WO2017153061A1

WO2017153061A1 - Electric machine having high rotational-speed resistance

Info

Publication number: WO2017153061A1
Application number: PCT/EP2017/050147
Authority: WO
Inventors: Armin Ploeger; Taoufiq HANNACH; Stefan Schuerg; Ivo Grahlmann; Anton Braeunig; Murat KOL
Original assignee: Robert Bosch Gmbh
Priority date: 2016-03-08
Filing date: 2017-01-04
Publication date: 2017-09-14
Also published as: DE102016203721A1

Abstract

The invention relates to a rotor (14) for an electric machine, wherein the rotor (14) has high rotational-speed resistance. The rotor (14) has at least one laminated core (16) having metal sheet laminations stacked one over the other in the direction of longitudinal extent of the rotor (14), wherein a plurality of magnet-holding channels (20) is provided near an outer circumference of the laminated core (16), which magnet-holding channels extend in the longitudinal direction of the rotor (14) and are spaced apart from each other in the circumferential direction (25) of the rotor (14) and in each of which magnet-holding channels at least one magnet element (22) is arranged. The rotor (14) is characterized in that two adjacent magnet-holding channels (20) are connected to each other by means of a connecting channel (40) in such a way that an outer region (30) of the laminated core (16) has, on the side of said outer region directed radially inward, a protruding bulge (42) bounded by the connecting channel (40), which bulge has a smaller width in the circumferential direction (25) in a region (44) radially further outside than in a region (46) radially further inside. Because of the special geometric design of the connecting channel (40), plastic material accommodated in the connecting channel (40) is loaded mainly in compression instead of in tension and therefore can withstand higher loads, the outer region (30) therefore being retained in the inner region (32) of the laminated core (16) in the manner of a tension anchor.

Description

description

title

Electric machine with high speed stability

Field of the invention

The present invention relates to an electrical machine, in particular a permanent magnet synchronous machine, and a method for producing such an electric machine.

Background of the invention

Electric machines are used for example as motors and / or generators for a variety of purposes. For example, high-performance electric machines are increasingly used in electric or hybrid vehicles in order to be able to set the motor vehicle in motion as part of a drive train and / or kinetic energy when the vehicle is decelerated

to recuperate. Particularly in such applications, the highest possible efficiency of the electric machine is always sought and at the same time attempts to achieve the highest possible power density with the smallest possible dimensions and weight of the electric machine. For this purpose, the electric machine should be able to be operated at high speeds.

In the subsequently published DE 102015203018 AI an electric machine is described in which magnets are fixed by means of an injected plastic in channels, which are provided in a rotor of the electric machine.

Disclosure of the invention

Advantages of the invention Embodiments of the present invention can advantageously make possible an electric machine which on the one hand can be robust, inexpensive to manufacture and powerful and which, on the other hand, can have a very high speed stability.

According to a first aspect of the present invention, a rotor for an electric machine is described which has a stator and the rotor rotatably mounted relative to the stator. The rotor has at least one

Disc pack with laminations stacked one above the other in the longitudinal direction of the rotor. Near an outer periphery of the disk pack is a

A plurality of extending in the longitudinal direction of the rotor and in

Circumferential direction of the rotor spaced apart

Magnet receiving channels provided, in which in each case at least one

Magnetic element is arranged. The electrical machine is characterized in that two adjacent magnet receiving channels via a

Connection channel are connected to each other such that an outer region of the disk set has on its radially inwardly directed side a limited by the connecting channel projecting bulge, which in a region radially further outside seen in the circumferential direction smaller width than in a region radially further inside.

Ideas for embodiments of the present invention may be considered, inter alia, and without limiting the invention, as being based upon the findings and considerations described below.

Conventionally, in the rotor of an electric machine, magnets are usually accommodated within specially provided cavities or pockets which, for example, can extend longitudinally through the rotor as magnetic receiving channels. A magnetic field generated by the magnets should extend as far as possible radially outward beyond the circumference of the rotor and thus be able to interact efficiently with magnetic fields generated in the surrounding stator. If a region between circumferentially adjacent magnets is formed with a magnetizable material, however, a kind of magnetic short circuit may occur in which magnetic fields caused by the magnets do not exit the rotor as desired, but remain within the magnetizable material of the rotor. This means that the connecting the poles of the magnet Magnetic field lines are largely within the rotor, rather than extending outwardly to the stator.

