(19)
(11)EP 1 677 856 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
26.06.2019 Bulletin 2019/26

(21)Application number: 04783894.1

(22)Date of filing:  14.09.2004
(51)International Patent Classification (IPC): 
A61M 1/10(2006.01)
F04D 13/06(2006.01)
(86)International application number:
PCT/US2004/029842
(87)International publication number:
WO 2005/028000 (31.03.2005 Gazette  2005/13)

(54)

ROTARY BLOOD PUMP

ROTIERENDE BLUTPUMPE

POMPE SANGUINE ROTATIVE


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PL PT RO SE SI SK TR

(30)Priority: 18.09.2003 US 504233 P

(43)Date of publication of application:
12.07.2006 Bulletin 2006/28

(60)Divisional application:
19176291.3

(73)Proprietor: TC1 LLC
St. Paul, MN 55117 (US)

(72)Inventors:
  • WAMPLER, Richard
    Loomis, CA 95650 (US)
  • LANCISI, David
    Folsom, CA 95630 (US)

(74)Representative: Dolleymores 
9 Rickmansworth Road
Watford, Hertfordshire WD18 0JU
Watford, Hertfordshire WD18 0JU (GB)


(56)References cited: : 
US-A- 5 106 273
US-A- 6 155 969
US-B1- 6 368 083
US-A- 5 695 471
US-A1- 2003 091 450
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    FIELD OF THE INVENTION



    [0001] This invention relates to the field of rotary pumps. In particular, this invention is drawn to bearings for various rotor and impeller architectures.

    BACKGROUND OF THE INVENTION



    [0002] Typical rotary pumps utilize an impeller wherein the movement of the impeller is constrained in five degrees of freedom (two angular, three translational) by mechanical contact bearings. Some working fluids may be damaged by the mechanical contact bearings. Blood pumped through pumps with contact bearings can experience hemolysis, i.e., damage to blood cells. In general, a hydraulically efficient and power efficient pump that can handle delicate working fluids such as blood is desirable for some applications.

    [0003] U.S. Patent No. 6,234,772 B1 of Wampler, et al., ("Wampler") describes a centrifugal blood pump having a repulsive radial magnetic bearing and an axial hydrodynamic bearing. U.S. Patent No. 6,250,880 B1 of Woodard, et al. ("Woodard") describes a centrifugal blood pump with an impeller supported exclusively by hydrodynamic forces.

    [0004] Both blood pumps are based on an axial flux gap motor design. The pump impeller carries the motor drive magnets thus serving as a motor rotor. In both cases, the drive magnets are disposed within the blades of the impeller. Drive windings reside outside the pump chamber but within the pump housing that serves as the motor stator. Integration of the motor and pump enables the elimination of drive shafts and seals for the pumps. The pump/motors include a back iron to increase the magnetic flux for driving the impeller.

    [0005] Both blood pumps suffer from hydraulic inefficiencies due at least in part to the large, unconventional blade geometry required for disposing the magnets within the impeller blades.

    [0006] The natural attraction between the magnets carried by the impeller and the back iron creates significant axial forces that must be overcome in order for the pump to work efficiently. Hydrodynamic bearings can damage blood cells as a result of shear forces related to the load carried by the hydrodynamic bearings despite the lack of contact between the impeller and the pump housing. Thus exclusive reliance on hydrodynamic bearings may be harmful to the blood.
    US5106273 discloses a pump designed for pumping gas. US2003/091450 discloses a pump having a number of magnetic bearings, including an electrodynamic bearing.

    SUMMARY OF THE INVENTION



    [0007] In view of limitations of known systems and methods, various "contactless" bearing mechanisms are provided for a rotary pump as alternatives to mechanical contact bearings. Various rotor and housing design features are provided to achieve magnetic or hydrodynamic bearings. These design features may be combined. The lack of mechanical contact bearings enables longer life pump operation and less damage to working fluids such as blood. The invention is defined by the appended claims.

    [0008] In one embodiment, the pump includes a magnetic thrust bearing. The pump includes a pump housing defining a pumping chamber. The pump housing has a spindle extending into the pumping chamber. A spindle magnet assembly comprising first and second magnets is disposed within the spindle. The first and second magnets of the spindle magnet assembly are arranged proximate each other with their respective magnetic vectors opposing each other. The pump includes a rotor having an impeller configured to rotate about the spindle. A rotor magnet assembly comprising first and second magnets is disposed within a non-bladed portion of the rotor. The first and second magnets of the rotor magnet assembly are arranged proximate each other with their respective magnetic vectors opposing each other. The relative orientations of the spindle and rotor magnet assemblies are selected so that the spindle and rotor magnet assemblies attract each other. The rotor may include a grooved bore. In various embodiments, a hydrodynamic bearing is included for radial or axial support or both.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0009] The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:

    Figure 1 illustrates a cross-section of a pump having a passive magnetic axial bearing.

