US20140341764A1 - Wet rotor pump - Google Patents
Wet rotor pump Download PDFInfo
- Publication number
- US20140341764A1 US20140341764A1 US14/373,205 US201314373205A US2014341764A1 US 20140341764 A1 US20140341764 A1 US 20140341764A1 US 201314373205 A US201314373205 A US 201314373205A US 2014341764 A1 US2014341764 A1 US 2014341764A1
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- United States
- Prior art keywords
- bearing
- impeller
- rotor pump
- stator
- pump according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D13/00—Pumping installations or systems
- F04D13/02—Units comprising pumps and their driving means
- F04D13/06—Units comprising pumps and their driving means the pump being electrically driven
- F04D13/0606—Canned motor pumps
- F04D13/0633—Details of the bearings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D13/00—Pumping installations or systems
- F04D13/02—Units comprising pumps and their driving means
- F04D13/021—Units comprising pumps and their driving means containing a coupling
- F04D13/024—Units comprising pumps and their driving means containing a coupling a magnetic coupling
- F04D13/026—Details of the bearings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D1/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D13/00—Pumping installations or systems
- F04D13/02—Units comprising pumps and their driving means
- F04D13/06—Units comprising pumps and their driving means the pump being electrically driven
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D13/00—Pumping installations or systems
- F04D13/02—Units comprising pumps and their driving means
- F04D13/06—Units comprising pumps and their driving means the pump being electrically driven
- F04D13/0606—Canned motor pumps
- F04D13/064—Details of the magnetic circuit
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D13/00—Pumping installations or systems
- F04D13/02—Units comprising pumps and their driving means
- F04D13/06—Units comprising pumps and their driving means the pump being electrically driven
- F04D13/0646—Units comprising pumps and their driving means the pump being electrically driven the hollow pump or motor shaft being the conduit for the working fluid
Definitions
- the invention relates to a wet rotor pump for pumping a fluid, in particular a liquid.
- the wet rotor pump comprises a rotor, which is connected to an impeller and is disposed in a wet zone, through which a pumped fluid flows.
- the wet zone is separated from a dry zone, in which the stator is disposed.
- the wet zone is demarcated from the dry zone by means of a printed circuit board, the electric lines of which form the stator such that the printed circuit board functions simultaneously as a containment shell.
- Further embodiments of wet rotor pumps are described in WO 2006/137496 A1, WO 00/37804, EP 1 130 741 A2, US005332374A and US 2002/0166520.
- Document DE 102 03 778 A1 makes known an electrically driven pump, which comprises an electric drive motor embodied as a disk rotor.
- the magnetic ring of the drive motor is disposed in a region through which fluid flows.
- Document EP 0 401 761 A2 describes a magnetic-drive pump, in which an impeller, in which a permanent magnet is embedded, is set into rotation by means of a magnetic force from outside the impeller.
- the magnetic drive mechanism is accommodated in a region of the pump housing that does not come into contact with a fluid, wherein the drive mechanism is oriented such that said drive mechanism is positioned opposite the impeller along the rotational axis of the impeller.
- Axial flux motors are also known per se from the related art.
- the magnetic flux extends in the air gap of the motor in the axial direction, cf. DE 100 53 400 A1 or DE 1 613 626, for example.
- the problem addressed by the invention is that of creating an improved wet rotor pump.
- a wet rotor pump is created, in which an inlet line for the fluid extends through the stator, the containment shell, and the bearing for the impeller.
- the motor is designed as an axial flux motor and has the advantage, in particular, that the wet rotor pump has a particularly compact design, i.e. a low overall height, combined with high power density.
- Embodiments of the invention are furthermore particularly advantageous since the bearing functions simultaneously as a seal at the transition between the suction side and the pressure side of the wet rotor pump. The losses due to leakage are minimized due to the relatively small gap widths and the low tolerances of the bearing.
- the fluid enters through a central opening in the containment shell.
- the containment shell can form an inlet connecting piece in particular.
- the stator is formed in the shape of a torus.
- the stator can comprise an annular stator tooth receptacle, on which stator teeth are disposed.
- the stator teeth can be attached to the stator tooth receptacle by means of bonding, for example.
- each of the stator teeth has a receiving region for a coil.
- Each of the stator teeth has an enlarged cross section at the end on the air-gap side. This has the advantage that the magnetic field is approximately homogeneous in a larger region within the air gap and therefore completely encloses the rotor magnets, which are narrower in the radial direction, thereby supporting the self-centering of the impeller in order to hereby support the self-centering of the impeller.
- air gap refers to the separation between the ends of the stator teeth and the rotor, even if the gap contains no air or not only air, e.g. the fluid as well.
- the power electronics which are used to control the coils of the stator, are disposed within the space circumscribed by the stator and the containment shell, as on an annular printed circuit board, for example.
- the overall height of the wet rotor pump can be further reduced in this manner.
- the containment shell is formed by an annular disk, which extends into the air gap between the stator and the rotor and separates the dry zone of the wet rotor pump from the wet zone.
- the annular disk has a central opening, at which the inlet connecting piece is disposed, which said inlet connecting piece extends through the center of the stator.
- the bearing for the impeller is disposed at the end region of the inlet connecting piece on the disk side, through which the fluid flows into the wet zone after having flowed through the dry zone, through the inlet line.
- the disk and the inlet connecting piece can be formed as one piece, in particular as a plastic injection-molded part.
- the containment shell can be embodied, in particular, as a plastic part (e.g. made of PPS/GFK/CFK) or as a non-magnetic, metallic part.
- the bearing is designed as a plain bearing, wherein a bearing bush of the plain bearing is disposed at the end region of the inlet connecting piece on the disk side, and a plain-bearing element of the plain bearing is attached to the impeller.
- a sliding surface of the plain-bearing element engages in the bearing bush such that radial support is provided.
- a further sliding surface can be provided on the bearing for additional axial support on one side in order to absorb the magnetic attraction force of the stator, which acts on the impeller via the rotor.
- Embodiments of the invention are particularly advantageous since, due to the axial flux motor on the impeller, a magnetic attraction force is exerted in the direction toward the stator such that the impeller requires support on only one side. This simplifies the design and further reduces the required overall height of the wet rotor pump.
- the plain-bearing element has passage holes in the radial direction, such as lubrication holes approximately 1 mm in size, for example, which are used to direct a very small portion of the volume flow of the fluid through the bearing in order to provide additional lubrication of said bearing.
- the bearing is coated with a combination of diamond-like carbon and silicon carbide (SiC), in order to ensure a particularly long service life of the bearing.
- SiC silicon carbide
- the bearing is designed as a combination of a plain bearing and a rolling bearing, which is designed to provide axial and radial support of the impeller.
- the rolling bearing is used to absorb the axial forces, while the plain bearing is used to absorb the radial forces, which said plain bearing is formed with consideration for hydrodynamic aspects.
- Embodiments of the invention are particularly advantageous, since strong forces can occur in the axial direction, in particular, due to the attraction of stator and rotor magnets, which said forces can result in a high amount of wear in a plain bearing.
- a rolling bearing is characterized by low friction, primarily in the form of rolling friction, and therefore the wear on the bearing is reduced as compared to a plain bearing.
- the rolling bearing is formed by bearing shells, which have running surfaces for accommodating rolling elements, and rolling elements.
- a first bearing shell is attached to the impeller, while a second bearing shell is attached to the containment shell.
- the rolling elements are located in the space circumscribed by the running surfaces of the bearing shells.
- the plain bearing is formed on the impeller side by the outer jacket surface of the first bearing shell, and by the jacket surface of the containment shell.
- the plain bearing is formed by the inner jacket surface of the second bearing shell and the jacket surface of the impeller.
- Embodiments are particularly advantageous, since the bearing shells are part of the plain bearing and are part of the rolling bearing. Therefore, this is a hybrid bearing. This arrangement results in a bearing for a wet rotor pump that is very compact and, simultaneously, has a long service life and is robust.
- the jacket surfaces and/or the running surfaces of the bearing shells and/or the rolling elements are coated with silicon carbide (SiC) and/or diamond-like carbon (DLC) and/or silicon-doped DLC.
- the bearing is embodied as a combination of a plain bearing and a magnetic bearing, which is designed to provide radial support of the impeller.
- the magnetic bearing is used to absorb axial forces, while the plain bearing is used to absorb radial forces, which said plain bearing is formed with consideration for hydrodynamic aspects.
- Embodiments of the invention are particularly advantageous, since a magnetic bearing is characterized by friction that ideally disappears, which results in a markedly longer service life of the bearing as compared to a plain bearing.
- the efficiency of the wet rotor pump increases due to the very low losses due to friction.
- the magnetic bearing is formed by magnetic rings.
- a first magnetic ring is attached to the impeller, and a second magnetic ring is attached to the containment shell.
