Blood pump

Abstract

The present invention relates to an intravascular blood pump for percutaneous insertion into a blood vessel of a patient. The blood pump includes a pump housing having a blood flow inlet and a blood flow outlet and an impeller disposed in the pump housing to be rotatable about a rotation axis. The impeller has blades sized and shaped for delivering blood from the blood flow inlet to the blood flow outlet. The blood pump includes a drive unit for rotating an impeller, which includes a plurality of posts arranged about an axis of rotation. Each of the posts has an impeller-side end directed toward the impeller, the impeller-side end having a front surface facing the impeller. A coil winding is disposed around each of the posts to generate magnetic field lines through a front surface of each post and is controllable to generate a rotating magnetic field, the impeller comprising a magnetic structure arranged to interact with the rotating magnetic field to cause the impeller to rotate. The front surface of the at least one post includes a concave surface in which the front surface is inclined downward toward a central region of the front surface to concentrate at least part of the magnetic field lines passing through the front surface.

Description

[0001] Divisional application

[0002] This application is a divisional application of the patent application with the international application date of September 1, 2020, application number 202080061726.X, the date of entering the Chinese national phase on March 2, 2022, and the invention name being "Blood Pump". Technical Field

[0003] The present invention relates to an intravascular blood pump, in particular to an intravascular blood pump for percutaneously inserting into a patient's blood vessel to support blood flow in the patient's blood vessel. The blood pump has an improved driving unit. Background Art

[0004] Different types of blood pumps are known, such as axial-flow blood pumps, centrifugal (i.e., radial) blood pumps, or hybrid blood pumps in which blood flow is induced by both axial and radial forces. An intravascular blood pump is inserted into a patient's blood vessel, such as the aorta, by means of a catheter. A blood pump typically comprises a pump housing having a blood flow inlet and a blood flow outlet connected by a passageway. To induce blood flow along the passageway from the blood flow inlet to the blood flow outlet, an impeller or rotor is rotatably supported within the pump housing, wherein the impeller is provided with blades for conveying blood.

[0005] A blood pump is typically driven by a drive unit, which may be an electric motor. For example, WO 2017 / 162619A1 discloses an intravascular blood pump having an impeller magnetically coupled to an electric motor. The impeller includes a magnet arranged adjacent to an electromagnetic region in the electric motor. Due to the attractive force between the magnets in the impeller and the electromagnetic region in the electric motor, the rotation of the electric motor is transmitted to the impeller. Specifically, the drive unit includes a plurality of stator poles arranged around the rotation axis of the impeller, and each pole carries a coil winding and serves as a magnetic core. A control unit sequentially supplies voltage to the coil winding to generate a rotating magnetic field, which causes the magnetically coupled impeller to rotate.

[0006] More specifically, the intravascular blood pump in WO 2017 / 162619 Al comprises a pump housing having a blood flow inlet and a blood flow outlet, an impeller, and a drive unit for rotating the impeller. By rotation of the impeller within the pump housing about an axis of rotation, blood can be transported from the blood flow inlet to the blood flow outlet by the blades of the impeller. The drive unit comprises six posts and a back plate connecting the back ends of the posts for use as a magnetic yoke. The posts are arranged in a circle around the axis of rotation, as seen in a plane perpendicular to the axis of rotation, with each post having a longitudinal axis parallel to said axis of rotation. Each post has a stem portion and a head portion inclined at the end of the stem portion pointing towards the impeller side of the impeller, which head portion extends radially beyond the stem portion to form a shoulder, which can serve as an axial stop for a coil winding arranged around each post. A control unit supplies voltages to the coil windings in turn to generate a rotating magnetic field. The impeller comprises a magnetic structure arranged to interact with the rotating magnetic field, thereby causing the impeller to follow its rotation.

[0007] In operation, adjacent posts can have different magnetization. As a result, magnetic flux passing through the posts tends to flow between those adjacent posts and away from the impeller. Such magnetic flux is lost for producing torque. A disadvantage of the prior art is that the distance between the head portions extending radially beyond the stem portions is particularly small. As a result, there is a considerable parasitic magnetic flux between the head portions, which is lost for producing torque. While this parasitic flux can be counteracted by placing a magnetic insulation material such as a magnet between the head portions, the available space will be very limited and the polarization of the magnet will have to be changed periodically for a reasonable insulation, which is difficult. It is an object of the present invention to improve the drive unit in this respect. SUMMARY

[0008] The blood pump of the present invention can correspond to the blood pump described above. It can thus be an axial blood pump or a diagonal blood pump (pure centrifugal blood pumps are typically too large in diameter for intravascular applications) which pumps partly axially and partly radially. According to one aspect of the present invention, however, the front surface of the impeller side end of at least one of the posts, preferably of each of the posts, comprises a concave surface in which the front surface slopes downwardly towards a central region of the front surface to concentrate at least part of the magnetic field lines passing through the front surface.

[0009] The magnetic field lines of the magnetic flux flowing out of and into the surface of a component made of a magnetic material extend perpendicular to the surface, i.e. they flow out of and into the surface plane perpendicularly. By providing the front surface of the posts with a concave surface, i.e. a depression with a region in which the front surface slopes downwardly towards the center of the front surface, the magnetic field lines entering and leaving the post through the front surface are forced to extend closer to the central axis of the post. Since the magnetic field lines never cross each other, as a result they are concentrated in the front of the impeller side end of the post and point as a bundle towards the impeller. The parasitic flux between adjacent posts is thus reduced.

[0010] The inclination of the concave surface is less than 90° with respect to the surface plane, preferably between 0° and 30°.

[0011] Preferably, the concave surface extends to the outer periphery of the front surface. In other words, the concave surface can start from the outer border of the front surface. This has the effect that also the outermost magnetic field lines are influenced by the inclination of the concave surface. The outermost magnetic field lines are those which tend to join the adjacent column most. Therefore, if the concave surface extends to the outer periphery of the front surface of the column, the concave surface is most effective.

[0012] It can be sufficient that the concave surface extends to the outer periphery of the front surface of the column on at least two, preferably exactly two opposite sides of the front surface, i.e. on those sides which are closest to the adjacent column. This can be advantageous, in particular when the columns are for example cylindrical, so that the cross section is circular. That is, the danger of magnetic field lines joining the adjacent column is greatest in the case of columns which have almost no distance from each other. Therefore, if the concave surface extends to the outer periphery of the front surface of the column only on the two sides which are located closest to the respective adjacent column, this concave surface is sufficient.

[0013] However, it is preferred that the outer periphery of the concave surface coincides with the outer periphery of the front surface. In this way, due to the inclination of the concave surface, the outermost magnetic field lines point towards the center of the front surface along the entire outer periphery of the front surface. As mentioned before, the outermost magnetic field lines are those which are most likely to avoid the impeller and turn aside. Therefore, if the outer periphery of the concave surface coincides with the outer periphery of the front surface, this concave surface is most effective.

[0014] The concave surface can have a straight bottom, because it can be sufficient to direct the outermost magnetic field lines towards the center. Therefore, at least one region of the outer periphery of the concave surface is inclined downwards. In this case, the concave surface can have straight inclined side walls when viewed in a sectional plane which is vertical through the front surface, or the concave surface can have curved inclined side walls when viewed in a sectional plane which is vertical through the front surface. Curved inclined side walls with an inclination which increases towards the outer periphery of the concave surface have the effect of maximizing the bunching effect of the outermost magnetic field lines.

