DE102005048731A1 - Permanent magnet rotor for an electric motor has a laminated yoke with radially aligned retaining overhangs extending in the yoke's axial direction - Google Patents

Abstract

Retaining overhangs each have a recess (19) that extends in an axial direction and is limited in a permanent magnet rotor's (10) direction of circumference by retaining sections (21), which are pre-stressed to sit close to permanent magnets (18) in the rotor's lateral surface plane and to fix the magnets in retaining spaces. An independent claim is also included for a method for fitting permanent magnets on a permanent magnet rotor.

Description

The The invention relates to a permanent magnet rotor according to the preamble of claim 1 and a method for assembling permanent magnets on a permanent magnet rotor.

Permanent magnet Synchronous machines are taking advantage of numerous applications the regenerative or motor operation already since prolonged well known. During motor operation, the magnetic field occurs the on a peripheral surface of the rotor arranged plurality of permanent magnets with a in the stator generated magnetic field in interaction. This is going on the rotor exerted a torque, which this rotationally accelerated and synchronous to the stator magnetic field drives.

The Permanent magnets are extraordinary at high rotor speeds Exposed to stress, which due to the centrifugal forces and as a result the brittleness common Magnetic materials, for example. NdFeB, on the one hand in electrical internal rotor machines to dissolve the permanent magnet poles from their support structure on the rotor and on the other hand to breakage can lead.

The recoverable torque of an electrical machine is known to hang much of the width of the radial air gap between the rotor arranged permanent magnets and the stator poles, said this To achieve a high efficiency as narrow as possible to dimension is. The structural design of the magnetic support structure comes thus with regard to operational safety and efficiency one Such machine has enormous significance.

at a direct arrangement of a plurality of permanent magnets on the outer peripheral surface of a Rotor yoke has the problem that it hardly due to manufacturing tolerances possible is, these permanent magnets mainly positive and without further assembly elements or additives in a predetermined to arrange reproducible and reliable position on the rotor yoke.

To circumvent this difficulty beats the DE 202 01 831 U1 a rotor, wherein on the outer peripheral surface of dovetail-shaped recesses for receiving trapezoidal permanent magnets are executed and wherein the recesses in a base region and two adjacent inclined lateral surfaces a total of three resilient or elastic plates which on the rotor axis directed to the base surface and the adjacent Side surfaces of a Permanenetmagneten frictionally abut. When a permanent magnet is inserted axially into a receptacle, the elastic or resilient plates are deformed in the axial direction so as to fix the permanent magnet resiliently but also permanently. By an elastic deformation of the laminated core, the recesses of the permanent magnets are increased, thereby ensuring that a permanent magnet can be inserted without damaging it in its recording and firmly recorded.

The explained Arrangement guaranteed Although a secure recording of a magnetic element, but occurs on the other hand by the axial deformation of the laminated core already during the Mounting a significant damage the one to the leadership of the magnetic flux required lamellar structure, wherein the mutually insulated laminations electrically shorted become and from which losses for the magnetic circuit formed between the rotor and stator and unwanted eddy currents result. Especially can when operating the electrical machine, the eddy currents to one high warming lead the rotor and the permanent magnets, causing their magnetization can be lifted.

The DE 39 13 618 C2 discloses another generic permanent magnet rotor in which a plurality of retaining projections extend radially outwardly from a yoke which is fixed to the outer periphery of a rotor shaft, wherein the retaining projections extend in the axial direction of the yoke and increases its width at the radially outer ends in the circumferential direction of the yoke and wherein a plurality of permanent magnets are each disposed between adjacent retaining projections and secured between them. In this case remain between at least a portion of the circumferential surfaces of the permanent magnets and the opposing surfaces of the yoke including the holding projections fixedly connected thereto adhesive gaps, in which a layer of thermosetting synthetic resin is filled and whereby the permanent magnets are held in a constant position with respect to the rotor shaft and the yoke should.

at such a fastening of the magnets is the problem that Nevertheless, at high speeds and thermal cycling permanent magnets detach from their resin base and change their radial position on the rotor can.

