FR2923662A1 - ROTATING ELECTRIC MACHINE FOR MOTOR VEHICLE. - Google Patents

Abstract

The invention relates to a rotary electrical machine, in particular a starter for a motor vehicle, comprising a stator, a rotor (2) rotatably arranged in the stator about a longitudinal axis, at least one winding (8) comprising conductive segments (11), and a plurality of notches (40) formed on one of the stator and the rotor (2) extending substantially along the longitudinal axis, each having a bottom (41), one less notches (40) receiving at least one conductive segment of the coil (8). Said at least one conductive segment (11) bears against the bottom of the notch (41) and has a crush deformation which is sufficient to ensure its retention in the notch (40) during normal operation of the rotating electric machine.

Description

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 CO2 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, in particular 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 notches 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 / have a filling ratio, defined as the ratio between the section occupied by the conductive segments in a notch and the section of the vacuum notch, included in the meantime [60%; 98%], especially in the interval [70%; 95%], especially in the meantime [75%; 92%].

In an exemplary embodiment 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 protruding into the notch, in particular with the aid of a punch. Where appropriate, steps b / and c / may be concurrent.

Alternatively, step b / precedes step c /. The invention will be better understood on reading the following detailed description of examples of non-limiting embodiments of the invention, and on examining the appended drawing, in which: FIG. schematically and partially, a rotary electrical machine according to an embodiment of the invention, - Figure 2 shows, schematically and partially, in isolation, the rotor of the machine of Figure 1, -le figure 3 shows, schematically and partially, in cross-section along III-III, the rotor of FIG. 2; FIG. 4 is a schematic and partially cross-sectional view of a conductive segment of the machine of FIG. 1, before crushing, FIG. represents, schematically and partially, in cross-section along V - V, the rotor of FIG. 2; - FIG. 6 represents, schematically and partially, in cross section, a rotor of an electric machine. e according to another example of implementation of the invention, and - Figure 7 shows, schematically and partially in cross section, a rotor of an electric machine according to yet another example 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. 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 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 driving 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 The bottom 41 of each notch 40 has in cross section a concave concave shape directed towards the interior of the notch 40. Each notch 40 further comprises at least one insulating sheet 34 interposed between the conductive segments. 11 inserts into 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 a periphery In the example described, each notch 40 receives four conductive segments 11 of the coil 8 substantially aligned along a radius of the rotor 2.

The conductive segments 11 are formed by wire portions of the winding 8, which son comprise a conductive core 31 and an insulating sheath 32, for example enamel. The conductive segments 11 are put in place in the corresponding notches 40 in the following manner.

These conductive segments 11, initially formed by wire portions of circular cross-section, as illustrated in FIG. 4, are placed in the corresponding notches 40. Then with the aid of a tool 50 provided with a central punch 51, the conductive segments 11 are crushed in each of the notches 40, as can be seen in FIG. 5. The central punch 51 is arranged to occupy the entire length of the notch 40 when it is introduced into it. The crushing force is chosen so that the deformation experienced by the conductive segments 11 in the corresponding notch 40 is sufficient to hold them in place during normal operation of the electric machine. The tool 50 further comprises lateral punches 52 in order to generate, during the crushing of the conductive segments 11, a deformation of the rotor body 7 in order locally to create teeth 46, in each notch 40, which come 15 bearing on the most radially outer conductive segment 11. In the example described, the lateral punches 52 are connected to the central punch 51. In a variant, the lateral punches 52 can be arranged to slide relative to the central punch 51. These teeth 46 ensure a reinforced holding of the conductive segments 11 20 in the corresponding notch 40. In order to facilitate the formation of the teeth 46 during crimping with the aid of the 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 Figures 2 and 3, the rotor 2 is free of varnish deposited in contact with the conductive segments 11 in the notches 40, after mounting the rotor 2 in the stator 3. The method does not require the impregnation of the conductive segments with a varnish.

As illustrated in FIGS. 3 and 5, each conductive segment 11 has, after crushing, an elongated cross-section along a circumference of the rotor 2.

Note "e" the thickness of a conductive segment 11 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 plane perpendicular to the X axis.

The shape ratio (el) is defined as the ratio between the thickness e and the width I of a conductive segment 11.

In the example described, the conductive segments 11 inserted in the notches 40 have a shape ratio substantially equal to 0.7.

As illustrated in FIG. 4, each conductive segment 11 has, before crushing, a circular section defining an initial thickness which is recorded as 0. The ratio between the thickness e of a conducting segment 11, after its crushing, and its initial thickness eo, defines a crushing rate (e / eo) of this conductive segment 11.

In the example described, the conductive segments 11 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 segment

20 conductor 11 closest to the opening of the notch 44 and the opening 44 itself, the free space 45 having a depth p measured along the Y axis.

The depth p is chosen substantially equal to 1.6 mm.

Each notch 40 has a filling 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 eo = 2mm;

- thickness of a conductive segment after crushing e = 1.57mm; 30-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.

Claims (17)

claims 1. A rotary electric machine (1), in particular a starter for a motor vehicle, comprising: a stator (3), a rotor (2, 2a) rotatably arranged in the stator (3) about a longitudinal axis ( X), at least one winding (8) comprising conductive segments (11), 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 winding (11), characterized in that the at least one conductive segment (11) ) is in abutment against the bottom of the notch (41) and has 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 (11) 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 (11), 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 (11) 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 claim 7, characterized in that the depth of the free space (45, 45a, 45b) is substantially zero. 20 25 9. 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 fill rate included in the interval [60%; 98%], especially in the interval [70%; 95%], especially in the meantime [75%; 92%]. 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). 11. Machine (1) according to the preceding claim, 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.Machine (1) according to any one of the preceding claims, characterized in that it comprises at least one insulating sheet (34) interposed between at least one conductive segment (11) and a wall of the notch (42). , 42b, 43, 43b). 30 15. A method of manufacturing a rotary electric machine (1) according to claim 1, comprising the following steps: a / insert at least one conductive segment (11) in each notch (40), and b / apply a force of sufficient crushing on this conductive segment (11) to give it a deformation to maintain it in the notch (40) during normal operation of the rotating electrical machine (1). 16. Method according to the preceding claim, further comprising the following step: cl crimping the rotor body (7) locally to form on this body (7) one or more teeth (46) projecting into the notch (40). ), in particular using a punch (42). 17. The method of claims 15 and 16, characterized in that the steps b / and cl are concomitant.