(19)
(11)EP 2 699 368 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
16.02.2022 Bulletin 2022/07

(21)Application number: 12721032.6

(22)Date of filing:  18.04.2012
(51)International Patent Classification (IPC): 
B22D 23/00(2006.01)
B22D 17/02(2006.01)
F04D 7/06(2006.01)
B22D 39/02(2006.01)
F04D 29/047(2006.01)
(52)Cooperative Patent Classification (CPC):
B22D 23/00; B22D 39/02; B22D 17/02; F04D 7/065; F04D 29/0473
(86)International application number:
PCT/US2012/034048
(87)International publication number:
WO 2012/145381 (26.10.2012 Gazette  2012/43)

(54)

MOLD PUMP ASSEMBLY

FORMPUMPENANORDNUNG

ENSEMBLE POMPE DE MOULE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 18.04.2011 US 201161476433 P

(43)Date of publication of application:
26.02.2014 Bulletin 2014/09

(73)Proprietor: Pyrotek Inc.
Solon, OH 44139 (US)

(72)Inventor:
  • TIPTON, Jon
    Aurora, OH 44202 (US)

(74)Representative: Held, Stephan et al
Meissner Bolte Patentanwälte Rechtsanwälte Partnerschaft mbB Widenmayerstraße 47
80538 München
80538 München (DE)


(56)References cited: : 
EP-A1- 1 229 250
US-A- 5 685 701
US-A1- 2010 266 396
US-A- 4 475 866
US-A- 5 716 195
  
      
    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

    BACKGROUND



    [0001] The present embodiment relates to a pump assembly to pump molten metal. It finds particular application in conjunction with a shaft and impeller assembly for variable pressure pumps for filling molds with molten metal, and will be described with particular reference thereto.

    [0002] At times it is necessary to move metals in their liquid or molten form. Molten metal pumps are utilized to transfer or recirculate molten metal through a system of pipes or within a storage vessel. These pumps generally include a motor supported by a base member having a rotatable elongated shaft extending into a body of molten metal to rotate an impeller. The base member is submerged in the molten metal and includes a housing or pump chamber having the impeller located therein. The motor is supported by a platform that is rigidly attached to a plurality of structural posts or a central support tube that is attached to the base member. The plurality of structural posts and the rotatable elongated shaft extends from the motor and into the pump chamber submerged in the molten metal within which the impeller is rotated. Rotation of the impeller therein causes a directed flow of molten metal.

    [0003] The impeller is mounted within the chamber in the base member and is supported by bearing rings to act as a wear resistant surface and allow smooth rotation therein. Additionally, a radial bearing surface can be provided an the elongated shaft or impeller to prevent excessive vibration of the pump assembly which could lead to inefficiency or even failure of pump components. These pumps have traditionally been referred to as centrifugal pumps.

    [0004] Although centrifugal pumps operate satisfactorily to pump molten metal, they have never found acceptance as a means to fill molten metal molds. Rather, this task has been left to electromagnetic pumps, pressurized furnaces and ladeling. Known centrifugal pumps generally control a flow rate and pressure of molten metal by modulating the rotational rate of the impeller. However, this control mechanism experiences erratic control of the flow rate and pressure of molten metal when attempting to transfer molten metal into a mold such as a form mold. The erratic control of the flow of molten metal into the form mold is especially prevalent when attempting to fill a form mold for a complicated or intricately formed tool or part. US 4 457 866 A is directed to a primary loop pump installed in the hot leg of a sodium-cooled fast breeder reactor. The system described, is a closed system for cooling a fast breeder reactor wherein neither delivery nozzle or overflow nozzle lead to an external environment. US 2010/0266396 A1 discloses a transfer pump for pumping molten metal having a riser with a reusable socket. The pump is able to lift the impeller to achieve multiple transfer or discharge functions. When the impeller is raised to direct molten metal from a upper pumping chamber to a riser, the device shown in US 2010/0266396 A1 uses bearing ring pairs that seal both the top and bottom edges of an active pumping chamber.