- the magnetization of the magnetic rings is configured such that, in the state in which said magnetic rings are installed in the wet rotor pump, these repel one another in the axial direction.
- the plain bearing is formed on the impeller side by the outer jacket surface of the first magnetic ring, and by the jacket surface of the containment shell.
- the plain bearing is formed by the inner jacket surface of the second magnetic ring and the jacket surface of the impeller.
- Embodiments are particularly advantageous, since the magnetic rings are part of the plain bearing and are part of the magnetic bearing. Therefore, this is a hybrid bearing. This arrangement results in a bearing for a wet rotor pump that is very compact and, simultaneously, has a long service life and is robust.
- the jacket surfaces of the magnetic rings are coated with silicon carbide (SiC) and/or diamond-like carbon (DLC) and/or silicon-doped DLC.
- the bearing is protected by a fine-strand filter to ensure that particles do not enter the bearing.
- the bearing is protected from damage by particles that could be carried along in the medium.
- the rotor is formed by a permanent-magnet material, namely samarium cobalt (SmCo).
- a permanent-magnet material namely samarium cobalt (SmCo).
- Samarium cobalt can be used at high temperatures without negatively affecting the retentivity of the magnetization.
- the fluid can have a temperature of up to 200° C., for example.
- Samarium cobalt has excellent corrosion characteristics and can be directly exposed to the fluid with simple corrosion protection or without corrosion protection.
- the magnetic material can be disposed at the outermost edge of the periphery of the impeller or the drive disk, thereby permitting the permanent-magnet material to be positioned with a maximum radius.
- the permanent-magnet material forming the rotor can be disposed in the form of a plurality of individual, flat permanent magnets on the periphery of the impeller or in the form of a single magnetic ring having multipolar magnetization.
- the magnets or the magnetic ring can be attached directly at the periphery of the impeller or can be attached to the impeller via a drive disk.
- FIG. 1 shows an exploded view of a wet rotor pump according to the invention
- FIG. 2 a shows a side view of a single stator tooth
- FIG. 2 b shows a front view of the stator tooth according to FIG. 2 a
- FIG. 2 c shows a perspective view of the stator tooth according to FIG. 2 a
- FIG. 3 a shows a top view of the stator
- FIG. 3 b shows a sectional view of the stator
- FIG. 4 a shows a top view of an embodiment of the containment shell
- FIG. 4 b shows a sectional view of the containment shell according to FIG. 4 a
- FIG. 4 c shows a sectional view of the bearing bush of the containment shell according to FIG. 4 a
- FIG. 4 d shows a sectional view of an embodiment of the plain-bearing element of the impeller
- FIG. 5 a shows a top view of an embodiment of the rotor
- FIG. 5 b shows a sectional view of the rotor according to FIG. 5 a
- FIG. 6 shows a sectional view of an embodiment of the drive disk
- FIG. 7 shows a sectional view of an embodiment of the impeller
- FIG. 8 shows a sectional view of the wet rotor pump according to FIG. 1 , in the installed state
- FIG. 9 shows a sectional view of a wet rotor pump comprising a hybrid bearing formed of a rolling bearing and a plain bearing,
- FIG. 10 shows a sectional view of a further wet rotor pump according to the invention.
- FIG. 1 shows an exploded view of an embodiment of a wet rotor pump 100 according to the invention.
- the wet rotor pump 100 has a motor cover 102 , which has a circular end face 104 .
- An opening 106 for the inflow of a fluid 108 is located in the center of the end face 104 .
- the motor cover 102 is used to cover a stator 110 .
- the stator 110 has a stator tooth receptacle 112 , which has an annular shape and on which stator teeth 114 are disposed so as to form a circle.
- Each of the stator teeth has a receiving region 118 , on which a coil is wound (see FIGS. 2 and 3 ).
- the various coils of the stator teeth 114 are electrically connected to power electronics 120 , which are used to control the coils.
- the rotor of the axial flux motor is formed of a permanent-magnet material, which, in this case, is disposed on a ring 124 in the form of individual permanent magnets 122 (see FIG. 5 ).
- the permanent magnets 122 have magnetization in the axial direction such that the magnetic flux also extends in the axial direction of the wet rotor pump 100 , namely between the ends 126 of the stator teeth 114 and the permanent magnets 122 , across an air gap that exists between the ends 126 and the permanent magnets 122 .
- a magnetic attraction force is exerted by the stator 110 on the permanent magnets 122 and, therefore, on an impeller 128 of the wet rotor pump 100 .
- a disk 130 of a containment shell 116 extends into the air gap between the ends 126 of the stator teeth 114 and the permanent magnets 122 .
- the disk 130 has recesses 132 , which accommodate the ends of the stator teeth 114 (see FIGS. 4 a , 4 b ).
- the bracings located between the recesses increase the mechanical stability of the motor design and make it possible to minimize the material thickness and, therefore, to minimize the air gap.
- the wall thickness of the containment shell 116 in the recesses 132 is between 0.7 mm and 0.2 mm, for example. Such a thin wall thickness reduces the air gap, which, in turn, increases efficiency and power while using the same certain quantity of rare earth magnets.
- the mechanical stability of the motor design is improved as a result.
- the disk 130 has an axial opening, on which an inlet connecting piece 134 is disposed.
- the inlet connecting piece 134 extends through the stator 110 and the opening 106 of the motor cover 102 , thereby allowing the fluid 108 to flow in via the inlet connecting piece 134 .
- a space is circumscribed by the containment shell 116 and the stator 110 , in which the power electronics 120 can be disposed, for example on an annular printed circuit board 136 , the outer radius of which is limited by the recesses 132 , and the inner radius of which is limited by the wall of the inlet connecting piece 134 .
- This printed circuit board 136 can carry the various electric and electronic components that form the power electronics 120 . Since this is disposed in the dry zone of the wet rotor pump 100 , special encapsulation of the power electronics 120 is not absolutely necessary.
- An attachment region 138 is disposed on the inlet connecting piece 134 with axial separation from the disk 130 , to which said attachment region the motor cover 102 is attached, by means of screwed connections, for example.
- the stator 110 is then held between the motor cover 102 and the disk 130 , wherein the ends 126 of the stator teeth 114 extend into the recesses 132 and are held there in a form-fit manner, for example.
- the attachment region 138 can be annular, for example, as shown in FIG. 1 , and can have internal threads for forming screwed connections for attaching the motor cover 102 , which has corresponding holes 140 for passage of the screws.
- the tubular extension of the containment shell having a disk-shaped portion toward the top is also used to center the stator flux return ring, i.e. the stator tooth receptacle 112 .
- the wet rotor pump has a first housing half 142 and a second housing half 144 , by means of which the housing of the wet rotor pump 100 is formed.
- the housing half 142 has an opening 146 in the center thereof, which adjoins the end of the inlet connecting piece 134 on the air-gap side, thereby allowing fluid 108 to flow from the inlet connecting piece 134 through the opening 146 .
- the disk 130 is attached to the outer side of the housing half 142 , by means of screwed connections, for example, on an annular attachment region 148 of the housing half 142 .
- the inlet line is therefore formed by the inlet connecting piece 134 with the bearing bush 156 disposed at the end thereof on the air-gap side.
- the impeller 128 is located between these housing halves 142 and 144 .
- the rotor is formed at the impeller 128 by virtue of the fact that the ring 124 comprising the permanent magnets 122 is connected to the impeller 128 via a drive disk 150 , by means of screws 153 , for example.
- the permanent magnets 122 can also be disposed directly on the impeller 128 .
- the permanent magnets 122 can be disposed between the ring 124 and the drive disk 150 .
- the impeller has an extension 152 for accommodating a plain-bearing element 154 , which, together with a bearing bush 156 , forms a plain bearing for the radial support of the impeller 128 (see FIGS. 4 c and 4 d ).
- the bearing supports the impeller 128 such that said impeller has one axial degree of freedom by virtue of the fact that a magnetic attraction force is exerted on the impeller 128 via the permanent magnets 122 in the axial direction toward the stator 110 , whereby the axial position of the impeller 128 is also determined.
- the bearing formed by the plain-bearing element 154 and the bearing bush 156 can be designed such that this forms an abutment for absorbing the magnetic attraction force on one side in the axial direction (see FIGS. 4 c and 4 d ).
- This magnetic attraction force of the stator 110 furthermore has a self-centering effect—during rotation—on the impeller 128 , which reduces the load on the plain bearing.
- the two housing halves 142 and 144 are connected to one another by means of screws or adhesive 158 .
- An outlet 160 for the fluid 108 is formed in this manner.
- Embodiments of the invention are particularly advantageous since the fluid 108 flows in on the stator side and, in fact, through the stator. Furthermore, due to the axial flux motor, support for the impeller is required on only one side, without a rotor shaft, which makes it possible overall to obtain a particularly compact design having a high power density.
- FIG. 2 a shows a front view of one of the stator teeth 126 according to the embodiment shown in FIG. 1 .
