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 flow inlet and a blood flow outlet and an impeller 3 arranged in the pump casing so as to rotate about a rotation axis 10. The impeller 3 has blades 31 which are sized and shaped for conveying blood from the blood flow inlet to the blood flow outlet. The blood pump includes a drive unit 4 for rotating the impeller 3, and the drive unit 4 includes a plurality of posts 40 arranged around the rotation axis 10 and a back plate 50. Coil winding 44 is arranged around each of the posts 40. The coil winding 44 is controllable so as to create a rotating magnetic field, and the impeller 3 includes a magnetic structure 32 arranged to interact with the rotating magnetic field so as to rotate the impeller 3. A rear end surface 45 of the post 40 is brought into contact with the back plate 50.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a blood pump, and more particularly, to an intravascular blood pump for assisting blood flow within a patient's blood vessel that is percutaneously inserted into the patient's blood vessel. This blood pump has an improved drive unit.

Background Art

[0002] Various types of blood pumps are known, such as axial flow blood pumps, centrifugal (i.e., radial flow) blood pumps, or hybrid blood pumps. A hybrid blood pump is a blood pump in which blood flow is caused by both axial and radial forces. An intravascular blood pump is inserted into a patient's blood vessel, such as the aorta, by a catheter. The blood pump typically includes a pump casing having a blood flow inlet and a blood flow outlet connected by a passage. To cause blood flow from the blood flow inlet to the blood flow outlet along this passage, an impeller or rotor is rotatably supported within the pump casing, and the impeller includes blades for carrying blood.

[0003] Blood pumps are typically driven by a drive unit. This drive unit can be an electric motor. For example, U.S. Patent Application Publication 2011 / 0238172A1 discloses an extracorporeal blood pump having an impeller that can be magnetically coupled to an electric motor. This impeller includes a magnet positioned next to a magnet in the electric motor. The rotation of the electric motor is transmitted to the impeller by the attractive force between the magnet in the impeller and the magnet in the electric motor. Also from U.S. Patent Application Publication 2011 / 0238172A1, it is known that a rotating magnetic field can be used to reduce the number of rotating parts. The drive unit has several stationary posts arranged around a rotating axis, each carrying a wire coil winding and acting as a magnetic core. A control unit sequentially supplies voltage to the coil winding to generate a rotating magnetic field. To provide a sufficiently strong magnetic coupling, the magnetic force must be sufficiently high. This can be achieved by supplying a sufficiently large current to the drive unit or by providing a large magnet. However, a large magnet leads to a large overall diameter for the blood pump.

[0004] European Patent No. 3222301B1 discloses a blood pump having a magnetic coupling between a drive unit and an impeller, in particular an intravascular blood pump having a magnetic coupling between a drive unit and an impeller, the blood pump having a compact design, in particular a large pumping power-to-size ratio, and as a result having sufficiently small external dimensions, or even smaller for handling and convenience reasons, that allow the blood pump to be inserted transvascularly, transvenously, transarterially or transvalvulsively.

[0005] More specifically, the blood pump of European Patent No. 3222301B1 comprises a pump casing having a blood inlet and a blood outlet, an impeller, and a drive unit for rotating the impeller. By rotating the impeller around a rotation axis inside the pump casing, blood can be transported from the blood inlet to the blood outlet by the blades of the impeller. The drive unit comprises a plurality of columns, preferably six columns, and a back plate connecting the rear ends of the columns, which act as a yoke. These columns are arranged in a circle around the rotation axis when viewed in a plane perpendicular to the rotation axis, and each of these columns has a longitudinal axis, preferably parallel to the rotation axis. Each of these columns has a shaft and a coil winding arranged around the column. The coil windings can be controlled in a coherent manner to generate a rotating magnetic field for driving the impeller. The impeller comprises a magnetic structure in the form of magnets arranged to interact with the rotating magnetic field so that the impeller follows the rotation of the rotating magnetic field. The backplate has through-openings into which the rear ends of the columns are received so as to fit snugly, such that the end faces of the rear ends of the columns are coplanar with the rear surface of the backplate. In this way, a magnetic connection is created between the columns and the backplate between the perimeter of the columns and the inner contour of the openings in the backplate.

[0006] The disadvantage of this structure is that the connection is either a loose fit, which does not provide a good mechanical connection between the column and the backplate and also imposes poor magnetic coupling, or a tight fit, which is thought to provide a good mechanical and magnetic coupling but requires the shape of the opening and the cross-section of the column to match precisely. Similarly, an intermediate fit requires precise tolerances, which increases its manufacturing cost. [Overview of the project] [Means for solving the problem]

[0007] The blood pump of the present invention corresponds to the blood pump described above. Accordingly, the blood pump of the present invention may be an axial-flow blood pump or a mixed-flow blood pump (the diameter of a pure centrifugal blood pump is usually too large for intravascular applications). A mixed-flow blood pump is a blood pump that pumps partially axially and partially radially. However, according to one aspect of the present invention, at least one column, preferably all columns, are in contact with the backplate at the corresponding rear end surface (hereinafter, rear end surface) of each column. This offers the advantage that the quality of the magnetic connection between the column and the backplate can be made independent of the quality of the mechanical fixation that secures the column to the backplate. For example, the column can be mechanically fixed to the backplate in a corresponding recess in the backplate or by an adhesive provided around the rear end of the column. In this way, a good magnetic connection, and therefore a good magnetic flux, can be directly achieved through the rear end surface of the column entering the backplate without being forced to accept constraints regarding the mechanical properties of the mechanical connection between the column and the backplate. Furthermore, a magnetic path for transmitting the magnetic flux is established. This magnetic path can exist in addition to the circumferential transmission of magnetic flux when the rear end of the column is received in a recess of a backplate of appropriate size.