    BRIEF DESCRIPTION



    [0005] In one embodiment, the present disclosure relates to a molten metal pump assembly to fill molds with molten metal comprised of aluminum. The pump assembly comprises an elongated shaft connecting a motor to an impeller. The impeller is housed within a pump chamber of a base member such that rotation of the impeller draws molten metal into the chamber at an inlet and forces molten metal through an outlet of the chamber. The impeller includes a first radial edge spaced from a second radial edge such that the first radial edge is adjacent the elongated shaft. A bearing assembly surrounds the impeller within the chamber, the bearing assembly includes a first bearing adapted to support the rotation of the impeller at the first radial edge and a second bearing adapted to support the rotation of the impeller at the second radial edge. At least one bypass gap to a surrounding environment is interposed between one of the first and second bearings and the associated first and second radial edges. The bypass gap comprises a width between the second bearing ring and the associated second radial edge of the impeller which is at least about 1.25 x greater in width than a lubrication gap between the first bearing ring and the first radial edge of the impeller. The bypass gap is operative to manipulate a flow rate and a head pressure of the molten

    [0006] metal. Molten metal leaks from the chamber through the bypass gap at a predetermined rate as the impeller is rotated such that a precise control of the flow rate is achieved.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0007] 

    FIGURE 1 is a front view of a prior art molten metal pump assembly;

    FIGURE 2 is a cross sectional view of a portion of the molten metal pump assembly, the portion including an elongated shaft attached to an impeller within a chamber of a base member;

    FIGURE 3 is a perspective view of the elongated shaft and the impeller;

    FIGURE 4 is an end view of the impeller;

    FIGURE 5 is a front view of the elongated shaft;

    FIGURE 6 is a cross sectional view of the base member;

    FIGURE 7 is an exploded cross sectional view of the elongated shaft attached to the impeller within the chamber of the base member illustrated in FIGURE 2;

    FIGURE 8 is a graph being not a part of the claimed invention indicating the relationship between molten metal pressure at an outlet and a molten metal flow rate relative to the rotations per minute (RPM) of the impeller of the pump assembly;

    FIGURE 9 is a graph being not a part of the claimed invention indicating an exemplary relationship between RPM and time related to a programmable mold fill profile;

    FIGURE 10 is a graph of an exemplary programmable mold fill profile associated with a complicated mold, which is not a part of the claimed invention.


    DETAILED DESCRIPTION



    [0008] It will be appreciated that the drawings are not to scale and that portions of certain elements may be exaggerated for the purpose of clarity and ease of illustration.

    [0009] With reference to FIGURE 1, an example of a molten metal pump assembly 10 submerged in a bath of molten metal 12 is displayed. The molten metal 12, such as aluminum, can be located within a furnace or tank (not shown). The molten metal pump assembly 10 includes a motor 14 connected to an elongated shaft 16 via coupling 17. The motor is adapted to be run at variable speed by a programmable controller 19, such as a computer or other processor. The elongated shaft 16 is connected to an impeller 22 located in the chamber 18 of a base member 20. The base member 20 is suspended by a plurality of refractory posts 24 attached to a motor mount 26. An alternative form of post could also be employed wherein a steel rod surrounded by a refractory sheath extends between the motor mount and the base member 20.

    [0010] The elongated shaft 16 is rotated by the motor 14 and extends from the motor 14 and into the pump chamber 18 submerged in the molten metal 12 within which the impeller 22 is rotated. Rotation of the impeller 22 therein causes a directed flow of molten metal 12 through an associated metal delivery conduit (not shown) such as a riser, adapted for fluid metal flow. The riser for the metal delivery conduit system is connected to the outlet of the pump chamber 18 which is typically adjacent a side wall or top wall of the base member. These types of pumps are often referred to as transfer pumps. An example of one suitable transfer pump is shown in U.S. Patent 5,947,705, the disclosure of which is herein incorporated by reference.

    [0011] With reference to FIGURES 2-6, elements of the molten metal pump assembly 10 of the present disclosure are illustrated. More particularly, the elongated shaft 16 has a cylindrical shape having a rotational axis that is generally perpendicular to the base member 20. The elongated shaft has a proximal end 28 that is adapted to attach to the motor 14 by the coupling 17 and a distal end 30 that is connected to the impeller 22. The impeller 22 is rotably positioned within the pump chamber 18 such that operation of the motor 14 rotates the elongated shaft 16 which rotates the impeller 22 within the pump chamber 18.