- the receiving region 118 of the stator tooth 126 accommodates a plurality of windings of a coil 162 , which is controlled by the power electronics 120 of the printed circuit board 136 .
- the receiving region 118 of the stator tooth 114 is closed on the air-gap side by the end 126 of the stator tooth 114 , which has a larger cross section than the receiving region 118 .
- This larger cross section has the advantage that the magnetic field is widened accordingly in the air gap and is approximately homogeneous in a larger spatial region.
- the self-centering of the impeller 128 (see FIG. 1 ) is supported as a result, since the permanent magnets 122 of the rotor have a width in the radial direction that is shorter than the stator flux width.
- FIG. 2 a shows, as an example, how one of the permanent magnets 122 is disposed on the impeller relative to the stator tooth 114 .
- the permanent magnet 122 is shorter in the radial direction than the extension of the end 126 of the stator tooth 114 in the radial direction, and therefore the stator tooth extends beyond the permanent magnet 122 .
- the permanent magnet 122 is positioned in the center underneath the receiving region 118 , for example.
- the stator tooth 114 has a slot-shaped recess 162 in the upper region thereof, which is used to attach the stator tooth 114 to the stator tooth receptacle 112 (see FIG. 3 ).
- FIG. 2 b shows the stator tooth 114 in a front view
- FIG. 2 c shows said stator tooth in a perspective view.
- FIG. 3 a shows a top view of the stator 110 having the annular stator tooth receptacle 112 , which has an opening in the center thereof, through which the inlet connecting piece 134 extends (see FIG. 1 ).
- the stator teeth 114 including the recesses 162 thereof, are attached on the periphery of the stator tooth receptacle 112 . This can be achieved by the recess 162 and/or the stator tooth receptacle 112 functioning as bonding surfaces in order to bond the stator tooth 114 , including the recess 162 thereof, on the edge of the stator tooth receptacle 112 .
- FIG. 3 b shows a corresponding sectional view.
- FIG. 4 a shows a top view of the containment shell 116 , through the inlet connecting piece 134 of which the fluid can flow in.
- FIG. 4 b shows a sectional view of the containment shell 116 .
- the end of the inlet connecting piece 134 on the air-gap side is designed to accommodate a bearing bush 156 , as shown in FIG. 4 c .
- an inner radius R is formed at the end region of the inlet connecting piece 134 , into which the bearing bush 156 can be inserted and affixed, for example with the aid of a press fit.
- a plain-bearing element 154 is attached to the extension 152 of the impeller 128 (see FIG. 1 ) and functions as the counterpart to the bearing bush 156 .
- the plain-bearing element 154 is annular and has an end section 164 , the outer diameter of which is reduced such that a circumferential edge 166 is formed externally on the plain-bearing element 154 .
- the bearing bush 156 therefore accommodates the end section 164 of the plain-bearing element 154 , wherein the inner side of the bearing bush 156 and the outer side of the end section 164 of the plain-bearing element 154 form the sliding surfaces of the plain bearing.
- the impeller 128 is thereby radially supported.
- the axial degree of freedom of the impeller 128 is limited by the circumferential edge 166 .
- the impeller 128 is drawn in the direction of the stator 110 by the magnetic forces that occur, the edge 166 impacts the front side of the bearing bush 156 , thereby forming an abutment for absorbing this magnetic attraction force.
- the impeller 128 is therefore supported in the containment shell 116 such that said impeller has one axial degree of freedom, i.e. axial play, the axial position of the impeller 128 is defined by the magnetic attraction force during operation of the axial flux motor.
- At least one of the sliding surfaces of the plain bearing is coated with diamond-like carbon (DLC) and silicon carbide (SiC) or a combination of DLC and SiC, in order to extend the service life of the bearing.
- DLC diamond-like carbon
- SiC silicon carbide
- Embodiments of the invention are particularly advantageous in which the fluid 108 is suctioned through the bearing, which also contributes to the compact design of the wet rotor pump.
- the plain bearing can have a very narrow gap, which is approximately 0.01 mm to 0.03 mm, for example, and is therefore also simultaneously very well sealed.
- the plain-bearing element 154 can have one or more radial openings, such as lubrication holes approximately 1 mm in size, for example. By means of these openings, a very small portion of the volume flow of the fluid 108 is directed between the sliding surfaces of the bearing in order to provide additional lubrication of said bearing.
- This at least one opening is preferably disposed in the end section 164 of the plain-bearing element 154 and is directed toward the center.
- FIG. 5 shows a top view of the rotor having the permanent magnets 122 , which are disposed on the ring 124 .
- the permanent magnets 122 are preferably formed of samarium cobalt, which has various advantages:
- Samarium cobalt can be used in relatively high temperatures without the retentivity being negatively affected thereby; the fluid 108 can have a temperature of up to 200° C., in particular.
- Samarium cobalt has excellent corrosion characteristics and can therefore be exposed to the fluid 108 without coating and without encapsulation.
- said permanent magnets 122 can be positioned at a maximum distance away from the rotational axis, thereby ensuring that maximum torque and maximum motor output result for a given amount of magnetic material.
- the permanent magnets 122 can also be used for the permanent magnets 122 , such as neodymium iron boron.
- FIG. 6 shows the drive disk 150 in a cross section.
- the drive disk 150 is used to mechanically connect the rotor, i.e. the ring 124 having the permanent magnets 122 , to the impeller 128 , wherein the extension 152 of the impeller 128 extends through the drive disk 150 , as shown in FIG. 1 .
- FIG. 7 shows a sectional view of the impeller 128 .
- FIG. 8 shows a sectional view of the wet rotor pump 100 in the installed state.
- the coils of the stator teeth 114 are controlled by the power electronics 120 such that torque acts on the impeller 128 via the rotor.
- the rotor then suctions the fluid 108 through the inlet connecting piece 134 and the bearing such that the fluid 108 is conveyed through the wet rotor pump 100 and exits said wet rotor pump at the outlet 160 .
- FIG. 9 shows a sectional view of a wet rotor pump according to the invention, wherein the impeller 128 is supported by a combination of a plain bearing and a rolling bearing.
- the rolling bearing is designed as a ball bearing. It is also feasible, however, to use other variants of rolling bearings, such as roller bearings, cone bearings, needle roller bearings, or the like.
- the rolling bearing is formed by two bearing shells 170 and 168 , which have running surfaces for accommodating rolling elements 172 .
- the lower bearing shell 168 is attached to the impeller 128
- the upper bearing shell 170 is attached to the containment shell.
- the bearing shells can be bonded, shrunk-fit or pressed onto the corresponding components, or fixedly screwed thereon.
- the rolling elements are located in the intermediate space between the bearing shells, which said intermediate space is circumscribed by the running surfaces of the bearing shells. If the pump is intended to be operated at high impeller speeds, the rolling bearings can be connected to one another by means of a cage in order to increase the stability of the bearing.
- the plain bearing is formed by an upper plain-bearing surface 174 between the upper bearing shell 170 and the jacket surface of the impeller 128 , and by a lower plain-bearing surface 176 between the lower bearing shell 168 and the containment shell 116 .
- the plain bearing has only slight bearing play at the bearing surface 174 in particular, thereby enabling a portion of the fluid 108 to enter the rolling bearing. The penetration of the rolling bearing by the pumped fluid can provide additional lubrication of the rolling bearing.
- the bearing play which can be considered to be an annular opening, is preferably protected by a fine-strand filter 178 , in order to ensure that foreign objects that can be contained in the pumped fluid are kept away from the bearing region.
- the fine-strand filter 178 is held in position by a clamping ring 180 .
- FIG. 10 shows a further embodiment of a wet rotor pump 200 according to the invention.
- This wet rotor pump differs substantially from the wet rotor pump shown in FIG. 9 by a different geometry and different dimensions of the housing 204 and the motor cover 216 . This is due to the fact that the rotor magnets 206 are now no longer attached to the drive disk, but rather are attached directly on the impeller 202 . In order to ensure that the distance between the lower end of the stator teeth 212 and the rotor magnets is still minimal, the stator teeth 212 have been lengthened in the vertical extension thereof. As a result, the containment shell 222 , including the suction connecting piece 218 , has a different shape.
- the stator tooth receptacle 214 is unchanged compared to the stator tooth receptacle of the wet rotor pump shown in FIG. 9 .
- a further difference between the wet rotor pump 200 and the wet rotor pump described with reference to FIG. 9 relates to the support of the impeller 202 in the containment shell 222 .
- the impeller 202 of the wet rotor pump 200 is supported in the axial direction by two magnetic rings, which are magnetized such that, in the installed state, said magnetic rings repel one another in the axial direction.
- a lower magnetic ring 208 is attached to the impeller 202
- an upper magnetic ring 210 is attached to the containment shell.
- the magnetic rings can be attached by means of bonding, screwing, shrink-fitting, press-fitting, or other attachment methods.
