WO2019025360A1

WO2019025360A1 - Injected-cage rotor

Info

Publication number: WO2019025360A1
Application number: PCT/EP2018/070583
Authority: WO
Inventors: Sébastien Porcher; Thierry VISSE; Stéphane BOULIN; François TURCAT
Original assignee: Moteurs Leroy-Somer
Priority date: 2017-07-31
Filing date: 2018-07-30
Publication date: 2019-02-07
Also published as: FR3069734A1; FR3069734B1

Abstract

The rotor of a rotary electric machine, comprising: – a bundle of magnetic laminations defining slots each having first and second opposite long sides, oriented substantially radially, – bars (10) of a first electrically conducting material housed in the slots, occupying just a portion of the cross section of the slots and each coming to bear, over at least part of their length, on just one of the said long sides at a time, leaving a space to the opposite face, and – a second electrically conducting material, different from the first, injected into the slots and present in the said space.

Description

CAGE ROTOR INJECTED

The present invention relates to rotating electrical machines and more particularly the rotors of such machines.

Background

Asynchronous electric motors conventionally comprise a packet of magnetic sheets traversed by notches. Aluminum is injected under pressure to form bars which are connected to the outside of the sheet bundle by short-circuit rings.

To improve the electrical performance, it may be interesting to further reduce the electrical resistivity of the bars by replacing the aluminum with copper. However, the melting temperature of copper being much higher than that of aluminum, it becomes difficult to inject copper into the notches.

A known solution is thus to introduce copper conductor bars into the notches and to inject aluminum under pressure to fill the space left free inside the notches by the bars.

The application WO2011015494 discloses a rotor comprising a bunch of inclined sheets.

Applications WO2011020718, WO2010100007, WO2009038678, US2011291516, WO2014067792, WO2015071156, WO2012041943, JPH10234116, CN1925280, JPH11206080, JP2005278373 and JPH1028360 disclose rotors whose laminations have notches receiving copper bars and into which aluminum is injected. under pressure.

JP 20102-68561 discloses a rotor comprising a pack of sheets formed by a radially inner portion and a radially outer portion and having notches having a width greater than that of the copper bars. During the manufacture of the rotor, an upper part of the packet is shifted to the left while a lower part of the packet is shifted to the right. The aluminum is then injected into the notches.

There is a need to further improve the performance of rotating electrical machines.

summary

The subject of the invention is a rotary electric machine rotor, comprising: a bundle of magnetic sheets defining notches each having, in a view perpendicular to the axis of rotation, first and second large opposite sides oriented substantially radially,

bars of a first electrically conductive material received in the notches, occupying only a portion of the section of the notches and each bearing at least a portion of their length on one of said long sides at a time, opposite face a space, and

a second electrically conductive material, different from the first, injected into the notches and present in said space.

Compared to the solution disclosed in the application WO 20110154594, the section of the copper bar allows inclination of the package of sheets without constraining in shear bar or with less stress. A straight bar eliminates conventional inter-bar currents and the losses associated with them.

When mounting, for example by fitting, the sheet bundle with the free bars in their notches on an inclined mandrel, there is shear force of the bars contributing to their maintenance within the package and a partial deformation according to the desired inclination . This is how each bar is in contact only with a large side of the notch at its ends.

The injection of the second electrically conductive material into the space provided between the face of the bars opposite to that by which the bars bear on one side of the notches and the other side of the notches reduces the pressure during the operation. injection, and thus facilitates this injection step. This also reduces the extent of contact between the sheets and the bars.

The bars have two opposite main faces which each bear on a respective large side of a notch. The bars have for example in cross section a substantially trapezoidal shape.

The free mounting clearance which aids the tilting of the sheet bundle, ie the play, measured in a plane perpendicular to the axis of rotation of the rotor, between the side of the notch opposite to that on which the bar bears on one main face and the other main face of the bar, is preferably between 0.5 mm and 10 mm at the longitudinal ends of the bars. This game can be modified according to the size of the machine and that of the notch. The bars may each provide in at least one cross section, with the large side of the notch opposite that with which it bears, a set of constant width.

