U.S. patent application number 11/576688 was filed with the patent office on 2009-01-22 for arrangement for delivering fluids.
This patent application is currently assigned to EBM-PAPST ST. GEORGEN GmbH & Co. KG. Invention is credited to Michael Burgert, Alexander Jordan.
Application Number | 20090022607 11/576688 |
Document ID | / |
Family ID | 35285409 |
Filed Date | 2009-01-22 |
United States Patent
Application |
20090022607 |
Kind Code |
A1 |
Jordan; Alexander ; et
al. |
January 22, 2009 |
ARRANGEMENT FOR DELIVERING FLUIDS
Abstract
An arrangement for delivering fluids has a fluid pump having a
pump wheel (90), which wheel is joined to a first permanent magnet
(92). The pump wheel (90) is rotatably arranged inside a
liquid-tight pump housing (80, 82, 84, 86, 88). This housing is
shaped, near the first permanent magnet (92), as a partitioning can
(80, 82). The arrangement also has an electronically commutated
electric motor (20) having a stator (22) and a rotor (26) arranged
rotatably relative thereto, which rotor comprises a second
permanent magnet (67) that coacts with the first permanent magnet
(92) to act as a magnetic coupling (94). Arranged in the space
between the second permanent magnet (67) and partitioning can (80,
82) is a plurality of soft ferromagnetic magnetic flux conductors
(150).
Inventors: |
Jordan; Alexander;
(Pfalzrafenweiler, DE) ; Burgert; Michael;
(Freiburg, DE) |
Correspondence
Address: |
WARE FRESSOLA VAN DER SLUYS & ADOLPHSON, LLP
BRADFORD GREEN, BUILDING 5, 755 MAIN STREET, P O BOX 224
MONROE
CT
06468
US
|
Assignee: |
EBM-PAPST ST. GEORGEN GmbH &
Co. KG
|
Family ID: |
35285409 |
Appl. No.: |
11/576688 |
Filed: |
August 10, 2005 |
PCT Filed: |
August 10, 2005 |
PCT NO: |
PCT/EP05/08668 |
371 Date: |
April 11, 2007 |
Current U.S.
Class: |
417/420 |
Current CPC
Class: |
F04D 25/062 20130101;
F04D 25/16 20130101; F04D 13/12 20130101; F04D 25/0646 20130101;
F04D 13/027 20130101; F04D 29/059 20130101; F04D 25/064 20130101;
F04D 13/026 20130101 |
Class at
Publication: |
417/420 |
International
Class: |
F04D 13/02 20060101
F04D013/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 6, 2004 |
DE |
20 2004 015 648.2 |
Claims
1. An arrangement for pumping fluids, which comprises: a fluid pump
having a pump wheel (90), which wheel is joined to a first
permanent magnet (92), which pump wheel (90) is rotatably arranged
inside a liquid-tight pump housing (80, 82, 84, 86, 88), which
housing (80, 82, 84, 86, 88) is implemented, adjacent said first
permanent magnet (92), as a partitioning can (80, 82); an
electronically commutated electric motor (20) having a stator (22)
and a rotor (26) arranged rotatably relative thereto, which rotor
comprises a second permanent magnet (67) that coacts with the first
permanent magnet (92) to act as a magnetic coupling (94); and a
plurality of soft ferromagnetic magnetic flux conductors (150;
150'; 150'') arranged in the space between the second permanent
magnet (67) and the partitioning can (80, 82), which conductors are
arranged at a distance from one another in such a way that they map
the magnetic field of the second permanent magnet (67), which field
is effective at their end facing away from the partitioning can
(80, 82), onto a region of the partitioning can (80, 82) associated
with the first permanent magnet (92).
2. The arrangement according to claim 1, wherein the soft
ferromagnetic magnetic flux conductors (150; 150'; 150'') are
implemented as elements made of soft ferromagnetic material, which
are arranged in a star configuration around the partitioning can
(80, 82).
3. The arrangement according to claim 2, wherein the elements (150;
150'; 150'') are implemented in substantially plate-shaped fashion
from soft ferromagnetic material.