    [0012] The base member 20 defines the pump chamber 18 that receives the impeller 22. The base member 20 is configured to structurally receive the refractory posts 24 (optionally comprised of an elongated metal rod within a protective refractory sheath) within passages 31. Each passage 31 is adapted to receive the metal rod component of the refractory post 24 to rigidly attach to a motor mount 26. The motor mount 26 supports the motor 14 above the molten metal 12.

    [0013] In one example, the impeller 22 is configured with a first radial edge 32 that is axially spaced from a second radial edge 34. The first and second radial edges 32, 34 are located peripherally about the circumference of the impeller 22. The pump chamber 18 includes a bearing assembly 35 having a first bearing ring 36 axially spaced from a second bearing ring 38. The first radial edge 32 is facially aligned with the first bearing ring 36 and the second radial edge 34 is facially aligned with the second bearing ring 38. The bearing rings are made of a material, such as silicon carbide, having frictional bearing properties at high temperatures to prevent cyclic failure due to high frictional forces. The bearings are adapted to support the rotation of the impeller 22 within the base member such that the pump assembly 10 is at least substantially prevented from vibrating. The radial edges of the impeller may similarly be comprised of a material such as silicon carbide. For example, the radial edges of the impeller 22 may be comprised of a silicon carbide bearing ring.

    [0014] In one example, the impeller 22 includes a first peripheral circumference 42 axially spaced from a second peripheral circumference 44. The elongated shaft 16 is attached to the impeller 22 at the first peripheral circumference 42. The second peripheral circumference 44 is spaced opposite from the first peripheral circumference 44 and aligned with a bottom portion 46 of the base member 20. The first radial edge 32 is adjacent to the first peripheral circumference 42 and the second radial edge 34 is adjacent to the second peripheral circumference 44.

    [0015] In one example, a bottom inlet 48 is provided in the second peripheral circumference 44. More particularly, the inlet comprises the annulus of a bird cage style of impeller 22. Of course, the inlet can be formed of vanes, bores, annulus ("bird cage") or other assemblies known in the art. It is noted that a top feed pump assembly or a combination top and bottom feed pump assembly may also be used.

    [0016] As will be apparent from the following discussion, a bored or bird cage impeller may be advantageous because they include a defined radial edge allowing a designed tolerance (or bypass gap) to be created with the pump chamber 18. An example of a bored impeller is provided by U.S. Patent 6,464,458, the disclosure of which is herein incorporated by reference.

    [0017] The rotation of the impeller 22 draws molten metal 12 into the inlet 48 and into the chamber 18 such that continued rotation of the impeller 22 causes molten metal 12 to be forced out of the pump chamber 18 to an outlet 50 of the base member 20.

    [0018] With reference to FIGURE 6, the bearing assembly 35 includes a base ring bearing adapter 52 that is configured to connect the second bearing ring 38 to the bottom portion 46 of the base member 20. The base ring bearing adapter 52 includes a radial flange portion 54 that is rigidly attached to a disk body 56 and is operative to support bearing rings of various sizes along the bottom portion 46 of the base member 20. The radial flange portion 54 is adjacent the pump chamber 18 and is generally perpendicular to the disk body 56.

    [0019] FIGURE 7 illustrates the impeller 22 located within the base member 20. A close tolerance is maintained between radial edge 32 of the impeller 22 and the first bearing ring 36 to provide rotational and structural support to the impeller 22 within the chamber 18. The base ring bearing adapter 52 is generally circular and is configured for receiving the second bearing ring 38. Base ring bearing adapter 52 and bearing rings of different sizes can be provided at the base member to interact with the impeller 22 such that a bypass gap 60 of a desired size is provided between the bearing ring 38 and the radial edge 34 of impeller 22. Optionally, it is contemplated that the bypass gap 60 may be provided between the first radial edge 32 and the first bearing ring 36.

    [0020] In one example, the bypass gap 60 is interposed between a portion of the second bearing ring 38 and the second radial edge 34. For example, the bypass gap 60 is a radial space interposed between at least a portion of the second bearing 38 and the second radial edge 34 of the impeller 22. The radial space is of a designed tolerance that can be varied to allow for a predetermined leakage rate of the molten metal 12.

