EP2826129A2

EP2826129A2 - Efficient electric machine

Info

Publication number: EP2826129A2
Application number: EP13714845.8A
Authority: EP
Inventors: Sunny Zhang; Daniel FIEDERLING; Joachim Baumgartner; Jin Xu
Original assignee: Brose Fahrzeugteile SE and Co KG
Current assignee: Brose Fahrzeugteile SE and Co KG
Priority date: 2012-03-13
Filing date: 2013-03-13
Publication date: 2015-01-21

Abstract

The invention relates to an electric machine, in particular an electric motor having a stator (2) and a rotor (1, 1') which is mounted so as to be rotatable about a rotor axis (3) and has a rotor body (4), in which at least two permanent magnets in the form of component magnets (17, 17', 18, 18', 18", 24, 24', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49, 57) are arranged in receptacles (5a, 6a), a first of which component magnets is associated with a first set of permanent magnets, and a second of which component magnets is associated with a second set of permanent magnets, and wherein the permanent magnets of the first set differ from the permanent magnets of the second set with respect to the material composition, in particular with respect to the magnetic properties, and wherein at least one permanent magnet of the first or second set or at least one composite body (47) has a contour, the cross-sectional face of which, being located perpendicularly with respect to the longitudinal axis (7), decreases within the respective receptacle (5a, 6a, 35a, 47a, 55a, 55'a) towards that end (5b, 6b) thereof which is radially further to the outside.

Description

description

Efficient electric machine

The invention is in the field of electrical engineering and deals in particular with rotating electrical machines, for example electric motors or generators.

In particular in automotive engineering, d. H. In motor vehicles, more and more electric motors are used in the form of control elements for the assistance of drivers or passengers (windows, sunroof drive, seat adjustment). In addition, electric motors are also in the support systems for the drive, for example, as an actuator for the transmission and as a fan motors and even the actual vehicle drive itself application. The electric motors used there must meet increased requirements by being light to reduce vehicle weight and yet have a high power density. In addition, a long service life and high reliability is required. Ultimately, especially at the engines that are used in the vicinity of an internal combustion engine, a corresponding operational safety is required even at temperatures of at least 120 ° C or up to 180 ° C.

In principle, brushed electric motors (commutator motors) or brushless electric motors can be used whose motor is driven in a rotating field of a stator, wherein usually the stator is equipped with the correspondingly driven windings and the rotor with permanent magnets. Both the rotor and the stator are usually constructed using laminated cores, wherein the individual sheets are insulated from each other to reduce parasitic eddy currents, for example by paint layers. Within the laminated cores so-called stator teeth are provided in the stator with stator slots therebetween, wherein the stator teeth carry a field winding, which is arranged within the stator slots. The field winding is often controlled by means of an electronic circuit which, according to a nem time winding individual winding parts energized and thus generates a rotating field, often a pulse width modulation technique is used to control.

If high demands are placed on the efficiency and power density of such motors, the requirement arises that the rotor gap, i. the gap between the rotor and the stator which also determines the distance between the permanent magnets of one side and the magnetic poles of the other side is designed to be as small as possible. It can unwanted magnetic fields, for example, by self-induction of the field winding arise, which can lead to demagnetization of the permanent magnets, especially at higher operating temperatures. As a result, this leads to a reduction in the power and the power density of the machine. Magnetic materials or alloys with the highest possible coercive field strength are usually used to prevent this. Often, alloys with constituents or fractions of rare earth elements are used to achieve the highest possible coercive field strength. Particularly so-called heavy rare earth elements such as terbium and dysprosium have a high coercive force and therefore offer themselves to stabilize the permanent magnets. However, these materials are rare and costly.

Specifically, the invention relates to an electric machine, in particular an electric motor having a stator and a rotor rotatably mounted about a rotor axis with a rotor body, in recordings of the rotor body, which extend from a radially inner end along its respective longitudinal axis to a radially outer At least two permanent magnets in the form of partial magnets are arranged, of which a first belongs to a first set of permanent magnets and a second to a second set of permanent magnets and wherein the permanent magnets of the first set of the permanent magnets of the second set with respect to the material Composition, in particular with respect to the magnetic properties differ. It can also be provided that at least two permanent magnets in the form of partial magnets are arranged within the receptacles, of which a first belongs to a first set of permanent magnets and a second to a second set of permanent magnets.

The invention has for its object to provide an electric machine of the type mentioned, on the one hand is inexpensive to produce and should be executed stable and reliable. In addition, the machine should have as high as possible a high demagnetization strength at a high achievable power density.

The object is achieved with the features of the invention in that at least one permanent magnet of the first or second quantity or at least one composite body with two permanent magnets of the first quantity or the second quantity or a composite body with a permanent magnet of the first quantity and a permanent magnet of the second quantity Contour, whose cross-sectional area lying perpendicular to the longitudinal axis is reduced at least partially within the respective receptacle to its radially outer end.

In the machine according to the invention permanent magnets of different composition can be used, which consist for example of materials with different coercive forces. Thus, in the region of the rotor in which the permanent magnets are exposed to increased disturbing magnetic field strengths, materials with higher coercive forces can be used, while in other areas of the rotor materials with lower coercive field strength and, for example, a higher magnetic remanence can be used. In particular, the invention offers the possibility of inserting two permanent magnets of different composition within a receptacle of the rotor, in which case the material with higher coercive field strength can preferably be used in the region of the receptacle and the rotor which is closest to the rotor gap and thus increased Is exposed to interference magnetic fields. Within a receptacle, two or three, four or even more permanent magnets of the first quantity and optionally also one or more permanent magnets of the second quantity may be arranged. These partial magnets can be connected to each other by conventional joining techniques such as gluing, soldering, welding or positive connection or even just inserted together in a receptacle and there jammed or wedged.

