DE102018103990A1 - Rotor unit for an electric motor - Google Patents

Abstract

The invention relates to a rotor unit for an electric motor (1) having an annular rotor core (12) surrounding a motor shaft (101) with a central axis (J) extending in the vertical direction, a plurality of permanent magnets arranged on an outer side on the rotor core (12). 13), a holder (11) holding the permanent magnets (13) and a fixing sleeve (14) surrounding the holder (11) at its outer circumference and securing the permanent magnets (13) outward in the radial direction of the shaft (J) characterized in that the holder (11) has an annular connecting portion (111) having a number of recesses (111b) at an outer portion (111c), the recesses (111b) being respectively formed by side surfaces (111d) and a bottom surface (111e) are limited, wherein the bottom surface (111 e) at an angle α relative to a radial plane of the central axis (J) is aligned and the fixing sleeve (14) in the recesses (111 b) is attached.

Description

The present invention relates to a rotor unit for an electric motor having the features of the preamble of claim 1, an electric motor equipped with such a rotor unit, and a method of manufacturing a rotor unit.

Electric motors are known from the prior art, in which a rotor shaft is rotatably mounted in a housing and the rotor shaft carries an array of permanent magnets which are non-rotatably connected to the rotor shaft. A stator surrounds the rotor unit. When the stator is energized, the rotor unit is set in rotation by the resulting electromagnetic force.

The patent US 5,563,463 shows such an electric motor, in which the permanent magnets are arranged from the outside on a magnetic carrier and then held there by a fixing sleeve so that they can not be detached from the magnetic carrier. The fixing sleeve is designed to be longer than the individual magnets in the axial direction of the arrangement. When mounted on the rotor, it projects beyond the magnets in the axial direction. The fixation sleeve is fixed after placement on the magnet assembly characterized in that it is provided at its axial ends with annular mounting discs which define the sleeve in the axial direction on the magnet assembly. In this electric motor, it is disadvantageous that the rotor unit comprises many components.

It is therefore an object of the present invention to reduce the number of components of the rotor unit.

This object is achieved by a rotor unit having the features of claim 1. It is also achieved by an electric motor with such a rotor unit and by a method for manufacturing a rotor unit.

In a rotor unit for an electric motor having an annular rotor core surrounding a motor shaft having a vertically extending central axis or rotation axis, a plurality of permanent magnets disposed on an outer side of the rotor core, a holder holding the permanent magnets, and a fixing sleeve holding the holder at its outer circumference and secures the holder in the radial direction of the axis outwards, the holder has an annular connecting portion having a number of recesses at an outer region, wherein the recesses are each bounded by side surfaces and a bottom surface, wherein the bottom surface at an angle α is aligned with respect to a radial plane of the central axis and the fixing sleeve is secured in the recesses, the rotor unit can be made particularly small and easy with less required parts. This is especially true when the fixation sleeve has areas which are impressed by plastic deformation in the recesses.

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

A permanently secure attachment results especially when the bottom surfaces pass over in each case over a radius in an outer peripheral surface of the holder. In particular, it is advantageous if the regions are formed by means of an approximately bell-shaped pressing tool. In this case, the risk of compression of the fixing sleeve is reduced in spite of an approximately in the axial direction of the axis of rotation working stroke of the pressing tool when the pressing tool has a coming into the forming with the fixing sleeve in contact inner surface which tapers away from the fixing sleeve conical and their cone angle β is aligned at about 5 to 15 ° to the axial direction.

The fixing sleeve is preferably made of a non-magnetizable metal alloy, which is easily and simply plastically deformable for attachment. Here, for example, stainless steels or light metals can be used.

The weight and the dimensions are reduced when the fixing sleeve does not project beyond the connecting portion of the holder in the direction of the central axis.

The object is also achieved by an electric motor with a rotor unit having the features described above. Such an electric motor is particularly suitable as a drive motor for electrically driven vehicles due to its smaller dimensions, fewer parts and lower weight.

1. a) Bereitstellen eines Rotorkerns mit Außenflächen, auf denen Permanentmagnete angeordent sind,
2. b) Aufsetzen eines Halters auf den Rotorkern, so dass die Permanentmagnete bezüglich einer Mittelachse des Rotorkerns in Radialrichtung nach außen gehalten werden,
3. c) Aufsetzen einer Fixierungshülse auf den Halter, so dass der Halter und die davon gehaltenen Permanentmagnete von der Hülse in Radialrichtung nach außen gesichert werden,
4. d) Fixieren der Fixierungshülse an dem Halter mittels Umformung der Fixierungshülse derart, dass Bereiche der Fixierungshülse in Ausnehmungen des Halters eingeprägt werden, ergeben sich ebenfalls die oben beschriebenen Vorteile.

