perpendicularly, to the longitudinal axis of the column. In other words, the soft magnetic material of the column is discontinuous in a cross-section transversely, preferably perpendicularly, to the direction of the magnetic flux caused by the respective coil windings in the column. By segmenting or discontinuing the soft magnetic material in the cross-section, eddy currents in the column can be reduced or avoided, thereby reducing heat generation and energy consumption. Reduced energy consumption is particularly useful for the long-term application of the blood pump, where it is desirable for the blood pump to be battery-powered to provide mobility to the patient. Furthermore, in long-term application, the blood pump can be operated without purging, which is only possible when heat generation is low.

[0010] In the sense of this invention, "discontinuous" means that the soft magnetic material seen in any cross-section transverse to, for example, the longitudinal axis of a column, is discontinuous, separated, intersecting, or similar by means of insulating or other materials or gaps, forming strictly separated areas of the soft magnetic material or discontinuous areas connected at different locations.

[0011] Providing discontinuous soft magnetic material in the cross-sectional plane transverse to the direction of magnetic flux reduces eddy currents and thus heat generation and energy consumption, as explained above. To avoid substantially weakening the magnetic field compared to continuous or full-body (i.e., solid) soft magnetic material, the total amount of soft magnetic material must be maximized while minimizing continuous regions of soft magnetic material. This can be achieved, for example, by providing soft magnetic material, such as electrical steel, in the form of multiple sheets. Specifically, the sheets can be layered, e.g., laminated, to form a stack of sheets. The sheets are preferably electrically insulated from each other, for example by providing an adhesive, varnish, baked enamel, or similar between adjacent sheets. This arrangement can be referred to as "slotted". Compared to full soft magnetic material, the amount of soft magnetic material is reduced only slightly and the amount of insulating material is kept small, such that the magnetic field caused by slotted columns is substantially the same as that caused by solid columns. In other words, while heat generation and energy consumption can be significantly reduced, the loss of magnetic field caused by insulating materials is insignificant.

[0012] The sheet preferably extends substantially parallel to the longitudinal axes of the respective pillars. In other words, the sheet may extend substantially parallel to the direction of magnetic flux, such that the pillars are discontinuous in cross-sections in the direction transverse or perpendicular to the direction of magnetic flux. It should be understood that the sheet may extend at an angle relative to the longitudinal axes of the respective pillars, provided that the soft magnetic material is discontinuous in cross-sections transverse to the longitudinal axes. 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.

[0013] In particular, regions of a certain type of material, such as sheets of soft magnetic material, can extend within both the posts and the backplate. Although the material is discontinuous, the core can be made from a single block of this material. The extension of such regions of a certain type of material is not interrupted by the transition between the posts and the backplate, but rather continues integrally from the posts to the middle region of the backplate located between the posts.

[0014] It is generally known to provide grooved soft magnetic materials, such as electrical steel, in electric motors to avoid or reduce eddy currents. However, this technique has been applied to large devices in which the sheets typically have thicknesses in the range of about 500 μm or higher. In smaller applications, such as the blood pump of this disclosure, where one of the columns typically has a diameter in the aforementioned order of magnitude, and where the power input is relatively low (e.g., up to 20 watts (W)), eddy currents and associated problems are not expected. Surprisingly, despite the small diameter of the column, eddy currents, and therefore heat generation and energy consumption, can be reduced by providing grooved columns. This is advantageous for the operation of the blood pump, which can be operated at high speeds of up to 50,000 rpm.

[0015] It should be understood that other arrangements besides the grooved arrangement mentioned above are possible for providing discontinuous soft magnetic material in the columns. For example, instead of multiple sheets, multiple wires, fibers, columns, or other elongated elements can be provided to form each of the columns in the drive unit. Wires or the like can be provided in bundles, wherein the wires are electrically insulated from each other, for example by means of a coating surrounding each wire or an insulating matrix in which the wires are embedded, and can have various cross-sectional shapes, such as circular, round, rectangular, square, polygonal, etc. Similarly, granules of soft magnetic material, soft magnetic material yarns, or other sponge-like or porous structures can be provided, wherein the spaces between the regions of soft magnetic material include electrically insulating materials, such as adhesives, varnishes, polymer matrices, or the like. The porous and therefore discontinuous structure of the soft magnetic material can also be formed from sintered or pressed material. In this structure, additional insulating material can be omitted, as the insulating layer can be automatically formed by an oxide layer resulting from the oxidation of the soft magnetic material by exposure to air.

