EP0506660A1

EP0506660A1 - Permanent-magnet-excited electric machine, especially one with a high rotation speed

Info

Publication number: EP0506660A1
Application number: EP90913400A
Authority: EP
Inventors: Horst KÜMMLEE
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1989-12-22
Filing date: 1990-09-13
Publication date: 1992-10-07
Also published as: DE3943237A1; WO1991010277A1

Abstract

Dans le cas de machines à excitation par aimants permanents, les aimants permanents (5) et pièces intercalaires (6) en métal amagnétique disposés sur le corps (3) du rotor sont retenus par une frette (7) située dans l'entrefer (9), laquelle est en matière plastique renforcée par fibres de résistance élevée. Lorsque la machine tourne, cette frette (7) s'élargit plus fortement que le corps (3) du rotor (1), même si elle est précontrainte, de telle façon qu'il peut y avoir des défauts d'équilibre. Pour maintenir le centrage, la surface externe (4) du corps de rotor (3) est subdivisée, selon l'invention, sur toute la longueur axiale par des évidements (11) et la rigidité d'extension du corps de rotor (3) en sens radial est adaptée, par des mesures de construction particulières, de manière approximative à la rigidité de la frette (7) avec les aimants permanents (5). Les évidements (11) forment des fentes (12) radialement extérieures et ont radialement à l'intérieur des extensions (14, 15) arrondies pour éviter l'effet d'entaille. Sur un rayon plus petit, on peut encore prévoir des évidements arrondis (16) supplémentaires. Un tel rotor d'une machine électrique à aimants permanents convient en particulier à des machines à grande vitesse de rotation.In the case of machines with permanent magnet excitation, the permanent magnets (5) and spacers (6) made of non-magnetic metal arranged on the body (3) of the rotor are retained by a hoop (7) located in the air gap (9 ), which is made of high strength fiber reinforced plastic. When the machine rotates, this hoop (7) widens more strongly than the body (3) of the rotor (1), even if it is pre-stressed, in such a way that there may be faults in balance. To maintain the centering, the outer surface (4) of the rotor body (3) is subdivided, according to the invention, over the entire axial length by recesses (11) and the tensile stiffness of the rotor body (3) in radial direction is adapted, by special construction measures, approximately to the rigidity of the hoop (7) with the permanent magnets (5). The recesses (11) form radially outer slots (12) and have radially inside extensions (14, 15) rounded to avoid the notch effect. On a smaller radius, it is still possible to provide additional rounded recesses (16). Such a rotor of an electric machine with permanent magnets is particularly suitable for machines with a high rotational speed.

Description

(51) International Patent Classification ⁵ (11) International Publication Number: WO 91/10 H02K 1/27 AI (43) Internationales

RELEASE DATE: July 11, 1991 (Jul 11

(21) International file number: PCT / DE90 / 00710 (81) States of destination: AT (European patent), BE (European patent), CH (European patent), DE (e

(22) International filing date of the European patent) *, DK (European patent), ES (e 13 September 1990 (13.09.90) European patent), FR (European patent), GB (European patent), IT (European patent) , JP, LU (European patent), NL (European patent), SE (euro

(30) Priority data: United States patent.

P 3943 237.8 December 22, 1989 (December 22, 1989) DE

Released

(71) Applicant (for all destination countries except US): SIE¬ With international search report.

MENS AKTIENGESELLSCHAFT [DE / DE]; Wittelsbachplatz 2, D-8000 Munich 2 (DE).

(72) inventor; and

(75) Inventor / applicant (only for US): KÜMMLEE, Horst [DE / DE]; Am Krähenberg 16, D-1000 Berlin 27 (DE).

(74) Common representative: SIEMENS AKTIENGESELL¬ SCHAFT; Postfach 22 16 34, D-8000 München 22 (DE).

