blood pump
Patent Information
- Authority / Receiving Office
- KR · KR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2020-03-13
- Publication Date
- 2026-08-12
Smart Images
Figure R1020217032149_ABST
Abstract
Description
Technology Field
[0001] The present invention relates to a blood pump, in particular to an intravascular blood pump for percutaneous insertion into a patient's blood vessel to support blood flow within the patient's blood vessel. The blood pump has an enhanced driving unit. Background Technology
[0002] Various types of blood pumps are known, such as axial blood pumps, centrifugal (i.e., radial) blood pumps, or mixed blood pumps (where blood flow is driven by both axial and radial forces). Intravascular blood pumps are inserted into a patient's blood vessel, such as the aorta, via a catheter. A blood pump typically comprises a pump casing having a blood flow inlet and a blood flow outlet connected by a passage. To induce blood flow from the blood flow inlet to the blood flow outlet along the passage, an impeller or rotor is rotatably supported within the pump casing, and the impeller is provided with blades to transport the blood.
[0003] Blood pumps are generally driven by a drive unit, which may be an electric motor. For example, U.S. Patent Application Publication US 2011 / 0238172 A1 discloses an in vitro blood pump having an impeller that can be magnetically coupled to an electric motor. The impeller includes a magnet positioned adjacent to the magnet of the electric motor. Due to the attractive force between the magnet of the impeller and the magnet of the motor, the rotation of the motor is transmitted to the impeller. To reduce the number of rotating parts, utilizing a rotating magnetic field is also known from U.S. Patent Application Publication US 2011 / 0238172 A1, having a plurality of static posts arranged around the rotational axis of the drive unit, each post having a wire coil winding and acting as a magnetic core. A control device generates a rotating magnetic field by sequentially supplying voltage to the coil winding. To provide sufficiently strong magnetic coupling, the magnetic force must be sufficiently high, which can be achieved by supplying a sufficiently high current to the drive unit or by providing a large magnet, but this leads to a large overall diameter of the blood pump.
[0004] European patent EP 3222301 B1 discloses a blood pump, in particular an intravascular blood pump, which has magnetic coupling between a driving unit and an impeller, and the blood pump has a compact design and, in particular, a high ratio of pumping power to the size of the pump, which results in the blood pump having sufficiently small external dimensions so that it can be inserted through a blood vessel, through a vein, through an artery, or through a valve, and can be made much smaller for reasons of handling and convenience.
[0005] More specifically, the blood pump of European Patent EP 3222301 B1 comprises a pump casing having a blood flow inlet and a blood flow outlet, an impeller, and a drive unit for rotating the impeller. By rotating the impeller around a rotation axis within the pump casing, blood can be transported from the blood flow inlet to the blood flow outlet by the blades of the impeller. The drive unit comprises a plurality of preferably six posts and a backplate connecting the rear ends of the posts to act as a yoke. The posts are arranged in a circle around the rotation axis when viewed in a plane perpendicular to the rotation axis, and each post preferably has a longitudinal axis parallel to said rotation axis. Each post has a shaft and a head portion inclined at the rear end to the impeller-side end of the opposite shaft, and the head portion extends radially over the shaft to form a shoulder that can act as an axial stop for a coil winding disposed around each post. To generate a rotating magnetic field to drive the impeller, the coil windings can be controlled in a coherent manner. The impeller includes a magnetic structure in the form of magnets arranged to interact with the rotating magnetic field so that the impeller follows the rotation.
[0006] A disadvantage of the present technology is that the head portions extending radially over the shaft have a small distance from each other. The result is that there is significant parasitic magnetic flux between the head portions, which is lost for torque generation. In this regard, it is the objective of the present invention to improve the drive unit. means of solving the problem
[0007] The blood pump of the present invention corresponds to the blood pump described above. Thus, it may be an axial blood pump or a diagonal blood pump (this pump pumps partly axially and partly radially) (the diameter of a pure centrifugal blood pump is generally too large for intravascular application). However, according to one embodiment of the present invention, at least one of the posts, preferably each of the posts, does not extend such that the impeller-side end of at least one of the posts extends radially over the impeller-side end of the coil winding, and the term “radially” refers to a direction across the longitudinal axis of each post, preferably perpendicular to the longitudinal axis. In other words, the posts do not have a specific head portion. Instead, the posts preferably have a constant cross-section at least in the impeller-side end region, more preferably along the entire length.
[0008] During operation, adjacent posts generally have different magnetizations such that magnetic flux tends to flow between them, bypassing the impeller. This magnetic flow is lost to generate torque. The advantage of this type of post without a head section is that magnetic loss between adjacent posts is reduced by the greater distance between the posts. As a result, the ratio of torque to axial force between the drive unit and the impeller can be increased compared to a pump equipped with posts where the impeller-side ends extend radially over the impeller-side ends of each coil winding.
[0009] It is desirable for the impeller-side end of the post to have a flat shape. In particular, the impeller-side end is oriented perpendicular to the axis of rotation. The flat impeller-side end of the post has the effect of reducing the configuration space. This is because the surface of the impeller facing the post can also be flat. Consequently, the impeller can have a shorter overall length in the direction of the axis of rotation.
[0010] Preferably, the drive unit includes spacers for at least two, preferably all, of the posts. In particular, the spacers are configured to maintain a constant distance between the impeller-side ends of at least two posts. These two posts may be adjacent posts, but they may also be non-adjacent posts. In the latter case, the spacers may transmit force between the different posts, for example, through a rotational axis. In the case of adjacent posts, the spacers may fill the space between the posts. However, it is most desirable for all posts to be maintained at a constant distance from each other.
[0011] The spacer may be a disc. The disc may have an opening to insert the post into the opening. Forces between the posts can be transmitted through the boundaries of this opening. It is preferable for the disc-type spacer to have a thin thickness along the rotational axis. For example, the thickness may be 0.05 to 0.3 mm, preferably 0.066 to 0.2 mm, and more preferably approximately or exactly 0.1 mm. The thin thickness provides the advantage that almost no axial space is used for maintaining the distance. It is more preferable for the spacer to be made of a non-ferromagnetic material to avoid magnetic short circuits. Preferably, the spacer is made of titanium or other biocompatible materials. Titanium is preferred for its high mechanical strength to enable a thin thickness of the spacer.
