Blood pump

Abstract

To provide an intravascular blood pump for percutaneous insertion into a patient's blood vessel.SOLUTION: A blood pump includes: a pump casing having a blood inflow port and a blood outflow port; an impeller disposed in the pump casing so as to be rotatable around a rotation axis 10; and a drive unit including a plurality of posts 40 disposed around the rotation axis 10. Each of the posts 40 has an impeller-side end part 420 facing toward the impeller having a front surface 42 that faces the impeller. A coil winding is disposed around each of the posts 40 and is controllable to generate a rotating magnetic field. The impeller includes a magnetic structure 32 that is disposed to interact with the rotating magnetic field so as to cause rotation of the impeller. The front surface 42 of at least one of the posts 40 includes a concavity in which the front surface 42 is inclined downwards towards a central area of the front surface 42 so as to concentrate at least a part of magnetic field lines extending through the front surface 42.SELECTED DRAWING: Figure 3B

Description

[Technical Field]

[0001] The present invention relates to an intravascular blood pump for assisting blood flow within a patient's blood vessels, and in particular to an intravascular blood pump for percutaneous insertion into a patient's blood vessels. The blood pump has an improved drive unit. [Background technology]

[0002] Different types of blood pumps are known, such as axial-flow blood pumps, centrifugal (i.e., radial) blood pumps, or mixed-flow 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, using a catheter. Blood pumps typically include a pump casing having a blood inlet and a blood 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 inlet to the blood outlet, and the impeller is provided with blades for transporting the blood.

[0003] Blood pumps are typically driven by a drive unit, which can be an electric motor. For example, WO 2017 / 162619(A1) discloses an intravascular blood pump having an impeller magnetically coupled to an electric motor. The impeller includes a magnet disposed adjacent to an electrically magnetized zone in the electric motor. Rotation of the motor is transmitted to the impeller due to attractive forces between the electrically magnetized zones in the impeller and the motor. That is, the drive unit includes multiple fixed pillars arranged around the impeller's rotation axis, each of which holds a wire coil winding and serves as a magnetic core. A control unit sequentially supplies voltage to the coil windings, creating a rotating magnetic field that rotates the magnetically coupled impeller.

[0004] More specifically, the intravascular blood pump in WO 2017 / 162619(A1) 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 within the pump casing around a rotation axis causes blood to be transported from the blood inlet to the blood outlet by the impeller blades. The drive unit includes six pillars 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, and each pillar has a longitudinal axis parallel to the rotation axis. Each pillar has a shaft and an inclined head portion at the impeller-side end of the shaft facing the impeller, the head portion extending radially beyond the shaft to form a shoulder that can serve as an axial stop for a coil winding disposed around each pillar. A control unit sequentially supplies voltage to the coil windings to generate a rotating magnetic field. The impeller comprises a magnet structure arranged to interact with a rotating magnetic field, thereby causing the impeller to follow its rotation.

[0005] During operation, adjacent poles may have different magnetizations. As a result, magnetic flux extending through the poles tends to bypass the impeller and flow between them. This magnetic flux is lossy for torque generation. A disadvantage of current technology is that the head portions extending radially beyond the shaft have a significantly smaller distance from each other. Therefore, there is significant parasitic magnetic flux between the head portions, which is lossy for torque generation. Such parasitic magnetic flux can be offset by placing a magnetically insulating material, such as a magnet, between the head portions, but available space is very limited, and to achieve adequate insulation, the polarization of the magnet would have to be changed periodically, which is difficult. The present invention aims to improve drive units in this regard. Summary of the Invention [Means for solving the problem]

[0006] The blood pump of the present invention may correspond to the blood pumps described above. It may therefore be an axial-flow 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 front face of the impeller end of at least one of the pillars—preferably each of the pillars—includes a recess sloping downwardly toward a central region of the front face such that the front face focuses at least a portion of the magnetic field lines extending through the front face.

[0007] The magnetic field lines of magnetic flux leaving and entering the surface of a component made of magnetic material extend perpendicular to the surface; that is, they enter and exit perpendicular to the surface plane. By providing a depression in the front face of the pillar, i.e., a recess in which the front face slopes downward toward the center of the front face, the magnetic field lines extending into and out of the pillar through the front face are forced to extend closer to the central axis of the pillar. As a result, because the magnetic field lines never cross each other, they are focused in front of the impeller-side end of the pillar and directed as a bundle toward the impeller. This reduces parasitic magnetic flux between adjacent pillars.

[0008] The inclination of the depressions relative to the surface plane is less than 90°, preferably 0° to 30°.

[0009] Preferably, the indentation extends all the way around the front face. In other words, the indentation may start from the outer edge of the front face. This also has the effect that the outermost magnetic field lines are also affected by the inclination of the indentation. The outermost magnetic field lines are the ones that have the greatest tendency to bridge to adjacent pillars. Therefore, the indentation is most effective if it extends all the way around the front face of the pillar.

[0010] It may be sufficient for the recess to extend around the front surface of the pillar on at least two, preferably exactly two opposite sides of the front surface, i.e., on those sides closest to the adjacent pillars. This may be particularly advantageous when the pillars are, for example, cylindrical and therefore circular in cross section. The risk of magnetic field lines bridging to adjacent pillars is greatest where the pillars are a short distance from each other. Therefore, the recess is sufficiently effective if it extends around the front surface of the pillar only on the two sides located closest to each adjacent pillar.

[0011] Nevertheless, it is preferable that the perimeter of the recess coincide with the perimeter of the front face. In this way, the inclination of the recess causes the outermost magnetic field lines to be directed along the entire perimeter of the front face toward the center of the front face. As mentioned above, the outermost magnetic field lines are those that have the greatest tendency to turn away from the impeller. Therefore, the recess is most effective when its perimeter coincides with the perimeter of the front face.

[0012] Since it may be sufficient to direct the outermost magnetic field lines towards the center, the depression may have a flat bottom. Therefore, at least the region at the periphery of the depression is sloping downwards. In this case, the depression may have straight sloping sidewalls when viewed in a cross-sectional plane extending vertically through the front face, or it may have curved sloping sidewalls when viewed in a cross-sectional plane extending vertically through the front face. Curved sloping sidewalls with an increasing slope towards the periphery of the depression have the effect of maximizing the binding effect on the outermost magnetic field lines.

[0013] Alternatively, the recess may have a curved cross-section with a curved bottom rather than a flat bottom when viewed in a cross-sectional plane extending vertically through the front face, so that the centering effect on the magnetic field lines gradually decreases from the periphery of the recess towards its centre.