Basically, in the case of the electric machine, the design of an inner rotor can be provided, so that a central rotor with centrifugal forces acting radially outwards relative to the magnetic gap is present. However, it can also be provided an outer rotor, are directed away at the corresponding fly forces away from the rotor to the outside and thus also from the inneliegenden stator.

In principle, the receptacles in the rotor or at least some of the receptacles, in particular those receptacles in which a plurality of permanent magnets are arranged, as seen in the cross section of the rotor with their respective longitudinal axes spoke-like away from the rotor axis to the outside. However, other arrangements of the receptacles in the rotor body are conceivable, for example a V-shaped arrangement of the longitudinal axes of the receptacles for pairs of permanent magnets. The individual legs of the respective V-arrangements do not extend radially toward the rotor axis in this case, but at an angle to the radial direction, while nevertheless providing a region of the respective receptacle located radially further inwards and a region of the receptacle lying radially further outward.

Furthermore, the invention provides that the or some of the permanent magnets each have a contour that allows an at least partially positive fixing within the respective receptacle ("partially" means in this context, for example: exclusively against radially acting centrifugal forces). The prior art has cuboid permanent magnets, which are received in correspondingly shaped recesses of the rotor body, wherein in the radially outer region of the magnetic gap on the rotor body projecting lugs are formed to hold the respective permanent magnet in the receptacle. The receptacles of the rotor body are preferably open to the magnetic gap so that at least in the presence of an inner rotor at high speeds and correspondingly large-acting centrifugal forces, the permanent magnets are pressed outward against the lugs of the rotor body. Since the magnetic gap is usually kept small in order to increase the efficiency of an electric machine, the thickness of the projections of the rotor body which are to hold the permanent magnets is limited and these can break during operation.

The inventive design of the permanent magnets allows a better distribution of the centrifugal forces on the edge surfaces of the recordings and corresponding approaches to the rotor body for the retention of the permanent magnets can be omitted in particular entirely. This results in a higher reliability of the electrical machine and in addition, the power density can be increased, in that the permanent magnets extend directly to the cylindrical outer surface of the rotor and can be aligned with this, for example.

An advantageous embodiment of the invention is achieved in that the permanent magnets and / or composed of two or more permanent magnets composite body whose cross-section is reduced to the radially outer end of a receptacle towards at least partially, at least at its radially outer end, in particular with their entire outer contour, mating fit with the respective recording.

Due to the fact that a permanent magnet and / or a composite body abut against the edge of the receptacle (s) at least in the region of its radially outer end, ie where corresponding retention forces of the rotor body are required due to acting radial centrifugal forces, ensures that leads to a distribution of the compressive forces and thus the radially outer edge surfaces of the recess (s) loaded in the rotor body only to the reasonable extent. The positive matching of a permanent magnet / composite body with the respective receptacle is already achieved when in the radial direction of the respective body rests at least on a partial surface on a corresponding complementarily shaped contact surface in the edge region of the receptacle. The distribution of force is, of course, the better, the larger the contact surface, that is, the farther the range extends, in which the permanent magnet mates with the edge of the recording form fit.

In particular, the permanent magnet / composite body can be completely positively fitted into a corresponding receptacle of the rotor body.

This can for example be achieved in whole or in part by the fact that the permanent magnet / composite body is composed of several partial bodies within the receptacle of the rotor body or is produced within the receptacle by pressing or casting.

Particularly advantageously, the invention can be applied to an electrical machine, i. a rotor or a generator are applied, when the rotor is formed as an inner rotor and surrounded by a stator.

In this case, the rotor forms a solid cylindrical body in which the corresponding space is present in order to arrange and align the receptacles for permanent magnets optimized.

Regardless of this optimized design, the invention is equally applicable to electric machines having an outer rotor / outer rotor.

A further advantageous embodiment of the invention provides that one or more permanent magnets of the first or second quantity or one or more composite bodies in the cross section of the rotor have a barrel-shaped contour or a radially outwardly acute tapering contour. Overall, the contour of the permanent magnets / composite bodies tapering in the cross-section perpendicular to the rotor axis and tapering radially outwards can be realized in various ways. Such a shape can be realized for example by a circular or oval contour of a permanent magnet or a composite body or by a barrel-shaped structure or by a substantially triangular or trapezoidal structure, wherein at least partially an area tapering radially outwards is provided. In the case of a composite body consisting of two or more individual bodies, a single body of this body can be tapered in sections corresponding to radially outwards, or even several bodies or all bodies. For example, in the radial direction two or more round or oval in cross-section permanent magnets are lined up one behind the other and connected to each other or only abut each other. The term composite body is to be understood in the sense that an entire body can consist of several individual bodies which are either connected to each other or arranged directly adjacent to each other and touching each other. A composite body may also be understood as a body which is composed of several different bodies or mixed in sections of a plurality of different substances. In this case, the proportions of different bodies can have different material compositions and, for example, different coercive field strengths and / or different magnetic remanences.

The invention can also be advantageously realized in that one or more permanent magnets or composite bodies have / have a step-shaped cross-sectional widening towards the radially inner end of the respective receptacle.

Also, by such a step which is provided on a body or between two bodies in the transition region, a corresponding contact surface can form-fit to the corresponding edge surface of a receptacle on which the step is applied, are created. A further advantageous embodiment of the invention provides that a composite body having a radially further outward and a radially inner permanent magnet and that each radially further inside permanent magnet has a larger cross-sectional area at the joint between the two permanent magnets, as in the same area each radially further outward permanent magnet.

