FR3054743A1 - COIL FOR ROTATING ELECTRICAL MACHINE - Google Patents

Abstract

The invention relates mainly to a coil (31) for a rotary electrical machine comprising: - a winding (50) comprising a plurality of turns (51) made from a thermosetting wire (52), - said winding (50) being coated with an elastic layer (55) having an electrical insulator function.

Description

Holder (s): VALEO ELECTRIC EQUIPEMENTS MOTOR Simplified joint-stock company.

Extension request (s)

Agent (s): VALEO EQUIPEMENTS ELECTRIQUES MOTOR Simplified joint-stock company.

COIL FOR ROTATING ELECTRIC MACHINE.

(6 /) The invention relates mainly to a coil (31) for a rotary electrical machine comprising:

a winding (50) comprising a plurality of turns (51) formed from a thermosetting wire (52),

- Said winding (50) being coated with an elastic layer (55) having an electrical insulating function.

FR 3 054 743 - A1

COIL FOR ROTATING ELECTRIC MACHINE

The present invention relates to a coil for a rotating electrical machine. The invention finds a particularly advantageous, but not exclusive, application in the field of alternators for motor vehicles. Such an alternator transforms mechanical energy into electrical energy and can be reversible.

Such a reversible alternator is called an alternator-starter and makes it possible to transform electrical energy into mechanical energy in particular for starting the heat engine of the vehicle. The invention can also be implemented with an electric motor.

In a manner known per se, an alternator comprises a casing and, inside thereof, a claw rotor, integral in rotation with a shaft, and a stator which surrounds the rotor with the presence of an air gap.

The stator comprises a body constituted by a stack of thin sheets 15 forming a crown, the inner face of which is provided with notches open towards the inside to receive phase windings. These windings pass through the notches in the stator body and form buns protruding from either side of the stator body. The phase windings are obtained for example from a continuous wire covered with enamel or from conductive elements in the form of pins connected together by welding. These windings are polyphase windings whose ends are connected to an electronic power module comprising in particular a rectifier bridge.

Furthermore, the rotor comprises two pole wheels each having a transverse orientation flange provided at its outer periphery with claws of axial orientation. The claws of the pole wheels are nested relative to each other. A cylindrical core is interposed axially between the flanges of the wheels. This core carries at its outer periphery an excitation coil formed around an insulating element radially interposed between the core and the coil. A varnish deposited during a impregnation step of the rotor ensures mechanical maintenance of the coil.

The conventional configuration of the rotor requires providing a large clearance between the flanges and the axial ends of the coil to avoid deformation of the coil during assembly and to compensate for the dimensional variability of the coil insulation. We also observe crossings of son during winding increasing the size of the coil. In addition, the current coil is slightly cooled by convection due to the vacuum existing between the front and rear flanges of the rotor.

The invention aims to effectively remedy these drawbacks by proposing a coil for a rotating electric machine comprising:

- a winding comprising a plurality of turns formed from a thermosetting wire,

- Said winding being coated with an elastic layer having an electrical insulating function.

The invention thus makes it possible to ensure electrical insulation of the coils while overcoming the dimensional variability of the coil insulation usually used. By controlling the space occupied by the coil, the invention allows a reduction in the axial play between the coil and the pole wheels. The invention also makes it possible to improve the vibration resistance of the coil and is of economic interest, insofar as it is possible to omit the step of impregnating varnish.

According to one embodiment, said elastic layer is made of a silicone-based material. The use of a silicone-based material allows the heat generated by the coil to be evacuated by conduction and therefore to better control its temperature during the operation of the alternator. Due to better cooling of the coil, its magnetic performance of flux generation is improved.

According to one embodiment, said elastic layer is loaded with additives promoting thermal dissipation.

According to one embodiment, said thermosetting wire comprises a conductive core covered with a first layer of enamel ensuring electrical insulation, a second layer of enamel joining two adjacent turns of said winding, and an intermediate bonding layer ensuring mechanical connection between said first layer of enamel and said second layer of enamel.

Due to the connection between the turns, the winding obtained has rows of regular turns in which the wire crossings are avoided as much as possible. This improves the filling rate of the rotor in active material.

According to one embodiment, said thermosetting wire comprises a conductive core made of copper or aluminum.

According to one embodiment, said winding is mounted between two holding flanges. The retaining flanges ensure the centering of the coil relative to the injection mold and relative to the pole wheels during assembly of the rotor.

According to one embodiment, each retaining flange comprises a centering collar cooperating with an internal periphery of said winding.

According to one embodiment, each retaining flange comprises feet extending axially in the opposite direction of said winding, each foot being intended to engage in an entry space of an active element of said rotary electric machine.

According to one embodiment, each retaining flange has a plurality of through holes, an axis of each through hole being parallel to an axis of revolution of said winding.

