FR3088498A1 - STATOR BODY PROVIDED WITH AN ELECTROTECHNICAL HEAD OF REDUCED THICKNESS - Google Patents

Abstract

The invention relates mainly to a stator body (43) for a rotary electric machine, in particular for a motor vehicle, comprising: - an electrotechnical yoke (51) allowing the circulation of a magnetic flux, - teeth (52) coming from 'an internal periphery of the electrotechnical yoke (51) delimiting notches (54) intended to receive the conductors of a winding, characterized in that said electrotechnical yoke (51) has a radial thickness (L5) chosen to the minimum necessary to avoid a magnetic saturation of said electrotechnical yoke (51), and in that said stator body (43) further comprises notches (57) of mechanical support coming from an external periphery of the yoke (51), a notch ( 57) of mechanical support extending over an angular range (P) corresponding to at least two teeth (52).

Description

STATOR BODY HAVING AN ELECTROTECHNICAL HEAD OF REDUCED THICKNESS

The present invention relates to a stator body provided with a cylinder head of reduced thickness. 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 an alternator starter, makes it possible to transform electrical energy into mechanical energy, in particular for starting the vehicle's heat engine. The invention can also be implemented with an electric motor.

In a manner known per se, an alternator or an alternator-starter 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 rotor, for example with claws, 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 an excitation winding making it possible to generate the north and south poles of the rotor when it is traversed by a current. The rotor can also take the form of a permanent magnet rotor.

Furthermore, the stator comprises a body constituted by a stack of thin sheets comprising a cylinder head and teeth from an internal periphery of the cylinder head. These teeth define notches intended to receive the conductors of a winding.

These conductors pass through the notches in the stator body and form buns projecting from either side of the stator body. The conductors take, for example, the form of continuous wires covered with enamel or of conductive elements in the form of pins connected together by welding.

The breech of the stator body aims to allow the circulation of a magnetic flux inside the stator. Mechanical constraints (assembly constraints, resistance to pollution for example) are added to this electrotechnical constraint, so that the total thickness of the cylinder head is oversized compared to the thickness really effective for the passage of the flux magnetic.

Indeed, as illustrated in FIG. 1, it is necessary to provide an additional width L1 linked to an offset of the winding bun 1 towards the outside of the stator body 2 due to compaction of the bun 1, a minimum clearance L2 to be observed between the bun 1 and the bearing 3 in order to avoid salt bridges, a radial gap L3 due to the clearance of the bearing 3, and an area L4 of minimum support of the package against which a shoulder of a bearing comes to bear 3.

The invention aims to reduce the amount of material in the cylinder head by proposing a stator body for a rotary electrical machine, in particular for a motor vehicle, comprising:

- an electrotechnical yoke allowing the circulation of a magnetic flux,

- teeth from an internal periphery of the electrotechnical yoke defining notches intended to receive the conductors of a winding, characterized in that said electrotechnical yoke has a radial thickness chosen at the minimum necessary to avoid magnetic saturation of said electrotechnical yoke ,

- And in that said stator body further comprises mechanical support notches from an external periphery of the cylinder head, a mechanical support notch extending over an angular range corresponding to at least two teeth.

The invention thus makes it possible, thanks to the presence of the mechanical support notches, to reduce the mass of the stator body by limiting the thickness of the cylinder head, and this without deteriorating the performance of the rotary electrical machine. Thus, it is possible to gain 50 to 200 g of material depending on the machine considered. The invention also makes it possible to bring the tie rods closer to the axis of the machine and therefore to reduce the radial size of the latter.

According to one embodiment, a mechanical support notch extends over an angular range corresponding to at least three teeth.

According to one embodiment, a mechanical support notch extends over an angular range corresponding to at least four teeth.

According to one embodiment, a radial thickness of the electrotechnical yoke is between 2 times and 2.5 times a smaller width of a tooth.

According to one embodiment, a mechanical support notch has a radial height of between 1 and 3 mm.

According to one embodiment, an axial width of a mechanical support notch is equal to an axial height of the electrotechnical yoke.

According to one embodiment, said stator body comprises a number of notches selected in particular from 36, 72, or 96 notches.

According to one embodiment, said stator body is formed by an axial stack of sheets made of a magnetic material.

According to one embodiment, said stator body is formed by sheets made of a magnetic material and wound in a spiral with respect to each other.

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

According to one embodiment, said rotary electric machine comprises two bearings each carrying a bearing for the rotational mounting of a shaft, each bearing coming into mechanical support, via a shoulder, against an axial end face of a notch of mechanical support .

According to one embodiment, said rotary electrical machine comprises tie-rods for fixing the bearings, so that the stator body is kept clamped axially between the bearings.

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, already described, is a sectional view illustrating the different dimensions to be taken into consideration for the dimensioning of a cylinder head of a stator body according to the prior art;

Figure 2 is a longitudinal sectional view of a rotary electrical machine according to the present invention;

Figure 3 is a perspective view of a stator body according to the present invention;

Figure 4 is a partial top view of a stator body according to the present invention.

In FIGS. 2 to 4, identical, similar or similar elements retain the same reference from one figure to another.

FIG. 2 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. A reversible alternator, called an alternator-starter, makes it possible to transform electrical energy into mechanical energy in particular for starting the thermal 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. The axis X along which the shaft 13 extends forms the axis of the electric machine.

The casing 11 comprises front 17 and rear 18 bearings carrying the stator 16. The bearings 17, 18 are hollow in shape and each carry a ball bearing 20, 21 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 the 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 relative to each 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 on its outer periphery a winding d excitation 31 wound in an insulator 32 inserted radially between the core 30 and the coil 31.

