CN209913592U

CN209913592U - Rotor unit for an electric motor and electric motor

Info

Publication number: CN209913592U
Application number: CN201920223605.5U
Authority: CN
Inventors: J·施密德
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2018-02-22
Filing date: 2019-02-22
Publication date: 2020-01-07
Anticipated expiration: 2029-02-22
Also published as: DE202018006076U1; DE102018103990A1

Abstract

The utility model relates to a rotor unit and motor for motor, this rotor unit has around the annular rotor core (12) of motor shaft (101) that has along the central axis (J) of vertical extension, settle a plurality of permanent magnets (13) on the surface of rotor core (12), keep this permanent magnet (13) holding device (11) and surround retaining device (11) and fix this permanent magnet (13) outwards in the footpath of axis (J) at its periphery, characterized in that the holding device (11) has an annular connecting part (111) with a plurality of notches (111b) in an outer section (111c), each notch (111b) being delimited by a plurality of side faces (111d) and a base face (111e), the bottom surface (111e) is oriented at an angle alpha relative to a radial plane of the central axis (J), and the fixing sleeve (14) is fixed in the notch (111 b).

Description

Rotor unit for an electric motor and electric motor

Technical Field

The present invention relates to a rotor unit for an electric motor, an electric motor equipped with such a rotor unit and a method of manufacturing a rotor unit.

Background

Electric motors are known from the prior art in which a rotor shaft is rotatably mounted in a housing and the rotor shaft is fitted with permanent magnet assemblies which are coupled to the rotor shaft in a rotationally fixed manner. The stator surrounds the rotor unit. When the stator is energized, the electromagnetic forces that occur rotate the rotor unit.

Patent US5,563,463 shows an electric motor in which permanent magnets are placed on a magnet holder from the outside and are then held firmly there by a retaining sleeve, so that they do not detach from the magnet holder. The fixing sleeve is here designed to be longer in the axial direction of the assembly than the individual magnets. When it is slipped onto the rotor, the retaining sleeve axially passes over the magnet. The fixing sleeve is fixed after the sleeve is placed on the magnet assembly, so that it is provided with annular fixing pieces at both axial ends thereof, which fix the sleeve on the magnet assembly in the axial direction. In the case of the electric motor, it is disadvantageous that the rotor unit comprises a plurality of components.

SUMMERY OF THE UTILITY MODEL

The object of the invention is therefore to reduce the number of components of the rotor unit.

This task is accomplished by a rotor unit. The object is also achieved by an electric motor having such a rotor unit and a method for producing a rotor unit.

In a rotor unit for an electric motor with an annular rotor core surrounding a motor shaft with a central axis extending in the vertical direction, a plurality of permanent magnets arranged on the outer surface of the rotor core, a holding device holding the permanent magnets and a fixing sleeve surrounding the holding device at its outer periphery and fixing the permanent magnets outwards in the radial direction of the axis, the holding device having an annular connecting portion with a plurality of indentations at the outer section, wherein each indentation is delimited by a plurality of side faces and a bottom face, wherein the bottom face is oriented at an angle α with respect to the radial plane of the central axis and the fixing sleeve is fixed in the indentation, the rotor unit can be constructed very small and easily with fewer required components. This is particularly suitable when the fastening sleeve has a section which is pressed into the recess by means of plastic deformation.

The angle α is preferably 15 ° to 60 °, in particular between 40 ° and 50 °.

In particular, a permanent and reliable fastening is obtained when the base surface transitions into the outer circumferential surface of the holding device by means of a radius. It is particularly advantageous if the section is deformed by means of a substantially bell-shaped pressing tool. The stamping tool is movable in a direction of motion oriented parallel to the central axis. At this time, when the press tool has an inner surface which, upon deformation, contacts the retaining sleeve and tapers away from the retaining sleeve, the taper angle β of which is oriented at about 5 ° to 15 ° relative to the axial direction, the risk of retaining sleeve upsetting is reduced despite the working stroke of the press tool in the axial direction of the axis of rotation.

