WO2019007662A1

WO2019007662A1 - Rotor having a reinforced rotor cage

Info

Publication number: WO2019007662A1
Application number: PCT/EP2018/065926
Authority: WO
Inventors: Paul Kainzinger; Gereon Johannes Pusch
Original assignee: Magna powertrain gmbh & co kg
Priority date: 2017-07-05
Filing date: 2018-06-15
Publication date: 2019-01-10
Also published as: DE102017211414A1

Abstract

The invention relates to a rotor (10) for an electric motor, comprising a shaft (12) that extends in the axial direction, a main body (20) that is formed from a multiplicity of metal disks (22) and is arranged on the shaft (12), wherein a metal disk (22) has slots (24) which extend radially inward from the outer region of the metal disk, and a cast squirrel cage (14), which is arranged around the main body (20); wherein the rotor (10) also has at least one insert part (30) which has at least a first connecting ring (32a, 32b) and projections (34a, 34b), which are arranged circumferentially on the connecting ring (32a, 32b) and extend in the axial direction into the slots (24) of the metal disks (22), and wherein the insert part (30) is fixed to the main body by the squirrel cage.

Description

Rotor with reinforced rotor cage

Field of the invention

The invention relates to a rotor comprising a rotor cage reinforced by an insert, and to a method of manufacturing such a rotor. State of the art

Rotors for electric motors, for example for asynchronous motors, have one

Main body, which consists of several layered metal discs, which are surrounded with a casting material. The metal discs are provided with radial slots which extend from the outside inwards. The metal discs are placed in the package and pushed onto the shaft. After that you will be together with the wave

poured to create a so-called short-circuit cage. The disks can be easily pushed in the circumferential direction offset from each other so that the grooves on the surface of the rotor are helical. The casting material flows into the slots of the discs and after curing, the rotor is fixed in and through the cast short cage.

The problem with such short circuit cages is not always sufficient strength at high speeds, so that damage can occur in the short circuit cage. To avoid such cracks, for example, the cages can be made of a higher strength material by using another casting material. The disadvantage here is that the conductivity of the cage decreases and thus the performance of the asynchronous motor having such a rotor. An alternative would be to not cast the cage but, for example, to manufacture the shorting rings and the bars separately and then to assemble and solder the individual elements. Again, however, suffers the conductivity of the short circuit cage noticeably and the installation of such elements is associated with a not inconsiderable additional effort. It is also possible to stabilize the cage at the edges (the axial ends) of the main body with attached rings. Such "armor" can for example be welded or shrunk to the short-circuit cage, which, however, in the manufacture of the rotor, a further quite complex process step is necessary. Presentation of the invention

Object of the present invention is a rotor with a solid and stable

To provide a short cage, which is easy to manufacture. The object is achieved by a rotor according to claim 1 and by a

Manufacturing method according to claim 8.

An electric motor rotor according to the present invention comprises a shaft extending in the axial direction, a main body formed of a plurality of metal disks and disposed on the shaft, a metal disk having slots radially extending from the outer portion thereof extend inwardly, a molded shorting cage disposed about the main body, the rotor further comprising at least one insert having at least a first connecting ring and projections which are circumferentially disposed on the ring and in the axial direction in the slots of the metal discs extend and the short-circuit cage fastened the insert and the main body. Circumferential does not mean that the projections must be arranged on the outer edge of the connecting ring. They may also be provided on the side arranged in the axial direction. The projections are preferably finger or pin-shaped. By inserting a higher strength of the short-circuiting cage is achieved, since only the insert can be made of a higher-strength alloy than the remaining short-circuit cage. The higher-strength alloy is therefore present only in the area where a higher strength is necessary. The remaining volume of the slots is then still filled with the better conductive casting material of the shorting cage. The

Cast material is usually especially pure aluminum, since the conductivity is good and the weight low. Other materials such as, but copper are possible. The insert is therefore preferably a stronger aluminum alloy, for example

AISi9Cu3 (Fe) or AISM OMg (Fe), but is not limited to these. For example, a copper alloy such as KuCrZi could be used. It is also conceivable that the casting material and the insert are not made of the same base material, so that, for example, a copper alloy insert is combined with a cast aluminum material (or vice versa).