[0015] Alternatively, the concave surface can have a curved cross section with a curved bottom instead of a straight bottom when viewed in a sectional plane which is vertical through the front surface. In this way, the concentrating effect on the magnetic field lines decreases gradually from the outer periphery towards the center of the concave surface.

[0016] Alternatively, the concave surface can have a triangular cross-section when viewed in a cross-sectional plane passing vertically through the front surface. This increases the maximum depth of the concave surface. The deeper the concave surface, the greater the distance between the corresponding portion of the front surface of the post and the magnetic structure of the impeller, resulting in a reduction in the axial magnetic force generated between the post and the impeller. In particular, by reducing the axial magnetic force, the ratio between magnetic torque and axial magnetic force can be increased, an important metric in the development of magnetically driven intravascular blood pumps. This ratio is important because the amount of magnetic flux that can be generated is generally limited, and therefore it is desirable to use as much of it as possible to generate torque. The technical effect of the concave surface is to reduce the axial force acting on the rotor in the axial direction without sacrificing motor power, or, in other words, to increase motor power for the same total magnetic flux.

[0017] According to a preferred aspect of the present invention, this ratio can be further increased by sloping the front surface within the concave surface downwardly in a radially outward direction (in addition to sloping downwardly toward its central region). Thus, the radially inner region of the front surface within the concave surface protrudes axially relative to the axis of rotation than the radially outer region of the front surface within the concave surface. This also results in an increase in the maximum depth of the concave surface. As previously mentioned, the deeper the concave surface, the greater the distance between the corresponding portion of the front surface of the post and the magnetic structure of the impeller, resulting in a reduction in the axial magnetic force generated between the post and the impeller. Therefore, by sloping the front surface within the concave surface downwardly in a radially outward direction, the ratio between the magnetic torque and the axial magnetic force can be further increased.

[0018] Another important effect achieved by the radially outward downward tilt of the front surface, compared to a horizontal front surface, is that the bundle of concentrated magnetic field lines points radially outward, thus also affecting the magnetic structure of the impeller. This has a positive effect on the achievable magnetic torque. Similarly, this results in an improvement in the ratio between magnetic torque and axial magnetic force. Thus, the positive effect of the radially outward downward tilt of the front surface within the concave surface on the ratio between magnetic torque and axial magnetic force is twofold.

[0019] According to a preferred embodiment of the present invention, the combination of the inclination of the front surface of the concave surface in both the central and radially outward directions results in the concave surface opening toward a side surface of the post, i.e., toward a side surface radially outward relative to the axis of rotation. Preferably, the post has a triangular cross-section with three side surfaces, one of which is radially outward relative to the axis of rotation compared to the other two side surfaces. In this case, the concave surface opens toward the side surface radially outward of the post.

[0020] In all the aforementioned variants, the maximum depth of the concavity may preferably be between 0.05 mm and 0.3 mm.

[0021] According to another aspect of the invention, the impeller-side ends of the pillars do not extend radially beyond the impeller-side ends of the respective coil windings arranged around the pillars, wherein the term "radially" relates 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 distinct head portion. Instead, the pillars preferably have a constant cross-section, at least in the region of their impeller-side ends, and more preferably along their entire length.

[0022] The advantage of the poles without head sections is that the magnetic losses due to parasitic fluxes between adjacent poles are reduced due to the greater distance between the poles. Compared to the pump described in WO 2017 / 162619 A1, in which the impeller-side ends of the poles radially extend beyond the impeller-side ends of the corresponding coil windings, the result is also an increase in the ratio between the achievable magnetic torque and the axial magnetic force between the drive unit and the impeller.

[0023] According to another aspect of the invention, the columns may each comprise a soft magnetic material which is discontinuous in a cross section transverse to, preferably perpendicular to, the longitudinal axis of the respective column, said axis preferably being parallel to the axis of rotation, as described in further detail in WO 2019 / 057636A1. "Discontinuous" in the sense of the present invention means that when viewed in any cross section transverse to the longitudinal axis, the soft magnetic material is interrupted, separated, crossed, etc. by insulating or other material or gaps to form strictly separated areas of soft magnetic material or areas which are interrupted but connected at different locations. In other words, the soft magnetic material of the column is discontinuous in a cross section transverse to, preferably perpendicular to, the direction of the magnetic flux caused by the respective coil windings in the column. Providing discontinuous soft magnetic material in a cross-sectional plane transverse to the direction of the magnetic flux reduces eddy currents. This further improves the effectiveness of the intravascular blood pump.

[0024] Preferably, at least one weld is provided at the surface of the discontinuous soft magnetic material, which welds at least one discontinuity in the discontinuous soft magnetic material in terms of electrical conductivity. The welds enable the magnetic core or a part thereof to be easily manufactured from the discontinuous soft magnetic material. That is, when separating the magnetic core or a leg for the magnetic core from a larger workpiece of discontinuous soft magnetic material, the discontinuous soft magnetic material can delaminate or otherwise lose its integrity due to machining forces exerted on the workpiece during the separation process. This is particularly critical due to the very small dimensions of the magnetic core, in particular the legs of the magnetic core, and can even occur when electrical discharge machining, in particular electrical discharge machining by wire cutting, is used to separate the magnetic core or the leg of the magnetic core out of the workpiece. By virtue of the welds applied to the workpiece prior to the separation step, the mechanical stability of the discontinuous material is improved. In the case of electrical discharge machining for cutting the magnetic core or the leg of the magnetic core out of the workpiece, the flow of electrical current to the cutting site is also improved. The weld or the welds can then form part of the magnetic core or the leg. In particular, the impeller-side end surface of the leg oriented transversely to the rotational axis exposes the discontinuous material. The weld or the welds can therefore be arranged on the impeller-side surface of the leg.

[0025] The drive unit can comprise a back plate connecting the rear ends of the legs. Like the legs, the back plate can comprise discontinuous soft magnetic material. As the magnetic flux in the back plate is essentially transverse or perpendicular to the rotational axis, the soft magnetic material of the back plate can be made discontinuous in a cross section parallel to the rotational axis. Alternatively, the legs and the back plate can be made from a single piece of discontinuous soft magnetic material, such that the soft magnetic material of the back plate and the discontinuous soft magnetic material of the legs are discontinuous in the same direction, preferably in a cross section perpendicular to the rotational axis. In addition to this, essentially all features and explanations described above with respect to the discontinuous material of the legs also apply to the back plate. However, the back plate can also optionally be made from continuous, i.e. solid, soft magnetic material.

[0026] According to one preferred embodiment of the drive unit comprising a back plate connecting the rear ends of the legs, the material of at least one of the legs is integral with the material of an intermediate region of the back plate, wherein the intermediate region of the back plate is the region of the back plate located between the legs. Preferably, all of the legs are integrally connected to the back plate in this way. In other words, at least one of the legs and the back plate, preferably the entire magnetic core of the drive unit, can be made from a single piece of material, which can also be referred to as a single piece. This has the advantage that the magnetic reluctance at the transition between the legs and the back plate can be minimized, thereby improving the magnetic flux. Furthermore, the transition between the legs and the back plate can achieve good mechanical stiffness.

[0027] According to another preferred embodiment of the drive unit comprising a back plate of the rear ends of the connecting columns, at least one column, preferably all columns, are in contact with the back plate with the rear end portion surface of the respective column. Such an advantage is that the quality of the magnetic connection between the columns and the back plate can be independent of the quality of the mechanical connection of the columns and the back plate. For example, the columns can be mechanically fixed in a respective recess in the back plate or fixed by a glue provided around the rear end of the column. Thus, a good magnetic connection can be achieved directly through the rear end portion surface of the column into the back plate, thereby achieving a good magnetic flux without being forced to accept limitations regarding the mechanical performance of the mechanical connection between the columns and the back plate. Furthermore, in case the rear end of the column is received in a properly dimensioned recess in the back plate, a magnetic path for the transfer of the magnetic flux is established, which can exist in addition to the circumferential transfer of the magnetic flux.