It may therefore be advantageous, at least partially, not to magnetize a region between two magnets which are adjacent in the circumferential direction

To train material. For this purpose, it may be advantageous to provide in the rotor between circumferentially adjacent magnetic receiving channels each a region which does not consist of a magnetizable material and which is referred to herein as a connecting channel. Such connection channels can thus substantially avoid magnetic short circuits.

However, the connecting channels also cause that a radially outer lying outside of the rotor forming the disk set and a more inner area of the inner disk set are no longer connected to each other via a, for example, between the magnetic receiving channels extending web integrally with each other. Although such a bridge would cause the unwanted magnetic short circuit, but could also provide for a mechanical stabilization of the outer region of the plate pack. In particular, act on this outer region of the disk set at high speeds, as they can occur during operation of the electric machine, considerable centrifugal forces. Due to such centrifugal forces, deformations within the rotor and in particular in or on the mentioned

Outside areas of the disk package come. If such deformations occur plastically and / or exceed a permissible maximum dimension or even fractures occur, significant damage to the electrical machine can occur.

It is therefore suggested between two adjacent ones

Although magnetic recording channels in the rotor to provide a suitable connection channel to avoid magnetic short circuits, this

Connecting channel but in an advantageous manner to design such that it is nevertheless provided for a sufficiently high speed stability of the rotor in the electric machine. In particular, the connecting channel should be designed such that it separates the area between the adjacent magnetic receiving channels into an inner area radially inside the

Connecting channels and an outside area radially outside the

Divided channel connecting, wherein the connecting channel so geometrically should be designed so that the interior and the exterior couple form-fitting with each other.

In particular, such a form-locking coupling should take place in such a way that the inner area and the outer area are at least locally in such a way

undercut that the outside area can not be significantly removed in the radial direction of the inner area. As both the interior and the exterior of the mechanically highly resilient laminations of the

Lamellae packs can be made by such undercutting

positive coupling can be achieved that the outer region of the rotor, even at high centrifugal forces due to high speeds stable at the

Interior is kept.

In other words, two adjacent ones can exist in the rotor

Magnet receiving channels be connected to each other via a connecting channel, which forms in the longitudinal direction at least one extending radially within the magnetic receiving channels bulge, the one

Anchor portion of the disk pack encloses, which is connected via a provided between the magnetic receiving channels web portion with the outer region, wherein the anchor portion has at least one anchor portion which protrudes relative to the web portion in the circumferential direction.

In other words, a radially inwardly projecting bulge can be provided on the outer region of the disk pack, which form fit into a correspondingly complementary formed in the

Interior structure of the disk pack engages provided structure and thereby causes an undercut coupling between the outer region and the inner region. Due to this undercut coupling of the exterior including its cantilevered bulge on the one hand and the

On the inside, including its correspondingly formed structure, on the other hand, the outside area can not move substantially radially outward, even with strong centrifugal forces, but is kept mechanically stable on the inside area. With its bulge, the outer region can thus engage similar to a tie rod in the corresponding complementary structure in the inner region, so that the outer and the inner region are coupled to each other undercutting each other. The protruding bulge may in particular have a substantially T-shaped, substantially Ω-shaped or substantially fir-tree-shaped contour. All of these contours of the cantilevered bulge allow the bulge to be wider in a radially inner region than in a radially outer region. The wide radially inner region can be in a correspondingly wide

configured region of the structure in the inner region of the disk pack engage and is then prevented by the radially outermost narrower portion of this structure by an undercut positive engagement therefrom, to get out radially out of the recess out.

According to one embodiment, the magnet receiving channels and the connecting channels each extend over an entire length of the rotor. In other words, both the magnetic recording channels and the

Connecting channels from one end face of the rotor to a

rich opposite end face of the rotor. The magnet receiving channels generally have a larger cross section to the

Magnetic elements to be able to absorb it, whereas the

Connecting channels can be formed with a smaller cross-section. In this case, the magnetic receiving channels and preferably also the

Connection channels at the end faces to be open to the outside, so that for example the magnetic elements can be introduced into the magnetic receiving channels from the front side and / or from the end faces a fixing or potting compound in the magnetic receiving channels and / or the

Connecting channels can be filled.