The fixing sleeve is preferably made of a non-magnetizable metal alloy which is lightweight, easy to manufacture and plastically deformable. Stainless steel or light metals can be used here, for example.

The fixing sleeve does not exceed the connecting portion of the holding device in the direction of the central axis.

The weight and size are reduced when the fixing socket does not exceed the connection of the holding means in the direction of the central axis.

This object is also achieved by an electric motor having a rotor unit having the above-mentioned features. Such a motor is particularly suitable as a drive motor for an electric vehicle because of its small size, few parts, and light weight.

The invention relates to a rotor unit for an electric motor, having an annular rotor core surrounding a motor shaft having a central axis extending in the vertical direction, a plurality of permanent magnets arranged on the outer surface of the rotor core, a holding device for holding the permanent magnets, and a fixing sleeve which surrounds the holding device at its outer circumference and fixes the permanent magnets radially outward of the axis, characterized in that the holding device has an annular connection with a plurality of indentations on the outer section, wherein each of the indentations is delimited by a plurality of sides and a bottom surface, wherein the bottom surface is oriented at an angle α with respect to a radial plane of the central axis and the fixing sleeve is fixed in the indentation, the fixing sleeve has a plurality of sections which are pressed into the indentations by means of plastic deformation, the sections being deformed by means of a punching tool, the stamping tool is movable in a direction of motion oriented parallel to the central axis. The fixing sleeve is made of a non-magnetizable metal alloy. The fixing sleeve does not exceed the connecting portion of the holding device in the direction of the central axis.

The above-mentioned advantages are also obtained because the following steps are specified in the rotor unit manufacturing method:

a) providing a rotor core having an outer surface, disposing a plurality of permanent magnets on the outer surface,

b) placing the holding device onto the rotor core such that the permanent magnets are held radially outward with respect to a center axis of the rotor core,

c) placing the fixing sleeve onto the holding device, so that the holding device and the permanent magnets held thereby are fixed radially outwards by the sleeve,

d) the fixing sleeve is fixed to the holding device by deformation of the fixing sleeve, so that a section of the fixing sleeve is pressed into a recess of the holding device.

In particular, the deformation in step d) can be carried out by means of a bell-shaped stamping tool, the interior of which is substantially frustoconical. Preferably, the direction of movement of the punching tool is now oriented parallel to the axis of the predetermined axis of rotation of the rotor, i.e. in the direction of the central axis of the rotor core.

The deformation is preferably carried out in the edge region along the entire circumference of the fixing sleeve. The edge is thereby shortened and excess material is pressed into the deeper indentation of the holding device, preferably by means of a protruding stamp which is arranged in the stamping tool and has an edge or a convex projection, wherein the position of the stamp in the stamping tool corresponds to the position of the indentation. The stamped edge is preferably wedge-shaped or ridged.

It is also advantageous if, in the method, the burr that can be left on the fixing sleeve around the outside from the deep-drawing process is smoothed and pressed inward.

Drawings

An embodiment of the invention is described in detail with reference to the accompanying drawings, in which:

fig. 1 shows an electric motor in longitudinal section;

fig. 2 shows the rotor unit in an exploded perspective view;

figure 3 shows the rotor unit with the mounted magnets and magnet holder;

figure 4 shows the rotor unit of figure 3 together with a nested stationary sleeve;

fig. 5 shows the rotor unit of fig. 4 after the fixing sleeve is fixed;

fig. 6 shows a fixing section of the rotor unit of fig. 5 together with a mounted punching tool in a detailed sectional view; and

fig. 7 shows the section of fig. 6 after deformation.

Detailed Description

As shown in fig. 1, the electric motor 1 comprises a motor shaft 101 which is mounted rotatably about a rotational axis J in

rolling bearings

105, 106. The rolling bearing 105 is fixed in the housing 103. The rolling bearing 106 is fixed in the housing cover 104. The cover 104 closes the housing 103. A stator 102 of the motor 1 is fixed in the housing 103. The stator 102 surrounds the rotor unit 10 which is coupled to the motor shaft 101 in a rotationally fixed manner. Stator 102 is provided with an insulator 107 on which windings 108 are located.