[0028] Thus, in this case, the columns can be magnetically connected with the back plate at a respective contact plane of the back plate. The contact plane is preferably arranged parallel to the rear end portion surface of the column. The contact plane is preferably arranged perpendicular to the rotation axis. Preferably, the entire surface area of the rear end portion surface of the column is in contact with the back plate. This significantly reduces the magnetic resistance of the connection between the column and the back plate. The unevenness of the contact plane of the back plate and the rear end portion surface is best such that the resulting gap does not exceed 10 pm.

[0029] The back plate, like the columns, is preferably made of a soft magnetic material, such as electrical steel (magnetic steel) or other suitable material for closing a magnetic flux loop, preferably cobalt steel. The diameter of the back plate can be in the range of 3 mm to 9 mm, such as 5 mm or 6 mm to 7 mm. The thickness of the back plate can be in the range of 0.5 mm to 2.5 mm, such as 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 arrangement of the plurality of columns can be in the range of 3 mm to 8 mm, such as 4 mm to 7.5 mm, preferably 6.5 mm.

[0030] As mentioned above, the columns are made of a soft magnetic material, such as electrical steel (magnetic steel). The columns and the back plate can be made of the same material. Preferably, the magnetic core of the drive unit, comprising the columns and the back plate, is made of cobalt steel. The use of cobalt steel helps to reduce the size, in particular the diameter, of the pump. Among all magnetic steels, cobalt steel has the highest magnetic permeability and the highest magnetic saturation flux density, producing the most magnetic flux when using the same amount of material.

[0031] The dimensions of the pillars, particularly their length and cross-sectional area, can vary and depend on various factors. In contrast to the dimensions of the blood pump (e.g., outer diameter), which are determined by its application, the dimensions of the pillars are determined by electromagnetic properties, which are adjusted to achieve the desired performance of the drive unit. One of these factors is the flux density to be achieved through the minimum cross-sectional area of ​​the pillars. The smaller the cross-sectional area, the higher the current required to achieve the desired magnetic flux. However, due to electrical resistance, higher currents generate more heat in the coil wires. More importantly, if the pillar cross-section is too small, the stator material will quickly become magnetically saturated. This means that while "thin" pillars are preferred to reduce overall size, this will require high currents and thus lead to undesirable heating. The heat generated in the wires also depends on the length and diameter of the wire used for the coil windings. Short wire lengths and large wire diameters are preferred to minimize winding losses (referred to as "copper losses" or "copper power losses" if copper wire is used, which is the typical case). In other words, if the wire diameter is small, then more heat is generated at the same current compared to a thicker wire, with a preferred wire diameter being, for example, 0.05 mm to 0.2 mm, such as 0.1 mm. Other factors that influence the column size and the performance of the drive unit are the number of windings of the coil and the outer diameter of the windings (i.e. the column comprising the windings). Many windings can be arranged in more than one layer around each column, for example, two or three layers can be provided. However, the higher the number of layers, the more heat will be generated due to the increased length of the wire in the outer layers with the larger winding diameter. The increased length of the wire may generate more heat due to the higher resistance of the long wire compared to a shorter wire. Therefore, a single layer of windings with a small winding diameter would be preferred, but due to the required power, more than one winding is usually provided.

[0032] A typical number of windings, which in turn depends on the length of the column, may be about 50 to about 150, for example 56 or 132. Independent of the number of windings, the coil windings are made of a conductive material, in particular a metal such as copper or silver. Silver may be preferred over copper because it has a resistance that is about 5% less than that of copper.

[0033] Preferably, at least one column, more preferably each column, has a triangular cross-section transverse to the longitudinal axis of the column. Preferably, the cross-section of the column is triangular over its entire length. Triangular columns can make high-proportion use of the available space in the pump casing, because such columns can be densely packed around the axis of rotation. Preferably, one side of the triangle faces away from the axis of rotation and is curved. The curved portion is curved around the axis of rotation. The radius of the curved portion preferably corresponds to the radius of the outer diameter defined by the plurality of columns arranged around the axis of rotation. By means of such a curved portion, it is possible to further increase the use of the interior space of the cylindrical pump casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The summary of the application above and the detailed description below will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the disclosure, the drawings are referred to in the detailed description. The scope of the disclosure, however, is not limited to the specific embodiments disclosed in the drawings. In the drawings:

[0035] Figure 1 A cross-sectional view of an intravascular blood pump is shown;

[0036] Figure 2 A cross-sectional view of a first embodiment of the arrangement of drive unit - impeller is shown;

[0037] Figure 3A And Figure 3B A cross-sectional view of a first embodiment of the arrangement of drive unit - impeller is shown; Figure 1 And Figure 2 A side view and perspective view of the magnetic core of the drive unit of the arrangement of drive unit - impeller according to

[0038] Figure 4 The winding of the six columns of the magnetic core of Figure 3A And Figure 3B is schematically shown;

[0039] Figures 5A to 5D Side views of the impeller side end of the column according to four different embodiments are shown, respectively;

[0040] Figure 6A A spacer for the arrangement of drive unit - impeller according to Figure 2 is shown in perspective view;

[0041] Figure 6B A front view of the spacer of Figure 3A is shown;

[0042] Figure 6C Side views of the spacer of Figure 3A And Figure 3B are shown;

[0043] Figure 7A A perspective view of a first layer back plate with openings for the columns of the drive unit of the arrangement according to Figure 2 is shown;

[0044] Figure 7B A perspective view of a second layer back plate without openings for the columns of the drive unit of the arrangement according to Figure 2 is shown;

[0045] Figure 7C A cross-sectional view of an assembled back plate comprising a first layer of Figure 7A And a second layer of Figure 7B is shown;

[0046] Figures 8A to 8Dshows the further manufacture according to Figure 2 The arrangement of the drive unit column is an intermediate product of the manufacturing stage;

[0047] Figures 9A to 9C Shown according to Figure 5C Welding parts on intermediate products;

[0048] Figure 10 Shown from the Figures 8A to 9C A perspective view of the column from which the intermediate product prepared is separated;

[0049] Figure 11 Shown Figure 9A a front view of the intermediate product on a plane having two weld seams and two cross sections of a column to be cut out of the intermediate product;

[0050] Figure 12 A front view of the end surface of the column with the weld is shown;

[0051] Figure 13 A cross-sectional view showing a second embodiment of a drive unit-impeller arrangement;

[0052] Figures 14A to 14C shows the manufacturing method for Figure 13 The step of forming an integrated magnetic core of a drive unit; and

[0053] Figures 15A to 15C Shown in the following Figures 14A to 14C One or more welds may be provided on the surface of the manufactured integral magnetic core. DETAILED DESCRIPTION

[0054] refer to Figure 1 , which shows a cross-sectional view of a blood pump 1. The blood pump 1 comprises a pump housing 2 having a blood flow inlet 21 and a blood flow outlet 22. The blood pump 1 is designed as an intravascular blood pump, also known as a catheter pump, and is arranged into a patient's blood vessel by means of a catheter 25. The blood flow inlet 21 is at the end of a flexible sleeve 23, which can be placed through a heart valve, such as the aortic valve, during use. The blood flow outlet 22 is located in a side surface of the pump housing 2 and can be placed in a heart vessel, such as the aorta. The blood pump 1 is electrically connected to an electrical wire 26, wherein the electrical wire 26 extends through the catheter 25 to supply power to the blood pump 1 so as to drive the pump 1 by means of a drive unit 4, as explained in more detail below.