The invention also relates to a rotary electric machine characterized in that it comprises a coil as defined above.

According to one embodiment, said rotary electrical machine comprises a rotor comprising two pole wheels, said coil being mounted wedged, without play, between said two pole wheels.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given only by way of illustration but in no way limit the invention.

Figure 1 is a longitudinal sectional view of an alternator according to the present invention;

Figure 2 shows a perspective view of a coil according to the present invention;

Figure 3 is a partial longitudinal sectional view of the coil according to the present invention;

Figure 4 is a cross-sectional view of a spool yarn according to the present invention;

Figures 5a and 5b are respectively perspective and side views of a flange holding the coil according to the present invention.

Identical, similar, or similar elements retain the same reference from one figure to another.

FIG. 1 shows a compact, multi-phase alternator 10, in particular for a motor vehicle. The alternator 10 is able to transform mechanical energy into electrical energy and may be reversible. Such a reversible alternator, called an alternator-starter, makes it possible to transform electrical energy into mechanical energy in particular for starting the heat engine of the vehicle.

This alternator 10 comprises a casing 11 and, inside thereof, a claw rotor 12 mounted on a shaft 13, and a stator 16, which surrounds the rotor 12 with the presence of an air gap between the outer periphery of the rotor 12 and the internal periphery of the stator 16. The axis X along which the shaft 13 extends forms the axis of rotation of the rotor 12.

The casing 11 has front 17 and rear 18 bearings carrying the stator 16. The bearings 17, 18 are hollow in shape and each carry a ball bearing centrally for the rotational mounting of the shaft 13.

More specifically, the rotor 12 comprises two pole wheels 24, 25 each having a flange 28 of transverse orientation provided at its outer periphery with claws 29 for example of trapezoidal shape and axial orientation. The claws 29 of one wheel 24, 25 are directed axially towards the flange 28 of the other wheel. The claws 29 of a pole wheel 24, 25 penetrate into an intermediate space existing between two claws 29 adjacent to the other pole wheel, so that the claws 29 of the pole wheels 24, 25 are nested with respect to the other.

A cylindrical core 30 is axially interposed between the flanges 28 of the wheels 24, 25. In this case, the core 30 consists of two half-cores each belonging to one of the flanges 28. This core 30 carries a coil at its outer periphery excitation 31 described in more detail below.

The shaft 13 may be force-fitted into the central bore of the pole wheels 24, 25. On the side of its front end, the shaft 13 may include a threaded part for fixing a pulley 35. The pulley 35 belongs to a movement transmission device with at least one belt between the alternator 10 and the engine of the motor vehicle.

The rear bearing 18 carries a brush holder 38 provided with brushes 39 intended to rub against rings 40 of a collector 41 to supply the winding of the rotor 12.

Furthermore, the stator 16 comprises a body 43 in the form of a pack of sheets provided with notches equipped with insulating notches for mounting the phases of the stator 16. Each phase comprises at least one phase winding passing through the notches of the stator body 43 and forms, with all the phases, a front bun 46 and a rear bun 47 on either side of the stator body 43.

The phase windings are obtained for example from a continuous wire covered with enamel or from conductive elements in the form of pins electrically connected to each other for example by welding. The phase windings are electrically connected to an electronic power module. This module notably comprises a rectifier bridge constituted for example by diodes or transistors of the MOSFET type.

As illustrated by FIGS. 2 and 3, the excitation coil 31 of the rotor comprises a winding 50 having a plurality of turns 51 formed from a thermosetting wire 52. The wire 52 used to make the winding 50 is preferably a single and continuous wire. The winding 50 is further coated with an elastic layer 55 having in particular an electrical insulating function.

Advantageously, the elastic layer 55 is made of a silicone-based material in order to dissipate the heat generated by the coil 31 by conduction. Due to better cooling of the coil 31, its magnetic performance of flux generation is improved . If necessary, the elastic layer 55 is loaded with additives promoting heat dissipation. The elastic coating layer 55 covers the entire volume of the winding 50 of generally annular shape having an axis of revolution Y. This volume is delimited by the axial end faces 58, 59, as well as the internal cylindrical peripheries 60 and external 61 of the winding 50. The coating layer 55 can be produced by injecting a silicone-based material into a corresponding mold. The winding 50 of the coil 31 is thus entirely embedded in the silicone material.

As illustrated in FIG. 4, the thermosetting wire 52 comprises a conductive core 64 preferably made of copper. Alternatively, the conductive core 64 may be made of aluminum. The conductive core 64 is covered with a first layer of enamel 65 providing electrical insulation, a second layer of enamel 66 joining two adjacent turns 51 of the winding 50, and an intermediate connecting layer 67 ensuring a mechanical connection between the first enamel layer 65 and the second enamel layer 66. The wire 52 shown has a round section. As a variant, the wire 52 may have a section of square shape, in the form of a flat, or any other shape adapted to the application. The wire 52 may also take the form of an elongated strip of rectangular shape wound on itself around an axis.