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 carries a pulley 35 belonging 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 described in more detail below as well as a winding 42 forming a front bun 44 and a rear bun 45 extending on either side of the stator body 43. The winding 42 is produced from conductors constituted for example by continuous wires covered with enamel or with conductive elements in the form of pins electrically connected to each other in particular by welding.

The winding 42 includes phase outputs connected to an electronic control module 47. This module 47 notably comprises an inverter and / or a rectifier bridge constituted for example by diodes or transistors of the MOSFET type.

A protective cover 50 is positioned around the electronic control module 47 to protect it from dirt and splashes of liquid during the use of the motor vehicle.

In order to ensure cooling of the electric machine 10, fans 48 fixed on the axial ends of the rotor 12 make it possible to generate an air flow to dissipate the heat produced by the stator 16 as well as by the electronic control module 47. To this end, the air flow passes through vents 49 formed in the front bearing 17 and the rear bearing 18.

As can be seen in Figures 3 and 4, the stator body 43 includes an electrotechnical yoke 51 allowing the circulation of a magnetic flux inside the stator 16. Teeth 52 from an internal periphery of the yoke electrotechnical 51 delimit notches 54 intended to receive the conductors of the winding 42. The teeth 52 delimit two by two of the notches 54, so that there is an alternation of teeth 52 and notches 54 along a circumference of the stator 16. The stator body 43 includes a number of notches 54 selected in particular from 36, 72, or 96 notches. It would of course be possible to envisage any other number of notches 54 adapted to the application. The notches 54 may be with parallel edges or not.

The electrotechnical yoke 51 corresponds to the strip of material extending between the bottom of the notches 54 and the external periphery of the stator body 43 and through which the flux of the stator passes. The electrotechnical yoke 51 has a radial thickness L5 chosen at minimum necessary to avoid magnetic saturation of the electrotechnical yoke 51. A radial thickness L5 of the electrotechnical yoke 51 is advantageously between 2 times and 2.5 times a smaller width L6 of a tooth 52.

In addition, the stator body 43 comprises notches 57 of mechanical support coming from an external periphery of the cylinder head 51. A notch 57 extends 52 over an angular range P corresponding to at least four teeth

52, preferably at least five teeth 52 to form sufficient mechanical support with the bearings 17, 18.

According to an exemplary embodiment, a support notch 57 has a radial height L7 of between 1 and 3mm. An axial width L8 of a support notch 57 is equal to an axial height of the electrotechnical yoke 51. In other words, a notch 57 extends along the entire axial height of the yoke 51. Two successive notches 57 are separated from each other by a circumferential clearance 58. The notches 57 may be distributed angularly in a regular manner along the circumference of the stator body 43.

The stator body 43 may be formed by an axial stack of magnetic sheets. In this case, the sheets are assembled together by means of a suitable fixing system, such as rivets, buttoning, or by welding.

Alternatively, the stator body 43 is formed by magnetic sheets wound in a spiral with respect to each other.

According to an assembly of the electric machine 10, each bearing 17, 18 comes into mechanical support, via a shoulder, against an axial end face of a support notch 57. The external diameter of a notch 57 being greater than the diameter external of the electrotechnical yoke 51, the stator body 43 is not in contact with the bearing 17, 18 over its entire circumference, but only along the notches 57 of mechanical support. The bearings 17, 18 are assembled together by means of fixing tie rods, so that the stator body 43 is held axially clamped between the bearings 17 and 18.

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. Stator body (43) for a rotary electrical machine (10), in particular for a motor vehicle, comprising: - an electrotechnical yoke (51) allowing the circulation of a magnetic flux, - Teeth (52) from an internal periphery of the electrotechnical yoke (51) delimiting notches (54) intended to receive the conductors of a winding (42), characterized in that said electrotechnical yoke (51) has a radial thickness (L5) chosen at the minimum necessary to avoid magnetic saturation of said electrotechnical yoke (51), - And in that said stator body (43) further comprises notches (57) of mechanical support coming from an external periphery of the cylinder head (51), a notch (57) of mechanical support extending over a range angular (P) corresponding to at least two teeth (52). 2. stator body according to claim 1, characterized in that a radial thickness (L5) of the electrotechnical yoke (51) is between 2 times and 2.5 times a smaller width (L6) of a tooth (52) . 3. stator body according to claim 1 or 2, characterized in that a mechanical support notch (57) has a radial height (L7) between 1 and 3mm. 4. stator body according to any one of claims 1 to 3, characterized in that an axial width (L8) of a mechanical support notch (57) is equal to an axial height of the electrotechnical yoke (51) . 5. stator body according to any one of claims 1 to 4, characterized in that it comprises a number of notches (54) selected in particular from 36, 72, or 96 notches. 6. stator body according to any one of claims 1 to 5, characterized in that it is formed by an axial stack of sheets made of a magnetic material. 7. stator body according to any one of claims 1 to 5, characterized in that it is formed by sheets made of a magnetic material and wound in a spiral with respect to each other. 8. Rotating electric machine (10) characterized in that it comprises a stator body (43) as defined according to any one of the preceding claims. 9. rotary electric machine according to claim 8, characterized in that it comprises two bearings (17, 18) each carrying a bearing (20, 21) for the rotational mounting of a shaft (13), each bearing (17 , 18) ίο coming into mechanical support, via a shoulder, against an axial end face of a notch (57) of mechanical support. 10. Rotating electric machine according to claim 9, characterized in that it comprises tie-rods for fixing the bearings (17, 18), so that the stator body (43) is kept tight. 15 axially between the bearings (17, 18).