The object of the invention is starting from the prior art, a rotor for a To provide permanently magnetically excited electric machine to which a plurality of permanent magnets can be reproducibly and reliably secured, in particular, damage to the rotor yoke is largely avoided. According to a further aspect of the invention, a method for mounting permanent magnets on a permanent magnet rotor is proposed.

The Task becomes according to the first Aspect by a generic permanent magnet rotor solved, the features specified in the characterizing part of claim 1 having.

It Thus, a permanent magnet rotor is proposed, the first one a wicked yoke with executed, radially directed retaining projections includes, which extend in the axial direction of the yoke and the width of which is at the radially free ends in the circumferential direction of the yoke is enlarged. Between adjacent holding projections are receiving spaces for Arrangement of permanent magnets arranged.

Draws according to the invention The rotor characterized by the fact that the holding projections one in the axial direction Have extending recess in the circumferential direction of the rotor is limited by two holding sections, wherein the holding sections biased in the lateral plane of the rotor to the permanent magnet abut and fix them in the receiving rooms.

On this way you can Permanent magnets fixed on a rotor for safe operation and assembly without any further fasteners or adhesives requirement. The bias of the holding portions in a lateral plane avoids damage the rotor yoke as this may be the case in the prior art. For mounting the permanent magnets, it is necessary, the holding sections For example. With the help of a mounting tool to pivot slightly from the yoke, which the permanent magnets easily inserted axially into the recesses can be. After positioning the magnets, the holding sections become again relieved, whereby this under a bias to the permanent magnets invest.

advantageous Further developments and refinements of the invention are specified in the subclaims.

According to claim 2, the assembly of the permanent magnets proves to be advantageous when the yoke remote from the ends of the holding sections between spanning a connecting section, the one at this acting force an elastic pivoting of the holding portions around a foot area allows. Preferably, this force can be substantially radially on the holding portions attack. As a result, the formed between two holding projections housing spaces expanded together to the required extent. The initiation the force can be displaced, for example, by radially directed Stamp done as part of an assembly tool for automated Assembly of the permanent magnets are, although all on a rotor yoke formed connecting portions simultaneously with a force can be applied.

According to claim 3, the rotor can be further improved by inside the recesses a securing element is arranged, which the holding sections blocked during rotation of the rotor and thus an expansion the reception rooms prevented. Advantageously, as proposed in claim 4 is, the fuse element form-fitting to the holding sections at.

In a further particularly advantageous embodiment according to claim 5, the connecting portion is formed concavely on the retaining projection. During the rotation of the rotor, both the permanent magnets are subject as well as the holding portions and connected to these connecting portions the influence of the acting centrifugal force, whereby the latter at a internal rotor radially outward be relocated and over the holding sections the contact pressure and the fixation of the permanent magnets even stronger.

According to claim 6 it is suggested that the value of the expansion coefficient a fuse element is larger as that of a permanent magnet. In this way it is ensured that at a temperature increase the holding sections in the permanent Contact with the permanent magnet remain and the holding force even increase.

to Prevention of breakage the permanent magnets it is according to claim 7 expedient protective elements to be provided which are inserted between the holding portions and the permanent magnets.

The the permanent magnets supporting retaining projections or Holding sections can according to claim 8 also by means of a plastic forming process in contact with the Permanent magnets are brought.

• – Einleiten einer Kraft auf die Verbindungsabschnitte von jeweils zwei am Umfang des Jochs benachbarten Haltevorsprüngen, wobei sich deren Halteabschnitte in der Lateralebene des Jochs verschwenken und die Aufnahmeräume vergrößern,
• – Einsetzen von Permanentmagneten in die Aufnahmeräume,
• – Entlasten der Verbindungsabschnitte von der Kraft, wodurch sich die Halteabschnitte vorgespannt an die Permanentmagnete anlegen und diese in deren Lage fixieren und ggf. nach Anspruch 10,
• – Einführen von Sicherungselementen in die Ausnehmungen der Haltevorsprünge zur Sicherung der Montageposition der Permanentmagnete.

