WO2014016100A2

WO2014016100A2 - Rotor arrangement for an electrical machine and bearing of said rotor arrangement

Info

Publication number: WO2014016100A2
Application number: PCT/EP2013/064166
Authority: WO
Inventors: Marius-Ovidiu Popescu; Michael Haider; Michael Nigro; Kurt Reutlinger
Original assignee: Robert Bosch Gmbh
Priority date: 2012-07-25
Filing date: 2013-07-04
Publication date: 2014-01-30
Also published as: WO2014016100A3; DE102012213075A1

Abstract

The invention relates to a method for mounting a sensor wheel (20) of a position sensor on a rotor arrangement, wherein the rotor arrangement has a rotor body (2, 12, 42), which is arranged on a rotor shaft (1, 11, 41) and comprises at least one rotor part (23, 123, 42) for providing an exciter magnetic field, including the following steps: arrangement of the sensor wheel (20) on the rotor body (2, 12, 42); aligning the sensor wheel (20) in relation to a position of the rotor body (2, 12, 42); and fastening the sensor wheel (20) to the rotor body (2, 12, 42) such that the sensor wheel (20) and the rotor body (2, 12, 42) bear directly against each other.

Description

description

Rotor arrangement for an electric machine

and storage of the rotor assembly

Technical area

The present invention relates to electrical machines, in particular hybrid-excited homopolar machines. Furthermore, the present invention relates to a structure of rotor assemblies of hybrid-excited Homopolarmaschinen.

State of the art

In electrically assisted vehicle steering systems, an electric motor engages the steering to increase the driver's steering effort. For this purpose, an electric machine is connected via a rigid gear to the handlebar, wherein the electric machine is controlled so that a steering movement of the driver is supported. Depending on the type of electric motor used, torque fluctuations occur which can be felt when the steering wheel is actuated.

Furthermore, depending on the type of electric motor used, in the event of a fault, a counter-torque may occur which counteracts the movement of the steering wheel and makes steering more difficult. An essential requirement of an electric motor for steering power assistance is that errors in the electric motor do not endanger the driver. Since, when using brush-commutated electric motors, high cogging torques can occur in the event of a fault, an electronically commutated electric motor is usually provided as the electric motor for a steering power assistance. In particular, Hends hybrid-excited homopolar machines used as an electric motor for use in a steering power assistance.

For an electronic commutation of an electric machine, a precise knowledge of the rotor position is required. For this purpose, rotor position sensors in the form of encoder wheels on the rotor shaft are usually provided in the interior of the electrical machine, which are aligned in a defined manner to the rotor position and have a magnetic, optical or other coding. In particular, magnetic encoder wheels are used, which have a specific structure or a specific magnetization pattern.

Disclosure of the invention

According to the invention, a method for constructing a rotor assembly for an electric machine according to claim 1 and the rotor assembly according to the independent claims are provided.

Further advantageous embodiments of the present invention are specified in the dependent claims.

According to a first aspect, a method is provided for mounting a sensor wheel of a position sensor on a rotor arrangement, wherein the rotor arrangement has a rotor body arranged on a rotor shaft, which comprises at least one rotor part for providing a field magnetic field, comprising the following steps:

- Arranging the encoder wheel on the rotor body; and

- Aligning the encoder wheel with respect to a position of at least one rotor part; and

- Attaching the encoder wheel on the rotor body, so that the encoder wheel and the rotor body abut directly against each other.

One idea of the above method for mounting a sensor wheel of a position sensor on a rotor assembly is to arrange a sensor rider wheel with respect to a rotor shaft of the rotor assembly so that it has a defined position with respect to the rotor topology. As a result, a position sensor constructed using the sensor rider wheel can reliably detect the rotor position and provide an absolute value for the rotor position. An idea is moreover to mount the sensor rider wheel not directly on the rotor shaft but directly on a rotor body mounted on the rotor shaft, so that the relative angular position of the sensor rake wheel with respect to the rotor shaft can be determined in a simpler manner.

