Blood pump

Abstract

To provide an intravascular blood pump for percutaneous insertion into a patient's blood vessel.SOLUTION: A blood pump 1 comprises a pump casing 2 including a blood flow inlet 21 and a blood flow outlet 22, and an impeller 3 disposed in the pump casing 2 so as to be rotatable about an axis of rotation 10. The blood pump 1 comprises a drive unit 4, the drive unit 4 for rotating the impeller 3, the drive unit 4 comprising a magnetic core including a plurality of posts 40 disposed around the axis of rotation 10 and a back plate 50 connecting the posts 40 and extending between the posts 40 in an intermediate area. A coil winding 44 is disposed around each of the posts 40. The coil windings 44 are controllable to create a rotating magnetic field, where the impeller 3 includes a magnetic structure 32 disposed to interact with the rotating magnetic field so as to cause rotation of the impeller 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a blood pump for assisting blood flow in a patient's blood vessel, in particular an intravascular blood pump for percutaneous insertion into a patient's blood vessel. The blood pump has 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 blood pumps, where blood flow is induced by both axial and radial forces. Intravascular blood pumps are inserted into a patient's blood vessel, such as the aorta, by means of a catheter. Blood pumps typically comprise a pump casing having a blood flow inlet and a blood flow outlet connected by a passageway. An impeller or rotor is rotatably supported within the pump casing to induce blood flow along the passageway from the blood flow inlet to the blood flow outlet, the impeller being provided with blades for transporting blood.

[0003] The blood pump is usually driven by a drive unit, which can be an electric motor. For example, US 2011 / 0238172 A1 discloses an extracorporeal blood pump with an impeller that can be magnetically coupled to an electric motor. The impeller includes a magnet arranged adjacent to a magnet in the electric motor. Due to the attractive forces between the magnets in the impeller and in the motor, the rotation of the motor is transferred to the impeller. To reduce the number of rotating parts, it is also known from US 2011 / 0238172 A1 to utilize a rotating magnetic field, where the drive unit has a number of fixed pillars arranged around the axis of rotation, each pillar carrying a wire coil winding and acting as a magnetic core. A control unit supplies voltages to the coil windings in sequence, creating the rotating magnetic field. To provide a sufficiently strong magnetic coupling, the magnetic force must be sufficiently high, which can be achieved by a sufficiently high current supplied to the drive unit or by providing a large magnet, which leads to a large overall diameter of the blood pump.

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

[0005] More specifically, the blood pump in EP 3222301 B1 comprises a pump casing with a blood inlet and a blood outlet, an impeller and a drive unit for rotating the impeller. By rotation of the impeller inside the pump casing about a rotation axis, blood can be transported from the blood inlet to the blood outlet by the blades of the impeller. The drive unit comprises a magnetic core including a number of pillars, preferably six, and a backplate connecting the rear ends of the pillars and acting as a yoke. The pillars are arranged in a circle around the rotation axis when viewed in a plane perpendicular to the rotation axis, each of the pillars having a longitudinal axis preferably parallel to said rotation axis. The backplate has through openings, inside each of them the rear ends of the pillars are received in a close-fitting manner such that the end face of the rear end of each pillar is flush with the rear face of the backplate. In this way, a magnetic connection between the pillars and the backplate is generated between the periphery of the pillars and the internal contour of the opening in the backplate. Each of the pillars has a coil winding arranged around the pillar. The coil windings can be controlled in a coherent manner to generate a rotating magnetic field for driving an impeller, the impeller comprising a magnetic structure in the form of magnets arranged to interact with the rotating magnetic field, thereby causing the impeller to follow its rotation. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to improve the magnetic flux within the magnetic core. [Means for solving the problem]

[0007] The blood pump of the present invention corresponds to the blood pump described above. It can therefore be an axial blood pump or a mixed flow blood pump, pumping partly axially and partly radially (the diameter of a purely centrifugal blood pump is usually too large for intravascular applications). However, according to one aspect of the present invention, the material of at least part of at least one of the pillars of the magnetic core is integral with the material of the intermediate area of ​​the backplate of the magnetic core. Here, the intermediate area of ​​the backplate is the area of ​​the backplate located between the pillars. Preferably, all the pillars are thus integrally connected to the backplate. In other words, at least one pillar and the backplate, preferably the entire magnetic core, can be made of 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 pillars and the backplate is minimized and therefore the magnetic flux is improved. Furthermore, a good mechanical stiffness of the transition between the pillars and the backplate can be achieved.

