Blood pump

Abstract

To improve the magnetic flux in a magnetic core.SOLUTION: A blood pump (1) comprises: a pump casing (2) with a blood flow inlet (21) and a blood flow outlet (22); and an impeller (3) arranged within the pump casing (2) so as to be rotatable about an axis of rotation (10). The impeller (3) has blades (31) sized and shaped for conveying blood. The blood pump (1) comprises a drive unit (4) for rotating the impeller (3). The drive unit (4) comprises: a magnetic core (400) including a plurality of posts (40) arranged about the axis of rotation (10); and a back plate (50) connecting the posts (40) and extending between the posts (40) in an intermediate area (59). A coil winding (44) is disposed around each of the posts (40). A material of at least a portion of at least one of the posts (40) is integral with a material of the intermediate area (59) of the back plate (50).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a blood pump, and more particularly to an intravascular blood pump for percutaneous insertion into a patient's blood vessel to support blood flow within the patient's blood vessel, the blood pump having an improved drive unit. [Background technology]

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

[0003] Blood pumps are typically driven by a drive unit, which may be an electric motor. For example, U.S. Patent No. 5,629,999 discloses an extracorporeal blood pump having an impeller that can be magnetically coupled to an electric motor. The impeller includes a magnet disposed adjacent to a magnet in the electric motor. Rotation of the motor is transmitted to the impeller through attractive forces between the magnet in the impeller and the magnet in the motor. To reduce the number of rotating parts, U.S. Patent No. 5,629,999 discloses the use of a rotating magnetic field. The drive unit includes a plurality of stationary struts arranged around a rotation axis, each strut carrying a wire coil winding and acting as a magnetic core. A control unit continuously supplies voltage to the coil winding to generate the rotating magnetic field. To provide a sufficiently strong magnetic coupling, the magnetic force must be sufficiently high. This can be achieved by supplying a sufficiently high current to the drive unit or by providing a large magnet, but this results in a large overall diameter for the blood pump.

[0004] Patent document 2 discloses a blood pump, in particular an intravascular blood pump with magnetic coupling between a drive unit and an impeller, which has a compact design and in particular a high ratio of pumping power to pump size, resulting in sufficiently small overall dimensions that allow the blood pump to be inserted into a blood vessel transvascularly, transvenously, percutaneously or transvalvularly, or even smaller for reasons of handling and convenience.

[0005] More specifically, the blood pump of Patent Document 2 includes a pump casing having a blood inlet and a blood outlet, an impeller, and a drive unit for rotating the impeller. Rotation of the impeller around a rotation axis and within the pump casing allows blood to be transported from the blood inlet to the blood outlet by the impeller blades. The drive unit includes a magnetic core including a plurality of struts, preferably six, and a back plate connecting the rear ends of the struts and acting as a yoke. When viewed in a plane perpendicular to the rotation axis, the struts are arranged in a circle around the rotation axis, and each strut preferably has a longitudinal axis parallel to the rotation axis. The back plate has through openings within which the rear ends of the struts are received in a form-fitting manner such that the end face of the rear end of each strut is flush with the rear face of the back plate. In this way, a magnetic connection between the struts and the back plate is created between the periphery of the struts and the inner contour of the back plate opening. Each strut has a coil winding disposed therearound, which may be controlled in a coherent manner to generate a rotating magnetic field for driving an impeller, which includes a magnetic structure in the form of magnets arranged to interact with the rotating magnetic field to cause the impeller to follow its rotation. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] US Patent Application Publication No. 2011 / 0238172 [Patent Document 2] European Patent No. 3222301 Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to improve the magnetic flux within the magnetic core. [Means for solving the problem]

[0008] The blood pump of the present disclosure corresponds to the blood pump described above. It may therefore be an axial or diagonal blood pump, which pumps partly axially and partly radially (the diameter of a purely centrifugal blood pump is usually too large for intravascular applications). However, according to one aspect of the present disclosure, the material of at least a portion of at least one strut of the magnetic core is integral with the material of the intermediate region of the back plate of the magnetic core, which is the region of the back plate located between the struts. Preferably, all struts are integrally connected to the back plate in this manner. In other words, at least one strut and the back plate, 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 reluctance at the transition between the struts and the back plate is minimized, thereby improving magnetic flux. Furthermore, good mechanical stiffness of the transition between the struts and the back plate can be achieved.

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

[0010] "Discontinuous" in the sense of this document means that the soft magnetic material, as seen in any cross section, for example transverse to the longitudinal axis of the strut, is interrupted, separated, crossed, etc. by insulating or other material or gaps, thereby forming strictly separate regions of soft magnetic material or regions that are interrupted but connected in different places.