Instead of the ball bearings selected for the

rolling bearings

105, 106 in fig. 1, the bearings can also be used in other configurations. They can be designed, for example, as sliding bearings or fluid bearings.

Fig. 2 illustrates the rotor unit 10 of fig. 1 in an exploded perspective view.

The rotor core 12 of the rotor unit has a bore 122 on its inner side, by means of which the rotor core 12 can be fitted to a motor shaft. A plurality of holes 121 extend parallel to the axis of the holes 122 and are used for cooling and weight reduction. On the outer side of the rotor core 12, more precisely on its outer circumference, a plurality of fixing surfaces 123 are formed, which are substantially flat and extend parallel to the longitudinal axis of the bore 122. An even number of permanent magnets 13, in this embodiment a total of eight permanent magnets, are provided for the rotor unit 10. Each permanent magnet 13 has a shape that can be described as a cylindrical section. The radially outward surface is curved in one plane so that the outer surface on the outer periphery of the rotor unit 10 is rounded. In the axial direction, the face is not curved. One opposing face is flat. The plane of the permanent magnet 13 is designed such that it matches the fastening surface 123 of the rotor core 12. Each individual permanent magnet 13 may thus be nested onto one corresponding face 123 of the rotor core 12.

The holding device 11 includes one connecting portion 111 and a plurality of holding members 112. The connection 111 is designed in the form of a ring, wherein the inner circumferential surface 111a and the outer section 111c form the connection 111. In the outer section 111c, four recesses 111b are provided, which are pressed into the outer surface of the holding device 11. The holder 112 is designed in the form of a rod and is fixed at one end to the connecting part 111. These holding pieces 112 project from the connecting portion 111 in the axial direction in parallel with each other. They are uniformly distributed in the circumferential direction of the connecting portion 111. A total of an even number of holders are provided, eight holders 112 in this embodiment. Finally, a fixing sleeve 14 is provided, which is cylindrical in design and has a diameter that allows the fixing element 14 to be slipped onto the

other component

11, 12, 13. The fixing sleeve 14 is designed to be slightly longer than the permanent magnet 13 in the axial direction.

Fig. 3 shows the rotor core 12, the permanent magnets 13 and the holding device 11 of fig. 2 in an assembled state in a perspective view. The rotor core 12 is provided with a permanent magnet 13 on its respective fastening surface, which is no longer visible here. The holding device 11 is placed over the rotor core 12 and the permanent magnets 13, specifically in such a way that the holding elements 112 cover a gap between the permanent magnets 13 when placed over the rotor core 12, respectively, at the radial outside. The holder 112 now covers not only the gap between the permanent magnets 13, but also laterally overlaps the permanent magnets 13 in the edge region of the permanent magnets 13, so that the permanent magnets 13 are held on the rotor core 12 by the holder 112. The notch 111b is formed from the top side of the connection portion 111. The recesses each have two side faces 111d, which delimit the recess 111b in the circumferential direction, and a base face 111e, which delimits the recess 111b in the axial direction downwards.

The assembly of fig. 3 is shown in perspective in fig. 4 together with the nested holster 14. The viewing angle is now changed relative to fig. 3, so that the bottom side of the component, which is not visible in fig. 3, is facing the viewer. The rotor core 12 can be seen in fig. 4. But the permanent magnet 13 and the holding means 11 are shielded by the fixing sleeve 14. The fixing sleeve 14 has a housing 141, which is designed in the form of a tubular cylinder. At the edge visible in fig. 4, an inwardly directed annular section 142 is moulded, the inner edge 142a of which covers the permanent magnet but does not reach all the way to the area of the hole 121. The aperture 121 thus remains open.