In this case, the radially further inner and the radially further outer permanent magnet are advantageously connected to each other, so that the form-fitting held radially inner permanent magnet by its connection with the outer permanent magnet keeps this when centrifugal forces occur.

Furthermore, it can be advantageously provided that the radially outer permanent magnet has a higher coercive field strength than the radially inner part of the permanent magnet / composite body. As a result, the radially outer permanent magnet, which tends to be exposed to higher magnetic interference fields in the region of the magnetic gap of the electric machine, has a high stability against demagnetization by such interference magnetic fields than the radially inner part. This should apply especially at higher temperatures, for example, above 120 ° C.

In this case, it may also be advantageously provided that at least two assembled permanent magnets of at least one composite body have mutually parallel magnetization directions.

In this case, different course configurations of the magnetic flux are conceivable overall in the rotor body, wherein the positive properties can be well combined with different permanent magnets within a receptacle if their magnetization directions are parallel to one another. Overall, a V-shaped arrangement of respective pairs of permanent magnets and / or composite bodies can be provided in the rotor body. Typically, several such V-shaped arrangements are distributed around the circumference of a rotor. A V-shaped arrangement consists of two receptacles within the rotor body which form the individual legs of a V in the cross section of the rotor and each receive one or more permanent magnets and / or composite bodies. The individual legs of the V-shaped arrangement need not be formed as a straight line limited grooves, but they can positively each barrel-shaped permanent magnets or successively lined up groups of permanent magnets / composites record, which in turn can be individually barrel-shaped, circular in cross-section or trapezoidal or similar ,

By virtue of such a V-shaped design, optimized magnetic flux properties are achieved in the rotor body, with a higher total magnetic flux and thus a higher energy density overall being achieved for the electric machine by a convex design of the individual legs of the Vs or by the convex design of sections of the respective Vs can be.

The individual permanent magnets and / or composite bodies can advantageously be provided within the rotor in groups in each case in a Halbach arrangement as components of a magnetic circuit.

With the known Halbachanordnung of magnets can be realized on one side of a number of magnets a much higher field strength than on the corresponding opposite side of the magnets. The Halbach arrangement is arranged in the present case in the circumferential direction of a rotor such that the side of the greater field strength is turned to the magnetic gap of the machine. To create a Halbach arrangement, various types of magnets, in particular of a first quantity, a second quantity and a third quantity of magnets, can be combined with each other A further advantageous embodiment of the invention provides that the first set of permanent magnets has a lower mass fraction of rare earth than the second set, in particular no share of rare earths.

In this case, the fact can advantageously be exploited that compared to materials which do not contain rare earths, such materials with rare earth portions usually can have an increased coercive field strength and on the other hand also or alternatively a particularly high remanence.

In this case, a high coercive field strength can be achieved, in particular with a mass fraction of so-called heavy rare earths, i. when using the elements ytrium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and / or lutetium. Light rare earths such as scandium, landan, cerium, praseodymium, neodymium, promethium, semarium and / or europium tend to be more likely to increase remanence. In principle, however, it may be advantageous to use as few or no mass fractions of heavy rare earths, in particular with mass fractions below 1%. The mass fraction of light rare earths can advantageously be in a range between 5 and 25%, more advantageously in a range between 10 and 20%.

Advantageously, it can also be provided that the first set of permanent magnets does not contain rare earths, and that the second set of permanent magnets has light rare earths at least in portions. It can be advantageously provided that the permanent magnets from the second set of permanent magnets preferably further away from the magnetic gap of the electric machine are used as the permanent magnets of the first set or all the permanent magnets of the second set radially from the magnetic gap farther than the permanent magnets of the first Amount.

By means of the described measures it is achieved that, on the one hand, the permanent magnets, which are closer to the magnetic gap, are made of a material with a higher coercive force. field strength and low magnetic remanence are produced as the permanent magnets, which have a greater distance to the magnetic gap.

A further advantageous development of the invention consists in that the rotor body additionally has pockets with permanent magnets of a third quantity, the permanent magnets of the third quantity differing from the permanent magnets of the first and second quantities with respect to the material composition, in particular the magnetic properties, and in particular are each arranged symmetrically between the receptacles that receive the permanent magnets of the first and second quantities.

The permanent magnets of the third set are advantageously arranged symmetrically between the spokes, for example, in a spoke-like arrangement symmetrically constructed around the rotor axis of the rotor, or in the case of V-shaped configurations of pairs of permanent magnets or permanent magnet groups, the permanent magnets of the third set be arranged centrally between the legs of the V-shape. The material composition of the permanent magnets of the third quantity differs from the composition of the permanent magnets / composite bodies of the first and second quantity, wherein the composition of the first and the second quantity may also be equal to one another. The magnetization direction of the permanent magnets of the third set is advantageously rotated within the cross-sectional plane of the rotor by an angle range between 60 ° and 120 ° to the magnetization direction of the permanent magnets of the first and second group, advantageously perpendicular to the magnetization direction of the permanent magnets of the first and second group and / or in the radial direction aligned with the rotor body. In this way, the permanent magnets of the third set can optimize the design of the magnetic flux profile in the rotor body and thus further increase the power density of the electrical machine and / or contribute to the formation of a Halbach arrangement.