In particular, according to one embodiment of the invention, the

Magnetic receiving channels and the connecting channels each in

Longitudinal direction be formed consistently. As a result, for example, magnetic elements of one of the end faces can be in one

Insert magnet receiving channel and then close to one

Push the opposite end face through the magnet receiving channel therethrough. Also, the fixing or potting compound can be filled in the connection channels of one of the end faces and then flow into the vicinity of the opposite end faces.

According to one embodiment, the magnet receiving channels and the connecting channels along the longitudinal direction of the rotor can be everywhere have a substantially same cross-sectional contour. This in turn can be a precise insertion and fixing of magnetic elements in the

Simplify receiving channels as well as an introduction of fixing or potting compound in the connection channels or influence in another way advantageous.

According to one embodiment, volumes within the

Magnetic receiving channels, in which no magnetic element is added, as well as volumes of the connecting channels completely with an injection-moldable

Be filled with plastic. The injection-moldable plastic can serve as a fixing or potting compound. In particular, the magnetic elements using the

Plastic firmly fixed in the magnet receiving channels. In addition, the plastic can be located between adjacent magnetic elements

Fill in connection channels and due to its non-magnetic

Prevent property there magnetic short circuits.

According to one embodiment of the invention, the plastic may be a duroplastic. Thermoset plastic materials are generally very thin before curing, in particular less viscous than most thermoplastic plastic materials. Due to this fluidity thermosets are particularly suitable for being able to flow into the narrow connecting channels and the narrow gaps between the magnetic elements received in the magnetic receiving channels and the walls of the magnetic receiving channels in order to be cured thereafter and thereby be able to fix the magnetic elements.

According to one embodiment of the invention, the plastic may in particular be fiber-reinforced. Fiber-reinforced plastics are particularly high

mechanically resilient and are therefore suitable to be able to absorb the centrifugal forces occurring within a rapidly rotating electrical machine within a rotating rotor.

According to a special embodiment of the invention, channel pairs of adjacent magnet receiving channels are V-shaped relative to a cross section through the rotor and magnetic elements in these channel pairs are arranged in a V-shape relative to the cross section through the rotor. In such a V-shaped arrangement of the magnet receiving channels and the magnetic elements received therein results in an advantageous embodiment of the rotor through The magnetic elements caused magnetic fields and thus an increased

Efficiency for the electric machine.

According to a second aspect of the invention, there is provided a method of manufacturing a rotor according to an embodiment of the first aspect of the invention described above, the method being characterized in that a plastic is inserted into the magnet receiving channels and the first

Connecting channels of the disk pack is introduced by means of an injection molding process. Due to the fact that the magnet receiving channels and the

Connection channels are preferably formed continuously and preferably extend over the entire length of the rotor, plastic can be injected in an injection molding process simply in these channels and thereby flow around the previously recorded therein magnetic elements or fill the connection channels. Thus, after curing of the plastic, the magnetic elements may be stably held in the magnetic receiving channels and the connecting channels may preferably be completely filled with non-magnetic plastic material.

It should be understood that some of the possible features and advantages of embodiments of the invention will be described herein in part with reference to an electrical machine, and more particularly its rotor, and in part with reference to a method of making the same. A person skilled in the art will recognize that the features are suitably combined, adapted or

can be exchanged to get to further embodiments of the invention.

Brief description of the drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which neither the drawings nor the description are to be construed as limiting the invention.

Fig. 1 shows a cross section through an electrical machine. Fig. 2 shows a longitudinal section through a rotor of an electric machine.

Fig. 3 shows a partial cross-sectional view through a rotor of a

advanced electrical machine. FIGS. 4 to 6 show partial cross-sectional views through rotors of electric machines according to various embodiments of the present invention

Invention.

The figures are only schematic and not to scale. Like reference numerals in the figures designate the same or equivalent

Characteristics. Embodiments of the invention

1 shows a cross section through an electric machine 10. The electric machine 10 has a stator 12 and a rotor 14 rotatably mounted relative to the stator 12. The rotor 14 for the electric machine 10 is also shown by way of example in the longitudinal section shown in FIG.