    Figure 2 illustrates one embodiment of the passive magnetic axial bearing.

    Figure 3 illustrates center and off-center placement of the passive magnetic axial bearing.

    Figure 4 illustrates one embodiment of an impeller.

    Figure 5 illustrates one embodiment of the pump applied in a medical application.


    DETAILED DESCRIPTION



    [0010] Figure 1 illustrates one embodiment of a centrifugal blood pump. The pump comprises a housing 110 defining a pumping chamber 112 between an inlet 114 and an outlet 116. Within the pumping chamber, a rotor 120 rotates about a spindle 130 protruding from a base of the pump housing. The rotor further comprises a bladed portion defining an impeller that provides the fluid moving surfaces. The impeller comprises one or more blades 121 that move fluids when the impeller rotates.

    [0011] The terms "rotor" and "impeller" may be used interchangeably in some contexts. For example, when the rotor is rotating, the blade portion of the rotor is inherently rotating such that reference to rotation of either the impeller or the rotor is sufficient to describe both. When necessary, however, the term "non-bladed portion of the rotor" or "rotor excluding the impeller" may be used to specifically identify portions of the rotor other than the blades. Each blade of the rotor may separately be referred to as an impeller, however the term "impeller" is generally used to refer to a collective set of one or more blades.

    [0012] The pump is based upon a moving magnet axial flux gap motor architecture. In one embodiment, the motor is a brushless DC motor. Drive magnets 122 carried by the rotor have magnetic vectors parallel to the rotor axis of rotation 190. In the illustrated embodiment, the drive magnets are disposed within a non-bladed portion of the rotor.

    [0013] Drive windings 140 are located within the pump housing. Power is applied to the drive windings to generate the appropriate time-varying currents that interact with the drive magnets in order to cause the impeller to rotate. A back iron 150 enhances the magnetic flux produced by the motor rotor magnets. In one embodiment, either the face 124 of the bottom of the rotor or the opposing face 118 provided by the lower pump housing have surfaces (e.g., 172) contoured to produce a hydrodynamic bearing when the clearance between the rotor and the housing falls below a pre-determined threshold. In one embodiment, the pre-determined threshold is within a range of 0.0002 inches to 0.003 inches.

    [0014] The natural attraction between the back iron 150 and the drive magnets 122 carried by the rotor can create a significant axial load on the rotor. This axial load is present in centrifugal pumps based on an axial flux gap motor architecture such as Wampler or Woodard. Woodard and Wampler both rely on hydrodynamic thrust bearings to overcome this axial loading force. Despite the lack of contact, hydrodynamic bearings can still damage blood cells as a result of shear forces related to the load carried by the hydrodynamic bearings.

    [0015] The repulsive radial magnetic bearing of Wampler exacerbates the axial loads created by the magnetic attraction between the drive magnets and the back iron. Although the repulsive radial magnetic bearing creates radial stability, it introduces considerable axial instability. This axial instability can contribute further to the axial loading. This additional axial loading creates greater shear forces for any axial hydrodynamic bearing that can cause undesirable hemolysis for blood applications. In addition, the power required to sustain the hydrodynamic bearing increases as the load increases. Thus highly loaded hydrodynamic bearings can impose a significant power penalty.

    [0016] The blood pump of Figure 1 includes a magnetic axial bearing that serves to reduce or offset the axial load imposed on the rotor by the interaction between the drive magnets and the back iron. The axial magnetic bearing is formed by the interaction between a spindle magnet assembly 160 disposed within the spindle and a rotor magnet assembly 180 carried by the rotor. In the illustrated embodiment, the rotor magnet assembly 180 is disposed proximate the impeller, but the magnets of the rotor magnet assembly are not located within the blades. A set screw 134 permits longitudinal adjustment of the axial position of the axial magnetic bearing by moving the spindle magnet assembly along a longitudinal axis of the spindle.

    [0017] Figure 2 illustrates one embodiment of the axial magnetic bearing. The rotor magnet assembly includes a first rotor bearing magnet 282 and a second rotor bearing magnet 284 proximately disposed to each other. The first and second rotor bearing magnets are permanent magnets. In one embodiment, a pole piece 286 is disposed between them. A pole piece or flux concentrator serves to concentrate the magnetic flux produced by rotor bearing magnets 282 and 284. In an alternative embodiment, element 286 is merely a spacer to aid in positioning the first and second bearing magnets 282, 284 and does not serve to concentrate any magnetic flux. In other embodiments, element 286 is omitted so that the rotor magnet assembly does not include a spacer or a pole piece element.

