Method for manufacturing a bearing mechanism for an implantable blood pump, bearing mechanism and implantable blood pump

Abstract

The present invention relates to a method for manufacturing a bearing mechanism for an implantable blood pump (2), a bearing mechanism, and an implantable blood pump (2). In the proposed method, a rotor (8) having one or more drive magnets is provided. The rotor (8) has a conveying member (9). A stator (13) having a stator winding is also provided. In addition, the rotor (8) is arranged in a flow channel (10) formed by the inner wall of the stator (13). Then the rotor is driven to rotate. During the driving of the rotor to rotate, the offset of the rotor (8) is determined. In a further step, the offset of the rotor (8) is corrected by non-rotationally symmetrically applying, removing, magnetizing, and / or demagnetizing magnetically effective material on the stator (13) and / or the rotor (8).

Description

Technical Field

[0001] This application is in the field of medical technology, especially in the field of implantable blood pumps for assisting heart function. This application relates to a method for manufacturing a bearing mechanism for an implantable blood pump, the bearing mechanism, and an implantable blood pump. Background Art

[0002] Blood pumps have been disclosed in the prior art. The blood pumps can be used when it is necessary to assist or replace the heart function of a patient. A common system used at this time is a so-called VAD (ventricular assist device). Such a heart pump can be designed, for example, as a so-called LVAD (left ventricular assist device), RVAD (right ventricular assist device), or BiVAD (biventricular assist device). In addition to the blood pump implanted in the patient during operation, the system usually also includes, for example, a control device arranged outside the patient's body and connected to the blood pump through a pipeline (power transmission system). The blood pump generally includes a motor having a stator and a rotor with blades, which is arranged in the flow channel of the blood pump. The motor of the blood pump can be driven by the energy provided by the control device because, for example, a current is generated in the stator winding, and the rotor together with the blades rotates through the current to pump the patient's blood.

[0003] Especially in a blood pump with a magnetic mount having a small gap width between the rotor blades and the inner wall of the flow channel (which is especially for axial and semi-axial flow geometries), a reliable blood pump function may require an accurately controllable position of the rotor within the blood pump flow channel. For example, the publication EP 3300749A1 describes a blood pump having a rotor that is radially passively magnetically mounted. If precise adjustment of the rotor position is required, the manufacture of the magnetic bearings of the blood pump may be relatively expensive because the permanent magnets used as raw materials for the magnetic bearings generally may have non-negligible tolerances in their magnetic properties. In order to produce a blood pump with an accurately adjusted rotor position, for example, multiple permanent magnets can be installed in the blood pump, their magnetic properties can be tested, and they can be replaced continuously until the desired magnetic properties are obtained. However, this method is costly and will increase the number of defective products. Summary of the Invention

[0004] The task of this application is to propose an improved method for manufacturing a bearing mechanism for an implantable blood pump. In particular, the proposed method should be relatively fast and inexpensive and allow the manufacture of a blood pump in which the magnetic characteristics and the rotor position are accurately adjusted. In addition, the task of this application is to propose a correspondingly advantageous bearing mechanism and a correspondingly advantageous implantable blood pump.

[0005] In the proposed method of manufacturing a bearing mechanism for an implantable blood pump, a rotor having one or more drive magnets is provided. The rotor has a delivery member. A stator having stator windings is also provided. Further, the rotor is disposed in a flow channel formed by the inner wall of the stator. When the blood pump is implanted and operating, blood is delivered through the flow channel. Herein, the rotor is driven to rotate especially by generating a current in the stator windings. During the manufacturing process, the rotor is driven to rotate and the rotor offset is determined. In a further step, the rotor offset is corrected by non-rotationally symmetrically applying, removing, magnetizing, and / or demagnetizing magnetically effective material on the stator and / or the rotor. In some embodiments, the bearing mechanism can be part of an electric motor of the blood pump, which electric motor further includes the stator and the rotor.