[0011] Providing discontinuous soft magnetic material in cross sections transverse to the direction of magnetic flux reduces eddy currents, thereby reducing heat generation and energy consumption as described above. The total amount of soft magnetic material is maximized while minimizing continuous areas of soft magnetic material to substantially not weaken the magnetic field compared to continuous or entire body (i.e., solid) soft magnetic material. This can be achieved, for example, by providing the soft magnetic material in the form of multiple sheets of soft magnetic material, such as magnetic steel sheets. In particular, the sheets may be stacked, e.g., laminated, to form a stack of sheets. The sheets are preferably electrically insulated from each other, for example, by providing an adhesive, lacquer, baked enamel, or the like, between adjacent ones of the sheets. Such a configuration can be referred to as "grooved." Compared to the entire soft magnetic material, the amount of soft magnetic material is only slightly reduced and the amount of insulating material is kept small, so that the magnetic field resulting from a grooved post is substantially the same as that resulting from a solid post. In other words, heat generation and energy consumption can be significantly reduced, and only a small amount of magnetic field is lost due to the insulating material.

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

[0013] In particular, regions of a particular type of material, such as a sheet of soft magnetic material, may extend through both the posts and the backplate. The material is discontinuous, but the magnetic core may be made from a single block of such material. The extension of such regions of a particular type of material is not interrupted by the transition between the posts and the backplate, but is integrally continuous from the posts to the intermediate regions of the backplate located between the posts.

[0014] It is commonly known to avoid or reduce eddy currents by providing electric motors with grooved soft magnetic materials, such as electromagnetic steel. However, this technique has been applied to large devices, where the sheets typically have thicknesses in the range of about 500 μm or greater. In small applications, such as the blood pump of the present disclosure, where one of the struts typically has a diameter on the order of magnitude and the power input is relatively low (e.g., up to 20 watts (W)), eddy currents and related problems were not anticipated. Surprisingly, despite the small diameter of the strut, eddy currents, and therefore heat generation and energy consumption, can be reduced by providing grooved struts. This is advantageous for the operation of blood pumps, which can be operated at high speeds of up to 50,000 rpm (revolutions per minute).

[0015] It will be appreciated that other arrangements than the grooved arrangement described above may be possible for providing discontinuous soft magnetic material within the struts. For example, instead of a plurality of sheets, a plurality of wires, fibers, struts, or other elongated elements may be provided to form each of the struts of the drive unit. The wires may be provided in the form of a bundle of wires, in which the wires are electrically insulated from one another, for example, by a coating surrounding each wire or an insulating matrix in which the wires are embedded, and may have various cross-sectional shapes, such as annular, circular, rectangular, square, or polygonal. Similarly, particles of soft magnetic material, wire wool of soft magnetic material, or another spongy or porous structure may be provided, in which case the spaces between the regions of soft magnetic material contain an electrically insulating material, such as an adhesive, lacquer, or polymer matrix. Porous and discontinuous structures of soft magnetic material may also be formed by sintering or pressing materials. In such structures, an additional insulating material may be omitted, since the insulating layer may automatically form due to the oxide layer resulting from oxidation of the soft magnetic material upon exposure to air.

[0016] Sheets or other structures of soft magnetic material may be uniformly formed, i.e., the sheets within one of multiple or all struts may have the same thickness or the wires may have the same diameter, or a non-uniform arrangement may be provided. For example, the sheets may have varying thicknesses or the wires may have varying diameters. More specifically, particularly with respect to a stack of sheets, one or more central sheets may have a larger thickness, while adjacent sheets toward the ends of the stack may have a smaller thickness, i.e., the thickness of the sheets decreases from the center to the ends of the stack, i.e., toward the outermost sheets of the stack. Similarly, one or more central wires in a bundle of wires may have a larger diameter, while the wires at the ends of the struts may have a smaller diameter, i.e., the diameter of the wires may decrease from the center to the ends of the bundle, i.e., toward the outermost wires of the bundle. It may be advantageous to provide a larger continuous region of soft magnetic material in the center of the strut with respect to a cross section transverse to its longitudinal axis, i.e. a relatively thick sheet or wire in the center, because this may enhance the magnetic flux passing through the center along the longitudinal axis of each strut, and the eddy currents in the center will be smaller than the eddy currents at the sides of the strut. In other words, such a configuration may be advantageous because eddy currents in the side regions of the strut are more significant and can be reduced by a thinner sheet or wire in the side regions.