    [0018] In one embodiment, elements 282 and 284 are monolithic, ring-shaped permanent magnets. In alternative embodiments, the bearing magnets may be non-monolithic compositions. For example, a bearing magnet may be composed of a plurality of pie-shaped, arcuate segment-shaped, or other-shaped permanent magnet elements that collectively form a ring-shaped permanent magnet structure.

    [0019] The rotor axial bearing magnet assembly is distinct from the drive magnets 222 carried by a portion of the rotor other than the blades 221. In the illustrated embodiment, the drive magnets are disposed within the non-bladed portion 228 of the rotor.

    [0020] The spindle magnet assembly includes a first spindle bearing magnet 262 and a second spindle bearing magnet 264. The first and second spindle bearing magnets are permanent magnets. In one embodiment, a pole piece 266 is disposed between them. Pole piece 266 concentrates the magnetic flux produced by the spindle bearing magnets 262 and 264. In an alternative embodiment, element 266 is merely a spacer for positioning the first and second spindle bearing magnets and does not serve to concentrate any magnetic flux. In other embodiments, element 266 is omitted so that the spindle magnet assembly does not include a spacer or a pole piece element.

    [0021] In the illustrated embodiment, permanent magnets 262 and 264 are cylindrical. Other shapes may be utilized in alternative embodiments. The ring-shaped rotor magnets rotate with the impeller about a longitudinal axis of the spindle that is shared by the spindle bearing magnet assembly.

    [0022] The permanent magnets of each of the spindle and rotor bearing assemblies are arranged such that the magnetic vectors of the individual magnets on either side of the intervening pole pieces oppose each other. Each side of a given pole piece is adjacent the same pole of different magnets. Thus the magnetic vectors of magnets 262 and 264 oppose each other (e.g., N-to-N or S-to-S). Similarly, the magnetic vectors of magnets 282 and 284 oppose each other.

    [0023] The orientation of the magnets is chosen to establish an axial attraction whenever the bearings are axially misaligned. Note that the relative orientations of the spindle and rotor magnet assemblies are selected so that the spindle and rotor magnet assemblies attract each other (e.g., S-to-N, N-to-S). The magnet vector orientation selected for the magnets of one assembly determines the magnetic vector orientation for the magnets of the other assembly. Table 292 illustrates the acceptable magnetic vector combinations for the first and second rotor bearing magnets (MR1, MR2) and the first and second spindle bearing magnets (MS1, MS2). Forces such as the magnetic attraction between the back iron and drive magnets that tend to axially displace the magnet bearing assemblies are offset at least in part by the magnetic attraction between the axial bearings that provide an axial force to restore the axial position of the rotor.

    [0024] Figure 2 also illustrates wedges or tapered surfaces 272 that form a portion of a hydrodynamic bearing when the clearance between a face of the non-bladed portion of the rotor (see, e.g., bottom face 124 of Figure 1) and the back of the pump housing falls below a pre-determined threshold. In various embodiments, this pre-determined threshold is within a range of 0.0002 inches to 0.003 inches. Thus in one embodiment, the pump includes an axial hydrodynamic bearing. The surface geometry providing the axial hydrodynamic bearing may be located on the rotor or the housing.

    [0025] Although the spindle magnet assembly is intended to provide an axial magnetic bearing, the attractive force between the spindle and rotor magnet assemblies also has a radial component. This radial component may be utilized to offset radial loading of the impeller due to the pressure gradient across the impeller. The radial component also serves as a pre-load during initial rotation and a bias during normal operation to prevent eccentric rotation of the rotor about the spindle. Such an eccentric rotation can result in fluid whirl or whip which is detrimental to the pumping action. The biasing radial component helps to maintain or restore the radial position of the rotor and the pumping action, for example, when the pump is subjected to external forces as a result of movement or impact.

    [0026] Instead of a spindle magnet assembly interacting with a rotor bearing magnet assembly to form the magnetic bearing, a ferromagnetic material might be used in lieu of one of a) the spindle magnet assembly, or b) the rotor bearing magnet assembly (but not both) in alternative embodiments.

    [0027] The magnetic bearing is still composed of a spindle portion and a rotor portion, however, one of the spindle and the rotor portions utilizes ferromagnetic material while the other portion utilizes permanent magnets. The ferromagnetic material interacts with the magnets to create a magnetic attraction between the rotor and spindle. Examples of ferromagnetic materials includes iron, nickel, and cobalt.

    [0028] In one embodiment, the ferromagnetic material is "soft iron". Soft iron is characterized in part by a very low coercivity. Thus irrespective of its remanence or retentivity, soft iron is readily magnetized (or re-magnetized) in the presence of an external magnetic field such as those provided by the permanent magnets of the magnetic bearing system.

