WO2009068814A1

WO2009068814A1 - Rotary electric machine for automobile

Info

Publication number: WO2009068814A1
Application number: PCT/FR2008/052036
Authority: WO
Inventors: Eric Tora; Jacques Verot; Eric Vernay
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2007-11-13
Filing date: 2008-11-13
Publication date: 2009-06-04
Also published as: FR2923662B1; CN101855810A; FR2923662A1; BRPI0818263A8; BRPI0818263A2

Abstract

The invention relates to a rotary electric machine, in particular a starter for an automobile, that comprises a stator, a rotor (2) arranged so as to be capable of rotation in the stator about a longitudinal axis, at least one winding (8) including conducting segments (11), and a plurality of notches (40) formed on one of the stator and the rotor (2), extending substantially along the longitudinal axis and each having a bottom (41), wherein one at least of said notches (40) receives at least one conducting segment of the winding (8). Said at least one conducting segment (11) bears against the notch bottom (41) and has a crush deformation that is sufficient for maintaining the same in the notch (40) during a nominal operation of the rotary electric machine.

Description

Rotating electric machine for a motor vehicle

The invention relates to a rotating electrical machine, for example a starter for a motor vehicle, and a method of manufacturing such a machine.

Patent applications FR 2 708 398, FR 2 721 769 and FR 2 875 068 describe various processes for manufacturing starter rotor for a motor vehicle. These known methods include a step of crushing the son in notches of the rotor and / or a step of crimping the rotor to form teeth.

All these methods further include a step of impregnating the conductive son with a varnish to ensure the immobilization son in the notches by creating a bond between these son.

Impregnation of the rotor with a varnish can be problematic, especially because of the industrial facilities required, and the relatively long time of the operation.

In addition, the varnish may have the disadvantage of reducing the thermal exchange capacity of the rotor.

There is a need to overcome the aforementioned drawbacks.

The present invention thus relates to a rotating electrical machine, in particular a starter for a motor vehicle, comprising:

- a stator,

a rotor rotatably arranged in the stator about a longitudinal axis,

at least one winding comprising conductive segments,

a plurality of notches formed on one of the stator and the rotor extending substantially along the longitudinal axis, each having a bottom, at least one of the notches receiving at least one conductive segment of the winding, characterized in that said at least one conductive segment bears against the bottom of the notch and has a crush deformation which is sufficient to ensure its retention in the notch during normal operation of the rotating electrical machine.

Thanks to the invention, during the life of the electrical machine, the conductive segments can be held in the corresponding notches without additional means other than their crushing.

In particular, the electrical machine may advantageously be devoid of varnish deposited in contact with the conductive segments in the notches, after mounting the rotor in the stator.

The invention thus makes it possible to avoid impregnation operations of the rotor with a varnish, which simplifies the manufacture of the rotor, without altering the heat exchange capacities thereof.

In particular, the useful energy for the manufacture of the rotor can be reduced, which reduces the CO ₂ footprint of the rotor in accordance with a concern for the environment.

In an exemplary implementation of the invention, at least one of the notches receives at least two conductive segments, in particular aligned substantially along a radius of the rotor.

For example, each notch may receive four conductive segments aligned along a radius of the rotor.

Alternatively, at least two conductive segments in the same notch may be substantially aligned along a circumference of the rotor.

Preferably, each conductive segment has an elongated cross section along a circumference of the rotor, this shape being conferred during the crushing of the conductive segment.

In an exemplary implementation of the invention, each conductive segment may have, before crush deformation, a circular cross section, or oval. This circular cross section is found on winding buns. The winding is for example formed by one or more son.

Alternatively, each conductive segment may have, before crushing, a polygonal cross section, including rectangular or square.

The ratio between the thickness of this segment after crushing and the thickness before crushing is called the "crush rate" of a conductive segment.

The ratio of the thickness of this conductive segment to its width is called the "aspect ratio" of a conductive segment.

At least one of the conducting segments, in particular all the conductive segments in the notches, advantageously has a crushing ratio in the range [0.6; 1, especially in the range [0.7; 0.9], especially in the range [0.75; 0.85].