[0012] Preferably, the coil winding is arranged on the side of the spacer facing away from the impeller. The impeller-side end of the coil winding may be arranged close to or in contact with the spacer. The spacer may be arranged on the impeller-side end of the post, preferably in a uniform manner with the flat surface of the impeller-side end of the post. By taking these measures, the utilization of available space inside the pump casing is improved.
[0013] Alternatively, the spacer may not be placed at the impeller-side end of the post or may be omitted. In the latter case, the impeller-side end of the coil winding may extend to the impeller-side end of each post. Then, the coil winding can generate magnetic force up to the impeller-side end of the post.
[0014] Each post has a longitudinal axis. Preferably, the longitudinal axis of each post is parallel to the axis of rotation. Each post comprises a discontinuous soft magnetic material in a cross-section that crosses the longitudinal axis of each post, preferably perpendicular thereto. In other words, the soft magnetic material of the post is discontinuous in a cross-section that crosses, preferably perpendicular to, the direction of the magnetic flux induced by each coil winding in the post. By dividing or interrupting the soft magnetic material in the cross-section, eddy currents in the post can be reduced or avoided, thereby reducing heat generation and energy consumption. Reducing energy consumption is particularly useful for long-term application of the blood pump, where it is preferable for the blood pump to be battery-powered to provide mobility to the patient. Additionally, during long-term application, the blood pump can be operated without purging, which is possible only when heat generation is low.
[0015] In the sense of this document, "discontinuous" means that a soft magnetic material visible in any cross-section across a longitudinal axis is interrupted, separated, or crossed by an insulating material or other material or gap to form strictly separated regions of the soft magnetic material or regions that are interrupted but connected at other locations.
[0016] Providing discontinuous soft magnetic material in a cross-section across the direction of the magnetic flux reduces eddy currents, as described above, and thus reduces heat generation and energy consumption. Compared to 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 the soft magnetic material so as not to significantly weaken the magnetic field. This can be achieved by providing the soft magnetic material in the form of multiple sheets of soft magnetic material, for example, electrical steel. In particular, the sheets can form a laminate of sheets. The sheets are preferably electrically insulated from one another, for example, by providing an adhesive, lacquer, or baking enamel between adjacent sheets. This arrangement can be indicated as "slotted." Compared to full-body soft magnetic material, the amount of soft magnetic material is reduced only slightly, and the amount of insulating material is kept small, so that the magnetic field induced by the slotted posts is substantially the same as the magnetic field induced by the solid posts. In other words, heat generation and energy consumption can be significantly reduced, but the magnetic field loss caused by the insulating material is negligible.
[0017] The sheet preferably extends substantially parallel to the longitudinal axis of each post. In other words, the sheet may extend substantially parallel to the direction of the magnetic flux, so that the post is discontinuous in a cross-section that crosses or is perpendicular to the direction of the magnetic flux. It will be understood that the sheet may extend at a certain angle to the longitudinal axis of each post, provided that the soft magnetic material is discontinuous in a cross-section that crosses the longitudinal axis. The sheet preferably has a thickness of, for example, 200 µm, within the range of 25 µm to 1 mm, more preferably 50 µm to 450 µm.
[0018] Generally, it is known to provide slotted soft magnetic materials, such as electric steel, to electric motors to avoid or reduce eddy currents. However, this technique has been applied to large devices where the sheet thickness typically ranges from about 500 μm or more. In small applications, such as the blood pump of the present invention, where one of the posts typically has a diameter of the aforementioned size and the power input is relatively low (e.g., up to 20 watts (W)), eddy currents and associated problems were not anticipated. Surprisingly, despite the small diameter of the posts, eddy currents and, consequently, heat generation and energy consumption can be reduced by providing slotted posts. This is advantageous for the operation of blood pumps that can operate at high speeds of up to 50,000 rpm (revolutions per minute).
[0019] It will be understood that arrangements other than the aforementioned slotted arrangements may be possible to provide discontinuous soft magnetic material to the posts. For example, instead of multiple sheets, multiple wires, fibers, posts, or other elongated elements may be provided to form each post of the drive unit. Wires, etc., may be provided in a bundle form, for example, in which the wires are electrically insulated from one another by a coating surrounding each wire or an insulating matrix in which the wires are embedded, and may have various cross-sectional shapes such as circular, round, rectangular, square, polygonal, etc. Likewise, particles of soft magnetic material, wire wool, or other sponge-like or porous structures of soft magnetic material may be provided, and the spaces between regions of the soft magnetic material contain electrical insulating materials such as adhesives, lacquers, polymer matrices, etc. The porosity and thus discontinuous structure of the soft magnetic material may also be formed by sintered materials or compressed materials. In this structure, additional insulating material can be omitted because the insulating layer can be automatically formed by an oxide layer resulting from the oxidation of the soft magnetic material due to exposure to air.
[0020] Sheets or other structures of soft magnetic material may be formed uniformly, meaning that sheets within one or all of the posts may have the same thickness or wires may have the same diameter, but a non-uniform arrangement may be provided. For example, sheets may have varying thicknesses, and wires may have varying diameters. More specifically, particularly with respect to a laminate of sheets, one or more central sheets may have a greater thickness, while sheets adjacent toward the ends of the laminate may have a smaller thickness. That is, the thickness of the sheets decreases from the center of the laminate toward the ends, i.e., toward the outermost sheets of the laminate. Similarly, one or more central wires in a bundle of wires may have a larger diameter, while wires at the edges of the posts may have a smaller diameter. That is, the diameter of the wires may decrease from the center toward the edges of the bundle, toward the outermost wires of the bundle. Providing a larger continuous area of soft magnetic material in the center of the post, that is, a relatively thick sheet or wire in the center, for a cross-section across the longitudinal axis of the post, can be advantageous because this can enhance the magnetic flux passing through the center along the longitudinal axis of each post, and the eddy currents in the center are less relevant than the eddy currents in the sides of the post. In other words, this arrangement can be advantageous because the eddy currents in the side regions of the post are more significant and can be reduced by the thin sheet or wire in the side regions.