[0016] While sheets or other structures of soft magnetic material can be formed uniformly—that is, sheets within one or all pillars can have the same thickness or lines can have the same diameter—non-uniform arrangements can be provided. For example, sheets can have varying thicknesses or lines can have varying diameters. More specifically, particularly with respect to stacks of sheets, one or more central sheets can have a larger thickness, while adjacent sheets towards the ends of the stack can have a smaller thickness, i.e., the sheet thickness decreases from the center towards the ends of the stack, i.e., the sheet thickness decreases from the center towards the outermost sheets of the stack. Similarly, one or more central lines in a bundle of lines can have a larger diameter, while lines at the edges of the pillars can have a smaller diameter, i.e., the line diameter decreases from the center towards the edge of the bundle, i.e., the line diameter decreases from the center towards the outermost lines of the bundle. Providing a large, continuous region of soft magnetic material in the center of the cross-section of the column relative to its longitudinal axis, i.e., a relatively thick sheet or wire in the center, can be advantageous because this enhances the magnetic flux passing through the center along the longitudinal axis of each column, and the eddy currents in the center are less relevant than those in the sides of the column. In other words, such an arrangement can be advantageous because the eddy currents in the side regions of the column are more critical and can be reduced by the thin sheet or wire in the side regions.

[0017] The diameter of the backplate can be in the range of 3mm to 9mm, for example 5mm or 6mm to 7mm. The thickness of the backplate can be in the range of 0.5mm to 2.5mm, for example 1.5mm. The outer diameter of the blood pump can be in the range of 4mm to 10mm, preferably 7mm. The outer diameter of the arrangement of multiple columns can be in the range of 3mm to 8mm, for example 4mm to 7.5mm, preferably 6.5mm.

[0018] As stated above, the column is made of a soft magnetic material such as electrical steel (magnetic steel). The column and backplate can be made of the same material. Preferably, the drive unit, including the column and backplate, is made of cobalt steel. The use of cobalt steel helps to reduce the pump size, especially the diameter. Cobalt steel has the highest permeability and the highest magnetic saturation flux density of all magnetic steels, producing the most magnetic flux for the same amount of material used.

[0019] The dimensions of the column, particularly its length and cross-sectional area, can vary and depend on various factors. Unlike the dimensions of a blood pump, such as its outer diameter, which depend on the application of the blood pump, the dimensions of the column are determined by its electromagnetic properties and are adjusted to achieve the desired performance of the drive unit. One factor is the flux density to be achieved through the minimum cross-sectional area of ​​the column. The smaller the cross-sectional area, the higher the current required to achieve the desired magnetic flux. However, due to resistance, a higher current generates more heat in the coil wire. This means that while a “thin” column is preferred to reduce the overall size, this will require a higher current and thus result in undesirable heat. The heat generated in the wire also depends on the length and diameter of the wire used for the coil winding. Shorter wire lengths and larger wire diameters are preferred to minimize winding losses (often referred to as “copper losses” or “copper power losses,” which is usually the case if copper wire is used). In other words, if the wire diameter is small, more heat is generated at the same current compared to a thicker wire; a preferred wire diameter is, for example, 0.05 mm to 0.2 mm, e.g., 0.1 mm. Other factors affecting column size and drive unit performance are the number of coil windings and the outer diameter of the column containing the windings. A larger number of windings can be arranged in more than one layer around each column; for example, two or three layers can be provided. However, if the number of layers is higher, more heat will be generated due to the increased length of the wire in the outer layer with a larger winding diameter. The increased wire length can generate more heat because of the higher resistance of longer wires compared to shorter wires. Therefore, a single layer of windings with a smaller diameter is preferred.