Fig. 5 shows the assembly of fig. 4 from another perspective corresponding to that of fig. 3. The fixing sleeve 14 is deformed radially inward at an edge 141a opposite to the edge 142a of fig. 4 to a smaller extent than at the opposite side. The edge 141a covers the connecting portion 111 of the holding device 11 in the radial direction approximately to the extent of reaching the notch 111 b. The fixing sleeve 14 is deformed by the deformation process at a position just below the edge 141a of the notch 111b, so that a deformed section 141b is present. The section 141b now projects into the recess 111 b. In this way, the fixing sleeve 14 is fixed on the rotor core 12 and firmly encloses the retaining means 11 and the permanent magnets 13. In particular, the fixing sleeve 14 is fixed in the axial direction in such a way that, on its bottom surface visible in fig. 4, the edge 142a covers the rotor core 12 and the holding device 11 and the permanent magnets 13 radially inward. In the other axial direction, the fixing sleeve 14 is fixed by the opposite edge regions 141a and in particular by the sections 141 b. In the circumferential direction of the assembly, the fixing sleeve 14 is also fixed by the section 141b deformed into the corresponding notch 111 b. The fixing sleeve 14 is thus positively fixed not only in the axial direction of the rotor assembly, but also in its circumferential direction. The fixing sleeve 14 thus also reliably performs its task of fixing the permanent magnets 13 in the rotor assembly.

The fixing sleeve 14 is made of, for example, a non-magnetizable metal such as aluminum. The material does not hinder the magnetic force required to drive the motor 1 and acting between the stator 102 and the rotor 10. On the other hand, aluminum is susceptible to permanent plastic deformation, and therefore, the deformation of the section 141b required to fix the fixing sleeve 14 to the rotor assembly can be easily performed.

The deformation of the section 141b is advantageously carried out in such a way that the material of the fixing sleeve 14 is pressed mainly into the recess 111b in the region of the recess 111 b.

Fig. 6 shows a longitudinal section of the notch 111b in detail. The recess 111b is delimited in the circumferential direction by the side surface 111d visible here and in the axial direction by the base surface 111 e. The bottom surface 111e transitions on its outside with a radius 111f to the outer circumferential surface of the connecting portion 111. The radius 111f is selected such that the transition extends substantially tangentially. The bottom surface 111e is inclined at an angle a relative to the top surface of the outer section 111 c. The angle α is preferably between 15 ° and 60 °. In the illustrated embodiment, the angle is about 45 °.

The housing 141 extends parallel to the connection 111 on the outside in the top view of fig. 6 and does not extend beyond it or only slightly extends beyond it in the axial direction. The bell-shaped press tool 200 is shown at the upper side in fig. 6. The press tool 200 is used for deforming the housing 141 in the

sections

141a, 141 b. For this purpose, the punching tool 200 is movable and drivable in a direction of movement indicated by the arrow F.

In order to positively fix the fixing sleeve 14 to the holding device 11, the upper edge region of the housing 141 is tapered along the entire circumference by means of the punching tool 200. A stamping 201, which is designed, for example, in the form of a wedge or a convexity, is provided on the inside on the stamping tool 200 and is aligned in a direction corresponding to the position of the indentation 111 b. By means of the stamping 201, the material of the fixing sleeve is pressed against the bottom surface 111e of the connecting part 111 and is thereby further plastically deformed. The housing 141 then abuts the radius 111f in this region and enters the recess 111 b.

In the case where the taper angle β of the press tool 200 on its inner peripheral surface is about 5 ° to 15 °, the angle α is significantly large. By axial feed of the punching tool 200, the edge 14a of the fixing sleeve is pressed inwards towards the axis J. The material of the fixing sleeve is now upset in the circumferential direction. Without additional precautions, there is the risk that the material which becomes superfluous does not form a reproducible irregularity in the edge region. The described design of the punching tool 200 allows the excess material to be purposefully deformed into the recess of the holding device and thus not only achieves the defined conditions, but at the same time also achieves a rotationally fixed fixing of the sleeve in the circumferential direction.