[0006] By the proposed method, a bearing mechanism for a blood pump can be manufactured that allows for precise positioning of the rotor during operation. Thereby, these bearing mechanisms operate very smoothly and are thus durable and highly energy-efficient. Further, if the rotor can be precisely positioned in its neutral position, the pump can operate over a wider operating range. By the method step of determining the rotor offset, a possible magnetic imbalance caused by the stator and rotor magnets used can be determined and subsequently corrected in a targeted manner. The determination of the rotor offset refers to the determination of the position or distance or angle of the rotor relative to a reference point or reference axis. Compared to manufacturing methods that test and select a large number of different rotor or stator magnets, the method steps described herein enable the manufacture of blood pumps with the desired magnetic properties with fewer rejects and thus save materials and costs. Another advantage is that rotors and stators magnetically corrected according to the proposed method generally do not require any other measures for correcting magnetic properties in the final assembly, so the following steps can be performed relatively quickly and easily in the manufacture of the electric motor or blood pump. The present application can also relate to a method for manufacturing a blood pump, the method including the method steps for manufacturing the bearing mechanism.

[0007] Since this method is a manufacturing method rather than an operating method, the offset correction can be completed before the blood pump operation, especially once and / or permanently. The application, removal, magnetization, and / or demagnetization of the magnetically effective material on the stator and / or rotor are usually long-term or permanently maintained. In particular, the magnetically effective material can be permanently magnetized and / or demagnetized during the correction according to the proposed manufacturing method. Therefore, in typical embodiments, the magnetic material is not a current-carrying conductor, especially not a current-carrying coil. In some embodiments, no further adjustment, especially permanent adjustment, is required during the operation of the blood pump. Since this method is a manufacturing method, the method steps are generally not carried out in the human body or animal body. After correction, it is generally stipulated to deliver a blood pump containing a corrected bearing mechanism. Additionally or alternatively, especially before delivery, it can be stipulated that one or the blood pumps containing a corrected bearing mechanism are aseptically packaged. Preferably, it is stipulated that the bearing mechanism constitutes a passive magnetic bearing. In this way, a simple structure of the bearing mechanism is obtained. Additionally, the above-described and the following manufacturing methods are especially suitable for the correction in passive magnetic bearings because they have permanent magnetic properties that can be corrected particularly effectively during manufacturing. In a preferred embodiment, the magnetically effective material is applied, removed, magnetized, or demagnetized to, from, or on the rotor during the correction, which will be described in more detail below.

[0008] In a preferred embodiment, it is stipulated that the bearing mechanism includes a magnetic radial bearing having at least one rotor bearing magnet and at least one stator bearing magnet. The offset of the rotor can be a radial offset. It can also be stipulated that the radial offset of the rotor is determined when driving the rotor to rotate. Then, the radial offset can be corrected as described above or below. In this case, the radial offset, for example, relative to the center point of the flow channel or the cylindrical symmetry axis, is usually reduced. In this way, precise control of the gap width in the flow channel between the stator and the rotor can be achieved.

[0009] The rotational characteristics of the rotor depend on the motor operating speed. At this time, the rotor can rotate around its magnetic center of gravity axis at a subcritical (low) speed (below the resonance frequency) and perform a swinging motion, while rotating around the inertial axis at a supercritical (high) speed (above the resonance frequency).

[0010] In some embodiments, the determination of the radial offset is performed when driving the rotor to rotate at a rotational speed at which the rotor basically rotates around its inertial axis. Then, the rotor radial offset can be reduced by non-rotationally symmetrically applying, removing, magnetizing, and / or demagnetizing the magnetically effective material on the stator.

[0011] The reference point for determining the offset can be, for example, the central symmetry axis or the cylindrical symmetry axis of the flow channel. After correction, the geometric center of gravity axis of the rotor can coincide with the cylindrical symmetry axis of the flow channel, for example, so that the rotor is basically centered or rotates in the flow channel in the working area.

