CA2208482C

CA2208482C - Transverse flux machine

Info

Publication number: CA2208482C
Application number: CA002208482A
Authority: CA
Inventors: Wolfgang Hill
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-21
Filing date: 1995-12-16
Publication date: 2000-04-11
Anticipated expiration: 2015-12-16
Also published as: CN1171174A; CA2208482A1; DE19547159A1; CN1062388C; WO1996019861A1; KR980700720A; JPH10513035A; DE59506252D1; EP0799519B1; EP0799519A1

Abstract

In known transverse flux machines, the losses in the soft magnetic body prevent an increase in efficiency. While the production of the winding is remarkable owing to its simplicity, the production of the laminated iron body conveying the magnetic flux incurs high costs. In addition to the saturation in the iron, the use of air gaps restricts any increase in power density. In accordance with the invention, the two air gaps (21) are arranged radially externally of the winding (15) and the magnetically hard and/or soft magnetic rotor parts (19, 20) which periodically close the magnetic circuit are arranged axially within the ends of the soft magnetic stator body (18). This air gap arrangement gives rise to an air gap surface which is large relative to the external dimensions and the mass of the machine, and also relieves the load on the housing. Owing to the segmentation of this u-shaped stator body, material waste during production is minimized and grain-oriented metal sheets can be used which, owing to their favorable properties, enable the efficiency and power density to be increased. Segments of identical construction can be used in machines having different dimensions and power data. The type of construction according to the invention simultaneously reduces costs, weight, and losses in transverse flux machines.

Description

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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, 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 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.

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 -3a-' CA 02208482 1997-06-20 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 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 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 ' CA 02208482 1997-06-20 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 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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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.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. 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 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.

2. 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.

3. A transverse flux machine as recited in claim 1, wherein the u-shaped soft magnetic body is divided into at least two parts.

4. A transverse flux machine as recited in claim 1, wherein said u-shaped soft magnetic body is divided into 3 segments which conduct the magnetic flux predominantly into one direction and wherein the said segments placed oppositely in said u-shaped soft magnetic body are identical.

5. A transverse flux machine as recited in claim 1, wherein star-shaped flat discs have an outer circumference and conduct the magnetic flux radially toward said outer circumference.

6. A transverse flux machine as recited in claim 1, wherein said hard magnetic parts are ring-shaped and magnetized in opposite directions.

7. A transverse flux machine as recited in claim 1, wherein said ends of said u-shaped soft magnetic bodies have surfaces to said air gap, said surfaces extend simultaneously in axial and radial direction.

8. A transverse flux machine as recited in claim 1 comprising: a rotational axis and constructions, wherein said ends of said u-shaped soft magnetic parts are beveled and said hard magnetic parts in said constructions of soft and hard magnetic parts that close said magnetic circuit are arranged opposite the beveled ends of said soft magnetic parts and wherein said beveled ends of said soft magnetic parts have a beveling angle with reference to the rotational axis of between 45 and 70.

9. A transverse flux machine as recited in claim 1, wherein said conductor ring consists of wound rectangular profile conductors or of hard anodized aluminum strip.