- the magnetic rings 208 and 210 comprise permanent magnets, such as neodymium iron boron (NdFeB) or samarium cobalt (SmCo), and are metallically completely encapsulated in an air- and water-tight manner.
- the encapsulation can be implemented by laser- or friction-welding of the encapsulation components, for example.
- the encapsulation of all sides that do not face one another comprises non-magnetic metal, such as stainless steel, for example, whereas the welded-on cover plate, i.e. the two sides that face one another, comprise soft magnetic material. The magnetic flux is thereby strengthened in the region of the cover plates.
- the thickness of the encapsulation can be between 1 mm and 2 mm, for example.
- the magnetic ring 208 which is pressed on on the impeller side, is manufactured in a manner similar to that of the lower bearing shell 168 of the wet rotor pump shown in FIG. 9 such that a hydrodynamic gap forms between the outer jacket surface of the magnetic ring 208 and the inner jacket surface of the containment shell 222 , which said hydrodynamic gap also functions as a sealing gap.
- the magnetic rings 208 and 210 are preferably magnetized and oriented such that the repellent effect between the magnetic rings is approximately proportional to the square of the distance between the magnetic rings.
- the thickness of the magnetic rings 208 and 210 is preferably designed such that, in the non-operative state of the wet rotor pump 200 , equilibrium sets in between the attractive force between the rotor magnets 206 and the stator teeth 212 and the repulsive force between the magnetic rings 208 and 210 .
- an air gap of approximately 1 mm preferably forms between the lower end of the stator teeth 212 and the rotor magnets 206
- an air gap having a width of 3 mm forms between the magnetic rings 208 and 210 .
- the magnetic field strength generated by the magnetic rings 208 and 210 is therefore stronger than the field strength between the rotor magnets 206 and the stator teeth 212 .
- the pressure differential between the suction side and the pressure side of the wet rotor pump 200 and, therefore, the contact pressure of the impeller 202 increases upwardly, in the direction toward the suction connecting piece 218 .
- the contact pressure on the mutually repellent magnetic rings 208 and 210 also increases such that the air gap between the magnetic rings 208 and 210 and the air gap between the rotor magnets 206 and the stator teeth 12 is reduced. The reduction of the air gaps continues until a new equilibrium has set in between the contact pressure, the attractive force between the rotor magnets 206 and the stator teeth 212 , and the repulsive force between the magnetic rings 208 and 210 .
- the performance limit of the wet rotor pump can be dimensioned such that the air gap between the rotor magnets 206 and the stator teeth 212 does not fall below a width of 0.2 mm.
- safety sliding surfaces 220 can be mounted on the rotor, which extend upwardly beyond the rotor magnets 206 by 0.2 mm, for example. In the event that the aforementioned performance limit is exceeded, said safety sliding surfaces can support the rotor at the containment shell 222 and prevent damage to the impeller 202 or the rotor magnets 206 .
Abstract
A wet rotor pump with an axial flux motor that includes a stator, a containment shell, and a rotor. The stator and the containment shell are arranged in a dry zone while the rotor on an impeller is arranged in a wet zone. The wet rotor pump further has an inlet line for a fluid to be pumped by the impeller, and a bearing for the impeller. Said bearing is arranged at one end of the inlet line and supports the impeller in such a way that the impeller has an axial degree of freedom. The inlet line extends through the stator, the containment shell, and the bearing in the axial direction.
Description
- The invention relates to a wet rotor pump for pumping a fluid, in particular a liquid.
- Document DE 10 2005 015 213 A1 makes known a wet rotor pump. The wet rotor pump comprises a rotor, which is connected to an impeller and is disposed in a wet zone, through which a pumped fluid flows. The wet zone is separated from a dry zone, in which the stator is disposed. The wet zone is demarcated from the dry zone by means of a printed circuit board, the electric lines of which form the stator such that the printed circuit board functions simultaneously as a containment shell. Further embodiments of wet rotor pumps are described in WO 2006/137496 A1, WO 00/37804, EP 1 130 741 A2, US005332374A and US 2002/0166520.
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Document DE 102 03 778 A1 makes known an electrically driven pump, which comprises an electric drive motor embodied as a disk rotor. The magnetic ring of the drive motor is disposed in a region through which fluid flows. -
Document EP 0 401 761 A2 describes a magnetic-drive pump, in which an impeller, in which a permanent magnet is embedded, is set into rotation by means of a magnetic force from outside the impeller. The magnetic drive mechanism is accommodated in a region of the pump housing that does not come into contact with a fluid, wherein the drive mechanism is oriented such that said drive mechanism is positioned opposite the impeller along the rotational axis of the impeller. - Axial flux motors are also known per se from the related art. In an axial flux motor, the magnetic flux extends in the air gap of the motor in the axial direction, cf.
DE 100 53 400 A1 or DE 1 613 626, for example. - The problem addressed by the invention is that of creating an improved wet rotor pump.
- The problem addressed by the invention is solved by the features of claim 1. Embodiments of the invention are set forth in the dependent claims.
- According to embodiments of the invention, a wet rotor pump is created, in which an inlet line for the fluid extends through the stator, the containment shell, and the bearing for the impeller. Such a geometry is made possible by designing the motor as an axial flux motor and has the advantage, in particular, that the wet rotor pump has a particularly compact design, i.e. a low overall height, combined with high power density.
- Embodiments of the invention are furthermore particularly advantageous since the bearing functions simultaneously as a seal at the transition between the suction side and the pressure side of the wet rotor pump. The losses due to leakage are minimized due to the relatively small gap widths and the low tolerances of the bearing.
- According to an embodiment of the invention, the fluid enters through a central opening in the containment shell. The containment shell can form an inlet connecting piece in particular.
- According to an embodiment of the invention, the stator is formed in the shape of a torus. In particular, the stator can comprise an annular stator tooth receptacle, on which stator teeth are disposed. The stator teeth can be attached to the stator tooth receptacle by means of bonding, for example.
- According to an embodiment of the invention, each of the stator teeth has a receiving region for a coil. Each of the stator teeth has an enlarged cross section at the end on the air-gap side. This has the advantage that the magnetic field is approximately homogeneous in a larger region within the air gap and therefore completely encloses the rotor magnets, which are narrower in the radial direction, thereby supporting the self-centering of the impeller in order to hereby support the self-centering of the impeller. In this case, “air gap” refers to the separation between the ends of the stator teeth and the rotor, even if the gap contains no air or not only air, e.g. the fluid as well.
- According to an embodiment of the invention, the power electronics, which are used to control the coils of the stator, are disposed within the space circumscribed by the stator and the containment shell, as on an annular printed circuit board, for example. The overall height of the wet rotor pump can be further reduced in this manner.
- According to an embodiment of the invention, the containment shell is formed by an annular disk, which extends into the air gap between the stator and the rotor and separates the dry zone of the wet rotor pump from the wet zone. The annular disk has a central opening, at which the inlet connecting piece is disposed, which said inlet connecting piece extends through the center of the stator. The bearing for the impeller is disposed at the end region of the inlet connecting piece on the disk side, through which the fluid flows into the wet zone after having flowed through the dry zone, through the inlet line. The disk and the inlet connecting piece can be formed as one piece, in particular as a plastic injection-molded part. The containment shell can be embodied, in particular, as a plastic part (e.g. made of PPS/GFK/CFK) or as a non-magnetic, metallic part.
- According to an embodiment of the invention, the bearing is designed as a plain bearing, wherein a bearing bush of the plain bearing is disposed at the end region of the inlet connecting piece on the disk side, and a plain-bearing element of the plain bearing is attached to the impeller. A sliding surface of the plain-bearing element engages in the bearing bush such that radial support is provided. A further sliding surface can be provided on the bearing for additional axial support on one side in order to absorb the magnetic attraction force of the stator, which acts on the impeller via the rotor.
- Embodiments of the invention are particularly advantageous since, due to the axial flux motor on the impeller, a magnetic attraction force is exerted in the direction toward the stator such that the impeller requires support on only one side. This simplifies the design and further reduces the required overall height of the wet rotor pump.
- According to an embodiment of the invention, the plain-bearing element has passage holes in the radial direction, such as lubrication holes approximately 1 mm in size, for example, which are used to direct a very small portion of the volume flow of the fluid through the bearing in order to provide additional lubrication of said bearing.
- According to an embodiment of the invention, the bearing is coated with a combination of diamond-like carbon and silicon carbide (SiC), in order to ensure a particularly long service life of the bearing.
- According to an embodiment of the invention, the bearing is designed as a combination of a plain bearing and a rolling bearing, which is designed to provide axial and radial support of the impeller. The rolling bearing is used to absorb the axial forces, while the plain bearing is used to absorb the radial forces, which said plain bearing is formed with consideration for hydrodynamic aspects.
