Abstract
A pump, such as a blood pump, includes a pump chamber with a wall and a fluid connection between an inlet and an outlet, along with an impeller, a motor stator, and a control coil arranged on the pump chamber for exerting, together with first rotor magnets, a controllable axial force on the rotor. A control unit provides a control current for the control coil, in order to hold the rotor in a position which is spaced apart axially from the wall of the pump chamber. A first chamber magnet is arranged close to the winding of the control coil and opposite the first rotor magnet, in order to provide, together with the first rotor magnet, a force between the first rotor magnet and the first chamber magnet, and in order to orient the rotor relative to the wall of the pump chamber.
Claims
1. A pump comprising: a pump chamber with a wall and a fluid connection for a fluid flow between an inlet and an outlet of the pump chamber; an impeller disposed in the pump chamber and coupled to a rotor, the impeller being configured to rotate about an axis of rotation that is aligned with the inlet and defines an axial direction, and is further configured to drive the fluid flow from the inlet to the outlet; a motor stator disposed at the pump chamber, the motor stator comprising at least one motor coil which is configured to provide a motor magnetic field to interact with a magnetic field of a motor magnet disposed on the impeller to rotationally drive the impeller; a control coil disposed at the pump chamber, wherein one or more turns of a winding of the control coil are disposed at the wall around the pump chamber, wherein the control coil is configured to generate a magnetic field by a control current, wherein the generated magnetic field exerts a controllable axial force on the rotor in the axial direction along with a first rotor magnet arranged on the rotor; a control unit providing the control current for the control coil, and to hold the rotor in a position spaced apart axially from the wall of the pump chamber; and a first chamber magnet, disposed at the pump chamber, close to the winding of the control coil and opposite the first rotor magnet, wherein the first chamber magnet is configured, along with the first rotor magnet to provide a force between the first rotor magnet and the first chamber magnet to align the rotor relative to the wall of the pump chamber.
2. The pump according to claim 1, the pump further comprising: a second magnetic bearing; a second chamber magnet, disposed at the pump chamber where the axis of rotation meets the wall; and a second rotor magnet disposed opposite the second chamber magnet at the rotor, wherein the second magnetic bearing is configured to provide a repelling force between the second rotor magnet and the second chamber magnet to maintain at least a portion of the rotor in a position spaced from the wall of the pump chamber in a radial direction perpendicular to the axial direction.
3. The pump according to claim 1, wherein the rotor has a recess around the axis of rotation and is configured to guide the fluid flow through the recess.
4. The pump according to claim 2, wherein the force between the first rotor magnet and the first chamber magnet comprises a force of attraction, wherein the first rotor magnet and the first chamber magnet form a first magnetic bearing that is configured to orient the rotor in a tilting direction which has an axis of rotation in the radial direction.
5. The pump according to claim 1, wherein the force between the first rotor magnet and the first chamber magnet comprises a repelling force in a radial direction which is perpendicular to the axial direction, wherein the first rotor magnet and the first chamber magnet form a first magnetic bearing that is configured to maintain the rotor in a position spaced apart from the wall of the pump chamber in the radial direction.
6. The pump according to claim 5, wherein the control coil comprises a magnetically conductive material arranged between the winding and the fluid connection or on a side of the control coil facing away from the rotor.
7. The pump according to claim 5, further comprising: a biasing magnet disposed at the control coil and configured to bias the magnetic field of the control coil.
8. The pump according to claim 4, wherein the second rotor magnet and the second chamber magnet are disposed relative to one another so that an axial force acts on the rotor in the axial direction away from the inlet, and a quotient of a radial rigidity of the second magnetic bearing to a radial rigidity of the first magnetic bearing in the event of rotor displacement in the axial direction, the radial direction or a tilting direction, which has an axis of rotation in the radial direction, remains substantially constant, wherein the radial rigidity of the first magnetic bearing is a result of the rigidity of the control coil and first chamber magnet with the first rotor magnet.
9. The pump according to claim 4, wherein a ratio between a radial rigidity of the second magnetic bearing and a radial rigidity of the first magnetic bearing is between 4:1 and 1.5:1.
10. The pump according to claim 1, wherein the motor magnet is arranged on a side of the impeller facing away from the inlet or on a side of the impeller facing the inlet.
11. The pump according to claim 1, wherein the control unit is configured to provide a motor coil current such that the motor magnetic field together with the magnetic field of the motor magnet creates a force in the axial direction between the motor magnet and the motor stator.
12. The pump according to claim 1, wherein the fluid flow comprises blood flow.
13. The pump according to claim 1, wherein the pump being used in a cardiac support system.
14. The pump according to claim 1, wherein parts of the control coil are arranged in axial direction in front of and behind the magnetic bearing pairs and.
15. The pump according to claim 14, wherein a second control coil is coupled to the control coil, and disposed in axial direction upstream and the second control coil in axial direction downstream of the first rotor magnet and the first chamber magnet.