[0055] If the blood pump 1 is intended for long-term use, i.e., when the blood pump 1 is implanted in a patient for weeks or even months, it is preferably supplied with power by means of a battery. This allows the patient to be mobile, since the patient is not connected to a base station by a cable. The battery can be carried by the patient and can supply power to the blood pump 1, for example, wirelessly.

[0056] Blood is conveyed along a passage 24 connecting a blood flow inlet 21 and a blood flow outlet 22 (arrows indicate blood flow). Impeller 3 is configured to convey blood along passage 24 and is rotatably mounted within pump housing 2 about a rotation axis 10 by means of a first bearing 11 and a second bearing 12. Rotation axis 10 is preferably the longitudinal axis of impeller 3. In this embodiment, both bearings 11 and 12 are contact-type bearings. However, at least one of bearings 11 and 12 may be a non-contact bearing, such as a magnetic bearing or a hydrodynamic bearing. First bearing 11 is a pivot bearing having a spherical bearing surface that allows rotational motion and some degree of pivotal motion. Pin 15 is provided to form one of the bearing surfaces. Second bearing 12 is arranged in a support member 13 to stabilize the rotation of impeller 3. Support member 13 has at least one opening 14 for blood flow. Blades 31 are provided on impeller 3 to convey blood as impeller 3 rotates. Rotation of impeller 3 is induced by drive unit 4, which is magnetically coupled to a magnetic structure 32 at the end portion of impeller 3. The blood pump 1 shown is a hybrid blood pump, wherein the main flow direction is axial. It is understood that the blood pump 1 can also be a pure axial blood pump, depending on the arrangement of the impeller 3, in particular the blades 31.

[0057] The blood pump 1 comprises an impeller 3 and a drive unit 4. The drive unit 4 comprises a plurality of columns 40, for example six columns 40, only two of which are Figure 1 . The columns 40 are arranged parallel to the axis of rotation 10, more specifically, the longitudinal axis of each of the columns 40 is parallel to the axis of rotation 10. One end of the column 40 is arranged adjacent to the impeller. Coil windings 44 are arranged around the columns 40. The coil windings 44 are sequentially controlled by a control unit to generate a rotating magnetic field. Part of the control unit is a printed circuit board 6 connected to the electrical wires 26. The impeller has a magnetic structure 32, which is formed as a multi-piece magnet in this embodiment. The magnetic structure 32 is arranged at the end of the impeller 3 facing the drive unit 4. The magnetic structure 32 is arranged to interact with the rotating magnetic field to cause the impeller 3 to rotate around the axis of rotation 10.

[0058] To close the magnetic flux path, a back plate 50 is positioned at the end of the posts 40 opposite to the impeller side of the posts. The posts 40 act as a magnetic core and are made of a suitable material, in particular a soft magnetic material, such as steel or a suitable alloy, in particular cobalt steel. Likewise, the back plate 50 is made of a suitable soft magnetic material, such as cobalt steel. The back plate 50 enhances the magnetic flux, which allows for a reduction of the overall diameter of the blood pump 1, which is important for an intravascular blood pump. For the same purpose, a magnetic yoke 37, i.e. a further impeller back plate, is provided in the impeller 3 at the side of the magnetic structure 32 facing away from the drive unit 4. The magnetic yoke 37 has a conical shape in the present embodiment to direct the blood flow along the impeller 3. The magnetic yoke 37 can also be made of cobalt steel. One or more flushing channels extending towards the central bearing 11 can be formed in the magnetic yoke 37 or the magnetic structure 32.

[0059] Figure 2 A cross-sectional view of a first preferred embodiment of a drive unit-impeller arrangement for a blood pump according to Figure 1 is shown. As can be seen from Figure 2 , the impeller side end 420 of the posts 40 does not extend radially beyond the windings 44. Rather, the cross-section of the posts 40 is constant in the direction of the longitudinal axis LA of the posts 40. This avoids that the posts 40 come close to each other, as this would cause a partial magnetic short circuit and thus result in a reduced motor power of the blood pump.

[0060] The drive unit according to Figure 2 may comprise at least two posts 40. The number of posts is preferably a multiple of three, thus it can be three, nine or twelve. Alternatively, the number of posts 40 can be a multiple of two, such as two, four, six, eight, ten or twelve. A higher number of posts 40 can be possible. The number of posts 40 is preferably six. Due to the cross-sectional view, only two posts 40 are visible. The posts 40 and the back plate 50 form a magnetic core 400 of the drive unit 4, which can have a diameter of less than 10 mm.

[0061] As shown, the posts 40 can be composed of a discontinuous soft magnetic material, which is discontinuous in terms of electrical conductivity. The discontinuous soft magnetic material comprises a plurality of sheet materials 85 made of a ferromagnetic material and stacked on top of each other. The stacking direction is arranged in the direction of the longitudinal axis LA of the posts 40 and is marked by an arrow DL. As shown, the posts 40 are arranged parallel to the rotation axis 10.

[0062] A spacer 7 is provided around the posts 40. It is made of a non-magnetic material and has the effect that the distance between the posts 40 is kept constant at the impeller side end of the posts 40. The spacer 7 will be described in further detail with respect to Figures 6A to 6C . The impeller side end 424 of the coil winding 44 extends to the spacer 7. At the other end of the posts 40, a back plate 50 is provided. According to Figure 2The embodiment shown, the back plate 50 has recesses for receiving the posts 40 therein. More specifically, it comprises a first layer 51 having openings 511 for the rear end portions 450 of the posts 40. The back plate 50 will be described in more detail with respect to Figures 7A to 7C Further embodiments will be described in more detail.

[0063] It is conceivable to realize embodiments of the blood pump 1 having any combination of the three features described above: the impeller-side end portions 420 of the posts 40 do not extend radially beyond the impeller-side end portions 424 of the windings 44, the non-magnetic spacers 7 are provided between the posts 40, and the back plate 50 has recesses for receiving the rear end portions 450 of the posts 40.

[0064] Figure 3A and Figure 3B Fig. 1 shows a side view of a drive unit 4 according to the Figure 1 and 2 Fig. 1 shows a side view of a drive unit 4 according to the

[0065] Thus, the slope of the concave surface extends to the outer periphery of the front surface 42. When viewed in a cross-sectional plane that is vertical through the front surface 42, the concave surface has a triangular cross-section, the plane being perpendicular to the longitudinal axis of the respective post 40 in the embodiment shown. This is different from the embodiment described in WO 2017 / 162619 A1, in which the front surface 42 of each post 40 is inclined so as to together form a conical front side of the magnetic core 400. That is, in WO 2017 / 162619 A1, each post has a stem portion and a head portion that is inclined at the impeller-side end of the stem portion. In addition, those head portions, although inclined, their front surfaces can be provided with the aforementioned concave surface in which the front surface slopes downwardly towards the central region of the front surface and has a triangular cross-section when viewed in a cross-sectional plane that is vertical through the front surface.