[0014] Alternatively, the recesses may have a triangular cross section when viewed in a cross-sectional plane extending vertically through the front surface. In this way, the maximum depth of the recesses may be increased. The deeper the recesses, the greater the distance between each portion of the front surface of the pillar and the magnetic structure of the impeller, resulting in a reduction in the axial magnetic force generated between the pillar and the impeller. In particular, reducing the axial magnetic force can increase the ratio between magnetic torque and axial magnetic force, which is an important number for the development of magnetically driven intravascular blood pumps. This ratio is important because the magnetic flux that can be generated is generally limited, and therefore it is desirable to use as much of it as possible for torque generation. The technical effect of the recesses is a reduction in the axial force acting axially on the rotor without a loss of motor power, or alternatively, an increase in motor power for the same total magnetic flux.

[0015] According to a preferred embodiment of the present invention, this ratio can be further increased by downwardly inclining the front surface of the recess in the radially outward direction (in addition to being inclined downwardly toward its central region). Therefore, with respect to the axis of rotation, the radially inner region of the front surface of the recess protrudes axially more than the radially outer region of the front surface of the recess. Again, the result is that the maximum depth of the recess is increased. As mentioned above, the deeper the recess, the greater the distance between the respective portions of the front surface of the pillar and the magnetic structure of the impeller, resulting in a reduction in the axial magnetic force generated between the pillar and the impeller. Therefore, the ratio between magnetic torque and axial magnetic force can be further increased by downwardly inclining the front surface of the recess in the radially outward direction.

[0016] Another important effect achieved by the downward inclination of the front face in the radially outward direction is that the concentrated flux of magnetic field lines is directed radially outward and therefore also impinges radially outward on the magnetic structure of the impeller compared to a horizontal front face. This has a positive effect on the achievable magnetic torque. Again, this results in an improvement in the ratio of magnetic torque to axial magnetic force. Therefore, the positive effect of the downward inclination of the front face in the recess in the radially outward direction on the ratio of magnetic torque to axial magnetic force is twofold.

[0017] According to a preferred embodiment of the present invention, the combination of the inclination of the front surface of the recess both in the center and radially outward direction results in the recess being open towards the side of the pillar, i.e. towards the side located radially outward relative to the axis of rotation. Preferably, the pillar has a triangular cross section with three sides, one of which is located radially outward relative to the axis of rotation compared to the other two sides. In such a case, the recess is open towards one of the three radially outward sides of the pillar.

[0018] In all of the above variants, the depressions may preferably have a maximum depth of 0.05 mm to 0.3 mm.

[0019] According to another aspect of the invention, the pillars have impeller-side ends that do not extend radially beyond the impeller-side ends of the respective coil windings disposed therearound, where the term "radially" refers to a direction transverse to, and preferably perpendicular to, the longitudinal axis of the respective pillar. In other words, the pillars do not have a special head portion. Instead, the pillars preferably have a constant cross section, at least in their impeller-side end region, and more preferably along their entire length.

[0020] The advantage of headless pillars is that magnetic losses due to parasitic magnetic flux between adjacent pillars are reduced due to the greater distance between them. The result is again that the ratio of achievable magnetic torque to magnetic axial force between the drive unit and the impeller is increased compared to the pump described in WO 2017 / 162619 A1, in which the pillars extend with their impeller-side ends radially beyond the impeller-side ends of their respective coil windings.

[0021] According to a further aspect of the present invention, the pillars may each include a soft magnetic material that is discontinuous in a cross section transverse to, preferably perpendicular to, the longitudinal axis of the respective pillar, which axis is preferably parallel to the axis of rotation, as described in further detail in WO 2019 / 057636 A1. "Discontinuous" in the sense of the present invention means that the soft magnetic material is divided, separated, partitioned, or similarly configured using insulating or other materials or gaps when viewed in any cross section transverse to the longitudinal axis, to form strictly separated areas of soft magnetic material or areas that are disconnected but connected at different locations. In other words, the soft magnetic material of the pillars is discontinuous in a cross section transverse to, preferably perpendicular to, the direction of the magnetic flux generated by each coil winding in the pillar. Providing a discontinuous soft magnetic material in a cross-sectional plane transverse to the direction of the magnetic flux reduces eddy currents, which further enhances the effectiveness of the intravascular blood pump.

[0022] Preferably, at least one weld is provided on the surface (811) of the discontinuous soft magnetic material, and the weld bridges at least one discontinuity in electrical conductivity within the discontinuous soft magnetic material. The weld allows for easy fabrication of magnetic cores or portions thereof from the discontinuous soft magnetic material. That is, when separating the magnetic core, or a column for the magnetic core, from a larger workpiece of discontinuous soft magnetic material, the discontinuous soft magnetic material may delaminate or otherwise lose its integrity due to the machining forces applied to the workpiece during the separation process. This is particularly significant due to the very small dimensions of the magnetic core, and particularly its column, and can even occur when electrical discharge machining, particularly wire-cut electrical discharge machining, is used to separate the magnetic core or its column from the workpiece. The use of a weld applied to the workpiece prior to the separation step improves the mechanical stability of the discontinuous material. If electrical discharge machining is used to cut the magnetic core or column from the workpiece, it also improves current flow to the cutting location. The weld or welds may later form part of the core or post. Specifically, the impeller-side end face of the post oriented transverse to the axis of rotation exposes discontinuous material. Thus, the weld or welds may be disposed on the impeller-side surface of the post.

[0023] The drive unit may include a backplate connecting the rear ends of the poles. Like the poles, the backplate may include discontinuous soft magnetic material. Because the magnetic flux in the backplate is substantially transverse to or perpendicular to the axis of rotation, the soft magnetic material of the backplate may be made discontinuous in a cross section parallel to the axis of rotation. Alternatively, the poles and backplate may be made from a monoblock of discontinuous soft magnetic material such that the soft magnetic material of the backplate and the discontinuous soft magnetic material of the poles are discontinuous in the same direction, preferably in a cross section perpendicular to the axis of rotation. Except therefor, substantially all of the features and explanations set forth above regarding the discontinuous material of the poles also apply to the backplate. However, the backplate may alternatively be formed of a continuous, i.e., solid, soft magnetic material.

[0024] According to one preferred embodiment of the drive unit, which includes a backplate connecting the rear ends of the poles, the material of at least one of the poles is integral with the material of the intermediate section of the backplate. Here, the intermediate section of the backplate is the section of the backplate located between the poles. Preferably, all poles are integrally connected to the backplate in this manner. In other words, at least one pole and the backplate of the drive unit, and preferably the entire core, can be made from a single block of material, which may also be called a monoblock. The advantage of such a core is that the magnetic resistance at the transition between the pole and the backplate is minimized, thus improving magnetic flux. Furthermore, good mechanical rigidity can be achieved at the transition between the pole and the backplate.