[0008] According to the present invention, the rear end faces of at least one column, preferably all of the column rear end faces, can be positioned substantially perpendicular to the longitudinal axis of that at least one column. This at least one column, preferably all of the column, may further comprise a circumferential / peripheral surface extending along the longitudinal axis, arranged around the column's longitudinal axis, the rear end face being provided at the longitudinal rear end of the circumferential surface, and the rear end face facing away from the impeller. Preferably, the rear end face is substantially perpendicular to the circumferential surface.

[0009] Therefore, the column can be magnetically connected to the backplate at the corresponding contact plane of the backplate. Preferably, this contact plane is positioned parallel to the rear end face of the column. Preferably, this contact plane is positioned perpendicular to the axis of rotation. In any case, it is preferable that the entire surface area of ​​the rear end face of the column is in contact with the backplate. This significantly reduces the magnetic resistance of the connection between the column and the backplate. Preferably, the degree to which the contact plane of the rear end face and the backplate is not flat is such that the resulting gap is 10 μm or less.

[0010] Each column has a longitudinal axis. Preferably, the longitudinal axis of each column is parallel to the axis of rotation. Each column may contain a soft magnetic material that is discontinuous in a cross section that crosses the longitudinal axis of the corresponding column, preferably in a cross section perpendicular to the longitudinal axis of the corresponding column. In other words, the soft magnetic material of the column is discontinuous in a cross section that crosses the direction of the magnetic flux produced by the corresponding coil windings of the column, preferably in a cross section perpendicular to the direction of the magnetic flux produced by the corresponding coil windings of the column. Eddy currents in the column can be reduced or prevented in such a manner that heat generation and energy consumption can be reduced by dividing or interrupting the soft magnetic material in the cross section. Reducing energy consumption is particularly useful for long-term applications of blood pumps, where it is desirable for the blood pump to be battery-powered to provide mobility to the patient. Furthermore, in long-term applications, the blood pump can be operated without purging, which is only possible if the heat generation is small.

[0011] In the sense of this specification, “discontinuous” means that the soft magnetic material is interrupted, separated, or divided by an insulating material or other material or gap, when viewed in a cross-section across the longitudinal axis, in order to form strictly separated areas of the soft magnetic material or areas that are interrupted but connected at other locations.

[0012] Providing a discontinuous soft magnetic material in a cross-section across the direction of magnetic flux reduces eddy currents, and therefore heat generation and energy consumption, as described above. To avoid significantly weakening the magnetic field compared to a continuous or full-body (i.e., solid) soft magnetic material, the total amount of soft magnetic material is maximized while minimizing the continuous area of ​​soft magnetic material. This can be achieved, for example, by providing the soft magnetic material in the form of multiple sheets of a soft magnetic material such as electric steel. In particular, these sheets may form a stack of sheets. It is preferable that these sheets are electrically insulated from each other, for example, by providing an adhesive, lacquer, baking enamel, etc., between adjacent sheets. Such an arrangement can be described as "slotted." In such a manner that the magnetic field produced by the slotted columns is substantially the same as that produced by the solid columns, the amount of soft magnetic material is only slightly reduced compared to a full-body soft magnetic material, and the amount of insulating material is kept low. In other words, heat generation and energy consumption can be significantly reduced, while the loss of magnetic field due to the insulating material is minimal.

[0013] These plates are preferably arranged substantially parallel to the longitudinal axis of each corresponding column. In other words, these plates can be arranged substantially parallel to the direction of magnetic flux in such a manner that these columns are discontinuous in a cross-section transverse to the direction of magnetic flux or in a cross-section perpendicular to the direction of magnetic flux. It will be understood that these plates can be arranged obliquely to the longitudinal axis of each corresponding column, insofar as the soft magnetic material is discontinuous in a cross-section transverse to the longitudinal axis. These plates are preferably arranged in thickness in the range of 25 μm to about 1 mm, and more preferably in thickness in the range of 50 μm to 450 μm, for example, 200 μm.

[0014] It is commonly known that slotted soft magnetic materials, such as electrical steel, are placed inside electric motors to prevent or reduce eddy currents. However, this technique is applied to large devices where the plates typically have a thickness in the range of approximately 500 μm or more. In small applications such as the blood pump of the present invention, where a single column typically has a diameter of about the aforementioned size and the input power is relatively small (e.g., a maximum of 20 watts (W)), eddy currents and related problems were not anticipated. Surprisingly, despite the small diameter of the column, eddy currents can be reduced by providing a slotted column, and therefore heat generation and energy consumption can be reduced. This is advantageous for the operation of blood pumps, which may operate at high speeds of up to 50,000 rpm (revolutions per minute).

[0015] It will be understood that arrangements other than the slotted arrangement described above, which provide discontinuous soft magnetic material within the columns, may also be possible. For example, instead of multiple plates, multiple wires, fibers, columns, or other elongated elements can be used to form each column of the drive unit. These wires, etc., can be provided in the form of bundles in which the wires are electrically insulated from one another, for example, by a coating surrounding each wire or by an insulating matrix in which the wires are embedded, and can have various cross-sectional shapes such as circular, rounded, rectangular, square, and polygonal. Similarly, it is also possible to provide particles of soft magnetic material, wire wool or other spongy or porous structures of soft magnetic material in which the spaces between areas of soft magnetic material contain electrically insulating materials such as adhesives, lacquers, or polymer matrices. Sintered or pressed materials can also be used to form porous structures of soft magnetic material, and thus discontinuous structures of soft magnetic material. Since an insulating layer can be automatically formed by an oxide layer resulting from the oxidation of the soft magnetic material due to exposure to air, additional insulating material can be omitted in such structures.