4. The arrangement according to claim 1, wherein the soft
ferromagnetic magnetic flux conductors (150; 150'; 150'') are
implemented in the manner of flux concentrators.
5. The arrangement according to claim 1, wherein the electronically
commutated electric motor is implemented as an external-rotor motor
(20) having a rotor cup (63), inside which cup are arranged the
rotor magnet (36) of the motor (20) and the second permanent magnet
(67).
6. The arrangement according to claim 1, wherein a bearing element
(106) for the pump wheel (90) is arranged inside the partitioning
can (80, 82) on the latter, and a bearing element (30) for the
rotor (26) of the electronically commutated electric motor (20) is
arranged outside the partitioning can (80, 82) on the latter.
7. The arrangement according to claim 6, wherein the bearing
element for the rotor (26) of the electric motor (20) comprises a
bearing tube (30) that is fixedly connected to the partitioning can
(80, 82).
8. The arrangement according to claim 7, wherein the bearing tube
(30) is integrally formed with the partitioning can (80, 82).
9. The arrangement according to claim 1, wherein fan blades (64)
are joined to the rotor (26) of the electric motor (20).
10. The arrangement according to claim 9, wherein the permanent
magnet of the rotor comprises a yoke that is implemented as a
cup-like part (40), and the fan blades (64) are arranged on this
cup-like part (40).
11. The arrangement according to claim 9, wherein the fan blades
(64) are implemented as part of an axial fan wheel.
12. The arrangement according to claim 9, wherein the fan blades
are implemented as part of a diagonal fan wheel.
13. The arrangement according to claim 9, wherein the fan blades
are implemented as part of a radial fan wheel.
14. The arrangement according to claim 1, further comprising an
air-directing housing (68) is joined to the partitioning can (80,
82).
15. The arrangement according to claim 14, wherein the
air-directing housing (68) is implemented as a plastic part
integral with the partitioning can (80, 82).
16. The arrangement according to claim 15, wherein the partitioning
can (80, 82) is joined to the air-directing housing (68) via at
least one strut (114).
17. The arrangement according to claim 7, wherein the electric
motor is implemented as an external-rotor motor (20); and the
internal stator (92) of said motor is mounted on the bearing tube
(30), which tube serves for journaling of the rotor (26).
18. The arrangement according to claim 1, wherein the soft
ferromagnetic magnetic flux conductors (150; 150'; 150'') are
joined at their radially inner end regions to a support part (160)
made of non-ferromagnetic material.
19. The arrangement according to claim 18, wherein the support part
(160) is arranged on the partitioning can (80, 82).
20. The arrangement according to claim 19, wherein the partitioning
can (80, 82) has an approximately cylindrical periphery; and the
support part (160) is arranged on said periphery.
21. The arrangement according to claim 18, wherein the support part
(160) is formed of plastic material, and is equipped with axial
projections (168; 174) that are joined by means of a welding
operation to an adjacent plastic part of the arrangement.
22. The arrangement according to claim 21, wherein the welded join
is implemented by ultrasonic welding (170) at one axial end of the
support part (160).
23. The arrangement according to claim 1, wherein the cross section
of soft ferromagnetic magnetic flux conductors (150'') inside the
support part (160) is enlarged (180), at least locally, in order to
produce good anchoring of said conductors (150'') in the support
part.
Description
CROSS-REFERENCE
[0001] This application is a section 371 of PCT/EP05/08668, filed
10 Aug. 2005 and published 13 Apr. 2006 as WO 2006-37396-A.
FIELD OF THE INVENTION
[0002] The invention relates to an arrangement for pumping fluids.
As fluids, liquid and/or gaseous media can be pumped.
BACKGROUND
[0003] In computers, components having high heat flux densities
(e.g. 60 W/cm.sup.2) are in use today. The heat from these
components must first be transferred into a liquid circulation
system, and from that circulation system the heat must be
discharged to the ambient air via a liquid/air heat exchanger.
[0004] Dissipation of heat from components having a high heat flux
density is accomplished by means of so-called heat absorbers or
cold plates. In these, heat is transferred to a cooling liquid, and
the latter is usually caused to circulate in a circulation
system.