[0017] The diameter of the backplate 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 backplate 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 array of struts may be in the range of 3 mm to 8 mm, such as 4 mm to 7.5 mm, preferably 6.5 mm.

[0018] As mentioned above, the support pole is made of a soft magnetic material such as electromagnetic steel (magnetic steel). The support pole and back plate may be made of the same material. Preferably, the drive unit, including the support pole and back plate, is made of cobalt steel. The use of cobalt steel contributes to reducing the pump size, especially the diameter. Of all the electromagnetic steels, cobalt steel generates the greatest magnetic flux for the same amount of material used, due to its highest permeability and highest saturation flux density.

[0019] The dimensions of the struts, particularly their length and cross-sectional area, can vary based on and depend on various factors. In contrast to the dimensions of the blood pump, e.g., its outer diameter, which depends on the application of the blood pump, the dimensions of the struts are determined by the electromagnetic properties that are tailored to achieve the desired performance of the drive unit. One of the factors is the magnetic flux density that must be achieved with the minimum cross-sectional area of ​​the struts. The smaller the cross-sectional area, the higher the current required to achieve the desired magnetic flux. However, higher currents generate more heat in the coil wire due to electrical resistance. That is, "thin" struts are preferred for reducing the overall size, but this requires a higher current, which results in undesirable heat. The heat generated in the wire also depends on the length and diameter of the wire used for the coil winding. A short wire length and a large wire diameter are preferred to minimize winding losses (also called "copper losses" or "copper power losses" when copper wire is commonly used). In other words, a smaller wire diameter generates more heat compared to a thicker wire at the same current, and a preferred wire diameter is 0.05 mm to 0.2 mm, e.g., 0.1 mm. Further factors affecting the strut size and performance of a drive unit are the number of coil turns and the outer diameter of the windings, i.e., the strut containing the windings. Multiple windings may be arranged in more than one layer around each strut, e.g., two or three layers may be provided. However, the more layers, the more heat is generated due to the longer length of wire in the outer layer with the larger winding diameter. Increased wire length may generate more heat due to the higher resistance of long wire compared to shorter wire. Therefore, a single layer of windings with a small winding diameter may be preferred. A typical number of windings, which in turn depends on the strut length, may be about 50 to about 150, e.g., 56 or 132. Regardless 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 it has an electrical resistivity that is about 5% less than that of copper.

[0020] Preferably, the magnetic core includes one or more welds. The welds may be arranged on an outer surface of the magnetic core, which outer surface is particularly accessible for, for example, laser welding. The welds bridge electrical conductivity discontinuities in the soft magnetic material, thus electrically connecting at least two sheets of soft magnetic material. The welds also add mechanical stability to the discontinuous soft magnetic material.

[0021] One or more welds may be arranged on the surface of the backplate opposite the support posts. They may be created by laser welding. When laminated sheets are used, the welds preferably bridge adjacent soft magnetic sheets diagonally or laterally.

[0022] In a further aspect of the present disclosure, a method for manufacturing a magnetic core for a drive unit of an intravascular blood pump is proposed. The magnetic core has an axis of rotation and includes a plurality of struts arranged about the axis of rotation and a backplate connecting the struts. The method includes the steps of providing a monoblock of magnetically conductive material and cutting grooves in the monoblock to produce both the struts arranged about the axis of rotation and the backplate forming an integral part of the struts. As noted above, an advantage of such manufacturing is the production of a magnetic core with reduced reluctance.

[0023] At least one groove, preferably all grooves on opposite sides of the rotation axis, can be produced by cutting through the rotation axis of the magnetic core, so that a uniform distribution of the struts around the rotation axis can be easily achieved.

[0024] Preferably, the grooves are cut so that the posts all have the same length. The grooves are particularly cut so that the backplate has a thickness that is less than the maximum cross-sectional dimension of the posts transverse to their longitudinal axes.

[0025] It is preferred to cut the grooves using electrical discharge machining, especially wire electrical discharge machining, or electrochemical machining, as these methods apply only small forces to the material to be machined and are therefore particularly advantageous for machining discontinuous materials.