[0021] The drive unit may include a backplate connecting the rear end of the posts. Preferably, the rear end surface of at least one post and preferably all posts among the posts is arranged substantially perpendicular to the longitudinal axis of at least one post among the posts. At least one post and preferably all posts among the posts may further include a circumferential / peripheral surface arranged around the longitudinal axis and extending along the longitudinal axis, the rear end surface being provided at the rear longitudinal end of said circumferential surface, and the rear end surface is directed away from the impeller. Preferably, the rear end surface is substantially perpendicular to the circumferential surface.
[0022] As with the post, the backplate may comprise a discontinuous soft magnetic material. Since the magnetic flux in the backplate is substantially transverse to or perpendicular to the axis of rotation, the soft magnetic material of the backplate is preferably discontinuous in a cross-section parallel to the axis of rotation. Except for this, substantially all features and descriptions mentioned above regarding the discontinuous material of the post are also valid for the backplate. For example, as with the post, the backplate may be slotted, that is, formed from a plurality of laminated sheets, and the sheets of the backplate are preferably electrically insulated from one another. The sheets of the backplate may extend substantially perpendicularly to the sheets of the post. As described above, eddy currents and the consequent heat generation and power consumption can be reduced. However, the backplate may alternatively be formed from a continuous, i.e., solid, soft magnetic material.
[0023] Like the posts, the backplate is preferably made of electric steel (magnetic steel) or other material suitable for closing the magnetic flux circuit, preferably a soft magnetic material such as cobalt steel. The diameter of the backplate may be within the range of 3 mm to 9 mm, such as 5 mm or 6 mm to 7 mm. The thickness of the backplate may be within the range of 0.5 mm to 2.5 mm, for example, 1.5 mm. The outer diameter of the blood pump may be within the range of 4 mm to 10 mm, preferably 7 mm. The outer diameter of the array of multiple posts may be within the range of 3 mm to 8 mm, for example, 4 mm to 7.5 mm, preferably 6.5 mm.
[0024] As described above, the post is made of a soft magnetic material such as electric steel (magnetic steel). The post and backplate may be made of the same material. Preferably, the drive unit, including the post and backplate, is made of cobalt steel. The use of cobalt steel contributes to reducing the pump size, particularly the diameter. Cobalt steel, having the highest permeability and the highest magnetic saturation flux density among all magnetic steels, generates the most magnetic flux for the same amount of material used.
[0025] The dimensions of the post, particularly its length and cross-sectional area, can vary and depend on various factors. Unlike the outer diameter, which depends on the application of the blood pump, for example, the dimensions of the post are determined by electromagnetic properties and are adjusted to achieve the desired performance of the drive unit. One of these factors is the magnetic flux density that must be achieved through the smallest cross-sectional area of the post. The smaller the cross-sectional area, the greater the current required to achieve the desired magnetic flux. However, a larger current generates more heat in the coil wire due to electrical resistance. This means that while "thin" posts are preferred to reduce the overall size, this requires high current, which consequently generates unwanted heat. The heat generated in the wire also depends on the length and diameter of the wire used for the coil winding. Short wire lengths and large wire diameters are preferred to minimize winding losses (generally referred to as "copper losses" or "copper power losses" when copper wire is used). In other words, a smaller wire diameter generates more heat compared to a thicker wire at the same current, and the preferred wire diameter is, for example, 0.05 mm to 0.2 mm, or 0.1 mm. Additional factors affecting the post dimensions and the performance of the drive unit are the number of coil windings and the outer diameter of the post containing the windings. Multiple windings can be arranged in one or more layers around each post; for example, two or three layers may be provided. However, the more layers there are, the more heat will be generated in the outer layers with larger winding diameters due to the increased length of the wire. The increased length of the wire can generate more heat because the resistance of the long wire is higher than that of the short wire. Therefore, a single layer of winding with a small winding diameter is preferred.The typical number of turns, which varies depending on the length of the post, can be about 50 to about 150, for example, 56 or 132. Regardless of the number of turns, the coil windings are made of an electrically conductive material, particularly a metal such as copper or silver. Silver may be preferred over copper because it has an electrical resistance about 5% lower than that of copper.