    [0029] Figure 3 illustrates various locations for the placement of the spindle portion of the magnetic bearing. In one embodiment, the spindle magnet assembly 360 is axially aligned with a longitudinal axis 390 of the spindle so that the spindle and spindle magnet assembly share the same central longitudinal axis. In an alternative embodiment, the spindle magnet assembly is radially offset so that the spindle and spindle magnet assembly do not share the same central axis. In particular, the longitudinal axis 362 of the spindle magnet assembly 360 is displaced from the longitudinal axis 390 of the spindle. This latter positioning may be desirable to provide some radial biasing force. A difference in pressure across the impeller tends to push the impeller radially towards one side of the pump housing. This radial load may be offset at least in part by offsetting the spindle magnet assembly.

    [0030] Although the spindle and rotor magnet assemblies are illustrated as comprising 2 magnetic elements each, the magnet assemblies may each comprise a single magnet instead. A greater spring rate may be achieved with multiple magnetic elements per assembly configured as illustrated instead of a single magnet per assembly. The use of two magnetic elements per assembly results in a bearing that tends to correct bi-directional axial displacements from a position of stability (i.e., displacements above and below the point of stability) with a greater spring rate than single magnetic elements per assembly.

    [0031] The magnetic force generated by the axial magnetic bearing will exhibit a radial component in addition to their axial components. The radial component will tend to de-stabilize the impeller. In particular, the radial component may introduce radial position instability for the magnetic bearing of either Figures 1 or 2.

    [0032] This radial instability may be overcome using radial hydrodynamic bearings. Referring to Figure 1, the pump may be designed for a radial hydrodynamic bearing (i.e., hydrodynamic journal bearing) located between the spindle 130 and the rotor along the bore of the rotor. The clearances illustrated in Figure 1 are exaggerated. Hydrodynamic journal bearings require narrow clearances to be effective. In various embodiments, the hydrodynamic journal bearing clearances range from 0.0005 - 0.020 inches. The surface geometries suitable for axial (thrust) or radial (journal) hydrodynamic bearings may be located on either the rotor or on an associated portion of the housing (or spindle). In one embodiment, the surface geometry includes features such as one or more pads (i.e., a feature creating an abrupt change in clearance such as a step of uniform height). In alternative embodiments, the surface geometry includes features such as one or more tapers.

    [0033] Figure 4 illustrates one embodiment of the rotor 400 including an impeller. The impeller includes a plurality of blades 420 used for pumping the working fluid such as blood. The rotor includes a bore 410. The rotor bore is coaxially aligned with the longitudinal axis of the spindle within the pump housing. Drive magnets (not illustrated) are disposed within the non-bladed portion 430 of the rotor (i.e., within the rotor but not within any blades of the impeller portion of the rotor). The motor rotor and pump impeller are thus integrated so that a drive shaft is not required. Elimination of the drive shaft also permits elimination of shaft seals for the pump.

    [0034] In one embodiment, the rotor has a grooved bore. In particular, the bore has one or more helical grooves 450. The bore grooves have a non-zero axial pitch. The groove is in fluid communication with the working fluid of the pump during operation of the pump.

    [0035] Figure 5 illustrates the pump 510 operationally coupled to move a working fluid 540 from a source 520 to a destination 530. A first working fluid conduit 522 couples the source to the pump inlet 514. A second working fluid conduit 532 couples the pump outlet 516 to the destination. The working fluid is the fluid moved by the pump from the source to the destination. In a medical application, for example, the working fluid might be blood. In one embodiment, the source and destination are arteries such that the pump moves blood from one artery to another artery.

    [0036] Various "contactless" bearing mechanisms have been described as alternatives to mechanical contact bearings for rotary pumps. In particular, rotor, impeller, and housing design features are provided to achieve hydrodynamic or magnetic bearings. These design features may be used in conjunction with each other, if desired.

    [0037] In the preceding detailed description, the invention is described with reference to specific exemplary embodiments thereof. Various modifications and changes may be made thereto without departing from the scope of the invention as set forth in the claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.


    Claims

    1. A centrifugal pump apparatus adapted to pump a liquid, and comprising:

    a pump housing (110) defining a pumping chamber (112), the pump housing having a spindle (130) extending into the pumping chamber and defining a longitudinal axis;

    a rotor (120) configured to rotate about the spindle, the rotor including an impeller comprising at least one blade;

    drive magnets (122) disposed in said rotor and a back iron (150) and drive windings (140) disposed in said pump housing;

    a passive axial magnetic bearing disposed in said pump apparatus reducing an axial load imposed on said rotor by interaction between said drive magnets and said back iron;

    a rotor portion of said passive axial magnetic bearing disposed within a non-bladed portion of the rotor;

    and a spindle portion of said passive axial magnetic bearing disposed within the spindle,

    wherein the spindle and rotor portions of the passive axial magnetic bearing are configured to attract each other,

    wherein at least one of the rotor and spindle portions of the magnetic bearing comprises a first and a second magnet,

    wherein the first and second magnets are arranged proximate each other with their respective magnetic vectors parallel to said longitudinal axis; wherein at least one of the pump housing, the spindle and the rotor has surface geometry suitable for supporting at least one hydrodynamic bearing; and wherein said passive axial magnetic bearing and said at least one hydrodynamic bearing constitute the sole bearings for levitating said rotor during rotation of said rotor.