In particular, the permanent magnets of the third set are each arranged in a closed recess / pocket of the rotor body. Embodiments of the invention will be explained in more detail with reference to a drawing. Show:

1 in cross section a rotor and a part of a stator of an electric motor,

2 shows a further rotor of an electric motor in cross section,

3 shows in a cross section a permanent magnet configuration,

FIGS. 4-11 in cross section further permanent magnet configurations,

12 in cross-section another rotor of an electric motor,

13 shows in a further cross-section a further rotor of an electric motor with barrel-shaped in cross-section permanent magnet, Fig. 14 is a diagram with parameters of magnetic materials,

15 in cross-section an external rotor and an inner stator of an external rotor motor,

Fig. 16 in cross section a section of a further rotor of a

Electric motor,

17 is a partial cross-sectional view of part of a rotor and a stator of an electric motor, wherein two permanent magnets are shown in a V-configuration,

18 is a schematic cross section of a rotor of an electric motor, wherein the permanent magnets are arranged in V-configurations,

Fig. 19 partially a cross section of a rotor and a stator of a

Electric motor with permanent magnets in V-configuration,

20 shows an arrangement as shown in FIG. 19 with a double-trapezoidal shaped permanent magnet in cross-section, FIG.

21 is a cross section of a rotor with tonnenformig in cross-section permanent magnet in spoke arrangement,

Fig. 22 is a rolled-up view of a rotor with barrel-shaped in cross-section permanent magnet and

FIG. 23 is an unrolled view of a cross section of a rotor of FIG

Electric motor similar to FIG. 22, with the cross-sectionally shaped permanent magnets are in two parts barrel-shaped.

1 shows a rotor 1 of an electric motor, which is rotatably mounted within a stator 2 about a rotor axis 3. It is visible in the cross-section of FIG. 1 that six permanent magnets 5, 6 are held within receptacles 5a, 6a within the rotor body 4, the longitudinal axes 7 of the receptacles being aligned radially with respect to the rotor axis 3. It is in such a construction is a so-called spoke-like arrangement of the permanent magnets. The magnetic gap 8 is shown exaggerated in FIG. It is formed between the stator and the cylindrical outer surface of the rotor 1.

In order to achieve a particularly high efficiency of a corresponding electric motor is sought to make the magnetic gap 8 / rotor gap as small as possible.

The permanent magnets 5, 6 are not quite up to the cylindrical outer surface of the rotor 1, since they are retained by lugs 9, 10 of the rotor body in the region of the radially outer part of the receptacles 5a, 6a in these. In particular, in the case of rapid rotation, centrifugal forces act radially outward on the permanent magnets 5, 6, so that the lugs 9, 10, which hold each individual one of the permanent magnets, are subjected to considerable forces.

Fig. 2 shows a constellation of a rotor 1 'and a stator 2', wherein in the stator 2 'in cross-section so-called stator teeth 11, 12 are shown, each carrying electric windings 15, 16 in lying between them Statornuten 13, 14. The windings 15, 16 are acted upon by a drive electronics, not shown, for generating a rotating electric field with a time-varying current.

The rotor 1 'carries in recordings each spoke-like on the rotor axis 3 aligned permanent magnets 5', 6 ', which are each divided into two in the radial direction and are each formed as a composite body with a first partial magnet 17 and a second partial magnet 18. The permanent magnets 5 ', 6' can For example, by means of approaches as shown in Fig. 1 and there designated 9, 10 are retained in the recordings or held in these by known joining techniques such as gluing, soldering, welding, clamping or a positive connection. The permanent magnets 5 ', 6' extend radially to the cylindrical outer surface of the rotor and close with this flush.

It may be provided that the partial magnet 17 located radially further outwards in the respective receptacle is formed from a first set of permanent magnets each as a ferrite component or with a proportion of ferrite materials, whereas the part magnet 18 lying radially further inward forms a second quantity of Permanent magnet belongs, consists of a material containing rare earths. This partial magnet advantageously contains predominantly light rare earths, in particular a higher proportion of light rare earths than heavy rare earths, furthermore advantageously no proportion of heavy rare earths.

By the described constellation it is achieved that the permanent magnet constellation as a whole in the area in which the greatest magnetic field strengths act, i. in the vicinity of the magnetic gap, consist of a ferrite, which is inexpensive and has a sufficient coercive force, while the high magnetic remanence of rare earth materials is exploited in those partial magnets 18, which are located radially further inside and away from disturbing magnetic fields. In this way, it is prevented that a demagnetization takes place in the region of the magnetic gap, wherein a total of a minimum proportion of rare earth materials is used.

For further advantageous design of the magnetic fields within the rotor / rotor body is provided according to FIG. 2 that further permanent magnets 19, 20 of a third set of permanent magnets are each inserted between two spoke-like adjacent permanent magnet constellations. The possible magnetic field or magnetic flux constellations achieved thereby, for example Halbach arrangements, will be discussed in more detail below. 3 to 11 denote in cross-section Permanentmagnetkonstellationen with 2 permanent magnets, each having a first partial magnet in the respective upper region of the representation and a second partial magnet in the respective lower region of the representation. Basically, the figures are arranged so that the lower portion of the representation of the rotor axis of a rotor of an electromagnet is further than the upper portion. The corresponding permanent magnet constellations can be used in a spoke-like arrangement with respect to the rotor axis, however, a so-called V-shaped constellation of permanent magnets is conceivable, which will be discussed in more detail below. The respective permanent magnet constellations are advantageously accommodated in receptacles of a rotor body, which are advantageously designed with positive locking in relation to the permanent magnet constellations, ie, surround the permanent magnet constellations without gaps. However, it can also be provided that the receptacles surround the respective magnetic constellations in a form-fitting manner only in partial regions, for example in each case in the regions in which the cross section of the permanent magnet constellation is reduced in the direction radially outward.