[0012] In this case, the determination of the offset is carried out at a relatively high rotational speed, at which the rotor rotates stably about its axis of inertia. In this case, the position of the rotor is usually stable, so that the offset is independent of time. Usually, the position of the rotor is mainly influenced by the magnetic field of the stator bearing magnets. Therefore, an exact adjustment of the rotor position can be obtained by correcting the stator. Usually, when determining the rotor offset, the rotor operates in a supercritical state. The resonance speed (above which the rotor operates supercritically) is usually geometry-related and can be at least 2000 rpm, for example, especially greater than 3000 rpm in the case of a radial pump system and especially likely to be greater than 6000 rpm in the case of an axial pump system.

[0013] Additionally or alternatively, it can be provided that the determination of the radial offset is carried out when driving the rotor to rotate at a speed at which the rotor rotates substantially about its magnetic center of gravity axis. Then, the rotor offset can be corrected by non-rotationally symmetric application, removal, magnetization, and / or demagnetization of the magnetically effective material on the rotor.

[0014] In this case, the determination of the rotor offset is usually carried out at a low rotational speed, at which the rotor rotates about its magnetic center of gravity and the rotor offset is time-dependent, so that the rotor performs a certain wobbling or oscillating motion. In this case, by correcting the magnetic imbalance on the rotor, control of the rotor position can be obtained particularly effectively. Thus, the determination of the offset is usually carried out in subcritical operation at a rotational speed of at most 500 revolutions per minute. The correction of the magnetic imbalance on the rotor is usually carried out in such a way that the rotor then rotates stably with a constant radial offset over time.

[0015] In some embodiments, in order to precisely adjust the magnetic properties of the bearing mechanism or the electric motor, the correction is first carried out under subcritical conditions and then under supercritical conditions.

[0016] For example, in some embodiments, it can be provided that when driving the rotor to rotate, a liquid is arranged in the flow channel between the stator and the rotor. Therefore, the measurement is carried out approximately under real operating conditions (at which the liquid is arranged in the flow channel and is conveyed through the flow channel).

[0017] The rotor offset when driving the rotor to rotate can be determined particularly simply, for example, by means of a microscope and / or a distance measuring sensor and / or an acceleration sensor.

[0018] In a typical embodiment, the rotor offset is corrected by applying a magnetizable material and / or a magnetic material. The material can in particular be a permanent magnetic material or a soft magnetic material such as NdFeB or an iron sheet or a soft magnetic alloy. Thereby, the correction can be carried out relatively simply, predictably, and particularly effectively. This applies in particular to the case of correcting the stator, since in this case no mechanical imbalance that may exist or be generated needs to be considered.

[0019] For example, it can be stipulated that the correction of the rotor offset is carried out by non-rotationally symmetrically applying or removing magnetically effective material on the rotor. In this case, it can also be advantageous to remove from the rotor or apply to the rotor magnetically ineffective material such as non-magnetic stainless steel or brass to correct the mechanical imbalance of the rotor.

[0020] The mechanical imbalance may be caused, for example, by the magnetic correction of the rotor offset. For example, magnetically ineffective material can be removed from the rotor or applied to the rotor in such a way that the influence of the magnetic correction on the inertial axis of the rotor is compensated. In this way, it is possible to avoid inadvertently generating a mechanical imbalance along with the magnetic correction, which helps to improve the running smoothness when correcting the rotor.

[0021] If magnetically ineffective material is applied to the rotor to correct the mechanical imbalance of the rotor, it can be applied, for example, on the opposite side of the rotor with respect to the inertial axis of the rotor and with respect to the magnetically effective material applied non-rotationally symmetrically to the rotor. The magnetically ineffective material can, for example, have substantially the same or a similar density as the magnetically effective material, whereby the correction of the mechanical imbalance becomes particularly simple. For example, the magnetically effective material can substantially contain iron, while the magnetically ineffective material can substantially contain non-magnetic, in particular antiferromagnetic, stainless steel. In other embodiments, the magnetically effective material and the magnetically ineffective material can be, for example, differently filled polymers. For example, the different densities of the magnetically effective compensation material and the magnetically ineffective compensation material can be compensated by deliberately different profiles of the materials. By applying the magnetically ineffective material, the geometric symmetry axis of the rotor generally coincides with its inertial axis. The removal of the magnetically effective material and / or the magnetically ineffective material can be carried out in an exact manner, for example, by grinding.