As a result, a deformation of the housing 141 occurs as can be seen in fig. 7. The section 141b is bent substantially at an angle to the housing 141, which angle is approximately 90 ° complementary to the angle α. In this connection technique, it is advantageous if, on the one hand, the sleeve 14 does not have to extend beyond the surface of the connecting part 111 in the axial direction or only slightly. Thereby saving material. It is also advantageous that the bottom surface 111e is oriented at an angle as shown in fig. 6. In particular, the base surface 111e does not extend parallel to a radial plane which coincides with the outer surface of the outer portion 111c and is oriented perpendicularly to the axis of rotation J. The bending orientation of the base surface 111e and in particular the small taper angle β allow the pressing tool 200 to be guided when the housing 141 is deformed, so that the forces acting on the housing 141 when deformed remain small in the axial direction. The housing 141 is thus not deformed in the axial direction with corresponding dimensioning. The small axial force allows the housing 141 to be formed with very thin walls and thus easily and material efficiently.

Claims

1. A rotor unit for an electric motor, having an annular rotor core (12) surrounding a motor shaft (101) having a central axis (J) extending in a vertical direction, a plurality of permanent magnets (13) disposed on an outer surface of the rotor core (12), a holding device (11) holding the permanent magnets (13), and a fixing sleeve (14) surrounding the holding device (11) at its outer periphery and fixing the permanent magnets (13) outward in a radial direction of the axis (J), characterized in that the holding device (11) has an annular connecting part (111) with a plurality of notches (111b) on an outer section (111c), wherein each of said indentations (111b) is delimited by a plurality of lateral surfaces (111d) and a bottom surface (111e), wherein the bottom face (111e) is oriented at an angle a with respect to a radial plane of the central axis (J) and the harness (14) is fixed in the notch (111 b).

2. Rotor unit according to claim 1, characterised in that said cover (14) has a plurality of sections (141b) pressed into said notches (111b) by plastic deformation.

3. A rotor unit according to claim 1, characterised in that the angle α is 15 ° to 60 °.

4. Rotor unit according to claim 1, characterised in that the base surfaces (111e) each transition to the outer circumferential surface of the holding device (11) by means of a radius (111 f).

5. Rotor unit according to claim 2, characterised in that the section (141b) is deformed by means of a pressing tool (200).

6. Rotor unit according to claim 5, characterised in that the punching tool (200) is movable in a direction of movement oriented parallel to the centre axis (J).

7. Rotor unit according to claim 1, characterised in that said fixing sleeve (14) is made of a non-magnetisable metal alloy.

8. A rotor unit as claimed in claim 1, characterised in that said cover (14) does not exceed said connection portion (111) of said retaining means (11) in the direction of said central axis (J).

9. An electric motor, characterized in that it has a rotor unit according to any one of claims 1-8.

10. Rotor unit for an electric motor, having an annular rotor core (12) surrounding a motor shaft (101) having a central axis (J) extending in the vertical direction, a plurality of permanent magnets (13) arranged on the outer surface of the rotor core (12), a holding device (11) holding the permanent magnets (13), and a fixing sleeve (14) surrounding the holding device (11) at its outer circumference and fixing the permanent magnets (13) radially outward of the axis (J), characterized in that the holding device (11) has an annular connecting portion (111) having a plurality of indentations (111b) on an outer section (111c), wherein each of the indentations (111b) is delimited by a plurality of side faces (111d) and one bottom face (111e), wherein the bottom face (111e) is oriented at an angle α with respect to a radial plane of the central axis (J) and the fixing sleeve (14) is fixed in the indentation (111b), the fastening sleeve (14) has a plurality of segments (141b) which are pressed into the recesses (111b) by means of plastic deformation, the segments (141b) being deformed by means of a punching tool (200), the punching tool (200) being movable in a direction of movement which is oriented parallel to the central axis (J).

11. Rotor unit according to claim 10, characterised in that said fixing sleeve (14) is made of a non-magnetisable metal alloy.

12. A rotor unit as claimed in claim 10, characterised in that said cover (14) does not exceed said connection portion (111) of said retaining means (11) in the direction of said central axis (J).

13. An electric motor having a rotor unit according to any one of claims 10 to 12.