In FIG. 3, the rotor axis 3 is shown by way of example above the permanent magnet constellation. The cross section of both partial magnets 17, 18 is rectangular and equal in size, so that the entire magnetic constellation is formed rectangular with constant cross section. The magnetization directions 21, 22 of the two partial magnets 17, 18 are indicated by arrows as in all other permanent magnet constellations of FIGS. 3 to 11 as well.

In FIG. 4, in the radially inner partial magnet 17 ', a rectangular extension 23 is provided in the radially inner region, by means of which the magnetic constellation is held in the receptacle with radially acting centrifugal forces. In principle, it should be noted that according to FIGS. 3, 4, 5, 6, 7 and 11, the radially inner partial magnet of the magnet constellation is designed to be longer in the radial direction than the radially outer partial magnet. According to FIGS. 8, 9 and 10, the division is reversed, so that there the radially inner partial magnet is shorter in the radial direction than the radially outer partial magnet. 5 shows a trapezoidal cross-section of the radially inner part magnet 24, wherein the trapezoid tapers radially outward. The radially outer partial magnet 18 "is rectangular.

Fig. 6 shows radially inwardly a partial magnet 25 with a rectangular extension 23 ', wherein the radially outer partial magnet 26 in cross-section trapezoidal, extending radially outward, is formed.

Fig. 7 shows the radially inner part of the magnet 24 'in cross section in trapezoidal formation radially tapering outward, wherein the radially outer part magnet 26' as a trapezoid, as shown in Fig. 6, is formed tapering radially inwardly.

All constellations shown in FIGS. 4 to 7 have undercuts which reliably prevent radial outward slipping out of a correspondingly shaped receptacle in a rotor body.

FIG. 8 shows a cross-section of a rectangular magnet constellation, with the radially inner partial magnet 27 having a smaller extent in the radial direction than the partial magnet 28 lying radially on the outside.

The magnetic constellation of FIG. 9 shows in cross-section a rectangular radially inner partial magnet 27 ', wherein the radially outer partial magnet 29 is trapezoidal in cross-section and tapers radially outward with respect to the rotor axis 3.

According to FIG. 10, both partial magnets 29 'and 30 are trapezoidal in cross-section, the trapezoids each tapering radially outward with respect to the rotor. In addition, a shoulder 31 is formed between the partial magnet 29 'and the partial magnet 30 at the joining surface in that the smaller top surface of the trapezoidal shape of the partial magnet 30 is larger than the larger top surface of the trapezoidal cross-sectional shape of the partial magnet 29'. At the transition or at the joint between the radially inner partial magnet 30 and the radially outer partial magnet 29 'is thus provided a sudden reduction in the cross-sectional area.

11 shows a cross-sectional constellation in which the radially inner partial magnet 32 is rectangular and the radially outer partial magnet 33 is trapezoidal in shape, with the trapezoidal cross section of the radially outer partial magnet 33 tapering radially outward.

The constellations shown in FIGS. 9, 10 and 11, as well as the constellations shown in FIGS. 4, 5, 6 and 7, have a cross-sectional reduction from radially inward to radially outward, respectively retaining in a correspondingly shaped receptacle a rotor body causes.

In addition to the constellations shown in FIGS. 3 to 11, of course, other cross-sectional constellations are conceivable in which, for example, the boundary surfaces of the respective illustrated rectangles and trapezoids can be replaced by convex or concave, for example also part-spherical and barrel-shaped boundary lines.

FIG. 12 shows, for example, in cross-section a rotor of an electric motor with permanent magnet constellations / composite bodies arranged in the form of spokes, wherein each one of the permanent magnet constellations consists of two partial magnets 34, 35 which are circular in cross-section, the partial magnet 35 arranged radially on the outside each having a smaller diameter in cross section However, it can also be provided that each of the externally arranged part magnet has a larger diameter than the radially inner part magnet each seen in cross section. A retention in correspondingly shaped recordings of the magnet constellations is already given by the circular cross-sectional shape. Here, too, preferably the radially outer partial magnet 35 made of a ferrite or ferrite-containing material and the radially inner partial magnet 34 either likewise consist of a ferrite material or of a rare earth-containing material or of a mixture of the two materials. Likewise, the partial magnets of the radially inner group 34 may consist of a different material than the radially outer partial magnets 35.

13 shows in cross-section a permanent magnet arrangement of a rotor with barrel-shaped permanent magnets 36, 37 in cross section. It is indicated that the magnetization, which is indicated by azimuthally oriented arrows 38, respectively arranged at two adjacent exceptions permanent magnets 36, 37th is directed opposite.

The barrel-shaped cross-sectional shape of the permanent magnets 36, 37 caused by their undercut in the radial direction also a retention in correspondingly shaped recordings of the rotor body. Therefore, projections 9, 10 as shown in FIG. 1 can be completely omitted and the permanent magnets and composite bodies 34, 35, 36, 37 can reach as far as the cylindrical outer surface of the rotor. Thus, a small distance of the permanent magnets to the stator and thus a high efficiency of the electric machine or a high power density is achieved or achievable.

FIG. 15 shows a constellation with an inner stator 39 and an outer rotor in the form of a hollow-cylindrical rotor 40 in order to round off the invention. The rotor axis is designated 3 and the rotor 40 is rotatably mounted about the rotor axis 3.