- Embodiments of the invention are particularly advantageous, since strong forces can occur in the axial direction, in particular, due to the attraction of stator and rotor magnets, which said forces can result in a high amount of wear in a plain bearing. A rolling bearing, however, is characterized by low friction, primarily in the form of rolling friction, and therefore the wear on the bearing is reduced as compared to a plain bearing.
- According to an embodiment of the invention, the rolling bearing is formed by bearing shells, which have running surfaces for accommodating rolling elements, and rolling elements. In this case, a first bearing shell is attached to the impeller, while a second bearing shell is attached to the containment shell. The rolling elements are located in the space circumscribed by the running surfaces of the bearing shells.
- According to an embodiment of the invention, the plain bearing is formed on the impeller side by the outer jacket surface of the first bearing shell, and by the jacket surface of the containment shell. On the containment-shell side, the plain bearing is formed by the inner jacket surface of the second bearing shell and the jacket surface of the impeller.
- Embodiments are particularly advantageous, since the bearing shells are part of the plain bearing and are part of the rolling bearing. Therefore, this is a hybrid bearing. This arrangement results in a bearing for a wet rotor pump that is very compact and, simultaneously, has a long service life and is robust.
- In order to further increase the service life of the bearing, in an embodiment of the invention, the jacket surfaces and/or the running surfaces of the bearing shells and/or the rolling elements are coated with silicon carbide (SiC) and/or diamond-like carbon (DLC) and/or silicon-doped DLC.
- According to an embodiment of the invention, the bearing is embodied as a combination of a plain bearing and a magnetic bearing, which is designed to provide radial support of the impeller. The magnetic bearing is used to absorb axial forces, while the plain bearing is used to absorb radial forces, which said plain bearing is formed with consideration for hydrodynamic aspects.
- Embodiments of the invention are particularly advantageous, since a magnetic bearing is characterized by friction that ideally disappears, which results in a markedly longer service life of the bearing as compared to a plain bearing. In addition, the efficiency of the wet rotor pump increases due to the very low losses due to friction.
- According to an embodiment of the invention, the magnetic bearing is formed by magnetic rings. In this case, a first magnetic ring is attached to the impeller, and a second magnetic ring is attached to the containment shell. The magnetization of the magnetic rings is configured such that, in the state in which said magnetic rings are installed in the wet rotor pump, these repel one another in the axial direction.
- According to an embodiment of the invention, the plain bearing is formed on the impeller side by the outer jacket surface of the first magnetic ring, and by the jacket surface of the containment shell. On the containment-shell side, the plain bearing is formed by the inner jacket surface of the second magnetic ring and the jacket surface of the impeller.
- Embodiments are particularly advantageous, since the magnetic rings are part of the plain bearing and are part of the magnetic bearing. Therefore, this is a hybrid bearing. This arrangement results in a bearing for a wet rotor pump that is very compact and, simultaneously, has a long service life and is robust.
- In order to further increase the service life of the bearing, in an embodiment of the invention, the jacket surfaces of the magnetic rings are coated with silicon carbide (SiC) and/or diamond-like carbon (DLC) and/or silicon-doped DLC.
- According to a further embodiment, the bearing is protected by a fine-strand filter to ensure that particles do not enter the bearing. As a result, the bearing is protected from damage by particles that could be carried along in the medium.
- According to an embodiment of the invention, the rotor is formed by a permanent-magnet material, namely samarium cobalt (SmCo). This is advantageous for a plurality of reasons:
- Samarium cobalt can be used at high temperatures without negatively affecting the retentivity of the magnetization. As a result, the fluid can have a temperature of up to 200° C., for example.
- Samarium cobalt has excellent corrosion characteristics and can be directly exposed to the fluid with simple corrosion protection or without corrosion protection.
- Since samarium cobalt does not need to be encapsulated in stainless steel, for example, for corrosion protection, the magnetic material can be disposed at the outermost edge of the periphery of the impeller or the drive disk, thereby permitting the permanent-magnet material to be positioned with a maximum radius.
- The permanent-magnet material forming the rotor can be disposed in the form of a plurality of individual, flat permanent magnets on the periphery of the impeller or in the form of a single magnetic ring having multipolar magnetization. In particular, the magnets or the magnetic ring can be attached directly at the periphery of the impeller or can be attached to the impeller via a drive disk.
- Embodiments of the invention are explained in greater detail in the following with reference to the drawings. In the drawings:
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FIG. 1 shows an exploded view of a wet rotor pump according to the invention, -
FIG. 2 a shows a side view of a single stator tooth, -
FIG. 2 b shows a front view of the stator tooth according toFIG. 2 a, -
FIG. 2 c shows a perspective view of the stator tooth according toFIG. 2 a, -
FIG. 3 a shows a top view of the stator, -
FIG. 3 b shows a sectional view of the stator, -
FIG. 4 a shows a top view of an embodiment of the containment shell, -
FIG. 4 b shows a sectional view of the containment shell according toFIG. 4 a, -
FIG. 4 c shows a sectional view of the bearing bush of the containment shell according toFIG. 4 a, -
FIG. 4 d shows a sectional view of an embodiment of the plain-bearing element of the impeller, -
FIG. 5 a shows a top view of an embodiment of the rotor, -
FIG. 5 b shows a sectional view of the rotor according toFIG. 5 a, -
FIG. 6 shows a sectional view of an embodiment of the drive disk, -
FIG. 7 shows a sectional view of an embodiment of the impeller, -
FIG. 8 shows a sectional view of the wet rotor pump according toFIG. 1 , in the installed state, -
FIG. 9 shows a sectional view of a wet rotor pump comprising a hybrid bearing formed of a rolling bearing and a plain bearing, -
FIG. 10 shows a sectional view of a further wet rotor pump according to the invention. - Elements of the following embodiments that correspond to one another or are identical are labelled with the same reference signs in each case.
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FIG. 1 shows an exploded view of an embodiment of awet rotor pump 100 according to the invention. Thewet rotor pump 100 has amotor cover 102, which has acircular end face 104. Anopening 106 for the inflow of a fluid 108 is located in the center of theend face 104. - The
motor cover 102 is used to cover astator 110. Thestator 110 has astator tooth receptacle 112, which has an annular shape and on whichstator teeth 114 are disposed so as to form a circle. Each of the stator teeth has a receivingregion 118, on which a coil is wound (seeFIGS. 2 and 3 ). - The various coils of the
stator teeth 114 are electrically connected topower electronics 120, which are used to control the coils. - In the embodiment considered here, the rotor of the axial flux motor is formed of a permanent-magnet material, which, in this case, is disposed on a
ring 124 in the form of individual permanent magnets 122 (seeFIG. 5 ). - The
permanent magnets 122 have magnetization in the axial direction such that the magnetic flux also extends in the axial direction of thewet rotor pump 100, namely between theends 126 of thestator teeth 114 and thepermanent magnets 122, across an air gap that exists between theends 126 and thepermanent magnets 122. As a result, a magnetic attraction force is exerted by thestator 110 on thepermanent magnets 122 and, therefore, on animpeller 128 of thewet rotor pump 100. - A
disk 130 of acontainment shell 116 extends into the air gap between theends 126 of thestator teeth 114 and thepermanent magnets 122. Thedisk 130 hasrecesses 132, which accommodate the ends of the stator teeth 114 (seeFIGS. 4 a, 4 b). The bracings located between the recesses increase the mechanical stability of the motor design and make it possible to minimize the material thickness and, therefore, to minimize the air gap. The wall thickness of thecontainment shell 116 in therecesses 132 is between 0.7 mm and 0.2 mm, for example. Such a thin wall thickness reduces the air gap, which, in turn, increases efficiency and power while using the same certain quantity of rare earth magnets. The mechanical stability of the motor design is improved as a result. - The
disk 130 has an axial opening, on which aninlet connecting piece 134 is disposed. - In the installed state of the wet rotor pump 100 (see
FIG. 8 ), theinlet connecting piece 134 extends through thestator 110 and theopening 106 of themotor cover 102, thereby allowing the fluid 108 to flow in via theinlet connecting piece 134. - A space is circumscribed by the
containment shell 116 and thestator 110, in which thepower electronics 120 can be disposed, for example on an annular printedcircuit board 136, the outer radius of which is limited by therecesses 132, and the inner radius of which is limited by the wall of theinlet connecting piece 134. This printedcircuit board 136 can carry the various electric and electronic components that form thepower electronics 120. Since this is disposed in the dry zone of thewet rotor pump 100, special encapsulation of thepower electronics 120 is not absolutely necessary. - An
attachment region 138 is disposed on theinlet connecting piece 134 with axial separation from thedisk 130, to which said attachment region themotor cover 102 is attached, by means of screwed connections, for example. Thestator 110 is then held between themotor cover 102 and thedisk 130, wherein theends 126 of thestator teeth 114 extend into therecesses 132 and are held there in a form-fit manner, for example. - The
attachment region 138 can be annular, for example, as shown inFIG. 1 , and can have internal threads for forming screwed connections for attaching themotor cover 102, which has correspondingholes 140 for passage of the screws. Simultaneously, the tubular extension of the containment shell having a disk-shaped portion toward the top is also used to center the stator flux return ring, i.e. thestator tooth receptacle 112. - The wet rotor pump has a
first housing half 142 and asecond housing half 144, by means of which the housing of thewet rotor pump 100 is formed. Thehousing half 142 has anopening 146 in the center thereof, which adjoins the end of theinlet connecting piece 134 on the air-gap side, thereby allowing fluid 108 to flow from theinlet connecting piece 134 through theopening 146. Thedisk 130 is attached to the outer side of thehousing half 142, by means of screwed connections, for example, on anannular attachment region 148 of thehousing half 142. In the embodiment considered here, the inlet line is therefore formed by theinlet connecting piece 134 with the bearingbush 156 disposed at the end thereof on the air-gap side. - The
impeller 128 is located between thesehousing halves impeller 128 by virtue of the fact that thering 124 comprising thepermanent magnets 122 is connected to theimpeller 128 via adrive disk 150, by means ofscrews 153, for example. According to an alternative embodiment, thepermanent magnets 122 can also be disposed directly on theimpeller 128. Furthermore, thepermanent magnets 122 can be disposed between thering 124 and thedrive disk 150. - The impeller has an
extension 152 for accommodating a plain-bearing element 154, which, together with abearing bush 156, forms a plain bearing for the radial support of the impeller 128 (seeFIGS. 4 c and 4 d). The bearing supports theimpeller 128 such that said impeller has one axial degree of freedom by virtue of the fact that a magnetic attraction force is exerted on theimpeller 128 via thepermanent magnets 122 in the axial direction toward thestator 110, whereby the axial position of theimpeller 128 is also determined. The bearing formed by the plain-bearing element 154 and thebearing bush 156 can be designed such that this forms an abutment for absorbing the magnetic attraction force on one side in the axial direction (seeFIGS. 4 c and 4 d). - This magnetic attraction force of the
stator 110 furthermore has a self-centering effect—during rotation—on theimpeller 128, which reduces the load on the plain bearing. - The two
housing halves - An
outlet 160 for the fluid 108 is formed in this manner. - Embodiments of the invention are particularly advantageous since the fluid 108 flows in on the stator side and, in fact, through the stator. Furthermore, due to the axial flux motor, support for the impeller is required on only one side, without a rotor shaft, which makes it possible overall to obtain a particularly compact design having a high power density.