The insert member may further comprise a second connection ring concentrically disposed radially further inward or radially outward of the first connection ring, and circumferentially arranged projections extending in the axial direction into the slots of the metal disks. With two connecting rings, it is possible to adequately reinforce both the outer and inner portions of the slots. The inner one

Connecting ring is preferably connected to the outer connecting ring via webs, which are preferably arranged circumferentially offset. Preferably, these webs are arranged on the connecting ring, but it is also possible to provide the webs on the projections, so that the webs are arranged in the slots of the rotor main body. This facilitates the preparation of the casting process, as the connecting rings can be positioned more easily.

The projections of the connecting ring or rings may have a length in the axial direction, which corresponds to 0.2-1, 5 times the length of the radial slot of the metal disc. This will provide a reasonable ratio of projection length and

Metal disc construction defined, which simplifies the production of various inserts for different applications.

Preferably, the projections of the (if it is only a connecting ring) or the connecting rings are provided on an outer portion and / or an inner portion of the slot. There, the support effect of the projections works best.

At the insert are preferably provided at the transition between the projection and connecting ring fillets. These fillets improve the strength and the

Service life of the rotor by avoiding stress peaks at the edges and preventing cracking in the cast material. Preferably, the fillets on the insert do not extend completely around the projection but leave a small wall on the radially inner side of the connector ring. These walls ensure that when pouring the rotor main body that

Casting material can not leak at the fillets, since they are against the

Impact rotor main body. The projections of the insert or parts have a complementary to the slots outer contour. In particular, the slot walls and the projections are laterally in contact with each other. This facilitates the positioning and fixing of the insert for the casting process. However, it can also be provided that the projection has a dimensioning which is less than the corresponding dimensioning in the slot of the metal disk, so that the projection can be pushed without contact into the slot. Such a configuration is provided in particular when the

Metal discs are mutually offset in the circumferential direction.

The invention further includes a method of manufacturing such a rotor, comprising the steps of providing a shaft, applying a rotor main body to the shaft by sliding radially slotted metal discs, inserting projections of an insert into the slots, and molding the main body and insert a casting material. Brief description of the figures

Figure 1 shows a longitudinal section through a rotor according to the invention Figure 2 shows a side view of the rotor; Figure 3 shows a front view of an insert; Figure 4 shows a sectional view of an insert;

Figure 5 is an isometric view of an insert; and FIG. 6 shows a front view of a metal disk. Description of the Preferred Embodiments

In the following, the terms "axial", "radial" and "circumferential" are used. Axial is a direction along the longitudinal axis (right and left in Figure 1), Radial one

Direction perpendicular to the longitudinal axis (top and bottom in Figure 1) and circulating means around the axis.

FIG. 1 shows a longitudinal section of the rotor 10 after production. The main body 20 is seated on a shaft or hollow shaft 12. On at least one edge of the main body 20, an insert 30 is provided, in Figure 1 are at both axially opposite ends respectively an insert 30. The insert 30 is together with the main body 20 in a short circuit cage 14 poured.

The main body 20 includes a plurality of metal discs 22 juxtaposed on the shaft 12 as a package. The metal discs 22 have a bore in the middle, so that they can be pushed onto the shaft 12. In order to define the axial position of the metal discs 22 and thus the main body 20, the shaft 12 may have a shoulder (not shown) as a stop or a groove for a stopper ring. In order to ensure an anti-rotation of the metal discs 22, the metal discs 22 are either placed or joined with a corresponding fit on the shaft 12, or have a positive inner contour, such as groove and

Spring, or a star, or tooth-shaped, polygonal (square, hex, etc.) or otherwise positive fit with the shaft 12 on. The main body 20 of a plurality of metal discs is also referred to as a laminated core.

A preferred embodiment of a metal disk is shown in FIG. Slots 24 extend in a radial direction in a metal disk 22. These slots 24 are provided, inter alia, for the casting material to run into them

To produce a short-circuit cage and the main body 20 formed from the metal discs to fix, in Figure 6 it can be seen that the slots 24 to the edge of the

Metal disc 22 extend, so that the metal disc 22 has openings at the edge. In the present case, the slots create a narrow opening at the edge, then widen and taper radially inwardly towards the axis of rotation until they preferably terminate in a radius. Such metal discs 22 are usually made of steel, in particular a material which is called electrical steel.