[0026] Preferably, at least one post, and more preferably each post, has a triangular cross-section that crosses the longitudinal axis of the post. Preferably, the cross-section of the post is triangular over the entire length of the post. Since the triangular posts can be densely packed around the axis of rotation, a high proportion of the usable space inside the pump housing can be utilized. Preferably, one side of the triangular faces is curved and directed away from the axis of rotation. The curvature is curved around the axis of rotation. The radius of the curvature preferably corresponds to the radius of the outer radius defined by a plurality of posts arranged around the axis of rotation. Through this curvature, further increase in the use of the internal space of the cylindrical pump housing can be achieved. Brief explanation of the drawing
[0027] The summary foregoing, as well as the following detailed description of preferred embodiments, will be better understood when read together with the accompanying drawings. The drawings are referenced to illustrate the present disclosure. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the drawings. In the drawings: Figure 1 shows a cross-sectional view of a blood pump. FIG. 2 shows a cross-sectional view of a first embodiment of a drive unit-impeller array. FIG. 3a shows a perspective view of a spacer for a drive unit-impeller array according to FIG. 2. Fig. 3b shows a front view of the spacer of Fig. 3a. FIG. 3c shows a side view of the spacer of FIG. 3a and FIG. 3b. FIG. 4a shows a perspective view of a first layer of a backplate having a post opening for a driving unit of an array according to FIG. 2. FIG. 4b shows a perspective view of a second layer of a backplate that does not have a post opening for the driving unit of the array according to FIG. 2. FIG. 4c shows a cross-sectional view of an assembled backplate including the first and second layers of FIG. 4a and FIG. 4b. FIGS. 5a to 5d illustrate a stage for manufacturing an intermediate product for the additional manufacturing of a post for a driving unit of an array according to FIG. 2. FIGS. 6a to 6c illustrate the welded portion of the intermediate product according to FIG. 5c. FIG. 7 shows a perspective view of a post separated from an intermediate product manufactured according to FIG. 5a to 6c. FIG. 8 shows a front view of the plan of the intermediate product of FIG. 6a having two welded seams and two cross-sections of the post to be cut from the intermediate product. FIG. 9 shows a front view of the end surface of a post having a welded portion. FIG. 10 shows a cross-sectional view of a second embodiment of a drive unit-impeller array. FIGS. 11a to 11c illustrate the steps of manufacturing an integral magnetic core for a driving unit according to FIG. 10. FIGS. 12a to 12c illustrate welds on an integral magnetic core manufactured according to FIGS. 11a to 11c. FIGS. 13a to 13j illustrate cross-sectional views through a post according to various embodiments. Specific details for implementing the invention
[0028] Referring to FIG. 1, a cross-sectional view of a blood pump (1) is illustrated. The blood pump (1) comprises a pump casing (2) having a blood flow inlet (21) and a blood flow outlet (22). The blood pump (1) is configured as an intravascular pump, also called a catheter pump, and is placed into a patient's blood vessel by a catheter (25). The blood flow inlet (21) is located at the end of a flexible cannula (23) which can be placed through a heart valve, such as an aortic valve, during use. The blood flow outlet (22) is located on a side surface of the pump casing (2) and can be placed within a heart blood vessel, such as an aorta. The blood pump (1) is electrically connected to an electrical line (26) extending through a catheter (25) to supply power to the blood pump (1) to drive the pump (1) by a drive unit (4), as described in more detail below.
[0029] When the blood pump (1) is intended for long-term use, that is, when the blood pump (1) is implanted in a patient for several weeks or even months, power is preferably supplied by a battery. This allows the patient to move because the patient is not connected to a base station by a cable. The battery can be carried by the patient and can supply electrical energy to the blood pump (1), for example, wirelessly.
[0030] Blood is transported along a passage (24) connecting a blood flow inlet (21) and a blood flow outlet (22) (blood flow is indicated by an arrow). An impeller (3) is provided to transport blood along the passage (24) and is mounted to be rotatable about a rotation axis (10) within a pump casing (2) by means of a first bearing (11) and a second bearing (12). The rotation axis (10) is preferably the longitudinal axis of the impeller (3). In this embodiment, both bearings (11, 12) are contact bearings. However, at least one of the bearings (11, 12) may be a non-contact bearing, such as a magnetic or hydrodynamic bearing. The first bearing (11) is a slewing bearing having a spherical bearing surface that allows rotational movement and some degree of slewing movement. A pin (15) forming one of the bearing surfaces is provided. A second bearing (12) is positioned on 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. A blade (31) is provided on the impeller (3) to carry blood when the impeller (3) rotates. The rotation of the impeller (3) is induced by a drive unit (4) magnetically coupled to a magnet (32) at one end of the impeller (3). The illustrated blood pump (1) is a mixed-type blood pump in which the main direction of flow is axial. It will be understood that the blood pump (1) may also be a purely axial blood pump depending on the arrangement of the impeller (3), particularly the blade (31).
[0031] The blood pump (1) includes an impeller (3) and a drive unit (4). The drive unit (4) includes a plurality of posts (40), such as six posts (40), of which only two are visible in the cross-sectional view of FIG. 1. The posts (40) are arranged parallel to the rotation axis (10), and more specifically, the longitudinal axis of each post (40) is parallel to the rotation axis (10). One end (420) of the post (40) is positioned adjacent to the impeller. A coil winding (44) is arranged around the post (40). The coil winding (44) is sequentially controlled by a control unit to generate a rotating magnetic field. A part of the control unit is a printed circuit board (6) connected to an electrical line (26). In this embodiment, the impeller has a magnet (32) formed from a plurality of piece magnets. The magnet (32) is positioned at the end of the impeller (3) facing the drive unit (4). The magnet (32) is arranged to interact with the rotating magnetic field to induce rotation of the impeller (3) around the rotation axis (10).
[0032] To close the magnetic flux path, a backplate (50) is positioned at the end of the post opposite the impeller side of the post (40). The post (40) acts as a magnetic core and is made of a suitable material, particularly steel or a suitable alloy, particularly a soft magnetic material such as cobalt steel. Likewise, the backplate (50) is made of a suitable soft magnetic material such as cobalt steel. The backplate (50) enhances the magnetic flux, which allows for a reduction in the overall diameter of the blood pump (1), which is important for the intravascular blood pump. For the same purpose, a yoke (37), that is, an additional impeller backplate, is provided on the impeller (3) at the side of the magnet (32) facing away from the drive unit (4). In this embodiment, the yoke (37) has a conical shape to guide blood flow along the impeller (3). The yoke (37) may also be made of cobalt steel. One or more wash-out channels extending toward the central bearing (11) may be formed in the yoke (37) or magnet (32).
[0033] FIG. 2 illustrates a cross-sectional view of a preferred first embodiment of a drive unit-impeller array for a blood pump according to FIG. 1. As can be seen in FIG. 2, the impeller-side end (420) of the post (40) does not extend radially over the winding (44). Rather, the cross-section of the post (40) is constant in the direction of the longitudinal axis (LA) of the post (40). Thus, the point where the posts (40) come close to each other, such as causing a partial magnetic short circuit resulting in reduced power of the electric motor of the blood pump, is avoided.
[0034] The drive unit according to FIG. 2 may include at least 2, at least 3, at least 4, at least 5, or preferably 6 posts (40). A larger number of posts (40), such as 9 or 12, may be possible. Due to the cross-sectional view, only 2 posts (40) are visible. The posts (40) and the backplate (50) form the magnetic core (400) of the drive unit (4), which may have a diameter of less than 10 mm.