16. The pump according to any claim 1, wherein the force between the first rotor magnet and the first chamber magnet is a repellent force in an axial direction, such that the rotor is held in a position spaced apart from the wall of the pump chamber in the axial direction.
17. The pump according to claim 4, wherein the force between the first rotor magnet and the first chamber magnet is additionally a repelling force in an axial direction, so that the rotor is held in a position spaced apart from the wall of the pump chamber in the axial direction.
18. A method for operating a pump, the method comprising: providing a motor magnetic field for driving an impeller connected to a rotor for driving a fluid flow from an inlet to an outlet of a pump chamber; providing, with a control coil and a first rotor magnet arranged on the rotor, a controllable axial force to the rotor in the direction of an axis of rotation of the rotor, which defines an axial direction; providing a control current for the control coil, to keep the rotor in a position spaced apart axially from a wall of the pump chamber, in a time-varying position, in which the sum of all forces on the rotor except the controllable axial force in the axial direction adds up to zero; and providing a force between the first rotor magnet and a first chamber magnet arranged on the pump chamber near a winding of the control coil.
19. The method for operating a pump according to claim 18, comprising one or more of the steps: guiding the fluid flow through a recess in the rotor about the axis of rotation of the rotor away from the inlet in the direction of the outlet; guiding the fluid flow, so that the fluid flow is guided though the inlet substantially in the axial direction and is guided through the outlet in a direction which has substantially no axial component; or guiding a secondary fluid flow between the first rotor magnet and the wall of the pump chamber or guiding a tertiary fluid flow between the motor magnet and the wall of the pump chamber.
20. The method for operating a pump according to claim 18, comprising: generating a repelling force between a second rotor magnet and a second chamber magnet arranged on the pump chamber, where the axis of rotation meets a wall of the pump chamber.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0059] FIG. 1A shows a schematic representation of a pump;
[0060] FIG. 1B shows a schematic representation of a rotor of the pump from FIG. 1A;
[0061] FIG. 2A shows a schematic representation of a pump;
[0062] FIG. 2B shows further details of the pump of FIG. 2A;
[0063] FIG. 3A-3G show schematic representations of a first section of the rotor and a control coil in a partial cross-sectional and partially perspective view;
[0064] FIG. 4 is a diagram showing an option for generating axial force as a function of an axial position of the rotor; and
[0065] FIG. 5 is a flow chart for a method for operating a pump.
DETAILED DESCRIPTION
[0066] Recurring elements in the Figures are denoted by the same reference signs and are partly omitted, particularly if no reference is made to these elements in relation to a specific drawing. It is also understood that the shown exemplary embodiments only represent options for implementing the disclosed inventive ideas and are not limiting in any way. All of the drawings are simply schematic or diagrammatic representations, even if this is not always explicitly indicated. Details which are not mentioned in the explanation may be omitted from the individual representations.
[0067] FIG. 1A shows a schematic representation of a pump 1, in particular a pump 1 with a magnetically mounted rotor 3. The pump may be a blood pump 1 and includes a magnetically mounted rotor 3. The representation in FIG. 1A is a cross-sectional view. The pump 1 has a pump chamber 2 which is delimited by a wall 2. The material from which the wall 2 is constructed can be metal, for example steel, in particular also stainless steel, or also titanium, for example also a titanium alloy or also a ceramic. In some applications however, the material of the wall 2 can also be for example a plastic or for example an alloy or a combination of some or more of the aforementioned materials. The wall 2 can be manufactured as multiple parts for example and assembled during the manufacture of the pump 1. The pump chamber 2 has an inlet 10 and an outlet 9 and a fluid connection 12, i.e. a volume in which fluid can flow, between the inlet 10 and the outlet 9. The inlet 10 is an opening in the wall 2 which is for supplying fluid into the pump chamber 2 and the outlet 9 is an opening in the wall 2 for discharging fluid from the pump chamber 2. For example, the fluid can be liquids or gases. In particular the fluid can be blood.
[0068] The pump 1 in FIG. 1A also comprises a rotor 3 which is configured to rotate about an axis of rotation 3. The axis of rotation 3 can be arranged for example in a central position of the inlet 10, i.e. aligned with the inlet 10. As explained above, it is assumed that the rotor only performs small translational movements, so that with the aim of providing a simpler and more understandable description, the axis of rotation can be regarded as fixed with respect to the pump chamber.
[0069] The axis of rotation 3 can also represent a kind of axis of symmetry for the pump 1, whose components shown in FIG. 1A are arranged substantially symmetrically thereto. The pump 1 and also the rotor 3 can have an essentially radially symmetrical form and arrangement with respect to the axis of rotation 3. Essentially means that the symmetry can also be deviated from locally.
[0070] The axis of rotation 3 defines an axial direction 21, which can be specified as axial axis 21 in a coordinate system. A radial direction 22 can be defined perpendicular to the axial direction 21 and entered in the coordinate system as the radial axis 22. A direction of rotation with an axis of rotation perpendicular to the axial axis 21 can be specified as a tilting direction 23.