[0025] According to another preferred embodiment of the drive unit, which includes a backplate connecting the rear ends of the poles, at least one of the poles, and preferably all of the poles, contacts the backplate with their respective rear end faces. This offers the advantage that the quality of the magnetic connection between the poles and the backplate can be independent of the quality of the mechanical fastening of the poles to the backplate. For example, the poles can be mechanically fastened to the backplate in corresponding recesses in the backplate or by using an adhesive provided around the rear ends of the poles. Therefore, a good magnetic connection, and therefore a good magnetic flux, can be achieved directly through the rear end faces of the poles into the backplate without being forced to accept constraints regarding the mechanical properties of the mechanical connection between the poles and the backplate. Furthermore, when the rear ends of the poles are received in appropriately sized recesses in the backplate, a magnetic path for the transmission of magnetic flux is established, which may exist in addition to the peripheral transmission of magnetic flux.

[0026] Therefore, in this case, the pillars can be magnetically connected to the backplate at corresponding contact planes of the backplate. The contact planes are preferably arranged parallel to the rear end faces of the pillars. Preferably, they are arranged perpendicular to the rotation axis. Preferably, the entire surface area of ​​the rear end faces of the pillars is in contact with the backplate. This significantly reduces the magnetic resistance of the connection between the pillars and the backplate. The unevenness of the contact planes of the rear end faces and the backplate is preferably such that the resulting gap is 10 μm or less.

[0027] The backplate, like the pillars, is preferably made of a soft magnetic material such as electric steel (magnetic steel) or other material suitable for closing a magnetic flux circuit, preferably cobalt steel. The diameter of the backplate can be in the range of 3 mm to 9 mm, e.g., 5 mm or 6 mm to 7 mm. The thickness of the backplate can be in the range of 0.5 mm to 2.5 mm, e.g., 1.5 mm. The outer diameter of the blood pump can be in the range of 4 mm to 10 mm, preferably 7 mm. The outer diameter of the multiple pillar configuration can be in the range of 3 mm to 8 mm, e.g., 4 mm to 7.5 mm, preferably 6.5 mm.

[0028] As mentioned above, the pole is made of a soft magnetic material such as electrical steel (magnetic steel). The pole and backplate can be made of the same material. Preferably, the magnetic core of the drive unit, including the pole and backplate, is made of cobalt steel. The use of cobalt steel contributes to reducing the pump size, particularly the diameter. Because it has the highest magnetic permeability and highest saturation magnetic flux density of all magnetic steels, cobalt steel generates the largest amount of magnetic flux for the same amount of material used.

[0029] The dimensions of the pillar, particularly its length and cross-sectional area, vary and depend on various factors. The dimensions of the pillar, as opposed to the dimensions of the blood pump, e.g., its 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 minimum cross-sectional area of ​​the pillar. The smaller the cross-sectional area, the higher the current required to achieve the desired magnetic flux. However, higher current generates more heat in the coil wire due to electrical resistance. Even more importantly, if the pillar cross-section is too small, the stator material will quickly become magnetically saturated. This means that "thin" pillars are preferred to reduce the overall size, but this requires high current and therefore will generate 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 (referred to as "copper loss" or "copper power loss" when copper wire is used, as is usually the case). In other words, a smaller wire diameter generates more heat than a thicker wire at the same current. A preferred wire diameter is 0.05 mm to 0.2 mm, e.g., 0.1 mm. Additional factors affecting the dimensions of the pole and the performance of the drive unit are the number of windings in the coil and the outer diameter of the pole including the windings. Multiple windings may be arranged around each pole in more than one layer, e.g., 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 long wire compared to shorter wire. Therefore, although a single layer of windings with a small winding diameter may be preferred, more than one winding is usually provided due to the required power.

[0030] 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 because it has an electrical resistivity that is about 5% lower than that of copper.

[0031] Preferably, at least one pillar, and more preferably each pillar, has a triangular cross section transverse to the pillar's longitudinal axis. Preferably, the pillar cross section is triangular along its entire length. Such pillars can be densely packed around the axis of rotation, allowing the triangular pillars to utilize a high percentage of the available space inside the pump housing. Preferably, one side of the triangle points outward from the axis of rotation and is curved. The curvature is curved around the axis of rotation. The radius of the curvature preferably corresponds to the radius of the outer diameter defined by the pillars arranged around the axis of rotation. Such curvature allows for further space utilization inside the cylindrical pump housing to be achieved.

[0032] 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 present disclosure is not limited to the specific embodiments disclosed in the drawings. [Brief explanation of the drawings]

[0033] [Figure 1] 1 shows a cross-sectional view of an intravascular blood pump. [Figure 2] 1 shows a cross-sectional view of a first embodiment of a drive unit-impeller arrangement. [Figure 3A] 3 shows a side view and a perspective view of the magnetic core of the drive unit of the drive unit-impeller arrangement according to FIGS. 1 and 2; [Figure 3B] 3 shows a side view and a perspective view of the magnetic core of the drive unit of the drive unit-impeller arrangement according to FIGS. 1 and 2; [Figure 4]3C shows a schematic diagram of the unwound six pillars of the magnetic core shown in FIGS. 3A and 3B. [Figure 5A] 10A-10C show side views of the impeller end of the pillar according to four different embodiments, respectively. [Figure 5B] 10A-10C show side views of the impeller end of the pillar according to four different embodiments, respectively. [Figure 5C] 10A-10C show side views of the impeller end of the pillar according to four different embodiments, respectively. [Figure 5D] 10A-10C show side views of the impeller end of the pillar according to four different embodiments, respectively. [Figure 6A] 3 shows a spacer for the drive unit-impeller arrangement according to FIG. 2 in a perspective view. FIG. [Figure 6B] 3B shows a front view of the spacer of FIG. 3A. [Figure 6C] 3C shows a side view of the spacer of FIGS. 3A and 3B. FIG. [Figure 7A] 3 shows a perspective view of the first layer of the backplate with openings for the posts of the drive units of the arrangement according to FIG. 2; [Figure 7B] FIG. 3 shows a perspective view of the second layer of the backplate without openings for the posts of the drive units of the configuration of FIG. 2. [Figure 7C] FIG. 7C illustrates a cross-sectional view of an assembled backplate including the first and second layers of FIGS. 7A and 7B. [Figure 8A] 3A-3D show stages of manufacturing an intermediate product for the further manufacturing of a column for a drive unit of the configuration according to FIG. 2. [Figure 8B] 3A-3D show stages of manufacturing an intermediate product for the further manufacturing of a column for a drive unit of the configuration according to FIG. 2. [Figure 8C] 3A-3D show stages of manufacturing an intermediate product for the further manufacturing of a column for a drive unit of the configuration according to FIG. 2. [Figure 8D] 3A-3D show stages of manufacturing an intermediate product for the further manufacturing of a column for a drive unit of the configuration according to FIG. 2. [Figure 9A] FIG. 5D shows a group of welds on the intermediate product according to FIG. 5C. [Figure 9B] FIG. 5D shows a group of welds on the intermediate product according to FIG. 5C. [Figure 9C] FIG. 5D shows a group of welds on the intermediate product according to FIG. 5C. [Figure 10] 8A-9C show perspective views of a post separated from an intermediate product as prepared according to FIGS. 8A-9C. [Figure 11] 9B shows a planar front view of the intermediate product of FIG. 9A with two weld seams and two cross sections of the pillars that will be cut out from the intermediate product. [Figure 12] FIG. 1 shows a front view of the end face of a column with a weld. [Figure 13] 10 shows a cross-sectional view of a second embodiment of a drive unit-impeller configuration. [Figure 14A] 14A to 14C show steps for manufacturing an integrated core for the drive unit according to FIG. 13. [Figure 14B] 14A to 14C show steps for manufacturing an integrated core for the drive unit according to FIG. 13. [Figure 14C] 14A to 14C show steps for manufacturing an integrated core for the drive unit according to FIG. 13. [Figure 15A] FIG. 10 illustrates how one or more welds can be provided on the surface of the integrated core. [Figure 15B] FIG. 10 illustrates how one or more welds can be provided on the surface of the integrated core. [Figure 15C] FIG. 10 illustrates how one or more welds can be provided on the surface of the integrated core. DETAILED DESCRIPTION OF THE INVENTION