[0035] The post (40) may be composed of a discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity, as illustrated. The discontinuous soft magnetic material comprises a plurality of sheets (85) made of a ferromagnetic material and laminated together. The direction of lamination is arranged in the direction of the longitudinal axis (LA) of the post (40) and is indicated by an arrow (DL). As illustrated, the post (40) is arranged parallel to the axis of rotation (10).
[0036] A spacer (7) is placed around the post (40). The spacer is made of a magnetically inert material and is intended to maintain a constant distance between the posts (40) at the impeller-side ends (420). The spacer (7) will be described in more detail in relation to FIGS. 3a through 3c. The impeller-side end (424) of the coil winding (44) extends to the spacer (7). A backplate (50) is provided at the other end of the post (40). According to the embodiment shown in FIG. 2, the backplate (50) has a recess for accommodating the post (40) inside. More specifically, the backplate comprises a first layer (51) having an opening (511) for the rear end (450) of the post (40). The backplate (50) will be described in more detail in relation to FIGS. 4a through 4c.
[0037] It is conceivable to realize an embodiment of a blood pump (1) having any combination of the following three features mentioned above: no radial extension of the impeller-side end (424) of a post over the impeller-side end of a winding (44), provision of a magnetically inert spacer (7) between the posts (40), and a backplate (50) having a recess for receiving the rear end (450) of a post (40).
[0038] FIGS. 3a through 3c illustrate a perspective view, a front view, and a side view of a spacer (7), respectively. The spacer (7) generally takes the form of a disc or wheel having a through hole (75) in the middle. The spacer (7) includes an opening (71) for each post. In the case of an embodiment having six posts (40), six openings (71) exist as illustrated. Between the openings (71), a separating spoke (72) is arranged. When the posts (40) are inserted into the openings (71), the separating spoke (72) maintains a constant distance between the posts (40). Additionally, the spacer (7) includes an outer rim (73) and an inner rim (74) that connect adjacent separating 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 posts (40). Titanium provides high mechanical strength to allow for the manufacture of a spacer (7) with a thin thickness. This is advantageous regarding the consumption of construction space.
[0039] FIG. 4a illustrates a perspective view of a first layer (51) of a backplate (50). The first layer (51) has the overall shape of a disk or wheel having a central hole (515). The first layer (51) includes an opening (511) into which the rear end (450) of a post (40) is arranged. The first layer (51) includes a separating spoke (512) arranged between the openings (511). One purpose of the separating spoke (512) is to keep the distance between the rear ends (450) of the posts (40) constant. Additionally, the first layer (51) includes an outer rim (513) and an inner rim (514) connecting the separating spokes (512) at the outer radial end and the inner radial end, respectively, of the opening (511). The first layer (51) may be made of a discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity. This may consist of several ferromagnetic sheets (85), specifically three sheets, as shown in FIG. 4a. The sheets (85) are laminated together with an electrically non-conductive material to form a discontinuous soft magnetic material. The direction (DL) of the lamination is generally parallel to the sheets (85), and the direction of the main extension of the sheets defines the plane of the lamination. 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). The purpose of this may be to facilitate the assembly of the first layer (51) and the second layer (52), for example, centering the first layer (51) and the second layer (52).
[0040] In FIG. 4b, a perspective view of the second layer (52) of the backplate (50) is shown. The second layer (52) has a disc shape having a hole (525) in the middle that corresponds substantially to the hole (515) of the first layer (51). The second layer (52) does not have any opening for the rear end of the post (40). Instead, the second layer (52) has a contact plane (526) facing the rear end (450) of the post (40). The rear ends (450) of the posts are in contact with the contact plane (526) of the second layer (52) of the backplate (50) to transmit magnetic flux between the rear end (450) of the post (40) and the backplate (50) in the assembled state of the drive unit. When all rear ends (450) of the posts (40) come into contact with the contact plane (526), magnetic flux can be exchanged between the posts (40), and a magnetic zero can be formed in the second layer (52). To make this possible, the second layer (52) is made of a soft magnetic material. The soft magnetic material may be a discontinuous soft magnetic material with respect to electrical conductivity and may include sheets (85) laminated together similarly to the structure described above with respect to the first layer (51). As one embodiment, three sheets (85) may constitute the second layer (52) as shown in FIG. 4b. In the second layer (52), the direction (D) of the lamination is perpendicular to the axis of rotation (10). The sheets (85) are ferromagnetic and electrically conductive, while the intermediate layer (not explicitly shown) between the sheets (85) is non-ferromagnetic and electrically non-conductive. This type of discontinuous soft magnetic material reduces eddy currents that would otherwise be generated in greater quantities by changes in magnetic flux. The hole (525) in the center of the second layer (52) may be intended to facilitate the assembly of the first layer (51) and the second layer (52), for example, centering the first and second layers (51, 52).
[0041] FIG. 4c illustrates a cross-section of a backplate (50). It consists of a first layer (51) and a second layer (52) that are joined together at the main surface having the largest extension. The joining between the first layer (51) and the second layer (52) of the backplate (50) can be established in the same way as between the sheets (85) of the first and second layers (51, 52). Through holes (515, 525) of the first layer (51) and the second layer (52) are aligned with each other to center the first and second layers (51, 52). By laminating the first and second layers (51, 52), the opening (511) is closed at one end by the second layer (52) so that a recess (501) is formed to accommodate the rear end (450) of the post (40). A contact plane (526) is formed on the ground of the recess (501). When the post (40) is inserted into the recess (501), its rear end (450) comes into contact with the contact plane (526). Additionally, the position of the post (40) is secured by the outer and inner rims (513, 514) that surround each of the posts (40) together, as well as by the separating spoke (512). In this way, a magnetic connection is established between the rear end surface (45) of the post (40) and the second layer (52) at the contact plane (526), and additionally, a second magnetic connection is established between the post (40) and the peripheral portion of the first layer (51) described above. However, the main part of the magnetic flux is transmitted through the contact plane (526). Preferably, the surface of the rear end (450) of the post (40) has a predefined flatness, and the contact plane (526) also has 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 preferably be kept to a specific size of less than 10 μm. This improves the transmission 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 present invention, the transmission of magnetic flux through the surface (45) and the backplate (50) is independent of the method of fixing the post (40) to the backplate (50).