-
FIG. 2 a shows a front view of one of thestator teeth 126 according to the embodiment shown inFIG. 1 . The receivingregion 118 of thestator tooth 126 accommodates a plurality of windings of acoil 162, which is controlled by thepower electronics 120 of the printedcircuit board 136. - The receiving
region 118 of thestator tooth 114 is closed on the air-gap side by theend 126 of thestator tooth 114, which has a larger cross section than the receivingregion 118. This larger cross section has the advantage that the magnetic field is widened accordingly in the air gap and is approximately homogeneous in a larger spatial region. The self-centering of the impeller 128 (seeFIG. 1 ) is supported as a result, since thepermanent magnets 122 of the rotor have a width in the radial direction that is shorter than the stator flux width. -
FIG. 2 a shows, as an example, how one of thepermanent magnets 122 is disposed on the impeller relative to thestator tooth 114. Thepermanent magnet 122 is shorter in the radial direction than the extension of theend 126 of thestator tooth 114 in the radial direction, and therefore the stator tooth extends beyond thepermanent magnet 122. Thepermanent magnet 122 is positioned in the center underneath the receivingregion 118, for example. - The
stator tooth 114 has a slot-shapedrecess 162 in the upper region thereof, which is used to attach thestator tooth 114 to the stator tooth receptacle 112 (seeFIG. 3 ). -
FIG. 2 b shows thestator tooth 114 in a front view, andFIG. 2 c shows said stator tooth in a perspective view. -
FIG. 3 a shows a top view of thestator 110 having the annularstator tooth receptacle 112, which has an opening in the center thereof, through which theinlet connecting piece 134 extends (seeFIG. 1 ). Thestator teeth 114, including therecesses 162 thereof, are attached on the periphery of thestator tooth receptacle 112. This can be achieved by therecess 162 and/or thestator tooth receptacle 112 functioning as bonding surfaces in order to bond thestator tooth 114, including therecess 162 thereof, on the edge of thestator tooth receptacle 112.FIG. 3 b shows a corresponding sectional view. -
FIG. 4 a shows a top view of thecontainment shell 116, through theinlet connecting piece 134 of which the fluid can flow in. -
FIG. 4 b shows a sectional view of thecontainment shell 116. As shown inFIG. 4 b, the end of theinlet connecting piece 134 on the air-gap side is designed to accommodate abearing bush 156, as shown inFIG. 4 c. For this purpose, an inner radius R is formed at the end region of theinlet connecting piece 134, into which thebearing bush 156 can be inserted and affixed, for example with the aid of a press fit. - A plain-
bearing element 154 is attached to theextension 152 of the impeller 128 (seeFIG. 1 ) and functions as the counterpart to thebearing bush 156. The plain-bearing element 154 is annular and has anend section 164, the outer diameter of which is reduced such that acircumferential edge 166 is formed externally on the plain-bearing element 154. - The bearing
bush 156 therefore accommodates theend section 164 of the plain-bearing element 154, wherein the inner side of the bearingbush 156 and the outer side of theend section 164 of the plain-bearing element 154 form the sliding surfaces of the plain bearing. Theimpeller 128 is thereby radially supported. The axial degree of freedom of theimpeller 128 is limited by thecircumferential edge 166. - That is, during operation of the axial motor, if the
impeller 128 is drawn in the direction of thestator 110 by the magnetic forces that occur, theedge 166 impacts the front side of the bearingbush 156, thereby forming an abutment for absorbing this magnetic attraction force. Although theimpeller 128 is therefore supported in thecontainment shell 116 such that said impeller has one axial degree of freedom, i.e. axial play, the axial position of theimpeller 128 is defined by the magnetic attraction force during operation of the axial flux motor. - Preferably, at least one of the sliding surfaces of the plain bearing is coated with diamond-like carbon (DLC) and silicon carbide (SiC) or a combination of DLC and SiC, in order to extend the service life of the bearing.
- Embodiments of the invention are particularly advantageous in which the
fluid 108 is suctioned through the bearing, which also contributes to the compact design of the wet rotor pump. The plain bearing can have a very narrow gap, which is approximately 0.01 mm to 0.03 mm, for example, and is therefore also simultaneously very well sealed. - According to an embodiment of the invention, the plain-
bearing element 154 can have one or more radial openings, such as lubrication holes approximately 1 mm in size, for example. By means of these openings, a very small portion of the volume flow of the fluid 108 is directed between the sliding surfaces of the bearing in order to provide additional lubrication of said bearing. This at least one opening is preferably disposed in theend section 164 of the plain-bearing element 154 and is directed toward the center. -
FIG. 5 shows a top view of the rotor having thepermanent magnets 122, which are disposed on thering 124. Thepermanent magnets 122 are preferably formed of samarium cobalt, which has various advantages: - Samarium cobalt can be used in relatively high temperatures without the retentivity being negatively affected thereby; the fluid 108 can have a temperature of up to 200° C., in particular.
- Samarium cobalt has excellent corrosion characteristics and can therefore be exposed to the fluid 108 without coating and without encapsulation.