(54) Title: PERMANENT-MAGNET-EXCITED ELECTRIC MACHINE, ESPECIALLY ONE WITH A HIGH ROTATIO SPEED

(54) Designation: PERMANENTLY MAGNETIC ELECTRIC MACHINE, ESPECIALLY HIGH SPEED

(57) Abstract

In permanent-magnet-excited electric machines, the permanent magnets (5) arranged on the Stator body (3) of the rot and spacers (6) of non-magnetic material are held by a facing (7) of sturdy, fiber-reinforced plastic in the air gap (9). When t machine is running, this facing (7) expands to a greater extent than the Stator body (3) of the rotor (1), even if it is prestresse and hence imbalances may arise. According to the invention, in order to keep the arrangement centered, the outer surface (4) of t Stator body (3) is divided up over its entire axial length by recesses (11) and the radial elasticity of the stator body (3) is approx mately matched to that of the facing (7) with the permanent magnets (5) by Special structural measures. The recesses (11) for slots (12) lying radially on the outside and have radially inwardly rounded enlarged sections (14, 15) to prevent stresses. F smaller radii further rounded recesses (16) may also be provided. Such a rotor of a permanent-magnet-excited electric machine especially suitable for high rotation speeds. (57) Summary In permanent magnet excited electrical machines, the permanent magnets (5) and filler pieces (6) made of non-magnetic material, which are arranged on the rotor bale (3) of the Roto, are held by a banda (7) made of high-strength, fiber-reinforced plastic in the air gap (9). When the machine is operating, this bandage (7) widens more than the rotor bale (3) of the rotor (1), even if s is under tension, so that imbalances can occur. To retain the centering according to the invention, the outer surface (4) of the rotor bale (3) is divided over the entire axial length by recesses (11) and the tensile stiffness of the rotor bale (3) in the radial direction is approximated by special structural measures Rigidity of the bandage (7) adjusted with the permanent magnets (5). The recess (11) form radially outer slots (12) and have rounded extensions (14, 1) on the radially inner side for the purpose of notch-freeness. Additional rounded recesses (16) can also be provided on a smaller radius. Such a gate of a permanent magnet excited electrical machine is especially suitable for high-speed machines.

TERMS OF "DE"

For the time being, any designation of "DE" in an international application whose international filing date is before October 3, 1990 has effect in the territory of the Federal Republic of Germany with the exception of the territory of the former GDR.

LEDIGUCH FOR INFORMATION

Code used to identify PCT contracting states on the headings of the publications that publish international applications in accordance with the PCT.

1 Permanent magnet excited electrical machine, especially high speed

The invention relates to a permanent magnet-excited electrical machine, in particular high speed, in which the permanent magnets and filler pieces made of non-magnetic material arranged on the rotor bale of the rotor are held by a bandage made of high-strength, fiber-reinforced, in particular carbon-reinforced, plastic located in the air gap.

Such a permanent magnet-excited electrical machine is known from DE-OS-32 24 904. Since highly permanent permanent magnets cannot be used as load-bearing material due to their internal structure, but are sensitive to shock loads and tensile stresses, the permanent magnets used to excite the known electrical machine and the filler pieces made of non-magnetic material for the pole gaps on the rotor bale of the rotor are either included a jacket made of high-strength, non-magnetic metals or held together by a bandage made of fiber-reinforced, in particular carbon-reinforced plastic (CFRP) under tension. In the known machine, the pretensioning of the jacket or the bandage is produced either by wedging or by the thread pull during the winding of the bandage. Wedging is complex and an increase in the bandage thickness is limited by the electrically prescribed maximum dimensions of the air gap between the stator and the rotor of the electrical machine in which the bandage is located.

For this reason, especially in the case of high-speed, permanent magnet-excited electrical machines, the permanent magnets of which are held on the rotor bale by a plastic bandage, unbalance due to asymmetrical radial displacements of the permanent magnets at higher circumferential speeds cannot be avoided with certainty because the bandage of plastic bandages The permanent magnet stretches more at centrifugal force than the bale. This creates a gap between the permanent magnet and the rotor bale, which can lead to variable imbalances. The object of the invention is to avoid such imbalances.