     
    2. The apparatus of claim 1, wherein the spindle portion of the passive axial magnet bearing comprises first and second magnets (262, 264) arranged proximate each other with their respective magnetic vectors opposing each other.
     
    3. The apparatus of claim 1, wherein the rotor portion of the passive axial magnetic bearing comprises first and second magnets (282, 284) arranged proximate each other with their respective magnetic vectors opposing each other.
     
    4. The apparatus of claim 1, wherein said hydrodynamic bearing is comprised of a surface geometry (172) disposed on said pump housing and structured to generate a hydrodynamic bearing for at least partially supporting the rotor during rotation.
     
    5. The apparatus of claim 3, wherein said spindle portion of the passive axial magnetic bearing comprises at least one magnet and a longitudinal axis (362) of said at least one magnet being displaced from a longitudinal axis (390) of the spindle.
     
    6. The apparatus of claim 1, wherein said rotor has at least one grooved bore (416).
     
    7. The apparatus of claim 1, wherein a plurality of drive magnets are carried by a nonbladed portion of the rotor; wherein the drive magnets cooperate with the drive windings to rotate the rotor.
     
    8. The apparatus of claim 1, wherein the first and second magnets have one of a cylindrical and a ring-shaped form factor.
     
    9. The apparatus of claim 3, wherein the first and second magnets are concentrically aligned about said rotor.
     
    10. The apparatus of claim 4, wherein said at least one hydrodynamic bearing includes a radial hydrodynamic bearing between said spindle and a bore of said rotor.
     
    11. The apparatus of claim 10, wherein said surface geometry of said spindle and said bore of said rotor is comprised of a narrow clearance therebetween.
     
    12. The apparatus of claim 4, wherein said at least one hydrodynamic bearing includes an axial hydrodynamic bearing between said rotor and said pump housing.
     
    13. The apparatus of claim 12, wherein said surface geometry of said pump housing comprises at least one tapered surface facing a bottom surface of said rotor.
     
    14. The apparatus of claim 1, wherein said rotor has a plurality of helical grooves (450) disposed in a bore of said rotor.
     
    15. A method of pumping a fluid comprising:

    providing a centrifugal pump according to claim 1;

    rotating said rotor so as to transfer fluid via an impeller from an inlet to an outlet of said pump housing;

    exerting an attractive magnetic force between said pump housing and said rotor so as to create an axial restoration force that opposes said axial load caused by said rotation and that stabilizes an axial position of said rotor in said pump housing during said rotating

    exerting a further opposing force against said axial load through the creating of an axial hydrodynamic bearing force on said rotor from said axial hydrodynamic bearing.


     
    16. A method according to claim 15, wherein the exerting of an attractive magnetic force includes creating an axial magnetic bearing by moving said at least one housing magnet along a longitudinal axis of said pump housing relative to said at least one corresponding rotor magnet.
     
    17. A method according to claim16, wherein the exerting of an attractive magnetic force includes positioning said at least one housing magnet in an axially upward direction with respect to said at least one corresponding rotor magnet when said rotor is at rest.
     
    18. A method according to claim 15, wherein the creating of an axial magnetic bearing includes positioning two housing magnets axially along said pump housing.
     
    19. A method according to claim 18, wherein the creating of an axial magnetic bearing further includes positioning two rotor magnets axially along said rotor, wherein the poles of one rotor magnet are opposed to the poles of the other rotor magnet.
     
    20. A method according to claim 15, wherein the creating of an axial magnetic bearing includes positioning at least one housing magnet such that a longitudinal axis of said at least one housing magnet is axially offset from a longitudinal axis of said at least one rotor magnet.
     
    21. A method according to claim 19, wherein the poles of one housing magnet are opposed to the poles of the other housing magnet.
     