To line up the metal discs 22 there are two main uses. First, the metal discs 22 can be put together congruently so that the slots 24 of the metal disc 22 form a straight groove within the

Training main body. And second, the metal discs can be easily twisted when juxtaposed, so that the slots form a slightly screwing groove, called a helix. In particular, the offset is selected such that over the axial length of a rotor essentially a rotation about the mean distance A of two slots 24 results. In the present embodiment, shown in FIG. 2, the metal discs 22, lined up against each other, form one on the surface of the disc when aligned through the narrow opening at the edge which the slot produces at the edge of the metal disc

Main body visible groove 26. This is called an "open groove" 26. In another embodiment, the slots 24 are not in the edge of the metal disc 22nd

formed what is referred to as a "closed groove".

The insert 30 has at least one connecting ring 32a, 32b, from which a plurality of projections extend in the axial direction. The connecting ring is dimensioned such that the projections extend into the slots of the metal discs at the areas relevant for the reinforcement. Preference is given to the inner region. The projections may be (slightly) curved or narrower than the slot 24 dimensioned so that the orientation of the pushed metal discs 22 may be slightly offset and the groove 26 in the main body 20 screwed about the longitudinal axis of the shaft 12 (helix). In the preferred embodiment, which is also shown in the figures, however, the (open) groove 26 is straight. This is also the case

Projections 34a, 34b formed straight, which facilitates the manufacture of the insert 30. The relevant areas are at the top and bottom end of the slot. A single connecting ring is therefore preferably arranged so that the projections 34a, 34b, are provided at the upper or lower end portion of the slot 24 and project there into the slot. In particular, the projections are arranged at the upper and at the lower end of the slot 24 and contact this. Further, the projections 34 a, 34 b are formed in a complementary shape to the slot ends, so that the respective Projection 34 a, 34 b contacted the inside of the slot 24. In the preferred

Embodiment, the projection 34a also fills the slot at the edge of the metal disk 24, so that the projection 34a smoothly merges into the surface of the main body.

In particular, a projection 34a, 34b has a length in the axial direction which corresponds to 0.2-1.5 times the length of the radial slot 24 of the metal disk. Further preferred minimum lengths are 0.5 or 0.9 times the length of the slot, while the maximum lengths are preferably 1, 3 or 1.1. In a further preferred embodiment, the length of the projection 34a, 34b is substantially equal to the length of the radial slot 24. That is, the length of a projection 34a, 34b may be determined by the length of the radial slot 24.

Only one connecting ring 32a, 32b may be provided (preferably the inner one), but it is preferred that the insert 30 comprises two connecting rings 32a, 32b, a radially outer connecting ring 32a, and a radially inner connecting ring 32b, respectively outer and inner projections 34a, 34b have. The inner connecting ring 32 b is preferably connected to the outer connecting ring 32 a via webs 31. This simplifies the assembly and alignment of the connecting rings 32a, 32b prior to the casting process.

The insert 30 is preferably provided on both axially opposite sides of the main body 20 so that the rotor 10 is symmetrically reinforced. The outer diameter of the rotor 10 is further characterized by the outer diameter of the

Metal discs 22 set. That an outer connecting ring 32a (and also the

Outside surface of the projection 34 a) should have a maximum outer diameter, which is flush with the metal plate 22, but it may also be smaller.

At the transition between connecting ring 32a, 32b and projection 34a, 34b are preferably rounded 36 provided to avoid voltage spikes. These fillets can be seen in Figures 3 and 5. These fillets 36 take some material from the connecting ring. In one embodiment, the fillets 36 may not extend all the way around a projection, such that at the inner edge of the outer

Connecting ring 32 a between the projections 34 a and / or at the outer edge of the inner connecting ring 32 b between the projections 34 b remain walls. In the casting process, these walls 35 prevent leakage of the casting material by contacting the main body.