[0034] Referring to FIG. 1 , a cross-sectional view of blood pump 1 is shown. Blood pump 1 comprises pump casing 2 having blood inlet 21 and blood outlet 22. Blood pump 1 is designed as an intravascular blood pump, also known as a catheter pump, and is deployed within a patient's blood vessels using catheter 25. 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. Blood outlet 22 is located within the side of pump casing 2 and may be placed within a heart vessel, such as the aorta. Blood pump 1 is electrically connected to electrical wires 26 extending through catheter 25 for providing power to blood pump 1 to drive pump 1 using drive unit 4, as described in more detail below.

[0035] If the blood pump 1 is intended for use in a long-term application, i.e., in a situation where the blood pump 1 is implanted in a patient for several weeks or even months, power is preferably supplied using a battery. This allows the patient to be mobile, as the patient is not connected by a cable to a base point. The battery may be carried by the patient and may supply electrical energy to the blood pump 1, for example, wirelessly.

[0036] Blood is transported 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 to transport blood along the passage 24 and is rotatably mounted within the pump casing 2 around a rotation axis 10 using a first bearing 11 and a second bearing 12. The rotation axis 10 is preferably the longitudinal axis of the impeller 3. Both bearings 11 and 12 are contact-type bearings in this embodiment. However, at least one of the bearings 11 and 12 could 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, to some extent, pivotal movement. A pin 15 is provided that forms one of the bearing surfaces. The second bearing 12 is disposed within a support member 13 for stabilizing the rotation of the impeller 3, and the support member 13 has at least one opening 14 for blood flow. The impeller 3 has blades 31 mounted thereon for transporting 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 blood pump, with the primary direction of flow being axial. It will be appreciated that the blood pump 1 could also be a purely axial blood pump, depending on the configuration of the impeller 3, and in particular the blades 31.

[0037] The blood pump 1 includes an impeller 3 and a drive unit 4. The drive unit 4 includes a plurality 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 rotation axis 10; more specifically, the longitudinal axis of each pillar 40 is parallel to the rotation axis 10. One end 420 of the pillars 40 is disposed adjacent to the impeller. Coil windings 44 are disposed around the pillars 40. The coil windings 44 are sequentially controlled by a control to generate a rotating magnetic field. Part of the control unit is a printed circuit board 6 connected to electrical wires 26. The impeller includes 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 positioned to interact with the rotating magnetic field to cause rotation of the impeller 3 about the rotation axis 10.

[0038] To close the magnetic flux path, a backplate 50 is disposed on the end of the pillar 40 opposite the impeller side of the pillar. The pillar 40 serves 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., 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 the blood flow along the impeller 3. The yoke 37 may also be made of cobalt steel. One or more washout channels extending toward the center bearing 11 may be formed within the yoke 37 or the magnet 32.

[0039] Figure 2 shows a cross-sectional view of a first 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-side ends 420 of the pillars 40 do not extend radially beyond the windings 44. Rather, the cross-section of the pillars 40 is constant in the direction of the longitudinal axis LA of the pillars 40. Thus, the pillars 40 are avoided from coming close to each other, as 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.

[0040] The drive unit according to Fig. 2 may include at least two pillars 40. The number of pillars is preferably a multiple of three, and therefore may be three, nine, or twelve. Alternatively, the number of pillars 40 may be a multiple of two, such as two, four, six, eight, ten, or twelve. A larger number of pillars 40 may also be possible. A number of six pillars 40 is preferred. 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.

[0041] The pillar 40 may be comprised of a discontinuous soft magnetic material that is discontinuous in electrical conductivity, as shown. The discontinuous soft magnetic material includes a plurality of sheets 85 made of a ferromagnetic material that are stacked together. The stacking direction is aligned along the longitudinal axis LA of the pillar 40 and is labeled by the arrow DL. As shown, the pillar 40 is aligned parallel to the axis of rotation 10.

[0042] A spacer 7 is disposed around the pillars 40. It is made of a magnetically inert material and has the purpose of maintaining a constant distance between the pillars 40 at their impeller-side ends 420. The spacer 7 will be described in more detail with respect to FIGS. 6A-6C. The impeller-side ends 424 of the coil windings 44 extend up to the spacer 7. At the other end of the pillars 40, a backplate 50 is provided. According to the embodiment shown in FIG. 2, the backplate 50 has a recess for receiving the pillars 40 therein. More specifically, it includes a first layer 51 having an opening 511 for the rear end 450 of the pillar 40. The backplate 50 will be described in more detail with respect to FIGS. 7A-7C.

[0043] It is conceivable to realize embodiments of the blood pump 1 having any combination of the three above-mentioned features: the impeller-side ends 424 of the pillars not extending radially beyond the impeller-side ends 450 of the windings 44; providing magnetically inactive spacers 7 between the pillars 40; and a backplate 50 having recesses for receiving the rear ends 450 of the pillars 40.

[0044] 3A and 3B show a side view and a perspective view of the magnetic core 400 of the drive unit 4 of the drive unit-impeller arrangement according to FIGS. 1 and 2. The posts 40 and backplate 50 of the magnetic core 400 are shown at a distance to the magnet structure 32 of the impeller 3. As can be seen, the front face 42 of each of the impeller-side ends 420 of the posts 40 is provided with a recess. In this particular embodiment, and in all embodiments described below, the recess extends over the entire front face 42 so that the perimeter of the recess coincides with the perimeter of the front face 42.