[0016] The plates or other structures of the soft magnetic material can be uniformly formed, that is, the thickness of the plates in one column or all columns can be the same, or the diameter of the wires can be the same, but a non-uniform arrangement can also be provided. For example, the plates can have varying thicknesses, or the wires can have varying diameters. More specifically, with respect to a stack of plates, one or more plates in the center can have a greater thickness, and the adjacent plates can have a smaller thickness as you move towards the ends of the stack. That is, the thickness of the plates decreases from the center of the stack towards the ends, i.e., from the center of the stack towards the outermost plate. Similarly, one or more wires in the center of a bundle of wires can have a greater diameter, and the wires at the edges of the column can have a smaller diameter. That is, the diameter of the wires can decrease from the center of the bundle towards the edges, i.e., from the center of the bundle towards the outermost wire. With respect to a cross section across the longitudinal axis of the column, it may be advantageous to provide a larger continuous area of ​​soft magnetic material at the center of the column, i.e., to provide a relatively thick plate or a relatively thick wire at the center of the column. This is because it allows for the strengthening of the magnetic flux passing through the center along the vertical axis of each column, and the eddy currents in the center are less relevant than those in the lateral regions of the column. In other words, this arrangement can be advantageous because the eddy currents in the lateral regions of the column are more significant, and these eddy currents can be reduced by thin plates or wires in the lateral regions.

[0017] Similar to the columns, the backplate may also contain discontinuous soft magnetic material. Since the magnetic flux in the backplate substantially crosses or is substantially perpendicular to the axis of rotation, it is preferable that the soft magnetic material of the backplate be discontinuous in a cross-section parallel to the axis of rotation. In addition, substantially all of the features and descriptions above relating to the discontinuous material of the columns are also valid for the backplate. For example, like the columns, the backplate may also be slotted, i.e., the backplate may also be made of multiple stacked plates, and it is preferable that these plates of the backplate are electrically insulated from each other. The plates of the backplate may extend substantially perpendicular to the plates of the columns. As described above, eddy currents can be reduced, thereby reducing heat generation and power consumption. However, alternatively, the backplate may also be made of continuous soft magnetic material, i.e., solid soft magnetic material.

[0018] Similar to the columns, the backplate is preferably made of a soft magnetic material such as electrical steel (magnetic steel) or another material suitable for closing magnetic flux circuits, preferably cobalt steel. The diameter of the backplate can range from 3 mm to 9 mm, such as 5 mm or 6 mm to 7 mm. The thickness of the backplate can range from 0.5 mm to 2.5 mm, such as 1.5 mm. The outer diameter of the blood pump can range from 4 mm to 10 mm, preferably about 7 mm. The outer diameter of the arrangement of these multiple columns can range from 3 mm to 8 mm, such as 4 mm to 7.5 mm, preferably 6.5 mm.

[0019] As mentioned above, the columns are made of a soft magnetic material such as electrical steel (magnetic steel). The columns and backplate can be made of the same material. The drive unit, including the columns and backplate, is preferably made of cobalt steel. The use of cobalt steel contributes to reducing the pump size, especially the diameter. Because it has the highest permeability and the highest saturation magnetic flux density among all magnetic steels, cobalt steel produces the most magnetic flux when the same amount of material is used.

[0020] The backplate preferably has a recess into which the rear end of the column is inserted. Each column is in contact with the backplate at the bottom of the corresponding recess. In this case, magnetic flux can be transmitted around the column and through the rear end surface. Furthermore, in this arrangement, the column can be mechanically fixed to the backplate around its periphery.

[0021] The backplate preferably comprises at least two layers. The first layer may have a through hole into which the rear end of the column can be inserted, and this through hole preferably extends perpendicularly through the first layer. The second layer provides a contact plane into which the rear end face of the column makes contact. When stacked, these two layers together form the aforementioned recess at the location of the through hole in the first layer. The contact plane between the first and second layers preferably extends across the axis of rotation. If the backplate comprises the two layers described above, one or preferably both layers may contain the aforementioned discontinuous soft magnetic material, preferably in the form of a lamination of soft magnetic plates. Alternatively, the first and second layers may be electrically insulated from each other and each contain the soft magnetic material, and thus, when assembled together, form the discontinuous soft magnetic material of the backplate.

[0022] It is even more preferable that the cross-section of the recess matches, in terms of shape and size, the cross-section of the rear end of the column inserted into the recess. This enables a tight connection between the column and the backplate around the column, thereby allowing for proper mechanical connection of the rear end of the column and high magnetic flux passing around the rear end of the column.

[0023] The dimensions of the column, particularly its length and cross-sectional area, can vary and depend on various factors. In contrast to the dimensions of the blood pump, which depend on its application (e.g., the outer diameter of the blood pump), the dimensions of the column are determined by its electromagnetic properties, which are tuned to achieve the desired performance of the drive unit. One of these factors is the magnetic flux density achieved by the smallest cross-sectional area of ​​the column. A smaller cross-sectional area requires a larger current to achieve the desired magnetic flux. However, a larger current also generates more heat within the coil wire due to electrical resistance. This means that while a "thinner" column is preferable to reduce the overall size, thinner columns require a larger current, resulting in unwanted heat generation. The heat generated within the wire also depends on the length and diameter of the wire used for the coil winding. To minimize winding losses (called "copper losses" or "copper power losses" when copper wire is used, which is the usual case), shorter wire lengths and larger wire diameters are preferable. In other words, smaller wire diameters generate more heat for the same current compared to thicker wires. The preferred wire diameter is, for example, 0.5 mm to 0.2 mm, or 0.1 mm. Further factors affecting the dimensions of the pole and the performance of the drive unit are the number of coil windings and the outer diameter of the windings, i.e., the outer diameter of the pole containing the windings. A large number of windings can be arranged as two or more layers around each pole. For example, two or three layers can be provided. However, the more layers there are, the more heat is generated. This is because the length of the wires in the outer layers with larger winding diameters becomes longer. Longer wires can generate more heat due to their higher resistance compared to shorter wires. Therefore, a single winding layer with a small winding diameter is considered preferable. A typical number of windings, depending on the length of the pole, can be about 50 to about 150, for example, 56 or 132. Regardless of the number of windings, the coil windings are made of conductive material, especially metals, such as copper or silver. Silver is sometimes preferred over copper because its electrical resistance is about 5% lower than that of copper.