[0071] As shown in FIG. 1A, a fluid flow 13, also a flow of fluid, for example blood, can be guided initially away from the inlet 10 through the fluid connection 12 in the axial direction 21. Furthermore, the fluid flow 13 can be guided to the outlet 9, for example in the radial direction 22. The fluid can finally leave the pump chamber 2 via the outlet 9. It is possible that the fluid flow 13 at the outlet 9 has essentially no component, i.e. no component of a fluid direction, in the axial direction 21.
[0072] In addition to the fluid flow 13, which represents a main flow of fluid through the pump 1, which is indicated by large arrows in FIG. 1A, a secondary fluid flow 13, for example a secondary blood flow 13, may be provided, wherein less fluid flows in the secondary fluid flow 13 than in the fluid flow 13, which is symbolized by small arrows in FIG. 1A. The secondary fluid flow 13 can be guided for example between the rotor 3 and wall 2, for example between a first rotor magnet 4 and the wall 2, in this case for example in the axial direction 21 to the inlet 10.
[0073] Furthermore, a tertiary fluid flow 13 can be provided, wherein less fluid flows in the tertiary fluid flow 13 than in the fluid flow 13, which is symbolized by small arrows in FIG. 1A. The tertiary fluid flow 13 can be guided for example between the rotor 3 and wall 2, for example between a motor magnet 11 and the wall 2, in this case for example in the radial direction 22 to the axis of rotation 3.
[0074] The secondary fluid flow 13 and tertiary fluid flow 13 can each have a different flow direction and can help to fill a space between the rotor 3 and wall 2 with fluid and keep the fluid there in motion. This can be used for example to reduce the risk of clumping of the fluid or, for example in the case of blood, reduce the risk of thrombosis.
[0075] Furthermore, FIG. 1A also shows an impeller 40. The impeller 40 can comprise for example blades and/or vanes, which are configured to drive the fluid flow 13, in particular on rotation of the impeller 40. The secondary fluid flow 13 and the tertiary fluid flow 13 can also be driven in this way respectively. The impeller 40 is coupled rigidly to the rotor 3 and rotates with the rotor 3 on rotation of the rotor 3. The impeller 40 has a substantially disc-like form in FIG. 1A. This means that its expansion in the axial direction 21 is smaller than in the radial direction 22, wherein an imaginary envelope (not shown) of the impeller 40 is substantially disc-like, i.e. is flat. A semi-axial impeller arrangement is also possible, which includes an axial portion and the flow direction is not abruptly changed from substantially axial to substantially non-axial.
[0076] The motor magnet 11 is arranged adjacent to the impeller 40. The motor magnet 11 can include a plurality of motor magnets. The motor magnet 11 can be a permanent magnet, for example a rare-earth magnet, e.g. NdFeB or SmCo. Furthermore, a magnetization direction of the motor magnet 11 can extend in the axial direction 21. In the case of a plurality of motor magnets 11 it is possible for neighboring motor magnets 11 to have a different direction of magnetization in each case. Other magnetization directions, for example a tangential or a radial magnetization direction, are also conceivable. It is also conceivable that the motor magnets are located in the vanes of the impeller.
[0077] The motor magnet 11 is shown opposite the motor stator 11. The motor stator 11 can comprise one or more motor coils (not shown). Furthermore, the motor stator 11 is arranged at the wall 2, for example integrated into the wall 2 or, starting from the pump chamber 2, positioned behind the wall 2. The motor stator 11 is configured to generate a magnetic field with the motor coils, through which an electric current can flow, which can for example have a component in the axial direction 21, and which is further configured to interact with the magnetic field of the motor magnet 11 in order to rotationally drive the impeller 40. In such a case, the impeller 40 can rotate about the axis of rotation 3, for example together with the rotor 3.
[0078] FIG. 1A also shows the first rotor magnet 4. The first rotor magnet 4 can be a permanent magnet for example, and it can be arranged in a ring at a distance around the axis of rotation 3 in or also at the rotor 3. The magnetization direction of the first rotor magnet 4 can be provided for example in the radial 22 or in the axial direction 21. It can also be divided into one or more sections, for example in the axial direction 21, each with its own magnetization. The magnetization direction of the various sections can differ from one another, for example in opposite directions. In principle also other arrangements are conceivable, such as an arrangement as a ring-shaped Halbach array, in which the magnetization direction of individual sections of the Halbach array can change in relation to each other.