[0020] The typical number of windings, depending on the length of the posts, can be from about 50 to about 150, for example, 56 or 132. Independent of the number of windings, the coil windings are made of a conductive material, particularly a metal, such as copper or silver. Silver may be preferred over copper because silver has a resistance that is about 5% lower than that of copper.

[0021] Preferably, the magnetic core includes one or more welded portions. The welded portions can be disposed on the outer surface of the magnetic core, which is particularly convenient for, for example, laser welding. The welded portions bridge discontinuities in conductivity within the soft magnetic material, and thus electrically connect at least two sheets of the soft magnetic material. The welded portions also increase the mechanical stability of the discontinuous soft magnetic material.

[0022] One or more welded sections can be provided on the surface of the backplate opposite to the column. These can be formed by laser welding. In the case of materials made of laminated sheets, the welded sections preferably bridge adjacent soft magnetic sheets obliquely or laterally.

[0023] In another aspect of this disclosure, a method for manufacturing a magnetic core for a drive unit of an intravascular blood pump is proposed. The magnetic core has a rotation axis and includes a plurality of posts arranged around the rotation axis and a back plate connecting the posts. The method includes providing a monolith of magnetically conductive material and cutting slots in the monolith to form posts arranged around the rotation axis and a back plate forming an integral component with the posts. As described above, the advantage of this manufacturing method is that it can produce a magnetic core with reduced magnetic reluctance.

[0024] At least one slot, preferably all slots opposite each other relative to the axis of rotation, can be created by cutting through the axis of rotation of the magnetic core. Thus, a uniform distribution of the columns around the axis of rotation can be easily achieved.

[0025] Preferably, the slots are cut such that all the posts have the same length. The slots are preferably cut such that the back plate has a thickness smaller than the maximum cross-sectional dimension of the post transverse to its longitudinal axis.

[0026] Electrical discharge machining, particularly wire electric discharge machining or electrochemical machining, is preferred for cutting slots. These methods apply only a small force to the material being machined and are therefore particularly advantageous for machining discontinuous materials.

[0027] If the column comprises or is composed of layers of magnetic material sheets, such as laminated sheets, there is a risk that the sheets located next to the slots in the column may become very thin and thus burn completely under the heat generated by the electrical discharge machining (EDM). In the resulting motor, the motor parameters of the three motor phases may deviate due to the irregular burning of the column material. Therefore, according to the second aspect of this disclosure, which is separate from and accumulative of the first aspect, the orientation of the sheets within the column relative to the axis of rotation is the same for all columns. In this way, the risk of excessively thin sheets can be reduced or completely avoided. As an additional benefit, since the orientation of the sheets in the column is the same for all columns, the EDM affects all columns in substantially the same manner, and therefore the three motor phases in the resulting motor are affected in the same manner.

[0028] In a preferred embodiment of the second aspect, the monolith is configured such that sheets of magnetic material are arranged circularly around an axis of rotation, in a variation being in the form of at least one wound sheet. Once slots are cut into the monolith to form pillars, each of the resulting pillars has sheets of soft magnetic material arranged concentrically around the axis of rotation. Thus, the orientation of the sheets within the pillars relative to the axis of rotation is the same for all pillars.

[0029] In another preferred embodiment of the second aspect, the monolith comprises a plurality of triangular segments connected together like blocks of cake to form a substantially cylindrical monolith. Within each triangular segment, layers of soft material are arranged such that an intermediate layer between one or two of the sheets is arranged in a plane including the axis of rotation. Preferably, the triangular segments have symmetrical triangular cross-sections such that an intermediate layer between the central sheet or the two most central sheets of the triangular segment is arranged in a plane including the axis of rotation. Once a slot is cut in the monolith along the interface between adjacent triangular segments to form a column, each of the resulting columns has an intermediate layer between one or two of the sheets arranged in a plane including the axis of rotation. Similarly, the orientation of the sheets within the column relative to the axis of rotation is the same for all columns.