[0066] The slope of the front surface 42 within the concave surface downwardly towards the central region of the front surface serves to concentrate and thus to bundle the magnetic field lines that run through the front surface, as will be described in more detail below with respect to Figure 4Further explained. However, within the concave surface, the front surface 42 not only slopes downward toward the center of the front surface 42, but also slopes further downward radially outward relative to the axis of rotation 10. In other words, the radially inner region of the front surface 42 within the concave surface protrudes axially from the radially outer region of the front surface 42 within the concave surface. This radially outward downward slope has the effect of directing magnetic field lines toward the periphery of the impeller's magnetic structure 32, thereby increasing the lever arm for rotating the impeller 3 and, in turn, increasing torque. Therefore, the concave surface's slope, both toward the center of the front surface 42 and radially outward, results in the concave surface being open toward the side surfaces of the post 40 that lie radially outward relative to the axis of rotation for the post 40 having a triangular cross-section. Consequently, the maximum depth point of the front surface 42 is located at the outer periphery of the respective post 40 and may range from 0.05 mm to 0.3 mm, preferably from 0.1 mm to 0.2 mm, and most preferably approximately 0.2 mm.

[0067] Figure 4 The magnetic core 400 (eg Figure 3A and Figure 3B The six windings 40a, 40b of the magnetic core 400 (shown in FIG) are shown. To generate a rotating magnetic field, two aspects are important. First, some of the legs must be magnetized in the positive direction, while others must be magnetized in the negative direction, so that the magnetic field lines of the magnetic flux extend from the positively magnetized legs through the magnetic structure 32 of the impeller 3 into the negatively magnetized legs, and further back through the back plate 50 to the positively magnetized legs to generate a closed magnetic field. Second, the magnetization direction of the legs must change sequentially from one leg to another in the circumferential direction to pull the magnetic structure 32 of the impeller 3 to rotate about the rotation axis 10. To achieve this, adjacent legs are magnetized in opposite directions by flowing appropriately oriented currents through the coil windings 44 arranged around each leg 40. For example, the first leg can be magnetized positively, the adjacent second leg negatively, the adjacent third leg positively, the adjacent fourth leg negatively, and so on. However, in a preferred embodiment, there are always two adjacent poles magnetized in one direction to drag the magnetic structure 32 of the impeller 3, and only one immediately following pole is magnetized in the opposite direction. In the case of six poles, four poles 40b are magnetized in one direction and two poles 40a are magnetized in the opposite direction, as schematically shown for a winding of six poles. Figure 4 As shown. Figure 4 As can be further seen in FIG, the magnetic field lines 500 extending through the concave front surface 42 are concentrated by the inclined surfaces in the concavity, so that the magnetic field lines form a bundle. Thus, the risk of short circuits is minimized in the sense that the magnetic field lines 500 connect between adjacent pillars 40a and 40b.

[0068] Figures 5A to 5DA side view of the impeller-side end 420 of a column according to four different embodiments is shown respectively. Figure 5A The embodiment shown corresponds to the embodiment described above with a concave surface having an outer periphery that coincides with the outer periphery of the front surface and having two inclined side walls 42a that, as described above, are both inclined downwardly toward the central area of ​​the front surface 42 and radially outwardly relative to the axis of rotation. Thus, when viewed in any cross-sectional plane passing vertically through the front surface 42, the concave surface has a triangular cross-section and is open radially outwardly of the column.

[0069] Figure 5B The embodiment shown corresponds essentially to Figure 5A , except that it has a flat bottom 42b. Thus, the concave triangular cross-section is limited radially inward of the column relative to the axis of rotation. Further radially outward, the cross-section becomes trapezoidal. Thus, bottom 42b is flat and parallel to the general plane of front surface 42, while sidewall 42a is a straight sidewall with an oppositely inclined orientation.

[0070] exist Figure 5C In the embodiment shown, the concave surface has curved, sloping sidewalls 42 a such that the slope of the concave surface is greatest at the periphery of the front surface 42 .

[0071] Figure 5D The embodiment shown is Figure 5B and 5C The embodiment shown is a combination of the above, i.e. the concave surface has a flat bottom 42b and curved, sloping sidewalls 42a.

[0072] Figures 6A to 6C The figure shows a perspective view, a front view, and a side view of a spacer 7, respectively. The spacer 7 generally has the form of a disk or wheel with a through-hole 75 in the center. The spacer 7 includes an opening 71 for each of the pillars. For an embodiment with six pillars 40, six openings 71 are provided as shown. Spacer spokes 72 are arranged between the openings 71. When a pillar 40 is inserted into an opening 71, the spacer spokes 72 maintain the distance between the pillars 40. Furthermore, the spacer 7 includes an outer ring 73 and an inner ring 74, which connect adjacent spacer spokes 72 and stabilize the spacer. The spacer 7 is made of titanium, a paramagnetic material that prevents magnetic short circuits when placed between the impeller-side ends 420 of the pillars 40. Titanium offers high mechanical strength, allowing for the manufacture of a spacer 7 with a small thickness. This is advantageous considering the required construction space. Furthermore, titanium has a low electrical conductivity, minimizing eddy current losses, and is easy to machine. However, any other non-magnetic material may also be used, as long as it is stable, can be machined with high precision, and does not readily conduct electricity. It is also possible to use diamagnetic materials, as they can resist external magnetic fields.

[0073] Figure 7AA perspective view of the first layer 51 of the back plate 50 is shown. The first layer 51 is generally in the shape of a disk or wheel with a hole 515 in the center. The first layer 51 includes openings 511 into which the rear ends 450 of the posts 40 are to be arranged. The first layer 51 includes spaced spokes 512 arranged between the openings 511. One function of the spaced spokes 512 is to keep the distance between the rear ends 450 of the posts 40 constant. Further, the first layer 51 includes an outer ring 513 and an inner ring 514 connecting the spaced spokes 512 at the radially outer end and the radially inner end of the opening 511, respectively. The first layer 51 can be made of a discontinuous soft magnetic material that is discontinuous in electrical conductivity. As Figure 7A As shown, it can include several ferromagnetic sheets 85, specifically three sheets. Sheets 85 are laminated with a non-conductive material to form a discontinuous soft magnetic material. The lamination direction DL is generally parallel to the sheets 85, and the main extension direction of the sheets defines the lamination plane. Within the backplate 50, the sheets 85 are perpendicular to the axis of rotation 10. A hole 515 is arranged in the center of the first layer 51. This hole serves to facilitate assembly of the first layer 51 with the second layer 52, for example, to center the first layer 51 and the second layer 52.

[0074] exist Figure 7B , a perspective view of the second layer 52 of the back plate 50 is shown. The second layer 52 essentially has the form of a disk with a hole 525 in the middle corresponding to the hole 515 in the first layer 51. The second layer 52 does not have any opening for the rear end of the column 40. Instead, the second layer 52 has a contact plane 526 facing the rear end 450 of the column 40. The rear end 450 of the column is in contact with the contact plane 526 of the second layer 52 of the back plate 50 in the assembled state of the drive unit to transfer magnetic flux between the rear end 450 of the column 40 and the back plate 50. Since all the rear ends 450 of the columns 40 are in contact with the contact plane 526, magnetic flux can be exchanged between the columns 40 and a magnetic zero point can be formed in the second layer 52. In order 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 sheets 85 stacked together, similar to the structure described above with respect to the first layer 51. As an example, Figure 7B The three sheets 85 shown may form the second layer 52. In the second layer 52, the stacking direction D is perpendicular to the axis of rotation 10. The sheets 85 are ferromagnetic and electrically conductive, while the intermediate layers (not explicitly shown) between the sheets 85 are non-ferromagnetic and electrically non-conductive. This type of discontinuous soft magnetic material reduces eddy currents, which would otherwise be generated in greater quantities due to 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, by aligning the first and second layers 51, 52.