[0045] The inclination of the recesses therefore extends around the periphery of the front face 42. When viewed in a cross-sectional plane extending vertically through the front face 42, the recesses have a triangular cross-section, which in the illustrated embodiment is perpendicular to the longitudinal axis of each pillar 40. This would be different in an embodiment in which the front faces 42 of the pillars 40 are each inclined so as to together form a conical front side of the magnetic core 400, as described in WO 2017 / 162619 A1. That is, in WO 2017 / 162619 A1, the pillars each have a shaft and an inclined head portion at the impeller-side end of the shaft. The front faces of these head portions are also inclined, but the front faces are inclined downwards towards the central region of the front face, and may be provided with the above-mentioned inclined triangular cross-section when viewed in a cross-sectional plane extending vertically through the front face.

[0046] The inclination of the front surface 42 in the recess downward toward the central region of the front surface serves to concentrate and thus bunch the magnetic field lines extending through the front surface, as will be explained below with reference to FIG. 4 . However, within the recess, the front surface 42 not only inclines downward toward the central region of the front surface 42, but also inclines downward radially outward relative to the rotation axis 10. In other words, the radially inner region of the front surface 42 in the recess protrudes axially more than the radially outer region of the front surface 42 in the recess. The purpose of the downward radially outward inclination is to direct the magnetic field lines toward the outer periphery of the impeller's magnet structure 32, thereby increasing the lever arm with which the impeller 3 is rotated and therefore increasing the torque. Therefore, the inclination of the recess toward the center of the front surface 42 and also radially outward results in the fact that, for a pillar 40 with a triangular cross section, the recess is open toward the side of the pillar 40 located radially outward relative to the rotation axis. Therefore, the point of maximum depth of the front surface 42 is located at the periphery of each post 40 and can range from 0.05 mm to 0.3 mm, preferably 0.1 mm to 0.2 mm, and most preferably is about 0.2 mm.

[0047] FIG. 4 shows a schematic diagram of the unwound six pillars 40a, 40b of a magnetic core 400, such as the core 400 shown in FIGS. 3A and 3B. To create a rotating magnetic field, two aspects are important. First, some of the pillars must be magnetized in a positive direction, while others are magnetized in a negative direction, so that the magnetic fluid lines of magnetic flux extend from the positively magnetized pillars, through the magnet structure of the impeller 32, into the negatively magnetized pillars, and then through the backplate 50 back into the positively magnetized pillars, thereby creating a closed magnetic field. Second, the magnetization direction of the pillars must be changed sequentially from pillar to pillar in the circumferential direction to rotate the magnet structure 32 of the impeller 3 about the rotation axis 10. To accomplish this, adjacent pillars are magnetized in opposite directions by appropriately directed currents through coil windings 44 around each of the pillars 40. For example, the first pillar can be magnetized positively, the second adjacent pillar negatively, the third adjacent pillar positively, the fourth adjacent pillar negatively again, and so on. However, in a preferred embodiment, there are always two adjacent pillars magnetized in one direction to attract the magnet structure 32 of the impeller 3, and only one of the next subsequent pillars is magnetized in the opposite direction. In the case of six pillars, four pillars 40b are magnetized in one direction and two pillars 40a are magnetized in the opposite direction, as indicated in FIG. 4, which shows a schematic representation of the unwound six pillars. As can be further seen from FIG. 4, the magnetic field lines 500 extending through the recessed front face 42 are focused to form a bundle due to the inclined surfaces within the recess. Therefore, the risk of a short circuit, in the sense of the magnetic field lines 500 bridging between adjacent pillars 40a and 40b, is minimized.

[0048] 5A-5D show side views of the impeller end 420 of the post according to four different embodiments. The embodiment shown in FIG. 5A corresponds to the embodiment described above, having a recess with a perimeter that coincides with the perimeter of the front face, sloping downward toward the central region of the front face 42 and with two sloping side walls 42a that also slope radially outward relative to the axis of rotation, as explained above. As a result, the recess has a triangular cross-section when viewed in any cross-sectional plane extending vertically through the front face 42 and is open radially outward of the post.

[0049] The embodiment shown in Figure 5B substantially corresponds to the embodiment of Figure 5A, except that it has a flat bottom 42b. Therefore, the triangular cross section of the recess is limited radially inward of the post relative to the axis of rotation. Further radially outward, the cross section is trapezoidal. Therefore, the bottom 42b is flat and parallel to the general plane of the front face 42, whereas the side wall 42a is a straight side wall with an oppositely oriented slope.

[0050] In the embodiment shown in FIG. 5C, the recess has curved, sloping sidewalls 42 a such that the slope of the recess is greatest around the periphery of the front surface 42 .

[0051] The embodiment shown in Figure 5D is a combination of the embodiments shown in Figures 5B and 5C, i.e., the recess has a flat bottom 42b and curved, sloping sidewalls 42a.

[0052] 6A-6C show perspective, front, and side views of the spacer 7, respectively. The spacer 7 generally has the shape of a disk or wheel with a central through-hole 75. The spacer 7 includes an opening 71 for each of the posts. For an embodiment with six posts 40, six openings 71 are present, as shown. Spaced-apart spokes 72 are positioned between the openings 71. When the posts 40 are inserted into the openings 71, the spaced-apart spokes 72 maintain a constant distance between the posts 40. The spacer 7 further includes outer and inner rims 73 and 74 that connect adjacent spaced-apart spokes 72 and stabilize the spacer. The spacer 7 is made of titanium, a paramagnetic material that avoids magnetic short circuits when placed between the impeller-side ends 420 of the posts 40. Titanium provides high mechanical strength, allowing for the fabrication of a spacer 7 with a small thickness, which is advantageous in terms of construction space consumption. Titanium also has low electrical conductivity, minimizing eddy current losses, and is easy to machine. However, any other non-magnetic material can be used as well, provided that it is stable, can be machined with high precision, and does not readily conduct electricity. The use of diamagnetic materials is also possible, as they will cancel out external magnetic fields.

[0053] FIG. 7A shows a perspective view of the first layer 51 of the backplate 50. The first layer 51 has the general shape of a disk or wheel with a central hole 515. The first layer 52 includes openings 511 in which the rear ends 450 of the posts 40 are positioned. The first layer 51 includes spaced-apart spokes 512 between the openings 511. One purpose of the spaced-apart spokes 512 is to maintain a constant distance between the rear ends 450 of the posts 40. The first layer 51 also includes outer and inner rims 513 and 514 that connect the spaced-apart spokes 512 at the outer and inner radial ends of the openings 511, respectively. The first layer 51 may be made of a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity. It may include several ferromagnetic sheets 85, specifically, three sheets as shown in FIG. 7A. The sheets 85 are laminated together using an electrically non-conductive material to form the discontinuous soft magnetic material. The stacking direction DL is generally parallel to the sheets 85, the direction of their main extent defining the stacking plane. Within the backplate 50, the sheets 85 are perpendicular to the axis of rotation 10. In the center of the first layer 51, a hole 515 is arranged, which has the purpose of facilitating the assembly of the first layer 51 and the second layer 52, for example, it may serve to center the first and second layers 51, 52.

