FR3054743B1 - 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

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 convert electrical energy into mechanical energy, in particular to start the engine of the vehicle. The invention may also be implemented with an electric motor.

In a manner known per se, an alternator comprises a housing 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 forming a ring, the inner face of which is provided with notches open towards the inside to receive phase windings. These windings pass through the notches of the stator body and form buns protruding from both sides 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 including a rectifier bridge.

Furthermore, the rotor comprises two pole wheels each having a transversely oriented flange provided at its outer periphery axially oriented claws. The claws of the pole wheels are nested with respect 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 inserted radially between the core and the coil. A varnish deposited during a step of impregnating the rotor ensures a mechanical holding of the coil.

The conventional configuration of the rotor requires to provide a large clearance between the flanges and the axial ends of the coil to prevent deformation of the coil during assembly and compensate for the dimensional variabilities of the coil insulation. There are also crossing son during winding increasing the size of the coil. In addition, the current coil is slightly cooled by convection due to the existing vacuum between the front and rear flanges of the rotor.

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

a winding comprising a plurality of turns made from a thermosetting wire,

said winding being coated with an elastic layer having an electrical insulator function.

The invention thus ensures electrical insulation of the coils while avoiding the dimensional variability of the coil insulation usually used. By controlling the space occupied by the coil, the invention allows a reduction of axial play between the coil and the pole wheels. The invention also improves the vibration resistance of the coil and is of economic interest, insofar as it is possible to remove the varnish impregnation step.

In 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 removed by conduction and thus to better control its temperature during the operation of the alternator. Due to a better cooling of the coil, one improves its magnetic performance of flow generation.

According to one embodiment, said elastic layer is loaded with additives that promote heat dissipation.

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

Because of the connection between the turns, the winding obtained has rows of regular turns in which wire crossings are avoided to the maximum. This improves the filling rate of the rotor 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 holding flanges serve to ensure the centering of the coil with respect to the injection mold and with respect to the pole wheels during assembly of the rotor.

According to one embodiment, each holding flange comprises a centering flange cooperating with an inner periphery of said winding.

According to one embodiment, each retaining flange comprises feet extending axially in the opposite direction of said winding, each leg being intended to engage in a space between an active element of said rotating electrical machine.

According to one embodiment, each holding flange comprises a plurality of through orifices, an axis of each through orifice being parallel to an axis of revolution of said winding.

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

According to one embodiment, said rotating 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 for illustrative but not limiting of 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 reel according to the present invention;

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

Fig. 4 is a cross-sectional view of a coil wire 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 and polyphase 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 alternator-starter, makes it possible to convert electrical energy into mechanical energy, in particular to start the 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. rotor 12 and the inner periphery of the stator 16. The axis X along which the shaft 13 extends forms the axis of rotation of the rotor 12.

The housing 11 comprises front 17 and rear 18 bearings bearing the stator 16. The bearings 17, 18 are of hollow form and each carry a central ball bearing 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 a 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 a gap between two claws 29 adjacent to the other pole wheel, so that the claws 29 of the pole wheels 24, 25 are interlocked with respect to other.

A cylindrical core 30 is interposed axially 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 at its outer periphery a coil of excitation 31 described in more detail below.

The shaft 13 can be force-fitted into the central bore of the pole wheels 24, 25. On the side of its front end, the shaft 13 may comprise a threaded portion for fixing a pulley 35. The pulley 35 belongs to a device for transmitting movements to 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 manifold 41 to supply the winding of the rotor 12.

Furthermore, the stator 16 comprises a body 43 in the form of a sheet metal package provided with notches equipped with notch insulation 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 comprises in particular 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, continuous wire. Winding 50 is furthermore 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 discharge the heat generated by the coil 31 by conduction. Due to a better cooling of the coil 31, it improves its magnetic generation performance. flux. If necessary, the elastic layer 55 is loaded with additives that promote heat dissipation. The elastic layer 55 of coating 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, 15 and the cylindrical peripheries. internal 60 and outer 61 of I winding 50. The coating layer 55 may be made by injection of a silicone material into a corresponding mold. The winding 50 of the coil 31 is thus completely embedded in the silicone material.

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

The connection between the adjacent turns 51 of the coil 31 is obtained by passing a high intensity current in the wire 52 after the embodiment of the winding 50 on a support. This has the effect of heating the second layer of enamel 66 which will polymerize 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 thread crossings 52 are avoided to the maximum. This improves the filling rate of the rotor 12 active material.

Preferably, the silicone-coated coil 31 is mounted between two holding flanges 70. As illustrated in FIGS. 5a and 5b, each Z-axis holding flange 70 comprises a ring-shaped wall 71. The Z axis is substantially coincident with the Y axis of the winding when the holding flange 70 is pressed against the winding 50.

A centering flange 72 has an annular shape of axial orientation. This flange 72 is derived from an inner periphery of the ring 71. The flange 72 is intended to be inserted into the internal opening 75 of the winding 50 so as to cooperate with the inner periphery 60 of the winding 50. For this purpose, the flange 72 has an outer 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 of the winding 50. Each leg 78 is intended to engage in a space between a corresponding pole wheel 24, 25 .

The feet 78 make it possible to ensure the centering of the coil 31 with respect to the pole wheels 24, 25 during the assembly of the rotor 12. This ensures a 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 perform the centering of the coil 31 relative to the silicone resin injection mold.

Each holding flange 70 preferably comprises a plurality of through holes 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 degree of filling of the rotor 12 or isoperformance to reduce its bulk, the coil 31 is mounted wedged without play between the two pole wheels 24, 25. Thanks to the silicone layer 55, the coil 31 will be put under stress during the packing of the rotor 12 thus avoiding any possible vibration during operation of the alternator.

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

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention which would not be overcome by replacing the different elements by any other equivalent.

In addition, the various features, variations, and / or embodiments of the present invention may be associated with each other in various combinations, to the extent that they are not incompatible or exclusive of each other.

Claims (10)

1. Coil (31) for a rotary electric machine (10) characterized in that it comprises: a winding (50) comprising a plurality of turns (51) made from a thermosetting wire (52), said thermosetting wire (52) having a conductive core (64) covered with a first enamel layer (65); ) providing electrical insulation, a second layer of enamel (66) solidarisant two adjacent turns (51) of said winding (50), and an intermediate bonding layer (67) providing a mechanical connection between said first layer of enamel enamel (65) and said second enamel layer (66). said winding (50) being coated with an elastic layer (55) having an electrical insulator 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 (55) is loaded with additives promoting heat dissipation. 4. Coil according to claim 3, characterized in that said thermosetting wire (52) comprises a conductive core (64) made of copper or aluminum. 5. Coil according to any one of claims 1 to 4, characterized in that said winding (50) is mounted between two holding flanges (70). 6. Coil according to claim 5, characterized in that each retaining flange (70) comprises a centering flange (72) cooperating with an inner periphery (60) of said winding (50). 7. Coil according to claim 5 or 6, 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 for s' engaging in an entrance space of an active element of said rotating electrical machine (10). 8. Coil according to any one of claims 5 to 7, characterized in that each retaining flange (70) comprises a A plurality of through orifices (83), one axis of each through orifice (83) being parallel to an axis of revolution (Y) of said winding (50). 9. Rotating electrical machine (10) characterized in that it comprises a coil (31) as defined in any one of the preceding claims. ίο 10. Rotating electrical machine according to claim 9, 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).