    Ansprüche

    1. Zentrifugalpumpenvorrichtung, die zum Fördern einer Flüssigkeit ausgeführt ist und Folgendes aufweist:

    ein Pumpengehäuse (110), das eine Pumpkammer (112) definiert, wobei das Pumpengehäuse eine Spindel (130) hat, die sich in die Pumpkammer erstreckt und eine Längsachse definiert;

    einen Rotor (120), der zum Drehen um die Spindel gestaltet ist, wobei der Rotor ein Laufrad hat, das wenigstens eine Schaufel aufweist;

    Antriebsmagnete (122), die in dem genannten Rotor positioniert sind, und einen Eisenrückschluss (150) und Antriebswicklungen (140), die in dem genannten Pumpengehäuse positioniert sind;

    ein passives axiales magnetisches Lager, in der genannten Pumpenvorrichtung positioniert, das eine auf den genannten Rotor aufgebrachte axiale Beanspruchung durch Wechselwirkung zwischen den genannten Antriebsmagneten und dem genannten Eisenrückschluss reduziert;

    einen Rotorteil des genannten passiven axialen magnetischen Lagers, der in einem schaufellosen Teil des Rotors positioniert ist;

    und einen Spindelteil des genannten passiven axialen magnetischen Lagers, der in der Spindel positioniert ist,

    wobei der Spindel- und der Rotorteil des passiven axialen magnetischen Lagers so ausgebildet sind, dass sie einander anziehen,

    wobei wenigstens einer von dem Rotor- und dem Spindelteil des magnetischen Lagers einen ersten und einen zweiten Magneten aufweist,

    wobei der erste und der zweite Magnet nahe aneinander angeordnet sind, wobei ihre jeweiligen magnetischen Vektoren parallel zu der genannten Längsachse sind; wobei wenigstens eins von dem Pumpengehäuse, der Spindel und dem Rotor eine Oberflächengeometrie hat, die zum Unterstützen von wenigstens einem hydrodynamischen Lager geeignet ist; und wobei das genannte passive axiale magnetische Lager und das genannte wenigstens eine hydrodynamische Lager die einzigen Lager zum Schwebenlassen des genannten Rotors während der Drehung des genannten Rotors bilden.


     
    2. Vorrichtung nach Anspruch 1, wobei der Spindelteil des passiven axialen Magnetlagers einen ersten und einen zweiten Magneten (262, 264) aufweist, die nahe aneinander angeordnet sind, wobei ihre jeweiligen magnetischen Vektoren einander entgegengesetzt sind.
     
    3. Vorrichtung nach Anspruch 1, wobei der Rotorteil des passiven axialen magnetischen Lagers einen ersten und einen zweiten Magneten (282, 284) aufweist, die nahe aneinander angeordnet sind, wobei ihre jeweiligen magnetischen Vektoren einander entgegengesetzt sind.
     
    4. Vorrichtung nach Anspruch 1, wobei das genannte hydrodynamische Lager eine Oberflächengeometrie (172) umfasst, die an dem genannten Pumpengehäuse positioniert ist und zum Erzeugen eines hydrodynamischen Lagers zum wenigstens teilweisen Unterstützen des Rotors während der Drehung aufgebaut ist.
     
    5. Vorrichtung nach Anspruch 3, wobei der genannte Spindelteil des passiven axialen magnetischen Lagers wenigstens einen Magneten aufweist und eine Längsachse (362) des genannten wenigstens einen Magneten von einer Längsachse (390) der Spindel verschoben ist.
     
    6. Vorrichtung nach Anspruch 1, wobei der genannte Rotor wenigstens eine genutete Bohrung (416) hat.
     
    7. Vorrichtung nach Anspruch 1, wobei mehrere Antriebsmagnete von einem schaufellosen Teil des Rotors getragen werden; wobei die Antriebsmagnete mit den Antriebswicklungen zum Drehen des Rotors zusammenarbeiten.
     
    8. Vorrichtung nach Anspruch 1, wobei der erste und der zweite Magnet einen von einem zylinderförmigen und einem ringförmigen Formfaktor haben.
     
    9. Vorrichtung nach Anspruch 3, wobei der erste und der zweite Magnet konzentrisch um den genannten Rotor ausgerichtet sind.
     
    10. Vorrichtung nach Anspruch 4, wobei das genannte wenigstens eine hydrodynamische Lager ein radiales hydrodynamisches Lager zwischen der genannten Spindel und einer Bohrung des genannten Rotors beinhaltet.
     
    11. Vorrichtung nach Anspruch 10, wobei die genannte Oberflächengeometrie der genannten Spindel und der genannten Bohrung des genannten Rotors einen schmalen Zwischenraum dazwischen umfasst.
     
    12. Vorrichtung nach Anspruch 4, wobei das genannte wenigstens eine hydrodynamische Lager ein axiales hydrodynamisches Lager zwischen dem genannten Rotor und dem genannten Pumpengehäuse beinhaltet.
     
    13. Vorrichtung nach Anspruch 12, wobei die genannte Oberflächengeometrie des genannten Pumpengehäuses wenigstens eine Schrägfläche aufweist, die einer Unterseite des genannten Rotors zugekehrt ist.
     