[0008] Each of the pillars has a longitudinal axis that may be parallel to the axis of rotation. Preferably, the magnetic core comprises a discontinuous soft magnetic material. More preferably, the soft magnetic material of the magnetic core is discontinuous in a cross section, preferably perpendicular to the longitudinal axis of the pillar. In other words, the soft magnetic material of the pillar is discontinuous in a cross section, preferably perpendicular to the direction of the magnetic flux generated by the respective coil winding in the pillar. By dividing or breaking the soft magnetic material in the cross section, eddy currents in the pillar can be reduced or avoided, which can reduce heat generation and energy consumption. Reducing energy consumption is particularly useful for long-term applications of blood pumps, where it is desired that the blood pump be battery-powered to provide mobility to the patient. Also, in long-term applications, the blood pump can be operated without purging, which is only possible if heat generation is low.

[0009] "Discontinuous" in the sense of this document means that the soft magnetic material is divided, separated, partitioned or similarly configured with insulating or other material or gaps, when viewed in any cross section, for example across the longitudinal axis of the pillar, to form strictly separate areas of soft magnetic material or areas that are disconnected but connected at different locations.

[0010] Providing a discontinuous soft magnetic material in a cross-sectional plane transverse to the direction of the magnetic flux reduces eddy currents and therefore heat generation and energy consumption, as explained above. In order not to weaken the magnetic field significantly compared to a continuous or full body (i.e. solid) soft magnetic material, the total amount of soft magnetic material should be maximized while minimizing the continuous areas of soft magnetic material. This can be achieved by providing the soft magnetic material in the form of multiple sheets of soft magnetic material, such as electric steel. In particular, the sheets can form a stack of sheets. The sheets are preferably electrically insulated from each other, for example by providing an adhesive, lacquer, baking enamel, or the like, between adjacent ones of the sheets. Such a configuration can be described as "slotted". Compared to a full body soft magnetic material, the amount of soft magnetic material is only slightly reduced and the amount of insulating material is kept small, so that the magnetic field generated by the slotted pillar is substantially the same as that generated by a solid pillar. In other words, the heat generation and energy consumption can be significantly reduced, while the loss of the magnetic field generated by the insulating material is small.

[0011] The sheets preferably extend substantially parallel to the longitudinal axis of each pillar. In other words, the sheets may extend substantially parallel to the direction of magnetic flux, whereby the pillars are discontinuous in cross sections transverse to or perpendicular to the direction of magnetic flux. It will be understood that the sheets may extend at an angle to the longitudinal axis of each pillar, so long as the soft magnetic material is discontinuous in cross sections transverse to the longitudinal axis. The sheets preferably have a thickness in the range of 25 μm to 1 mm, more preferably 50 μm to about 450 μm, for example 200 μm.

[0012] In particular, a region of a particular type of material, such as a sheet of soft magnetic material, may extend into both the posts and the backplate. Even though the material is discontinuous, the magnetic core may be made of a single block of such material. Such an extension of a region of a particular type of material is not broken by a transition between the posts and the backplate, but is integrally continuous from the posts into an intermediate region of the backplate located between the posts.

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

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

[0015] While the sheets or other structures of soft magnetic material may be formed uniformly, i.e., the sheets within one or all of the columns may have the same thickness or the wires may have the same diameter, non-uniform configurations may be provided. For example, the sheets may have a varying thickness or the wires may have a varying diameter. More specifically, particularly with respect to a stack of sheets, one or more central sheets may have a greater thickness while adjacent sheets toward the ends of the stack may have a smaller thickness. That is, the thickness of the sheets decreases from the center toward 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 greater diameter while the wires at the edge of the column may have a smaller diameter. That is, the diameter of the wires may decrease from the center toward the edges of the bundle, i.e., toward the outermost wires of the bundle. It may be advantageous to provide a larger continuous area of ​​soft magnetic material at the center of the column relative to a cross section transverse to the longitudinal axis of the column, i.e., to provide a relatively thick sheet or wire at the center. This can be advantageous because it can enhance the magnetic flux through the center along the longitudinal axis of each pillar, and the eddy currents in the center are not as significant as those at the sides of the pillar, in other words, the eddy currents in the side regions of the pillar are more significant and can be reduced by the thin sheets or wires in the side regions.