[0024] The above summary of the preferred embodiments and the following detailed description will be better understood when read in conjunction with the accompanying drawings. The drawings are referred to for the purpose of illustrating the disclosure. However, the scope of the disclosure is not limited to the specific embodiments disclosed in the drawings.

Brief Description of the Drawings

[0025] [Figure 1] It is a cross-sectional view of a blood pump. [Figure 2] It is a cross-sectional view of a first embodiment of a drive unit-impeller-arrangement. [Figure 3A] It is a perspective view showing a spacer for the drive unit-impeller-arrangement according to FIG. 2. [Figure 3B] It is a front view of the spacer of FIG. 3A. [Figure 3C] It is a side view of the spacers of FIGS. 3A and 3B. [Figure 4A] It is a perspective view of the first layer of a backplate having an opening for a pillar of the drive unit of the arrangement according to FIG. 2. [Figure 4B] It is a perspective view of the second layer of a backplate without an opening for a pillar of the drive unit of the arrangement of FIG. 2. [Figure 4C] It is a cross-sectional view of an assembled backplate including the first and second layers of FIGS. 4A and 4B. [Figure 5A] It is a view showing a stage of manufacturing an intermediate product for further manufacturing a pillar of the drive unit of the arrangement according to FIG. 2. [Figure 5B] It is a view showing a stage of manufacturing an intermediate product for further manufacturing a pillar of the drive unit of the arrangement according to FIG. 2. [Figure 5C] It is a view showing a stage of manufacturing an intermediate product for further manufacturing a pillar of the drive unit of the arrangement according to FIG. 2. [Figure 5D] It is a view showing a stage of manufacturing an intermediate product for further manufacturing a pillar of the drive unit of the arrangement according to FIG. 2. [Figure 6A]Figure 5C shows the weld on the intermediate product. [Figure 6B] Figure 5C shows the weld on the intermediate product. [Figure 6C] Figure 5C shows the weld on the intermediate product. [Figure 7] These are perspective views of columns cut from intermediate products prepared according to Figures 5A to 6C. [Figure 8] Figure 6A is a plan view of the intermediate product, which has two weld seams and two cross-sections of a column cut from the intermediate product. [Figure 9] This is a front view of the end face of a column having a welded joint. [Figure 10A] This figure shows cross-sections of columns according to various embodiments. [Figure 10B] This figure shows cross-sections of columns according to various embodiments. [Figure 10C] This figure shows cross-sections of columns according to various embodiments. [Figure 10D] This figure shows cross-sections of columns according to various embodiments. [Figure 10E] This figure shows cross-sections of columns according to various embodiments. [Figure 10F] This figure shows cross-sections of columns according to various embodiments. [Figure 10G] This figure shows cross-sections of columns according to various embodiments. [Figure 10H] This figure shows cross-sections of columns according to various embodiments. [Figure 10I] This figure shows cross-sections of columns according to various embodiments. [Figure 10J] This figure shows cross-sections of columns according to various embodiments. [Modes for carrying out the invention]

[0026] Referring to Figure 1, a cross-sectional view of the blood pump 1 is shown. The blood pump 1 comprises a pump casing 2 having a blood inlet 21 and a blood outlet 22. The blood pump 1 is designed as an intravascular pump, also called a catheter pump, and is deployed into the patient's blood vessels by a catheter 25. The blood inlet 21 is at the end of a flexible cannula 23, which can be positioned to penetrate a cardiac valve such as the aortic valve during use. The blood outlet 22 is located on the side of the pump casing 2 and can be positioned within a cardiovascular vessel such as the aorta. The blood pump 1 is electrically connected to a power line 26 extending within the catheter 25, which supplies power to the blood pump 1 to drive the pump 1 via a drive unit 4. This drive will be described in more detail later.

[0027] If the blood pump 1 is intended for long-term use, i.e., if it is intended to be used for several weeks or months while implanted in the patient, it is preferable that it be powered by a battery. This allows the patient to move around, as they are not connected to a base station by cables. The patient can carry the battery with them, and the battery can supply electrical energy to the blood pump 1, for example, wirelessly.