[0026] If the struts include or are made of laminated sheets of magnetic material, such as laminated sheets, the sheets in the struts next to the grooves may become very thin and therefore burn out completely under the heat generated by the EDM. In the resulting motor, three motor phases may deviate from motor parameters due to irregular burning of the strut material. Therefore, according to a second aspect of the present disclosure, which is distinct from the first aspect of the present disclosure and may be cumulative, the orientation of the sheets within the struts relative to the rotation axis is the same for all struts. In this way, the risk of the sheets being too thin can be reduced or completely avoided. As a side effect, because the orientation of the sheets within the struts is the same for all struts, the EDM affects all struts in substantially the same manner, and all three motor phases in the resulting motor are similarly affected in the same manner.

[0027] In one preferred embodiment of this second aspect, the monoblock comprises sheets of magnetic material, in one variant in the form of at least one coiled sheet, arranged in a circle around the axis of rotation. When grooves are cut in the monoblock to form the posts, each resulting post has a sheet of soft magnetic material arranged in a concentric circle around the axis of rotation. Thus, the orientation of the sheets within the posts relative to the axis of rotation is the same for all posts.

[0028] In another preferred embodiment of this second aspect, the monoblock is composed of several triangular sections connected together like cake pieces to form a substantially cylindrical monoblock. Within each triangular section, laminated sheets of flexible material are arranged such that one of the sheets or an intermediate layer between two of the sheets is aligned in a plane containing the axis of rotation. Preferably, the triangular sections have a symmetrical triangular cross section, with the intermediate layer or central sheet between the two middle sheets of the triangular section aligned in a plane containing the axis of rotation. When grooves are cut in the monoblock along the interfaces between adjacent triangular sections to form posts, each resulting post has one of the sheets or one of the intermediate layers between two of the sheets aligned in a plane containing the axis of rotation. Again, the orientation of the sheets within the posts relative to the axis of rotation is the same for all posts.

[0029] In a further aspect of the present disclosure, a method for manufacturing a blood pump is proposed, the blood pump comprising a drive unit having a magnetic core, the magnetic core being manufactured in the manner described above.

[0030] The foregoing summary and the following detailed description of the preferred embodiments will be better understood when read in conjunction with the accompanying drawings. For purposes of explaining the present disclosure, reference is made to the drawings. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the following drawings. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a cross-sectional view of a blood pump. [Figure 2] FIG. 1 is a cross-sectional view of a preferred embodiment of a drive unit-impeller arrangement. [Figure 3A] 3A to 3C show steps for manufacturing an integrated magnetic core for the drive unit according to FIG. 2. [Figure 3B] 3A to 3C show steps for manufacturing an integrated magnetic core for the drive unit according to FIG. 2. [Figure 3C]3A to 3C show steps for manufacturing an integrated magnetic core for the drive unit according to FIG. 2. [Figure 4A] 3A-3C show welds on a one-piece magnetic core as manufactured according to FIGS. [Figure 4B] 3A-3C show welds on a one-piece magnetic core as manufactured according to FIGS. [Figure 4C] 3A-3C show welds on a one-piece magnetic core as manufactured according to FIGS. [Figure 5A] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 5B] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 5C] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 5D] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 5E] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 5F] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 5G] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 5H] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 5I] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 5J] 10A-10C illustrate cross sections through struts according to various embodiments. [Figure 6A] FIG. 1 shows a monoblock of concentric soft magnetic sheets before grooves are cut. [Figure 6B] FIG. 10 shows a monoblock of concentric soft magnetic sheets after grooves have been cut. [Figure 7A] 1 shows a monoblock consisting of a triangular block of laminated soft magnetic sheets before and after grooves are cut. FIG. [Figure 7B]1 shows a monoblock consisting of a triangular block of laminated soft magnetic sheets before and after grooves are cut. FIG. [Figure 7C] 1 shows a monoblock consisting of a triangular block of laminated soft magnetic sheets before and after grooves are cut. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0032] Referring to FIG. 1, a cross-sectional view of a blood pump 1 is shown. The blood pump 1 comprises a pump casing 2 having a blood inlet 21 and a blood outlet 22. The blood pump 1 is designed as an intravascular pump, also known as a catheter pump, and is deployed within a patient's blood vessels via a catheter 25. The blood inlet 21 is at the end of a flexible cannula 23, which may be placed through a heart valve, such as the aortic valve, during use. The blood outlet 22 is located within the side of the pump casing 2 and may be placed within a cardiac vessel, such as the aorta. The blood pump 1 is driven by a drive unit 4, which is electrically connected to an electrical line 26 extending through the catheter 25 to provide power to the blood pump 1, as described in more detail below.