According to the second aspect of the invention, a method for mounting permanent magnets on a permanent magnet rotor according to any one of claims 1-7 is proposed according to claim 9, comprising the following steps:

• Introducing a force onto the connecting sections of in each case two holding projections adjacent to the circumference of the yoke, the holding sections of which pivot in the lateral plane of the yoke and enlarge the receiving spaces,
• Inserting permanent magnets into the receiving spaces,
• Relieving the connecting portions of the force, whereby the holding portions biased to create the permanent magnets and fix them in their position and possibly according to claim 10,
• - Insertion of securing elements in the recesses of the retaining projections for securing the mounting position of the permanent magnets.

in the The invention will be described below by way of example with reference to the attached figures explained. Show it

1 - 4 a partial radial sectional view of a permanent magnet rotor having formed on its outer peripheral surface according to the invention structure for receiving permanent magnets during successive steps of the magnet assembly;

5 a on a rotor according to the 1 - 4 fixed permanent magnet, which is inserted by means of protective elements in the rotor yoke;

6 a permanent magnet rotor having an alternately formed retaining projection prior to magnet assembly;

7 a permanent magnet rotor after 6 with pressed retaining projections.

In the 1 - 4 is a section of a permanent magnet rotor 10 for a drawing machine not shown in internal rotor type shown, which is formed of electric plate fins circular yoke 12 includes, which here simplified, drawn in developed form. On the outer peripheral surface 14 is a plurality of identical, radially outwardly widening retaining projections 15 formed in the axial direction of the yoke 12 extend and dovetail-shaped receiving spaces between them 16 for receiving permanent magnets 18 define. It can be seen that within the retaining projections 15 a recess extending in the axial direction 19 is formed, in the circumferential direction of the rotor 10 each of two holding sections 21 is limited ( 1 ).

The recording rooms 16 each have a base area 20 on, in the circumferential direction of the rotor 10 in two radially outward, each other inclined flanks or holding surfaces 22 the retaining projections 15 passes. The permanent magnets 18 are according to the 3 . 4 designed with an isosceles-trapezoidal cross section, wherein the two parallel surfaces 26 . 28 of the trapezoid radially to the rotor 10 are arranged and coincide with the magnetic N and S pole. The pitch angle α between the base 20 and the holding surfaces 22 of the recording room 16 is in the production of the yoke 12 designed slightly smaller than the trapezoidal angle β, which is located between the base surface 28 and the inclined surfaces 30 ie the trapezoidal legs 30 spreads.

The yoke 12 opposite ends of the holding sections 21 stretch between them on the retaining projection 15 concave connecting portion 24 on, which is itself elastically deformable within certain limits with a preferably radially acting force F in the arrow direction and an elastic pivoting of the holding portions 21 around a foot area 23 allows, whereby the between each two retaining projections 15 trained recording rooms 16 to be widened ( 2 ). To enable a pivoting are in the foot area 23 to the recording rooms 16 recesses 17 intended.

For mounting the permanent magnets 18 on the permanent magnet rotor 10 First, a radial force F on the connecting portions 24 of two each on the circumference of the yoke 12 adjacent retaining projections 15 initiated, where, as in 2 shown the connecting sections 24 elastically deform radially inward and the holding sections connected thereto on both sides 21 in the plane of the yoke 12 panning away. These are the ones between the holding sections 21 located recording rooms 16 Enlarged so far, into this the permanent magnets 18 can be easily inserted axially.

When the permanent magnets 18 her predetermined position at the yoke 12 have taken the connecting sections 24 Relieved from the force F, which causes the holding sections 21 in the lateral plane of the rotor 10 resiliently biased to the inclined surfaces 30 the permanent magnets 18 can create and the latter with their base area 28 to the base 20 the reception rooms 16 Press and fix in their position ( 3 ). In this state, the pitch angle α corresponds approximately to the trapezoidal angle β. The permanent magnets 18 are in the position shown radially over the retaining projections 18 out. In addition, the holding sections 21 be equipped with extensions to the permanent magnets 18 on both sides in the area of the outer trapezoidal surface 28 at least partially to embrace.