[0005] In this context, the cooling liquid flows not only through
the heat absorber but also through a liquid pump that produces the
forced circulation and produces an appropriate pressure buildup and
appropriate volumetric flow through the heat absorber and an
associated heat exchanger, so that the heat transfer coefficients
relevant to these heat-transfer elements become large and the
temperature gradients necessary for heat transfer become small.
[0006] A fan is usually arranged near the heat exchanger, which fan
produces, on the air side of the heat exchanger, a forced
convection of the cooling air as well as good transfer
coefficients.
[0007] In cooling arrangements of this kind, the fan and the liquid
pump are driven separately, and these components are also often
physically separate from one another. Two drives are therefore
required, which in most cases operate rotationally. These drives
require energy and also a fairly large installation space, both of
which are undesirable.
SUMMARY OF THE INVENTION
[0008] It is therefore an object of the invention to make available
a novel arrangement for delivering fluids.
[0009] According to the invention, this object is achieved by using
soft ferromagnetic flux conductors to assist in magnetically
coupling an electric motor to a pump rotor across a partitioning
can which separates them.
[0010] A very compact arrangement with good efficiency is thereby
obtained, in which context the soft ferromagnetic magnetic flux
conductors bridge the space between the partitioning can and the
second permanent magnet and thereby make possible a greater
distance between the first permanent magnet and second permanent
magnet of the magnetic coupling.
BRIEF FIGURE DESCRIPTION
[0011] Further details and advantageous refinements of the
invention will be evident from the exemplifying embodiments, in no
way to be understood as a limitation of the invention, that are
described below and depicted in the drawings.
[0012] FIG. 1 is a longitudinal section through a preferred
embodiment of the invention, looking along line I-I of FIG. 5;
[0013] FIGS. 2 and 3 are exploded views of the arrangement
according to FIG. 1;
[0014] FIG. 4 is a schematic view to explain the invention;
[0015] FIG. 5 is a section looking along line V-V of FIG. 1;
[0016] FIG. 6 is a three-dimensional view of an arrangement having
flux-conducting plates, according to a variant of the
invention;
[0017] FIG. 7 is an enlarged view of a portion of FIG. 6, showing
projections that are deformed upon ultrasonic welding and thereby
create a local welded join;
[0018] FIG. 8 is a plan view from below of the arrangement of FIG.
6, looking in the direction of arrow VIII of FIG. 6;
[0019] FIG. 9 is a plan view from above of the arrangement of FIG.
6, looking in the direction of arrow IX of FIG. 6;
[0020] FIG. 10 schematically depicts how the arrangement according
to FIG. 6 is mounted by being pressed on and ultrasonically
welded;
[0021] FIG. 11 is an enlargement of a detail;
[0022] FIG. 12 shows the arrangement according to FIG. 10 after its
assembly;
[0023] FIG. 13 is a three-dimensional view of an arrangement having
flux-conducting plates, according to a further variant of the
invention;
[0024] FIG. 14 is an enlarged view of a portion of FIG. 13;
[0025] FIG. 15 is a horizontal section through the arrangement
according to FIG. 13;
[0026] FIG. 16 shows a detail of FIG. 15;
[0027] FIG. 17 is a section through a flux-conducting plate of FIG.
13; and
[0028] FIGS. 18 and 19 are two schematic views to explain assembly
of the rotor and its bearings in the context of the arrangement
according to FIGS. 1 to 3.
DETAILED DESCRIPTION
[0029] In the description that follows, the terms "left," "right,"
"top," and "bottom" refer to the respective Figure of the drawings.
Identical or identically functioning parts are labeled in the
various Figures with the same reference characters, with an
apostrophe added if applicable, e.g. 150 and 150'.
[0030] FIG. 1 is an enlarged depiction of an arrangement having an
electronically commutated external-rotor motor 20. The latter has
an internal stator 22 of conventional design as depicted by way of
example in section in FIG. 2, e.g. a stator having salient poles or
a claw pole stator, and the latter is separated by a substantially
cylindrical air gap 24 from a permanent-magnet external rotor 26
whose construction is likewise particularly easy to see in FIG. 2.