Preferably, at least one of the conductive segments, especially all conductive segments in the notches, has a form ratio in the range [0.66; 1, especially in the range [0.68; 0.84], especially in the range [0.7; 0.75].

In particular, the aspect ratio may be substantially equal to 0.71.

In an exemplary implementation of the invention, the slots may each comprise a longitudinal opening opposite the bottom, and at least one of the notches may comprise a free space extending between the conductive segment closest to the opening of the notch and the opening itself, this free space being provided during the crushing of the segment (s) conductor (s) in the notch.

Preferably, the depth of the free space is in the range [0.1 mm; 2mm].

If desired, the depth of the free space of the notch is substantially zero.

Advantageously, at least one of the notches, in particular all the notches, has a filling ratio, defined as the ratio between the section occupied by the conductive segments in a notch and the section of the empty notch, in the range [60%; 98%], especially in the interval [70%; 95%], especially in the meantime [75%; 92%].

In an exemplary implementation of the invention, the notches may be formed on a body, in particular a rotor body, and the body may comprise at least one tooth projecting from one of the notches, this tooth making it possible to maintain the conductive segments in place in the notch.

In particular, the tooth may extend at least partially in the free space of the notch.

The rotor body may have a longitudinal groove extending above the tooth, this groove being initially provided to facilitate the deformation of the rotor body to form this tooth.

The bottom of each notch may have in cross section a concave concave shape directed towards the inside of the notch, this shape being substantially complementary to that of the conductive segments.

In an exemplary implementation of the invention, at least one of the notches may comprise two substantially plane longitudinal walls facing each other.

In a variant, at least one of the notches may have two longitudinal walls facing each other, these walls having recessed and raised shapes, in particular making it possible to improve the retention of the conductive segments in the notch.

The electrical machine may comprise at least one insulating sheet interposed between at least one conductive segment and a wall of the notch.

The invention also relates to a method of manufacturing a rotary electrical machine as defined above, the method comprising the following steps: a / insert at least one conductive segment in each notch, and b / apply a force of sufficient crushing on this conductive segment to give it a deformation allowing it to remain in the notch during normal operation of the rotating electrical machine. The method may further comprise the following step: c / crimping the rotor body locally to form on this body one or more teeth projecting into the notch. Where appropriate, steps b / and c / may be concurrent. Alternatively, step b / precedes step c /.

The crushing force may be variable over a length of at least one of the conductive segments.

Preferably, the crushing force is greater on a central zone of the conductive segment than on peripheral zones of the conductive segment.

Thus, the central zone of the conductive segment in the notch may present a greater deformation than that of the peripheral zones of the conductive segment.

The invention will be better understood on reading the following detailed description, non-limiting examples of implementation of the invention, and on examining the appended drawing, in which:

FIG. 1 represents, schematically and partially, a rotating electrical machine according to one embodiment of the invention,

FIG. 2 represents, schematically and partially, in an isolated manner, the rotor of the machine of FIG. 1,

FIG. 3 is a diagrammatic and partially cross-sectional view along III - III of the rotor of FIG. 2,

FIG. 4 is a diagrammatic and partial cross-section of a conductive segment of the machine of FIG. 1, before crushing,

FIG. 5 represents, schematically and partially, in cross-section along the V-V rotor of FIG. 2, FIG. 6 is a diagrammatic and partial cross-sectional view of a rotor of an electric machine according to another embodiment of the invention;

FIG. 7 is a diagrammatic and partial cross-sectional representation of a rotor of an electric machine according to another embodiment of the invention, and

- Figures 8 and 9 show, schematically and partially, crash punches according to two examples of implementation of the invention.

There is shown in Figure 1 a rotating electric machine forming a starter 1 of a motor vehicle.

This starter 1 comprises, firstly, a rotor 2, also called armature, rotatable about a longitudinal axis X, and secondly, a stator 3, also called inductor, around the rotor 2.

The starter 1 has an electric power of 1 kW.

The stator 3 comprises a yoke 4 carrying a plurality of permanent magnets 5.

