WO2019025193A1

WO2019025193A1 - Rotor of rotating electric machine provided with a part for holding permanent magnets in three dimensions

Info

Publication number: WO2019025193A1
Application number: PCT/EP2018/069563
Authority: WO
Inventors: Michaël HANQUEZ; Virginie Leroy; Hugues Gervais
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2017-08-04
Filing date: 2018-07-18
Publication date: 2019-02-07
Also published as: FR3069975B1; FR3069975A1

Abstract

The invention relates mainly to a rotating electric machine (10), in particular for a motor vehicle, characterised in that the rotor (12) includes at least one part (37) for holding the permanent magnet (29) including: - a first portion (38) arranged to exert a first holding force (F1) on a first face of the permanent magnet (29); - a second portion (40) arranged to exert a second holding force (F2) on a second face of the permanent magnet (29), the second force (F2) being perpendicular to the first holding force (F1); - a third portion (42) arranged to exert a third holding force (F3) on a third face of the permanent magnet (29), the third holding force (F3) being perpendicular to the first holding force (F1) and to the second holding force (F2).

Description

ROTOR OF ROTATING ELECTRIC MACHINE WITH PERMANENT MAGNET HOLDER FOLLOWING THREE DIMENSIONS

The present invention relates to a rotating electric machine rotor provided with a permanent magnet holding part in three dimensions.

In known manner, the rotating electrical machines comprise a stator and a rotor secured to a shaft. The rotor may be integral with a driving shaft and / or driven and may belong to a rotating electrical machine in the form of an alternator, an electric motor, or a reversible machine that can operate in both modes.

The stator is mounted in a housing configured to rotate the shaft on bearings by bearings. The stator comprises a body constituted by a stack of thin sheets forming a ring, the inner face of which is provided with notches open towards the inside to receive a coil. The winding is obtained for example from a continuous wire covered with enamel or from conductive elements in the form of pins connected together by welding. The winding comprises polyphase windings connected in star or delta whose outputs are connected to a bridge rectifier. Furthermore, the rotor may comprise a body formed by a pack of sheets made of a magnetic material, in particular steel, as well as poles formed by a plurality of permanent magnets housed in cavities of the body.

Given the manufacturing tolerances of the various parts, it is possible that the magnets are poorly plated inside the cavities. This is likely to cause deterioration of the magnets due to shocks between the magnets and the internal faces of the cavities during operation of the electric machine, or because of shocks between two magnets with each other during operation of the electric machine. As illustrated in FIG. 1, in order to compensate for the mounting clearance, it is known to insert into each cavity 2 intended to accommodate the magnets 3, a spring 4 exerting a holding force on the corresponding magnets 3. A flange 5 closing the cavities can also be used to achieve balancing of the rotor. Reference can be made to WO13175117 for more details on this device. However, it was found that during the phases of rotor speed change, there remained shocks between the magnets and the circumferential faces of the cavities likely to break the magnets or shocks between two magnets between them also likely to break the magnets.

The invention aims to effectively remedy this disadvantage by proposing a rotating electrical machine, in particular for a motor vehicle, comprising:

- a stator,

a rotor comprising:

a body comprising at least one cavity,

at least one permanent magnet disposed in the cavity, the permanent magnet comprising at least one parallelepipedal portion,

characterized in that the rotor comprises at least one permanent magnet holding part comprising:

a first part arranged to exert a first holding force on a first face of the permanent magnet,

a second part arranged to exert a second holding force on a second face of the permanent magnet, the second force being perpendicular to the first holding force,

- A third portion arranged to exert a third holding force on a third face of the permanent magnet, the third holding force being perpendicular to the first holding force and the second holding force.

The invention thus makes it possible to maintain the magnet in the three dimensions of the cavity and thus to overcome the displacements of the magnet due to the mounting clearances likely to cause its deterioration.

In one embodiment, the first portion and the third portion extend in the same axial direction, projecting from the second portion. This facilitates the mounting of the magnet in the cavity.

According to one embodiment, the first, second and third parts of the holding part are leaf springs.

According to one embodiment, a spring blade comprises at least one boss, in particular located opposite a face of the permanent magnet.

According to one embodiment each leaf spring comprises at least one boss arranged to perform the corresponding holding force.

This makes it possible to carry out the pressing force against the face of the magnet, and to guarantee a good hold despite the tolerances existing during the manufacture of each permanent magnet.

In one embodiment, the holding piece is a single piece.

According to one embodiment, the holding piece is made of a non-magnetic material, in particular stainless steel.

According to one embodiment, the retaining piece comprises a flap tab to ensure a retention of the permanent magnet in the cavity during assembly of a closure flange of the cavity.

In one embodiment, the rotor body has a plurality of permanent magnets disposed in the cavity.

In one embodiment, at least two of the three leaf springs have as many bosses as permanent magnets. This makes it possible to apply a holding force on the face of each magnet vis-à-vis the corresponding leaf spring.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given for illustrative but not limiting of the invention.

