FR3052001A1 - ROTATING ELECTRIC MACHINE WITH IMPROVED CONFIGURATION - Google Patents

Abstract

The invention relates mainly to a rotary electric machine (10) comprising a claw rotor (12) and a stator (16) surrounding said claw rotor (12) with the presence of an air gap (14) between an inner periphery of said stator (16) and an outer periphery of said claw rotor (12), said stator (16) having at least one polyphase winding and a body (43) having a plurality of notches (48) each delimited by two teeth (44). ) successive, characterized in that for a rotary electric machine (10) having p pole pairs, said claw rotor (12) has 2p claws (29) and said stator (16) has 3p teeth (44).

Description

ROTATING ELECTRICAL MACHINE WITH ENHANCED CONFIGURATION

The present invention relates to a rotating electrical machine with improved configuration. 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.

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.

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 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.

Furthermore, the stator comprises a body consisting of a stack of thin sheets forming a ring, whose inner face is provided with notches open inwardly 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. This rectifier bridge comprises rectifier elements constituted for example by MOSFET type transistors.

For conventional windings, there are difficulties in cutting the sheet and inserting the winding in particular because of the large number of notches, the small opening size of the notch, the low filling rate, and the fragility of insertion tools. The invention aims to remedy these drawbacks effectively by proposing a rotating electrical machine comprising a claw rotor and a stator surrounding said claw rotor with presence of an air gap between an inner periphery of said stator and an outer periphery of said claw rotor, said stator comprising at least one polyphase winding and a body provided with a plurality of notches each delimited by two successive teeth, characterized in that for a rotary electric machine comprising p pairs of poles, said claw rotor comprises 2p claws and said stator has 3p teeth. The invention thus makes it easier to perform the winding by reducing the number of stator teeth for a given number of poles while minimizing the magnetic noise of the electric machine. The invention is particularly suitable for making small machines at low cost easier to wind.

In one embodiment, said rotating electrical machine comprises a three-phase winding.

According to one embodiment, said rotating electrical machine comprises two independent three-phase windings.

According to one embodiment, the winding or windings are of concentrated type and comprise a plurality of coils, each coil being wound around a corresponding tooth of said stator.

In one embodiment, said coils of each phase are electrically connected in series or in parallel.

In one embodiment, each tooth receives at least two coils each associated with a separate winding.

According to one embodiment, the winding or windings are of corrugated type.

According to one embodiment, the phases of the winding or windings are coupled in a triangle.

According to one embodiment, the phases of the winding or coils are star-coupled.

According to one embodiment, said rotating electrical machine comprises internal axial ventilation means.

According to one embodiment, said stator comprises a variable tooth profile. This makes it possible to optimize the compromise between the current flow and the noise of the electric machine.

According to one embodiment, said air gap is 100% in an axis of at least one tooth of said stator, and increases up to 250% on edges of said tooth. The invention will be better understood on reading the description which follows and the examination of 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 partial sectional view of a stator according to the present invention provided with a corrugated type winding;

Figure 3 is a partial perspective view of the stator body used with a concentrated type winding;

Figures 4a and 4b are perspective views of a coil / coil insulator assembly respectively before and after mounting it by threading on an associated stator tooth;

Figure 5 is a partial sectional view of a stator with a concentrated winding illustrating the shape of the opening between two adjacent coils allowing the passage of air inside the electrical machine;

Figure 6 is a partial sectional view of a wound stator illustrating an alternative embodiment in which two coils are implanted on each tooth.

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 housing 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 14 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 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 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 comprise a threaded portion for the attachment of a rotor. 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. More specifically, the brush holder 38 comprises a housing having dwellings intended to each receive a broom.

Furthermore, as shown in Figures 2, 3, 5 and 6, the stator 16 comprises a body 43 consisting of an axial stack of flat sheets. The stator body 43 has teeth 44 distributed angularly in a regular manner on an inner periphery of a yoke 45. These teeth 44 delimit notches 48, so that each notch 48 is delimited by two successive teeth 44.