Furthermore, for arranging the encoder wheel can be pushed onto a tapered end portion of the rotor body.

Alternatively, the encoder wheel can be applied to a front end of the rotor body for arranging.

According to one embodiment, the sender wheel may be fixed by means of an annular element which is placed on the rotor shaft, so that the sender wheel is arranged between the rotor body and the annular element, wherein the annular element

is formed soft magnetic, in order to exert a holding force against the encoder wheel in the direction of the rotor part by a magnetic field provided by one or more arranged in the rotor part permanent magnet, or

- Is magnetically designed to exert a holding force against the encoder wheel in the direction of the rotor part, which is formed soft magnetic.

Alternatively, the donor gear may be concentrically attached to an annular member, the annular member being soft magnetic and mounted on the rotor shaft so as to abut directly on the rotor member and by a magnetic field provided by a permanent magnet disposed in the rotor member , is held.

Furthermore, the encoder wheel can be fixed by gluing or welding to the rotor body.

In another aspect, there is provided a rotor assembly for an electric machine, comprising:

a rotor shaft;

- A rotor body which is placed on the rotor shaft; and a sender wheel of a position sensor, which rests directly on the rotor body and is fastened by a fastening device on the rotor body in a position oriented relative to the rotor body.

According to one embodiment, the fastening device may comprise an annular element which is placed on the rotor shaft, so that the encoder wheel between the rotor body and the annular element is arranged, wherein the annular element

Alternatively it can be placed with at least one permanent magnet on the rotor body, a rotor part.

Furthermore, the donor wheel can be mounted concentrically on an annular element, wherein the annular element is soft magnetic and is placed on the rotor shaft, so that it bears directly against the rotor part and held by a magnetic field provided by the at least one permanent magnet becomes.

Brief description of the drawings

Preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. Show it:

Figures 1 a-1 c process steps for constructing a rotor for a

electric machine until before the step of attaching a sensor Berberrads;

FIGS. 2a-2c show method steps according to a further embodiment for constructing a rotor for an electric motor; until the step of attaching the sensor wheel;

FIGS. 3a-3c show method steps according to a further embodiment for constructing a rotor for an electrical machine until prior to the step of attaching the sensor rim;

Figures 4a-4i representations of the attachment of the sensor Berber in different attachment variants; and

FIGS. 5a-5d show a method for constructing an electrical machine with the above rotor arrangement.

Description of embodiments

FIGS. 1 a to 1 c show the first method steps for constructing a rotor for a hybrid-excited homopolar machine. The rotor assembly to be constructed has two rotor parts, which are mounted at a distance from each other on a shaft to receive a stator fixedly arranged exciter coil.

In the method step shown in FIG. 1 a, a rotor core 2 is applied to a rotor shaft 1. The rotor core 2 is formed of a soft magnetic material and has a first portion 21 and a second portion 22 which are formed to receive respective rotor parts. For this purpose, the outer diameter is adapted to an inner diameter of the aufzusetzenden rotor part. Between the first and second rotor core portions 21, 22 of the rotor core 2, there is provided an enlarged-diameter center portion 23 which is designed to receive an exciting magnetic field impressed by an exciting coil (not shown).

The rotor core 2 is pressed onto the shaft 1, so that the rotor core 2 is held with a press fit on the shaft 1. For fixing one or more press notches 6 can be provided on the shaft 1. In a subsequent step shown in FIG. 1 b, a first rotor part 3, which is formed from a soft magnetic material in which permanent magnets are embedded for forming rotor poles, is pushed onto the first rotor core section 21 of the rotor core 2. For this purpose, the first rotor part 3 has an inner diameter which corresponds to an outer diameter of the first section 21 of the rotor core 2, so that a suitable fit of the first rotor part 3 on the first rotor core section 21 is achieved.