Because in the method of manufacturing a rotor unit, the following steps are provided:

1. a) providing a rotor core with outer surfaces on which permanent magnets are arranged,
2. b) placing a holder on the rotor core so that the permanent magnets are held radially outward with respect to a center axis of the rotor core;
3. c) placing a fixing sleeve on the holder, so that the holder and the permanent magnets held thereby are secured by the sleeve in the radially outward direction,
4. d) Fixing the fixing sleeve to the holder by means of deformation of the fixing sleeve such that areas of the fixing sleeve are impressed into recesses of the holder, the advantages described above also result.

In particular, the deformation in step d) can take place by means of a bell-shaped, internally approximately truncated cone-shaped pressing tool. Preferably, the direction of movement of the pressing works is axially parallel to the intended axis of rotation of the rotor, that is aligned in the direction of the central axis of the rotor core.

The deformation takes place preferably along the entire circumference of the fixing sleeve in the region of the edge. The edge is thereby shortened and the excess material is preferably pressed into the lower recesses of the holder by means of projecting pressing elements with edges or convex projections arranged inside the pressing tool, the position of the pressing elements in the pressing tool corresponding to the position of the recesses. The pressing edges are preferably wedge-shaped or curved.

A further advantage is that in the described method, a burr, which can remain circumferentially outside of the fixing sleeve from the deep-drawing process, smoothed and pressed inwards.

• 1: einen Elektromotor in einem Längsschnitt;
• 2: eine Rotoreinheit in einer perspektivischen Explosionsdarstellung;
• 3: eine Rotoreinheit mit montierten Magneten und montiertem Magnethalter;
• 4: die Rotoreinheit aus 3 mit aufgesetzter Fixierungshülse;
• 5: die Rotoreinheit aus 4 nach dem Befestigen der Fixierungshülse;
• 6: einen Befestigungsbereich der Rotoreinheit aus 5 in einer detaillierten Schnittdarstellung mit einem angesetzten Presswerkzeug; sowie
• 7: den Bereich aus 6 nach dem Umformvorgang.

An embodiment of the present invention will be described in more detail with reference to the drawing. Show it:

• 1 an electric motor in a longitudinal section;
• 2 a rotor unit in an exploded perspective view;
• 3 a rotor unit with mounted magnets and mounted magnet holder;
• 4 : the rotor unit off 3 with attached fixation sleeve;
• 5 : the rotor unit off 4 after fixing the fixing sleeve;
• 6 : a fixing area of the rotor unit 5 in a detailed sectional view with an attached pressing tool; such as
• 7 : the area off 6 after the forming process.

As in 1 shown, includes the electric motor 1 a motor shaft 101 in rolling bearings 105 and 106 around a rotation axis J is rotatably mounted. The rolling bearing 105 is in a housing 103 attached. The rolling bearing 106 is in a housing cover 104 attached. The housing cover 104 closes the housing 103 , Inside the case 103 is a stator 102 of the electric motor 1 attached. The stator 102 surrounds a rotor unit 10 , the rotation with the motor shaft 101 connected is. The stator 102 carries an insulator 107 on which is the winding 108 located.

Instead of the ball bearings used in the 1 for the rolling bearings 105 and 106 These bearings can also be used in a different design. They can be designed for example as plain bearings or fluid bearings.

The 2 shows the rotor unit 10 out 1 in a perspective exploded view.

A rotor core 12 the rotor unit has a bore on its inside 122 on, with the rotor core 12 can be placed on a motor shaft. The holes 121 run parallel to the axis of the bore 122 and serve for cooling and weight saving. On the outside, more precisely on the outer circumference of the rotor core 12 are attachment surfaces 123 formed substantially flat and parallel to the longitudinal axis of the bore 122 run. An even number of permanent magnets 13 , in this embodiment a total of eight, are for the rotor unit 10 intended. The permanent magnets 13 each have a shape that can be described as a section of a cylinder. A radially outwardly facing surface is curved in a plane such that this outer surface is on the outer circumference of the rotor unit 10 is rounded. In the axial direction, the surface is not curved. An opposite surface is flat. This flat surface of the permanent magnet 13 is designed to fit on the mounting surface 123 of the rotor core 12 fits. Every single permanent magnet 13 can therefore on a corresponding surface 123 of the rotor core 12 be put on.