[0033] If the blood pump 1 is intended for long-term use, i.e., when the blood pump 1 is intended to be used in a situation where it is implanted in a patient for weeks or even months, power is preferably provided by a battery. This allows the patient to be mobile, as they are not connected to a base station by a cable. The battery may be carried by the patient and may, for example, wirelessly provide electrical energy to the blood pump 1.

[0034] Blood is transported along a passage 24 (blood flow indicated by an arrow) connecting the blood inlet 21 and the blood outlet 22. An impeller 3 is provided to transport blood along the passage 24 and is rotatably mounted within the pump casing 2 by a first bearing 11 and a second bearing 12 around a rotation axis 10. The rotation axis 10 is preferably the longitudinal axis of the impeller 3. In this embodiment, both bearings 11 and 12 are contact-type bearings. However, at least one of the bearings 11 and 12 may be a non-contact bearing, such as a magnetic or hydrodynamic bearing. The first bearing 11 is a pivot bearing with a spherical bearing surface that allows rotational and pivotal movement to some extent. A pin 15 is provided and forms one of the bearing surfaces. The second bearing 12 is disposed within 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 and transport blood as the impeller 3 rotates. Rotation of the impeller 3 is caused by a drive unit 4 that is magnetically coupled to magnets 32 at the end portions of the impeller 3. The illustrated blood pump 1 is a mixed type blood pump in which the main direction of flow is axial. It will be understood that depending on the arrangement of the impeller 3, and in particular the blades 31, the blood pump 1 can be a purely axial blood pump.

[0035] Blood pump 1 includes impeller 3 and drive unit 4. Drive unit 4 includes a plurality of struts 40, such as six struts 40, only two of which are visible in the cross-sectional view of FIG. 1 . The struts 40 are arranged parallel to axis of rotation 10; more specifically, the longitudinal axis of each strut 40 is parallel to axis of rotation 10. One end of strut 42 is arranged adjacent to the impeller. Coil windings 44 are arranged around struts 40. The coil windings 44 are continuously controlled by a control that generates a rotating magnetic field. Part of the control unit is a printed circuit board 6 connected to electrical line 26. The impeller includes magnet 32, which in this embodiment is formed as a multi-piece magnet. Magnet 32 ​​is disposed at the end of impeller 3 facing drive unit 4. Magnet 32 ​​is disposed to interact with the rotating magnetic field to cause rotation of impeller 3 about axis of rotation 10.

[0036] To close the magnetic flux path, a backplate 50 is located at the end of the support 40 opposite the impeller side. The support 40 acts 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 strengthens 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 backplate, is provided within the impeller 3 on the side of the magnet 32 ​​facing away from the drive unit 4. In this embodiment, the yoke 37 has a conical shape to guide blood flow along the impeller 3. The yoke 37 may also be made of cobalt steel. One or more irrigation channels extending toward the central bearing 11 may be formed in the yoke 37 or the magnet 32.

[0037] Figure 2 is a cross-sectional view of a preferred embodiment of a drive unit-impeller arrangement for a blood pump according to Figure 1. As can be seen in Figure 2, the impeller ends 420 of the struts 40 do not extend radially above the windings 44. Rather, the cross-section of the struts 40 is constant in the direction of the longitudinal axis LA of the struts 40. Thus, struts 40 are avoided from being too close to each other, which would cause a partial magnetic short circuit, with the result of a power reduction in the electric motor of the blood pump.

[0038] 2 may comprise at least two, at least three, at least four, at least five, and preferably six, support posts 40. A greater number of support posts 40, such as nine or twelve, may be possible. Due to the cross-sectional view, only two support posts 40 are visible. The support posts 40 and backplate 50 form a magnetic core 400 of the drive unit 4, which may have a diameter of less than 10 mm.

[0039] The magnetic core 400 comprises the magnetic components of the drive unit 4, namely the posts 40 and the back plate 50, as a single piece or monoblock. The monoblock is constructed from discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity. The discontinuous soft magnetic material comprises a plurality of sheets 85 made from a ferromagnetic material that are laminated together. The lamination direction is aligned in the direction of the longitudinal axis LA of the posts 40 and is indicated by the arrow DL. As shown, the posts 40 are aligned parallel to the axis of rotation 10.

[0040] The coil windings 44 extend to the impeller-side end 420 of the support pillar 40. This has the advantage that a magnetic motive force can be generated along the entire support pillar 40. The magnetic core 400 has a protrusion 401 at the rear end 450 of the support pillar 40 that protrudes radially relative to the support pillar 40. This protrusion 401 can serve as a stop for the coil windings 44 toward the back plate 50. The one-piece magnetic core 400 provides high rigidity between the back plate 50 and the support pillar 40, so that spacers between the support pillars 40 at the impeller-side end 420 of the support pillars can be omitted. The one-piece magnetic core 400 offers the advantage that an optimal magnetic connection between the support pillar 40 and the back plate 50 can be achieved. The magnetic core 400 may have a diameter of less than 10 mm.