[0030] In another aspect of this disclosure, a method for manufacturing a blood pump is proposed. The blood pump includes a drive unit having a magnetic core, wherein the magnetic core is manufactured in the manner described above. Attached Figure Description

[0031] The foregoing summary of the invention and the following detailed description will be better understood when read in conjunction with the accompanying drawings. Reference has been made to the accompanying drawings for illustrative purposes. However, the scope of this disclosure is not limited to the specific embodiments disclosed in the drawings. In the drawings: Figure 1 A cross-sectional view of the blood pump is shown; Figure 2 A cross-sectional view of a preferred embodiment of the drive unit-impeller arrangement is shown; Figures 3A to 3C It shows the manufacture for according to Figure 2 The steps of the integrated magnetic core of the drive unit; Figures 4A to 4C It shows that according to Figures 3A to 3C Welds on the manufactured monolithic magnetic core; Figures 5A to 5J Cross-sections of the column are shown according to various embodiments; Figures 6A to 6B A single piece of concentric soft magnetic sheet is shown before and after the slots are cut therein; and Figures 7A to 7C The image shows a single block consisting of triangular blocks of layered soft magnetic sheets before and after the slots are cut into it. Detailed Implementation

[0032] refer to Figure 1 The diagram shows a cross-sectional view of the 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 known as a catheter pump, and is inserted into a patient's blood vessel via a catheter 25. The blood flow inlet 21 is located at the end of a flexible sheath 23, which can be placed through a heart valve, such as the aortic valve, during use. The blood flow outlet 22 is located on the side surface of the pump housing 2 and can be placed in a cardiovascular system, such as the aorta. The blood pump 1 is electrically connected to an electrical line 26 extending through the catheter 25 for supplying power to the blood pump 1 to drive it via a drive unit 4, as explained in more detail below.

[0033] If the blood pump 1 is intended for long-term use, i.e., in cases where it is implanted in a patient for weeks or even months, then power is preferably supplied by a battery. This allows the patient to be mobile, as they are not connected to a base station by cable. The battery can be carried by the patient and can supply power to the blood pump 1, for example, wirelessly.

[0034] Blood is delivered along a passage 24 connecting a blood flow inlet 21 and a blood flow outlet 22 (blood flow is indicated by arrows). An impeller 3 is provided for delivering blood along the passage 24 and is mounted so as to be rotatable within the pump housing 2 about a rotation axis 10 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 and 12 are contact bearings. However, at least one of bearings 11 and 12 can be a non-contact bearing, such as a magnetic or hydrodynamic bearing. The first bearing 11 is a pivot bearing having a spherical bearing surface that allows rotational and pivoting motion to a certain extent. A pin 15 is provided and forms one of the bearing surfaces. The second bearing 12 is disposed in a support member 13 to stabilize the rotation of the impeller 3, the support member 13 having at least one opening 14 for blood flow. Blades are disposed on the impeller 3 for delivering blood once the impeller 3 rotates. The rotation of the impeller 3 is caused by a drive unit 4 magnetically coupled to a magnet 32 ​​at the end portion of the impeller 3. The blood pump 1 shown in the diagram is a hybrid blood pump, in which the main direction of flow is axial. It should be understood that blood pump 1 can also be a pure axial flow blood pump, depending on the arrangement of the impeller 3, especially the blades 31.

[0035] The blood pump 1 includes an impeller 3 and a drive unit 4. The drive unit 4 includes multiple columns 40, for example, six columns 40, only two of which are in... Figure 1 As can be seen in the cross-sectional view. The columns 40 are arranged parallel to the axis of rotation 10; more specifically, the longitudinal axis of each of the columns 40 is parallel to the axis of rotation 10. One end of the column 42 is positioned adjacent to the impeller. Coil windings 44 are arranged around the column 40. The coil windings 44 are sequentially controlled by a controller to create a rotating magnetic field. Part of the control unit is a printed circuit board 6 connected to the wiring 26. The impeller has a magnet 32, which in this embodiment is formed as a multi-piece magnet. The magnet 32 ​​is disposed at the end of the impeller 3 facing the drive unit 4. The magnet 32 ​​is arranged to interact with the rotating magnetic field, thereby causing the impeller 3 to rotate about the axis of rotation 10.