[0022] In some embodiments, the correction of the rotor offset is carried out by non-rotationally symmetric magnetization or demagnetization of the magnetically effective material of the rotor. In this case, generally no local mass change will occur here. In this way, it is achieved that no mechanical imbalance is inadvertently generated by the magnetic correction of the rotor. The magnetization or demagnetization can be carried out, for example, in a thermal manner and perhaps in the presence of an applied magnetic field. For example, the magnetically effective material can be locally heated with a laser or a soldering iron to a temperature above the Curie temperature of the material.

[0023] The present application also relates to a correspondingly advantageous bearing mechanism for an implantable blood pump. The bearing mechanism can be manufactured by the methods described above or below. The present application also relates to a correspondingly advantageous implantable blood pump. The blood pump can include a motor having a rotor and a stator. The blood pump can also include a bearing mechanism, the passive magnetic radial bearing of which includes the rotor bearing magnets and, if necessary, additional rotor bearing magnets, as well as the stator bearing magnets and, if necessary, additional stator bearing magnets. The blood pump can also include magnetically effective material applied to the rotor and / or stator in a non-radially symmetric manner to define and / or correct the radial offset of the rotor. Generally, the radial offset of the rotor is defined or corrected in such a way that the geometric centroid axis of the rotor coincides with the cylindrical symmetry axis of the flow channel, or the pump is preloaded in a certain direction according to the force relationship during operation. The magnetically effective material can be, for example, soft magnetic or permanent magnetic. In some embodiments, the magnetically effective material is, for example, a soft magnetic strip, which is particularly applied to a part of the stator from the outside. In other embodiments, the magnetically effective material can be a magnetically active rod, particularly a semi-circular rod, such as an iron rod, which is arranged on the rotor, particularly in an inner groove of the rotor. For the strip or rod, it is possible to particularly reliably predict which length and thickness cause how strong an offset magnetic correction.

[0024] The implantable blood pump can also include a magnetic axial bearing, particularly a passive magnetic axial bearing. Through this bearing, the rotor can be magnetically preloaded axially, for example, by pressing the rotor against the bearing surface of a spherical or non-spherical spherical crown bearing or conical bearing.

[0025] Generally, the offset of the rotor is corrected in such a way that the clearance width between the rotor, and in particular the blades, and the inner wall of the stator, which particularly completely surrounds the rotor, is at least 20 μm and / or at most 500 μm.

[0026] It is common in the proposed method that a specific composition of the magnetically effective material of the rotor or stator is maintained during the correction. In particular, it can be specified that during the correction, at least 50% by volume, particularly at least 80% by volume, of the magnetically effective material of the stator or rotor, particularly the stator bearing magnet or rotor bearing magnet having invariant magnetism, is maintained. Thus, for example, the stator bearing magnet or rotor bearing magnet is generally not completely replaced. Description of the Drawings

[0027] The features described above or below regarding the manufacturing method can be correspondingly used for the bearing mechanism or the blood pump, and vice versa.

[0028] Embodiments are described below in conjunction with the drawings, where:

[0029] Figure 1 A schematic diagram of a blood pump implanted in a patient is shown,

[0030] Figure 2 A schematic view of an electric motor of a blood pump is shown.

[0031] Figures 3(a) to 3(c) A schematic view for illustrating various different method steps in the manufacture of a blood pump is shown.

[0032] Figure 4 A view for illustrating the correction of the rotor position of an electric motor is shown. Detailed Description

[0033] Figure 1 The body 1 of a patient is schematically shown, in which a blood pump 2 for assisting the function of the heart 3 is implanted. The blood pump 2 has an electric motor which is generally designed to have a rotatable conveying member, and this electric motor is accommodated in the pump body 4 of the blood pump 2. The pump body 4 is connected to a control device 5, which can also be implanted, as schematically shown. In some embodiments, the control device 5 can also be wholly or partly accommodated in the implanted pump body 4. In other embodiments, the control device 5 is provided outside the body. The pump body 4 further includes an inlet passage 6 which is connected to the inlet cannula of the pump body 4, through which blood can be drawn from the chamber of the heart 3 and sent through the cannula 7 into the blood vessel 8. The control device 5 is provided for controlling the motor of the blood pump 2 to pump blood.