To achieve this object, in a permanent magnet-excited electrical machine of the type described at the outset according to the invention, the outer surface of the rotor bale facing the bandage is divided in the circumferential direction by a plurality of cutouts which extend over the entire axial length, and the expansion stiffness is achieved by special design measures speed of the sub-areas of the runner bale in the radial direction is approximately adapted to the elastic stiffness of the bandage with the permanent magnets. It is not, as was previously the case, that the pre-tension of the jacket holding the permanent magnets or the bandage is increased, but the rotor bale is divided on the outer surface by cutouts into several successive partial areas in the circumferential direction, so that there is expansion due to centrifugal stresses there no tangential tensions can occur. The partial areas are each enabled by structural measures to follow the expansion of the plastic bandage and the permanent magnets without play, so that the centering of the permanent magnets is maintained even at high peripheral speeds. A machine designed in this way can therefore advantageously be used for the gearless drive of high-speed work machines.

In a further development of the invention, the adjustment of the radial stiffness of the partial areas of the runner bale can be achieved in that the radially outer part of the recesses each form a slot which opens onto the surface of the runner bale facing the bandage, while the radially inner part of the The recess is widened and has a rounded contour with a sufficiently large notch radius. The outer surface 3 of the runner bale is thus interrupted by the slots and the remaining webs between the recesses can yield to the stresses caused by the centrifugal force by bending and thus follow the deformation path of the bandage with the permanent magnets without play, without causing excessive stresses in the runner bale. The rounded contour of the radially inner extensions of the cutouts also results in a low notch stress transition from the interrupted area to the undivided area of the bale.

The number and shape of the cutouts and in particular the length and shape of the slots are selected such that the partial areas of the rotor bale are slightly softer than the bandage, so that there is always a residual contact pressure of the permanent magnets on the rotor bale at all operating speeds or circumferential speeds is guaranteed. It is recommended that the slots open into the area of the pole gap.

The slots in the radial plane can advantageously have a curved curve shape which is approximately tangentially directed at the junction with the surface of the rotor bale. The partial areas of the runner bale lying between the slots can then, like a spoke, cause the outer diameter of the runner bale to expand when the centrifugal force is slightly turned relative to the inside diameter, without excessive tangential stresses occurring in the process.

It is expedient to design the runner bale in the case of slits shaped in this way as a laminated body, which is therefore composed of dynamo sheets which can be punched and / or cut. This not only simplifies the production of the recesses with the complicated shapes of the enlargement and the slots (e.g. by erosion), but also enables the deformation energy in the centrifugal force to be absorbed simply by bending over the high one Edge of the sheet metal web between the slots. The radially inner part of the sheet of the bale is therefore not as highly stressed as that of a closed disc.

It is also advisable, especially for slots that open radially into the outer surface of the runner bale, to provide, in addition to the rounded extensions of the cutouts in the runner bale, further rounded cutouts, each of which is on a smaller radius than the extensions of the first cutouts and to these in Are arranged offset staggered. These additional rounded recesses are also effective as relief openings for reducing the notch and reducing the stiffness of the bale. If these additional cutouts have an elongated extension in the circumferential direction, then spring beams which are similar to bending beams and which are particularly soft in the radial direction are produced in the circumferential direction.

The number of recesses and their curve shape will be selected so that the rotor bale is subjected to the same stress in all cross-sections and that the guidance of the magnetic excitation field is not impaired. Ideally, the sheets of the runner bale should open just as much under the centrifugal force as the bandage with the permanent magnets. The slot widths over the radius can also be selected in connection with the pretensioning of the bandage so that when the bandage is at a standstill, the slits are compressed by the pretensioning of the bandage, so that the stress on the nominal speed is reduced.