- Since encapsulation of the
permanent magnets 122 is not required, said permanent magnets can be positioned at a maximum distance away from the rotational axis, thereby ensuring that maximum torque and maximum motor output result for a given amount of magnetic material. - As an alternative, other materials can also be used for the
permanent magnets 122, such as neodymium iron boron. -
FIG. 6 shows thedrive disk 150 in a cross section. Thedrive disk 150 is used to mechanically connect the rotor, i.e. thering 124 having thepermanent magnets 122, to theimpeller 128, wherein theextension 152 of theimpeller 128 extends through thedrive disk 150, as shown inFIG. 1 . -
FIG. 7 shows a sectional view of theimpeller 128.FIG. 8 shows a sectional view of thewet rotor pump 100 in the installed state. - In order to operate the
wet rotor pump 100, the coils of thestator teeth 114 are controlled by thepower electronics 120 such that torque acts on theimpeller 128 via the rotor. The rotor then suctions the fluid 108 through theinlet connecting piece 134 and the bearing such that the fluid 108 is conveyed through thewet rotor pump 100 and exits said wet rotor pump at theoutlet 160. -
FIG. 9 shows a sectional view of a wet rotor pump according to the invention, wherein theimpeller 128 is supported by a combination of a plain bearing and a rolling bearing. In the embodiment shown here, the rolling bearing is designed as a ball bearing. It is also feasible, however, to use other variants of rolling bearings, such as roller bearings, cone bearings, needle roller bearings, or the like. - The rolling bearing is formed by two bearing
shells rolling elements 172. In this case, thelower bearing shell 168 is attached to theimpeller 128, whereas theupper bearing shell 170 is attached to the containment shell. The bearing shells can be bonded, shrunk-fit or pressed onto the corresponding components, or fixedly screwed thereon. The rolling elements are located in the intermediate space between the bearing shells, which said intermediate space is circumscribed by the running surfaces of the bearing shells. If the pump is intended to be operated at high impeller speeds, the rolling bearings can be connected to one another by means of a cage in order to increase the stability of the bearing. - The plain bearing is formed by an upper plain-
bearing surface 174 between theupper bearing shell 170 and the jacket surface of theimpeller 128, and by a lower plain-bearing surface 176 between thelower bearing shell 168 and thecontainment shell 116. The plain bearing has only slight bearing play at thebearing surface 174 in particular, thereby enabling a portion of the fluid 108 to enter the rolling bearing. The penetration of the rolling bearing by the pumped fluid can provide additional lubrication of the rolling bearing. - The bearing play, which can be considered to be an annular opening, is preferably protected by a fine-
strand filter 178, in order to ensure that foreign objects that can be contained in the pumped fluid are kept away from the bearing region. The fine-strand filter 178 is held in position by aclamping ring 180. - Correspondingly precise production can be utilized in order to minimize the bearing play at the plain-bearing surfaces, preferably holding said bearing play in the range below 0.1 mm. This prevents coarse particles that can be contained in the fluid 108 from entering the rolling bearing and damaging the running surfaces of the bearing shells or the rolling bearings. In addition, this narrow hydrodynamic gap functions as a sealing surface between the suction side and the pressure side of the pump, thereby ensuring that leakage effects can be prevented, which said leakage effects typically occur when the impeller is attached to a shaft in a classic manner and is not supported via the suction side.
- In order to further increase the long service life of the bearing, it is possible to coat the running surfaces of the bearing
shells elements 172 and/or the plain-bearingsurfaces -
FIG. 10 shows a further embodiment of awet rotor pump 200 according to the invention. This wet rotor pump differs substantially from the wet rotor pump shown inFIG. 9 by a different geometry and different dimensions of thehousing 204 and themotor cover 216. This is due to the fact that therotor magnets 206 are now no longer attached to the drive disk, but rather are attached directly on theimpeller 202. In order to ensure that the distance between the lower end of thestator teeth 212 and the rotor magnets is still minimal, thestator teeth 212 have been lengthened in the vertical extension thereof. As a result, thecontainment shell 222, including thesuction connecting piece 218, has a different shape. Thestator tooth receptacle 214 is unchanged compared to the stator tooth receptacle of the wet rotor pump shown inFIG. 9 . - A further difference between the
wet rotor pump 200 and the wet rotor pump described with reference toFIG. 9 relates to the support of theimpeller 202 in thecontainment shell 222. Instead of a rolling bearing comprising the bearingshells elements 172, theimpeller 202 of thewet rotor pump 200 is supported in the axial direction by two magnetic rings, which are magnetized such that, in the installed state, said magnetic rings repel one another in the axial direction. In this case, a lowermagnetic ring 208 is attached to theimpeller 202, whereas an uppermagnetic ring 210 is attached to the containment shell. As is the case for the bearingshells FIG. 9 , the magnetic rings can be attached by means of bonding, screwing, shrink-fitting, press-fitting, or other attachment methods. - The
magnetic rings - The thickness of the encapsulation can be between 1 mm and 2 mm, for example. The
magnetic ring 208, which is pressed on on the impeller side, is manufactured in a manner similar to that of thelower bearing shell 168 of the wet rotor pump shown inFIG. 9 such that a hydrodynamic gap forms between the outer jacket surface of themagnetic ring 208 and the inner jacket surface of thecontainment shell 222, which said hydrodynamic gap also functions as a sealing gap. - The
magnetic rings magnetic rings wet rotor pump 200, equilibrium sets in between the attractive force between therotor magnets 206 and thestator teeth 212 and the repulsive force between themagnetic rings stator teeth 212 and therotor magnets 206, while an air gap having a width of 3 mm forms between themagnetic rings magnetic rings rotor magnets 206 and thestator teeth 212. - As the speed and, therefore, the output of the
wet rotor pump 200 increases, the pressure differential between the suction side and the pressure side of thewet rotor pump 200 and, therefore, the contact pressure of theimpeller 202 increases upwardly, in the direction toward thesuction connecting piece 218. Similarly, the contact pressure on the mutually repellentmagnetic rings magnetic rings rotor magnets 206 and the stator teeth 12 is reduced. The reduction of the air gaps continues until a new equilibrium has set in between the contact pressure, the attractive force between therotor magnets 206 and thestator teeth 212, and the repulsive force between themagnetic rings - In order to prevent the rotor from being set down onto static components of the
wet rotor pump 200, the performance limit of the wet rotor pump can be dimensioned such that the air gap between therotor magnets 206 and thestator teeth 212 does not fall below a width of 0.2 mm. In addition,safety sliding surfaces 220 can be mounted on the rotor, which extend upwardly beyond therotor magnets 206 by 0.2 mm, for example. In the event that the aforementioned performance limit is exceeded, said safety sliding surfaces can support the rotor at thecontainment shell 222 and prevent damage to theimpeller 202 or therotor magnets 206. - Given that the air gap between the
rotor magnets 206 and thestator teeth 212 is reduced as the pressure output increases, the coupling between therotor magnets 206 and thestator teeth 212 increases due to the increasing magnetic flux density. This effectively results in an increase in output and, therefore, to increased efficiency of thewet rotor pump 200. -
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- 100 wet rotor pump
- 102 motor cover
- 104 end face
- 106 opening
- 108 fluid
- 110 stator
- 112 stator tooth receptacle
- 114 stator tooth
- 116 containment shell
- 118 receiving region
- 120 power electronics
- 122 permanent magnet
- 124 ring
- 126 end
- 128 impeller
- 130 disk
- 132 recess
- 134 inlet connecting piece
- 136 printed circuit board
- 138 attachment region
- 140 hole
- 142 housing half
- 144 housing half
- 146 opening
- 148 attachment region
- 150 drive disk
- 152 extension
- 153 screw
- 154 plain-bearing element
- 156 bearing bush
- 158 screw
- 160 outlet
- 162 recess
- 164 end section
- 166 edge
- 168 lower bearing shell
- 170 upper bearing shell
- 172 rolling element
- 174 upper plain-bearing surface
- 176 lower plain-bearing surface
- 178 fine-strand filter
- 180 clamping ring
- 200 wet rotor pump
- 202 impeller
- 204 pump housing
- 206 rotor magnets
- 208 lower magnetic ring
- 210 upper magnetic ring
- 212 stator tooth
- 214 stator tooth receptacle
- 216 motor cover
- 218 suction connecting piece
- 220 safety sliding surface
- 222 containment shell
Claims (28)
1. A wet rotor pump comprising an axial flux motor having a stator, a containment shell, and a rotor, wherein the stator and the containment shell are disposed in a dry zone and the rotor on an impeller is disposed in a wet zone, comprising an inlet line for a fluid to be pumped by the impeller, and a bearing for the impeller, wherein the bearing is disposed at one end of the inlet line and supports the impeller such that said impeller has one axial degree of freedom, wherein the inlet line extends through the stator, the containment shell, and the bearing in the axial direction, wherein the stator is formed by an annular stator tooth receptacle, along the periphery of which stator teeth are attached.
2. The wet rotor pump according to claim 1 , wherein the inlet line is formed at least by an inlet connecting piece embodied on the containment shell, and by the bearing.
3. The wet rotor pump according to claim 1 , wherein the containment shell comprises a disk, which extends into the air gap of the axial flux motor, and the containment shell is designed as a single piece, in particular as a molded part.
4. (canceled)
5. (canceled)
6. (canceled)
7. The wet rotor pump according to claim 1 , wherein each of the stator teeth comprises a receiving region for a coil, which said receiving region extends in the axial direction and is limited by an air-gap side end of the particular stator tooth, wherein the air-gap side end of the stator tooth has an end face, which is greater than the cross section of the receiving region.
8. The wet rotor pump according to claim 1 , comprising power electronics for controlling the stator, wherein the power electronics are disposed in the interior of the space circumscribed between the stator and the containment shell.
9. The wet rotor pump according to claim 1 , wherein the containment shell comprises a disk, which extends into the air gap of the axial flux motor, wherein the disk has a central opening, on which an inlet connecting piece for the inflow of the fluid is formed, wherein an end region of the inlet connecting piece accommodates the bearing.