The rotor 14 has at least one disk pack 16 in

Longitudinal direction 26 of the rotor 14 stacked thin laminations 18 on. The laminations 18 are typically made of electrical steel and have been designed for use in the disk set 16 of the rotor

14 previously specially punched in shape. Centrally in the rotor 14, a shaft 24 is mounted rotatably.

Near an outer periphery of the disk pack 16 is a plurality of circumferentially 25 of the rotor 14 spaced from each other

Magnet receiving channels 20 are provided, which extend in the longitudinal direction 26 of the rotor. In the example shown, each of these

Magnetic receiving channels 20 in cross section in approximately rectangular. In the

Magnet receiving channels 20 each have at least one magnetic element 22 is arranged. Preferably, a plurality of magnetic elements 22 in

Longitudinal direction 26 in a row within a

Magnet receiving channel 20 was added. The magnetic elements 22 may be designed as permanent magnet elements, such as rare earth magnet elements. In particular, so that the magnetic elements 22 can be easily inserted from one end face into one of the magnetic receiving channels 20, the

Magnet receiving channels 20 preferably extending over the entire length of the rotor 14 and continuously formed with a constant cross-section. For this purpose, in each of the laminations 18 of the disk pack 16th be cut out suitable recesses, which then arranged in alignment one behind the other form one of the magnetic receiving channels 20. The in the

Magnet receiving channels 20 inserted magnetic elements 22 may in the magnetic receiving channels 20, for example by means of a fixing or

Grout 28 or otherwise mechanically fixed.

As can be seen in Fig. 1, is between two in the circumferential direction 25th

adjacent magnetic receiving channels 20 in the radial direction 27 further outward outer region 30 and a radially further inboard region 32 via a web portion 33 connected to each other. Both the outer region 30 and the inner region 32 as well as the web region 33 are part of the laminated core 16 formed by the laminations 18, so that the outer region 30 is connected in one piece to the inner region 32 via the web region 33. This causes on the one hand, that the outer region 30 mechanically stable at the

Interior 32 is held. Since, however, the web region 33 consists of the same magnetisable metal of the laminations 18 as the outer region 30 and the inner region 32, on the other hand a magnetic short circuit can occur via the land region 33. That is, magnetic field lines can, starting from a radially outward pole of the in a

Magnet receiving channel 20 received magnetic element 22 directly through the

Web area 33 back to a radially inwardly directed

extend opposite pole of the magnetic element 22, instead of as far as possible to extend radially outward from the rotor 14 to the stator 12. In order to avoid this, a modified rotor geometry has been proposed in the subsequently published DE 102015203018 A1. An example of such a rotor geometry was shown in fragmentary form in FIG

Cross-sectional view reproduced. Adjacent magnet receiving channels 20 are connected to each other via a connecting channel 40 filled with plastic. The web portion 33 of magnetizable material of

Sheet metal lamella 18 thus eliminated, which also gives the possibility of

magnetic short circuit in this area is avoided.

However, in this case the outer region 30 between the adjacent magnetic receiving channels 20 is no longer connected via the web region 33 to the inner area 32 which is located further radially inward. To still mechanically stabilize the outer region 30 and to the inner region 32nd

so as to avoid that the outer area 30 at high acting centrifugal forces bending radially outward, are on the

Connecting channel 40 additionally formed two so-called anchor channels 41. These anchor channels 41 engage on the one hand undercutting in the outer region 30 and on the other undercut in the inner region 32 and thus hold the outer region 30 mechanically to the inner region 32nd

However, it has been observed that in the embodiment of the connecting channels 40 shown in FIG. 3 with the additional anchor channels 41, the filled plastic material provided therein is subjected to tension when the centrifugal forces act on the outer region 30. This puts a strain on that

Plastic material strong and it must be taken if necessary precautions, so that the plastic material can permanently withstand the forces caused by the centrifugal forces can withstand. In order to avoid these problems caused by the connection and anchor channels 40, 41 subjected to tension, it is now proposed to bridge the area between two magnet receiving channels 20 adjacent in the circumferential direction 25 also by a connecting channel 40 and thus to prevent magnetic short circuits, this connecting channel However, 40 different form than in the embodiment shown in Fig. 3. In Figs. 4, 5 and 6 are

Examples of such a configuration of the connection channel 40

illustrated.