[0041] 3A-3C illustrate steps in fabricating a magnetic core 400 for a drive unit 4 of a drive unit-impeller arrangement such as that shown in FIG. 2. FIG. 3A is a perspective view of a cube-shaped monoblock 9 that forms the workpiece for fabricating the magnetic core 400. The monoblock 9 is made of a discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity. It comprises sheets 85 oriented in a lamination direction DL that extends along the major planes of the sheets 85. The sheets 85 are each bonded to each adjacent sheet by an adhesive layer of a non-conductive material not explicitly shown in FIGS. 3A-3C.

[0042] 3B shows the magnetic core 400 in a semi-manufactured state, in which it is machined, for example, to transform it from a cubic monoblock 9 into a substantially cylindrical body 94. In this machining step, protrusions 401 are produced. Smaller diameter portions 404 of the body 94, which form the periphery of the posts 40 of the magnetic core 400, are produced with a diameter corresponding to the outer radius of the outermost convex side 842 of the posts 40.

[0043] 3C, the body 94 may then be further manufactured to create the magnetic core 400. For this manufacturing step, electrical discharge machining may be used. In particular, wire-cut electrical discharge machining may be applied to create grooves 49 that separate the posts 40 from one another. Inside the grooves, space is provided for the coil windings 44. At the base of the grooves 49, an intermediate region 59 of the integral back plate 50 extends between the rear ends of the posts 40. The intermediate region is integral with the posts 40 and with the back plate 50. In this way, the entire magnetic core 400 is formed by a monoblock 9.

[0044] The lamination direction DL in the magnetic core 400 is intended to be parallel to the axis of rotation 10. It is permissible that the lamination direction DL in the base plate 50 is not parallel to the magnetic flow between the posts 40 in the base plate 50. It is also possible to manufacture the magnetic core 400 from coiled soft magnetic sheet material separated by non-conductive layers. Thus, the lamination direction DL in the base plate 50 is always circumferential, which is advantageous to avoid eddy currents in the magnetic flux in the base plate 50.

[0045] 4A-4C show how one or more welds can be provided on the surface of a one-piece magnetic core manufactured according to FIGS. 3A-3C. Thus, in the illustrated embodiment, three weld seams 82, 83 are provided on one side of the cubic monoblock 9. The weld seams 82, 83 are welded at a distance from one another across the cross section of the body 94 to be cut from the monoblock 9. The weld seams 82, 83 extend perpendicular to the lamination direction DL of the sheet 85. In this way, discontinuous sheets of soft magnetic material are connected. Instead of three weld seams, more weld seams or a single wide weld may be provided. In addition, a similar weld seam may be provided on the opposite side of the monoblock 9 (not shown). Alternatively or additionally to the welds on the opposite side, one or more weld seams may be provided on the side of the monoblock 9 at the level of the back plate 50, completely or at least partially surrounding the back plate 50. The sheets 85 have a better mechanical connection with each other by the weld seams 82, 83 and are also electrically connected. The latter has the advantage that current can flow from any position in the discontinuous soft-magnetic material to the respective position of the electrical connection in the body 94, which may be required for, for example, electrical discharge machining. This greatly facilitates electrical discharge machining. Furthermore, a higher process reliability is achieved, since the backplate-support unit, which should be cut out from the body part 94, cannot fall off due to delamination. Preferably, laser welding is applied. It may be advantageous to apply welding power to the same weld twice or even more times.

[0046] Figures 5A-5J show various embodiments of a support pillar viewed in cross section. Figures 5A-5D show embodiments in which the support pillar is grooved, i.e., formed from multiple sheets 171 insulated from one another by insulating layers 172. The insulating layers 172 may include adhesive, lacquer, baked enamel, etc. Figures 5A and 5B show embodiments in which the sheets 171 are uniform in thickness. The thickness may range from 25 μm to 450 μm. The sheet 171 shown in Figure 5A has a greater thickness than the sheet 171 shown in Figure 5B. The sheets shown in Figure 5C have varying thicknesses, with the central sheet having the greatest thickness and the outermost sheets having the least thickness. This can be advantageous because eddy currents in the side regions of the support pillar are more significant and can be reduced by thinner sheets. Eddy currents in the central region are less significant, and a relatively thick central sheet can help improve magnetic flux. The orientation of the sheet 171 may be different, as exemplarily shown in FIG. 5D, as long as the soft magnetic material in the cross section shown, i.e., the soft magnetic material in the cross section transverse to the direction of the magnetic flux, is discontinuous or interrupted.