External rotor 26 rotates around internal stator 22 during
operation, and such motors 20 are therefore referred to as
external-rotor motors.
[0031] Internal stator 22 is mounted, usually by being pressed on,
on a bearing tube 30 made of a suitable plastic. The shape of
bearing tube 30 is particularly clearly evident from FIGS. 2 and 3.
Located to the right of internal stator 22 in FIG. 1 is a circuit
board 32. Located on the latter are, for example, electronic
components (not depicted here) that are necessary for electronic
commutation of motor 20, as well as a rotor position sensor 34 that
is controlled by a permanent ring magnet 36 of external rotor 26.
Ring magnet 36 is radially magnetized and preferably has four rotor
poles. Its magnetization, i.e. the distribution of its magnetic
flux density, can be e.g. rectangular or trapezoidal. Sensor 34 is
controlled by a leakage field of ring magnet 36, enabling
non-contact sensing of the position of rotor 26.
[0032] External rotor 26 has a design with a so-called rotor cup
40, which is implemented here as a deep-drawn cup-shaped
sheet-metal part made of soft ferromagnetic material. Ring magnet
36 is mounted in this sheet-metal part 40 so that the latter forms
a magnetic yoke for rotor magnet 36.
[0033] Sheet-metal part 40 is mounted on a hub 44 in which a shaft
46 is mounted in the manner depicted. Shaft 46 is journaled in two
ball bearings 48, 50 whose outer rings are held at a distance from
one another by a spacing element 52 (cf. the schematic depictions
in FIGS. 18 and 19). Upon assembly, these ball bearings 48, 50,
together with shaft 46, are pressed from the left in FIG. 1 into
bearing tube 30 and are retained there by a latching member 54 (cf.
FIGS. 18 and 19). An axial projection 56 of flange part 44 serves
for pressing in latching member 54. Located between said flange
part and the inner ring of rolling bearing 48 is a compression
spring 58 that, after installation, presses rotor 26 to the left
(with reference to FIG. 1) until a snap ring 59 mounted at the
right end of shaft 46 abuts against the inner ring of rolling
bearing 50. With this assembly procedure, shaft 46 is therefore
displaceable in the inner rings of the two rolling bearings 48, 50.
This assembly procedure of course represents only one preferred
embodiment. Many other procedures are possible.
[0034] This assembly procedure makes it possible, in the context of
FIG. 1, to install rotor 26, together with its already
pre-installed bearings 48, 50, into bearing tube 30 from the left,
so that the right end 60 (in FIG. 1) of the internal opening of
bearing tube 30 can be closed off in liquid-tight fashion as
depicted. This assembly procedure will be explained in further
detail with reference to FIGS. 18 and 19 below.
[0035] The outer side of sheet-metal part 40 is surrounded by a
plastic part 63 in which fan blades 64 are formed, in the manner
depicted, by plastic injection molding. These blades rotate, during
operation, in an opening 66 of a fan housing 68 (cf. FIG. 3). Fan
housing 68 preferably has the usual square outline of an equipment
fan, and has an attachment hole 70 at each of its corners. Plastic
part 63 has, at the right in FIG. 1, a continuation part 65 in
which is mounted a permanent magnet 67 that is part of a magnetic
coupling.
[0036] Bearing tube 30 transitions to the right in FIG. 1 into a
flange-like portion 80, which proceeds perpendicular to rotation
axis 81 of rotor 26 and transitions at its periphery into a
cylindrical portion 82 that here has the function of a so-called
partitioning can and is therefore referred to hereinafter as
partitioning tube 82. The latter transitions via a shoulder 84 into
a cylindrical portion 86 whose free end, as depicted, serves for
mounting of a cover 88, for example by laser welding. An inflow
fitting 96 for cooling liquid is provided on cover 88. A pump wheel
90 is rotatably arranged in the housing part that is closed off by
cover 88. Bearing tube 83 is, as depicted, preferably manufactured
integrally with parts 82, 84, 86 from a magnetically transparent
plastic.