By providing the diameter of the first rotor core portion 21 of the rotor core 2 larger than that of the shaft 1, the first rotor portion 3 can be reliably held by using unused press notches on the rotor core portion 21 or by a press fit. It is thereby avoided that the first rotor part 3 is held on a portion of the shaft 1, over which the rotor core 2 or the center section 23 of the rotor core 2 has previously been slid, whereby any press notches have been damaged or made unusable.

As shown in Figure 1 c, after pushing the first rotor part 3 on the first portion 21 of the rotor core 2, a first bearing 4 are pressed onto the rotor shaft 1.

FIGS. 2a to 2c show an alternative method of constructing a rotor assembly up to the step of attaching a sensor rotor. In Figure 2a is shown that a rotor core 12 is pushed onto a rotor shaft 1 1 from a first side. The rotor core 12 has, unlike the rotor core 2 described above, only one edge portion 123 corresponding to the above-described center portion 23 and a rotor portion 121, while no rotor core portion is provided on a side of the edge portion 123 opposite to the rotor core portion 121.

After pushing the rotor core 12 onto the rotor shaft 1 1, a first rotor part 13 is pushed from a second side of the rotor shaft 1 1, as shown in Figure 2b, which has an inner diameter which corresponds approximately to the outer diameter of the rotor shaft 1 1. The first rotor part 13 is pressed onto the rotor shaft 1 1 so that it is held in a press fit and / or by press notches 6 on the rotor shaft 1 1. After postponing the first rotor part 13 on the rotor shaft 1 1, a first bearing 14 is pushed from the same side to the rotor shaft 1 1.

The application of the rotor core 12 to the rotor shaft 1 1 via a first end of the rotor shaft 1 1, which is different from the second end over which the first rotor part 13 and the first bearing 14 are applied, has the advantage that the rotor part 13 can be pressed onto the rotor shaft 1 1 "unused" press notches or "unused" sections of press notches, so that a more reliable mounting of the first rotor part 13 is achieved.

FIGS. 3a to 3c show an alternative method for constructing a rotor arrangement. FIG. 3 a shows that a rotor core 42 is pushed onto a rotor shaft 41 from a first side. The rotor core 42 has, in contrast to the rotor core 2 described above, only one of the above-described center section 23 corresponding section. The rotor core

42 has a central opening 46 for receiving on the shaft 41, wherein the central opening has one or more extensions 45, remain at least one or more press notches 47 of the rotor shaft 41 undamaged when pressing the rotor core 42.

After pushing the rotor core 42 onto the rotor shaft 41, a first rotor part 43 is pushed from a second side of the rotor shaft 1 1, as shown in Figure 3b, which has an inner diameter which corresponds approximately to the outer diameter of the rotor shaft 1 1. The first rotor part 43 is pressed onto the rotor shaft 41, so that this in an interference fit and / or by

Press notches 6 is held on the rotor shaft 41. After pushing the first rotor part 43 onto the rotor shaft 41, a first bearing 44 is pushed onto the rotor shaft 41 from the same side. The application of the rotor core 42 to the rotor shaft 41 via a first end of the rotor shaft 41, which is different from the second end, over which the first rotor part 43 and the first bearing 44 is applied, has the advantage that the rotor part 43 on the Rotor shaft 41 can be pressed over "unused" press notches or "unused" sections of press notches, so that a more reliable support of the first rotor part 43 is achieved. After the process steps for assembling the rotor arrangement shown in FIGS. 1c and 2c, a sensor rake wheel 20 is now applied on the side opposite the first rotor part 3, 13 relative to the center section 23. The sensor wheel 20 is usually designed as an annular element which serves for the optical or magnetic detection of a movement of the rotor shaft 1, 1 1. For example, the sensor wheel 20 can be designed as a structured soft-magnetic ring, a ring formed with different-pole magnetic regions, a ring with optically recognizable markings or structuring on one of its surfaces or the like. The sensor rake 20 is applied on a stepped end portion of the rotor core portion 22, 121 or disposed adjacent to an end face of the rotor core portion 22, 121.

