DE19832390A1 - Transverse flux electrical machine e.g. for vehicle generator and wind generator - Google Patents

Abstract

Has stator lamination packet made of strips stepped in width folded to profile with U-shaped section and then bent into ring. An electrical machine with transverse flux guidance through an armature ring of U-cross-section and rotor discs with claw poles has a stator lamination packet made of strips stepped in the width which are folded in the packet to a profile with a U-shaped section and are then bent to a ring. The strips are preferably stamped as strips with a grain-oriented cross-section. For large series, slit strips with a width corresponding to the strip length are used and the stepped strip width is created with a single stamping tool by a corresponding lamination advance at the stamping press. The pole teeth and tooth spaces are at the same time designed symmetrically.

Description

The invention relates to an electrical machine preferably suitable for the Use as an alternator in motor vehicles and as a generator in small ones Wind turbines with a power of some 100 W.

Alternators are usually designed as separately excited three-phase machines and to maintain a cost-effective size with a quick translation Gear driven.

Occasionally, multi-pole machines with three-phase windings are also used and radial or axial flow guidance in different designs.

The use of transverse flow guidance promises a significant increase in specific performance and particular suitability for a gearless drive with low speed.

The high operating frequency and the simple winding shape allow in principle good material utilization with low power loss.

However, transversal flux machines with corresponding performance that have been implemented so far have a complex structure from a large number of individual parts and are therefore uneconomical compared to proven concepts. Only with generators low power (bicycle dynamo) is the principle in very affordable solutions been implemented.

The aim of the invention is the principle of transverse flow guidance for the area small and medium power in an inexpensive electrical machine with simple Implement the structure.

For this purpose, a "stator core package" ( 12 ) made of sheet metal strips with pole teeth ( 23 ) punched out on both sides and layered in width is layered. In the package, the pole teeth are folded to a U-shaped cross-section and the straight U-profile is then bent round. This creates two narrow cylindrical pole faces.

Before deforming, especially round bending or edging into one The sheet metal strips are expediently polygonal by gluing, spot welding or Fix punches against each other.

Small diameters can be made from one-piece sheet metal strips, larger diameters are composed of several sections. A multi-part design is also advantageous for inserting form coils ( 13 ).

The finished stand plate is stabilized by a cylindrical housing ( 11 ).

The similar flow direction enables the use of low-loss grain-oriented transformer sheets.

The rotor ( 3 ) is formed from groups of pole disks ( 6 , 7 ) arranged axially one behind the other, each consisting of layered dynamo plates, in which pole teeth ( 22 , 23 ) are punched out on the circumference and engage in a claw-like manner. The pole disks are separated from each other by an excitation device. There are several simple options for executing the excitation: For electrical excitation, an iron core ( 15 ) with excitation winding ( 17 ) is arranged between two pole disks. For excitation with permanent magnets, either axially magnetized permanent magnet disks ( 18 ) (preferably inexpensive ferrites) are arranged between the magnetically insulated pole disks, or the pole disks are connected to a common cylindrical iron core via radially magnetized cylindrical permanent magnets. Only one (preferably neodymium) magnet is required per phase.

Finally, electrical and magnetic excitation can be combined ( Fig. 1) by alternately using a coil ( 17 ) and a magnet ( 18 ). The excitation coil is then activated in a bipolar manner to regulate the excitation. This enables low-loss control of the machine with a slightly more complex controller. A medium excitation is set by the permanent magnet, which is amplified or weakened by the coil as required.

The energy for electrical excitation is usually transmitted electrically through sliding contacts that are subject to wear due to abrasion. Magnetic transmission through air gaps, on the other hand, is wear-free, but requires a larger magnetizing current. With combined excitation, the electrical losses can be coped with and the advantage of wear-free transmission can be used. A favorable arrangement is the transmission of the coil induction through cylindrical air gaps ( 10 ) in the pole disks ( 7 , 8 ) and the transmission of the magnetic induction via a large axial air gap between the magnetic disk ( 18 ) and the pole disk ( 5 ).

Fig. 1 and 2 show a structure corresponding to the example of an alternator. The stand ( 2 ) with its housing ( 11 ) is mounted directly on the internal combustion engine ( 1 ). The rotor is attached to a bearing journal ( 3 ) on the crankshaft. A separate storage of the alternator is not necessary. The excitation apparatus is pressed and centered in the sheet metal housing. The electrical excitation takes place via a coil ( 17 ) which is arranged between two laminated disks ( 16 ) and over a cylinder laminated lengthways with strips ( 15 ). For magnetic excitation, a magnetic ring ( 18 ) is glued to a disk ( 16 ), in front of which the rotor disk ( 5 ) moves. The rotor disk ( 5 ) is used for fastening to the shaft journal ( 3 ) and it transmits the torque to the rotor disks ( 6 ) and ( 7 ), with which it is connected by rivets ( 8 ) and spacer sleeves ( 9 ).

