Note: Descriptions are shown in the official language in which they were submitted.
' CA 02208482 1997-06-20
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Wolfgang Hill PCT/DE95/01807
TRANSVERSE FLUX MACHINE
The invention concerns a transverse flux machine with
conductor rings and u-shaped soft magnetic bodies.
A transverse flux machine is impressive because of the
simplicity of its winding. On the other hand, the production of
the soft magnetic body incurs considerably higher costs.
Material costs are increased by the waste incurred in
punching the electric sheets, tool costs are increased by large
and complicated dies, and assembly costs are increased by the
handling of heavy component parts. The attainable efficiency
and/or the power density of the machine are limited due to the
saturation flux density of the soft magnetic material and the
utilization factor of the air gap surfaces.
In DE 42 23 831 A1, a transverse flux machine is
described which shows four winding rings of which two each have
different diameters. The rotor elements are inserted axially
into the four ring grooves of the stator resulting in a machine
with eight air gaps in which the magnetic flux flows in radial
direction.
From GB-PS 1 363 979, a transverse flux machine is
known in which the rotors are arranged axially between the
stators. The stators contain the conductor rings and in each
magnetic circuit exist two air gaps with different radii.
From DE-PS 597 597, a single-phase transverse flux
machine is known whose u-shaped soft magnetic cores are composed
of two parts which are arranged around the conductor ring. The
air gaps are located radially within the conductor ring and the
dynamic effect of the magnetic field shows the same radial
direction in all air gaps. The pulsating radial air gap forces
act on the annular rotor housing and generate vibrations, noise,
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and losses. Therefore, the housing must be of solid and heavy construction.
Also, in the external rotor design known from DE 43 14 513 A1, the
magnetic forces of the two air gaps of a magnetic circuit acting vertically
with
regard to the direction of movement are additive, thereby failing to achieve
the
objective of maximum power density.
GB 2 161 992 A describes a motor which provides rotary actuation in
one direction only and which has u-shaped stator cores consisting of three
parts.
The piece parts which conduct the magnetic flux of the two phases are
separated
by a spacer. The magnetic forces acting radially in the air gap are additive.
From DE 43 14 513 A1, external rotor designs of transverse flux
machines are known in which the magnetic flux radially within the magnetically
active rotor elements flows through the air gap in radial direction. Power
density
is to be increased by more than 2 air gaps on both sides of the winding
arrangement. This air gap arrangement permits the axial sliding into each
other of
rotor and stator at any time.
Numerous other designs of transverse flux machines are known
which, however, utilize the soft magnetic material used only insufficiently
and, in
terms of production engineering, require costly sheet steel stamping.
The present invention provides a transverse flux machine comprising:
at least one rotor and one stator, conductor rings and u-shaped soft magnetic
bodies, said u-shaped soft magnetic bodies having ends, said conductor rings
being enclosed on three sides by said u-shaped soft magnetic bodies; said
machine further having magnetic circuits enclosing said conductor rings and
being
concentrated in said u-shaped soft magnetic bodies and in soft magnetic parts
or
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hard magnetic parts or constructions made of soft and hard magnetic parts,
said
soft magnetic parts or hard magnetic parts or constructions made of soft and
hard
magnetic parts being moveable in relation to said conductor rings and being
separated from said u-shaped bodies by air gaps, said magnetic circuit being
closed periodically, wherein said air gaps are arranged radially outside said
conductor rings, wherein said moveable parts of the rotor or the stator are
partially
arranged within said ends of said u-shaped soft magnetic bodies.
The invention also provides a transverse flux machine comprising:
conductor rings and u-shaped soft magnetic bodies, said u-shaped soft magnetic
bodies having ends, said conductor rings being enclosed on three sides by said
u-
shaped soft magnetic bodies; said machine further having magnetic circuits
enclosing said conductor rings and being concentrated in said u-shaped soft
magnetic bodies and in soft magnetic parts or hard magnetic parts or
constructions made of soft and hard magnetic parts, said soft magnetic parts
or
hard magnetic parts or constructions made of soft and hard magnetic parts
being
moveable in relation to said conductor rings and being separated from said u-
shaped bodies by air gaps, said magnetic circuit being closed periodically,
said air
gaps being arranged radially outside said conductor rings, wherein said u-
shaped
soft magnetic bodies contain comb-shaped segments, said comb-shaped
segments consisting of tangentially layered stamped parts and enclosing at
least
two conductor rings on three sides, wherein parts of said comb-shaped segments
arranged between two conductor rings are alternately flown through by the flux
of
different phases and wherein said conductor rings of different phases are
separated by said soft magnetic bodies which said conductor rings jointly
utilize.
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CA 02208482 1999-OS-17
In the assembly, either the stator and rotor rings are placed
alternately into position or the rotor ring consists of several identical
parts, e.g. two
halves. The combination - arrangement of both air gaps of a magnetic circuit
radially outside the conductor ring with maximum distance to the rotational
axis,
and compensation of the air gap forces by the yoke parts which lie within the
ends
of the u-shaped parts - leads to astonishingly high power densities and
efficiencies.