Figure 1, already described, is an exploded perspective view of a rotor provided with holding springs according to the state of the art; Figure 2 is a sectional view of the rotating electrical machine according to the present invention;

Figure 3 is a partial perspective view of the rotor showing by transparency the positioning of the holding parts according to the invention inside the magnet cavities;

Figures 4a and 4b are perspective views of a holding piece according to the present before and after respectively that the flap tab has been folded.

Identical, similar or similar elements retain the same reference from one figure to another.

FIG. 2 shows a rotating electrical machine 10 comprising a stator 1 1 surrounding a rotor 12 mounted on a shaft 13 with the presence of an air gap between the outer periphery of the rotor 12 and the inner periphery of the stator January 1. The stator January 1 is fixedly mounted inside a housing 16 rotating the shaft 13 of the rotor 12. For this purpose, the housing 16 comprises a front bearing 17 and a rear bearing 18 each provided with a housing receiving a bearing 21, in particular a ball bearing, interposed radially between the shaft 13 and the bearing of the corresponding electrical machine.

The stator January 1 comprises a body 24 constituted by a stack of thin sheets forming a ring, whose inner face is provided with notches open towards the inside to receive a coil 25. The coil 25 is obtained for example from a continuous wire covered with enamel or from conductive elements in the form of pins connected together by welding. The winding comprises polyphase windings connected in star or delta whose outputs are connected to a bridge rectifier.

Moreover, as can be seen in FIG. 3, the rotor 12 comprises a body 28 formed by a bundle of sheets made of a magnetic material, in particular steel, as well as a plurality of permanent magnets 29 intended to be housed. in the cavities 30 of the rotor body 28. The sheets of the body 28 can be held by means of rivets 33 passing axially through the rotor 12 through holes provided for this purpose. effect. Alternatively, the sheets are held together by gluing, welding, or buttoning.

The rotor body 28 has a central opening 35 for the passage of the shaft 13 extending along the axis X corresponding to the axis of the electric machine 10. The shaft 13 can be force-fitted inside opening 35 to rotate the rotor body 28 with the shaft 13.

More specifically, the cavities 30 may be axially through or blind configuration, that is to say they open on one axial side of the body. In a sectional plane P perpendicular to the axis X, the largest side of a cavity extends in a radial direction relative to the axis X. Alternatively, the cavities 30 extend in a orthoradial direction by relative to the X axis. Alternatively, two adjacent cavities form a V in the orthogonal plane P.

Each cavity 30 receives a plurality of magnets 29 stacked axially on each other. In this case, each cavity 30 receives four magnets 29 of parallelepipedal shape. Alternatively, the number of magnets 29 may of course be different. A single magnet 29 may also be inserted inside each cavity 30. The permanent magnets 29 may be made of rare earth or ferrite depending on the applications and the desired power of the electrical machine 10. The magnets 29 have a parallelepiped shape but could alternatively further include a bevelled portion at one of their ends.

As can be seen in FIG. 3, a part 37 maintains the magnets 29 inside the corresponding cavity 30. This holding piece 37 is advantageously made of a non-magnetic material, in particular stainless steel.

This holding piece 37 has a first portion 38 arranged to exert a first holding force F1 on a first face of the magnets 29. This first holding force F1 is applied in a radial direction towards an outer periphery of the rotor body 28. For this purpose, as illustrated in FIGS. 4a and 4b, the first part 38 takes the form of a spring strip provided with bosses 39 each located opposite a magnet 29. The spring strip 38 is located on the side of the inner periphery of the rotor 12 and is interposed between the magnets 29 of the cavity 30 and an inner bearing surface of the cavity 30 facing the outer periphery of the rotor body 28. Each boss 39 is compressed to the inside the cavity 30 and applies by reaction on a corresponding magnet 29 a force F1 in a radial direction relative to the axis X.

A second portion 40 is arranged to exert a second holding force F2 on a second face of an end magnet 29 of the cavity 30. The second holding force F2 is perpendicular to the first force F1.

For this purpose, the second portion 40 takes the form of a leaf spring provided with a boss 41 for the application of an axial holding force F2 on the stack of magnets 29 inside the cavity 30 corresponding.

The leaf spring 40 extends substantially perpendicular to the direction of longitudinal elongation of the leaf spring 38. The boss 41 is intended to be compressed between an end magnet 29 of the stack and a closure flange 48 for the application by reaction of the axial holding force F2. Alternatively, the leaf spring 40 has two bosses 41 or more.

A third portion 42 is arranged to exert a third holding force F3 on a third face of the magnets 29 of the cavity 30. The third holding force F3 is perpendicular to the first F1 and the second F2 holding force.