Within the rotor body are permanent magnets 41, 42 are shown, which are aligned in a spoke-like arrangement on the rotor axis 3 and tapering radially outward in cross-section. The recordings in which the permanent magnets 41, 42 are included are designed in a form-fitting manner. It should be clarified with reference to FIG. 14 that, especially when using special geometric constellations of permanent magnets, as shown in the figures of this application, in addition to the use of different materials for the partial magnets of a single rotor, in particular the use of different materials for Various partial magnets of a composite body can be reduced by suitable choice of material and the number of different materials used for the permanent magnets used in a rotor. In this case, particularly suitable materials are those which consist of a mixed material, the mixture being set in such a way that the mixing material has a remanence field strength Br between 0.6 Tesla and 1 Tesla. Alternatively or additionally, the mixed material may have the property that the coercive force Hcj is between 1300 and 2500 kA / m. When using such a material, in particular when permanent magnets in the form of composite bodies are used, advantageously two or more partial magnets of a composite body can consist of the abovementioned material. This material then has the same composition and the same physical properties in the radially inner region of the rotor as in the radially outer part of the composite body and thus also in the magnetic gap-near region the same composition as in the magnetic gap-distant region. Such materials can be produced, for example, from ferrite and ferrite-like materials, in particular with the addition of rare earth metals, these mixed materials advantageously being free from heavy rare earth materials. Overall, the use of rare earths in permanent magnets in a rotor can thus be reduced. The required or advantageous values for the remanence field strength and the coercive field strength can be achieved with such a material. In Fig. 14, with the first hatched area 43, a substance of the class Nd / Dy / Th / Fe / B is represented by its values of the coercive force plotted against the temperature. It can be seen that the coercive force drops considerably in the range of a relatively high operating temperature of 180 to 200 ° Celsius of an engine. The third hatched area 45 shows the corresponding parameter range of conventional ferrites. The second hatched area 44 shows the substances used according to the invention, which are used, for example, as mi between rare earths and ferrites, where the coercivity is between that of rare earth materials and ferrites, the temperature dependence of the coercive force being much less than that of the more or less rare earth containing magnetic materials. Advantageously, a temperature dependence between -0.11 and 0 percent per Kelvin with respect to the remanence field strength Br is realized with the corresponding mixing materials. These values should be maintained between -50 ° Celsius and + 180 ° Celsius.

In addition, with respect to the coercive force Hcj, a temperature coefficient of -0.5 to +0.4 percent per Kelvin, between a temperature of -50 ° Celsius and + 180 ° Celsius, can be realized.

Corresponding mixing materials can be prepared as polymer-bound hybrids, wherein NdFeB can be mixed in powder form with a ferrite powder. In particular, since the temperature dependence of the coercive force of NdFeB is negative and that of ferrite powders is positive, a low temperature coefficient can be set by a suitable mixture. The individual powders can be prepared and used magnetically anisotropically by corresponding known processes, such as the grinding of premagnetized materials. Thereby, the magnetically diluting effect of the polymer binder can be compensated. The production and bonding of the corresponding magnetic body can take place in a strong magnetic constant field in order to achieve a corresponding orientation of anisotropic powder materials. It is also possible to form the shaping of the magnetic bodies in the receptacles of the respective rotor body by injection molding, high-pressure injection molding and other techniques.

The necessary field strengths for a corresponding performance of the electrical machines described can be achieved by the materials mentioned in particular if suitable geometric constellations of the permanent magnets are used, optionally with an optimized shaping of the individual magnets. In this connection, FIG. 16 shows, for example in cross-section, a section of a rotor of an electric motor. Machine with two permanent magnets, which are each formed as a composite body 46, 47, wherein each of the composite body 46, 47 consists of two partial magnets 48, 49 consists. The magnetization directions 50, 51 are uniform for each of the composite bodies 46, 47 and opposite to each other between the composite bodies 46, 47. The radially outer partial magnets 49 typically form permanent magnets of a first quantity, while the radially inner partial magnets 48 form permanent magnets of a second quantity. The material composition of the permanent magnets of the first and the second amount may be the same or different. In addition, a permanent magnet 52 of a third set of permanent magnets can be seen in FIG. 16, this last-mentioned permanent magnet 52 having a trapezoidal shape in cross-section, which tapers to the radially inner region of the rotor. The magnetization direction 53 of the permanent magnet 52 is directed radially outward.

The permanent magnets shown in FIG. 6 form a typical section of a Halbach constellation of permanent magnets, which generates a particularly strong flux concentration on one side of a magnetic constellation, ie typically in the region of the magnetic gap. Between each two spoke-like arranged Kompositkörpern 46,47, which are each formed as a two magnets 48, 49 composed permanent magnets, a permanent magnet 52 is provided in a corresponding pocket 52a.

Fig. 17 shows in cross-section a permanent magnet constellation with two permanent magnets 54, 55 in V-arrangement, which are arranged in corresponding V-shaped, matching recesses 55 a. The permanent magnets 54, 55 each form a leg of an imaginary V, wherein the permanent magnets 54, 55 do not run with their longitudinal axes on the rotor axis. Rather, the longitudinal axes of the permanent magnets intersect at a point that is radially away from the rotor axis. The constellation of such a so-called V-shaped arrangement of permanent magnets is shown schematically in the overview in FIG. 18. There are four pairs of V-shaped permanent magnets 54, 55 and the corresponding the magnetization directions 56 shown. In FIG. 17, to clarify the design of the magnetic flux, the field lines between the permanent magnets 54, 55 are shown. The V-shaped arrangement of the permanent magnets 54, 55 results in an optimal field density in the region of the magnetic gap between the rotor and stator.