[0036] To close the magnetic flux path, a backplate 50 is positioned at the end of the column 40 opposite to the impeller side of the column. The column 40 functions as a magnetic core and is made of a suitable material, particularly a soft magnetic material, such as steel or a suitable alloy, especially cobalt steel. Similarly, the backplate 50 is made of a suitable soft magnetic material, such as cobalt steel. The backplate 50 enhances the magnetic flux, which allows for a reduction in the overall diameter of the blood pump 1, which is important for intravascular blood pumps. For the same purpose, a yoke 37, i.e., another impeller backplate, is disposed in the impeller 3 on the side of the magnet 32 ​​facing away from the drive unit 4. In this embodiment, the yoke 37 has a conical shape to guide blood flow along the impeller 3. The yoke 37 can also be made of cobalt steel. One or more flushing channels extending toward the central bearing 11 can be formed in the yoke 37 or the magnet 32.

[0037] Figure 2 It shows the method for using according to Figure 1 A cross-sectional view of a preferred embodiment of the impeller arrangement of the blood pump drive unit. From Figure 2 As can be seen, the impeller-side end 420 of column 40 does not extend radially beyond winding 44. Instead, the cross-section of column 40 is constant in the direction of its longitudinal axis LA. This avoids columns 40 from approaching each other, as this could cause partial magnetic short circuits and thus reduce the power of the blood pump's motor.

[0038] according to Figure 2 The drive unit may include at least two, at least three, at least four, at least five, or preferably six pillars 40. A higher number of pillars 40, such as nine or twelve, is also possible. Only two pillars 40 are visible due to the cross-sectional view. The pillars 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.

[0039] The magnetic core 400 includes the drive unit 4 as a single magnetic component, namely, the post 40 and the back plate 50. The single component is composed of a discontinuous soft magnetic material, which is discontinuous in terms of conductivity. The discontinuous soft magnetic material comprises multiple sheets 85 made of ferromagnetic material and stacked on top of each other. The stacking direction is arranged in the direction of the longitudinal axis LA of the post 40 and is marked with an arrow DL. As shown, the post 40 is arranged parallel to the axis of rotation 10.

[0040] The coil winding 44 extends to the impeller-side end 420 of the column 40. This has the advantage that a magnetomotive force can be generated along the entire column 40. The magnetic core 400 includes a protrusion 401 located at the rear end 450 of the column 40, projecting radially relative to the column 40. The protrusion 401 can serve as a stop for the coil winding 44 towards the back plate 50. Due to the high rigidity of the integral magnetic core 400 between the back plate 50 and the column 40, the spacer located at the impeller-side end 420 of the column between the columns 40 can be omitted. The advantage provided by the integral magnetic core 400 is that optimal magnetic connection between the column 40 and the back plate 50 can be achieved. The magnetic core 400 can have a diameter of less than 10 mm.

[0041] Figures 3A to 3C The manufacturing process for, for example Figure 2 The steps of the magnetic core 400 of the drive unit 4 with impeller arrangement shown in the diagram. Figure 3A The perspective view shows a cubic block 9 forming the workpiece used to manufacture the magnetic core 400. The block 9 is composed of a discontinuous soft magnetic material with respect to electrical conductivity. It comprises sheets 85 oriented in a stacking direction DL, which extends along the principal plane of the sheets 85. Each sheet 85 is bonded to its adjacent sheet by a bonding layer of non-conductive material. Figures 3A to 3C It is not explicitly shown in the text.

[0042] Figure 3B The magnetic core 400 is shown in a semi-manufactured state, in which it has been machined from the cubic monolith 9, such as by turning, into a substantially cylindrical body 94. In this machining step, protrusions 401 are manufactured. The diameter-reduced section 404 of the outer peripheral surface of the pillar 40 forming the magnetic core 400 of the body 94 is manufactured to have a diameter corresponding to the outer radius of the outermost convex surface 842 of the pillar 40.

[0043] Then, the main body 94 was further manufactured to produce, for example... Figure 3C The magnetic core 400 is shown. For this manufacturing step, electrical discharge machining (EDM) can be used. Specifically, wire EDM can be applied to produce slots 49 that separate the posts 40 from each other. Inside the slots, space is provided for the coil windings 44. At the base of the slots 49, a central region 59 of an integral backplate 50 extends between the rear ends of the posts 40. The central region is integral with the posts 40 and with the backplate 50. Therefore, the entire magnetic core is formed from a single piece 9.