A holder 11 includes a connecting section 111 and holding elements 112 , The connecting section 111 is annular, with an inner peripheral surface 111 and an outdoor area 111c the connecting section 111 form. In the outdoor area 111c are a total of four recesses 111b provided in to the outer surface of the holder 11 are impressed. The holding elements 112 are rod-shaped and with one end to the connecting portion 111 attached. The holding elements 112 protrude parallel to each other in the axial direction of the connecting portion 111 path. They are in the circumferential direction of the connecting portion 111 equally distributed. Overall, an even number of holding elements, in this embodiment, eight holding elements 112 . intended. Finally, a fixation sleeve 14 provided, which is cylindrical and has a diameter which allows the fixation 14 on the other components 11 . 12 and 13 sit up. The fixation sleeve 14 is slightly longer in the axial direction than the permanent magnets 13 ,

The 3 shows the rotor core 12 , the permanent magnets 13 and the holder 11 out 2 in assembled state in a perspective view. The rotor core 12 is at its here no longer visible mounting surfaces, each with a permanent magnet 13 Provided. The holder 11 is on the rotor core 12 and the permanent magnets 13 put on, in such a way that the holding elements 112 each radially outside cover a gap between the permanent magnets 13 when putting on the rotor core 12 remains. The holding elements 112 not only cover the space between the permanent magnets 13 , but also engage in the edge region of the permanent magnets 13 laterally over the permanent magnets 13 so that the permanent magnets 13 through the retaining elements 112 at the rotor core 12 being held. The recesses 111b are from the top of the connection section 111 formed here. They each have two side surfaces 111d on that the recess 111b limit in the circumferential direction, as well as a floor area 111e that the recess 111 limited downwards in the axial direction.

The arrangement off 3 is in 4 with attached fixation sleeve 14 shown in perspective. Here is the view opposite 3 changed so that the in 3 invisible bottom in the arrangement here facing the viewer. The rotor core 12 is in 4 visible. The permanent magnets 13 and the holder 11 but are of the fixing sleeve 14 covered. The fixation sleeve 14 has an outer jacket 141 on, which is tubular cylindrical. At the in 4 visible edge is an inwardly facing annular area 142 molded, whose inner edge 142a the permanent magnets covered, but not in the area of the holes 121 reached. The holes 121 stay free.

The 5 shows the arrangement 4 in another view, according to the view 3 , The fixation sleeve 14 is on the edge 141 that's the edge 142a out 4 is opposite, to a lesser extent radially inwardly formed than in the opposite side. The edge 141 covers the connection area 111 of the owner 11 in the radial direction about as far as the recesses 111b to reach. Exactly at the position where the recesses 111b under the edge 141 lie, is the fixation sleeve 14 deformed by a forming process so that deformed areas 141b arise. The areas 141b protrude into the recesses 111b into it. The fixation sleeve 14 is this way on the rotor core 12 attached and firmly encloses the holder 11 and the permanent magnets 13 , In particular, the fixation sleeve 14 attached in the axial direction, that at the in 4 visible bottom of the edge 142 the rotor core 12 and the holder 11 as well as the permanent magnets 13 covered radially inwards. In the other axial direction is the fixing sleeve 14 through the opposite edge area 141 and especially through the areas 141b fixed. In the circumferential direction of the arrangement is the fixing sleeve 14 through the areas 141b that are in the corresponding recesses 111b are formed into it, also fixed. The fixation sleeve 14 So is positively fixed both in the axial direction and in the circumferential direction of the rotor assembly. This allows the fixation sleeve 14 also their task, the permanent magnets 13 secure in the rotor assembly, run reliably.

The fixation sleeve 14 For example, it is made of a non-magnetizable metal such as aluminum. This material does not hinder the magnetic forces that drive the electric motor 1 are required and between the stator 102 and the rotor 10 Act. On the other hand, aluminum is easily permanently plastically deformable, so that for fixing the fixing sleeve 14 At the rotor assembly required deformation of the areas 141b easy to carry out.

The transformation of the areas 141b takes place in a particularly advantageous manner so that the material of the fixing sleeve 14 in the area of the recesses 111b mainly in the recesses 111b is pressed.

The longitudinal section of the recesses 111b is in the 6 shown in more detail. The recess 111b is in the circumferential direction through the visible side surface here 111d and in the axial direction through the bottom surface 111e limited. The floor area 111e goes on its outside in a radius 111f in the outer peripheral surface of the connecting portion 111 about. The radius 111f is chosen so that the transition is substantially tangential. The floor area 111e is at an angle α to the top of the outside area 111c inclined. The angle α is preferably between 15 ° and 60 °. In the illustrated embodiment, the angle is about 45 °.

The coat 141 runs in the upper illustration of the 6 outside parallel to the connecting portion 111 and surpasses this in the axial direction not or only slightly. A bell-shaped pressing tool 200 is in the 6 indicated above. The pressing tool 200 serves to deform the jacket 141 in the fields of 141 and 141b , This is the pressing tool 200 in the with the arrow F indicated movement direction movable and drivable.