FIGS. 4a to 4i show different types of mounting of the sensor wheel 20. In the embodiment of FIG. 4a, the sensor wheel 20 is applied to the end portion 24 of the rotor core 2, which has a smaller diameter than the rotor core portion 22, 121 in question, and adheres to it. Before bonding or during the curing phase of the adhesive, the sensor wheel 20 can be aligned with respect to the rotor shaft 1 so as to achieve a defined angular position between the rotor parts 3, 13 and the sensor wheel 20.

In FIG. 4b, the sensor wheel 20 is mounted on the sensor rim 20 on the end section of the rotor core 2 instead of by gluing using a clip connection with a recess on the end section and a corresponding latching element. The clip connection is not circumferential, so that likewise a predefined angular position of the sensor rim 20 on the end section 24 can be achieved. Of course, the sensor wheel 20 can also be clipped onto directly on the rotor shaft 1, 1 1, so as a

Spacing between the sensor wheel 20 and the rotor core 2 to achieve.

If the end section 24 is longer in the axial direction than the sensor rim 20 or if the relevant rotor core section 22, 121 projects beyond the sensor rim 20, the sensor rim 20 can be caulked on the end section 24, as shown in FIG that between a caulking point 25 and the step between the end portion 24 and the rotor core portion 22, 121 of the rotor core 2 is clamped and thus reliably held in the intended angular position.

In FIG. 4 d, the attachment of the sensor rim 20 on the end face of the rotor section is shown by means of a screw connection through a hollow screw 26, which surrounds the rotor shaft 1, 1 1 in the mounted state and engages in an internal thread in the rotor body 2. This likewise makes it possible to fix the sensor rim 20 in the same way as it does with regard to angular position.

Alternatively, as shown in Figure 4e, a fixation can be provided with a screw connection even with an attachment of the sensor wheel 20 on a tapered end portion 24 of the rotor core 2.

As shown in FIG. 4f, instead of bonding, the sensor rim 20 can also be welded to the end section 24 at a weld S, preferably at the front-side interface between the sensor rim 20 and the end section 24.

Another embodiment is shown in FIG. 4g. There, the sensor wheel 20 using an additional magnetic retaining ring 28 whose poling z. B. is aligned in the axial direction, fixed to the rotor core 2. For this purpose, the rotor core 2 is formed soft magnetic at least in the region of the end face F, so that the sensor rake 20 can be held by clamping by acting between the magnetic retaining ring 28 and the end face of the rotor core portion 22, 121 magnetic force.

Of course, as shown in Figure 4h, the sensor wheel 20 may also be held by clamping on the end portion 24 by means of the magnetic retaining ring 28. The holding of the sensor wheel 20 by means of the magnetic retaining ring 28 allows a very simple readjustment of the relative angular position of the sensor cam 20 with respect to the rotor parts of the rotor.

FIG. 4i shows a further embodiment in which the sensor rake wheel 20 is mounted on a round metal plate 29 which has a minimum diameter which is twice the distance between one and the other. gate parts provided corresponding permanent magnet. The sensor rim 20 can then be attached after application of the second rotor part to an outer end face of the second rotor part 22 by the metal plate, which carries the sensor cam 20 is magnetically held by the permanent magnets of the second rotor part 22.

FIGS. 5a to 5d further describe the method for the further construction of the hybrid-excited homopolar engine with the previously partially manufactured rotor arrangement. As shown in FIG. 5 a, the first bearing 4 are inserted into a pot-shaped housing 50 of the electrical machine into a corresponding first bearing holder 51 and then a stator arrangement 52 is inserted into the housing 50. The stator assembly 52 has stator coils 53 and a central excitation coil 54 which is oriented transversely to the axial direction of the electric machine. When the stator arrangement 52 is inserted, the exciter coil 54 comes to lie radially over the center section 23 of the rotor core 2, so that an additional excitation magnetic field can be impressed into the rotor arrangement via the excitation coil 54 during operation.