To secure the mounting position of the permanent magnets 18 be according to 4 at the end of the assembly positive locking elements 32 in the recesses 19 the retaining projections 15 introduced, which under the influence of centrifugal force deformation of the holding sections 21 and the connecting sections 24 block and prevent unintentional release of the fixation. In addition, in any remaining wedge gaps between the permanent magnets 18 and the holding surfaces 22 an adhesive is introduced, which also for smoothing small stacking faults in the laminated core 12 serves.

In order not to adversely affect the magnetic circuit of the electric machine, the securing elements are made of a non-ferromagnetic material, for example. Of aluminum or a plastic. By choosing the thermal expansion coefficient of the fuse elements 32 can also the holding force of the permanent magnets 18 be optimized over the temperature response. When using a permanent magnet with a negative thermal expansion coefficient, eg from the material system NdFeB and a fuse element 32 with a large positive coefficient of thermal expansion, even with an increase in the rotor temperature, the attachment of the holding sections 21 at the permanent magnets 18 be strengthened and, if necessary, reinforced. However, it is sufficient if the coefficient of expansion of the security elements 32 greater than that of the permanent magnets 18 ,

Furthermore, it may, as in 5 shown, to protect the permanent magnets 18 be favorable, between the trapezoidal legs 30 and the holding sections 21 an example. Made of a plastic protective element 34 provide that of the holding sections 21 generated holding force evenly on the trapezoidal side surfaces 30 the permanent magnet 18 distributed and thus there avoid a local overload, which could lead to damage to the brittle magnetic material. The protective element 34 it can also be that of a trapezoidal surface 30 and the base area 28 a permanent magnet 18 formed around the common edge and thus the base surface 28 at least partially border.

Every permanent magnet 18 is thus in two protective elements 34 inserted, which may also be connected to each other by means of a web and thus may be present in one piece. To minimize the radial distance of the permanent magnet 18 and yoke 12 the latter has a radially raised portion 36 on, either directly or with the inclusion of an adhesive gap on the base surface 28 a permanent magnet 18 is applied.

In 6 is a section of a permanent magnet rotor 10 with alternatively designed retaining projections 15 shown, which also recesses 19 and connecting sections 24 have, wherein the holding portions 21 with the trapezoidal surfaces 30 one inserted between these permanent magnets 18 initially form interspaces, so that a permanent magnet 18 can be positioned on the yoke both from the axial and the radial direction. It can be seen that the trapezoidal permanent magnets 18 at the base 20 of the recording room 16 rest and in the radial direction a wedge gap 38 with the holding sections 21 form. The connecting sections 24 between each two holding sections 21 a retaining projection 15 are at the yoke 12 convex, ie curved radially outward executed. The retaining projections 15 are tapered at several positions, creating fabric joints 40a -E are provided for a subsequent forming operation.

After inserting the permanent magnets 18 become the connecting sections 24 from a tool 42 with one inside, in the recesses 19 directed radial force, using the fabric joints 40a -E the connecting sections 24 concave deformed and thereby in the recesses 19 be pressed into it and at the same time the holding sections 21 in the circumferential direction of the yoke 12 swivel around to the trapezoidal surfaces 30 the permanent magnets 18 to put on like this in 7 is shown.

The deformation of the connecting sections 24 takes place only up to a predetermined degree. A further deformation radially inward beyond this dimension would then lead to a lifting of the holding sections 21 from the trapezoidal surfaces 30 to lead. If the further load within the elastic limit of the retaining projections 15 can, for example, by replacing such an elastic deformation for the exchange of individual or all permanent magnets 18 the Fixage be solved and restored. Such an assembly step accordingly corresponds to that in accordance with 1 - 4 , Of course, the permanent magnets 18 like this one in 5 represented here also protective elements 34 exhibit.