[0044] The stacking direction DL in the magnetic core 400 is parallel to the axis of rotation 10. It is permissible for the stacking direction DL in the substrate 50 to be non-parallel to the magnetic flow between the pillars 40 in the substrate 50. The magnetic core 400 can also be made of a wound soft magnetic sheet material separated by non-conductive layers. In this case, the stacking direction DL in the substrate 50 is always in the circumferential direction, which is advantageous for avoiding eddy currents in the magnetic flux within the substrate 50.

[0045] Figures 4A to 4C It is shown in accordance with Figures 3A to 3C One or more welds can be provided on the surface of the manufactured monolithic magnetic core. Accordingly, in the illustrated embodiment, three welds 82, 83 are provided on one side of the cubic monolith 9. The welds 82, 83 are spaced apart from each other and are welded through the cross-section of the body 94 to be cut from the monolith 9. The welds 82, 83 extend perpendicular to the stacking direction DL of the sheet 85. In this way, the sheets of discontinuous soft magnetic material are connected to each other. Instead of three welds, more welds or a single wide weld can be provided. Furthermore, similar welds can be provided on the opposite side of the monolith 9 (not shown). Instead of welds on the opposite side or except for welds on the opposite side, one or more welds can be provided on the side surface of the monolith 9 at the apex of the back plate 50 to completely or at least partially surround the back plate 50. The sheets 85 have a better mechanical connection to each other due to the welds 82, 83 and are also electrically connected. The latter has the advantage that current can flow from any location in the discontinuous soft magnetic material to every possible electrical connection location in the body 94 required for electrical discharge machining. This significantly simplifies the electrical discharge machining process. Furthermore, higher process reliability is achieved because the backplate-pillar units to be cut from the body 94 do not scatter due to delamination. Preferably, laser welding is applied. This can be advantageous for applying welding power twice or even more frequently to the same weld.

[0046] Figure 5A Figure 5 illustrates various embodiments of the column as seen in cross-section. Figures 5A to 5D An embodiment is shown in which the pillars are recessed, i.e., formed by a plurality of sheets 171 insulated from each other by an insulating layer 172. The insulating layer 172 may include an adhesive, varnish, baked enamel, or the like. Figure 5A and Figure 5B An embodiment in which the thickness of sheet 171 is uniform is shown. The thickness can range from 25 µm to 450 µm. Figure 5A The sheet 171 shown has a thickness that is greater than that in Figure 5B The sheet shown has a thickness of 171. Figure 5CThe sheets in the column have varying thicknesses, with the central sheet having the greatest thickness and the outermost sheet 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 the thinner sheets. Eddy currents in the central region are less critical, and the relatively thicker central sheet can help increase the magnetic flux. The orientation of sheet 171 can be consistent with that in... Figure 5D The differences shown are illustrative, provided that the soft magnetic material in the shown cross-section, i.e., the soft magnetic material in the cross-section transverse to the direction of magnetic flux, is discontinuous or discontinuous.

[0047] Figure 5E and Figure 5F An embodiment is shown in which the post 141 is formed by 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 this implementation, all lines have the same diameter, while Figure 5F In this implementation, the central line has the largest diameter and the outermost line has a smaller diameter, similar to... Figure 5C The embodiment shown is a sheet with varying thickness. (As in...) Figure 5G As shown, wires 181 with different diameters can be mixed, which can increase the total cross-sectional area of ​​the soft magnetic material compared to an embodiment in which all wires have the same diameter. Alternatively, to further minimize the insulating layer 184 between the wires 183, the wires 183 can have a polygonal cross-sectional area, such as rectangular, square, etc.