[0079] A first chamber magnet 4 is arranged at the wall 2 at a radial distance from the first rotor magnet 4 and opposite this. The first chamber magnet 4 is arranged in the vicinity of a control coil 6. The first chamber magnet 4 can also be arranged in a ring at a distance about the axis of rotation 3. The magnetization direction of the first chamber magnet 4 can be provided for example in the radial direction 22 or in the axial direction 21. It can also be divided into one or more sections, for example in the axial direction 21, each with its own magnetization. The magnetization direction of the various sections can differ from one another, for example in opposite directions. In principle also other arrangements are conceivable, such as an arrangement as a ring-shaped Halbach array, in which the magnetization direction of individual sections of the Halbach array can change in relation to each other. The chamber magnet can also be spaced axially from the rotor magnet which creates an axial force on this bearing. The force can for example quasi-statically counteract the force of attraction of the flow-directing elements 7 around the control coil 6 or reinforce this force of attraction.
[0080] The magnetization of the first rotor magnet 4 and the first chamber magnet 4 is performed in this example so that they both repel one another.
[0081] In FIG. 1A the first rotor magnet 4 and the first chamber magnet 4 together form a first magnetic bearing 81. The first magnetic bearing 81 in the case shown in FIG. 1A is a permanent magnetic bearing or a passive magnetic bearing.
[0082] FIG. 1A also shows a second rotor magnet 5. The second rotor magnet 5 can be a permanent magnet for example and it can be arranged in a ring around an inner circumference 41 of the impeller 40 at a distance around the axis of rotation 3. The magnetization direction of the second rotor magnet 5 can be provided for example in the radial direction 22 or in the axial direction 21. It can also be divided into one or more sections, for example in the axial direction 21, each with its own magnetization. The magnetization direction of the various sections can differ from one another, for example in opposite directions. In principle also other arrangements are conceivable, such as an arrangement as a ring-shaped Halbach array, in which the magnetization direction of individual sections of the Halbach array can change in relation to each other.
[0083] A second chamber magnet 5 is arranged opposite the second rotor magnet 5 at the wall 2. The second chamber magnet 5 can also be ring-shaped or cylindrical for example. It is possible to arrange the second chamber magnet 5 so that the axis of rotation 3 runs through the second chamber magnet 5. The axis of rotation 3 can be aligned with a cylindrical axis of the second chamber magnet 5, in particular if the second chamber magnet 5 has cylindrical or a ring-shaped form, for example in the form of a hollow cylinder. The magnetization direction of the second chamber magnet 5 can be provided for example in the radial direction 22 or the axial direction 21. It can also be divided into one or more sections, for example in the axial direction 21, each with its own magnetization. The magnetization direction of the various sections can differ from one another, for example in opposite directions. In principle also other arrangements are conceivable, such as an arrangement as a ring-shaped Halbach array, in which the magnetization direction of individual sections of the Halbach array can change in relation to each other.
[0084] The magnetization of the second rotor magnet 5 and the second chamber magnet 5 is performed in this example so that they both repel one another.
[0085] First rotor magnet 4, second rotor magnet 5, first chamber magnet 4 and second chamber magnet 5 can be made with neodymium magnets for example.
[0086] In this example, the second rotor magnet 5 and the second chamber magnet 5 together form a second magnetic bearing 82. In the case shown in FIG. 1A, the second magnetic bearing is a permanent magnetic bearing or a passive magnetic bearing.
[0087] In a first variant, the magnetization of the chamber magnet 4 points substantially in the direction of the rotor magnet 4, whereas the magnetization of the rotor magnet 4 points in the direction of the chamber magnet 4. In this case, the first magnetic bearing is both radially and axially repelling, whereby the first magnetic bearing is axially unstable and radially stable. The second magnetic bearing can be magnetized in the same way: The magnetization of the second chamber magnet 5 points radially outwards, whereas the magnetization of the second rotor magnet points inwards so that the magnetizations of the two magnets are directed substantially towards one another.
[0088] In a second variant, the magnetization of the first chamber magnet and the magnetization of the first rotor magnet are directed upstream (or downstream) essentially parallel to one another. In this case, the first magnetic bearing is both radially and axially repelling, whereby the first magnetic bearing is axially unstable and radially stable. Likewise, the second magnetic bearing can also be magnetized such that the magnetizations of the second rotor and the second chamber magnet are parallel to one another and point in essentially the same direction as the magnetization of the first magnetic bearing.
[0089] The two aforementioned variants can also be combined with one another, i.e. the first magnetic bearing is configured according to the first variant, the second magnetic bearing according to the second variant or vice versa.
[0090] In a third variant, both the first (or second) chamber magnet and the first (or second) rotor magnet can be configured as a squeeze-field magnet, i.e. the magnetization of the upstream half of the respective magnet point downstream and the downstream half points upstream. To increase the rigidity of the magnetic bearing a plurality of squeeze-field pairs can be formed in succession in axial direction. In this case, the first (or second) magnetic bearing is both radially and axially repelling, wherein the first (or second) magnetic bearing is axially unstable and radially stable.