The outer region 30 of the disk pack 16 is located in

Circumferential direction 25 seen between the adjacent

Magnetic receiving channels 20 and in the radial direction 27 outside the

Connecting channel 40. At its radially inwardly directed side of the outer region 30 is limited by the connecting channel 40. The inner region 32 faces the outer region 30 with respect to the connecting channel 40 and thus for the most part radially inside the connecting channel 40. Accordingly, the inner region 32 is bounded on its radially outwardly directed side by the connecting channel 40. The connecting channel 40 is geometrically designed such that parts of the outer region 30 and parts of the

Interior 32 cooperate intermeshing and thereby couple the outer region 30 and the inner region 32 positively undercutting each other. In other words, and to be clearly seen in the various embodiments of the embodiments shown in FIGS. 4 to 6, the outer region 30 of the disk pack 16 each on its radially inwardly directed side of a limited by the connecting channel 40 projecting bulge 42, which in a Area 44 radially further outside seen in the circumferential direction 25 smaller width than in a region 46 radially further inside. The bulge 42 thus forms an anchor region surrounded by the connecting channel 40. With this bulge 42, the outer region 30 engages in a correspondingly substantially complementary formed, limited by the connecting channel 40 structure 48 or indentation in the

Interior 32 of the plate pack 16 a.

Due to the nature of the geometric configuration of the bulge 42 on the one hand and the structure 48 complementary thereto on the other hand, it can be achieved that the outer region 30 engages with its bulge 42 undercutting positively in the inner region 32 with its structure 48. By means of this undercut positive connection, the outer region 30 can be anchored and held in the inner region 32 in a manner similar to that used by a tie rod, so that it is held against outward-acting centrifugal forces.

The geometric configuration of the projecting bulge 42 on the one hand and the complementary structure 48 on the other hand is chosen so that the bulge 42 and the structure 48 are complementary in shape, but respective dimensions are chosen so that between an outer edge of the bulge 42nd and one

opposite inner edge of the structure 48 remains a continuous gap which forms the connecting channel 40. In this gap or the connecting channel 40 formed thereby can in

As part of a manufacturing process liquid plastic be injected, for example by means of an injection molding process. On the one hand, the plastic can fill in the connecting channel 40 and thus stabilize the positive connection between the outer region 30 and the inner region 32; on the other hand, the plastic can also distribute itself into the magnetic receiving channels 20 and fix the magnetic elements 22 received there after it has hardened. Due to the special configuration of the connecting channel 40 or the cantilevered bulge 42 and complementary structure 48 and the resulting undercut positive connection between the outer region 30 and the inner region 32 can be effected, that received in the connecting channel 40 plastic in on the outside

30 radially outwardly acting centrifugal forces is essentially no longer loaded on train. Instead, it is mainly in the marked in Figs. 4 to 6 undercut areas 50 to a load of the plastic received in the connecting channel 40 to pressure. Such a pressure load, the plastic can withstand much better than one

Tensile load.

Rather than burdening the plastic received in the connecting channel 40 with tension, the region 44 of the projecting bulge 42 which is located radially further outward is subjected to tension. Because these cantilevered

But bulge 42 is part of the outer region 30 of the disk set 16 and thus consists of the mechanically highly resilient material of the laminations 18, the tensile force can be well received there. In the embodiment shown in Fig. 4, the cantilevered

The bulge 42 of the outer region 30 of the lamella packet 16 is essentially in the shape of an inverted "T" .The wider region 46, ie the horizontal bar of the "T", of this cantilevered bulge 42 is located radially further inward than the narrower one Region 44, that is, as the vertical bar of the "T". Thus, the T-shaped bulge 42 may well serve as one

Art Zuganker for outdoor use 30 act to anchor it in the interior 32. In the embodiments according to FIGS. 4 to 6, two adjacent magnet receiving channels 20 are connected to one another via the connecting channel 40, which has at least one bulge running radially inwards within the magnet receiving channels 20 in the longitudinal direction of extension

42, which encloses an armature region 42 of the disk set, which connects via a provided between the magnetic receiving channels 20 web portion 44 with the outer region 30, wherein the anchor portion 46 has at least one anchor portion 46 which protrudes relative to the web portion 42 in the circumferential direction.