[0054] FIG. 7B shows a perspective view of the second layer 52 of the backplate 50. The second layer 52 has substantially the form of a disk with a hole 525 in its center corresponding to the hole 515 in the first layer 51. The second layer 52 does not have any openings for the rear ends of the posts 40. Instead, the second layer 52 provides a contact plane 526 facing the rear ends 450 of the posts 40. The rear ends 450 of the posts are in contact with the contact plane 526 of the second layer 52 of the backplate 50 in the assembled state of the drive unit, transmitting magnetic flux between the rear ends 450 of the posts 40 and the backplate 50. Because the entire rear ends 450 of the posts 40 are in contact with the contact plane 526, magnetic flux can be exchanged between the posts 40, and a magnetic null point can be created in the second layer 52. To enable this, the second layer 52 is made of a soft magnetic material. The soft magnetic material may be a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity and may include stacked sheets 85 similar to the structure described above for the first layer 51. As an example, three sheets 85 may form the second layer 52, as shown in FIG. 7B . Within the second layer 52, the stacking direction D is perpendicular to the rotation axis 10. The sheets 85 are ferromagnetic and electrically conductive, whereas the intermediate layers between the sheets 85, not explicitly shown, are non-ferromagnetic and electrically non-conductive. This type of discontinuous soft magnetic material reduces eddy currents that would otherwise be generated in greater amounts by changes in magnetic flux. The hole 525 in the center of the second layer 52 facilitates assembly of the first layer 51 and the second layer 52; for example, it may serve to center the first and second layers 51, 52.

[0055] FIG. 7C shows a cross section of the backplate 50. It is composed of a first layer 51 and a second layer 52 bonded together at their major surfaces with the largest extent. The bond between the first layer 51 and the second layer 52 of the backplate 50 can be established in the same manner as between the sheets 85 of the first and second layers 51, 52. The through-holes 515 and 525 of the first layer 51 and the second layer 52 are aligned with each other to center the first and second layers 51, 52. By stacking the first and second layers 51, 52, the opening 511 is closed at one end by the second layer 52, thereby forming a recess 501 for receiving the rear end 450 of the post 40. The bottom of the recess 501 forms a contact plane 526. When the post 40 is inserted into the recess 501, the rear end 450 contacts the contact plane 526. Furthermore, the positions of the pillars 40 are fixed by the spaced spokes 512 and by the outer and inner rims 513, 514, which together surround each pillar 40. Thus, a magnetic connection is established between the second layer 52 and the rear end surface 45 of the pillar 40 at the contact plane 526, and a second magnetic connection is also established between the pillar 40 and the aforementioned surrounding portion of the first layer 51. However, the main part of the magnetic flux is transmitted through the contact plane 526. Preferably, both the surface at the rear end 450 of the pillar 40 and the contact plane 526 have a predetermined flatness. In this way, the gap between the surface 45 at the rear end 450 of the pillar 40 and the contact plane 526 can be maintained below a specific value, preferably less than 10 μm. This improves the transmission of magnetic flux between the pillar 40 and the backplate 50. Preferably, no additional material is present between the surface 45 at the rear end 450 of the pillar 40 and the contact plane 526. In this embodiment of the invention, the transmission of magnetic flux through surface 45 and backplate 50 is independent of the manner in which posts 40 are fastened to backplate 50 .

[0056] 8A to 8D show the preparatory steps for the production of the pillars 40. Fig. 8A shows a perspective view of a plate 8, hereinafter also called workpiece, made of a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity.

[0057] In Figure 8A, plate 8 is marked with a width W for cutting workpiece bar 81 from plate 8. The width W of workpiece bar 81 is identical to the length of column 40 that will be produced from workpiece bar 81. Figure 8B shows an enlarged view of the area marked by rectangle R in Figure 8A. Here, stacked sheets 85 of discontinuous soft magnetic material are visible. The stacking direction DL extends along the main plane of plate 8 and therefore forms the stacking plane.

[0058] Figure 8C shows workpiece bar 81 cut as a discrete piece of material from plate 8. Figure 8D shows an enlarged view of the portion labeled by rectangle R in Figure 8C. Sheet 85 of workpiece bar 81 is visible in this view.

[0059] 9A shows the workpiece bar 81 of FIGS. 8C and 8D, which forms the basis for the welding step in preparation for cutting out the pillars 40 from the bar 81. On the side of the bar 81 facing left in FIG. 9A, a number of cross sections 84 of the pillars 40 to be produced from the bar 81 are shown. The pillars 40 are produced by cutting out these cross sections 84 from the bar 81. Since the width W of the bar 81 corresponds to the length of the pillar 40, the side surfaces 811 and 812 of the bar 81 become the end faces of the impeller end 420 and the rear end 450 of the pillar 40.

[0060] FIG. 9B shows the next preparatory step before cutting out the pillars 40. Two weld seams 82 and 83 are welded on the face 811 of the bar 81, spaced apart from each other and across each cross section 84 of the pillars 40 to be cut out. The weld seams 82 and 83 extend perpendicular to the lamination direction DL of the sheets 85. In this way, the discontinuous sheets of material are connected to each other. Instead of two weld seams, a single weld seam can be provided. In addition, a similar weld seam can be provided on the opposite side 812 of the bar 81. The sheets 85 have a better mechanical connection to each other thanks to the weld seams 82 and 83, and are also electrically connected. This has the advantage that current can flow from any location on the discontinuous soft-magnetic material destined for the pillars 40 to each location of the electrical connection on the bar 81 that may be required, for example, for electrical discharge machining. In this way, electrical discharge machining is significantly facilitated. Furthermore, since the cut-out pillars 40 cannot delaminate, higher process reliability is achieved. Preferably, laser welding is applied. It may be advantageous to apply the welding power twice or even multiple times to the same weld. In Figure 9C, a portion of the bar 81 marked by the rectangle R is shown enlarged.

[0061] Thus, FIG. 9C shows a number of cross sections 84 of the posts 40 to be cut from the bar stock 81. The cross sections 84 have a substantially triangular shape. As shown, the corners may be rounded. The convex side 842 of the triangle shown on the left side of the cross section 84 in FIG. 9C has a convex shape. This type of cross section 84 is advantageous for fully utilizing the available construction space inside the cylindrical pump housing 2. The bisector of the corner 841 of the cross section 84 opposite the convex side 842 of the cross section 84 is aligned with the stacking direction DL. In this way, the sheet 85 extends symmetrically through the cross section 84.

[0062] FIG. 10 shows a post 40 cut from bar stock 81. As can be seen, weld seams 82 and 83 are still present on surface 45 at rear end 450 of bar stock 81. Post 40 has a constant cross-section 84 along its entire length. If needed, weld seams 82 and 83 can be deburred after post 40 is cut. Simultaneously, or in a subsequent step, a recess having a structure as shown in any of FIGS. 5A-5D or a different structure is cut into the surface at the opposite end of post 40, which will later form front surface 42 of impeller end 420 of post 40. Alternatively, the recess can be provided with a weld and formed before post 40 is cut from bar stock 81, such as by wire electrical discharge machining.