[0016] The diameter of the backplate may be in the range of 3mm to 9mm, such as 5mm or 6mm to 7mm. The thickness of the backplate may be in the range of 0.5mm to 2.5mm, such as 1.5mm. The outer diameter of the blood pump may be in the range of 4mm to 10mm, preferably 7mm. The outer diameter of the multiple pillar configuration may be in the range of 3mm to 8mm, such as 4mm to 7.5mm, preferably 6.5mm.

[0017] As mentioned above, the pole is made of a soft magnetic material such as electric steel (magnetic steel). The pole and backplate can be made of the same material. Preferably, the drive unit, including the pole and backplate, is made of cobalt steel. The use of cobalt steel contributes to reducing the pump size, especially the diameter. As it has the highest magnetic permeability and highest saturation flux density of all magnetic steels, cobalt steel produces the largest amount of magnetic flux for the same amount of material used.

[0018] The dimensions of the pillar, especially the length and cross-sectional area, may vary and depend on various factors. The dimensions of the pillar, as opposed to the dimensions of the blood pump, e.g., the outer diameter, which depend on the application of the blood pump, are determined by the electromagnetic properties, which are adjusted to achieve the desired performance of the drive unit. One of the factors is the magnetic flux density to be achieved through the smallest cross-sectional area of ​​the pillar. The smaller the cross-sectional area, the higher the current required to achieve the desired magnetic flux. However, the higher the current, the more heat will be generated in the wire of the coil due to electrical resistance. It means that a "thin" pillar is preferred to reduce the overall size, but this would require a high current and therefore generate undesirable heat. The heat generated in the wire also depends on the length and diameter of the wire used for the coil winding. To minimize the winding losses (referred to as "copper losses" or "copper power losses" when copper wire is used, as is usually the case), a short wire length and a large wire diameter are preferred. In other words, with a small wire diameter, more heat is generated compared to a thicker wire at the same current. The preferred wire diameter is 0.05 mm to 0.2 mm, for example 0.1 mm. Further factors influencing the dimensions of the pole and the performance of the drive unit are the number of turns of the coil and the outer diameter of the pole including the windings, i.e. the windings. Multiple windings may be arranged in more than one layer around each pole, for example two or three layers may be provided. However, the more layers there are, the more heat will be generated due to the increased length of wire in the outer layer with the larger winding diameter. The increased length of wire may generate more heat due to the higher resistance of the long wire compared to the shorter one. Therefore, a single layer of windings with a small winding diameter would be preferred.

[0019] A typical number of turns, which in turn depends on the length of the post, can be about 50 to about 150, e.g., 56 or 132. Regardless of the number of turns, the coil turns are made of an electrically conductive material, particularly a metal, such as copper or silver. Silver may be preferred over copper, since silver 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 located on an outer surface of the magnetic core, which may be particularly accessible for example for laser welding. The welds bridge discontinuities in electrical conductivity 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 can be located on the surface of the backplate opposite the columns. They can be produced by laser welding. If a material made of laminated sheets is used, the welds preferably bridge adjacent soft magnetic sheets diagonally or laterally.

[0022] In a further aspect of the invention, 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 number of pillars arranged around the axis of rotation and a backplate connecting the pillars. The method comprises the steps of providing a monoblock of magnetically conductive material and cutting slots into the monoblock, thereby creating the pillars such that they are arranged around the axis of rotation and the backplate such that the backplate forms an integral part with the pillars. As pointed out above, an advantage of such manufacturing is the production of a magnetic core with reduced reluctance.

[0023] At least one slot, and preferably all slots that are opposite each other with respect to the axis of rotation, may be produced by cutting through the axis of rotation of the core, so that an even distribution of the columns around the axis of rotation can be easily achieved.