[0037] Pump wheel 90 is preferably implemented integrally with a
permanent-magnet rotor 92 that, with permanent magnet 67, forms a
magnetic coupling 94; i.e., when permanent magnet 67 rotates,
permanent magnet 92 also rotates and thereby drives delivery wheel
90, with the result that the latter draws in liquid via inlet 96
and pumps it out via an outlet 98, as indicated by arrows. Any
desired other hydraulic machine, e.g. a compressor for a
refrigerant, can of course also be provided instead of a spiral
pump.
[0038] As is apparent from the drawings, the distance from
permanent magnet 67 to permanent magnet 92 is large, so that a
direct transfer of torque between these two magnets would not be
possible. For this reason, a plurality of magnetic flux conductors
in the form of flux-conducting elements 150 is arranged between
magnets 67, 92, which elements map the magnetic field of the
rotating permanent magnet 67 onto partitioning tube 82 and thereby
produce a rotation of permanent magnet 92.
[0039] FIG. 2 is a perspective depiction of approximately half of
the flux-conducting elements 150, and FIG. 4 explains their manner
of operation. Flux-conducting elements 150 have, in FIGS. 1 and 2,
the shape of pentagonal panels made of dynamo sheet, i.e. soft
ferromagnetic material. In the exemplifying embodiment according to
FIGS. 1 to 5, they are embedded with their radially inner ends in
partitioning tube 82 (cf. FIG. 5), and proceeding from there they
become wider in the radially outward direction. They are arranged
in a star shape, e.g. in the shape according to FIG. 5. Their outer
ends 152 are separated from permanent magnet 67 by a magnetic air
gap 154. ("Magnetic air gap" is an electrical-engineering term. A
plastic that is magnetically transparent can also form an "air gap"
of this kind, i.e. in magnetic terms it acts like air.)
[0040] FIG. 4 shows an instantaneous rotational position of magnet
67, which is depicted as having four poles, as is magnet 92. The
latter is depicted in simplified fashion. In this position, a pole
boundary 156 located between two adjacent poles of magnet 67 is
shown at approximately the 12:30 position with reference to a clock
dial. To the left of boundary 156, flux-conducting elements 150 are
located opposite south poles S; to the right of boundary 156,
however, they are located opposite north poles N. Flux-conducting
elements 150 each extend here in radial planes and at a distance
from one another, with the result that they are magnetically
insulated from one another. They are preferably distributed
regularly over the circumference, in order to prevent the creation
of reluctance torques and preferred magnetic positions.
[0041] Accordingly, south poles S are also constituted at the inner
end (viewed radially) of flux-conducting elements 150 to the left
of pole boundary 156, which poles attract the north pole N of
permanent magnet 92.
[0042] To the right of pole boundary 156, flux-conducting elements
150 are located opposite north poles N, and north poles N that
attract a south pole of permanent magnet 92 are accordingly located
at the radially inner ends of flux-conducting elements 150
there.
[0043] When external magnet 67 rotates clockwise, as depicted in
FIG. 5, the poles on the inner ends of flux-conducting elements 150
thus also move and consequently produce a rotation of the inner
permanent magnet 92 at the same speed. The arrangement according to
FIG. 4 thus works on the principle of a synchronous motor.
(Alternatively, in special cases, operation with slippage is also
not precluded; this requires the use of particular materials in
magnetic coupling 94, as known to one skilled in the art.)
[0044] Flux-conducting elements 150 therefore bridge the distance
between magnets 67 and 92, so that magnet 92 can have a small
diameter. This is important because magnet 92 rotates in the
cooling liquid, and consequently, if the diameter of magnet 92 is
small, the frictional losses produced in that cooling liquid are
low. This contributes to good efficiency for the arrangement.
[0045] Permanent magnet 92 of the fluid pump is rotatably journaled
by means of a plain bearing 100 on a stationary shaft 106 that is
mounted in liquid-tight fashion, in the manner depicted, in a
rightward-protruding projection 107 of portion 80. A snap ring (not
depicted) can be provided at the right end of shaft 106. Magnet 92
is attracted by the adjacent flux-conducting elements 150 and
retained in the axial position depicted.