[0042] FIGS. 5a to 5d illustrate the preparation steps for manufacturing the post (40). FIG. 5a illustrates a perspective view of a plate (8) of a discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity, which is also referred to as the workpiece below.
[0043] In FIG. 5a, the plate (8) is shown with a width (W) for cutting the workpiece rod (81) from the plate (8). The width (W) of the workpiece rod (81) is equal to the length of the post (40) to be produced from the workpiece rod (81). An enlarged view of the portion marked by the rectangle R in FIG. 5a is shown in FIG. 5b. Here, laminated sheets (85) of discontinuous soft magnetic material are visible. The direction (DL) of the lamination follows the main plane of the plate (8) and thus forms a plane of lamination.
[0044] FIG. 5c illustrates a workpiece rod (81) cut from a plate (8) as individual pieces of discontinuous material. An enlarged view of the portion marked by the rectangle R in FIG. 5c is shown in FIG. 5d. Sheets (85) of the workpiece rod (81) are visible in this enlarged view.
[0045] FIG. 6a illustrates the workpiece rod (81) of FIG. 5c and FIG. 5d, which forms the basis of the welding step in preparation for cutting the post (40) from the rod (81). On the side plane of the rod (81) pointing to the left in FIG. 6a, a plurality of cross-sections (84) of the post (40) to be manufactured from the rod (81) are shown. The post (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 post (40), the side surfaces (811, 812) of the rod (81) become the end surfaces of the impeller-side end (420) and the rear end (450) of the post (40).
[0046] FIG. 6b illustrates the next preparation step before cutting the post (40). Two weld seams (82 and 83) are welded to the face (811) of the rod (81) at a distance from each other across each cross section (84) of the post (40) to be cut. The weld seams (82 and 83) are perpendicular to the direction (DL) of the lamination of the sheet (85). In this way, sheets of discontinuous material are connected to each other. Instead of two weld seams, a single weld seam may be provided. Additionally, a similar weld seam may be provided on the opposite side face (812) of the rod (81). The sheets (85) have a better mechanical connection to each other due to the weld seams (82, 83), and are also electrically connected. The latter has the advantage that current can flow from any location of the discontinuous soft magnetic material to be the post (40) to each location of the electrical connection of the rod (81) that may be required for electrical discharge machining, for example. In this way, electrical discharge machining is greatly facilitated. Furthermore, higher process reliability is achieved because the cutout post (40) cannot be detached by peeling. Preferably, laser welding is applied. It may be advantageous to apply welding power to the same weld two or more times. The portion of the rod (81) indicated by the rectangular R is shown in enlargement in FIG. 6c.
[0047] Accordingly, FIG. 6c illustrates a plurality of cross-sections (84) of a post (40) to be cut from a rod (81). The cross-section (84) has a substantially triangular shape. As illustrated, the corners may be rounded. The convex side (842) of the triangle illustrated on the left side of the cross-section (84) in FIG. 6c has a convex shape. This type of cross-section (84) is advantageous for making full use of the available configuration space inside the cylindrical pump housing (2). The bisector of the corner (841) of the opposite cross-section (84) to the convex side (842) of the cross-section (84) is aligned with the direction (DL) of the lamination. In this way, the sheets (85) are symmetrically connected through the cross-section (84).
[0048] FIG. 7 illustrates a post (40) cut from a rod (81). As can be seen on the surface (45) at the rear end (450) of the rod (81), weld seams (82, 83) are still present on this surface. The post (40) has a constant cross-section (84) along its entire length. The weld seams (82 and 83) are deburred after the post (40) is cut out.
[0049] FIG. 8 illustrates a different arrangement of two cross-sections (84) on one side surface (811) of a workpiece rod (81). In contrast to the workpiece rod (81) illustrated in FIG. 6a through 6c, the side surface (811) of the workpiece rod (81) in FIG. 8 has a size that allows two cross-sections (84) to be placed next to each other in a direction perpendicular to the lamination direction (DL). The cross-sections (84) are oriented with respect to the lamination direction (DL) such that the bisector (B) of each corner of the opposite cross-section (84) on each convex side (842) is aligned with the lamination direction (DL). By arranging the cross-sections (84) along the rod (81) in this manner, material can be saved. Less waste is generated. Depending on the thickness of the rod (81) and the required cross-sectional dimensions of the post (40), it is conceivable to laminate more cross-sections (84) of the post (40) in a direction perpendicular to the lamination direction (DL). Welding seams (82, 83) extend across each cross-section (84). Welding seams (82, 83) also extend across the entire side surface (811) of the rod (81) in a direction perpendicular to the lamination direction (DL). In this way, all sheets (85) of the discontinuous soft magnetic material of the rod (81) are connected to each other.
[0050] FIG. 9 illustrates an embodiment of a post (40) cut out from a welding rod (81), namely a front view of one of the end surfaces of the post (40). As shown in FIG. 9, a single weld seam (86) of considerable width, capable of covering more than about one-third of the height of the triangular section (84), runs along the convex side (842) of the section (84). The weld seam (86) runs perpendicular to the direction of lamination (DL) to connect all the sheets. Additionally, the bisector (B) of the opposite corner (841) on the convex side (842) is aligned with the direction of lamination (DL).
[0051] FIG. 10 illustrates a second embodiment of a drive unit-impeller array for a blood pump (1) according to FIG. 1. Similar to the first embodiment illustrated in FIG. 2, the impeller-side end (420) of the post (40) does not extend radially over the winding (44). Rather, the cross-section of the post (40) is constant in the direction of the longitudinal axis (LA) of the post (40). Thus, the point where the posts (40) come close to each other, such as causing a partial magnetic short circuit resulting in reduced power of the electric motor of the blood pump, is avoided.