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

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

[0026] In a further aspect of the invention, a method of 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 as described above.

[0027] The foregoing summary, as well as the following detailed description of the preferred embodiments, will be better understood when read in conjunction with the appended drawings. For purposes of illustrating the present disclosure, reference is made to the drawings. However, the scope of the disclosure is not limited to the specific embodiments disclosed in the drawings. [Brief description of the drawings]

[0028] [Figure 1] 1 shows a cross-sectional view of a blood pump. [Diagram 2] FIG. 1 shows a cross-sectional view of a preferred embodiment of a drive unit-impeller configuration. [Figure 3A] 3A to 3C show steps of manufacturing an integrated core for the drive unit according to FIG. 2. [Figure 3B] 3A to 3C show steps of manufacturing an integrated core for the drive unit according to FIG. 2. [Figure 3C] 3A to 3C show steps of manufacturing an integrated core for the drive unit according to FIG. 2. [Figure 4A] 3A-3C depict welds on a unitized core as fabricated according to FIGS. 3A-3C. [Figure 4B]3A-3C depict welds on a unitized core as fabricated according to FIGS. 3A-3C. [Figure 4C] 3A-3C depict welds on a unitized core as fabricated according to FIGS. 3A-3C. [Figure 5A] 1A-1D show cross sections through a post according to various embodiments. [Figure 5B] 1A-1D show cross sections through a post according to various embodiments. [Figure 5C] 1A-1D show cross sections through a post according to various embodiments. [Figure 5D] 1A-1D show cross sections through a post according to various embodiments. [Figure 5E] 1A-1D show cross sections through a post according to various embodiments. [Figure 5F] 1A-1D show cross sections through a post according to various embodiments. [Figure 5G] 1A-1D show cross sections through a post according to various embodiments. [Figure 5H] 1A-1D show cross sections through a post according to various embodiments. [Figure 5I] 1A-1D show cross sections through a post according to various embodiments. [Figure 5J] 1A-1D show cross sections through a post according to various embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] 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 called a catheter pump, and is deployed in a patient's blood vessels using a catheter 25. The blood inlet 21 is at the end of a flexible cannula 23 which, in use, may be placed through a heart valve, such as the aortic valve. The blood outlet 22 is located in the side of the pump casing 2 and may be placed in a heart vessel, such as the aorta. The blood pump 1 is electrically connected with an electrical wire 26 extending through the catheter 25 for supplying power to the blood pump 1 to drive the pump 1 using a drive unit 4, as will be explained in more detail below.

[0030] If the blood pump 1 is intended to be used in long-term applications, i.e. in situations where the blood pump 1 is implanted in a patient for weeks or even months, power is preferably supplied by means of a battery. This allows the patient to be mobile, since the patient is not connected to a base point by a cable. The battery may be carried by the patient and may supply electrical energy to the blood pump 1, for example wirelessly.

[0031] Blood is conveyed along a passage 24 connecting a blood inlet 21 and a blood outlet 22 (the blood flow is indicated by an arrow). An impeller 3 is provided for conveying blood along the passage 24 and is rotatably mounted in the pump casing 2 around a rotating shaft 10 by means of a first bearing 11 and a second bearing 12. The rotating shaft 10 is preferably the longitudinal axis of the impeller 3. Both bearings 11, 12 are contact type bearings in this embodiment. However, at least one of the bearings 11, 12 could be a non-contact type bearing, such as a magnetic or hydrodynamic bearing. The first bearing 11 is a pivot bearing with a spherical bearing surface allowing rotational and some pivotal movement. A pin 15 is provided forming one of the bearing surfaces. The second bearing 12 is arranged in a support member 13 for stabilizing the rotation of the impeller 3, the support member 13 having at least one opening 14 for the blood flow. The impeller 3 is provided with blades 31 for transporting blood as it rotates. Rotation of the impeller 3 is caused by a drive unit 4 which is magnetically coupled to magnets 32 at the end portion of the impeller 3. The illustrated blood pump 1 is a mixed type blood pump, the main direction of flow is axial. It will be understood that the blood pump 1 could also be a purely axial blood pump depending on the configuration of the impeller 3, in particular the blades 31.