For this purpose, the third portion 42 takes the form of a leaf spring provided with bosses 43 each located vis-à-vis a magnet 29 of the cavity. The leaf spring 42 is interposed between the magnets 29 of the cavity 30 and an inner orthoradial support face of the cavity 30. Each boss 43 is compressed inside the cavity 30 and applies by reaction on a corresponding magnet 29 a F3 force in a direction orthoradiale relative to the axis X of the electric machine 10. Advantageously, the leaf springs 38, 40, 42 are formed from the transformation, stamping, stamping, or other, of the same metal piece, so that the holding piece 37 is monobloc. According to the example shown, the second spring leaf 40 is folded relative to the first leaf spring 38 so as to generally have an L shape. The third leaf spring 42 is derived from a longitudinal edge of the second leaf spring 40, as shown in FIG. that this is shown in Figures 4a and 4b.

Advantageously, the holding piece 37 has a flap tab 45 to allow the permanent magnets 29 to be held in the cavity 30 when a closing flange 48 of the cavity 30 is mounted.

Indeed, a closure flange 48 visible in FIG. 2 is placed on each axial end face of the rotor body 28 in order to close one end of the cavities 30. For this purpose, fastening members 49, such as that clamping screws are inserted inside fixing holes formed in the flanges 48 and the rotor body 28. Advantageously, the closing flanges 48 are made of a non-magnetic material having a high mechanical rigidity, for example in non-magnetic steel. These flanges 48 can further ensure a balance of the rotor 12 while allowing good retention of the magnets 29 within their cavity 30. The balancing can be performed by adding or removing material. The removal of material may be performed by machining projecting studs, while the addition of material may be performed by implanting elements in openings provided for this purpose and distributed along the circumference of the flange 48.

The method of assembly of the rotor 12 consisting first of putting the lower flange 48 in position and then of putting in place the assembly formed by the shaft 13 and the rotor body 28 is described below.

The holding pieces 37 are then inserted into the cavities 30 in such a way that the first spring leaf 38 bears against the face of the cavity 30 located on the side of the shaft 13 of the rotor 12, that the second leaf spring 40 comes in abutment against the end face of the lower flange 48, and that the third spring leaf 42 bears against an orthoradial face of the cavity 30. The magnets 29 are inserted in packets inside the cavities 30 so as to compress the bosses 39, 43 of the first and third spring strips 38, 42 to apply the holding forces F1 and F3 on the stack of magnets 29. The flap tongues 45 are then folded to hold the magnets during the fixing operation of the upper flange 48. The closing of the cavity 30 by the upper flange 48 has the effect of compressing the boss 41 of the second leaf spring 40 to apply the axial retaining force F2 on the magnets 29. The holding piece 37 thus maintains the permanent magnets 29 in the three directions (axial, radial and orthoradial), which limits their movement inside the cavity 30 and therefore the risk of breakage during the phases of abrupt change of rotor speed 12. Such a limitation of the displacement of the permanent magnets 29 inside the cavity 30 limits the impacts on the eq. balancing of the rotor during phases of abrupt change of the latter or during vibrations in the three directions mentioned above.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention which would not be overcome by replacing the different elements by any other equivalent.

In addition, the various features, variations, and / or embodiments of the present invention may be associated with each other in various combinations, to the extent that they are not incompatible or exclusive of each other.

Claims

1. Rotating electrical machine (10), in particular for a motor vehicle, comprising:

a stator (1 1),

a rotor (12) comprising:

a body (28) comprising at least one cavity (30),

at least one permanent magnet (29) disposed in the cavity (30), the permanent magnet (29) comprising at least one parallelepipedal portion,

characterized in that the rotor (12) has at least one holding piece (37) of the permanent magnet (29) comprising:

a first part (38) arranged to exert a first holding force (F1) on a first face of the permanent magnet (29),

a second part (40) arranged to exert a second holding force (F2) on a second face of the permanent magnet (29), the second force (F2) being perpendicular to the first holding force (F1),

a third part (42) arranged to exert a third holding force (F3) on a third face of the permanent magnet (29), the third holding force (F3) being perpendicular to the first holding force (F1) and at the second holding effort (F2).

2. Rotating electrical machine according to claim 1, characterized in that the first, second, and third portions (38, 40, 42) of the holding piece (37) are leaf springs.

3. Rotating electric machine according to claim 2, characterized in that a leaf spring (38, 40, 42) comprises at least one boss (39,

41, 43) in particular located opposite one side of the permanent magnet (29).

4. rotary electric machine according to any one of claims 1 to 3, characterized in that the holding piece (37) is a single piece.

5. Rotating electric machine according to any one of claims 1 to 4, characterized in that the holding piece (37) is made of a non-magnetic material, especially stainless steel.

6. rotary electric machine according to any one of claims 1 to 5, characterized in that the holding piece (37) comprises a flap tongue (45) to ensure a maintenance of the permanent magnet (29) in the cavity (30) when mounting a closure flange (48) of the cavity (30).

7. A rotary electric machine according to any one of claims 1 to 6, characterized in that the rotor body (28) comprises a plurality of permanent magnets (29) disposed in the cavity (30).

8. rotary electric machine according to claims 3 and 7, characterized in that at least two of the three leaf springs (38, 40, 42) have as many bosses as permanent magnets (29).