    14. Vorrichtung nach Anspruch 1, wobei der genannte Rotor mehrere Spiralnuten (450) hat, die in einer Bohrung des genannten Rotors positioniert sind.
     
    15. Verfahren zum Fördern eines Fluids, das Folgendes aufweist:

    Bereitstellen einer Zentrifugalpumpe nach Anspruch 1;

    Drehen des genannten Rotors, um Fluid über ein Laufrad von einem Einlass zu einem Auslass des genannten Pumpengehäuses zu transportieren;

    Ausüben einer anziehenden Magnetkraft zwischen dem genannten Pumpengehäuse und dem genannten Rotor, um eine axiale Rückstellkraft herzustellen, die der genannten axialen Beanspruchung entgegengesetzt ist, die durch die genannte Drehung verursacht wird, und die eine axiale Position des genannten Rotors in dem genannten Pumpengehäuse während des genannten Drehens stabilisiert;

    Ausüben einer weiteren Gegenkraft gegen die genannte axiale Beanspruchung durch das Herstellen einer axialen hydrodynamischen Lagerkraft auf den genannten Rotor von dem genannten axialen hydrodynamischen Lager.


     
    16. Verfahren nach Anspruch 15, wobei das Ausüben einer anziehenden Magnetkraft das Herstellen eines axialen magnetischen Lagers durch Bewegen des genannten wenigstens einen Gehäusemagnets an einer Längsachse des genannten Pumpengehäuses entlang relativ zu dem genannten wenigstens einen entsprechenden Rotormagneten beinhaltet.
     
    17. Verfahren nach Anspruch 16, wobei das Ausüben einer anziehenden Magnetkraft das Positionieren des genannten wenigstens einen Gehäusemagneten in einer axialen Aufwärtsrichtung in Bezug auf den genannten wenigstens einen entsprechenden Rotormagneten, wenn der genannte Rotor ruht, beinhaltet.
     
    18. Verfahren nach Anspruch 15, wobei das Herstellen eines axialen magnetischen Lagers das Positionieren von zwei Gehäusemagneten axial an dem genannten Pumpengehäuse entlang beinhaltet.
     
    19. Verfahren nach Anspruch 18, wobei das Herstellen eines axialen magnetischen Lagers ferner das Positionieren von zwei Rotormagneten axial an dem genannten Rotor entlang beinhaltet, wobei die Pole von einem Rotormagneten den Polen des anderen Rotormagneten entgegengesetzt sind.
     
    20. Verfahren nach Anspruch 15, wobei das Herstellen eines axialen magnetischen Lagers das Positionieren von wenigstens einem Gehäusemagneten beinhaltet, so dass eine Längsachse des genannten wenigstens einen Gehäusemagneten axial von einer Längsachse des genannten wenigstens einen Rotormagneten versetzt ist.
     
    21. Verfahren nach Anspruch 19, wobei die Pole von einem Gehäusemagneten den Polen des anderen Gehäusemagneten entgegengesetzt sind.
     


    Revendications

    1. Appareil de pompe centrifuge adapté de façon à pomper un liquide et comprenant :

    un corps de pompe (110) définissant une chambre de pompage (112), ce corps de pompe ayant une broche (130) s'étendant dans la chambre de pompage et définissant un axe longitudinal ;

    un rotor (120) configuré de façon à tourner autour de la broche, ce rotor comprenant une roue comportant au moins une aube ;

    des aimants d'entraînement (122) disposés dans ledit rotor et une culasse magnétique (150) et des enroulements d'entraînement (140) disposés dans ledit corps de pompe ;

    un palier magnétique axial passif disposé dans ledit appareil de pompe réduisant une charge axiale imposée sur ledit rotor par l'interaction entre lesdits aimants d'entraînement et ladite culasse magnétique ;

    une partie rotor dudit palier magnétique axial passif disposée à l'intérieur d'une partie sans aubes du rotor ;

    et une partie broche dudit palier magnétique axial passif disposée à l'intérieur de la broche,

    les parties broche et rotor du palier magnétique axial passif étant configurées de façon à s'attirer l'une l'autre,

    au moins soit la partie rotor, soit la partie broche du palier magnétique axial passif comportant un premier et un deuxième aimant,

    ce premier et de deuxième aimant étant disposés à proximité l'un de l'autre avec leurs vecteurs magnétiques respectifs parallèles audit axe longitudinal ; au moins soit le corps de pompe, soit la broche, soit le rotor ayant une géométrie de surface appropriée pour supporter au moins un palier hydrodynamique ; et ledit palier magnétique axial passif et ledit au moins palier hydrodynamique constituant les paliers uniques pour faire léviter ledit rotor pendant la rotation dudit rotor.