[0091] FIG. 1A also shows the control coil 6. In the representation shown, the control coil 6 is arranged completely between the inlet 10 and the rotor 3, as viewed in the axial direction 21. One turn of a winding of the control coil 6 is guided around the fluid connection 12 and thus around the pump chamber 2 at a distance from the axis of rotation 3, i.e. around the axial direction 21. A magnetic field that can be generated by the control coil 6 can have a component in the axial direction 21. The magnetic field of the control coil 6 is also configured to interact with a magnetic field of the first rotor magnet 4 and to exert an axial force on the rotor in the axial direction 21. The magnetic field of the control coil 6 can be generated by a control current. The axial force on the rotor 3 can be controlled by the control current for example.
[0092] A magnetic material 7 is also shown adjacent to the control coil 6 in FIG. 1A. The magnetic material 7 is used for guiding the magnetic field generated by the control coil and guides an associated magnetic flow, so that a greater axial force can be generated than without the magnetic material 7. Further details of the arrangement of the magnetic material 7 will be considered in more detail in the discussion of FIGS. 3A-3G. The magnetic material 7 can be integrated into the wall 2 and/or form a part of the wall 2 and/or also be arranged at the wall 2.
[0093] In an alternative variant to the positioning of the control coil shown in FIG. 1A, the control coil can have one part which is arranged upstream of the first chamber magnet and one further part that is arranged downstream of the first chamber magnet. Alternatively, two separate control coils can also be arranged in this way. Here it is advantageous, if the downstream part or the second control coil is arranged upstream of the second chamber magnet or in the vicinity of the first chamber magnet. The control coil can generate a magnetic field which is suitable for example for generating a magnetic field in a first magnetic bearing made up of squeeze-field magnets, which improves or enables axial positioning of the rotor.
[0094] In addition, FIG. 1A also shows a control unit 60. The control unit 60 can provide a control current for the control coil 6. The control current can be used for example to control a strength of the magnetic field of the control coil 6. This can ultimately be used to control the axial force on the rotor 3, which can be generated by the interaction of the magnetic field generated by the control coil 6 and the magnetic field of the first rotor magnet 4. The control current can thus be provided in such a way that the rotor 3 is held in a position spaced axially from the wall 2 of the pump chamber 2, for example in that the control current is large enough in each case to generate an axial force which is necessary to hold it in the axially spaced position. Forces on the rotor can be forces for example which are caused by the effect of the magnetic fields of the first rotor magnet 4, the second rotor magnet 5, the first chamber magnet 4 and the second chamber magnet 5 and/or also external forces on the rotor 3, for example based on the fluid flow 13, gravitation and/or an accelerated movement of the pump 1.
[0095] The control unit 60 can be configured for example as a microcontroller, a digital signal processor, an FPGA, or ASIC or also a combination thereof and can also contain other electronic components. These may also include sensors for example, such as for example a distance or also position sensor, for example for determining a position of the rotor 3, for example in the axial direction 21. Other possible sensors include for example a magnetic field sensor, a speed sensor, a pressure sensor, a fluid flow sensor and the like.
[0096] The control unit 60 can also be used to control the motor stator 11, for example by supplying the motor coil of the motor stator 11 with an electric current from the control unit 60, for example a time-varying electric current. For example, this electric current can be such that a magnetic field suitable for a rotary drive of the pump 1 is generated, wherein the magnetic field of the motor coil can interact with the magnetic field of the motor magnet for this purpose. However, the current provided by the control unit 60 for the motor stator 11 can also be configured to generate an axial force in the axial direction 21 on the rotor 3, also in cooperation with the motor magnet 11. For this purpose, the control unit 60 can comprise a controller which operates for example according to the principle of a field-operated control. The axial force generated by the motor stator 11 with the motor magnet 11 can be coordinated with the generation of the axial force by the control coil 6 with the first rotor magnet 4. It is possible for example to configure the axial force generated by the motor, comprising the motor stator 11 and motor magnet 11, as a biasing force for the axial force generated by the control coil 6. For example the biasing force can be speed-dependent.
[0097] FIG. 1B shows a cross-sectional representation of the rotor 3 from FIG. 1A. Here the rotor 3 has a first section 31 and a second section 32. For example, the first motor magnet 4 is arranged in the first section 31. In the second section 32 the impeller 40 is shown as well as the motor magnet 11 and the second rotor magnet 5. In this respect the first section 31 comprises the first magnetic bearing 81 and the second section comprises the second magnetic bearing 82 and the impeller 40. The rotor can be fully supported in the radial direction 22 by the first and the second magnetic bearing 81, 82. The first and second magnetic bearings 81, 82 are spaced apart from one another in axial direction. This means for example that a movement of the rotor 3 in the tilting direction 23 can also be at least partially suppressed.