[0048] Alternatively, the discontinuous cross-section of column 141 can be as follows: Figure 5I The metal particles 185 embedded in the polymer matrix 186 can be shown, or created from steel wool or other porous structures impregnated with an insulating matrix. The porous and therefore discontinuous structure of the soft magnetic material can also be produced by sintering or high-pressure molding processes, in which the insulating matrix can be omitted because the insulating layer is automatically formed by the oxidation of the soft magnetic material through exposure to air. Alternatively, the pillar 141 can be formed from a rolled sheet 187 of soft magnetic material, wherein the layers of the rolled sheet 187 are separated by an insulating layer 188, as shown in... Figure 5J As shown. This provides a cross-section for reducing eddy current discontinuities in column 141 or column 40 in the sense of this disclosure.

[0049] If the column comprises or is composed of layers of magnetic material sheets, such as laminated sheets, there is a risk that the sheets located next to the slots in the column may become very thin and thus burn completely under the heat generated by electrical discharge machining or alternative manufacturing methods. As a result, due to the irregular burning of the column material, the motor parameters of the three motor phases in the resulting motor may deviate. Therefore, in Figure 6B and 7C In the two embodiments shown below, the orientation of the sheets within the columns relative to the axis of rotation is the same for all columns, and the orientation is chosen such that no sheet is oriented parallel to the slot. This prevents any sheet from becoming too thin and potentially burning out during cutting. Furthermore, since the orientation of the sheets within the columns relative to the axis of rotation is the same for all columns, the electrical discharge machining used to create the slots affects all columns in substantially the same way, and consequently, the three motor phases in the resulting motor are affected in the same way and therefore do not deviate from each other.

[0050] exist Figure 6A and Figure 6B In the embodiment shown, a single block 9 is first provided, in which sheets 85 of magnetic material are arranged concentrically around a rotation axis. Figure 6A In its variant, sheet 85 is arranged in the form of a wound sheet or multiple wound sheets. Then, as in Figure 6B As shown, slot 49 is cut in block 9 to form pillar 40. It can be seen that each pillar 40 has a sheet 85 of soft magnetic material arranged concentrically around the axis of rotation. Therefore, the orientation of the sheet 85 within pillar 40 relative to the axis of rotation is the same for all pillars.

[0051] exist Figures 7A to 7C In the embodiment shown, the single block 9 is composed of six triangular segments 9a. The triangular segments 9a can be cut from a stack of laminated sheets 85 of soft magnetic material, such as a stack of laminated steel sheets, and then joined together like blocks of a cake to form a shape as shown in the diagram. Figure 7A The single block 9 is shown in the figure. The triangular segments 9a have identical cross-sections, and each forms a triangle with sides of the same length. Therefore, the triangular cross-sections are symmetrical. It is worth noting that the triangular segments 9a are cut from a stack of layered sheets 85 such that the central sheet 85 or the intermediate layer between the two innermost sheets 85 forms a symmetrical triangular cross-section. Then, six triangular segments 9a are arranged in the single block 9 such that the central sheet 85 or the intermediate layer between the two innermost sheets 85 of each of the six triangular segments 9a is arranged in a plane including the axis of rotation.

[0052] Next, the single piece 9 was reshaped as follows.Figure 7B The shape shown is substantially cylindrical or substantially tubular. Finally, the slot 49 is cut in the monolith 9 along the interface 49a between adjacent triangular segments 9a to form as shown in Figure 7C The column 40 is shown in the figure. Therefore, each of the resulting columns 40 has an intermediate layer between one or two of its sheets 85 arranged in a plane including the axis of rotation. Similarly, the orientation of the sheets 85 within the column 40 relative to the axis of rotation is the same for all columns 40.

[0053] exist Figure 6B and 7C In one embodiment, the slot 49 does not extend axially through the monolith 9, but has a certain depth that defines the length of the post 40 and the thickness of the back plate 50 integral with the post 40. In an alternative embodiment, the slot 85 may extend through the monolith to isolate the post 40 from it. The isolated post 40 may be assembled into a motor with other components, such as the separate back plate 50.