For the positive fixed connection of the fixing sleeve 14 with the holder 11 becomes the upper edge area of the mantle 141 with the pressing tool 200 Tapered along the entire circumference. pressing elements 201 , For example, wedge-shaped or convex, are inside of the pressing tool 200 arranged and with the positions of the recesses 111b aligned accordingly. By the pressing elements 201 The material of the fixing sleeve is in the direction of the bottom surface 111e of the connection area 111 pressed and thereby further plastically transformed. The coat 141 then settles in this area to the radius 111f and in the recess 111b on.

While the cone angle β of the pressing tool 200 at the inner peripheral surface is about 5 ° to 15 °, the angle α is significantly larger. By the axial delivery of the pressing tool 200 becomes the edge 14a the fixing sleeve inwards on the axle J too crowded. The material of the fixing sleeve is compressed in the circumferential direction. Without additional precautions, there is a risk that the excess material will form non-reproducible irregularities in the edge area. The described construction of the pressing tool 200 makes it possible to formulate the excess material targeted into the recesses of the holder and thereby not only to achieve defined conditions, but at the same time to achieve a rotationally fixed attachment of the sleeve in the circumferential direction.

The result is a deformation of the shell 141 as they are in the 7 is visible. The area 141b is angled approximately at an angle to the mantle 141 that is with the angle α approximately 90 ° added. An advantage of this connection technology is that on the one hand, the sleeve 14 in the axial direction not or only slightly over the surface of the connecting portion 111 must stand out. This saves material. Next, it is beneficial to the floor area 111e at an angle like in 6 is aligned. The floor area 111e In particular, it does not run parallel to the radial plane that matches the outer surface of the exterior 111c coincides and perpendicular to the axis of rotation J is oriented. This angled orientation of the bottom surface 111e and in particular the low cone angle β allow it in the deformation of the shell 141 the pressing tool 200 so to lead, that in the deformation on the coat 141 acting forces remain low in the axial direction. The coat 141 is thus not deformed with appropriate dimensioning in the axial direction. The low axial forces make it possible for the jacket 141 particularly thin-walled and thus easy and material-saving form.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5563463 [0003]

Claims (15)

A rotor unit for an electric motor (1) having an annular rotor core (12) surrounding a motor shaft (101) having a center axis (J) extending in the vertical direction, a plurality of permanent magnets (13) disposed on an outer side of the rotor core (12) the holder (11) holding permanent magnets (13) and a fixing sleeve (14) surrounding the holder (11) at its outer circumference and securing the permanent magnets (13) outwards in the radial direction of the axis (J), characterized in that Holder (11) having an annular connecting portion (111) having at an outer region (111c) a number of recesses (111b), wherein the recesses (111b) respectively of side surfaces (111d) and a bottom surface (111e) are limited the bottom surface (111e) is oriented at an angle α with respect to a radial plane of the central axis (J), and the fixing sleeve (14) is secured in the recesses (111b). Rotor unit after Claim 1 , characterized in that the fixing sleeve (14) has regions (141b) which are impressed into the recesses (111b) by means of plastic deformation. Rotor unit according to one of the preceding claims, characterized in that the angle α is 15 ° to 60 °. Rotor unit according to one of the preceding claims, characterized in that the bottom surfaces (111e) pass over in each case over a radius (111f) in an outer peripheral surface of the holder (11). Rotor unit according to one of the preceding claims, characterized in that the regions (141b) are formed by means of a pressing tool (200). Rotor unit after Claim 5 , characterized in that the pressing tool (200) is movable in a direction of movement which is aligned parallel to the central axis (J). Rotor unit according to one of the preceding claims, characterized in that the fixing sleeve (14) is made of a non-magnetizable metal alloy. Rotor unit according to one of the preceding claims, characterized in that the fixing sleeve (14) does not project beyond the connecting portion (111) of the holder (11) in the direction of the central axis (J). Electric motor with a rotor unit according to one of the preceding claims. A method for producing a rotor unit, characterized in that the following steps are provided: a) providing a rotor core with outer surfaces, on which permanent magnets are angeordent, b) placing a holder on the rotor core, so that the permanent magnets with respect to a central axis (J) of the rotor core c) placing a fixing sleeve on the holder, so that the holder and the permanent magnets held thereby are secured radially outward by the sleeve, d) fixing the fixing sleeve to the holder by means of deformation of the fixing sleeve such that Regions of the fixing sleeve are impressed in recesses of the holder. Method according to Claim 10 , characterized in that the deformation by means of a pressing tool (200). Method according to Claim 11 , characterized in that the direction of movement of the pressing tool (200) is aligned parallel to the central axis (J) of the rotor core. Method according to one of the preceding Claims 10 to 12 , characterized in that the deformation takes place along the entire circumference of the fixing sleeve in the region of the edge. Method according to Claim 13 , characterized in that the edge is pressed in places by means of pressing elements (201) arranged internally on the pressing tool (200) into the recesses of the holder. Method according to Claim 14 , characterized in that the pressing elements (201) are wedge-shaped or curved.

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