The connection between the adjacent turns 51 of the coil 31 is obtained by passing a current of high intensity through the wire 52 after the winding 50 has been produced on a support. This has the effect of heating the second layer of enamel 66 which will polymerize while cooling to ensure the connection between the turns 51. Due to the connection between the turns 51, the coil 31 obtained has rows of regular turns 51 in which the wire crossings 52 are avoided as much as possible. This improves the filling rate of the rotor 12 in active material.

Preferably, the silicone coated coil 31 is mounted between two retaining flanges 70. As illustrated in FIGS. 5a and 5b, each retaining flange 70 of axis Z has a wall 71 in the form of an annular crown. The axis Z is substantially coincident with the axis Y of the winding when the retaining flange 70 is pressed against the winding 50.

A centering collar 72 has an annular shape with axial orientation. This collar 72 comes from an internal periphery of the crown 71. The collar 72 is intended to be inserted into the internal opening 75 of the winding 50 so as to cooperate with the internal periphery 60 of the winding 50. The collar 72 has for this purpose an external diameter substantially equal to the diameter of the internal opening 75 of the winding 50.

In addition, each retaining flange 70 advantageously comprises feet 78 extending axially in the opposite direction from the winding 50. Each foot 78 is intended to engage in an entry space of a corresponding pole wheel 24, 25 .

The feet 78 ensure the centering of the coil 31 relative to the pole wheels 24, 25 during the mounting of the rotor 12. This guarantees correct positioning of the ends 81, 82 of the coil 31 for establishing connections with the collector 41. These feet 78 may also be used to center the coil 31 relative to the silicone resin injection mold.

Each retaining flange 70 preferably comprises a plurality of through orifices 83. The axis of each orifice 83 is parallel to the axis of revolution Y of the winding 50. These orifices 83 allow the penetration of the silicone layer 55 , which improves the rotational resistance of the coil 31.

In order to increase the filling rate of the rotor 12 or in isoperformance to reduce its size, the coil 31 is mounted wedged, without play, between the two pole wheels 24, 25. Thanks to the layer of silicone 55, the coil 31 will stress during the packaging of the rotor 12 thus avoiding any possible vibration during the operation of the alternator.

If the coil 31 has been described with reference to its use with a rotor 12 of a rotating electrical machine, such a coil 31 may also be used with the stator 16 of the electrical machine, for example for producing a winding of the type concentric in which preformed coils are mounted around each tooth of stator 16.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention from which one would not depart by replacing the various elements with any other equivalent.

In addition, the various features, variants, and / or embodiments of the present invention can be combined with one another in various combinations, insofar as they are not incompatible or mutually exclusive of one another.

Claims (11)

1. Coil (31) for a rotating electric machine (10) comprising: a winding (50) comprising a plurality of turns (51) formed from a thermosetting wire (52), 5 - said winding (50) being coated with an elastic layer (55) having an electrical insulating function. 2. Coil according to claim 1, characterized in that said elastic layer (55) is made of a silicone-based material. 3. Coil according to claim 1 or 2, characterized in that said elastic layer io (55) is loaded with additives promoting thermal dissipation. 4. Coil according to any one of claims 1 to 3, characterized in that said thermosetting wire (52) comprises a conductive core (64) covered with a first layer of enamel (65) ensuring a 15 electrical insulation, a second layer of enamel (66) joining two turns (51) adjacent to said winding (50), and an intermediate bonding layer (67) ensuring a mechanical connection between said first layer of enamel (65) and said second layer of enamel (66). 5. Coil according to claim 4, characterized in that said wire 20 thermosetting (52) comprises a conductive core (64) made of copper or aluminum. 6. Coil according to any one of claims 1 to 5, characterized in that said winding (50) is mounted between two holding flanges (70). 25 7. Coil according to claim 6, characterized in that each retaining flange (70) comprises a centering flange (72) cooperating with an internal periphery (60) of said winding (50). 8. Coil according to claim 6 or 7, characterized in that each retaining flange (70) comprises feet (78) extending axially in the opposite direction of said winding (50), each foot (78) being intended to s' engaging in an entry space of an active element of said rotary electrical machine (10). 9. Coil according to any one of claims 6 to 8, 5 characterized in that each retaining flange (70) comprises a plurality of through holes (83), an axis of each through hole (83) being parallel to a axis of revolution (Y) of said winding (50). 10. Rotating electric machine (10) characterized in that it comprises a coil (31) as defined according to any one of the preceding claims. 11. A rotary electrical machine according to claim 10, characterized in that it comprises a rotor (12) comprising two pole wheels (24, 25), said coil (31) being mounted wedged, without play, between said two pole wheels ( 24, 25). 1/3 2/3