Claims

1. A blood pump (1), comprising: The pump housing (2) has a blood flow inlet (21) and a blood flow outlet (22). Impeller (3), which is arranged in the pump housing (2) to be rotatable about a rotation axis (10), has blades (31) of a size and shape designed to transport 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) including a magnetic core (400), the magnetic core (400) including a plurality of columns (40) arranged around the axis of rotation (10) and a back plate (50) connecting the columns (40) and extending between the columns (40) in an intermediate region (59), and Coil windings (44) are arranged around each of the posts (40), and the coil windings (44) can be controlled to create a rotating magnetic field; The impeller (3) includes a magnetic structure (32) arranged to interact with the rotating magnetic field to cause the impeller (3) to rotate. The magnetic core (400) comprises a layered sheet (85) of soft magnetic material or is composed of a layered sheet (85) of soft magnetic material, such that the soft magnetic material is discontinuous in conductivity in a cross-section transverse to the laminated layered sheet. The material of the column (40) is integral with the material of the intermediate region (59) of the back plate (50) located between the columns (40), and the orientation of the sheet (85) within the column (40) relative to the axis of rotation (10) is the same for all columns (40). Within each of the pillars (40), an intermediate layer between one of the sheets (85) of soft magnetic material or between two of the sheets (85) of soft magnetic material is arranged in a plane including the axis of rotation (10).

2. The blood pump (1) according to claim 1, comprising at least one weld (82, 83, 86) bridging the discontinuity in conductivity of the soft magnetic material.

3. The blood pump (1) according to claim 2, wherein at least one of the at least one welded portion (82, 83, 86) is arranged on the surface of the back plate (50) opposite to the column (40).

4. The blood pump (1) according to claim 2 or 3, wherein at least one of the at least one welded portion is arranged on the end surface of the column (40) opposite to the back plate (50).

5. A method for manufacturing a magnetic core (400) for a drive unit (4) of a blood pump (1), the magnetic core having a rotation axis (10) and including a plurality of posts (40) arranged around the rotation axis (10) and a back plate (50) connecting the posts (40), the method comprising the following steps: Provide a single block (9) comprising or composed of a layered sheet (85) of soft magnetic material such that the soft magnetic material is discontinuous in conductivity in a cross section transverse to the laminated sheet; as well as The slot is cut into the single piece (9) to create the column (40) and the back plate (50) such that the column (40) is arranged about the axis of rotation (10), wherein the orientation of the sheet (85) within the column (40) relative to the axis of rotation (10) is the same for all columns (40), such that the back plate (50) forms an integral component with the column (40), wherein the slot is cut such that an intermediate layer between one or two sheets (85) of soft magnetic material in each of the columns (40) is arranged in a plane including the axis of rotation (10).

6. The method according to claim 5, wherein the slot (49) is cut by electrical discharge machining.

7. The method of claim 6, wherein the slot is cut by electrical discharge machining using wire cutting.

8. The method of claim 5, wherein the slot is cut by electrochemical machining.

9. A method of manufacturing a blood pump (1) having a drive unit (4) with a magnetic core (400), wherein the magnetic core (400) is manufactured according to any one of claims 5 to 8.

10. A blood pump (1), comprising: The pump housing (2) has a blood flow inlet (21) and a blood flow outlet (22). Impeller (3), which is arranged in the pump housing (2) to be rotatable about a rotation axis (10), has blades (31) of a size and shape designed to transport 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) including a magnetic core (400), the magnetic core (400) including a plurality of columns (40) arranged around the axis of rotation (10) and a back plate (50) connecting the columns (40) and extending between the columns (40) in an intermediate region (59), and Coil windings (44) are arranged around each of the posts (40), and the coil windings (44) can be controlled to create a rotating magnetic field; The impeller (3) includes a magnetic structure (32) arranged to interact with the rotating magnetic field to cause the impeller (3) to rotate. The magnetic core (400) comprises a layered sheet (85) of soft magnetic material or is composed of a layered sheet (85) of soft magnetic material, such that the soft magnetic material is discontinuous in conductivity in a cross-section transverse to the laminated layered sheet. The material of the column (40) is integral with the material of the intermediate region (59) of the back plate (50) located between the columns (40), and the orientation of the sheet (85) within the column (40) relative to the axis of rotation (10) is the same for all columns (40). Within each of the columns, the sheets of soft magnetic material are arranged concentrically around the axis of rotation.

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