[0028] Blood is transported along a passage 24 connecting a blood inlet 21 and a blood outlet 22 (blood flow is indicated by arrows). An impeller 3 is provided to transport blood along the passage 24, and the impeller 3 is mounted within the pump casing 2 so as to be able to rotate around a rotating shaft 10 by means of a first bearing 11 and a second bearing 12. The rotating shaft 10 is preferably the longitudinal axis of the impeller 3. In this embodiment, both bearings 11 and 12 are contact bearings. However, at least one of the bearings 11 and 12 may be a non-contact bearing such as a magnetic bearing or a hydrodynamic bearing. The first bearing 11 is a pivot bearing having a spherical bearing surface that allows for some rotational and pivoting motion. A pin 15 is provided that forms one of the bearing surfaces. The second bearing 12 is positioned within a support member 13 to stabilize the rotation of the impeller 3, and the support member 13 has at least one opening 14 for blood flow. Blades 31 are provided on the impeller 3 to carry blood when the impeller 3 rotates. The rotation of the impeller 3 is caused by a drive unit 4 which is magnetically coupled to a magnet 32 ​​at the end of the impeller 3. The illustrated blood pump 1 is a mixed-type blood pump, and the main direction of flow is axial. Depending on the arrangement of the impeller 3, and especially the arrangement of the blades 31, the blood pump 1 can also be a purely axial blood pump.

[0029] 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, although only two of these columns 40 are shown in the cross-sectional view of Figure 1. The columns 40 are arranged parallel to the axis of rotation 10, and more specifically, the longitudinal axis of each column 40 is parallel to the axis of rotation 10. One end 420 of the column 40 is located next to the impeller. Coil windings 44 are arranged around the column 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 a power line 26. The impeller has a magnet 32, which in this embodiment is formed as a multi-piece magnet. The magnet 32 ​​is located at the end of the impeller 3 facing the drive unit 4. The magnet 32 ​​is arranged to interact with the rotating magnetic field so as to rotate the impeller 3 around the axis of rotation 10.

[0030] To close the magnetic flux path, a backplate 50 is placed at the end of column 40 on the side opposite to the impeller side of the column. Column 40 acts as a magnetic core and is made of a suitable material, in particular a soft magnetic material such as steel or a suitable alloy, the suitable alloy being cobalt steel in particular. Similarly, the backplate 50 is also made of a suitable soft magnetic material such as cobalt steel. The backplate 50 enhances the magnetic flux, and this enhancement of the magnetic flux allows for a reduction in the overall diameter of the blood pump 1, which is important for an intravascular blood pump. For the same purpose, a yoke 37, or additional impeller backplate, is provided within the impeller 3 on the side of the magnet 32 ​​facing away from the drive unit 4. The yoke 37 in this embodiment has a conical shape to guide blood flow along the impeller 3. The yoke 37 can also be made of cobalt steel. One or more wash-out channels extending toward the central bearing 11 may be formed within the yoke 37 or the magnet 32.

[0031] Figure 2 shows a cross-sectional view of a preferred embodiment of the drive unit-impeller arrangement of the blood pump according to Figure 1. As can be seen from Figure 2, the impeller-side end 420 of column 40 does not extend radially over the winding 44. Rather, the cross-section of column 40 is constant in the direction of the longitudinal axis LA of column 40. Thus, the columns 40 are prevented from coming into close proximity to each other. When the columns 40 come into close proximity to each other, partial magnetic short circuits can occur, resulting in a decrease in the power of the motor of the blood pump.

[0032] The drive unit shown in Figure 2 may comprise at least two, at least three, at least four, at least five, or preferably six columns 40. The number of columns 40 may be greater, such as nine or twelve. Because this is a cross-sectional view, only two columns 40 are shown. The columns 40 and the backplate 50 form the magnetic core 400 of the drive unit 4. The magnetic core 400 may have a diameter smaller than 10 mm.

[0033] As shown, the column 40 may be made of a discontinuous soft magnetic material that is discontinuous in terms of electrical conductivity. This discontinuous soft magnetic material includes a plurality of plates 85 made of ferromagnetic material that are laminated together. The direction of lamination is in the direction of the longitudinal axis LA of the column 40 and is indicated by the arrow DL. As shown, the column 40 is arranged parallel to the axis of rotation 10.

[0034] Spacers 7 are arranged around the column 40. The spacers 7 are made of a magnetically inert material, and their purpose is to maintain a constant distance of the column 40 at the impeller-side end 420. The spacers 7 will be described in more detail with reference to Figures 3A to 3C. The impeller-side end 424 of the coil winding 44 extends to the spacers 7. A back plate 50 is provided at the other end of the column 40. According to the embodiment shown in Figure 2, the back plate 50 has a recess for receiving the column 40 therein. More specifically, the back plate 50 comprises a first layer 51 having an opening 511 for receiving the rear end 450 of the column 40. The back plate 50 will be described in more detail with reference to Figures 4A to 4C.

[0035] It is conceivable to realize an embodiment of the blood pump 1 having any combination of the three features described above, namely, that the impeller-side end 424 of the column does not extend radially over the impeller-side end of the winding 44, that a magnetically inert spacer 7 is provided between the columns 40, and that the backplate 50 has a recess for receiving the rear end 450 of the column 40.

[0036] Figures 3A to 3C show a perspective view, front view, and side view of the spacer 7, respectively. The spacer 7 as a whole has the form of a disc or wheel with a through hole 75 in the center. The spacer 7 is provided with an opening 71 for each column. In the embodiment having six columns 40, there are six openings 71 as shown. Distancing spokes 72 are arranged between the openings 71. When the columns 40 are inserted into the openings 71, the distancing spokes 72 maintain a constant distance between the columns 40. Furthermore, the spacer 7 is provided with an outer rim 73 and an inner rim 74, which connect adjacent distancing spokes 72 and stabilize the spacer. The spacer 7 is made of titanium, a paramagnetic material, which prevents magnetic short circuits when placed between the impeller side ends 420 of the columns 40. Titanium provides high mechanical strength, which allows for the manufacture of spacer 7 with a small thickness. This is advantageous in terms of the consumption of structural space.