    [0021] In this regard, it is noted that a lubrication gap 62 exists between the radial edge 32 of the impeller 22 and the bearing ring 36 disposed within the base 20. The lubrication gap 62 is a space provided within which molten metal is retained to provide a low friction boundary. The lubrication gap 62 can vary based upon the constituents of the relevant alloy. The bypass gap has a width (i.e. a distance between the impeller and the base) of at least about 1.25x the lubrication gap.

    [0022] It is also noted that a discontinuous gap width may be employed wherein relatively close tolerance regions are interspersed with relatively large bypass gap width regions.

    [0023] For example, the bypass gap 60 may be a plurality of removable segmented teeth or posts that are radially positioned about the perimeter of the impeller 22 such that a plurality of teeth maintain contact with bearing ring 38 during rotation of the impeller 22 while radial spaces interposed between the teeth are configured to allow leakage of the molten metal 12 at a predetermined rate. In another example, the bypass gap 60 may be provided by a plurality of apertures located through the first peripheral circumference 42 of the impeller to 22 allow fluid communication with the chamber 18 and an environment outside the base member. Further, it is contemplated that at least one bypass gap can also be provided downstream of the impeller 22 within the pump chamber 18 adjacent to outlet 50 or can even be located within the riser. This type of bypass gap can be comprised of a hole(s) drilled into a pump assembly component. In short, it is feasible to provide a molten metal pump that is functional in filling complex molds by providing a designed leakage path at any point in the pump assembly.

    [0024] The bypass gap 60 is operative to manipulate a flow rate and a head pressure of the molten metal 12. The bypass gap 60 allows molten metal to leak from the pump chamber 18 to an environment outside of the base member 20 at a predetermined rate. The leakage of molten metal 12 from the pump chamber 18 during the Operation of the pump assembly 10 allows an associated user to finely tune the flow rate or volumetric amount of molten metal 12 provided to an associated mold. The leakage rate of molten metal 12 through the bypass gap 60 improves the controllability of the transport of molten metal 12 and is at least in part, due to a viscosity coefficient of the molten metal 12. Namely, in one example, as the viscosity of the molten metal 12 decreases, a size of the bypass gap 60 would also be decreased to get the optimal leakage rate of molten metal 12.

    [0025] In one example, the bypass gap 60 is provided by the second bearing ring 38 such that the second bearing ring 38 includes a larger inner diameter than the first bearing ring 36 in the bearing assembly 35. In this regard, there is a greater space between said radial edge 34 and second bearing ring 38. In another example, the bypass gap 60 is provided by the impeller 22 such that the second radial edge 34 of the impeller 22 has a smaller diameter than the first radial edge 32. Here, the first radial edge 32 is abuttingly positioned and rotably supported at the first bearing ring 36 within the pump chamber 18 to form the relatively narrower lubrication gap while a bypass gap exists between the second bearing ring 38 and the second radial edge 34. Of course, a top side gap can be created by reversing the dimensions disclosed above.

    [0026] In one example, the pump assembly includes an ability to statically position molten metal 12 pumped through the outlet 50 and into a riser at approximately 1.5 feet of head pressure above a body of molten metal 12. In one example the impeller rotates approximately 850-1000 rotations per minute such that molten metal is statically held at approximately 1.5 feet above the body of molten metal 12. The bypass gap 60 manipulates the volumetric flow rate and head pressure relationship of the pump 10 such that an increased amount of rotations per minute of the impeller 22 would allow the reduction of head pressure as the flow rate of molten metal 12 is increased. This relationship schematically illustrated by the graph in FIGURE 8.

    [0027] Precise control to the amount of molten metal 12 provided to an associated mold is achieved by positioning the bypass gap 60 between the bearing assembly 35 and the impeller 22. More particularly, in one embodiment, the motor 14 is operated by a programmable command rpm profile as illustrated by FIGURE 9. A command RPM profile is programmed into a controller to electrically communicate with the motor to rotate the impeller and force molten metal through the outlet 50 and into the metal delivery conduit such that the outlet of the metal delivery conduit is adapted to an associated mold. The programmable command RPM profile varies a signal to the motor in relation to the volumetric fill rate and geometry of the associated mold.