For guiding the permanent magnets and filler pieces on the rotor bale without play, as a further alternative embodiment of the invention, radially acting spring elements, which are located between the rotor bale and the permanent magnets, can also be arranged in the recesses open to the outer surface, which form the partial regions of the rotor bale or filling Support 5 pieces. The occurrence of imbalances is then avoided by the spring force.

The invention is explained in more detail below with reference to the exemplary embodiments schematically shown in FIGS. 1 to 4 of the drawing, to which the invention is not limited, however. The figures each show a part of a radial section through the rotor, designed according to the invention, of a high-speed permanent magnet-excited electrical machine. The same reference numerals are used for the same parts.

The rotor 1 of a permanent-magnet high-speed electrical machine consists of a rotor bale 3 arranged on the shaft 2 and made of magnetic material, which is used to conduct the magnetic flux. The rotor bale 3 can be of solid construction, made of steel or composed of dynamo sheets.

To generate the magnetic flux 3 ring sector-shaped permanent magnets 5 are arranged on the outer surface 4 of the rotor bale 3, between which also ring sector-shaped filler pieces 6 made of non-magnetic material, such as. As aluminum, are arranged, which form the pole gaps. These permanent magnets 5 and filler pieces 6 are held on the surface 4 of the runner bale 3 by a bandage 7 which consists of plastic which is reinforced with carbon fibers (CFRP) and, in the hardened state, a high-strength bandage which is under tension 7 forms, which presses the permanent magnets 5 and filler 6 firmly against the surface 4 of the bale 3.

In Figure 1, the bore diameter 8 of the stator of the machine, not shown, is indicated by an arc. The bandage 7 lies within the electrical air gap 9 of the machine, indicated by arrows, so that as a result of the required strength and prestress

Claims

1. Permanent magnet-excited electrical machine, in particular high speed, in which the permanent magnets (5) and filler pieces (6) arranged on the rotor bale (3) of the rotor (1) are made of non-magnetic material through a bandage (7) lying in the air gap (9) high-strength, fiber-reinforced, in particular carbon-reinforced, plastic, characterized in that the outer surface (4) of the bale (3) facing the bandage (7) through a plurality of recesses (11) which extend over the entire axial length, in The circumferential direction is divided into sub-areas (13) and that the expansion stiffness of the sub-areas (13) of the bale (3) in the radial direction is approximately adapted to the expansion stiffness of the bandage (7) with the permanent magnets (5) by means of special constructive measures.

2. Permanent magnet excited electrical machine according to claim 1, characterized in that the radially outer part of the recesses (11) of the rotor barrel (3) each form a slot (12, 18) on the surface of the bandage (7) facing (4th ) of the runner bale (3) opens out, while the radially inner part of the recess (11) is expanded and has a rounded contour with a sufficiently large notch radius.

3. Permanent magnet excited electrical machine according to claim 2, d a d u r c h g e k e n n z e i c h n e t that the radially inner extension (14) of the recess (11) is designed as a bore (15).

4. Permanent magnet excited electrical machine according to claim 2 or 3, characterized in that the slots (12, 18) open into the area of the pole gap (19).

5. Permanent magnet excited electrical machine according to one or more of claims 2 to 4, characterized in that in addition to the in the surface (4) of the runner bale (3) opening recesses (11) in the runner bale (3) further rounded recesses (16, 23) are provided, each of which lies on a smaller radius than the extensions (14) of the first recesses (11) and is arranged offset to these in the circumferential direction.

6. Permanently excited electrical machine according to claim 2 or 3 or 4, characterized in that the slots (18) in the radial plane have a curved curve shape, which is approximately tangentially directed at the junction in the surface (4) of the rotor bale (3) is.

7. Permanent magnet-excited electrical machine according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the recesses (11) contain radially acting spring elements (25) which are supported on the permanent magnet (5) or filler pieces (6) and the rotor ball (3).

8. Permanent magnet excited electrical machine according to one or more of claims 2 to 7, d a d u r c h g e k e n n z e i c h n e t that the

Runner bale (3) composed of dynamo sheets (17).