As shown in step 5b, now the second rotor part 5 is pushed onto the rotor core portion 22 of the rotor core 2 and the open end side of the pot-shaped housing 50 is closed with a corresponding housing cover 55.

The housing cover 55 has on its outer side a concavity, in which a second bearing 10, as shown in Figure 5d, is used to complete the assembly of the electric machine.

During the assembly step of FIG. 5c with previously mounted sensor rim 20 immediately after the second rotor part has been applied, in the variant in which the sensor rim 20 is mounted on a metal plate, the application of the sensor rim 20 and the metal plate to the front side can be an intermediate step be provided of the second rotor part 22 before the housing cover 55 is placed.

Claims

Expectations

1 . Method for mounting a sensor wheel (20) of a position sensor on a rotor arrangement, the rotor arrangement having a rotor body (2, 12, 42) arranged on a rotor shaft (1, 11, 41) and having at least one rotor part (23, 123, 42 ) for providing an exciter magnetic field, with the following steps:

- Arranging the sensor wheel (20) on the rotor body (2, 12, 42);

- Aligning the sensor wheel (20) with respect to a position of the rotor body (2, 12, 42); and

- Attaching the sensor wheel (20) to the rotor body (2, 12, 42) so that the sensor wheel (20) and the rotor body (2, 12, 42) lie directly against each other.

2. The method according to claim 1, wherein for arranging the sensor wheel (20) is pushed onto a tapered end section of the rotor body (2, 12, 42).

3. The method according to claim 1, wherein for arranging the sensor wheel (20) is placed on a front end of the rotor body (2, 12, 42).

4. The method according to claim 2 or 3, wherein the sensor wheel (20) is fastened using an annular element which is placed on the rotor shaft (1, 11, 41), so that the sensor wheel (20) is between the rotor body (2 , 12, 42) and the annular element (28), the annular element (28)

- is designed to be soft magnetic in order to exert a holding force against the sensor wheel (20) in the direction of the rotor part (22, 121) by a magnetic field provided by one or more permanent magnets arranged in the rotor part (22, 121), or

- Is designed magnetically to exert a holding force against the sensor wheel (20) in the direction of the rotor part (22, 121), which is designed to be soft magnetic.

Method according to claim 2 or 3, wherein the encoder wheel (20) is attached concentrically to an annular element (28), the annular element (28) being designed to be soft magnetic and being placed on the rotor shaft (1, 1 1) so that it rests directly on the rotor part (22, 121) and is held thereon by a magnetic field which is provided by a permanent magnet arranged in the rotor part (22, 121).

Method according to claim 2 or 3, wherein the sensor wheel (20) is attached to the rotor body (2, 12, 42) by gluing or welding.

Rotor arrangement for an electrical machine, comprising:

- a rotor shaft (1, 11, 41);

- a rotor body (2, 12, 42) which is placed on the rotor shaft (1, 11, 41); and

- a sensor wheel (20) of a position sensor, which rests directly on the rotor body (2, 12, 42) and is fastened to the rotor body (2, 12, 42) by a fastening device in a position aligned with the rotor body

Rotor arrangement according to claim 7, wherein the fastening device comprises an annular element (28) which is placed on the rotor shaft (1, 1 1, 41), so that the sensor wheel (20) between the rotor body (2, 12, 42) and the annular element (28) is arranged, the annular element (28)

Rotor arrangement according to one of claims 7 to 8, wherein a rotor part (22, 121) with at least one permanent magnet is placed on the rotor body (2, 12, 42).

10. Rotor arrangement according to claim 9, wherein the sensor wheel (20) is attached concentrically to an annular element (28), wherein the annular element (28) is designed to be soft magnetic and is placed on the rotor shaft (1, 1 1, 41), so that it rests directly on the rotor part (22, 121) and is held thereon by a magnetic field provided by the at least one permanent magnet.