The rotor 2 comprises a rotor body 7 arranged in line with the magnets 5 of the stator 3, and a winding 8 wound in notches of the rotor body 7.

The starter 1 may be of the type six magnet poles for example.

In a variant, the stator may comprise a winding instead of the magnets.

The winding 8 comprises a plurality of conductive wires forming, on either side of the rotor body 7, a front bun 9 and a rear bun 10.

The rotor 2 is provided at the rear with a collector 12 comprising a plurality of contact pieces electrically connected to the winding 8.

A group of brushes 13 and 14 is provided for the electrical supply of the winding 8, one of the brushes 13 being connected to the ground of the device 1 and another of the brushes 14 being connected to an electrical terminal 15 of a switch 17 via a wire 16. The brushes are for example four in number.

The brushes 13 and 14 rub on the collector 12 when the rotor 2 is rotating. The starter 1 further comprises a launcher assembly 19 slidably mounted on a drive shaft 18 and drivable in rotation about the X axis by the rotor 2.

A gear reduction unit 20 is interposed between the rotor 2 and the drive shaft 18, in a manner known per se.

The launcher assembly 19 comprises a drive element formed by a pulley 21 and intended to engage on a drive member of the combustion engine, not shown. This drive member is for example a belt.

The pulley 21 may be replaced by a gear element, in particular a gear wheel, for driving the combustion engine.

The launcher assembly 19 further comprises a freewheel 22 and a pulley washer 23 defining between them a groove 24 for receiving the end 25 of a fork 27.

This fork 27 is actuated by the switch 17 to move the launcher assembly 19 relative to the drive shaft 18, along the axis X, in a manner known per se.

The switch 17 comprises, in addition to the terminal 15 connected to the brush 14, a terminal 29 connected via an electrical connection element, in particular a wire 30, to a power supply of the vehicle, in particular a battery, not shown.

We will now describe with reference to Figures 2 to 5 the rotor 2 in more detail.

As illustrated in FIG. 3, the body of the rotor 7 comprises a plurality of notches 40 extending along the X axis, each notch 40 having a bottom 41, two longitudinal walls 42 and 43 that are substantially planar facing one another and a longitudinal opening. 44 opposite to the merits 41.

The bottom 41 of each notch 40 has in cross section a concave concave shape directed towards the inside of the notch 40. Each notch 40 further comprises at least one insulating sheet 34 interposed between the conductive segments 1 1 inserted in the notch 40 and the walls 42 and 43.

This insulating sheet 34 extends, on the one hand, along the walls 42 and 43 and on the bottom 41, and, on the other hand, on an outer periphery 28 of the rotor body 7.

In the example described, each notch 40 receives four conductive segments 1 1 of the coil 8 aligned substantially along a radius of the rotor 2.

The conductive segments 1 1 are formed by wire portions of the winding 8, which son include a conductive core 31 and an insulating sheath 32, for example enamel.

The conductive segments 1 1 are put in place in the corresponding slots 40 in the following manner.

These conductive segments 1 1, initially formed by portions of son of circular cross section, as illustrated in FIG. 4, are placed in the corresponding slots 40.

Then using a tool 50 provided with a central punch 51, it is proceeded to the crushing of the conductive segments 1 1 in each of the notches 40, as can be seen in Figure 5.

The central punch 51 is arranged to occupy the entire length of the notch 40 when introduced into it.

The crushing force is chosen so that the deformation undergone by the conducting segments 1 1 in the corresponding notch 40 is sufficient to keep them in place during normal operation of the electric machine.

The tool 50 further comprises lateral punches 52 to generate, during the crushing of the conductive segments 1 1, a deformation of the rotor body 7 to locally create teeth 46, in each notch 40, which come into bearing on the most radially outer conductor segment 1 1.

In the example described, the lateral punches 52 are connected to the central punch 51.

Alternatively, the lateral punches 52 can be arranged to slide relative to the central punch 51. These teeth 46 ensure a reinforced holding of the conducting segments 1 1 in the corresponding notch 40.

In order to facilitate formation of the teeth 46 during crimping with the aid of lateral punches 52, the rotor body 7 is initially provided with longitudinal grooves 47 creating zones of preferential deformation.