The rotor disks differ in their tooth pitch and the cranking of the teeth. The outer discs ( 5 ) and ( 7 ) have z. B. 24 pole teeth, the inner disc ( 6 ) has twice the number of teeth that are alternately cranked between the pole teeth of the outer discs, the disc ( 7 ) also has a center offset to create enough space for the excitation winding . The disc ( 5 ) can be designed without cranking.

Fig. 2 shows the assignment of the pole teeth. A view is shown at the top, a section through the excitation coil at the right. On the left a section through the magnetic disk.

Fig. 3 shows the individual sheet cuts.

The proposed solution offers the following advantages:
Simple and reliable construction, belt transmission, storage and sliding contacts are no longer necessary.

Simple manufacturing with proven manufacturing processes.

Low material costs due to short iron paths and little waste. Copper savings through simple coil shape.

Inexpensive magnet material and only one magnet with simple geometry. Good efficiency through the use of grain-oriented sheets in the anchor, a good one Utilization of the armature winding and low-loss excitation.

The moment of inertia of the rotor mounted directly on the crankshaft replaces one Part of the flywheel mass, this results in a weight saving of the system.

Due to the single-phase design, a greater effort for smoothing the Current required after rectification, the required capacity of one Smoothing capacitor is low due to the relatively high frequency.  

Fig. 4 shows schematic diagrams of a 1- or 2-phase machine, the assembly of radially magnetized magnet rings and the arrangement of the outer and middle rotor disks.

Fig. 5 shows an embodiment for a 1-phase machine with storage, as it can be used for wind generators. Fig. 6 shows the possibility of producing multi-phase machines by the axial juxtaposition of identical stator and rotor units using the example of a 3-phase machine.

Fig. 7 shows a 2-phase arrangement with stationary electrical excitation, the z. B. could be used for a combination of starter and alternator of an internal combustion engine.

Fig. 8 shows a 1-phase version with a permanently magnetically excited external rotor, which can be used as a wheel hub motor or generator.

Claims (4)

1. Electrical machine, with transverse flow guidance characterized by an anchor ring with a U-shaped cross section and rotor disks with claw poles, a stator laminated core made of sheet metal strips ( 12 ) stepped in width with pole teeth ( 23 ) punched out on both sides, which in the package form a profile with a U -shaped cross section ( 12 ) and then bent into a ring ( 12 ).
The metal strips are preferably punched as cross sections of grain-oriented metal sheets. For large series, slit strips with a width corresponding to the strip length are used and the stepped strip width is generated by a corresponding sheet feed on the stamping press with a single stamping tool, the pole teeth and tooth gaps are designed symmetrically. 2. Two outer rotor disks and one middle rotor disk for each phase. Each rotor disk ( 5-7 ) consists of layered packages of stamped and glued sheets, the pole teeth (sheet by sheet individually) are offset against each other, the outer rotor disks having teeth corresponding to the pole pitch, which are cranked inwards, and the middle ones Rotor disks ( 6 ) have twice the number of teeth, which are alternately cranked on both sides.
The offset corresponds to the width of the stator core, so that the stator poles and rotor poles with alternating magnetic polarity on cylindrical air gaps are opposite each other. The length of all pole faces of a cross section is approximately one third of the circumference.
One or both outer rotor disks ( 6 ) are designed without an offset, especially in connection with permanent magnetic excitation.
In the case of external runners and internal runners with a large diameter, the rotor plates are punched as strips with notches ( 25 , 26 ) on both sides and folded into rings in the plane of the plate.
Depending on the application, the strips for these rotor laminated cores are preferably made as cross sections from grain-oriented laminations or, in the case of large series, are continuously punched out of split strips and wrapped around the vertical axis to form packages. 3. The combined electrical and permanent magnetic excitation of the rotor by alternating between the rotor disks mounted excitation coil ( 17 ) or permanent magnetic disc ( 18 ), which is arranged between two magnetically insulated rotor disks, or a permanent magnetic ring, each under the (middle ) Rotor disc and on an iron anchor ( 15 ) is arranged ( Fig. 4). The transmission of excitation energy from a stationary excitation apparatus through coaxial radial ( 10 ) and / or axial air gaps. 4. The formation of multi-pole machines through the axial alignment of identical construction Stand / runner units.