[0098] The rotor 3 also has a recess 8 arranged around the axis of rotation 3 (not shown in FIG. 1A for reasons of clarity). For example, the recess 8 can be radially symmetrical about the axis of rotation 3, for example in the form of a bore. The recess 8 has the advantage that the fluid can be guided through it. Thus it is possible for example to keep the distance between the first rotor magnet 4 and the first chamber magnet 4 as small as possible, as the fluid does not have to be guided between the first rotor magnet 4 and the first chamber magnet 4, but can flow through the recess 8. This allows the distance-dependent magnetic forces between the first rotor magnet 4 and the first chamber magnet 4 to be as great as possible. In addition, the magnets themselves can be kept small and thus the installation space of the pump 1 can be kept small. Viewed in radial direction, a cross-section of the recess 8 can correspond for example or also essentially correspond to a cross-section of the inlet 10 in terms of the form and area with the aim of minimizing the flow resistance for the fluid through the pump 1. Here is also possible that the cross-sections of the recess 8 and inlet 10 are aligned relative to one another, as indicated in FIG. 1A.
[0099] Both the first section 31 and the second section 32 can comprise the recess 8 and in this way guide the fluid towards the impeller 40, so that it can flow from there to the outlet 9 or can be driven there by the impeller 40.
[0100] FIG. 2A shows a schematic representation of a pump 1 according to the present disclosure which has a number of similarities with the pump 1 shown in FIG. 1A, which will not be discussed again here. Rather, the differences from the pump 1 shown in FIG. 1A are not discussed here. Thus in the pump 1 shown in FIG. 2A, also in a cross-sectional view, the motor stator 11 is arranged at the pump chamber 2 on one side of the impeller 40 facing the inlet 10. The motor magnets 11 are arranged opposite in the axial direction at the impeller 40. The motor magnets 11 and motor stator 11 differ here from the example shown in FIG. 1A only with regard to their arrangement in the pump 1, but not with regard to their function and the further details described above.
[0101] Furthermore, in FIG. 2A the first rotor magnet 4 is arranged in the vicinity of an outer circumference of the impeller 40, in this case on a side of the impeller 40 facing away from the inlet 10. The first chamber magnet 4 is spaced apart radially from the first rotor magnet 4 at the wall 2 of the pump chamber 2. The first chamber magnet 4 is adjacent to the winding of the control coil 6. The winding of the control coil 6 is arranged between the first chamber magnet 4 and the pump chamber 2. One turn of the winding is guided around the pump chamber 2 in the axial direction 21. This enables a high efficiency of the control coil 6, wherein this refers to a high force effect that can be generated (together with the first rotor magnet 4) per unit of the electrical control coil current. As shown, in contrast to FIG. 1A, the control coil 6 is therefore not arranged in the vicinity of the inlet 10 but in the vicinity of the outlet or in the vicinity of the impeller. However, the control coil 6, together with the first rotor magnet 4, can also exert a force on the rotor 3 in the axial direction 21. Furthermore, due to the distance of the first rotor magnet 4 and the control coil 6 from the axis of rotation 3, the force generated by the first rotor magnet 4 and the control coil 6 can reduce a movement of the rotor 3 in the tilting direction 23.
[0102] This is also the task of the first rotor magnet 4 together with the first chamber magnet 4, whose magnetic fields interact and generate a force on the rotor. In this example this force can be a force of attraction between the first rotor magnet 4 and first chamber magnet 4. In principle, the force generated in this way can also act on the rotor 3 in the axial direction 21 and in the tilting direction 23.
[0103] The second rotor magnet 5 and the second chamber magnet 5 are substantially similar to the corresponding elements of FIG. 1A. In FIGS. 2A and 2B, the first rotor magnet 4 and the second rotor magnet 5 are configured as separate magnets. For example the advantage here is that the magnetization of both rotor magnets can be different according to polarization and/or strength and thus the respective forces acting in the first magnetic bearing 81 or in the second magnetic bearing 82 can be configured independently of one another.
[0104] In addition, it is also possible that the second rotor magnet 5 and the first rotor magnet 4 are combined into a single rotor magnet. This is possible for example if both have a correspondingly coordinated magnetization. This is shown in FIG. 2B for example.
[0105] In FIG. 2B, which is based on FIG. 2A, the rotor or chamber magnets 4, 4, 5, 5 shown each have several sections in the axial direction 21. Each of the sections shown has a magnetization, shown by arrows in the representations of the respective magnets 4, 4, 5, 5, in the axial direction 21, wherein in principle a magnetization in the radial direction 22 would also be conceivable in each case. However, the magnetization in the axial direction 21 facilitates the manufacture of the magnets and the assembly of the pump 1. Here in the example shown, due to the respective direction of the arrow it is clear that the first rotor magnet 4 and the second rotor magnet 5 each have identically magnetized sections in the axial direction 21, which means that the first and the second rotor magnet 4, 5 can be replaced by a single magnet, for example divided into the axial sections shown. An alternating magnetization of the first rotor magnet 4 and second rotor magnet 5 is also conceivable.
[0106] FIGS. 3A to 3G show schematic representations of the first section 31 of the rotor 3 and the control coil 6 in a cross-sectional view and in part a perspective view and thus continue the example from FIGS. 1A and 1B. Relative directions are adopted, as defined in FIGS. 1A and 1B. Details that are not shown correspond substantially to the representations in FIGS. 1A and 1B. In particular, FIGS. 3A to 3G show respectively the rotor 3, the first rotor magnet 4 and the first chamber magnet 4, the control coil 6 and the magnetic material 7.