Another basic idea of the invention is the multiple utilization of soft
magnetic piece parts of a magnetic circuit by the magnetic fields of adjacent
conductor rings of different phases. By this, a higher temporal utilization of
the
soft magnetic material is achieved in which the weight ratio of this mass
which is
utilized by the phase-shifted magnetic fields increases with an increasing
number
of phases. Structural components of different phases consist of identical
discs
which are arranged axially in series.
Further, in order to facilitate simple assembly and the use of grain
oriented stampings, the u-shaped stator cores consist advantageously of
several
segments which lead the flux predominantly into one direction. In subdivided
rotor
rings, the stator cores may, however, be prefabricated as single piece, e.g.
as
grain oriented stamped coil cores.
Advantageous embodiments of the invention are displayed
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Wolfgang Hill PCT/DE95/01807
in the drawings.
Fig. 1 shows the assembly of a single-phase structural
component of a 24-pole transverse flux machine in
accordance with the reluctance principle;
Fig.2 shows a cutout from Fig. 1;
Fig.3 shows four cros s sections of different magnetic
circuits with ard magnets;
h
Fig.4 shows the cross section of a three-phase wheel hub
direct drive;
Fig.5 shows the cross section of a five-phase rotary motor;
Fig.6 shows the cross section of a three-phase drive with
doubly utilized center star disks;
Fig.7 shows the flux and current progressions of the machine
in Fig. 6;
Fig. 8 shows an isometric view of the active piece parts from
Fig. 6.
Figure 1 shows the essential design elements of a
modularly designed transverse flux machine during assembly. The
conductor ring 1 consists of a coiled copper or aluminum strip.
Twenty-four evenly spaced soft magnetic bodies are arranged
around the circumference of said conductor ring. Each of these
bodies which bundle the electrically generated magnetic field
consist in turn of four laminated segments 2, 3, 4 and 5 of which
the two oppositely situated segments 2 and 3 or 4 and 5
respectively are identical. The two segments 2, 3 which conduct
the magnetic flux radially are glued onto carrier discs 6, 7
which consist of magnetically and electrically nonconducting
material and wherein the segments 3 are shown axially in front of
the carrier disc 7 in order to clarify their design and
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Wolfgang Hill PCT/DE95/01807
arrangement. The segments 4, 5 which conduct the magnetic flux
axially are glued to carrier rings 8, 9. Besides the conductor
ring 1 and the two soft magnetic segments 2, 3 or 4, 5
respectively, the single-phase structural component consists
therefore of two identical carrier discs 6, 7 as well as two
different carrier rings 8, 9.
Figure 2 shows a cutout from Fig. 1, enlarged. It can
be seen how four segments 2, 4, 3, 5 each form a circuit which
amplifies the magnetic field around the conductor ring 1. Here,
the segments 2, 3, and 4 are abutting and are fixed in their
location, while the radially outer segments 5 together with the
outer carrier ring 9 rotate around this arrangement during which
the resistance of the magnetic circuit varies periodically.
Figure 3 shows four advantageous structural designs 11
to 14 as cross sections in which the view is limited to the
conductor ring 15a-d and the magnetic body surrounding it.
The conductor rings 15a-d are enclosed on three sides by the u-
shaped soft magnetic bodies 16a-d. These consist of two or three
abutting segments 17a-18d' which conduct the flux predominantly
into one direction and wherein the two segments 18a-d or 18a'-d'
respectively which conduct the flux radially are identical. The
hard and/or soft magnetic segments 19a, b, d or 20a-c
respectively which are arranged outside the conductor ring 15a-d
are different from each other.
In design 11, the permanent magnets 20a, 20a' arranged
at the beveled air gap 21a decrease the pulsation losses. Thanks
to the beveling, a high flux density in the segments 18a, 17a,
18a', 19a can be achieved with low flux densities in the magnets.
The hard magnetic as well as the soft magnetic material is
CA 02208482 1997-06-20
Wolfgang Hill PCT/DE95/01807
optimally utilized.
In less costly and easier to handle permanent magnets
20b, the outer segment in design 12 consists of two identical
halves 19b~ 19b'. The soft magnetic body 16b which encloses the
conductor ring 15b in a u-shape is identical to the one in Fig.
3a.
In axially very narrow designs 13, the outer soft
magnetic segments may be deleted. Only an annular permanent
magnet 20c which is magnetized by sectors in axially opposite
direction is placed between the ends of the two radial segments
18c,, 18c' .
With fewer parts, yet with utilization of grain
oriented material, design 14 can be achieved. It consists of
three parts 18d~ 18d', 19d of a rectangular wound stamped coil
core 16d. In order to compensate the more strongly pulsating
magnetic normal force in the reluctance machine, the narrow air
gaps 21d are arranged radially.