The notches 48 open axially into the axial end faces of the stator body 43. The notches 48 are also open radially towards the inside of the stator body 43. The stator 16 may be provided with tooth roots 50 on the ends free of teeth 44, as shown in Figures 2, 5 and 6. Each tooth root 50 extends circumferentially on either side of a corresponding tooth 44. The notches 48 are preferably equipped with notch insulation for mounting the phases of the stator 16.

In a wave-type winding shown in FIG. 2, each phase comprises at least one phase winding 49 passing through the notches 48 of the stator body 43. This phase winding 49 forms, with all the phases, a front bun 46 and a rear bun 47 on either side of the stator body 43, as can be seen in FIG. 1. The phase windings 49 are obtained for example from a continuous wire covered with enamel or from conductive elements in the form of pins electrically connected together for example by welding. The phase windings 49 are electrically connected to electronic power modules via their phase output.

These power modules form a voltage rectifier bridge for converting the alternating voltage generated by the alternator 10 into a DC voltage to supply the battery and the on-board vehicle network, in particular. The power modules may also be controlled to inject current into the different phases of the electric machine when the latter operates in motor mode.

To form the winding, several phase windings 49 are installed in the notches 48 of the body 43. In the example shown, the machine comprises two independent three-phase windings Al, B1, C1 and A2, B2, C2 coupled together. In a variant, the winding is a single three-phase winding. The phases of the winding or windings may be coupled in a triangle or star.

Each phase winding 49 is constituted by at least one continuous conductor wound inside the stator in the notches 48 to form one or more turns. Each phase A1, B1, C1, and A2, B2, C2 is associated with a series of notches 48 of the set of notches, so that each notch 48 receives several times the conductors of the same phase.

Two consecutive notches in one series are separated by adjacent notches each corresponding to another series of notches associated with one of the other phases A1, B1, C1, and A2, B2, C2. Thus, when there are K phases, the conductors of the same phase winding are inserted all the K + 1 notches. For example, if the Al phase is inserted into the slot No. 1, it is then inserted into the 7th notch for a machine with two three-phase windings, K = 6.

In the embodiment of FIGS. 5 and 6, the winding is of concentrated type. In this case, each phase winding 49 comprises a plurality of coils 52 visible in FIGS. 4a and 4b. These coils 52 are made from a wire 53 wound on several turns to form several turns. The wire 53 may be of round or rectangular section. It will also be possible to use two or more parallel wires to perform the winding operation. A coil insulator 55 is preferably interposed between each coil 52 and the corresponding tooth 44 of the stator 16.

To improve the cooling of the winding stators on teeth 44, coils 52 of rectangular section are used, which leaves triangular section passages 54 between the coils 52, as illustrated in FIG. air through passages 54 using internal axial ventilation means. As can be seen in FIG. 1, the ventilation means comprise two fans 57 each fixed at one axial end of the rotor 12. The coils 52 are mounted around teeth 44 with parallel edges.

According to the invention, for an electrical machine comprising P pairs of poles, the rotor 12 comprises 2p claws and the stator 16 comprises 3p teeth 44.

In an exemplary embodiment, a machine with 24 stator teeth can replace a conventional equivalent machine 48 stator slots by delivering substantially the same electromotive force against a single rotor with 16 claws. The winding will be easier with 24 coils on all identical tooth having nine or ten turns, connected by eight in parallel for each phase to a connector where the phase outputs can be freely distributed over 360 degrees. In the case of a coil type concentrated, the number of turns may be between 8 and 11 for example. In the case of a corrugated winding, it will be possible to make between 0.5 and 1 turn by phase winding.

In the case of a machine with three-phase double coils, for example 12 volts and 48 volts, the number and the diameter of the wires 53 of each coil 52 can be adjusted according to the electromotive force and the rated intensity with a large finesse to optimize each winding.