[0107] FIG. 3A shows a possible arrangement of the magnetically conductive material 7, and in each case at the control coil 6, wherein the magnetically conductive material 7 is placed on the side of the control coil 6 facing the inlet 10 and on the side of the control coil 6 facing the fluid connection 12, i.e. between the fluid connection 12 and control coil 6, and is also placed here adjacent to the winding of the control coil 6. Turns of a winding of the control coil are guided around the fluid connection 12. One turn of the winding is thus also guided about the axial direction 21. The side of the control coil 6 facing away from the fluid connection 12 and the side of the control coil 6 facing the rotor 3 are not provided with the magnetically conductive material 7. The magnetic field generated by the control coil 6 can be conducted in the magnetically conductive material 7, which increases the magnetic flow density in the gap to the rotor magnet 4. This means that for the same control current a greater local magnetic flow density and therefore also a greater axial force can be generated between the control coil 6 and rotor 3. This is case for example in FIG. 3A at the point where the magnetically conductive material 7 comes closest to the rotor 3 or in this case also the first rotor magnet 4. The axial force effect is greatest in this area.
[0108] The advantages of this arrangement of the magnetically conductive material 7 are that with a given control current in the gap to the rotor 3, a greater magnetic flow density can be obtained than without magnetically conductive material 7, so that the desired axial force effect between the control coil 6 and rotor 3 can be increased at the desired point. For example, as explained above, a magnetically conductive material 7 can have a high relative magnetic permeability such as a ferromagnetic material, for example iron. Typical values for the relative magnetic permeability of ferromagnetic materials can be in the range of 300 and 10000 for example, wherein for certain materials, such as for example mu-metals, amorphous metals or also nanocrystalline metals, values significantly higher than this are known, for example of up to 150000 or even up to 500000. Lower relative magnetic permeabilities are also known for certain materials, which can drop to around 4 with ferrites for example.
[0109] FIG. 3A also shows an offset between the first rotor magnet 4 and the first chamber magnet 4 in the axial direction 21. With such an offset it is possible for example to generate an axial biasing force which is directed away from the inlet 10 for example. This can be used advantageously to reduce the amount of stationary force provided by the control coil 6 and the first rotor magnet 4 in the axial direction and for example to thus increase the efficiency of the pump 1.
[0110] FIG. 3A shows a variant of FIG. 3A, wherein here, in addition to FIG. 3A, the magnetically conductive material 7 is also placed on the side of the control coil 6 facing away from the fluid connection 12. The magnetically conductive material 7 can for example have a different material thickness in the radial direction 22 on the side of the control coil 6 facing the fluid connection 12 than on the side of the control coil 6 facing away from the fluid connection 12. For example, as shown here, (as viewed in radial direction 22) the material thickness of the magnetically conductive material 7 on the side of the control coil 6 facing the fluid connection 12 may be greater than on the side of the control coil 6 facing away from the fluid connection 12. The ratio of the material thicknesses can for example be such that a cross-sectional area of the magnetically conductive material 7 on the side of the control coil 6 facing the fluid connection is approximately equal to a cross-sectional area of the magnetically conductive material 7 on the side of the control coil facing away from the fluid connection, wherein the cross-sectional area is viewed perpendicular to the axial direction. The advantage of this is that the magnetic material is used as uniformly as possible with regard to a material-specific maximum magnetic flow density to be considered.
[0111] Based on FIG. 3B, FIG. 3C shows a further variant of the arrangement of the magnetically conductive material 7. In FIG. 3C in addition to the arrangement in FIG. 3B magnetically conductive material 7 is also arranged on the side of the control coil 6 facing the rotor 3. The magnetically conductive material 7 can be arranged such that the gap between the rotor 3 and control coil 6 is not enlarged compared to the example in FIG. 3B, for example in which only a portion of the side of the control coil 6 facing the rotor 3 is provided with magnetically conductive material 7. For example, a section of the side of the control coil 6 facing the rotor 3, which is directly opposite the rotor 3, is free of magnetically conductive material 7. With this arrangement the force effect can be further focused and it is also possible to further increase the magnetic flow, in particular in the gap between the rotor 3 and control coil 6, compared to the arrangement in FIG. 3C.
[0112] FIG. 3D shows a further arrangement of the magnetically conductive materials 7 similar to FIG. 3A. In addition, to the arrangement in FIG. 3A however there is section of magnetically conductive material 7 that is positioned in the rotor 3 on a side facing the inlet 10 and adjacent to the first rotor magnet 4. In this case, the magnetically conductive material 7 can be configured as an iron yoke for example and can further concentrate the magnetic flow.