[0046] For the mounting procedure depicted for bearings 48, 50, an
open space 109 is required between the right end (in FIG. 1) of
shaft 46 and the bottom of opening 60. Despite this open space 109,
the configuration with projection 107 enables an axially compact
design.
[0047] Cylindrical portion 86 is joined via radially extending
struts 114 to fan housing 68, so that the latter, with partitioning
tube 82, portion 80, and bearing tube 30, forms a one-piece plastic
part; this simplifies assembly of the arrangement, minimizes the
number of parts, and reliably separates from one another the units
being used, so that liquid cannot travel from hydraulic machine 90
to electric motor 20 and damage it. Stationary shaft 106 likewise
forms a constituent of this injection-molded part, since it is
anchored therein during manufacture, and therefore likewise
contributes to the compact design.
Manner of Operation
[0048] In operation, external-rotor motor 20 drives external rotor
26 so that fan blades 64 rotate in housing 68 and thereby generate
an air flow therein. Alternatively, the fan can also be implemented
as a diagonal or radial fan. An axial fan is depicted.
[0049] At the same time, ring magnet 67 drives rotor magnet 92 via
flux-conducting elements 150 and through partitioning tube 82, thus
rotating pump wheel 90 so that the latter draws in liquid through
inlet 96 and pumps it out through outlet 98. A pump of this kind
can be used, for example, in a fountain in order to draw in water
and pump it out, or to pump blood in a heart-lung machine, or to
transport cooling liquid in a closed cooling circuit, in which case
pump wheel 90 then has the function of a circulating pump.
[0050] Because cover 88 is joined in liquid-tight fashion to
cylindrical part 86, e.g. by laser welding, no liquid can escape to
the outside from housing 88. Contributing to this is the fact that
portion 80 and its projection 107 are free of any kind of orifices.
This is possible because rotor 26 is very easy to install, for
example, in the manner described below in the context of FIGS. 18
and 19, and it is not necessary to have access to the right end (in
FIG. 1) of shaft 46 during installation. Pump wheel 90 of the
centrifugal pump with its plain bearing 100 can likewise be
installed from the right in FIG. 1 onto stationary shaft 106 before
cover 88 is mounted. The result of flux-conducting elements 150 is
that rotor 26, including its axial extension 65 and permanent
magnet 67, can very easily be pushed during installation by way of
said flux-conducting elements 150, without requiring any complex
installation operations for the purpose. The entire remaining
portion of the arrangement can be preassembled prior to the
installation of rotor 26, since because of flux-conducting elements
150 it is possible to make the outside diameter in the region of
these elements 150 larger than the outside diameter of internal
stator 22 and circuit board 32.
[0051] As an alternative to FIG. 1, it is possible to provide for
the journaling of pump wheel 90 a rotating shaft that is journaled,
just like shaft 46 of motor 20, in a bearing tube (not depicted)
that, like bearing tube 30, is then implemented integrally with
portion 80 and protrudes therefrom to the right, i.e. in
mirror-image fashion to bearing tube 30.
[0052] According to FIG. 18, which differs slightly from what is
depicted in FIGS. 1 to 5, various components are preinstalled on
shaft 46 before motor 20 is assembled.
[0053] Beginning at projection 56, the first is compression spring
58, whose larger-diameter end rests in a depression 39. This spring
is followed by the annular retaining member in the form of
retaining washer 54. Spring 58 does not abut against retaining
member 54.
[0054] Retaining member 54 is followed by rolling bearing 48, with
its outer ring 48e and its inner ring 48i. The latter is
displaceable in an axial direction on shaft 46. The lower end of
spring 58 abuts against the upper end of inner ring 48i. Rolling
bearing 48 is followed by spacing element 52, which is guided
displaceably on shaft 46 by means of a radially inwardly protruding
projection 53, and whose upper end, as depicted, abuts against the
lower end of outer ring 48e.