[0037] Figure 4A shows a perspective view of the first layer 51 of the backplate 50. The first layer 51 as a whole has the shape of a disc or wheel with a central hole 515. The first layer 52 includes an opening 511 into which the rear end 450 of the column 40 is placed. The first layer 51 includes distancing spokes 512 arranged between the openings 511. One purpose of the distancing spokes 512 is to keep the distance between the rear ends 450 of the column 40 constant. Furthermore, the first layer 51 includes an outer rim 513 and an inner rim 514, which connect the distancing spokes 512 at the outer radial end and inner radial end of the openings 511, respectively. The first layer 51 may be made of a discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity. The first layer 51 may consist of several ferromagnetic plates 85, in particular, of three plates as shown in Figure 4A. To form a discontinuous soft magnetic material, the plate 85 is laminated together with a non-conductive material. The lamination direction DL is generally parallel to the plate 85, and the direction in which the plate mainly expands defines the lamination surface. Within the back plate 50, the plate 85 is perpendicular to the axis of rotation 10. A hole 515 is located in the center of the first layer 51. The purpose of the hole 515 may be to facilitate the assembly of the first layer 51 and the second layer 52, for example, to facilitate the alignment of the first and second layers 51 and 52.

[0038] Figure 4B shows a perspective view of the second layer 52 of the backplate 50. The second layer 52 substantially has the form of a disc with a hole 525 in the center that coincides with the hole 515 of the first layer 51. The second layer 52 does not have an opening for the rear end of the column 40. Instead, the second layer 52 has a contact plane 526 that faces the rear end 450 of the column 40. In the assembled drive unit, the rear end 450 of the column 40 is in contact with the contact plane 526 of the second layer 52 of the backplate 50 in order to transmit magnetic flux between the rear end 450 of the column 40 and the backplate 50. Because all the rear ends 450 of the column 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 within the second layer 52. To enable this, the second layer 52 is made of a soft magnetic material. This soft magnetic material can be a discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity, and may include laminated plates 85, similar to the structure described above with respect to the first layer 51. For example, as shown in Figure 4B, three plates 85 may constitute the second layer 52. In the second layer 52, the lamination direction DL is perpendicular to the axis of rotation 10. The plates 85 are ferromagnetic and conductive, while the unspecified intermediate layers between the plates 85 are non-ferromagnetic and non-conductive. This type of discontinuous soft magnetic material reduces eddy currents that would otherwise be generated in much larger quantities by changes in magnetic flux. The purpose of the central hole 525 in the second layer 52 may be to facilitate the assembly of the first layer 51 and the second layer 52, for example, to facilitate the alignment of the first and second layers 51 and 52.

[0039] Figure 4C shows a cross-sectional view of the backplate 50. The backplate 50 consists of a first layer 51 and a second layer 52, which are joined to each other at the main surface of their respective layers that have the greatest extent. This joint between the first layer 51 and the second layer 52 of the backplate 50 can be established in the same manner as the joint between the plates 85 of the first and second layers 51 and 52. The through holes 515 in the first layer 51 and the through holes 525 in the second layer 52 are aligned to center the first layer 51 and the second layer 52. By stacking the first layer 51 and the second layer 52, one end of the opening 511 is closed by the second layer 52 in such a way that a recess 501 for accommodating the rear end 450 of the column 40 is formed. A contact plane 526 is formed at the bottom of the recess 501. When the column 40 is inserted into the recess 501, the rear end 450 of the column 40 comes into contact with the contact plane 526. Furthermore, the position of the column 40 is fixed by the distancing spokes 512 and the outer and inner rims 513, 514 that surround each column 40 together. In this way, a magnetic connection is established between the second layer 52 and the rear end surface 45 of the column 40 at the contact plane 526, and a second magnetic connection is established between the column 40 and the aforementioned portion of the first layer 51 surrounding the column 40. However, the main portion of the magnetic flux is transmitted through the contact plane 526. Preferably, the surface of the rear end 450 of the column 40 has a certain evenness, and preferably the contact plane 526 also has a certain evenness. In this way, the gap between the surface 45 of the rear end 450 of the column 40 and the contact plane 526 can be kept smaller than a certain size, preferably smaller than 10 μm. This improves the transmission of magnetic flux between the column 40 and the backplate 50. Preferably, there is no additional material between the surface 45 of the rear end 450 of the column 40 and the contact plane 526. In this embodiment of the present invention, the transmission of magnetic flux through the surface 45 and the backplate 50 is independent of the method of fixing the column 40 to the backplate 50.

[0040] Figures 5A to 5D show the preparation steps for producing column 40. Figure 5A shows a perspective view of plate 8 of discontinuous soft magnetic material, which is discontinuous in terms of electrical conductivity. Plate 8 will hereafter be referred to as the workpiece.

[0041] In Figure 5A, the plate 8 shows a width W from which the workpiece rod 81 is separated. The width W of the workpiece rod 81 is the same as the length of the column 40 produced from the workpiece rod 81. A magnified view of the portion indicated by the rectangle R in Figure 5A is shown in Figure 5B. This figure shows stacked plates 85 of discontinuous soft magnetic material. The stacking direction DL runs along the main plane of the plate 8, and therefore the stacking direction DL forms the stacked surface.

[0042] Figure 5C shows the workpiece rod 81 separated from plate 8 as a discontinuous piece of material. A magnified view of the portion indicated by rectangle R in Figure 5C is shown in Figure 5D. This magnified view shows the plate 85 of the workpiece rod 81.