[0032] The blood pump 1 comprises an impeller 3 and a drive unit 4. The drive unit 4 includes a number of pillars 40, such as six pillars 40, only two of which are visible in the cross-sectional view of FIG. 1. The pillars 40 are arranged parallel to the axis of rotation 10, more specifically, the longitudinal axis of each of the pillars 40 is parallel to the axis of rotation 10. One end of the pillars 42 is disposed adjacent to the impeller. A coil winding 44 is disposed around the pillars 40. The coil windings 44 are in turn controlled by a control to create a rotating magnetic field. Part of the control unit is a printed circuit board 6 connected to electrical wires 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 to cause rotation of the impeller 3 around the axis of rotation 10.

[0033] To close the magnetic flux path, a backplate 50 is arranged at the end of the pillar 40 opposite the impeller side of the pillar. The pillar 40 acts as a magnetic core and is made of a suitable material, in particular a soft magnetic material, such as steel or a suitable alloy, in particular cobalt steel. Similarly, the backplate 50 is made of a suitable soft magnetic material, such as cobalt steel. The backplate 50 enhances the magnetic flux, which allows a reduction in the overall diameter of the blood pump 1, which is important for intravascular blood pumps. For the same purpose, a yoke 37, i.e. an additional impeller backplate, is provided in the impeller 3 on the side of the magnet 32 ​​facing away from the drive unit 4. The yoke 37 in this embodiment has a conical shape to guide the blood flow along the impeller 3. The yoke 37 may also be made of cobalt steel. One or more washout channels may be formed in the yoke 37 or in the magnet 32, which extend towards the central bearing 11.

[0034] Fig. 2 shows a cross-sectional view of a preferred embodiment of a drive unit-impeller arrangement for a blood pump according to Fig. 1. As can be seen in Fig. 2, the impeller end 420 of the pillar 40 does not extend radially beyond the winding 44. Rather, the cross section of the pillar 40 is constant in the direction of the longitudinal axis LA of the pillar 40. Thus, the pillars 40 are avoided from approaching each other, since this would cause a partial magnetic short circuit and, as a result, a reduction in the power of the electric motor of the blood pump.

[0035] The drive unit according to Fig. 2 may include at least two, at least three, at least four, at least five, or preferably six pillars 40. A larger number of pillars 40, such as nine or twelve, may also be possible. Due to the cross-sectional view, only two pillars 40 are visible. The pillars 40 and the backplate 50 form the magnetic core 400 of the drive unit 4, which may have a diameter of less than 10 mm.

[0036] The magnetic core 400 includes the magnet components of the drive unit 4, the post 40 and the backplate 50, in one single piece or monoblock. The monoblock consists of a discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity. The discontinuous soft magnetic material includes a number of sheets 85 made of a ferromagnetic material and stacked together. The stacking direction is aligned in the direction of the longitudinal axis LA of the post 40 and is labeled by the arrow DL. As shown, the post 40 is aligned parallel to the axis of rotation 10.

[0037] The coil winding 44 extends to the impeller end 420 of the pillar 40. This has the advantage that magnetomotive forces can be generated along the entire pillar 40. The magnetic core 400 includes a protrusion 401 at the rear end 450 of the pillar 40, which protrudes radially relative to the pillar 40. This protrusion 401 can be a stop for the coil winding 44 towards the backplate 50. Since the integrated magnetic core 400 has a high rigidity between the backplate 50 and the pillar 40, a spacer between the pillars 40 at the impeller end 420 of the pillars can be omitted. The integrated magnetic core 400 provides the advantage that an optimal magnetic connection between the pillar 40 and the backplate 50 can be achieved. The magnetic core 400 can have a diameter of less than 10 mm.

[0038] Figures 3A-3C show the steps of manufacturing a magnetic core 400 for a drive unit 4 of the drive unit-impeller configuration as shown in Figure 2. Figure 3A shows in perspective view a cube-shaped monoblock 9 forming the workpiece for manufacturing the magnetic core 400. The monoblock 9 consists of discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity. It includes sheets 85 oriented in a stacking direction DL extending along the main plane of the sheets 85. The sheets 85 are each joined to their respective neighboring sheets by a joining layer of electrically non-conductive material, not explicitly shown in Figures 3A-3C.