[0075] Figure 7CA cross-section of a back plate 50 is shown. It consists of a first layer 51 and a second layer 52, which are bonded to each other at their major surfaces with the greatest extension. The bond between the first and second layers 51, 52 of the back plate 50 can be established in the same manner as between the sheets 85 of the first and second layers 51, 52. The holes 515 of the first layer 51 and the holes 525 of the second layer 52 are aligned 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, forming a recess 501 to accommodate 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, its rear end 450 contacts the contact plane 526. Furthermore, the position of the post 40 is secured by the spaced spokes 512, as well as the outer and inner rings 513, 514, which together surround each post 40. In this way, a magnetic connection is established between the second layer 52 and the rear end surface 45 of the post 40 at the contact plane 526, and in addition, a second magnetic connection is established between the post 40 and the above-mentioned surrounding portion of the first layer 51. However, the main part of the magnetic flux is transferred via the contact plane 526. Preferably, both the surface at the rear end 450 of the post 40 and the contact plane 526 have a predefined flatness. In this way, the gap between the surface 45 at the rear end 450 of the post 40 and the contact plane 526 can be kept below a certain value, preferably less than 10 μm. This improves the transfer of magnetic flux between the post 40 and the backplate 50. Preferably, no additional material is present between the surface 45 at the rear end 450 of the post 40 and the contact plane 526. In this embodiment of the invention, the transfer of magnetic flux via the surface 45 and the backplate 50 is independent of the way in which the post 40 is fastened to the backplate 50.

[0076] Figures 8A to 8D The preparation steps for producing column 40 are shown. Figure 8A A perspective view of a plate 8 made of a discontinuous soft magnetic material which is discontinuous in terms of electrical conductivity, also referred to as workpiece, is shown.

[0077] exist Figure 8A , the plate 8 is marked with a width W for cutting a workpiece rod 81 from the plate 8. The width W of the workpiece rod 81 is equal to the length of the column 40 to be manufactured from the workpiece rod 81. Figure 8A The enlarged view of the portion indicated by the rectangle R in Figure 8B Here, the stacked discontinuous sheets 85 of soft magnetic material can be seen. The stacking direction DL extends along the main plane of the plate 8 and thus forms the stacking plane.

[0078] Figure 8C A workpiece bar 81 is shown cut from a sheet 8 as separate pieces of discrete material. Figure 8C The enlarged view of the portion indicated by the rectangle R in Figure 8DThe sheet 85 of the workpiece bar 81 can be seen in this view.

[0079] Figure 9A Shown Figure 8C and Figure 8D The workpiece rod 81 forms the basis for the welding step in preparation for cutting the column 40 from the rod 81. Figure 9A , a plurality of cross sections 84 of the column 40 to be manufactured from the rod 81 are depicted in the side plane on the left. The column 40 is manufactured by cutting these cross sections 84 from the rod 81. Since the width W of the rod 81 corresponds to the length of the column 40, the side surfaces 811 and 812 of the rod 81 become the end surfaces at the impeller-side end 420 and the rear end 450 of the column 40.

[0080] Figure 9B The next preparation step before cutting out the column 40 is shown. Two welds 82 and 83 are welded at a distance from each other on the side 811 of the rod 81 and pass through each of the cross-sections 84 to be cut out of the column 40. Welds 82 and 83 extend perpendicular to the lamination direction DL of the sheet 85. In this way, the sheets of discontinuous material are connected to each other. Instead of two welds, a single weld can be provided. In addition, a similar weld can be provided on the opposite side 812 of the rod 81. The sheets 85 have a better mechanical connection to each other due to welds 82 and 83, and are also electrically connected. The latter has the advantage that current can flow from any location of the discontinuous soft magnetic material that is desired to become the column 40 to each location of the rod 81 that may be required for, for example, electrical discharge machining. In this way, electrical discharge machining is significantly facilitated. Moreover, because the cut column 40 does not delaminate, higher processing reliability is achieved. Preferably, laser welding is applied. It may be advantageous to apply welding power twice or more frequently to the same weld. The portion of the rod 81 indicated by the rectangle R is Figure 9C Shown enlarged.

[0081] therefore, Figure 9C A plurality of cross sections 84 of the column 40 are shown to be cut from the rod 81. The cross sections 84 have a substantially triangular shape. As shown, the corners may be rounded. Figure 9C The convex side 842 shown on the left side of the cross section 84 has a convex form. 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 cross section 84 at the corner 841 opposite the convex side 842 of the cross section 84 is aligned with the lamination direction DL. Thus, the sheet 85 extends symmetrically across the cross section 84.

[0082] Figure 10The column 40 is shown having been cut from the rod 81. As can be seen, welds 82 and 83 are still present on the surface 45 at the rear end 450 of the rod 81. The column 40 has a constant cross-section 84 along its entire length. If desired, the welds 82 and 83 can be deburred after the column 40 is cut. Simultaneously or in a subsequent step, a cross-section having a cross-section such as the following is cut on the surface of the opposite end of the column 40. Figures 5A to 5D The concave surface may be formed in any of the configurations shown, or in a different configuration, which surface will later form the front surface 42 of the impeller-side end 420 of the post 40. Alternatively, the concave surface may be formed, for example by wire discharge machining, before providing the weld and cutting the post 40 from the rod 81.

[0083] Figure 11 Another arrangement of two sections 84 on the side 811 of the workpiece bar 81 is shown. Figures 9A to 9C In contrast to the workpiece rod 81 shown in FIG. Figure 11 The side surface 811 of the workpiece rod 81 has a size that allows two sections 84 to be arranged next to each other in a direction perpendicular to the stacking direction DL. The sections 84 are oriented relative to the stacking direction DL so that the bisector B of the angle of each section 84 opposite its respective convex side edge 842 is aligned with the stacking direction DL. This way of arranging the sections 84 along the rod 81 saves material. Less waste material is generated. It is conceivable to stack even more sections 84 of the column 40 in a direction perpendicular to the stacking direction DL, depending on the thickness of the rod 81 and the required cross-sectional dimensions of the column 40. Each of the welds 82 and 83 passes through each of the sections 84. The welds 82, 83 pass through the entire side surface 811 of the rod 81 in a direction perpendicular to the stacking direction DL. In this way, all sheets 85 of the discontinuous soft magnetic material of the rod 81 are connected to each other.

[0084] Figure 12 FIG. 8 shows an example of a column 40 cut from a welded rod 81, namely a front view of the rear end surface 45 of the column 40. Figure 12 As shown, a single weld 86 having a relatively large width, which may cover more than about one-third of the height of the triangular section 84, extends along the convex side 842 of the section 84. The weld 86 extends perpendicular to the lamination direction DL to connect all the sheets thereof. However, as Figure 11 The two welds shown are more preferred than a single weld.The bisector B of the corner 841 opposite the convex side 842 is again aligned with the lamination direction DL.

[0085] Figure 13 Shown for Figure 1 A second embodiment of the arrangement of the drive unit - impeller of the blood pump 1. Figure 2In the first embodiment shown in FIG, the front surface 42 of the impeller-side end 420 has a concave surface that tapers radially outward away from the magnetic structure 32 of the impeller 3. Furthermore, the impeller-side end 420 of the post 40 does not extend radially beyond the winding 44. Rather, the cross-section of the post 40 remains constant in the direction of the longitudinal axis LA of the post 40. This prevents the posts 40 from coming close together, as this would cause local magnetic short circuits and thus reduce the power of the blood pump's motor.