[0052] The drive unit according to FIG. 10 may include at least 2, at least 3, at least 4, at least 5, or preferably 6 posts (40). A larger number of posts (40), such as 8, 10, or 12, may be possible. Due to the cross-sectional view, only 2 posts (40) are visible. The posts (40) and the backplate (50) form the magnetic core (400) of the drive unit (4), which may have a diameter of less than 10 mm.
[0053] This embodiment differs from the first embodiment shown in FIG. 2 by a different structure of the magnetic core. Here, the magnetic core (400) comprises the magnetic components of the drive unit (4), which are the post (40) and the backplate (50), as a single unit or monoblock. The monoblock is composed of a discontinuous soft magnetic material. The discontinuous soft magnetic material is discontinuous with respect to electrical conductivity. As illustrated, this comprises a plurality of sheets (85) of ferromagnetic material laminated together to form a monoblock (9), as illustrated in FIG. 11c. The direction (DL) of the lamination is parallel to the axis of rotation (10).
[0054] The coil winding (44) extends to the impeller-side end (420) of the post (40). This has the advantage that magnetic force can be generated along the entire post (40). The magnetic core (400) includes a protrusion (401) at the rear end (450) of the post (40) that protrudes radially relative to the post (40). This protrusion (401) may be a stop for the coil winding (44) toward the backplate (50). Because the integral magnetic core (400) has high rigidity between the backplate (50) and the post (40), spacers between the posts (40) at the impeller-side end (420) of the post can be omitted. The integral magnetic core (400) provides the advantage that optimal magnetic connection between the post (40) and the backplate (50) can be achieved. The magnetic core (400) may have a diameter of less than 10 mm.
[0055] FIGS. 11a through 11c illustrate the steps of manufacturing a magnetic core (400) for a drive unit (4) of a drive unit-impeller array as illustrated in FIG. 10. FIG. 11a is a perspective view of a cubic monoblock (9) forming a workpiece for manufacturing the magnetic core (400). The monoblock (9) is composed of a discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity. It comprises a sheet (85) oriented in the direction (DL) of lamination extending along the main plane of the sheet (85). The sheet (85) is bonded to each neighboring sheet by a bonding layer of electrically non-conductive material not explicitly illustrated in FIGS. 11a through 11c.
[0056] FIG. 11b illustrates a semi-manufactured magnetic core (400) that has been turned, for example, from a cubic monoblock (9) into a substantially cylindrical body (94). In this machining step, a protrusion (401) is manufactured. A section (404) of reduced diameter of the body (94) forming the peripheral surface of the post (40) of the magnetic core (400) is manufactured with a diameter corresponding to the outer radius of the outermost convex side surface (842) of the post (40).
[0057] Next, the body (94) can be further manufactured to produce a magnetic core (400) as illustrated in FIG. 11c. In this production step, electrical discharge machining may be used. In particular, electrical discharge machining by wire cutting may be applied to create a slot (49) that separates the posts (40) from one another. Inside the slot, space is provided for a coil winding (44). At the ground of the slot (49), an intermediate region (59) of the integral backplate (50) extends between the rear ends of the posts (40). The intermediate region is integrated with the posts (40) and the backplate (50). Thus, the entire magnetic core is formed by the monoblock (9).
[0058] The lamination direction (DL) in the magnetic core (400) is made to be parallel to the axis of rotation (10). It is acceptable that the lamination direction (DL) of the base plate (50) is not parallel to the magnetic flow between the posts (40) of the base plate (50). It is also possible to manufacture the magnetic core (400) from a coiled soft magnetic sheet material separated by an electrically non-conductive layer. Then, the lamination direction (DL) of the base plate (50) is always in the circumferential direction, which is advantageous for avoiding eddy currents of the magnetic flux of the base plate (50).
[0059] FIGS. 12a through 12c illustrate how one or more welds may be provided on the surface of an integral magnetic core manufactured according to FIGS. 11a through 11c. Accordingly, in the illustrated embodiment, three weld seams (82, 83) are provided on one side surface of a cubic monoblock (9). The weld seams (82, 83) are welded spaced apart from each other across the cross-section of the body (94) to be cut from the monoblock (9). The weld seams (82, 83) are extended perpendicular to the direction (DL) of the lamination of the sheet (85). In this way, sheets of discontinuous soft magnetic material are connected to each other. Instead of three weld seams, more weld seams or a single wide weld may be provided. Additionally, similar weld seams may be provided on the opposite side of the monoblock (9) (not shown). Alternatively, or in addition to welding on the opposite side surface, one or more weld seams may be provided on the side surface of the monoblock (9) at the level of the backplate (50) to completely or at least partially surround the backplate (50). The sheets (85) have better mechanical connections with each other due to the weld seams (82, 83) and are also electrically connected. The latter has the advantage that current can flow from any location of the discontinuous soft magnetic material to, for example, each location of the electrical connection of the body (94) that may be required for electrical discharge machining. In this way, electrical discharge machining is greatly facilitated. In addition, higher process reliability is achieved because the backplate-post unit cut from the body (94) cannot be detached by peeling. Preferably, laser welding is applied. It may be advantageous to apply welding power to the same weld two or more times.
[0060] FIGS. 13a through 13j illustrate various embodiments of a post shown in cross-section. FIGS. 13a through 13d illustrate an embodiment in which the post is slotted, i.e., formed of a plurality of sheets (171) insulated from one another by an insulating layer (172). The insulating layer (172) may include an adhesive, a lacquer, or a baking enamel, etc. FIGS. 13a and 13b illustrate an embodiment in which the thickness of the sheets (171) is uniform. The thickness may be within the range of 25 μm to 450 μm. The sheet (171) shown in FIG. 13a has a thicker thickness than the sheet (171) shown in FIG. 13b. The sheets in FIG. 13c have varying thicknesses, with the central sheet having the greatest thickness and the outermost sheet having the smallest thickness. This may be advantageous because eddy currents in the lateral regions of the post are more significant and can be reduced by the thinner sheets. Eddy currents are less important in the central region, and a relatively thick central sheet can help improve magnetic flux. The orientation of the sheet (171) may vary, as exemplarily illustrated in FIG. 13d, insofar as the soft magnetic material in the illustrated cross-section is discontinuous or interrupted in the cross-section across the direction of the magnetic flux.