Further, differently prefabricated conductor rings 15a-
d are shown in Fig. 3. The two-layer conductor ring 15a can be
advantageously manufactured with two ends lying radially on the
outside by appropriately shaping the middle section of a profile
wire and winding the two identically long ends in opposite
directions. With a multi-layer conductor ring 15b of profile
wire, a high space factor can be achieved, axially narrow
machines permit single-layer conductor rings 15c, and at a high
number of turns and a groove cross section that deviates from the
rectangular shape, condensed conductor rings 15d of round wire
can be used.
In Fig. 4, the cross section of a complete three-phase
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Wolfgang Hill PCT/DE95/01807
transverse flux machine 22 is shown as wheel hub direct drive
with permanent excitation. The design of the magnetically active
part corresponds to Fig. 3d. The magnetic rings 23 consist of
plastic bonded rare earths magnets, the single-layer conductor
rings 24 of thin conductor coil strip, and the u-shaped soft
magnetic bodies 25 of grain oriented electric sheets which have
been packeted with baking enamel.
All three single-phase structural components are
identical and are held in place, offset in relation to each other
by 120°~1, by five retaining elements 26a-c. By utilization of
mirror symmetries, only three different retaining element designs
are required which are prefabricated as cast parts. The hub 26
with is formed by the retaining elements, as well as the five-
part rotor 27a-c are held together by screws 28, 29 which are
inserted alternately from different sides. Forces transmitted
from the wheel spokes 30 are transferred via the ball bearings 31
to the hub 26. The drive electronics are housed in a hollow
space 32 within the hub.
Fig. 5 shows the cross section of a five-phase
transverse flux machine 33 which is executed as a reluctance
machine. The identical structural elements 34a-a are arranged
within the stationary part in a tangentially offset manner in
relation to each other which causes the cross sections of the u-
shaped soft magnetic bodies 35 to be visible at various degrees
of completeness. While only two different stationary retaining
elements 36, 37 are required, the rotating machine housing, due
to the beveled air gaps 38, is composed of five outer retaining
rings 39 with soft magnetic segments 40, as well as four spacer
rings 41 and the two motor shields 42 which are supported via
bearings 43 on the shaft 44. Executed as a rotary motor, the
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Wolfgang Hill PCT/DE95/01807
rotor is covered by a rubberized casing 45.
Alternatively, the housing can be executed as
stationary and the then rotating conductor rings 46 can be
triggered by brushes or co-rotating exciting machines.
Additional embodiments, e.g. with a barrel-shaped rotor, can also
be realized in accordance with the modular design principle of
the present invention.
Fig. 6 represents a three-phase drive 47 in which the
three conductor rings 48 are wrapped directly into the comb-
shaped soft magnetic bodies 50 which are already positioned on
the hub 49. The rotor consists of two halves 52 which contain
soft magnetic block segments 51. After radial joining of the
halves, a barrel-shaped body 53 is slipped over it axially. The
comb-shaped segments consist of tangentially layered stamped
parts with radial grain orientation. The common bark 5d ;
executed broader than the four teeth 55a-d wherein the middle
teeth 55b, c are sequentially flown through by the magnetic flux
of the two conductor rings separated by said teeth.
In Fig. 7, the temporal sequence of the magnetic
induction is shown in the two upper line diagrams for the second
and third tooth 55b, c. The magnetic circuit of the middle
conductor ring together with the two magnetic circuits of the
adjacent phases utilizes the middle teeth 55b, c, wherein the
flow through is staggered and the utilization time is doubled.
This multiple utilization results in an increase of the power
density. In the three-phase reluctance machine, the currents
commutate either - as shown in line diagram 58 - in 120°gl
blocks, so that a constant motor current is flowing, or they
overlap in blocks > 120°~1 in such a manner that the moment
ripple is decreased.
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.. .: _~ ~. .,. CA 02208482 1997-06-20 _-. ~. .: :.:.. , ~.:. .. .-,;
Wolfgang Hill PCT/DE95/01807
In Fig. 8, the magnetically and electrically active
design elements of a three-phase drive are shown. The soft
magnetic body 59 of the 36-pole stator consists herein of four
identical star discs 60a-d and three identical ring cores 61.
These prefabricated piece parts and the three identical conductor
rings 62a-c are assembled alternately in axial direction. The
current supply of the middle conductor ring 62b occurs preferably
at the bottom of the groove by adjacent phases or through holes
and/or slits in the ring core. The soft magnetic block segments
63 of the different phases which are offset by 1/3 pole pitch in
relation to each other are advantageously initially cast into
identical rings which are axially toothed to that the offset is
ensured during assembly. In high-pole annular drives, the star
discs 60a-d may also be manufactured from grain oriented electric
sheets wherein the stamped parts comprise only few pole pitches.
For drives of highest power density, an additional
increase of the number of phases is advantageous wherein the
portion of the multiply utilized mass as well as the width of the
current blocks may be increased to, e.g. 2/5 or 3/7 of the
period.
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