[0034] Figure 2 A schematic view of the electric motor 6 of the blood pump 2 is shown. In this figure and in the following figures, repeated features carry the same reference numerals. The electric motor 6 is accommodated in the pump body 4 and includes a rotor 8 and a stator 13. The rotor 8 has a rotatable conveying member 9 or forms the conveying member 9. A flow passage 10 is defined by the inner wall 16 of the stator 13 which is substantially cylindrical in the region shown, through which blood is conveyed during the operation of the blood pump 2. The rotor 8 or the conveying member 9 includes vanes 11, 11', which are used for conveying blood, for example, in a direction opposite to the direction of the arrow with reference numeral 12 and towards Figure 2 the shown cannula 7. In order to effect the rotation of the rotor 8 for conveying blood, a current which is electronically controlled by the control device 5 is generated in the winding 14 of the stator 13. The magnetic field generated by the current in the winding 14 causes the drive magnet 15 of the rotor 8 to rotate, and this drive magnet can be designed, for example, as a permanent magnet and is generally rigidly connected to the remainder of the rotor 8 and in particular to the vanes 11, 11'.

[0035] The electric motor 6 further includes a bearing mechanism with magnetic radial bearings, which can be designed, for example, as passive bearings and can have one or more stator bearing magnets 17 and one or more rotor bearing magnets 18. This or these stator bearing magnets 17 and this or these rotor bearing magnets 18 each include one or more permanent magnets, through whose cooperation the radial position of the rotor axis 19 corresponding to the symmetry axis of the rotor 8 is adjusted. In a preferred embodiment, the position of the rotor axis 19 is adjusted during the manufacture of the blood pump 2 as described below, such that the rotor axis 19 coincides with the symmetry axis (cylinder axis) of the flow channel 10 during operation. In this way, the distance 20 or the clearance width between the blades 11, 11' and the boundary 16 of the flow channel 10 can also be precisely set. In a preferred embodiment, this distance is less than 500 μm, for example 100 μm.

[0036] In some embodiments, the rotor 8 is also held and thus supported axially by the means shown. For this purpose, the electric motor 6 can also have a contact bearing 21 such as a point bearing or a spherical crown bearing, which restricts the movement of the rotor 8 in the flow direction 12 or in the direction opposite to the flow direction 12. It can also be provided that the stator bearing magnet 17 acts on the rotor bearing magnet 18 to axially preload the rotor 8, such that the rotor 8 is pressed against the contact bearing 21 especially in the stationary position, i.e., when the rotor 8 is not driven. The pressure exerted by the rotor 8 on the contact bearing 21 can be reduced during the operation of the blood pump 2 by the thrust of the rotor 8, such that the rotor 8 is supported axially without friction. The method for manufacturing the blood pump 2, which is also described in detail below, can preferably be applied to the passive magnetic radial bearings described here. But it can also be used, for example advantageously, for other bearing types provided additionally or alternatively, such as axial bearings. Furthermore, this manufacturing process can be advantageously used not only for axial pumps but also for radial pumps.

[0037] If permanent magnets (such as ring magnets) are used to manufacture the stator 13 or the rotor 8, deviations from the desired magnetic field distribution generated by these permanent magnets may occur. Especially when manufacturing a blood pump 2 with a small clearance width 20 in the flow channel 10 in the region of the rotor 8, such manufacturing tolerances should not be ignored. Deviations in the magnetic properties of the stator bearing magnets 17 used in the manufacture, for example, may cause the symmetry axis of the magnetic field generated by the stator bearing magnets 17 to be radially displaced relative to the geometric symmetry axis of the stator bearing magnets 17, i.e., not on the cylindrical axis of the flow channel 10, for example. Additionally, for example, if the rotor bearing magnet 18 deviates from its desired magnetic properties, the inertia axis or the geometric symmetry axis of the rotor 8 does not coincide with its magnetic center of gravity axis.