[0047] 5E and 5F show embodiments in which the strut 141 is formed by a bundle of wires 181 insulated from one another by 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. In the embodiment of FIG. 5E, all of the wires have the same diameter, whereas in the embodiment of FIG. 5F, the central wire has the largest diameter and the outer wires have smaller diameters, similar to the embodiment shown in FIG. 5C, which has sheets with varying thicknesses. As shown in FIG. 5G, wires 181 of different diameters may be mixed, which may increase the total cross-sectional area of ​​the soft magnetic material compared to an embodiment in which all wires have the same diameter. Alternatively, the wires 183 may have polygonal cross-sectional areas, such as rectangular or square, to further minimize the insulating layer 184 between the wires 183.

[0048] Alternatively, the discontinuous cross-section of the strut 141 may be created by metal particles 185 embedded in a polymer matrix 186, as shown in FIG. 5I, or by steel wool or another porous structure impregnated with an insulating matrix. Porous, and therefore discontinuous, structures of soft magnetic material may also be manufactured by sintering or high-pressure molding processes, in which the insulating matrix may be omitted because the insulating layer is automatically formed by oxidation of the soft magnetic material upon exposure to air. As a further alternative, the strut 141 may be formed from a wound sheet 187 of soft magnetic material, with layers of the wound sheet 187 separated by insulating layers 188, as shown in FIG. 5J. This also provides a discontinuous cross-section within the strut 141 or strut 40 that reduces eddy currents within the strut 141 or strut 40 as meant by the present disclosure.

[0049] If the support pillars include or are made of laminated sheets of magnetic material, such as laminated sheets, the sheets in the support pillars next to the grooves may become very thin and burn out completely under the heat generated by the EDM or alternative manufacturing method. As a result, the motor parameters of the three motor phases in the resulting motor may deviate due to irregular burning of the support pillar material. Therefore, in the following two embodiments shown in FIGS. 6B and 7C , the orientation of the sheets in the support pillars relative to the rotation axis is the same for all support pillars, and the orientation is selected so that none of the sheets are oriented parallel to the grooves. In this way, none of the sheets may become very thin and burn out during the cutting process. Also, because the orientation of the sheets in the support pillars relative to the rotation axis is the same for all support pillars, the EDM process to form the grooves affects all support pillars in substantially the same way, and the three motor phases in the resulting motor are all similarly affected in the same way and do not deviate from each other.

[0050] In the embodiment shown in Figures 6A and 6B, first, a monoblock 9 is provided with sheets 85 of magnetic material arranged concentrically around the axis of rotation (Figure 6A). In a variant, the sheets 85 are provided in the form of a coiled sheet or multiple coiled sheets. Next, as shown in Figure 6B, grooves 49 are cut in the monoblock 9 to form the posts 40. As can be seen, each post 40 has a sheet 85 of soft magnetic material arranged concentrically around the axis of rotation. Thus, the orientation of the sheets 85 in the posts 40 relative to the axis of rotation is the same for all posts.

[0051] In the embodiment shown in FIGS. 7A-7C, the monoblock 9 is comprised of six triangular portions 9a. The triangular portions 9a may be cut out from a stack of laminated sheets 85 of soft magnetic material, such as a stack of laminated steel sheets, and then connected together like pieces of a cake to form the monoblock 9 shown in FIG. 7A. The cross sections of the triangular portions 9a are identical, each forming a triangle with sides of equal length. Thus, the cross section of the triangle is symmetrical. In particular, the triangular portions 9a are cut out from the stack of laminated sheets 85 such that either the central sheet 85 or the intermediate layer between the two centralmost sheets 85 forms the height of the symmetrical triangular cross section. The six triangular portions 9a are then arranged within the monoblock 9 such that the central sheet 85 or the intermediate layer between the two centralmost sheets 85 of each of the six triangular portions 9a is aligned in a plane containing the axis of rotation.

[0052] The monoblock 9 is then shaped into a substantially cylindrical or tubular shape, as shown in Figure 7B. Finally, grooves 49 are cut into the monoblock 9 along the interfaces 49a between adjacent ones of the triangular portions 9a to form the posts 40, as shown in Figure 7C. Each of the resulting posts 40 thus has one of its sheets 85, or an intermediate layer between two of the sheets 85, respectively, aligned in a plane containing the axis of rotation. Again, the orientation of the sheets 85 within a post 40 relative to the axis of rotation is the same for all posts 40.