[0063] FIG. 11 shows another configuration of two cross sections 84 on a side surface 811 of a workpiece bar 81. In contrast to the workpiece bar 81 shown in FIGS. 9A-9C, the side surface 811 of the workpiece bar 81 in FIG. 11 has a size that allows two cross sections 84 to be arranged next to each other in a direction perpendicular to the stacking direction DL. The cross sections 84 are oriented with respect to the stacking direction DL so that the bisector B of each of the cross sections 84 opposite its respective convex side 842 is aligned with the stacking direction DL. This arrangement of the cross sections 84 along the bar 81 conserves material; less waste material is generated. Depending on the thickness of the bar 81 and the required cross-sectional dimensions of the column 40, it is conceivable to stack even more cross sections 84 of the column 40 in a direction perpendicular to the stacking direction DL.

[0064] Each of the weld seams 82 and 83 extends across each of the cross sections 84. The weld seams 82, 83 extend across the entire side surface 811 of the bar 81 in a direction perpendicular to the lamination direction DL. In this way, all of the discontinuous sheets 85 of soft magnetic material of the bar 81 are connected to one another.

[0065] 12 shows an example of a column 40 cut from welded bar stock 81, i.e., a front view on the rear end face 45 of the column 40. As shown in FIG. 12, a single weld seam 86 of substantial width, which may cover more than about one-third of the height of the triangular cross section 84, extends along the convex side 842 of the cross section 84. The weld seam 86 extends perpendicular to the stacking direction DL to connect all of its sheets. However, two weld seams, as shown in FIG. 11, are preferred over a single seam. Again, the bisector B of the corner 841 opposite the convex side 842 is aligned with the stacking direction DL.

[0066] 13 shows a second embodiment of a drive unit-impeller arrangement for the blood pump 1 according to FIG. 1. Similar to the first embodiment shown in FIG. 2, the front face 42 of the impeller end 420 has a recess that tapers radially outward away from the magnetic structure 32 of the impeller 3. In addition, 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 prevented from coming close to each other, as this would cause a partial magnetic short circuit and therefore reduce the power of the electric motor of the blood pump.

[0067] Again, the drive unit according to Fig. 13 may include at least two pillars 40. The number of pillars is preferably a multiple of three, and therefore may be three, nine, or twelve. Alternatively, the number of pillars may be a multiple of two, such as two, four, six, eight, ten, or twelve. A greater number of pillars 40 may also be possible. A number of six pillars 40 is preferred. 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.

[0068] This second embodiment differs from the first embodiment shown in FIG. 2 by a different structure of the magnetic core. Here, the magnetic core 400 includes the magnetic components of the drive unit 4, namely the post 40 and the backplate 50, in one single part or monoblock. The monoblock consists of a discontinuous soft magnetic material, which is discontinuous in terms of electrical conductivity. As shown, it includes multiple sheets 85 of ferromagnetic material stacked on top of each other to form the monoblock 9 as shown in FIG. 14C. The stacking direction DL is parallel to the axis of rotation 10.

[0069] The coil winding 44 extends to the impeller end 420 of the pillar 40. This has the advantage that magnetomotive force 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 that protrudes radially away from the pillar 40. This protrusion 401 forms a stop for the coil winding 44 toward the backplate 50. The integrated magnetic core 400 connects the backplate 50 and the pillar 40 with high rigidity, so that spacers between the pillars 40 at the impeller end 420 of the pillars can be omitted. The integrated magnetic core 400 has the advantage that an optimal magnetic connection between the pillar 40 and the backplate 50 is achieved. The magnetic core 400 can have a diameter of less than 10 mm.

[0070] 14A-14C illustrate steps for fabricating a magnetic core 400 for a drive unit 4 of the drive unit-impeller configuration as shown in FIG. 13. FIG. 14A shows 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 discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity. It includes sheets 85 oriented in a stacking direction DL that extends along the major planes of the sheets 85. The sheets 85 are each joined to their respective adjacent sheets by a joining layer of electrically non-conductive material, not explicitly shown in FIGS. 14A-14C.

[0071] 14B shows the magnetic core 400 in a semi-finished state, where it has been machined from the cubic monoblock 9 into a substantially cylindrical body 94. During this machining step, the protrusions 401 are produced. The reduced diameter sections 404 of the body 94, which form the peripheral surfaces of the pillars 40 of the magnetic core 400, are produced to have a diameter corresponding to the outer radius of the outermost convex side surfaces 842 of the pillars 40.

[0072] Next, the body 94 is further fabricated to produce the magnetic core 400 as shown in FIG. 14C. For this production step, electrical discharge machining can be used. For example, wire-cut electrical discharge machining can be applied to produce the slots 49 that separate the posts 40 from each other. Inside the slots, space is provided for the coil windings 44. At the bottom of the slots 49, an intermediate section 59 of the integral backplate 50 extends between the rear ends of the posts 40. The intermediate section 59 is integral with the posts 40 and the backplate 50. The entire magnetic core 400 is therefore formed by a monoblock 9.

[0073] The lamination direction DL in the magnetic core 400 is such that it is 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 fabricate the magnetic core 400 from coiled soft magnetic sheet material separated by electrically non-conductive layers. In this case, the lamination direction DL in the base plate 50 is always circumferential, which is advantageous for avoiding eddy currents in the magnetic flux in the base plate 50.

[0074] 15A-15C show how one or more welds can be provided on the surface of the integrated magnetic core as produced according to FIGS. 14A-14C. 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 each other and across the cross section of the body 94 to be cut out of the monoblock 9. The weld seams 82, 83 extend perpendicular to the stacking direction DL of the sheets 85. In this way, discontinuous sheets of soft magnetic material are connected to each other. Instead of three weld seams, more weld seams or a single, wider 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 one another due to 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 each position of an electrical connection in the body 94 that may be needed, 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 from the body 94 cannot delaminate. Preferably, laser welding is applied. It may be advantageous to apply the welding power twice or even multiple times to the same weld.

[0075] The body 94 is then machined to form the magnetic core 400 as shown in Figure 15C. In this second embodiment, the recesses in the front face 42 of the post 40 have three sloping sidewalls instead of two, all of which slope downward toward the center of the front face. The periphery of the recesses coincides with the periphery of the front face 42 of the post 40. However, the recesses do not open to either side of the post 40. In particular, the embodiment as shown in Figure 14C, which has only two sloping sidewalls, is more effective and therefore preferred.