[0038] Such undesired deviations in the magnetic properties of the permanent magnets used can be corrected during the manufacture of the blood pump 2, as in Figures 3(a) to 3(c)As shown in the schematic diagram of axial direction. The flow channel 10 is defined by the inner wall 16 of the stator 13, and the rotor 8 is accommodated in the flow channel together with the conveying member. In the example shown, the inertia axis 22 of the rotor 8 coincides with its geometrical symmetry axis 19. If in other embodiments the inertia axis 22 of the rotor 8 does not coincide with its geometrical symmetry axis, that is, if there is a mechanical imbalance, the mass correction of the mechanical imbalance can be performed in a manner known per se. However, because the permanent magnets 18 used have the above-mentioned manufacturing tolerances, the inertia axis 22 of the rotor 8 usually does not coincide with the magnetic center of gravity axis 23 of the rotor 8, which leads to magnetic imbalance of the rotor 8.

[0039] When the electric motor 6 of the blood pump 2 is running at a low speed, the magnetic imbalance of the rotor 8 takes effect, so that the rotor 8 does not rotate about its inertia axis 22, but rotates about its magnetic center of gravity axis 23. This results in a time-dependent rotor position in the form of a swing, oscillation or shaking of the rotor 8, and the rotor 8 now moves along a circular trajectory in the pump tube, which is shown in FIG. 3(a) by the positions of the rotors 8', 8" swinging clockwise at different times in the example shown. If the rotor position is unstable, the offset, that is, the distance of the rotor 8 from the inner wall 16 of the stator 13 or the distance of the rotor 8 from the geometric symmetry axis 24 of the flow channel 10, is time-dependent due to the swinging motion of the rotor 8.

[0040] When manufacturing the electric motor 6 of the blood pump 2, the rotor 8 can first be arranged in the flow channel 10 defined by the inner wall 16 of the stator 13. The electric motor 6 can then be driven, for example, under conditions which correspond approximately to the conditions which exist therein during operation of the implantable blood pump 2. For example, when manufacturing the electric motor 6, a liquid can be conveyed through the flow channel for testing purposes. The rotor position can be monitored during the manufacture of the motor 6, for example by observation under a microscope or by using a distance measuring sensor, while the rotor 8 is driven in rotation.

[0041] In conjunction with observation of the oscillating motion of the rotor 8 at low rotational speed, a correction of the magnetic properties of the rotor bearing magnets 18 can be performed, as described in more detail below. By this correction, which can optionally include several repeated steps, the inertial axis 22 of the rotor 8 can be made consistent with the magnetic center of gravity axis 23 of the rotor 8. Once this consistency is achieved, the rotor 8 rotates around the common inertial and magnetic center of gravity axes 22, 23 at a low rotational speed, as shown in Figure 3 (b).

[0042] The rotational movement of the rotor 8 becomes self-stabilizing as the rotational speed increases, such that even without correcting the magnetic properties of the rotor bearing magnet 18, i.e., when the inertial axis 22 of the rotor 8 does not coincide with its magnetic center of gravity axis 23, the rotor 8 rotates about its inertial axis 22 at a higher speed. For example, when the blood pump 2 for blood conveyance is implanted in a patient's body, the rotor 8 rotates self-stably at the nominal rotational speed of the blood pump 2, i.e., the general operating rotational speed of the blood pump 2. In this case, for the rotor 8 to rotate self-stably at a high rotational speed, thus the situation shown in Fig. 3(b) also occurs, where the rotor 8 rotates about its inertial axis 22 at a stable rotor position.

[0043] When the rotor 8 rotates at a stable rotor position, due to the manufacturing tolerances of the magnetic properties of the stator 13 and especially the stator bearing magnet 17, it is possible that the rotational axis of the rotor 8 does not match the desired rotor position on the symmetry axis 24 of the flow channel 10. Therefore, in the case of a stable rotor position, a time-constant offset of the undesired rotor position related to the symmetry axis 24 of the flow channel 10 may be exhibited.