The individual permanent magnets 54, 55 may also be divided in their longitudinal direction and each consist of two partial magnets as indicated by the dashed line in the permanent magnet 55 and the designation of the radially inner partial magnet by the reference numeral 57. However, it is also possible for all permanent magnets to consist homogeneously of a single material. The permanent magnets / composite bodies 54, 55, which are arranged in a V-shape and may consist of a plurality of partial magnets, may also be assembled in the manner of the constellations illustrated in FIGS. Incidentally, in FIG. 17, the magnetization direction of the permanent magnets is indicated by the arrows 58, 59.

FIG. 19 shows a similar constellation in cross-section as in FIG. 17, wherein, however, the individual permanent magnets 54 ', 55' are barrel-shaped or oval in cross-section. This results in a good retention in correspondingly shaped receptacles 55'a of the rotor body and a further optimized field design as will be explained in more detail below with reference to FIGS. 22, 23. Also, the permanent magnets shown in Figure 19 may consist of a plurality of partial magnets of a first and second set of permanent magnets.

20 shows a representation corresponding to FIGS. 17 and 19, wherein the permanent magnets 54 ", 55" are composed in cross section of two trapezoidal quadrilaterals, the bases of which adjoin one another, wherein the individual trapezoidal bodies are connected in one piece or can also respectively represent partial magnets, which are assembled into a composite body. The magnetization directions are indicated in FIGS. 17 and 19 in the form of arrows.

Instead of the illustrated two trapezoidal bodies, two part-magnets which are barrel-shaped in cross-section, a radially inner and a radially outer part body, can either together be connected to each other or at least adjoin one another to form a composite body.

FIG. 21 shows by way of example a so-called Halbach arrangement of magnets, the individual partial magnets 60, 61, 62, 63, 64, 65, 66 of the Halbach arrangement being lined up in the circumferential direction. In principle, spoke-like arranged permanent magnets 60, 61, 62, 63 are provided, wherein a first pair 60, 61 has magnetization directions, which are directed towards each other, represented in FIG. 21 by arrows. The adjacent pair of permanent magnets 62, 63 also have directions of magnetization directed toward each other, with the directions of magnetization of the permanent magnets 61 and 62 being directed in opposite directions and away from each other.

The respective further permanent magnets 64, 65, 66 arranged between adjacent permanent magnets each have, in the circumferential direction, an alternately radially outwardly and radially inwardly directed magnetization direction. By this overall constellation, the magnetic flux radially inward with respect to the permanent magnets 60, 61, 62, 63 is minimized and the magnetic flux radially outward of the magnets is maximized. This results in the region of the magnetic gap between the stator and rotor an optimized magnetic field strength.

In addition to the optimized arrangement and orientation of the permanent magnets, the magnetic field strength or the flux can also be optimized by the outer shape of the individual permanent magnets. For clarification, FIG. 22 shows a linearly unrolled constellation of two permanent magnets 60, 61 located next to each other in a cylindrical rotor. A closer look at the magnetic and physical conditions reveals that the remanence field strength of such an arrangement decreases with decreasing distance between the magnets. Manentmagnete in Azimutalrichtung, indicated by the arrow 67 increases, and with the expansion of the individual permanent magnets in the azimuthal direction. In addition, the flux density can be increased by increasing the area on which flux lines emerge or enter from the respective permanent magnet in the azimuthal direction. Thus, in the variant illustrated in FIG. 23, the double-barrel-shaped configuration of the permanent magnets 60 ', 61' results in an even higher flux density than in the constellation according to FIG. 22.

The measures individually described in the above examples for increasing the flux density within the rotor body or for designing the overall magnetic flux are to be understood as measures which can be combined with one another to design an optimized rotor adapted to the respective requirements. Thus, an electric machine can be created according to the invention, which allows for the lowest possible use of rare earth elements to achieve high power density and high torques of an electric machine.

LIST OF REFERENCE NUMBERS

1, V rotor

2 stators

3 rotor axis

4 rotor body

5, 6 permanent magnets

5a, 6a recordings

5b, 6b radially outer ends of 5a, 6a

5c, 6c radially inner ends of 5a, 6a

7 longitudinal axis of 5a

8 magnetic gap, rotor gap

9, 10 approaches

1 1, 12 stator teeth

13, 14 stator slots

15, 16 stator windings

17, 17 'partial magnet made of ferrite

18, 18 ', 18 "partial magnet with rare earths

19, 20 permanent magnets of the third set

21, 22 magnetization directions

23, 23 'extension

24, 24 ', 25, 26, 27, 28, 29, 29', 30 partial magnet

31 approach

32, 33 partial magnet

34, 35 circular partial magnets

35a recording

36, 37 barrel-shaped permanent magnets

38 magnetization direction

39 internal stator

40 hollow cylindrical, external rotor

41, 42 permanent magnets

43 first area

44 second area third area

, 47 composite bodies

a recording

, 49 partial magnet

, 51 magnetization direction

Permanent magnet of the third Mengea bag

magnetization direction

, 54 ', 54 ", 55, 55', 55" Permanent magnets in V arrangement

'a recording

magnetization direction

solenoid

, 59 magnetization direction / arrow

, 60 ', 61, 61', 62, 63 permanent magnets in spoke arrangement, 65, 66 further permanent magnets

a bag

azimuthal

Claims

claims

1. Electrical machine, in particular electric motor with a stator (2) and a rotor axis (3) rotatably mounted rotor (1, 1 ') with a rotor body (4),