All the bars can come in a cross section of the at least one sheet of metal, resting against the first long sides of the notches.

The sheets can be stacked on the same shaft with a variable inclination to optimize the harmonic rate of torque produced by the electric machine thus produced. The package of sheets can be twisted so non-uniformly. For example, the angular offset between two sheets may be different depending on the position of the sheets along the axis of rotation of the rotor.

Preferably, an angular offset between at least two adjacent plates of one half of the package including an axial end thereof is different, in absolute value, from an angular offset between at least two adjacent plates of another half of the package. For example, at least one sheet does not come into contact with any major surface of at least one bar.

Preferably, the bars are not initially deformed before being installed in the notches.

The notches can be helical.

The second material can fill the entire section of the notches on the outside of the bars.

Preferably, the magnetic sheets comprise a magnetic steel, for example iron / silicon, with its different shades. The thickness of each sheet is for example between 0.35mm and 0.65mm.

The bars can be introduced with a relatively large clearance in the notches. The presence of such a clearance is advantageous because it makes it possible to use extruded bars having a manufacturing tolerance larger than machined bars, but being less expensive to produce.

The subject of the invention is also a process for manufacturing a rotary electric machine rotor, particularly as defined above, comprising the steps of:

- manufacture by punching or laser magnetic laminations of the rotor,

- forming the package of rotor plates by superimposing the magnetic sheets,

- insert bars of the first material into the notches of the sheet package, - angularly shift the sheets to cause shearing and / or partial deformation of the bars present in the notches,

- inject the second material into the notches.

Description of figures

Other features and advantages of the present invention will become apparent on reading the following detailed description, non-limiting examples of implementation thereof, and on examining the appended drawing, in which:

FIG. 1 is a schematic and partial axial section of an exemplary rotor according to the invention,

FIGS. 2A to 2C show, in partial view, sections according to the plans A-

A, B-B and C-C of the rotor of FIG.

FIGS. 3 and 4 show a notch embodiment detail,

FIGS. 5 and 6 show variants of a rotor cage, and

- Figure 7 shows schematically, in axial section, an alternative embodiment of the rotor according to the invention.

Rotor

FIG. 1 shows a rotor 1 according to the invention. This rotor 1 comprises a pack 2 of magnetic sheets 113, mounted on a shaft 9, for example made of steel, of axis X.

Package 2 is formed by the superposition of magnetic sheets 113 in which perforations 3 are cut.

The superposition of the openings 3 of the plates 113 forms, within the pack 2, notches 4 which extend longitudinally from one axial end of the pack 2 to the other. The notches 4 may be straight, that is to say that all the sheets 113 are exactly superimposed without angular offset from one sheet 113 to the next. However, preferably, the plates 113 are superimposed by being angularly offset slightly from one sheet to the next so that the longitudinal axes of the notches 4 follow a helical path about the axis of rotation of the rotor, in a manner known in the art. itself.

In the example shown, all the plates 113 are identical and the openings 3 are also, so that the package 2 has identical notches 4. In variants, the package 2 is formed by assembling plates 113 which are not strictly identical in front view, of the front of the package 2, so that the section of a notch 4 may have a shape that varies when moving from the front end of the notch 4 to the rear end. The rotor 1 comprises bars 10 made of copper, introduced into the notches 4, and a material 20 such as aluminum, injected into the notches 4 in the space left free by the bars 10.

Short-circuit rings 120 and 130 are molded from aluminum at the ends of the pack of sheets 2. These rings 120 and 130 are in one piece with the aluminum cast in the notches 4.

According to the invention, the bars 10 occupy only a portion of the section of the notches 4.

In the illustrated examples, the bars 10 have in cross section a substantially trapezoidal shape and bear, for at least a part of their length /, each on one of the long sides 4a of a notch 4 by one or the other of the main faces 11.

As illustrated in Figure 2A, the bars may each provide in at least one cross section, with the long side of the notch opposite that with which it bears, an interval d of constant width.