[0039] 3B shows the magnetic core 400 in a semi-finished state in which it has been processed, e.g. transformed, from a cubic monoblock 9 into a substantially cylindrical body 94. In this processing step, the protrusions 401 are produced. The reduced diameter section 404 of the body 94, which forms the peripheral surface of the post 40 of the magnetic core 400, is produced to have a diameter corresponding to the outer radius of the outermost convex side surface 842 of the post 40.

[0040] The body 94 can then be further fabricated to produce the magnetic core 400 as shown in FIG. 3C. For this production step, electrical discharge machining can be used. In particular, electrical discharge machining by wire cutting can be applied to produce the slots 49 that separate the pillars 40 from one another. Inside the slots, space is provided for the coil windings 44. At the base of the slots 49, an intermediate section 59 of an integral backplate 50 extends between the rear ends of the pillars 40. The intermediate section is integral with the pillars 40 and with the backplate 50. The entire magnetic core is therefore formed by a monoblock 9.

[0041] The lamination direction DL in the magnetic core 400 is such that it is parallel to the axis of rotation 10. It may be acceptable that the lamination direction DL in the base plate 50 is not parallel to the magnetic currents between the posts 40 in the base plate 50. It is also possible to fabricate the magnetic core 400 from coiled soft magnetic sheet material separated by electrically non-conductive layers. The lamination direction DL in the base plate 50 is then always circumferential, which is advantageous for avoiding eddy currents in the magnetic flux in the base plate 50.

[0042] 4A-4C show how one or more welds can be provided on the integrated core surface as produced 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 and across the cross section of the body 94 to be cut out of the monoblock 9. The weld seams 82, 83 run perpendicular to the lamination direction DL of the sheets 85. In this way, discontinuous sheets of soft magnetic material are connected to one another. 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). As an alternative to or in addition to the welds on the opposite side, one or more weld seams may be provided on the side of the monoblock 9 at the level of the backplate 50, completely or at least partially surrounding the backplate 50. The sheets 85 have a better mechanical connection to each other due to the weld seams 82, 83 and are furthermore electrically connected. The latter has the advantage that current can flow from any position of the discontinuous soft magnetic material to each position of the electrical connection of the body 94 that may be required, for example, for electrical discharge machining. In this way, electrical discharge machining is greatly facilitated. Furthermore, a higher process reliability is achieved, since the backplate-pillar unit cut out of the body 94 cannot disintegrate due to delamination. Preferably, laser welding is applied. It may be advantageous to apply the welding power twice or even multiple times to the same weld.

[0043] 5A-5J show various embodiments of the pillar in cross section. 5A-5D show an embodiment in which the pillar is grooved, i.e. formed of multiple sheets 171 insulated from each other by an insulating layer 172. The insulating layer 172 can include adhesive, lacquer, baked enamel, or the like. 5A and 5B show an embodiment in which the thickness of the sheets 171 is uniform. The thickness can be in the range of 25 μm to 450 μm. The sheet 171 shown in FIG. 5A has a greater thickness than the sheet 171 shown in FIG. 5B. The sheets in FIG. 5C have a varying thickness, with the central sheet having the greatest thickness and the outermost sheet having the least thickness. This can be advantageous because eddy currents in the side regions of the pillar are more significant and can be reduced by a thinner sheet. The eddy currents in the central area are less significant and a relatively thick central sheet can help improve the magnetic flux. The orientation of the sheets 171 may be different, as exemplarily shown in FIG. 5D, so long as the soft magnetic material shown in cross section, i.e., in a cross section transverse to the direction of magnetic flux, is discontinuous or interrupted.

[0044] 5E and 5F show an embodiment in which the pillar 141 is formed by a bundle of wires 181 insulated from each other by an insulating material 182. The insulating material 182 can be present as a coating on each of the wires 181 or can be a matrix in which the wires 181 are embedded. In the embodiment of FIG. 5E, all 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 with a sheet with varying thickness. 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 the wires have the same diameter. Additionally alternatively, the wires 183 may have a polygonal cross-sectional area, such as rectangular, square, etc., to further minimize the insulating layer 184 between the wires 183.