[0113] FIG. 3E shows for example a combination of the examples from FIGS. 3B and 3D. It is clear that the above examples of the arrangement of the magnetically conductive material 7 can be combined as desired. This also applies in the same way to FIG. 3F, which is based on FIG. 3E, where the control coil 6 has the outer form of truncated cone compared to the previous examples. This shows, inter alia, that the control coil 6 can be formed with different geometries, which also includes geometries not shown, such as a cuboid geometry or also generally a cylindrical geometry, which also includes a ring-shaped geometry, with a polygonal base.
[0114] A further example, again with a substantially cylindrical geometry, is shown in FIG. 3G. The example shown in FIG. 3G is based on the example in FIG. 3B, wherein magnetically conductive material 7 is arranged on the side of the control coil 6 facing the inlet 10. Instead of this however, a biasing magnet 6, for example a permanent magnet, is arranged there adjacent to the control coil 6. In the example of FIG. 3G the magnetically conductive material 7 adjoins the biasing magnet 6 in the radial direction 22 on an inner and an outer circumference of the annular biasing magnet 6 in this example. The magnetization of the biasing magnet 6 can be performed here in the radial direction 22 for example. Configured as a permanent magnet, the biasing magnet 6 can for example provide a magnetic flow without requiring an electrical control current through the winding of the control coil 6. Thus, for example an operating point of the control coil 6 together with the first rotor magnet 4 can be set with regard to the magnetic flow and/or the axial force.
[0115] FIG. 4 shows a diagram for the option of axial force generation as a function of an axial position of the rotor 3 and relates mainly to the example in FIGS. 1A and 1B, but can be adapted in an analogous manner to the example in FIGS. 2A and 2B. The possibility is considered that both the motor which comprises the motor stator 11 with the motor coil and the motor magnet 11, and the control coil 6, when it interacts with the first rotor magnet 4, can generate an axial force acting in the axial direction 21 on the rotor 3. The motor 11, 11 and control coil 6 with the first rotor magnet 4 can be synchronized in their function so that the total axial force generated is substantially constant. This is symbolized by the constant horizontal dash-dot line in FIG. 4. This is advantageous, as in this way the axial position of the rotor 3 can be controlled more easily.
[0116] The solid, rising line in the diagram of FIG. 4 relates to the force generated by the control coil 6 together with the first rotor magnet 4 in the axial direction. It increases (with the same control current) the closer an axial position of the rotor 3 approaches the inlet 10.
[0117] The dashed, descending line in the diagram in FIG. 4 refers to the force generated by the motor in the axial direction. It decreases (with otherwise identical motor control) the closer an axial position of the rotor 3 approaches the inlet 10.
[0118] FIG. 5 shows a flow chart for a method for operating a pump 1. The method comprises the steps: [0119] S1: Providing a motor magnetic field for driving an impeller 40 connected to a rotor 3 for driving a fluid flow 13 from an inlet 10 to an outlet 9 of a pump chamber 2; [0120] S2: Providing, with a control coil 6 and a first rotor magnet 4 arranged at the rotor 3, a controllable axial force on the rotor 3 in the direction of an axis of rotation 3 of the rotor 3, which defines an axial direction 21; [0121] S3: Providing a control current for the control coil 6, to maintain the rotor 3 in a position spaced axially from a wall 2 of the pump chamber 2, such as in a time-varying position, in which the sum of all forces on the rotor 3 except the controllable axial force in the axial direction 21 adds up to zero; [0122] S4: Providing a force between the first rotor magnet 4 and a first chamber magnet 4 arranged at the pump chamber 2 near a winding of the control coil 6.
[0123] The said steps can be carried out in this order but can also be carried out in a different order. Individual or several of the steps can also be performed multiple times.
[0124] As part of the method, a zero force control may be used, in which a particularly small control current is required, since the rotor 3 is held in the position which may vary over time in which the sum of all forces on the rotor 3 except the controllable axial force in the axial direction 21 adds up to zero. This enables an efficient operation of the pump 1 with minimized electrical control power.
LIST OF REFERENCE SIGNS
[0125] 1 pump [0126] 2 pump chamber [0127] 2 wall [0128] 3 rotor [0129] 3 axis of rotation [0130] 4 first rotor magnet [0131] 4 first chamber magnet [0132] 5 second rotor magnet [0133] 5 second chamber magnet [0134] 6 control coil [0135] 6 biasing magnet [0136] 7 magnetically conductive material [0137] 8 recess [0138] 9 outlet [0139] 10 inlet [0140] 11 motor stator [0141] 11 motor magnet [0142] 12 fluid connection [0143] 13 fluid flow [0144] 13 secondary fluid flow [0145] 13 tertiary fluid flow [0146] 21 axial direction [0147] 22 radial direction [0148] 23 tilting direction [0149] 31 first section (of the rotor) [0150] 32 second section (of the rotor) [0151] 40 impeller [0152] 41 inner circumference of the impeller [0153] 60 control unit [0154] 81 first magnetic bearing [0155] 82 second magnetic bearing