In a still further embodiment of a magnetic fixing to a rotor yoke 12 can be based on the means of 6 and 7 explained example on the connection section shown there 24 be omitted and instead the at a circumferential position of the yoke 12 in pairs trained holding sections 21 directly loaded either individually or collectively by an attacking punch this, wherein the holding sections 21 biased in the lateral plane to the permanent magnets 18 create and these at the yoke 12 fix permanently. Preferably, the holding sections 21 initially radially at the yoke 12 from, wherein a deformation of a holding portion in the direction of a permanent magnet 18 via the common yoke has no or only an insignificant interaction on the respective immediately adjacent holding section result, ie that these adjacent holding sections independently on the yoke 12 can fulfill a holding function.

10

rotor

12

laminated core

14

Outer circumferential surface

15

retaining projection

16

accommodation space

17

recess

18

permanent magnet

19

recess

20

Floor space

21

holding section

22

holding surface

23

footer

24

connecting portion

26.28

parallel surface

30

trapezoidal leg

32

fuse element

34

protection element

36

sublime section

38

nip

40a-e

fabric joints

F

force

N

magnetic North Pole

S

magnetic South Pole

α, β

angle

Claims (10)

Permanent magnet rotor ( 10 ), comprising - a laminated yoke ( 12 ) with executed, radially directed holding projections ( 15 ), which in the axial direction of the yoke ( 12 ) and whose width at the radially free ends in the circumferential direction of the yoke ( 12 ) and wherein - between adjacent retaining projections ( 15 ) Recording rooms ( 16 ) for the arrangement of permanent magnets ( 18 ) are arranged, characterized in that the retaining projections ( 15 ) each have a recess extending in the axial direction ( 19 ), which in the circumferential direction of the rotor ( 10 ) of two holding sections ( 21 ), wherein the holding sections ( 21 ) in the lateral plane of the rotor ( 10 ) biased to the permanent magnet ( 18 ) and these in the reception rooms ( 16 ). Permanent magnet rotor ( 10 ) according to claim 1, characterized in that the yoke ( 12 ) facing away from the holding portions ( 21 ) between them a connecting section ( 24 ) span, which at an attacking force on this (F) te an elastic pivoting of the Halteabschnit ( 21 ) to a footer ( 23 ), whereby the between each two retaining projections ( 15 ) trained recording rooms ( 16 ) be widened. Permanent magnet rotor ( 10 ) according to claim 1 or 2, characterized in that within the recess ( 19 ) a fuse element ( 32 ) is arranged. Permanent magnet rotor ( 10 ) according to any one of claims 1-3, characterized in that the securing element ( 32 ) positively on the holding sections ( 21 ) is present. Permanent magnet rotor ( 10 ) according to one of claims 1-4, characterized in that the connecting portion ( 24 ) on the retaining projection ( 15 ) is concave. Permanent magnet rotor ( 10 ) according to any one of claims 1-5, characterized in that the value of the thermal expansion coefficient of a fuse element ( 32 ) is greater than that of a permanent magnet ( 18 ). Permanent magnet rotor ( 10 ) according to any one of claims 1-6, characterized in that the holding sections ( 21 ) with intermediate storage of protective elements ( 34 ) on the permanent magnet ( 18 ) issue. Permanent magnet rotor ( 10 ) according to any one of claims 1-7, characterized in that the permanent magnets ( 18 ) by plastically deformed holding sections ( 21 ) at the yoke ( 12 ) are fixed. Method for assembling permanent magnets ( 18 ) on a permanent magnet rotor ( 10 ) according to one of claims 2-7, comprising the following steps: - introducing a force (F) onto the connecting sections ( 24 ) of two each on the circumference of the yoke ( 12 ) adjacent retaining projections ( 15 ), wherein the holding sections ( 21 ) in the lateral plane of the yoke ( 12 ) and the receiving spaces ( 16 ), - insertion of permanent magnets ( 18 ) into the reception rooms ( 16 ), - relieving the connecting sections ( 24 ) of the force (F), whereby the holding sections ( 21 ) biased to the permanent magnets ( 18 ) and fix them in their position. Process according to claim 9, characterized records that to secure the mounting position of the permanent magnets ( 18 ) Security elements ( 32 ) into the recesses ( 19 ) of the retaining projections ( 15 ).