[0045] Alternatively, the discontinuous cross section of the pillar 141 may be created by metal particles 185 embedded in a polymer matrix 186 as shown in FIG. 5I, or by steel wool or other porous structures impregnated with an insulating matrix. A porous and therefore discontinuous structure of soft magnetic material may also be produced by a sintering process or a high pressure molding process, in which case the insulating matrix may be omitted, since the insulating layer is formed automatically by oxidation of the soft magnetic material due to exposure to air. Still alternatively, the pillar 141 may be formed of rolled sheets 187 of soft magnetic material, in which case the layers of the rolled sheets 187 are separated by insulating layers 188 as shown in FIG. 5J. This also results in a discontinuous cross section in the sense of the present invention, which reduces eddy currents in the pillar 141 or pillar 40.

Claims

1. An intravascular blood pump (1) for percutaneous insertion into a blood vessel of a patient, comprising: A pump casing (2) having a blood flow inlet (21) and a blood flow outlet (22); an impeller (3) rotatably disposed within the pump casing (2) about an axis of rotation (10), the impeller (3) having blades (31) sized and shaped 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) comprising a magnetic core (400) including a plurality of posts (40) arranged around the rotation axis (10) and a backplate (50) connecting the posts (40) and extending between the posts (40) in an intermediate region (59); a coil winding (44) disposed around each of the posts (40), the coil winding (44) being controllable to create a rotating magnetic field; Equipped with An intravascular blood pump (1), wherein the impeller (3) includes a magnet structure (32) arranged to interact with the rotating magnetic field to cause rotation of the impeller (3), An intravascular blood pump (1), characterized in that the material of at least a portion of at least one of said posts (40) is integral with the material of said intermediate region (59) of said backplate (50).

2. 2. An intravascular blood pump (1) according to claim 1, characterized in that the magnetic core (400) comprises or consists of a soft magnetic material which is discontinuous in terms of electrical conductivity in a cross section transverse to the axis of rotation (10).

3. 3. An intravascular blood pump (1) according to claim 2, characterized in that the soft magnetic material comprises laminated sheets (85) of soft magnetic material.

4. 4. An intravascular blood pump (1) according to claim 2 or 3, characterized in that the sheet (85) of soft magnetic material is oriented parallel to the axis of rotation (10).

5. An intravascular blood pump (1) according to any one of claims 2 to 4, characterized in that it comprises 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) of claim 5, characterized in that at least one of the at least one welds (82, 83, 86) is disposed on a surface of the backplate (50) opposite the column (40).

7. 7. An intravascular blood pump (1) according to claim 5 or 6, characterized in that at least one of the at least one welded portion is arranged on an end face of the column (40) opposite the backplate (50).

8. 1. A method of manufacturing a magnetic core (400) for a drive unit (4) of an intravascular blood pump (1), said magnetic core having an axis of rotation (10) and including a number of pillars (40) arranged around said axis of rotation (10), and a backplate (50) connecting said pillars (40), characterized in that the method comprises the steps of: providing a monoblock (9) of magnetically conductive material; and cutting slots into said monoblock (9) thereby creating said pillars (40) such that they are arranged around said axis of rotation (10) and said backplate (50) such that said backplate (50) forms one integral part with said pillars (40).

9. 9. A method according to claim 8, characterized in that at least one of said slots (49) is cut through said rotating shaft (10).

10. A method according to claim 8 or 9, characterized in that the slots (49) are cut so that the posts (40) all have the same length.

11. 11. The method according to any one of claims 8 to 10, characterized in that the slots (49) are cut such that the backplate (50) has a thickness less than the maximum cross-sectional dimension of the post (40) transverse to its longitudinal axis (LA).

12. A method according to any one of claims 8 to 11, characterized in that the slots (49) are cut by means of electro-discharge machining.

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

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

15. A method for making an intravascular blood pump (1) having a drive unit (4) with a magnetic core (400), characterized in that said magnetic core (400) is made according to any one of claims 8 to 14.

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