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) rotatably disposed within the pump casing (2) about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey blood from the blood inlet (21) to the blood outlet (22); a drive unit (4) for rotating the impeller (3), the drive unit (4) including a plurality of pillars (40) arranged around the rotation axis (10), each of the pillars (40) having an impeller-side end (420) facing the impeller (3) with a front surface (42) facing the impeller (3); a coil winding (44) disposed around each of the pillars (40) to create magnetic field lines (500) extending through the front surface (42) of each of the pillars (40), the coil winding (44) being controllable to create a rotating magnetic field; Equipped with the impeller (3) includes a magnet structure (32) arranged to interact with the rotating magnetic field to cause rotation of the impeller (3); the front surface (42) of at least one of the posts (40) includes a recess sloping downwardly toward a central area of ​​the front surface (42) such that the front surface (42) focuses at least a portion of the magnetic field lines (500) extending through the front surface (42); An intravascular blood pump (1) characterized in that the recess has a flat bottom (42b).

2. 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) rotatably disposed within the pump casing (2) about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey blood from the blood inlet (21) to the blood outlet (22); a drive unit (4) for rotating the impeller (3), the drive unit (4) including a plurality of pillars (40) arranged around the rotation axis (10), each of the pillars (40) having an impeller-side end (420) facing the impeller (3) with a front surface (42) facing the impeller (3); a coil winding (44) disposed around each of the pillars (40) to create magnetic field lines (500) extending through the front surface (42) of each of the pillars (40), the coil winding (44) being controllable to create a rotating magnetic field; Equipped with the impeller (3) includes a magnet structure (32) arranged to interact with the rotating magnetic field to cause rotation of the impeller (3); the front surface (42) of at least one of the posts (40) includes a recess sloping downwardly toward a central area of ​​the front surface (42) such that the front surface (42) focuses at least a portion of the magnetic field lines (500) extending through the front surface (42); An intravascular blood pump (1) characterized in that said recess has a triangular cross section when viewed in a cross-sectional plane extending vertically through said front surface (42).

3. 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) rotatably disposed within the pump casing (2) about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey blood from the blood inlet (21) to the blood outlet (22); a drive unit (4) for rotating the impeller (3), the drive unit (4) including a plurality of pillars (40) arranged around the rotation axis (10), each of the pillars (40) having an impeller-side end (420) facing the impeller (3) with a front surface (42) facing the impeller (3); a coil winding (44) disposed around each of the pillars (40) to create magnetic field lines (500) extending through the front surface (42) of each of the pillars (40), the coil winding (44) being controllable to create a rotating magnetic field; Equipped with the impeller (3) includes a magnet structure (32) arranged to interact with the rotating magnetic field to cause rotation of the impeller (3); the front surface (42) of at least one of the posts (40) includes a recess sloping downwardly toward a central area of ​​the front surface (42) such that the front surface (42) focuses at least a portion of the magnetic field lines (500) extending through the front surface (42); The intravascular blood pump (1) is characterized in that the recess has no wall and is therefore open toward a first side surface of the at least one of the pillars (40), the first side surface being located radially outward relative to the rotation axis (10).

4. 4. An intravascular blood pump (1) according to any one of claims 1 to 3, characterized in that the recess extends around the periphery of the front surface (42).

5. 5. An intravascular blood pump (1) according to claim 4, characterized in that the recesses extend to the periphery of the front surface (42) on at least two sides of the front surface that are closest to adjacent ones of the plurality of pillars (40), or on exactly two sides of the front surface that are closest to adjacent ones of the plurality of pillars (40).

6. 6. An intravascular blood pump (1) according to claim 4 or 5, characterized in that the periphery of the recess coincides with the periphery of the front surface (42).

7. An intravascular blood pump (1) according to any one of claims 2 to 6, characterized in that the recess has a flat bottom (42b).

8. 8. An intravascular blood pump (1) according to claim 1 or 7, characterized in that the recess has a linear, inclined side wall (42a) when viewed in a cross-sectional plane extending vertically through the front surface (42).

9. 8. An intravascular blood pump (1) according to claim 1 or 7, characterized in that the recess has a curved, inclined side wall (42a) when viewed in a cross-sectional plane extending vertically through the front surface (42).

10. 7. An intravascular blood pump (1) according to any one of claims 2 to 6, characterized in that the recess has a curved cross-section with a curved bottom when viewed in a cross-sectional plane extending vertically through the front surface (42).

11. 7. An intravascular blood pump (1) according to any one of claims 2 to 6, characterized in that the recess has a triangular cross section when viewed in a cross-sectional plane extending vertically through the front surface (42).

12. 12. An intravascular blood pump (1) according to any one of claims 1 to 11, characterized in that within the recess, the front surface (42) is inclined downward in a radially outward direction relative to the rotation axis (10), so that a radially inner region of the front surface (42) within the recess protrudes axially beyond a radially outer region of the front surface (42) within the recess.

13. 13. An intravascular blood pump (1) according to any one of claims 1, 2 or 4 to 12, characterized in that the recess has no wall and is therefore open towards a first side of the at least one of the posts (40), the first side being located radially outward relative to the axis of rotation (10).

14. 14. An intravascular blood pump (1) according to claim 3 or 13, characterized in that the at least one of the pillars (40) has a triangular cross section having three sides including the first side, the first side being located radially outward with respect to the axis of rotation (10) compared to the other two of the three sides.

15. An intravascular blood pump (1) according to any one of claims 1 to 14, characterized in that the recesses have a maximum depth of 0.05 mm to 0.3 mm.

16. 16. An intravascular blood pump (1) according to any one of claims 1 to 15, characterized in that the at least one of the pillars (40) has a longitudinal axis (LA) and its impeller-side end (420) does not extend radially beyond the impeller-side end (424) of the coil winding (44) disposed around the at least one of the pillars (40), wherein the term "radially" relates to a direction transverse to the longitudinal axis (LA).

17. 17. An intravascular blood pump (1) according to any one of claims 1 to 16, characterized in that at least one of the pillars comprises or consists of a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity in a cross section transverse to the longitudinal axis (LA) of the respective pillar (40).

18. 18. An intravascular blood pump (1) according to claim 17, characterized in that at least one weld (82, 83, 86) is provided on a surface (811) of the discontinuous soft magnetic material, and the weld (82, 83, 86) bridges at least one discontinuity in electrical conductivity within the discontinuous soft magnetic material.

19. 19. An intravascular blood pump (1) according to any one of claims 1 to 18, characterized in that each of the pillars (40) has a rear end (450), the drive unit (4) includes a backplate (50) connecting the rear ends (450) of the pillars (40) and extending between the pillars (40) in an intermediate section (59), and the material of at least one of the pillars (40) is integral with the material of the intermediate section (59) of the backplate (50).

20. 19. An intravascular blood pump (1) according to any one of claims 1 to 18, characterized in that each of the columns (40) has a rear end (450), the drive unit (4) includes a backplate (50) connecting the rear ends (450) of the columns (40), and at least one of the rear ends (450) of the columns (40) has a rear end surface (45) in contact with the backplate (50).

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