In an exemplary embodiment, a 12Volts and 48Volts double-coil machine has 16 poles and 24 stator teeth with equal nominal power on both circuits.

Each tooth 44 may receive two separate coils 52, 52 '. The first coil 52 has ten turns of diameter 1.60 mm for the winding of 12 volts. There are eight coils 52 electrically connected in parallel per phase.

The second coil 52 'has 40 turns with a diameter of 0.80 for the winding of 48 volts. It will be possible to provide eight coils 52 electrically connected in parallel per phase.

As a variant, the second coil 52 comprises ten turns with a diameter of 1.60 mm and four coils 52 electrically connected in series in two channels in parallel per phase are provided. By using two coils 52, 52 'having the same wire diameter, this makes it easier to perform the winding operation.

The coils 52, 52 'can be wound on one another. But they are preferably separated along the tooth 44 on a compartmentalized molded coil insulator 55, as shown in FIG. 6. This facilitates winding and connection to the corresponding connectors. The connectors can be included in a common molded part.

Of course, it is possible to make more than two independent windings.

In order to optimize the compromise between the current flow rate and the magnetic noise of the machine with 2p poles and 3p teeth, it is possible to change the air gap 14 under each stator tooth 44 by producing in particular a variable tooth profile 60, as illustrated. 5. The gap 14 can thus be 100% in the axis of the tooth 44, and increase up to 250% on the edges of the tooth 44. The gap 14 can be asymmetrical.

The tooth 44 can also be asymmetrical with unequal feet of teeth 50. The shape of the tooth 44 being obtained by cutting, there is no additional cost to complicate it if necessary.

It then becomes possible to use single claw-shaped rotors without chamfers on the claws, insofar as the dynamic gap variation 14 can be managed by acting only on the side 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 (12)

A rotating electric machine (10) comprising a claw rotor (12) and a stator (16) surrounding said claw rotor (12) with an air gap (14) between an inner periphery of said stator (16) and a outer periphery of said claw rotor (12), said stator (16) having at least one polyphase winding (A1, B1, Cl; A2, B2, C2) and a body (43) having a plurality of notches (48). ) delimited each by two successive teeth (44), characterized in that for a rotary electric machine (10) comprising p pairs of poles, said claw rotor (12) comprises 2p claws (29) and said stator (16) comprises 3p teeth (44). 2. Rotary electrical machine according to claim 1, characterized in that it comprises a three-phase winding. 3. Rotating electrical machine according to claim 1, characterized in that it comprises two independent three-phase windings (Al, B1, C1, A2, B2, C2). Rotary electric machine according to any one of claims 1 to 3, characterized in that the winding or windings (A1, B1, C1, A2, B2, C2) are of concentrated type and comprise a plurality of coils (52). each coil (52) being wound around a corresponding tooth (44) of said stator. 5. The rotary electrical machine according to claim 4, characterized in that said coils (52) of each phase are electrically connected in series or in parallel. 6. A rotary electric machine according to claims 3 and 4, characterized in that each tooth (44) receives at least two coils (52, 52 ') each associated with a separate winding. 7. A rotary electric machine according to any one of claims 1 to 3, characterized in that the winding or windings (A1, B1, C1, A2, B2, C2) are of corrugated type. 8. rotary electric machine according to any one of claims 1 to 7, characterized in that the phases of the winding or coils are coupled in a triangle. 9. rotary electric machine according to any one of claims 1 to 7, characterized in that the phases of the winding or coils are coupled in a star. 10. rotary electric machine according to any one of claims 1 to 9, characterized in that it comprises internal axial ventilation means (57). 11. A rotary electric machine according to any one of claims 1 to 10, characterized in that said stator (16) comprises a variable tooth profile (60). 12. A rotary electric machine according to claim 11, characterized in that said air gap (14) is 100% in an axis of at least one tooth (44) of said stator (16), and increases up to 250% on edges of said tooth (44).