[0061] FIGS. 13e and FIGS. 13f illustrate an embodiment in which a post (141) is formed by a bundle of wires (181) that are insulated from one another by an insulating material (182). The insulating material (182) may exist as a coating on each wire (181) or as a matrix in which the wires (181) are embedded. In the embodiment of FIG. 13e, all wires have the same diameter, whereas in the embodiment of FIG. 13f, the center wire has the largest diameter and the outer wires have smaller diameters, which is similar to the embodiment illustrated in FIG. 13c, which has sheets of varying thicknesses. As illustrated in FIG. 13g, wires (181) of different diameters may be mixed, which can increase the total cross-sectional area of the soft magnetic material compared to the embodiment in which all wires have the same diameter. Alternatively, to further minimize the insulating layer (184) between the wires (183), the wire (183) may have a polygonal cross-sectional area such as a rectangle, a square, etc.
[0062] Alternatively, the discontinuous cross-section of the post (141) may be created by metal particles (185) embedded in a polymer matrix (186) as shown in FIG. 13i, or by steel wool or other porous structures impregnated with an insulating matrix. The porosity of the soft magnetic material, and thus the discontinuous structure, may also be created by a sintering process or a high-pressure molding process, in which the insulating matrix may be omitted because the insulating layer is automatically formed by the oxidation of the soft magnetic material by exposure to air. Alternatively, the post (141) may be formed from a wound sheet (187) of soft magnetic material in which a layer of the wound sheet (187) is separated by an insulating layer (188) as shown in FIG. 13j. This also provides a discontinuous cross-section in the sense of the present invention for reducing eddy currents in the post (141) or the post (40).
Claims
Claim 1 In an intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, the pump casing (2) having a blood flow inlet (21) and a blood flow outlet (22); an impeller (3) arranged within the pump casing (2) so as to be rotatable about a rotation axis (10) - the impeller (3) having a blade (31) that is sized and shaped to transport blood from the blood flow inlet (21) to the blood flow outlet (22) - a driving unit (4) for rotating the impeller (3) - the driving unit (4) includes a plurality of posts (40) arranged about the rotation axis (10), each of the posts (40) having an impeller-side end (420) facing a longitudinal axis (LA) and the impeller (3) - and a coil disposed around each of the posts (40) and having an impeller-side end (424) facing the impeller (3). A coil winding (44) - said coil winding (44) is controllable to generate a rotating magnetic field -, wherein the impeller (3) includes a magnetic structure (32) arranged to interact with the rotating magnetic field to induce rotation of the impeller (3), and at least one of the posts (40) does not extend in a state where the impeller-side end (420) of said at least one of the posts is radially positioned over the impeller-side end (424) of said coil winding (44) arranged around said at least one of the posts (40), and said radially refers to a direction crossing the longitudinal axis (LA) of said at least one of the posts (40), and a spacer (7) arranged at the impeller-side ends (420) of said post (40) and configured to maintain a constant distance between the impeller-side ends (420) of said at least two of the posts (40). Including, an intravascular blood pump (1). Claim 2 In claim 1, the impeller-side end (420) of at least one of the posts (40) is flat and oriented perpendicularly to the rotation axis (10), an intravascular blood pump (1). Claim 3 In claim 1, the spacer (7) has the shape of a disc having an opening (71) for accommodating at least two posts among the posts (40), an intravascular blood pump (1). Claim 4 In paragraph 3, each of the openings (71) has a shape corresponding to the cross-section (84) of each of the at least two posts among the posts (40), an intravascular blood pump (1). Claim 5 In any one of claims 1, 3, or 4, the spacer (7) has a thickness of 0.05 to 0.3 mm, and is an intravascular blood pump (1). Claim 6 In any one of claims 1, 3, or 4, the spacer (7) is made of a non-ferromagnetic material, and the intravascular blood pump (1) is. Claim 7 In paragraph 6, the above spacer (7) is an intravascular blood pump (1) made of titanium. Claim 8 In any one of claims 1, 3, or 4, the coil winding (44) is an intravascular blood pump (1) in which the impeller-side end of the coil winding extends to the spacer (7). Claim 9 In any one of claims 1 to 4, the at least one post among the posts comprises a discontinuous soft magnetic material that is discontinuous with respect to electrical conductivity in a cross-section across the longitudinal axis (LA) of each post (40), or is composed of the discontinuous soft magnetic material, an intravascular blood pump (1). Claim 10 In any one of claims 1 to 4, the back plate (50) magnetically connecting the end of the post (40) located opposite the impeller-side end (420) comprises a soft magnetic material that is discontinuous with respect to electrical conductivity in a cross section parallel to the rotation axis (10), in a blood pump (1). Claim 11 In any one of claims 1 to 4, the intravascular blood pump (1) wherein at least one of the posts (40) has a triangular cross-section that crosses the longitudinal axis (LA) of each of the posts (40). Claim 12 In claim 11, one side of the at least one post (40) having the above-mentioned triangular cross-section is directed away from the rotation axis (10) and is curved around the rotation axis (10), forming an intravascular blood pump (1). Claim 13 In any one of claims 1 to 4, the radial shape relates to a direction perpendicular to the longitudinal axis (LA) of at least one post among the posts (40), an intravascular blood pump (1). Claim 14 In claim 5, the spacer (7) is an intravascular blood pump (1) having a thickness of 0.066 to 0.2 mm. Claim 15 In claim 5, the spacer (7) is an intravascular blood pump (1) having a thickness of 0.1 mm. Claim 16 delete Claim 17 delete
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