[0086] Similarly, according to Figure 13 The drive unit 4 may include at least two pillars 40. The number of pillars is preferably a multiple of three, and thus can be three, nine, or twelve. Alternatively, the number of pillars can be a multiple of two, such as two, four, six, eight, ten, or twelve. A greater number of pillars 40 is also possible. The number of pillars 40 is preferably six. Due to the cross-sectional view, only two pillars 40 are visible. The pillars 40 and the back plate 50 form the magnetic core 400 of the drive unit 4, which can have a diameter of less than 10 mm.

[0087] The second embodiment and Figure 2 The difference from the first embodiment shown in the figure lies in the different structure of the magnetic core. Here, the magnetic core 400 includes the magnetic components of the drive unit 4 as a single piece or block, the magnetic components being the column 40 and the back plate 50. The block is composed of a discontinuous soft magnetic material. The discontinuous soft magnetic material is discontinuous in terms of electrical conductivity. As shown in the figure, it includes a plurality of sheets 85 of ferromagnetic material, which are stacked together to form a structure such as Figure 14C The monolithic block 9 is shown with the lamination direction DL parallel to the axis of rotation 10 .

[0088] The coil winding 44 extends to the impeller-side end 420 of the column 40. This has the advantage that a magnetomotive force can be generated along the entire column 40. The magnetic core 400 includes a protrusion 401 that protrudes radially away from the column 40 at the rear end 450 of the column 40. This protrusion 401 forms a stop for the coil winding 44 toward the back plate 50. Because the integral magnetic core 400 connects the back plate 50 and the column 40 with high rigidity, spacers between the columns 40 at the impeller-side end 420 of the column can be omitted. The integral magnetic core 400 provides the advantage of achieving an optimal magnetic connection between the column 40 and the back plate 50. The magnetic core 400 can have a diameter of less than 10 mm.

[0089] Figures 14A to 14C shows the manufacturing process for Figure 13 The arrangement of the drive unit - impeller of the magnetic core 400 of the drive unit 4 is shown in the steps. Figure 14AA cube-shaped monolith 9 is shown in perspective view, which forms a workpiece for manufacturing a magnetic core 400. The monolith 9 consists of a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity. It comprises sheets 85 oriented in a lamination direction DL extending along the main plane of the sheet 85. The sheets 85 are each bonded to their respective adjacent sheets by a bonding layer of non-conductive material, which is Figures 14A to 14C Not explicitly shown.

[0090] Figure 14B The magnetic core 400 is shown in a semi-manufactured state after being machined from a cubic monolithic block 9 into a substantially cylindrical body 94. During this machining step, the protrusions 401 are manufactured. The reduced diameter sections 404 of the body 94, which form the outer peripheral surface of the legs 40 of the magnetic core 400, are manufactured to have a diameter corresponding to the outer diameter of the outermost convex side 842 of the legs 40, wherein the larger diameter section 405 will later form part of the back plate 50.

[0091] The body 94 is then further manufactured to produce Figure 14C . For this production step, electrical discharge machining can be used. For example, electrical discharge machining by wire cutting can be applied to produce gaps 49 separating the columns 40 from one another. Inside the gaps, space is provided for the coil windings 44. At the bottom of the gaps 49, a central region 59 of the integral backing plate 50 extends between the rear ends of the columns 40. The central region 59 is integral with the columns 40 and with the backing plate 50. Thus, the entire magnetic core is formed from a single block 9.

[0092] The lamination direction DL in the magnetic core 400 is such that it is parallel to the axis of rotation 10. It is acceptable for the lamination direction DL in the back plate 50 to be non-parallel with respect to the magnetic flux between the pillars 40 in the back plate 50. The magnetic core 400 can also be made of a wound soft magnetic sheet material separated by non-conductive layers. In this case, the lamination direction DL in the back plate 50 is always circumferential, which is advantageous for avoiding eddy currents in the magnetic flux in the back plate 50.

[0093] Figures 15A to 15C Shown in the following Figures 14A to 14CHow one or more welds can be provided on the surface of the manufactured one-piece magnetic core. Accordingly, in the embodiment shown, three welds 82, 83 are provided on one side of the cubic monolith 9. The welds 82, 83 are welded at a distance from each other and through the cross section of the body 94 to be cut out from the monolith 9. The welds 82, 83 extend perpendicular to the stacking direction DL of the sheet 85. In this way, the sheets of discontinuous soft magnetic material are connected to each other. Instead of three welds, more welds or a single wider weld can be provided. In addition, similar welds can be provided on the opposite side of the monolith 9 (not shown). Instead of or in addition to the welds on the opposite side, one or more welds can be provided on the side surface of the monolith 9 at the level of the back plate 50 to completely or at least partially surround the back plate 50. The sheets 85 are better mechanically connected to each other due to the welds 82 and 83, and are also electrically connected. The advantage of the latter is that current can flow from any location in the discontinuous soft magnetic material to each location in the body 94 where electrical connections may be required, for example, for electrical discharge machining. This significantly facilitates electrical discharge machining. Furthermore, higher processing reliability is achieved because the back plate-pillar unit to be cut from the body 94 does not delaminate. Preferably, laser welding is applied. Applying welding power twice or more frequently to the same weld may be advantageous.

[0094] The body 94 is then machined to form Figure 15C . In this second embodiment, the concave surface in the front surface 42 of the column 40 has three inclined side walls instead of two, each of which has a downward slope toward the center of the front surface. The outer periphery of the concave surface coincides with the outer periphery of the front surface 42 of the column 40. However, the concave surface does not open to any side surface of the column 40. It is worth noting that, as Figure 14C The embodiment shown in FIG. 1 with only two inclined side walls is more efficient and is therefore preferred.

Claims

1. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump housing (2), the pump housing (2) having a blood flow inlet (21) and a blood flow outlet (22), an impeller (3) arranged in the pump housing (2) so as to be rotatable about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey 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 plurality of columns (40) arranged around the rotation axis (10), wherein each of the columns (40) has an impeller-side end (420) pointing toward the impeller (3), the impeller-side end (420) having a front surface (42) facing the impeller (3), and a coil winding (44) disposed about each of the posts (40) to generate magnetic field lines (500) passing through the front surface (42) of each of the posts (40), and the coil winding (44) being controllable to generate a rotating magnetic field, wherein the impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field to cause the impeller (3) to rotate, wherein the front surface (42) of at least one of the posts (40) comprises a concave surface in which the front surface (42) slopes downwardly towards a central region of the front surface (42), i.e., in a direction away from the impeller (3), so as to concentrate at least a portion of the magnetic field lines (500) passing through the front surface (42); and wherein said at least one of said columns (40) has a longitudinal axis (LA) and a constant cross-section at least in the impeller-side end region of said at least one of said columns (40) such that its impeller-side end (420) radially extends no further than an impeller-side end (424) of said coil winding (44) arranged around said at least one of said columns (40), wherein the term radial relates to a direction transverse to said longitudinal axis (LA).

2. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump housing (2), the pump housing (2) having a blood flow inlet (21) and a blood flow outlet (22), an impeller (3) arranged in the pump housing (2) so as to be rotatable about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey 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 plurality of columns (40) arranged around the rotation axis (10), wherein each of the columns (40) has an impeller-side end (420) pointing toward the impeller (3), the impeller-side end (420) having a front surface (42) facing the impeller (3), and a coil winding (44) disposed about each of the posts (40) to generate magnetic field lines (500) passing through the front surface (42) of each of the posts (40), and the coil winding (44) being controllable to generate a rotating magnetic field, wherein the impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field to cause the impeller (3) to rotate, wherein the front surface (42) of at least one of the posts (40) comprises a concave surface in which the front surface (42) slopes downwardly towards a central region of the front surface (42), i.e., in a direction away from the impeller (3), so as to concentrate at least a portion of the magnetic field lines (500) passing through the front surface (42); and At least one of the columns comprises or consists of a discontinuous soft magnetic material, which is discontinuous in terms of conductivity in a cross section transverse to the longitudinal axis (LA) of the corresponding column (40) so as to provide at least one discontinuity in terms of conductivity in the discontinuous soft magnetic material, and wherein at least one weld (82, 83, 86) is provided on a surface (811) of the discontinuous soft magnetic material, the weld (82, 83, 86) connecting the at least one discontinuity in terms of conductivity in the discontinuous soft magnetic material.

3. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump housing (2), the pump housing (2) having a blood flow inlet (21) and a blood flow outlet (22), an impeller (3) arranged in the pump housing (2) so as to be rotatable about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey 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 plurality of columns (40) arranged around the rotation axis (10), wherein each of the columns (40) has an impeller-side end (420) pointing toward the impeller (3), the impeller-side end (420) having a front surface (42) facing the impeller (3), and a coil winding (44) disposed about each of the posts (40) to generate magnetic field lines (500) passing through the front surface (42) of each of the posts (40), and the coil winding (44) being controllable to generate a rotating magnetic field, wherein the impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field to cause the impeller (3) to rotate, wherein the front surface (42) of at least one of the posts (40) comprises a concave surface in which the front surface (42) slopes downwardly towards a central region of the front surface (42), i.e., in a direction away from the impeller (3), so as to concentrate at least a portion of the magnetic field lines (500) passing through the front surface (42); and Each of the columns (40) has a rear end portion (450), wherein the drive unit (4) includes a back plate (50) connecting the rear end portions (450) of the columns (40) and extending between the columns (40) in a middle region (59), wherein the material of at least one of the columns (40) is integral with the material of the middle region (59) of the back plate (50).

4. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump housing (2), the pump housing (2) having a blood flow inlet (21) and a blood flow outlet (22), an impeller (3) arranged in the pump housing (2) so as to be rotatable about a rotation axis (10), the impeller (3) having blades (31) sized and shaped to convey 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 plurality of columns (40) arranged around the rotation axis (10), wherein each of the columns (40) has an impeller-side end (420) pointing toward the impeller (3), the impeller-side end (420) having a front surface (42) facing the impeller (3), and a coil winding (44) disposed about each of the posts (40) to generate magnetic field lines (500) passing through the front surface (42) of each of the posts (40), and the coil winding (44) being controllable to generate a rotating magnetic field, wherein the impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field to cause the impeller (3) to rotate, wherein the front surface (42) of at least one of the posts (40) comprises a concave surface in which the front surface (42) slopes downwardly towards a central region of the front surface (42), i.e., in a direction away from the impeller (3), so as to concentrate at least a portion of the magnetic field lines (500) passing through the front surface (42); and Each of the columns (40) has a rear end portion (450), wherein the drive unit (4) includes a back plate (50) connected to the rear end portions (450) of the columns (40), and wherein at least one of the rear end portions (450) of the columns (40) has a rear end surface (45) in contact with the back plate (50).

5. The intravascular blood pump (1) according to any one of claims 1 to 4, wherein the concave surface extends to the periphery of the front surface (42).

6. An intravascular blood pump (1) according to claim 5, wherein the concave surface extends to the periphery of the front surface (42) at least on both sides of the front surface, and the two sides are closest to adjacent columns (40) among the multiple columns (40), or the concave surface extends to the periphery of the front surface (42) on both sides of the front surface, and the two sides are closest to adjacent columns (40) among the multiple columns (40).

7. The intravascular blood pump (1) according to claim 5, wherein the periphery of the concave surface coincides with the periphery of the front surface (42).

8. Intravascular blood pump (1) according to any one of claims 1 to 4, wherein the concave surface has a flat bottom (42b).

9. Intravascular blood pump (1) according to claim 8, wherein the concave surface has rectilinearly inclined side walls (42a) when viewed in a cross-sectional plane passing vertically through the front surface (42).

10. The intravascular blood pump (1) according to claim 8, wherein the concave surface has curved and inclined side walls (42a) when viewed in a cross-sectional plane passing vertically through the front surface (42).

11. Intravascular blood pump (1) according to any one of claims 1 to 4, wherein the concave surface has a curved cross section with a curved bottom when viewed in a cross-sectional plane passing vertically through the front surface (42).

12. Intravascular blood pump (1) according to any one of claims 1 to 4, wherein the concave surface has a triangular cross-section when viewed in a sectional plane passing vertically through the front surface (42).

13. An intravascular blood pump (1) according to any one of claims 1 to 4, wherein in the concave surface, 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) in the concave surface protrudes axially from a radially outer region of the front surface (42) in the concave surface.

14. Intravascular blood pump (1) according to any one of claims 1-4, wherein the concave surface opens towards a first side surface of the at least one of the posts (40), wherein the first side surface is radially outward relative to the axis of rotation (10).

15. An intravascular blood pump (1) according to claim 14, wherein at least one of the columns (40) has a triangular cross-section with three side surfaces, the three side surfaces including the first side surface, wherein the first side surface is radially outward relative to the rotation axis (10) compared to the other two of the three side surfaces.

16. Intravascular blood pump (1) according to any one of claims 1 to 4, wherein the concavity has a maximum depth between 0.05 mm and 0.3 mm.

17. An intravascular blood pump (1) according to any one of claims 2 to 4, wherein the at least one of the columns (40) has a longitudinal axis (LA) and a constant cross-section at least in the impeller-side end region of the at least one of the columns (40), so that its impeller-side end (420) extends radially no further than the impeller-side end (424) of the coil winding (44) arranged around the at least one of the columns (40), wherein the term radial relates to a direction transverse to the longitudinal axis (LA).

18. An intravascular blood pump (1) according to any one of claims 1, 3 and 4, wherein at least one of the columns comprises or consists of a discontinuous soft magnetic material, which is discontinuous in terms of conductivity in a cross section transverse to the longitudinal axis (LA) of the corresponding column (40) so as to provide at least one discontinuity in terms of conductivity in the discontinuous soft magnetic material.

19. An intravascular blood pump (1) according to claim 18, wherein at least one welding portion (82, 83, 86) is arranged on the surface (811) of the discontinuous soft magnetic material, and the welding portion (82, 83, 86) connects the at least one discontinuity in conductivity in the discontinuous soft magnetic material.

20. An intravascular blood pump (1) according to any one of claims 1, 2 and 4, wherein each of the columns (40) has a rear end portion (450), wherein the drive unit (4) includes a back plate (50) connecting the rear end portions (450) of the columns (40) and extending between the columns (40) in an intermediate region (59), wherein the material of at least one of the columns (40) is integral with the material of the intermediate region (59) of the back plate (50).

21. An intravascular blood pump (1) according to any one of claims 1 to 3, wherein each of the columns (40) has a rear end portion (450), wherein the drive unit (4) includes a back plate (50) connected to the rear end portions (450) of the columns (40), and wherein at least one of the rear end portions (450) of the columns (40) has a rear end surface (45) in contact with the back plate (50).

Images