In the manufacture of the rotor, first, the metal disks 22 are lined up and fixed together to produce the main body 20 as a laminated core. The fixing is usually done with a tool that holds the main body 20 together. As As mentioned, the metal discs 22 may be straight or helical and form either an open or a closed groove 26. The main body 20 is then pushed onto a shaft 12. The main body can then be fixed on the shaft, for example. With a stop and a clamping ring. Then, the inserts 30 are placed on the main body 20. The attachment of the inserts 30 may be provided via a corresponding fit of some or all of the projections 34a, 34b and slots 24, but may also be done by a separate operation, for example. By spot welding or soldering or by an additional tool such as a clamp or the mold described below. Then, the casting is placed around the insert, which either rests directly on the insert, or includes this. In the embodiment shown in the figures, the connection rings 32a, 32b and the projections 34a, 34b are in contact with the mold such that the outer surface and the inner surface of the shorting cage are flush with the respective surfaces of the connection rings 32a, 32b and the projections 34a, 34b are. As already mentioned, the outer surface of the rotor is fixed by the main body 20 and the metal disks 22, respectively. The casting mold abuts radially on the outer surface of the main body 20 and axially on the side surfaces of the main body 20, with the radially inner wall of the casting mold inside the inner end of the slot 24

Metal disc 22 should be so that the casting material does not leak. Then, the main body 20 and the inserts 30 become with the molding material

is formed, whereby the so-called short-circuit cage 14 is formed, which receives the main body 30 and the or the insert (s) 30 and fixed. The casting material is preferably pure aluminum or copper, while the insert is made of a stronger aluminum alloy or copper alloy, for example AISi9Cu3 (Fe), AISM OMg (Fe) or KuCrZi. Although this reduces the conductivity of the insert, the strength of the insert is significantly higher than that of the cast material. Since the insert 30 is located only at the edge of the main body 20, the electrical conductivity of the entire rotor 10 does not appreciably suffer, but the strength is increased precisely at the critical points, resulting in an increased life of the rotor. LIST OF REFERENCES:

Rotor 10

Wave 12

Cast material 14

Main body 20

Metal disc 22

Slot (in the metal disc) 24 groove (in the main body) 26 insert 30

Footbridge 31

outer connecting ring 32a inner connecting ring 32b outer projection 34a inner projection 34b

Wall 35

Rounding 36

Claims

claims

1 . A rotor (10) for an electric motor, comprising a shaft (12) extending in the axial direction; a main body (20) formed of a plurality of metal discs (22) and disposed on the shaft (12), a metal disc (22) having slots (24) extending radially inwardly from the outer portion thereof; and a molded shorting cage (14) disposed around the main body (20); characterized in that the rotor (10) further comprises at least one insert (30) having at least a first connecting ring (32a, 32b) and projections (34a, 34b) circumferentially disposed on the connecting ring (32a, 32b) and extending in the axial direction in the slots (24) of the metal discs (22), and wherein the insert part (30) through the

Short circuit cage is attached to the main body.

A rotor (10) according to claim 1, further comprising a second connecting ring (32a, 32b) disposed concentrically with the first connecting ring (32a, 32b) and having projections (34a, 34b) circumferentially in the axial direction in the slots (24) of the metal discs (22) extend.

3. rotor (10) according to claim 2, wherein the inner connecting ring (32 b) with the outer connecting ring (34 b) are connected by webs.

A rotor (10) according to any one of the preceding claims, wherein the projections (34a, 34b) of the one or more connecting rings (32a, 32b) are provided at an outer portion and / or an inner portion of the slot (24).

5. Rotor (10) according to any one of the preceding claims, wherein the projections (34 a, 34 b) of the one or more connecting rings (32 a, 32 b) have a length in the axial direction, the

0.2 - 1, 5 times the length of the radial slot (24) of the metal disc (22).

6. rotor (10) according to any one of the preceding claims, wherein the insert (30) at the transition between projection (34a, 34b) and connecting ring (32a, 32b) roundings (36) are provided.

A rotor (10) as claimed in any one of the preceding claims, wherein the fillets (36) are not provided completely around the respective projection (34a, 34b).

A rotor (10) according to any one of the preceding claims, wherein the projections (34a, 34b) of the insert (s) (30) have a shape complementary to the slots (24).

A method of manufacturing a rotor (10) according to any one of the preceding claims, comprising the steps of: providing a shaft (12);

Preparing the main body (20) by assembling and fixing metal discs (22) provided with radial slots (24);

Applying the main body (20) to the shaft (12);

Attaching at least one insert member (20) to the main body (20) so that projections (34a, 34b) of the insert member (30) project into the radial slots (24); and

Pouring the main body (20) and the insert (30) with a casting material.