At least a portion of the openings may have on one of the opposite large sides 4a relief notches 5, the bars 10 bearing by at least one main face 11 against said reliefs. The plates 113 may have reliefs on one and / or the other of the long sides according to their position along the axis of rotation of the rotor.

The reliefs 5 may, by decreasing the contact area between the bars 10 and the sheets, reduce the inter-bar currents flowing in the sheets and the corresponding energy loss by Joule effect.

These reliefs 5 can be made very precisely during the cutting of the sheets, and allow greater tolerance of bar manufacture.

The reliefs may be in the form of bosses, preferably extending over substantially the entire radial dimension of a bar 10.

The bosses 5 may have an amplitude h of between 0.2 and 0.4 mm, for example 0.3 mm, and the radius of curvature R at their apex is, for example, between 0.4 and 0.6 mm, being example of 0.5mm, as shown in Figure 2A.

Notches with blocking reliefs

As illustrated in FIGS. 2A to 2C, the notches may have at least one locking relief 30 bearing against a radially outer end face of a corresponding bar 10, better two such opposing reliefs 30 each bearing against the same end face.

Hollow bars

One or more of the bars may be hollow.

In the variant illustrated in Figure 4, the bars 10 each have a longitudinal inner cavity 17 which is filled by the second material.

The fact that the bars are hollow facilitates the filling of the cavity for molding the rear shorting ring, when the injection takes place from the front.

In addition, the total amount of copper used may be less, which reduces the cost of the machine.

The second material that is injected into the bars 10 is protected from contact with the oxygen of the air by the material of the bars, except at the axial ends thereof. In this way, the corrosion phenomena at the interface between the first and second materials are limited.

The bars 10 preferably have, in cross section, a closed contour, which may be non-circular.

Preferably, the second material 20 fills the notches also outside the bars.

The bars 10, hollow or not, may extend over the entire radial dimension of the notches 4.

Alternatively, the bars 10, hollow or not, have a radial dimension which is less than that of the notches.

Bars 10, hollow or not, may extend over at least the length of the sheet package.

All the notches 4 of the rotor may have hollow bars 10 with the second material 20 injected therein. Alternatively, some notches 4 may not have bar 10, being in this case fully filled by the second conductive material. The rotor comprises for example more notches with bars than slots without bar, or vice versa.

Number of bars less than the number of notches

In the variant illustrated in FIG. 6, the bars 10 are present in only part of the notches 4. The absence of bars 10 in certain notches 4 keeps a larger total section for the passage of the injected aluminum, and thus facilitate the filling of the rear ring when the injection is done from the front.

The presence of bars 10 in a material of lesser electrical resistance such as copper in some notches improves electrical performance. It is possible, by choosing the number of bars added, to optimize the increase of performances with regard to the cost of the machine, the copper being more expensive than the aluminum.

The rotor may comprise more notches 4 with bars 10 than slots 4 without bar 10. In other variants, it is the opposite and the rotor has more notches 4 without bar than bar.

Multiple arrangements of the bars within the slots 4 are possible. For example, a notch barless and a bar notch may be alternated circumferentially. It is also possible to alternate more generally no notches without bar with n2 notches with bar, ni and n2 being integers strictly greater than 1.

Auxiliary notches

As illustrated in FIG. 5, the openings can form, within the package, n main notches 4 as defined above and m secondary notches 40, radially inner with respect to the main notches, with n and m being non-zero integers and n> m.

Thanks to the secondary notches 40 of a larger passage section for the second conductive material, during the injection. The latter being injected from the front, the fact of having a larger passage section ensures faultless realization of the rear short ring.

In the variant illustrated in FIG. 5, each secondary notch 40 communicates with a main notch 4.

In a variant, the secondary notches 40 are disjoint from the main notches 4.

Each secondary notch 40 may be centered on a median plane M of a main notch 4.

The ratio n / m between the number of main notches 4 and the number of secondary notches 40 is for example equal to 2 or 3.

The secondary notches 40 preferably have an angular extent, measured around the axis of rotation of the rotor, greater than that of a main notch 4. The package may comprise, as illustrated in FIG. 7, at least one guard plate 110 at at least one of its axial ends, preferably at each end of the package 2 of plates 113.

These guard plates 110 are configured to allow, on the one hand, the injection of aluminum into the notches 4 of the pack 2 of magnetic sheets 113 and, on the other hand, to axially retain the bars 10 in the notches 4, the bars coming into support at their ends on the guard plates 110.

These guard plates 110 can also protect the axial ends of the bars 10 of oxygen from the air and thus avoid corrosion phenomena at the interface between aluminum and copper.

The guard plate (s) 110 can be made with perforations 220 which allow injection through the guard plate 110 of the second material 20 into the pack 2 of sheets 113. The guard plate (s) 110 may comprise at least one retaining relief 221 superimposed at least partially on the bars to retain them axially. This or these support reliefs 221 can be made in various ways.

For example, the retaining reliefs or reliefs 221 comprise two advances facing one notch receiving a bar. In variants, the retaining reliefs or reliefs 221 comprise a notched material bridge receiving a bar.

Rotor manufacturing

To manufacture the rotor, it is possible to cut the sheets 113 with a press equipped with a punch or with the laser and to form, during the cutting, perforations 3 corresponding to the first and second series of notches 4 and, if appropriate, the notches secondary 40 and bosses 5.

Then, the plates 113 are superimposed to form the package 2 and the bars 10 are inserted into the notches 4. Once the bars 10 in place, we can shift the plates 113 to twist the rotor. Preferably, the angular offset between the end plates is between 0 ° and 4 °. Then, one can proceed in a press to the injection of the second material 20, namely aluminum. It is possible, during the injection, to produce the short-circuit rings by molding.

Of course, the invention is not limited to the examples which have just been described.

For example, the notches may have other shapes, as well as the bars. Other materials than copper and aluminum can be used.

Claims

1. Rotating electrical machine rotor comprising:

- a package (2) of magnetic sheets (113) defining notches (4) each having first and second large opposite sides, oriented substantially radially, the notches (4) being helical.

- bars (10) of a first electrically conductive material received in the slots, occupying only a portion of the section of the notches and each bearing at least a portion of their length on only one of said long sides at a time, arranging with the opposite face a space (41), and

- A second electrically conductive material (20), different from the first, injected into the notches and present in said space.

2. Rotor according to claim 1, the bars (10) having two main faces (11) and each bearing on one of the long sides (4a) of a notch (4), by one or the other of said main faces (11).

3. Rotor according to claim 2, the bars (10) having in cross section a substantially trapezoidal shape.

4. Rotor according to any one of claims 1 to 3, the bars (10) each forming in at least one cross section, with the long side (4a) of the notch (4) opposite to that with which it comes in. support, a set of width (d) constant, preferably between 0.5mm and 10mm.

5. Rotor according to any one of the preceding claims, all the bars (10) coming in a cross section of the pack (2) of sheets (113) at least, resting against one of the first long sides (4a) of notches (4).

6. Rotor according to any one of the preceding claims, the first material being copper.

7. Rotor according to any one of the preceding claims, the second material (20) being aluminum.

8. Rotor according to any one of the preceding claims, the second material filling the entire section of the notches (4) outside the bars (10).

9. Rotor according to any one of the preceding claims, the bars (10) having a radial dimension less than that of the notches (4).

10. Rotor according to any one of the preceding claims, the angular offset between the end plates (113) being between 0 ° and 4 °.

11. Rotor according to any one of the preceding claims, the package (2) of sheets (113) being twisted non-uniformly.

Electric rotating machine comprising a rotor according to any one of the preceding claims.

13. A method of manufacturing a rotary electric machine rotor as defined in any one of claims 1 to 11, comprising the steps of:

- manufacturing by punching or lasering magnetic laminations (113) of the rotor,

- forming the package (2) of sheets (113) of the rotor by superimposing the magnetic sheets (113),

- insert bars (10) of the first material in the notches (4) of the package (2) of sheets (113),

angularly shifting the plates (113) in order to cause shearing and / or partial deformation of the bars (10) present in the notches (4), along a helical path around the axis of rotation of the rotor

injecting the second material (20) into the notches (4).