    [0028] With reference to FIGURE 10, in one example, an associated mold (not shown) includes a generally complex geometric area or riser to be filled by molten metal 12 such as aluminum. The metal delivery conduit or riser (not shown) is adapted to fill the associated mold with aluminum from the pump assembly 10. The pump assembly 10 is programmed with a command RPM profile, as illustrated in FIGURE 10, that is associated with the inner geometric volume of the associated mold. This profile controls a command voltage at the motor 14 to rotate the impeller 12 at a predetermined rotational rate to fill the associated mold in accordance with form mold limits 1 - 5 at predetermined times. More particularly, the bypass gap 60 allows an increase in the magnitude of command RPM required to provide the necessary head pressure of molten metal 12 to the associated mold. This assembly and method is advantageous when filling associated molds to form complex parts within molds with a complicated geometric arrangement as finer tuning of an amount of molten metal 12 provided by the pump assembly 10 is achieved. Examples of molded parts suitable for casting using the pump assembly disclosed herein include, but are not limited to, engine blocks, wheels and cylinder heads.


    Claims

    1. A molten metal pump assembly (10) to fill a mold with molten metal (12) comprised of aluminum, the pump assembly (10) comprising:

    an elongated shaft (16) connecting a motor (14) to an impeller (22), the impeller (22) being housed within a chamber (18) of a base member (20) such that rotation of the

    impeller (22) draws molten metal into the chamber (18) at an inlet (48) and forces molten metal through an outlet of the chamber, the impeller (22) including a first radial edge (32) spaced from a second radial edge (34) such that the first radial edge (32) is proximate the elongated shaft (16); and

    a bearing assembly (35) surrounding the impeller (22) within the chamber (18), the bearing assembly (35) including:

    a first bearing ring (36) adapted to support the rotation of the impeller (22) at the first radial edge (32);

    a second bearing ring (38) adapted to support the rotation of the impeller (22) at the second radial edge (34);

    characterized by

    at least one bypass gap (60) to a surrounding environment interposed between a portion of one of the first and second bearing rings and the associated first and second radial edges (32, 34),

    wherein the bypass gap (60) comprises a width between the second

    bearing ring (38) and the associated second radial edge (34) of the impeller which is at least about 1.25 x greater in width than a lubrication gap (62) between the first

    bearing ring (36) and the first radial edge (32) of the impeller, the bypass gap (60)

    being operative to manipulate a flow rate and a head pressure of the molten metal.


     
    2. The molten metal pump assembly (10) in accordance with claim 1, wherein molten metal leaks from the chamber (18) through the bypass gap (60) at a predetermined rate as the impeller (22) is rotated.
     
    3. The molten metal pump assembly (10) in accordance with claim 1, wherein the base member (20) includes a first side and an opposite second side such that the bypass gap (60) is between the second bearing ring (38) and second radial edge.
     
    4. The molten metal pump assembly (10) in accordance with claim 1, wherein the bypass gap (60) is adapted to reduce a head pressure of the associated molten metal at the outlet as the rotational rate of the impeller (22) is increased.
     


    Ansprüche

    1. Pumpenanordnung (10) für geschmolzenes Metall, um eine Gießform mit geschmolzenem Metall (12) zu füllen, das Aluminium enthält, wobei die Pumpenanordnung (10) Folgendes umfasst:

    eine längliche Welle (16), die einen Motor (14) mit einem Flügelrad (22) verbindet, wobei das Flügelrad (22) in einer Kammer (18) eines Basiselements (20) aufgenommen ist, so dass eine Drehung des Flügelrads (22) geschmolzenes Metall an einem Einlass (48) in die Kammer (18) saugt und geschmolzenes Metall durch einen Auslass der Kammer drängt, wobei das Flügelrad (22) eine erste radiale Kante (32), die von einer zweiten radialen Kante (34) beabstandet ist, aufweist, so dass sich die erste radiale Kante (32) in der Nähe der länglichen Welle (16) befindet; und

    eine Lageranordnung (35), die das Flügelrad (22) in der Kammer (18) umgibt, wobei die Lageranordnung (35) Folgendes umfasst:

    einen ersten Lagerring (36), der ausgelegt ist, die Drehung des Flügelrads (22) an der ersten radialen Kante (32) zu unterstützen;

    einen zweiten Lagerring (38), der ausgelegt ist, die Drehung des Flügelrads (22) an der zweiten radialen Kante (34) zu unterstützen;