[0044] Then, based on the observation of the rotor position offset, correction of the magnetic properties of the stator 13 or the stator bearing magnet 17 can be carried out, and these steps can be repeated multiple times (observing the rotor position and then correcting the magnetic properties, observing the rotor position again, and so on). In particular, the steps of offset determination and correction can be repeatedly executed until the determined offset of the rotor 8 is lower than a specified theoretical value. By correcting the magnetic properties of the stator 13, the rotor 8 can be made to rotate about its inertial axis 22 to coincide with the symmetry axis 24 of the flow channel 10, as shown in Fig. 3(c). In this way, it can be ensured that when the electric motor 6 of the blood pump 2 operates at the nominal rotational speed, the size of the gap 20 is precisely defined, which is particularly useful in the small structural dimensions of the blood pump. The correction of the magnetic properties of the stator 13 can be carried out, for example, by fixing a magnetically effective material 25, especially a ferromagnetic material (such as a shim or a gasket), within a quarter quadrant of the stator 13, as schematically shown in Fig. 3(c). However, other possible ways for correcting the magnetic properties of the stator 13 are also described above and below.

[0045] The electric motor 6 shown in Fig. 3(b) is corrected not only in terms of the magnetic properties of the rotor 8 but also in terms of the magnetic properties of the stator 13. In the region of the rotor bearing magnet 18 and in the region of its cylindrical symmetry axis 19, the rotor 8 has a cylindrical bore 30 which, for example, is at least partially occupied on one half by a bar 26 made of magnetically effective material and on the other half by a bar 27 made of magnetically ineffective material. The magnetically effective material 26 generally comprises ferromagnetic material, for example it can be a semi-circular iron bar. By means of the magnetically effective material 26, when correcting the magnetic properties of the rotor 8, the magnetic center-of-gravity axis 23 of the rotor 8 is made to coincide with the inertia axis 22 of the rotor 8. The magnetically ineffective material 27 is provided such that no appreciable mechanical imbalance is created by the correction. The magnetically ineffective material 27 can, for example, be a counterweight and in particular has a density which is almost the same as that of the magnetically effective material 26, so that the correction of the magnetic properties can be carried out relatively simply without creating a mechanical imbalance. In the present example, the magnetically ineffective material 26 can be designed as a semi-circular bar made of non-magnetizable steel. In other embodiments, additionally or alternatively, when correcting the magnetic properties of the rotor 8, the existing magnetically active material of the rotor bearing magnet 18 can be removed in a local region of the circumferential surface of the rotor 8, i.e. non-rotationally symmetrically, or the magnetic properties can be changed (magnetized or demagnetized), for example by locally heating with a laser or a soldering iron.

[0046] In the example shown, the magnetic properties of the stator 13 are corrected by applying magnetically active material 25 to the outer side of the stator bearing magnet 17. Figure 4 It is shown that the magnetic properties of the stator bearing magnet 17 can be corrected very effectively and in a targeted manner. The correction 28 of the above-mentioned static offset of the rotor position in micrometers (μm) is plotted against the axial extent 29 of the 200-μm thick spacer 25, i.e. the displacement of the position of the inertia axis of the rotor 8 towards the symmetry axis 24 of the flow channel. With an axial extent of, for example, 4 mm of the spacer 4, a rotor position correction of approximately 60 μm can be produced, for example, in a targeted manner. In other embodiments for correcting the magnetic properties of the stator 13, additionally or alternatively, it is feasible that the existing magnetically active material of the stator bearing magnet 17 is removed in a local region of the circumferential surface of the stator 13, i.e. non-rotationally symmetrically, or the magnetic properties are changed (magnetized or demagnetized), for example by heating with a laser or a soldering iron.

[0047] The features of the embodiments disclosed only in the examples can be combined with one another and can be claimed separately.