- Wherein in receptacles (5a, 6a, 35a, 47a, 55a, 55'a) of the rotor body (4), extending from a radially inner end (5c, 6c) along their respective longitudinal axis (7) to a radially further outside lying end (5b, 6b), at least two permanent magnets in the form of partial magnets (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49, 57), of which a first one (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29 ', 30, 32, 33, 34, 35, 48, 49, 57) to a first set of permanent magnets and a second one (17, 17', 18, 18 ', 18 ", 24, 24', 25, 26 , 27, 28, 29, 29 ', 30, 32, 33, 34, 35,

48, 49, 57) belongs to a second set of permanent magnets,

- wherein the permanent magnets (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27,

28, 29, 29 ', 30, 32, 33, 34, 35, 48, 49, 57) of the first set differ from the permanent magnets (17, 17', 18, 18 ', 18 ", 24, 24', 25 , 26, 27, 28,

29, 29 ', 30, 32, 33, 34, 35, 48, 49, 57) of the second amount with respect to the material composition, in particular with respect to the magnetic properties, and

- wherein at least one permanent magnet (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49 , 57) of the first or second quantity or at least one composite body (46, 47) with two permanent magnets (7, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29 ', 30, 32, 33, 34, 35, 48, 49, 57) of the first quantity or the second quantity or a composite body with a permanent magnet (17, 17', 18, 18 ', 18 ", 24, 24', 25, 26, 27, 28, 29, 29 ', 30, 32, 33, 34, 35, 48,

49, 57) of the first set and a permanent magnet (17, 17 ', 18, 18 ', 18 ", 24, 24', 25, 26, 27, 28, 29, 29 ', 30, 32, 33, 34, 35, 48, 49, 57) of the second set have a contour whose perpendicular to Longitudinal axis (7) lying cross-sectional area within the respective receptacle (5a, 6a, 35a, 47a, 55a, 55'a) to its radially further outward end (5b, 6b) towards at least partially reduced.

2. Electrical machine according to claim 1,

characterized,

in that the permanent magnets (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49, 57 ) and / or the composite bodies (47) whose cross-section is at least partially reduced towards the radially further outward end (5b, 6b) of a receptacle (5a, 6a, 35a, 47a, 55a, 55'a), at least at its radially outer end (5b, 6b), in particular with their entire outer contour, positively fit together with the respective receptacle (5a, 6a, 35a, 47a, 55a, 55'a).

3. Electrical machine according to claim 1 or 2,

characterized,

the rotor (1, 1 ') is designed as an inner rotor and is surrounded by a stator (2).

4. Electrical machine according to one of claims 1 to 3,

characterized,

in that one or more permanent magnets (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49 , 57) of the first or second quantity or one or more composite bodies (46, 47) in the cross-section of the rotor (1, 1 ') have a barrel-shaped contour or a contour tapering radially outward at an acute angle.

5. Electrical machine according to one of claims 1 to 4,

characterized,

in that one or more permanent magnets (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49 , 57) or composite bodies (47) to the radially inner end of the respective receptacle (5a, 6a, 35a, 47a, 55a, 55'a) towards a stepped cross-sectional widening / have.

6. Electrical machine according to one of claims 1 to 5,

characterized,

a composite body (47) has a radially further outward and a radially further inner permanent magnet (17, 17 ', 18, 18', 18 ", 24, 24 ',

25, 26, 27, 28, 29, 29 ', 30, 32, 33, 34, 35, 48, 49, 57) and that the respective radially further inwardly located permanent magnet (17, 17', 24, 24 ' 25, 27, 27 '30, 32) at the joint between the two permanent magnets (17, 17', 18, 18 ', 18 ", 24, 24', 25, 26, 27, 28, 29, 29 ', 30th , 32, 33, 34, 35, 48, 49, 57) has a larger cross-sectional area than in the same area of the respectively radially outer permanent magnet (18, 18 ', 18 ",

26, 26 ', 28, 29, 29', 33).

Electric machine according to one of claims 1 to 6,

characterized,

that in each case two joined permanent magnets (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49 , 57) of at least one composite body mutually parallel magnetization directions (21, 22, 38, 50, 5153, 56, 58, 59).

Electric machine according to one of claims 1 to 7,

characterized,

in that the permanent magnets (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49, 57 ) and / or composite bodies (47) are part of a V-shaped arrangement of components of a magnetic circuit.

9. Electrical machine according to one of claims 1 to 8,

characterized,

in that the permanent magnets (17, 7 ', 18, 8', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49, 57 ) and / or composite bodies (46, 47) Part of a Halbach arrangement of components of a magnetic circuit.

Electric machine according to one of claims 1 to 9,

characterized,

the first set of permanent magnets has a lower mass fraction of rare earths than the second set, in particular no share of rare earths.

11. Electrical machine according to one of claims 1 to 10,

characterized,

that the second set of permanent magnets has a mass fraction of light rare earth elements and that the mass fraction of heavy rare earth elements is less than the proportion of light rare earth elements, in particular that the mass fraction of heavy rare earth elements is zero ,

12. Electrical machine according to one of claims 1 to 11,

characterized,

in that the rotor body (4) additionally has pockets (52a, 64a) with permanent magnets (19, 20, 52, 64, 65, 66, 68) of a third quantity, the permanent magnets (19, 20, 52, 64, 65, 66 , 68) of the third set, in particular of the permanent magnets (17, 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34 , 35, 48, 49, 57) of the first and the second quantity differ with regard to the material composition and in particular are arranged in each case symmetrically between the receptacles (5a, 6a, 35a, 47a, 55a, 55'a) which hold the permanent magnets (17 , 17 ', 18, 18', 18 ", 24, 24 ', 25, 26, 27, 28, 29, 29', 30, 32, 33, 34, 35, 48, 49, 57) of the first and second Record quantity.