These grooves 47 are present after crimping and located immediately above the teeth 47.

As illustrated in FIGS. 2 and 3, the rotor 2 is devoid of varnish deposited in contact with the conductive segments 1 1 in the notches 40, after assembly of the rotor 2 in the stator 3.

The process does not require the impregnation of the conductive segments with a varnish.

As illustrated in FIGS. 3 and 5, each conducting segment 1 1 has, after crushing, an elongated cross-section along a circumference of the rotor 2.

Note "e" the thickness of a conductive segment 1 1 measured along a radial axis Y and "I" its width measured along a Z axis perpendicular to the Y axis, the Y and Z axes being contained in a perpendicular plane to the X axis.

The aspect ratio (e / 1) is defined as the ratio between the thickness e and the width I of a conductive segment 1 1.

In the example described, the conductive segments 1 1 inserted in the notches 40 have a shape ratio substantially equal to 0.7.

As illustrated in FIG. 4, each conductive segment 1 1 has, before crushing, a circular section defining an initial thickness which is noted "e ₀ ".

The ratio between the thickness e of a conductive segment 1 1, after its crushing, and its initial thickness e ₀ , defines a crushing ratio (e / e ₀ ) of this conductive segment 11.

In the example described, the conducting segments 1 1 inserted in the notches 40 have a crush rate in a range [0.75; 0.9]. Each notch 40 has a free space 45 extending between the conductive segment 1 1 closest to the opening of the notch 44 and the opening 44 itself, the free space 45 having a depth p measured according to the Y axis.

The depth p is chosen substantially equal to 1, 6mm.

Each notch 40 has a fill ratio, defined as the ratio between the section occupied by the conductive segments 11 in a notch 40 and the section of the notch 40 empty, in a range [65%, 80%].

In the exemplary implementation of the invention, the rotor of the electric machine has the following characteristics:

- initial thickness of a conductive segment e ₀ = 2mm;

- thickness of a conductive segment after crushing e = 1, 57mm;

- width of a conductive segment after crushing I = 2.26mm;

- aspect ratio = 0.69;

- crush rate = 0.78;

- depth of the free space of the notch = 1, 57mm;

- fill rate = 76%.

Of course, the invention is not limited to the implementation example which has just been described.

For example, in an alternative embodiment of the rotor according to the invention illustrated in FIG. 6, each free space 45a of the rotor 2a has a very small depth, substantially equal to 0.4 mm, and the filling ratio is in a range [80%; 98%].

For example again, FIG. 7 illustrates an embodiment variant of the rotor according to the invention, in which this rotor 2b comprises notches 40b comprising two longitudinal walls 42b and 43b facing each other, these walls 42b and 43b having recessed shapes 48b and in reliefs 49b.

These recessed shapes 48b and reliefs 49b make it possible to receive the conductive segments 11 with reinforced retention of these conductive segments 11 in the notches 40b. In the example described with reference to FIG. 5, the punch 51 for crushing the conductive segments 11 may have a straight leading edge at least along the entire length of the notch 40.

Alternatively, as can be seen in Figure 8, the punch 51 may include a straight edge 51 1 extended on either side by withdrawals 512.

These withdrawals 512 have a curved concavity shape directed towards the conductive segment 11.

When the punch 51 crushes the conductive segments 1 1, the right edge 511 is applied to a central zone of the conductive segment 1 1 and causes the crushing of this central zone.

At the same time, the withdrawals 512 gradually apply to the peripheral zones of the driver segment 1 1 and crush them with less effort.

A variable crushing force is thus applied by the punch 51.

In the exemplary embodiment of the invention illustrated in FIG. 9, the punch 51 comprises a central punching element 513 and, on either side thereof, two peripheral punching elements 514.

These punch elements 513 and 514 each have a straight edge and are independent of each other.

When the punch 51 crushes one of the conductive segments 1 1, the leading edge of the central punch element 513 is applied to the central zone of the conductive segment 1 1 in the notch 40 following a stroke C ₂ .