In Fig. 5, an embodiment is shown, in which the cantilevered

Bulge 42 has a substantially fir-tree-shaped contour. Radially further inward-branch-like regions 46 of this pine tree have a larger width than a radially outermost region 44, so that here again a tie rod function can be achieved.

In the embodiment shown in Fig. 6, the cantilevered

Bump 42 has a shape of an upside-down ".OMEGA." Even in such a configuration, the desired undercut interlocking coupling between the outer region 30 and the inner region 32 can be effected.

In all the illustrated embodiments, the bulge 42 of the

Outside in the structure 48 of the inner region 32 undercutting a. Recorded in the intermediate connecting channel 40

Plastic material is loaded mainly in the undercut areas 50 mainly on pressure instead of train and thus can withstand higher loads. The outer region 30 is thus held in a Zuganker-like manner in the inner region 32 of the plate pack 16.

As shown, the adjacent magnetic receiving channels 20 may each be combined into channel pairs 52, with a connecting channel 40 each extending between the magnetic receiving channels 20 of such a channel pair 52. The magnet receiving channels 20 may advantageously be arranged in a V-shape and the connecting channel 40 may each connect radially further inwardly located ends of the two magnetic receiving channels 20 with each other. In this way, an advantageous for the efficiency of the electric machine 10 magnetic field in the rotor 14 can be generated.

Claims

claims

A rotor (14) of an electric machine (10), comprising:

at least one plate pack (16) with laminations (18) stacked on top of one another in the direction of longitudinal extent (26) of the rotor (14),

wherein a plurality of extending in the longitudinal direction of the rotor (14) and close to an outer periphery of the disk pack (16)

Circumferential direction (25) of the rotor (14) spaced from each other

Magnetic receiving channels (20) is provided, in which in each case at least one magnetic element (22) is arranged,

characterized in that

two adjacent magnetic receiving channels (20) via a

Connecting channel (40) are interconnected such that a

Outer region (30) of the disk pack (16) on its radially inwardly directed side delimited by the connecting channel (40)

projecting bulge (42) which in a region (44) radially further outside seen in the circumferential direction (25) smaller width than in a region (46) radially further inside.

2. rotor (14) according to claim 1, wherein the outer region (30) with his

cantilevered bulge (42) and a radially further inside arranged inner region (32) are undercut each other positively interlocking with each other.

3. rotor (14) according to claim 1 or 2, wherein the protruding bulge (42) has a substantially T-shaped, substantially Ω-shaped or substantially fir-tree-shaped contour.

4. Rotor (14) according to one of claims 1 to 3, wherein the

Magnetic receiving channels (20) and the connecting channels (40) each extend over an entire length of the rotor (14).

5. Rotor (14) according to one of claims 1 to 4, wherein the

Magnet receiving channels (20) and the connecting channels (40) in the longitudinal direction of extension (26) are formed continuously.

6. Rotor (14) according to one of claims 1 to 5, wherein the

Magnetic receiving channels (20) and the connecting channels (40) along the longitudinal direction (26) of the rotor (14) everywhere in the

Have substantially the same cross-sectional contour.

7. rotor (14) according to one of claims 1 to 6, wherein volumes within the magnetic receiving channels (20), in which no magnetic element (22) is received, as well as volumes of the connecting channels (40) are completely filled with an injection-moldable plastic.

8. Rotor (14) according to claim 7, wherein the plastic is a thermosetting plastic.

9. rotor (14) according to claim 7 or 8, wherein the plastic is fiber-reinforced

10. Rotor (14) according to one of claims 1 to 9, wherein channel pairs (52) of adjacent magnetic receiving channels (20) with respect to a cross section through the rotor (14) are arranged V-shaped, and

wherein magnetic elements (22) in channel pairs (50) with respect to a cross section through the rotor (14) are arranged in a V-shape.

11. Electrical machine (10) comprising:

a stator (12) and

a rotatably mounted relative to the stator rotor (14) according to one of claims 1 to 10.

12. A method of manufacturing a rotor (14) according to one of

preceding claims 1 to 10,

characterized in that

by means of an injection molding process, a plastic in the

Magnetic receiving channels (20) and the connecting channels (40) of the

Lamella packages (16) is introduced.