[0043] Figure 6A shows the workpiece rod 81 from Figures 5C and 5D, which forms the basis for the welding step in preparing to cut out the column 40 from the rod 81. On the left-facing side of the rod 81 in Figure 6A, several cross-sections 84 of the column 40 to be manufactured from the rod 81 are shown. The column 40 is manufactured by cutting out these cross-sections 84 from the rod 81. Since the width W of the rod 81 matches the length of the column 40, the sides 811 and 812 of the rod 81 become the end faces of the impeller-side end 420 and the rear end 450 of the column 40.

[0044] Figure 6B shows the next preparation step before cutting out the columns 40. Two weld seams 82 and 83 are welded to the face 811 of the rod 81, spaced apart from each other, across the respective cross-sections 84 of the columns 40 to be cut out. The weld seams 82 and 83 run perpendicular to the lamination direction DL of the plates 85. In this way, the plates of discontinuous material are connected to each other. A single weld seam can be provided instead of two weld seams. Furthermore, a similar weld seam can be provided on the opposite face 812 of the rod 81. The presence of the weld seams 82 and 83 gives the plates 85 better mechanical and electrical connections to each other. This electrical connection has the advantage that current can flow from any point in the discontinuous soft magnetic material that is to become the columns 40 to each electrical connection point on the rod 81, which may be required for electrical discharge machining, for example. In this way, electrical discharge machining is made considerably easier. Furthermore, higher machining reliability is achieved because the cut columns 40 do not fall apart due to lamination delamination. Laser welding is preferred. Applying welding power to the same weld area two or more times may be advantageous. A portion of rod 81, indicated by rectangle R, is shown in an enlarged view in Figure 6C.

[0045] Therefore, Figure 6C shows multiple cross-sections 84 of the column 40 cut from the rod 81. The cross-sections 84 have a substantially triangular shape. The corners can be rounded as shown. The convex side 842 of the triangle shown on the left side of the cross-section 84 in Figure 6C has a convex shape. This type of cross-section 84 is advantageous for making full use of the available structural 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 lamination direction DL. In this way, the plate 85 runs symmetrically through the cross-section 84.

[0046] Figure 7 shows a column 40 cut from a rod 81. As shown on the surface 45 of the rear end 450 of the rod 81, weld seams 82 and 83 are still present on this surface. The column 40 has a constant cross-section 84 along its entire length. The weld seams 82 and 83 are removed after the column 40 is cut.

[0047] Figure 8 shows an alternative arrangement of two cross-sections 84 on a side 811 of a workpiece rod 81. In contrast to the workpiece rod 81 shown in Figures 6A to 6C, the side 811 of the workpiece rod 81 in Figure 8 is sized to allow the two cross-sections 84 to be placed side by side perpendicular to the stacking direction DL. The cross-sections 84 are oriented such that the bisector B of the opposite corner of the corresponding convex side 842 of each cross-section 84 aligns with the stacking direction DL. Arranging the cross-sections 84 along the rod 81 in this way can save material. Less waste is generated. Depending on the thickness of the rod 81 and the required cross-sectional dimensions of the column 40, it may also be possible to stack more cross-sections 84 of the column 40 perpendicular to the stacking direction DL. The weld seams 82 and 83 run across each of the respective cross-sections 84. The weld seams 82 and 83 also run across the entire side 811 of the rod 81 perpendicular to the stacking direction DL. In this way, all the discontinuous plates 85 of the soft magnetic material of the rod 81 are connected to one another.

[0048] Figure 9 shows an example of a column 40 cut from a welded rod 81, specifically a front view of one end face of the column 40 cut from the welded rod 81. As shown in Figure 9, a single weld seam 86 of considerable width runs along the convex side 842 of the cross section 84. The weld seam 86 may cover more than about one-third of the height of the triangular cross section 84. The weld seam 86 runs perpendicular to the lamination direction DL to connect all the plates of the column 40. In this case as well, the bisector B of the opposite corner 841 of the convex side 842 is aligned with the lamination direction DL.

[0049] Figures 10A to 10J show cross-sections of various embodiments of the column. Figures 10A to 10D show embodiments in which the column is slotted, i.e., embodiments in which the column is formed from multiple plates 171 insulated from each other by an insulating layer 172. The insulating layer 172 may include adhesives, lacquers, baked enamels, etc. Figures 10A and 10B show embodiments in which the thickness of the plates 171 is uniform. This thickness can range from 25 μm to 450 μm. The plate 171 shown in Figure 10A has a greater thickness than the plate 171 shown in Figure 10B. The plates in Figure 10C have different thicknesses, with the central plate being the thickest and the outermost plate being the thinnest. This can be advantageous because eddy currents are more significant in the lateral regions of the column, and thinner plates can reduce these eddy currents. Eddy currents in the central area are not as significant as those in the lateral regions, and the relatively thicker central plate can help improve the magnetic flux. As illustrated in Figure 10D, the orientation of the plate 171 can be different insofar as the soft magnetic material in the shown cross-section, i.e., the soft magnetic material in the cross-section that crosses the direction of the magnetic flux, is discontinuous or interrupted.

[0050] Figures 10E and 10F show embodiments in which a column 141 is formed by bundles of wires 181 insulated from one another by an insulating material 182. The insulating material 182 can be present as a coating on each wire 181, or as a matrix in which the wires 181 are embedded. In the embodiment of Figure 10E, all wires have the same diameter, while in the embodiment of Figure 10F, the central wire has the largest diameter and the outer wires have smaller diameters, similar to the embodiment shown in Figure 10C where the plate thicknesses differ. Wires 181 of different diameters can also be mixed, as shown in Figure 10G, which increases the total cross-sectional area of ​​the soft magnetic material compared to embodiments in which all wires have the same diameter. Alternatively, to further minimize the insulating layer 184 between the wires 183, the wires 183 can have polygonal cross-sectional areas such as rectangles or squares.