The peripheral punch elements 514 are moved over a stroke C ₃ smaller than the stroke C ₂ of the central punch element 513 so that the conductive segment 1 1 is more crushed in a central zone than in axially peripheral zones.

Claims

claims

1. Rotating electrical machine (1), in particular a starter for a motor vehicle, comprising:

a stator (3),

a rotor (2, 2a) arranged rotatably in the stator (3) about a longitudinal axis (X),

at least one winding (8) comprising conductive segments

(1 1),

a plurality of notches (40) formed on one of the stator (3) and the rotor (2, 2a) extending substantially along the longitudinal axis (X), each having a bottom (41), at least one of the notches (40) receiving at least one conductive segment of the coil (11), characterized in that the at least one conductive segment (1 1) bears against the bottom of the notch (41) and presents a crush deformation which is sufficient to ensure its retention in the notch (40) during normal operation of the rotating electrical machine (1).

2. Machine (1) according to the preceding claim, characterized in that it is devoid of varnish deposited in contact with the conductive segments (1 1) in the notches (40), after mounting the rotor (2, 2a) in the stator (3).

3. Machine (1) according to one of claims 1 or 2, characterized in that at least one of the notches (40) receives at least two conductive segments (1 1), in particular aligned substantially along a radius of the rotor (2, 2a).

4. Machine (1) according to any one of the preceding claims, characterized in that each conductive segment (1 1) has an elongated cross section along a circumference of the rotor (2, 2a).

5. Machine (1) according to any one of the preceding claims, characterized in that at least one of the conductive segments (11), including all conductive segments (11) in the notches (40), has (nt ) a crush rate in the range [0.6; 1, especially in the range [0.7; 0.9], especially in the range [0.75; 0.85].

6. Machine (1) according to any one of the preceding claims, characterized in that at least one of the conductive segments (11), in particular all conductive segments (11) in the notches (40), has (nt ) a form ratio in the range [0.66; 1, especially in the range [0.68; 0.84], especially in the range [0.70; 0,75].

7. Machine (1) according to any one of the preceding claims, the notches (40) each having a longitudinal opening (44) opposite the bottom (41), characterized in that at least one of the notches (40) has a free space (45, 45a, 45b) extending between the conductive segment (11) nearest the opening of the notch (44) and the opening (44) itself.

8. Machine (1) according to any one of the preceding claims, characterized in that at least one of the notches (40), including all the notches (40), has (s) a filling rate included in the interval [60% m; 98%], especially in the interval [70%; 95%], especially in the meantime [75%; 92%].

9. Machine (1) according to one of claims 7 and 8, characterized in that the depth of the free space (45, 45a, 45b) is substantially zero.

10. Machine (1) according to any one of the preceding claims, characterized in that the notches (40) are formed on a body (7), in particular a rotor body (2, 2a), and by the fact that the body (14) has at least one tooth (46) projecting into one of the notches (40).

1 1. Machine (1) according to any one of the preceding claims, characterized in that the body (7) has a longitudinal groove (47) extending above the tooth (46).

12. Machine (1) according to any one of the preceding claims, characterized in that at least one of the notches (40) comprises two substantially plane longitudinal walls facing (42, 43).

13. Machine (1) according to any one of claims 1 to 11, characterized in that at least one of the notches (40) comprises two longitudinal walls facing (42b, 43b), these walls having shapes in shape. hollow (48b) and raised (49b).

14. A method of manufacturing a rotary electric machine (1) according to claim 1, comprising the following steps: a / insert at least one conductive segment (1 1) in each notch

(40), and b / apply sufficient crushing force on this conductive segment

(1 1) to give it a deformation allowing its maintenance in the notch (40) during normal operation of the rotating electrical machine (1).

15. Method according to the preceding claim, further comprising the following step: c / crimping locally the rotor body (7) to form on this body (7) one or more teeth (46) projecting into the notch ( 40), in particular by means of a punch (52).

16. The method of claims 14 and 15, characterized in that the steps b / and c / are concomitant.

17. Method according to any one of claims 14 to 16, characterized in that the crushing force is variable along the length of the conductive segment (1 1) in the notch (40).