Claims

1. A method of manufacturing a bearing mechanism for an implantable blood pump (2), the method comprising the following steps: - providing a rotor (8) having one or more drive magnets (15), wherein the rotor (8) has a conveying member (9), - providing a stator (13) having a stator winding, - arranging the rotor (8) in a flow channel (10) formed by the inner wall of the stator (13), - driving the rotor to rotate, - determining an offset of the rotor (8) during driving the rotor to rotate, - correcting the offset of the rotor (8) by applying, removing, magnetizing and / or demagnetizing a magnetically effective material on the stator (13) and / or the rotor (8) in a non-rotationally symmetric manner.

2. The method according to claim 1, wherein The bearing mechanism forms a passive magnetic bearing.

3. The method according to claim 1 or 2, characterized in that, During correction, the magnetically effective material is applied, removed, magnetized or demagnetized on the rotor (8).

4. The method according to claim 1, wherein The magnetically effective material is permanently magnetized and / or demagnetized during correction.

5. The method according to claim 1, wherein All steps of the method are not carried out in a human body or an animal body.

6. The method according to claim 1, the method comprising: - delivering a blood pump comprising a corrected bearing mechanism, and / or - aseptically packaging a blood pump comprising a corrected bearing mechanism.

7. The method according to claim 1, wherein The application, removal, magnetization and / or demagnetization of the magnetically effective material on the stator and / or the rotor are permanently maintained.

8. The method according to claim 1, characterized in that, The bearing mechanism comprises a magnetic radial bearing having one or more rotor bearing magnets (18) and one or more stator bearing magnets (17), wherein a radial offset of the rotor (8) is determined and subsequently reduced during driving the rotor to rotate.

9. The method according to claim 8, characterized in that The determination of the radial offset is performed when driving the rotor to rotate at a rotational speed at which the rotor (8) rotates substantially about its inertial axis (22), wherein subsequently the radial offset of the rotor (8) is reduced by applying, removing, magnetizing and / or demagnetizing a magnetically effective material on the stator (13) in a non-rotationally symmetric manner.

10. The method according to claim 8 or 9, characterized in that, The determination of the radial offset is performed when driving the rotor to rotate at a rotational speed at which the rotor (8) rotates substantially about its magnetic center of gravity axis, wherein the offset of the rotor (8) is corrected by applying, removing, magnetizing and / or demagnetizing a magnetically effective material on the rotor (8) in a non-rotationally symmetric manner.

11. The method according to claim 1, wherein During driving the rotor to rotate, the offset of the rotor (8) is determined by means of a microscope and / or by means of a distance measuring sensor.

12. The method according to claim 1, characterized in that The offset of the rotor (8) is corrected by applying or removing a magnetically effective material on the rotor (8) in a non-rotationally symmetric manner, and further removing a magnetically ineffective material (27) from the rotor (8) or applying a magnetically ineffective material (27) to the rotor (8) to correct a mechanical imbalance of the rotor (8).

13. The method according to claim 1, characterized in that, The offset of the rotor (8) is corrected by non-rotationally symmetric magnetization or demagnetization of the magnetically effective material on the rotor (8).

14. A bearing mechanism for an implantable blood pump (2), the bearing mechanism being manufactured by the method according to any one of claims 1 to 13, characterized in that, A magnetically effective material is applied on the rotor (8) and / or the stator (13) in a non-rotationally symmetric manner.

15. An implantable blood pump (2), the implantable blood pump (2) comprising an electric motor (6), the electric motor (6) having a rotor (8), a stator (13) and a bearing mechanism with a passive magnetic radial bearing, the bearing mechanism comprising at least one rotor bearing magnet (18) and at least one stator bearing magnet (17), characterized in that, There is provided magnetically effective material which is applied to the rotor (8) and / or the stator (13) in a non-rotationally symmetric manner to define and / or correct a radial offset of the rotor (8).

16. The implantable blood pump (2) according to claim 15, characterized in that, The radial offset of the rotor (8) is defined or corrected such that the geometric center-of-gravity axis of the rotor (8) coincides with the cylindrical symmetry axis of the flow channel (10) formed by the inner wall of the stator (13).

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