    gekennzeichnet durch

    wenigstens einen Umgehungsspalt (60) zu einer umliegenden Umgebung, der zwischen einem Abschnitt des ersten oder des zweiten Lagerrings und der zugeordneten ersten oder zweiten radialen Kante (32, 34) angeordnet ist,

    wobei der Umgehungsspalt (60) eine Breite zwischen dem zweiten Lagerring (38) und der zugehörigen zweiten radialen Kante (34) des Flügelrads aufweist, die wenigstens etwa der 1,25-fachen Breite eines Schmierungsspalts (62) zwischen dem ersten Lagerring (36) und der ersten radialen Kante (32) des Flügelrads beträgt, wobei die Wirkung des Umgehungsspalts (60) darin besteht, eine Durchflussmenge und einen Förderdruck des geschmolzenen Metalls zu beeinflussen.


     
    2. Pumpenanordnung (10) für geschmolzenes Metall nach Anspruch 1, wobei geschmolzenes Metall durch den Umgehungsspalt (60) mit einer festgelegten Durchflussmenge aus der Kammer (18) austritt, wenn das Flügelrad (22) gedreht wird.
     
    3. Pumpenanordnung (10) für geschmolzenes Metall nach Anspruch 1, wobei das Basiselement (20) eine erste Seite und eine gegenüberliegende zweite Seite umfasst, so dass der Umgehungsspalt (60) zwischen dem zweiten Lagerring (38) und der zweiten radialen Kante liegt.
     
    4. Pumpenanordnung (10) für geschmolzenes Metall nach Anspruch 1, wobei der Umgehungsspalt (60) ausgelegt ist, einen Förderdruck des zugehörigen geschmolzenen Metalls am Auslass zu reduzieren, wenn die Drehzahl des Flügelrads (22) erhöht wird.
     


    Revendications

    1. Ensemble pompe à métal en fusion (10) pour remplir un moule avec un métal en fusion (12) constitué d'aluminium, l'ensemble pompe (10) comprenant :

    un arbre allongé (16) reliant un moteur (14) à une roue (22), la roue (22) étant logée à l'intérieur d'une chambre (18) d'un organe de base (20) de sorte qu'une rotation de la roue (22) tire du métal en fusion dans la chambre (18) au niveau d'une entrée (48) et force du métal en fusion à travers une sortie de la chambre, la roue (22) comportant un premier bord radial (32) espacé d'un second bord radial (34) de sorte que le premier bord radial (32) soit à proximité de l'arbre allongé (16) ; et

    un ensemble palier (35) entourant la roue (22) à l'intérieur de la chambre (18), l'ensemble palier (35) comportant :

    une première bague de palier (36) apte à supporter la rotation de la roue (22) au niveau du premier bord radial (32) ;

    une seconde bague de palier (38) apte à supporter la rotation de la roue (22) au niveau du second bord radial (34) ;

    caractérisé par

    au moins un espacement de contournement (60) vers un environnement environnant interposé entre une portion de l'une parmi les première et seconde bagues de palier et les premier et second bords radiaux (32, 34) associés, dans lequel l'espacement de contournement (60) comprend une largeur entre la seconde bague de palier (38) et le second bord radial (34) associé de la roue qui est environ 1,25 fois plus grande qu'une largeur d'un espacement de lubrification (62) entre la première bague de palier (36) et le premier bord radial (32) de la roue, l'espacement de contournement (60) étant opérationnel pour réguler un débit et une pression de refoulement du métal en fusion.


     
    2. Ensemble pompe à métal en fusion (10) selon la revendication 1, dans lequel le métal en fusion fuit depuis la chambre (18) à travers l'espacement de contournement (60) à un débit prédéterminé au fur et à mesure de la rotation de roue (22).
     
    3. Ensemble pompe à métal en fusion (10) selon la revendication 1, dans lequel l'organe de base (20) comporte un premier côté et un second côté opposé de sorte que l'espacement de contournement (60) soit entre la seconde bague de palier (38) et le second bord radial.
     
    4. Ensemble pompe à métal en fusion (10) selon la revendication 1, dans lequel l'espacement de contournement (60) est apte à réduire une pression de refoulement du métal en fusion associé au niveau de la sortie au fur et à mesure de l'augmentation du régime de rotation de la roue (22).
     




    Drawing


























    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description