[0055] Spacing element 52 is followed by lower rolling bearing 50,
with its outer ring 50e that abuts with its upper end against
spacing element 52, and with its inner ring 50i that is axially
displaceable on shaft 46 and abuts with its lower end against snap
ring 59 when the assembling of motor 20 is finished.
[0056] As is readily apparent, it is possible, by pushing upward on
lower rolling bearing 50 with a force F, to compress spring 58 and
thereby to displace the two bearings 48, 50, spacing element 52,
and retaining washer 54 upward on shaft 46, so that inner ring 50i
no longer abuts against snap ring 59 but instead ends up at a
distance therefrom. In this case projection 56 of rotor 22 comes
into contact against retaining washer 54 and makes it possible, by
way thereof, to transfer an axial force to retaining washer 54,
outer ring 48e, spacing element 52, and outer ring 50e when rotor
26 is pressed downward with a force K during assembly.
[0057] FIG. 19 shows a "snapshot" during the "mating" operation in
which shaft 46 of rotor 26, with rolling bearings 48, 50 present
thereon, is introduced into internal opening 77 of bearing tube
30.
[0058] In this context, a force K is applied to rotor 26 in the
axial direction; and because outer rings 48e, 50e of rolling
bearings 48, 50 are pressed with a press fit into bearing tube 30,
spring 58 is compressed by force K so that shaft 46 is displaced in
ball bearings 48, 50, and projection 56 acts via retaining washer
54 on outer ring 48e of ball bearing 48 and also via spacing
element 52 on outer ring 50e of ball bearing 50, and thus presses
the two ball bearings 48, 50 into bearing tube 30.
[0059] Pressing-in continues until outer ring 50e of the lower ball
bearing 50 abuts against the upper end of ribs 83 that are provided
in bearing tube 30 at its inner end 60.
[0060] According to FIG. 19, in this context retaining member 54 is
displaced in bearing tube 30 and digs into its plastic material, so
that the entire bearing arrangement latches into bearing tube
30.
[0061] Force K is removed after pressing-in is complete, and what
then results is the situation according to FIG. 1, i.e. spring 58
now once again pushes shaft 46 until snap ring 59 abuts against
inner ring 50i of rolling bearing 50. Spring 58 now clamps the two
inner rings 48i, 50i against one another, which is necessary for
quiet running of motor 20.
[0062] FIGS. 6 to 12 show a first variant for the mounting of
flux-conducting elements 150' on a plastic ring 160. The latter has
a cylindrical opening 162 with which, according to FIGS. 10 and 12,
it is slid onto partitioning tube 82. On its outer side it has
projections 164 in which flux-conducting elements 150' are anchored
in the manner depicted.
[0063] Ring 160 is provided, on its lower side (in FIGS. 6, 7, and
10 to 12), with projections 168 that are approximately
wedge-shaped. The result of impingement with an ultrasonic
transducer in the direction of arrows 170 in FIG. 10 is that these
projections 168 dig into shoulder 84 and become welded to it.
[0064] Partitioning tube 82 can have a thinner wall thickness in
this case.
[0065] FIGS. 13 and 14 show a similar embodiment, except that a
wedge-like edge 174 is provided that extends continuously. The
mounting operation is the same as depicted in FIGS. 10 to 12.
[0066] FIG. 15 shows a section through a ring 160 and through
flux-conducting elements 150'' anchored therein. FIG. 16 shows, in
an enlarged depiction, that flux-conducting elements 150'' in this
variant are thickened in wedge-shaped fashion at the radially inner
end in order to effect secure anchoring. Flux-conducting element
150'' also, according to FIG. 17, has a hook-like enlargement 180
at the radially inner end.
[0067] As is clearly apparent to one skilled in the art from FIG.
1, flux-conducting elements 150 also act as flux concentrators,
since in their radially outer region they have approximately the
same length as magnet 67, whereas in their radially inner region
they have approximately the (shorter) length of magnet 92, so that
the flux of magnet 67 becomes concentrated. This also takes into
account the circumstance that magnets 67 and 92 are of different
lengths, and improves the torque that can be transferred by the
magnetic coupling.
[0068] Numerous variants and modifications are of course possible
within the scope of the present invention.
* * * * *