[0051] Alternatively, the discontinuous cross-section of the column 141 can be formed by metal particles 185 embedded in a polymer matrix 186 as shown in Figure 10I, or by steel wool or other porous structure impregnated with an insulating matrix. A porous structure of soft magnetic material, and therefore a discontinuous structure of soft magnetic material, can also be produced by a sintering process or a high-pressure molding process. In this case, an insulating layer is automatically formed by oxidation of the soft magnetic material due to exposure to air, so an insulating matrix can be omitted. Alternatively, the column 141 can be formed from a rolled plate 187 of soft magnetic material, where the layers of the rolled plate 187 are separated by an insulating layer 188 as shown in Figure 10J. This also provides a discontinuous cross-section in the sense of the present invention, which reduces eddy currents in the column 141 or column 40.

Claims

1. In an intravascular blood pump (1) that is inserted percutaneously into a patient's blood vessel, A pump casing (2) having a blood inlet (21) and a blood outlet (22), An impeller (3) is disposed within the pump casing (2) so as to be able to rotate around a rotating shaft (10), and the impeller (3) has blades (31) whose size and shape are determined to transport blood from the blood inlet (21) to the blood outlet (22), The drive unit (4) rotates the impeller (3) and comprises a plurality of columns (40) arranged around the rotation shaft (10) and a back plate (50) connecting the rear ends (450) of the columns (40). Each of the aforementioned columns (40) is surrounded by a coil winding (44), and the coil winding (44) is controllable to generate a rotating magnetic field. Equipped with, The impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field so as to rotate the impeller (3). Intravascular blood pump (1), Characterized by spacers (7) configured to maintain a constant distance between the impeller-side ends (420) of at least two of the columns (40), The intravascular blood pump (1) is characterized in that the spacer (7) has the shape of a disc having an opening (71) that receives at least two of the columns (40) of the column (40).

2. An intravascular blood pump (1) according to claim 1, characterized in that each of the openings (71) has a shape that coincides with the cross-section (84) of each corresponding column (40) among the at least two columns (40) of the column (40).

3. An intravascular blood pump (1) according to claim 1 or 2, characterized in that the spacer (7) is made of a magnetically inert material.

4. An intravascular blood pump (1) according to claim 3, characterized in that the spacer (7) is made of titanium.

5. An intravascular blood pump (1) according to any one of claims 1 to 4, characterized in that the spacer (7) is positioned at the impeller-side ends (420) of at least two of the columns (40) among the columns (40).

6. An intravascular blood pump (1) according to any one of claims 1 to 5, characterized in that the impeller-side end of the coil winding (44) extends to the spacer (7).

7. An intravascular blood pump (1) according to claim 6, characterized in that at least one of the columns (40) includes or is made of a soft magnetic material that is discontinuous in terms of electrical conductivity in a cross section that crosses the longitudinal axis (LA) of the at least one column (40).

8. An intravascular blood pump (1) according to claim 7, wherein at least one of the columns (40) comprises or is made of a discontinuous soft magnetic material that is discontinuous with respect to electrical insulation in a discontinuous direction, and the direction of the discontinuity is in a direction that crosses the rotation axis (10).

9. An intravascular blood pump (1) according to any one of claims 1 to 8, characterized in that the rear end (450) of at least one of the columns (40) has a rear end surface (45) that is in contact with the back plate (50).

10. An intravascular blood pump (1) according to any one of claims 1 to 9, characterized in that the back plate (50) has a recess (501) into which the rear end (450) of at least one of the columns (40) is inserted.

11. An intravascular blood pump (1) according to claim 10, characterized in that at least one of the columns (40) is in contact with the back plate (50) at the bottom of the recess (501).

12. An intravascular blood pump (1) according to claim 10 or 11, wherein the backplate (50) comprises at least two layers (51, 52) that together form the recess (510), the at least two layers (51, 52) comprising a first layer (51) having a through hole (511) into which at least one of the columns (40) is inserted, and a second layer (52) in contact with the rear end surface (45) of at least one of the columns (40).

13. An intravascular blood pump (1) according to claim 12, characterized in that a connecting plane (526) disposed between the first layer (51) and the second layer (52) extends across the rotation axis (10).

14. An intravascular blood pump (1) according to any one of claims 10 to 13, characterized in that the cross-section of the recess (501) corresponds in terms of shape and size to the cross-section (84) of the rear end (450) of at least one of the columns (40) that is inserted into the recess (501).

15. An intravascular blood pump (1) according to any one of claims 1 to 14, characterized in that the back plate (50) includes a laminated plate (85) of a soft magnetic material.

16. An intravascular blood pump (1) according to claim 15, characterized in that the plate (85) made of soft magnetic material is oriented perpendicular to the rotation axis (10).

17. An intravascular blood pump (1) according to any one of claims 1 to 16, characterized in that at least one of the columns (40) includes a laminated plate (85) of a soft magnetic material.

18. An intravascular blood pump (1) according to claim 17, characterized in that the plate (85) made of laminated soft magnetic material is oriented parallel to the vertical axis (LA) of at least one of the columns (40).

19. An intravascular blood pump (1) according to any one of claims 15 to 18, characterized in that the thickness of at least one of the plates (85) made of soft magnetic material is between 25 μm and 1 mm.

20. An intravascular blood pump (1) according to any one of claims 15 to 18, characterized in that the thickness of at least one of the plates (85) made of soft magnetic material is between 50 and 400 μm.

21. An intravascular blood pump (1) according to any one of claims 15 to 18, characterized in that at least one of the plates (85) made of soft magnetic material has a thickness of 200 μm.

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