10. The wet rotor pump according to claim 1 , wherein the bearing is a plain bearing, which is designed to radially support the impeller and to axially support the impeller on one side as an abutment for the magnetic attraction force exerted by the stator onto the impeller.
11. The wet rotor pump according to claim 10 , wherein the bearing is formed, on the containment-shell side, by a bearing bush disposed in the end region of the inlet connecting piece and, on the impeller side, by a plain-bearing element, which has a sliding surface, which engages into the bearing bush.
12. The wet rotor pump according to claim 11 , wherein the plain-bearing element has a circumferential edge, which is disposed so as to form a stop at the bearing bush when a magnetic attraction force from the stator acts on the rotor in the axial direction.
13. The wet rotor pump according to claim 12 , wherein the plain-bearing element comprises one or more openings, which extend in the radial direction and are designed such that, during operation, a portion of the fluid flow is directed between the sliding surface of the plain-bearing element and the sliding surface of the bearing bush.
14. (canceled)
15. (canceled)
16. (canceled)
17. (canceled)
18. (canceled)
19. The wet rotor pump according to claim 1 , wherein the bearing is a combination of a plain bearing and a magnetic bearing, which are designed to provide radial and axial support of the impeller, wherein the magnetic bearing functions as an abutment in the axial direction for the magnetic attraction force exerted by the stator onto the impeller, and the plain bearing supports the rotor in the radial direction.
20. The wet rotor pump according to claim 19 , wherein the magnetic bearing is formed by magnetic rings, wherein a first magnetic ring is attached to the impeller and a second magnetic ring is attached to the containment shell, and the magnetization of the magnetic rings is configured such that said magnetic rings repel one another in the axial direction in the installed state in the wet rotor pump.
21. The wet rotor pump according to claim 20 , wherein the plain bearing is formed, on the impeller side, by the outer jacket surface of the first magnetic ring and the jacket surface of the containment shell and, on the containment-shell side, by the inner jacket surface of the second magnetic ring and the jacket surface of the impeller.
22. The wet rotor pump according to claim 19 , wherein the jacket surfaces of the magnetic rings are coated with silicon carbide (SiC) and/or diamond-like carbon (DLC) and/or silicon-doped DLC.
23. The wet rotor pump according to claim 19 , wherein the bearing is protected by a fine-strand filter against particles entering the bearing.
24. The wet rotor pump according to claim 9 , wherein the disk of the containment shell has recesses, along the periphery thereof, for accommodating the air-gap side ends of the stator teeth.
25. The wet rotor pump according to claim 1 , wherein the rotor contains samarium cobalt (SmCo).
26. The wet rotor pump according to claim 1 , wherein the rotor is formed by a plurality of permanent magnets disposed on the periphery of the impeller, or by a magnetic ring having multipolar magnetization.
27. The wet rotor pump according to claim 1 , wherein a seal is formed by the bearing.
28. The wet rotor pump according to claim 1 , wherein the permanent magnets are shorter in the radial direction than the ends of the stator teeth.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102012200803.9A DE102012200803B4 (en) | 2012-01-20 | 2012-01-20 | Wet rotor |
DE102012200803.9 | 2012-01-20 | ||
PCT/EP2013/050816 WO2013107807A2 (en) | 2012-01-20 | 2013-01-17 | Wet rotor pump |
Publications (1)
Publication Number | Publication Date |
---|---|
US20140341764A1 true US20140341764A1 (en) | 2014-11-20 |
Family
ID=47594737
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/373,205 Abandoned US20140341764A1 (en) | 2012-01-20 | 2013-01-17 | Wet rotor pump |
Country Status (3)
Country | Link |
---|---|
US (1) | US20140341764A1 (en) |
DE (1) | DE102012200803B4 (en) |
WO (1) | WO2013107807A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20200116151A1 (en) * | 2018-10-15 | 2020-04-16 | Coavis | Impeller for electric water pump |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3904393A (en) * | 1973-07-13 | 1975-09-09 | Raymond A Morse | Venturi-type water aerator |
US5149253A (en) * | 1989-06-05 | 1992-09-22 | Ebara Corporation | Magnet pumps |
US6663827B2 (en) * | 2001-04-13 | 2003-12-16 | Romain L. Billiet | Rare earth magnet rotors for watch movements and method of fabrication thereof |
US20090060408A1 (en) * | 2005-03-02 | 2009-03-05 | Ebara Corporation | Diamond-coated bearing or seal structure and fluid machine comprising the same |
US20100158724A1 (en) * | 2008-12-19 | 2010-06-24 | Olai Ihle | Electrically commutated DC motor for a liquid pump |
US20110144744A1 (en) * | 2009-12-03 | 2011-06-16 | Richard Wampler | Total artificial heart |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1613626A1 (en) * | 1967-03-09 | 1970-05-14 | Eberspaecher J | Electric motor |
US4880362A (en) * | 1988-05-24 | 1989-11-14 | Laing Karsten A | Rotor with stabilizing magnets |
JP2989233B2 (en) * | 1990-07-31 | 1999-12-13 | エヌティエヌ株式会社 | Turbo type pump |
US5332374A (en) * | 1992-12-30 | 1994-07-26 | Ralph Kricker | Axially coupled flat magnetic pump |
FR2787527B1 (en) * | 1998-12-22 | 2001-03-09 | Jeumont Ind | MOTORIZED DEVICE WITH CENTRIFUGAL FLUID CIRCULATION, SUCH AS A MOTOR PUMP OR A MOTOR COMPRESSOR |
DE10009376A1 (en) * | 2000-02-29 | 2001-08-30 | Wilo Gmbh | Motor-driven pump has wet rotor between suction port and impeller wheel with central suction opening enclosed by hollow cylindrical shaft carrying rotor's permanent magnets |
DE10053400A1 (en) * | 2000-10-21 | 2002-05-02 | Daimler Chrysler Ag | Axial flow motor for concentrating flow with permanent magnet excitation has a stator and a rotor with flow concentration pieces of soft magnetic material and permanent magnets magnetized at a tangent to the direction of movement. |
AT414064B (en) * | 2001-05-11 | 2006-08-15 | Tcg Unitech Ag | PUMP FOR LIQUID MEDIA |
DE10203778A1 (en) * | 2002-01-30 | 2003-07-31 | Siemens Ag | Electrically driven pump, e.g. for motor vehicles, has electric motor in form of disk rotor with magnetic ring mounted on pump wheel in region through which fluid flows |
DE10303778B4 (en) * | 2003-01-31 | 2008-04-10 | Daimler Ag | Actuating arrangement for opening and closing a vehicle wing |
DE102005015213A1 (en) * | 2005-04-02 | 2006-10-05 | Pierburg Gmbh | Wet running pump for use as cooling water pump in motor vehicles has stators that are connected to printed circuit board (PCB) that separates wet and dry areas |
JP4517076B2 (en) * | 2005-06-23 | 2010-08-04 | 独立行政法人産業技術総合研究所 | Artificial heart pump with hydrodynamic bearing |
JP5318730B2 (en) * | 2009-11-17 | 2013-10-16 | 株式会社荏原製作所 | Motor pump |
-
2012
- 2012-01-20 DE DE102012200803.9A patent/DE102012200803B4/en not_active Expired - Fee Related
-
2013
- 2013-01-17 US US14/373,205 patent/US20140341764A1/en not_active Abandoned
- 2013-01-17 WO PCT/EP2013/050816 patent/WO2013107807A2/en active Application Filing
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3904393A (en) * | 1973-07-13 | 1975-09-09 | Raymond A Morse | Venturi-type water aerator |
US5149253A (en) * | 1989-06-05 | 1992-09-22 | Ebara Corporation | Magnet pumps |
US6663827B2 (en) * | 2001-04-13 | 2003-12-16 | Romain L. Billiet | Rare earth magnet rotors for watch movements and method of fabrication thereof |
US20090060408A1 (en) * | 2005-03-02 | 2009-03-05 | Ebara Corporation | Diamond-coated bearing or seal structure and fluid machine comprising the same |
US20100158724A1 (en) * | 2008-12-19 | 2010-06-24 | Olai Ihle | Electrically commutated DC motor for a liquid pump |
US20110144744A1 (en) * | 2009-12-03 | 2011-06-16 | Richard Wampler | Total artificial heart |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20200116151A1 (en) * | 2018-10-15 | 2020-04-16 | Coavis | Impeller for electric water pump |
US11873819B2 (en) * | 2018-10-15 | 2024-01-16 | Coavis | Impeller for electric water pump |
Also Published As
Publication number | Publication date |
---|---|
WO2013107807A2 (en) | 2013-07-25 |
DE102012200803A1 (en) | 2013-07-25 |
DE102012200803B4 (en) | 2015-04-02 |
WO2013107807A3 (en) | 2013-10-03 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: YASA MOTORS POLAND SP. Z.O.O., POLAND Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MULLER, MARKUS;REEL/FRAME:034099/0295 Effective date: 20141027 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |