STATOR FOR A ROTARY ELECTRIC MACHINE

Abstract

A stator for a rotary electric machine has: a toothed ring with teeth defining notches therebetween, the notches being open radially toward the outside, windings, which are arranged in a distributed manner in the notches, electrical conductors being arranged in an aligned manner in the notches, and a yoke mounted onto the toothed ring.

Claims

1. A stator for a rotary electric machine, comprising: a ring gear having teeth that define slots between one another that are open radially toward the outside, windings that are disposed in a distributed manner in the slots, having electrical conductors that are disposed in an arranged manner in the slots, and a yoke attached to the ring gear.

2. The stator as claimed in claim 1, wherein at least one slot is closed on the air gap side by a tangential bridge that connects two consecutive teeth of the ring gear together.

3. The stator as claimed in claim 1, wherein at least one slot has edges that are radially parallel to one another.

4. The stator as claimed in claim 1, wherein at least one slot has a rectangular or hexagonal cross.

5. The stator as claimed in claim 1, wherein at least one tooth have a trapezoidal overall shape in cross section.

6. The stator as claimed in claim 1, wherein the electrical conductors present in the slots have a circular or rectangular section.

7. The stator as claimed in claim 1, wherein the ring gear is produced by helically winding up a strip of teeth connected by tangential bridges, the teeth of the strip in the rectilinear state forming slots between one another that have convergent edges, the edges of the slots being substantially parallel to one another when the strip is wound up on itself to form the ring gear.

8. A rotary electric machine comprising a stator as claimed in claim 1 and a permanent magnet rotor.

9. A method for producing a stator, wherein the two following steps are implemented in succession: (i) disposing windings in the slots in a ring gear of the stator, and (ii) attaching a yoke to the ring gear of the stator.

10. The method as claimed in the claim 9, wherein, in step (i), at least one winding is disposed in two different, non-consecutive slots in the ring gear of the stator.

11. The method as claimed in claim 9, wherein the windings used in step (i) are obtained by prior deformation of shuttles having two parallel long sides and two semicircular ends.

12. The method as claimed in claim 9, wherein said deformation consists in spacing the two long sides of the shuttles perpendicularly apart from one another so as to obtain the windings.

13. A machine for manufacturing a stator for implementing the method as claimed in claim 9, comprising tools for simultaneously deforming several shuttles, so as to obtain the windings of a single stator.

14. The machine as claimed in claim 13, which is configured to allow the simultaneous fitting of several windings, on the ring gear.

Description

[0098] The invention may be understood better from reading the following detailed description of non-limiting exemplary embodiments thereof and from studying the appended drawing, in which:

[0099] FIG. 1 schematically and partially shows a cross section through a machine comprising a stator produced in accordance with the invention,

[0100] FIG. 1a schematically shows a metal strip intended to form a ring gear,

[0101] FIGS. 2a to 2c illustrate the disposition of the electrical conductors in the slots,

[0102] FIG. 3 is a schematic and partial view of a shuttle,

[0103] FIG. 4 is a view along the arrow IV in FIG. 3,

[0104] FIG. 5 is a perspective, schematic and partial view of a winding, and

[0105] FIG. 6 is a schematic and partial view illustrating the manufacture of the stator.

[0106] FIG. 1 illustrates a rotary electric machine 10 comprising a rotor 1 and a stator 2. The stator makes it possible to generate a rotary magnetic field for driving the rotor 1 in rotation, within the context of a synchronous motor, and in the case of an alternator, the rotation of the rotor induces an electromotive force in the windings of the stator.

[0107] Stator

[0108] The stator 2 comprises distributed windings 22, as illustrated, which are disposed in the slots 21 formed between the teeth 23 of a ring gear 25. The slots are closed in the direction of the air gap by tangential bridges 27 that connect two consecutive teeth of the ring gear 25 together. Moreover, the stator comprises a yoke 29 attached to the ring gear 25. The yoke 29 is equipped with semicircular longitudinal ribs 31 that are intended to accommodate ducts 13 for the circulation of a cooling liquid.

[0109] The windings 22 are disposed in a distributed manner in the slots 21 and have electrical conductors 28 that are disposed in an arranged manner in the slots 21.

[0110] The slots 21 have mutually parallel radial edges in the example described and have a hexagonal shape in cross section, being diamond-shaped. The electrical conductors in these slots have a circular cross-sectional shape. The arrangement of the latter is a hexagonal arrangement, as illustrated in FIG. 2a. The tangential bridges 27 have a width which is not constant but decreases and then increases. The filling rate is in this case more than 100%.

[0111] The ring gear 25 is produced by helically winding up a rectilinear strip of teeth connected by tangential bridges 27, as illustrated in FIG. 1a. The teeth 23 of the rectilinear strip form the slots 21 between one another which have converging edges, the edges of the slots being parallel to one another when the strip is wound up on itself to form the ring gear.

[0112] In one variant embodiment, the slots can have a rectangular cross-sectional shape, still with electrical conductors with a circular cross-sectional shape, as illustrated in FIG. 2b.

[0113] In yet another variant embodiment, the slots can have a rectangular cross-sectional shape, but with electrical conductors with a rectangular cross-sectional shape, as illustrated in FIG. 2c.

[0114] The stator 2 illustrated comprises more precisely 27 slots that are distributed in six poles, with a tooth pitch of . In other words, it comprises 1.5 slots per pole and per phase.

[0115] Each slot 21 comprises 18 electrical conductors in the example described, which are in this example enameled wires having a diameter of 1.32 mm. Filling is improved thereby and a better resulting torque is obtained. The conventional filling rate is in this case more than 94%. The term conventional filling rate means the ratio between the cumulative sum of the squares of the diameters of the conductors and the useful cross section of the slot.

[0116] Each slot comprises two stacked windings, and therefore two winding stages.

[0117] The thickness e of the yoke is relatively large compared with known machines, since the height of the slot has been able to be reduced by virtue of the increase in the filling rate.

[0118] Furthermore, the same goes for the width/of the teeth.

[0119] A significant reduction in the consumption of electrical field (or ampere-turns) at the stator, or a significant increase of the flux passing through the stator, may thus be obtained.

[0120] Rotor

[0121] The rotor 1 shown in FIG. 1 comprises a rotor magnetic mass 3 extending axially along the axis of rotation X of the rotor, this rotor mass being formed for example by a set of magnetic laminations stacked along the axis X, the laminations being for example identical and superposed exactly. They may be held together by clip-fastening, by rivets, by tie rods, welds or any other technique. The magnetic laminations are preferably made of magnetic steel. All grades of magnetic steel may be used.

[0122] The rotor mass 3 comprises a central opening 5 for mounting it on a shaft. The shaft may, in the example in question, be made of a non-magnetic material, for example of non-magnetic stainless steel or of aluminum, or else be magnetic.

[0123] The rotor 1 comprises a plurality of permanent magnets 7 disposed in housings 8 in the rotor magnetic mass 3. In the example described, the permanent magnets 7 are disposed in two rows 9a, 9b defining the six poles 11 of the rotor. Each of the rows 9a, 9b comprises two permanent magnets 7, which are disposed one on each side of a radial axis Y of said pole 11.

[0124] The permanent magnets 7 are both disposed in a common housing 8 that is formed in the rotor magnetic mass 3 and passed through by the radial axis Y of the pole. This housing 8 extends from the air gap in the direction of the shaft, and then back toward the air gap. The housings 8 are V-shaped or U-shaped.

[0125] The permanent magnets 7 are disposed in Vs oriented toward the air gap. For one and the same pole, a row of permanent magnets thus comprises two lateral branches. The Vs of one and the same pole are disposed concentrically; in other words, the Vs of one and the same pole are nested in one another. In the example described, a V has a shape that flares toward the air gap, the lateral branches of the V not being parallel to one another. None of the rows of a pole have a central magnet.

[0126] The permanent magnets 7 have a rectangular shape in cross section. They may be made of ferrite or, alternatively, of rare earths, for example of the neodymium type or the like. Preferably, the magnets are made of ferrite.

[0127] In the example illustrated in FIG. 1, the rotor comprises tangential bridges 16 formed between a housing 8 and the air gap. It does not have any material bridges other than tangential material bridges and in particular does not have radial bridges.

[0128] The rotor magnetic mass 3 comprises, for each pole, a pole piece 17 connected to the rest of the magnetic mass by tangential bridges 16 that are formed between each of the two ends of the housing and the outer surface of the rotor.

[0129] In one variant embodiment, the rotor magnetic mass 3 could comprise pole pieces 17 that are independent of the rest of the rotor magnetic mass.

[0130] In the example described, the polarity of the first pole of the rotor is defined by a first row 9a (or several first rows 9a) of inherent permanent magnets 7 and by a second row 9b of shared permanent magnets 7, said second row 9b likewise defining in part the polarity of the second pole of the rotor that is adjacent to the first pole. The shared permanent magnet 7 that contributes to the polarity of the first pole likewise contributes to the polarity of the second pole of the rotor that is adjacent to the first pole. The second row 9b of permanent magnets 7 thus simultaneously defines the polarities of each of the two consecutive poles of the rotor between which it is situated. The limit between the two consecutive poles passes through at least said shared permanent magnet 7.

[0131] In the example illustrated in FIG. 1, each of the poles of the rotor comprises a single first row. The first row of each of the poles is disposed in a V shape in these examples, the concavity of the row being oriented toward the apex of the pole, that is to say toward the air gap. It could of course be different, and the rotor could comprise for example two first rows, or more.

[0132] Stator Manufacturing Method and Machine

[0133] The stator is obtained by means of the manufacturing method which will now be described in detail.

[0134] In a preparatory step, shuttles 40 are manufactured by winding up electrical conductors in the form of an ancient stadium track, with bends that are as tight as possible, as illustrated in FIG. 3, so as to have two parallel long sides 41 and two semicircular ends 42.

[0135] Next, two rectilinear portions 43 of the two parallel long sides 41 of the shuttle 40 are spaced perpendicularly apart from one another, as illustrated in FIG. 4, said rectilinear portions 43 being intended to form the active portions of the final winding 22, that is to say to be inserted into the slots 21, the rest forming the coil heads 50. The winding thus obtained is illustrated in FIG. 5.

[0136] Finally, the two following steps are implemented in succession: [0137] (i) first of all, the windings 22 obtained from the shuttles 40 are disposed in the slots 21 in the ring gear 25 of the stator 2, and [0138] (ii) the yoke 29 is attached to the ring gear 25 of the stator 2.

[0139] In step (i), each winding 22 is disposed in two different, non-consecutive slots in the ring gear of the stator, so as to obtain a stator with distributed windings.

[0140] This method may be implemented by means of a machine for manufacturing a stator, comprising tools for simultaneously deforming several shuttles, or all the shuttles, so as to obtain the windings of a single stator.

[0141] The machine may be configured to allow the simultaneous fitting of several windings, or of all the windings, on the ring gear, as illustrated in FIG. 6.

[0142] The assembly obtained may be impregnated before being inserted into the annular yoke 29 also prepared.

[0143] Of course, the invention is not limited to the exemplary embodiments which have just been described.

[0144] The expression comprising a should be understood as being synonymous with comprising at least one.