[0053] 6B and 7C, the grooves 49 do not extend axially through the entire monoblock 9, but have a specific depth that defines the length of the struts 40 and the thickness of the backplate 50 that is integral with the struts 40. In an alternative embodiment, the grooves 85 may extend through the entire monoblock, thereby isolating the struts 40 from the monoblock. The isolated struts 40 may be assembled to a motor with another component, such as a separate backplate 50.

Claims

1. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump casing (2) having a blood inlet (21) and a blood outlet (22); an impeller (3) arranged within the pump casing (2) and rotatable about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to transport blood from the blood inlet (21) to the blood outlet (22); a drive unit (4) for rotating the impeller (3), the drive unit (4) comprising a magnetic core (400) including a plurality of struts (40) arranged around the rotation axis (10) and a back plate (50) connecting the struts (40) and extending between the struts (40) in an intermediate region (59); a coil winding (44) disposed around each of the struts (40), the coil winding (44) being controllable to generate a rotating magnetic field; Equipped with the impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field to cause rotation of the impeller (3); the magnetic core (400) comprises or consists of a laminated sheet (85) of soft magnetic material, the soft magnetic material being discontinuous in electrical conductivity in a cross-section transverse to the laminated sheet; An intravascular blood pump (1), wherein the orientation of the seats (85) in the struts (40) relative to the rotation axis (10) is the same for all struts (40).

2. 2. The intravascular blood pump (1) according to claim 1, wherein the material of at least a portion of at least one of the struts (40) is integral with the material of the intermediate region (59) of the backplate (50).

3. 3. An intravascular blood pump (1) according to claim 1 or 2, wherein within each of the struts (40), one of the sheets (85) of soft magnetic material or an intermediate layer between two of the sheets (85) of soft magnetic material is arranged in a plane containing the axis of rotation (10).

4. 3. An intravascular blood pump (1) according to claim 1 or 2, wherein within each of said struts said sheets (85) of soft magnetic material are arranged concentrically around said axis of rotation (10).

5. An intravascular blood pump (1) according to any one of claims 1 to 4, comprising at least one weld (82, 83, 86) bridging a discontinuity in electrical conductivity in the soft magnetic material.

6. 6. The intravascular blood pump (1) according to claim 5, wherein at least one of the at least one welds (82, 83, 86) is arranged on a surface of the back plate (50) opposite the strut (40).

7. 7. An intravascular blood pump (1) according to claim 5 or 6, wherein at least one of the at least one welds is arranged on an end face of the strut (40) opposite the back plate (50).

8. A method for manufacturing a magnetic core (400) for a drive unit (4) of an intravascular blood pump (1), the magnetic core (400) having a rotation axis (10), including a plurality of struts (40) arranged around the rotation axis (10), and a back plate (50) connecting the struts (40), the method comprising the steps of: providing a monoblock (9) comprising or consisting of a laminated sheet (85) of soft magnetic material, said soft magnetic material being discontinuous in terms of electrical conductivity in a cross-section transverse to the laminated sheet; cutting grooves in the monoblock (9) to create the struts (40), whereby the struts (40) are arranged around the axis of rotation (10) and the orientation of the sheets (85) within the struts (40) relative to the axis of rotation (10) is the same for all struts (40); A manufacturing method comprising:

9. 9. The method of claim 8, wherein the grooves are cut in each of the struts (40) such that the sheet (85) of soft magnetic material or one of the intermediate layers between two of the sheets (85) of soft magnetic material is aligned in a plane containing the axis of rotation (10).

10. 10. The method according to claim 8 or 9, wherein the grooves are cut in each of the struts (40) such that the sheets (85) of soft magnetic material are arranged concentrically around the axis of rotation (10).

11. The method according to any one of claims 8 to 10, wherein the back plate (50) is made in such a way that when cutting the grooves in the monoblock (9), the back plate (50) forms one integral piece with the support post (40).

12. A method according to any one of claims 8 to 11, wherein the grooves (49) are cut using electrical discharge machining.

13. The method of claim 12 , wherein the grooves are cut using wire cutting by electrical discharge machining.

14. The method of any one of claims 8 to 11, wherein the grooves are cut using electrochemical machining.

15. A method for manufacturing an intravascular 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 8 to 14.

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