     
    2. Appareil selon la revendication 1, dans lequel la partie broche du palier magnétique axial passif comporte un premier et un deuxième aimant (262, 264) disposés à proximité l'un de l'autre avec leurs vecteurs magnétiques respectifs s'opposant l'un à l'autre.
     
    3. Appareil selon la revendication 1, dans lequel la partie rotor du palier magnétique axial passif comporte un premier et un deuxième aimant (282, 284) disposés à proximité l'un de l'autre avec leurs vecteurs magnétiques respectifs s'opposant l'un à l'autre.
     
    4. Appareil selon la revendication 1, dans lequel ledit palier hydrodynamique est constitué d'une géométrie de surface (172) disposée sur ledit corps de pompe et structurée de façon à produire un palier hydrodynamique pour supporter le rotor au moins partiellement pendant la rotation.
     
    5. Appareil selon la revendication 3, dans lequel ladite partie broche du palier magnétique axial passif comporte au moins un aimant et un axe longitudinal (362) dudit au moins un aimant étant déplacé par rapport à un axe longitudinal (390) de la broche.
     
    6. Appareil selon la revendication 1, dans lequel ledit rotor a au moins un alésage creusé d'une gorge (416).
     
    7. Appareil selon la revendication 1, dans lequel une pluralité d'aimants d'entraînement sont portés par une partie sans aubes du rotor ; ces aimants d'entraînement coopérant avec les enroulements d'entraînement pour faire tourner le rotor.
     
    8. Appareil selon la revendication 1, dans lequel le premier et le deuxième aimant ont un facteur de forme soit cylindrique, soit annulaire.
     
    9. Appareil selon la revendication 3, dans lequel le premier et le deuxième aimant sont alignés concentriquement autour dudit rotor.
     
    10. Appareil selon la revendication 4, dans lequel ledit au moins un palier hydrodynamique comprend un palier hydrodynamique radial entre ladite broche et un alésage dudit rotor.
     
    11. Appareil selon la revendication 10, dans lequel ladite géométrie de surface de ladite broche et dudit alésage dudit rotor est constituée d'un jeu étroit entre eux.
     
    12. Appareil selon la revendication 4, dans lequel ledit au moins un palier hydrodynamique comprend un palier hydrodynamique axial entre ledit rotor et ledit corps de pompe.
     
    13. Appareil selon la revendication 12, dans lequel ladite géométrie de surface dudit corps de pompe consiste en au moins une surface tronconique faisant face à une surface inférieure dudit rotor.
     
    14. Appareil selon la revendication 1, dans lequel ledit rotor a une pluralité de gorges hélicoïdales (450) disposées dans un alésage dudit rotor.
     
    15. Procédé de pompage d'un fluide comprenant :

    la fourniture d'une pompe centrifuge selon la revendication 1 ;

    la rotation dudit rotor de façon à transférer le fluide via une roue d'une entrée à une sortie dudit corps de pompe ;

    le déploiement d'une force d'attraction magnétique entre ledit corps de pompe et ledit rotor de façon à créer une force de restauration axiale qui s'oppose à ladite charge axiale causée par ladite rotation et qui stabilise une position axiale dudit rotor dans ledit corps de pompe pendant ladite rotation,

    le déploiement d'une autre force d'opposition contre ladite charge axiale au moyen de la création d'une force de palier hydrodynamique axial sur ledit rotor venant dudit palier hydrodynamique axial.


     
    16. Procédé selon la revendication 15, dans lequel le déploiement d'une force d'attraction magnétique comprend la création d'un palier magnétique axial en bougeant ledit au moins un aimant de corps le long d'un axe longitudinal dudit corps de pompe par rapport audit au moins un aimant de rotor correspondant.
     
    17. Procédé selon la revendication 16, dans lequel le déploiement d'une force d'attraction magnétique comprend le positionnement dudit au moins aimant de corps dans une direction axialement vers le haut par rapport audit au moins un aimant de rotor correspondant lorsque ledit rotor est au repos.
     
    18. Procédé selon la revendication 15, dans lequel la création d'un palier magnétique axial comprend le positionnement de deux aimants de corps axialement le long dudit corps de pompe.
     
    19. Procédé selon la revendication 18, dans lequel la création d'un palier magnétique axial comprend en outre le positionnement de deux aimants de rotor axialement le long dudit rotor, les pôles d'un aimant de rotor étant opposés aux pôles de l'autre aimant de rotor.
     
    20. Procédé selon la revendication 15, dans lequel la création d'un palier magnétique axial comprend le positionnement d'au moins un aimant de corps de manière à ce qu'un axe longitudinal dudit au moins un aimant de corps soit décalé axialement d'un axe longitudinal dudit au moins aimant de rotor.
     
    21. Procédé selon la revendication 19, dans lequel les pôles d'un aimant de corps sont opposés aux pôles de l'autre aimant de corps.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description