FR3066659A1 - ROTATING ELECTRIC MACHINE WITH A BEARING HAVING A CONFINED INTERNAL SIDE FOR IMPROVING COOLING - Google Patents

Abstract

The invention relates mainly to a rotating electric machine for a motor vehicle comprising: - a stator comprising a body and a coil (18) provided with buns (20) extending on either side of the stator body, - at least a bearing (35) having a plate (53) and a skirt (54), - the bearing (35) having an inner face (62) facing a winding bun (20) and lateral openings for the passage of air cooling device, characterized in that the inner face (62) comprises an inclined peripheral portion (64) with respect to a plane (P1) orthogonal to an axis (X) along which the stator extends so as to increase a space ( 67) for the cooling air passage between the winding bun (20) and the bearing (35).

Description

ROTATING ELECTRIC MACHINE HAVING A BEARING HAVING AN INTERNAL FACE CONFIGURED TO IMPROVE

THE RECOOLING

The present invention relates to a rotary electric machine provided with a bearing having an internal face configured to improve cooling.

The invention finds a particularly advantageous, but not exclusive, application in the field of alternators and reversible electrical machines for a motor vehicle. An alternator transforms mechanical energy into electrical energy. A reversible machine also makes it possible to transform electrical energy into mechanical energy, in particular for starting the vehicle's heat engine.

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. A pulley attached to the front end of the shaft belongs to a belt movement transmission device between the engine and the electric machine.

The stator has a body in the form of a packet of sheets provided with notches for mounting the phase windings of the stator winding. These phase windings form buns extending projecting on either side of the stator body. These phase windings are for example three-phase windings connected in star or in triangle, the outputs of which are connected to at least one electronic rectification module comprising rectifier elements, such as diodes or transistors.

Furthermore, the rotor has two pole wheels. Each pole wheel has a transverse orientation flange provided at its outer periphery with claws, for example of trapezoidal shape. The claws of one wheel are directed axially towards the flange of the other wheel. Each claw of a pole wheel enters the space between two claws adjacent to the other pole wheel, so that the claws of the pole wheels are nested relative to each other.

The rotor shaft is rotated by the front bearing and the rear bearing of the housing. For this purpose, the bearings are hollow in shape and are each provided centrally with a ball bearing. The bearings have axial and lateral openings in order to allow the alternator to cool by air circulation generated by the rotation of fans positioned on the end faces of the rotor. Each fan is provided with a plurality of blades. The side openings in the bearings are located opposite the corresponding buns.

However, it has been observed that the alternator could encounter overheating during tests carried out at high temperatures, of the order of 100 ° C. in particular, representative of the significant thermal stresses in the environment under the hood of the vehicle in which is located the rotating electric machine.

The invention aims to effectively remedy this drawback by proposing a rotating electric machine for a motor vehicle comprising:

a stator comprising a body and a winding provided with buns extending on either side of the stator body,

- at least one bearing comprising a plate and a skirt,

- the bearing comprising an internal face turned towards a winding bun and lateral openings for the passage of cooling air, characterized in that the internal face comprises a peripheral portion inclined relative to a plane orthogonal to an axis along which s extends the stator so as to increase a space for the passage of cooling air between the winding chignon and the bearing.

The invention thus makes it possible, thanks to the inclined peripheral portion of the internal face of the bearing, to increase the air flow at the level of the buns, which improves the cooling of the stator and therefore of the electric machine which heats up makes current flow inside the winding.

According to one embodiment, the inclined peripheral portion of the internal face forms an angle between 5 and 25 degrees relative to the plane orthogonal to the axis along which the stator extends.

According to one embodiment, the inclined peripheral portion is arranged so that, in a plane passing through the axis along which extends the stator, the cooling air passage space increases in a radial direction away from axis.

According to one embodiment, the inclined peripheral portion extends circumferentially at least between two adjacent fins defining a lateral opening.

According to one embodiment, the inclined peripheral portion extends along the entire circumference of the bearing.

According to one embodiment, at least one fin forms a rounded connection between the inclined peripheral portion and the skirt.

According to one embodiment, the inclined peripheral portion opens into a lateral opening.

According to one embodiment, the skirt comprises at least one through hole for the passage of a fixing member to keep the bearing in abutment against the stator body or against the body of another bearing.

According to one embodiment, the internal face of the bearing comprises a central annular portion extending in a plane orthogonal to the axis along which the stator extends, the inclined peripheral portion being located in the extension of the central annular portion.

According to one embodiment, said rotary electrical machine comprises a rotor and a fan fixed on an axial end face of the rotor, an external diameter of the central annular portion being substantially equal to an external diameter of the fan.

According to one embodiment, the inclined peripheral portion is arranged opposite the winding bun.

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 is a partial perspective view of a bearing of the rotary electric machine according to the present invention;

Figure 3 is a partial sectional view illustrating the configuration of the internal face of the bearing of the rotary electric machine according to the invention;

Figure 4 is a perspective view illustrating the rear bearing holding tool during assembly of the rotary electric machine according to the invention;

Figure 5 is a perspective view illustrating the clamping portions against which abuts the bearing holding tool of the rotary electric machine according to the invention.

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

FIG. 1 shows a compact, multi-phase alternator 10, in particular for a motor vehicle. This alternator 10 transforms mechanical energy into electrical energy and can be reversible. Such a reversible alternator 10, 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. A pulley 14 is fixed on the shaft 13. This pulley 14 belongs to a belt movement transmission device between the alternator 10 and the heat engine of the motor vehicle. Alternatively, the pulley 14 is replaced by a cup directly driven by the heat engine.

The stator 16 extends along an axis X coaxial with the axis of the shaft 13. The stator 16 comprises a body 19 in the form of a pack of sheets provided with teeth delimiting notches for mounting a winding 18 The winding 18 comprises phase windings passing through the notches of the stator body 19 and forming a front bun 20 and a rear bun 21 projecting on either side of the stator body 19.

The phase windings are obtained for example from a continuous wire covered with enamel or from conductive elements in the form of a bar, such as pins connected to each other for example by welding. These windings are for example three-phase windings connected in a star or a triangle, the outputs of which are connected to at least one rectifier bridge comprising rectifier elements such as diodes or transistors of the MOSFET type, in particular when it is a question of an alternator starter as described for example in the document FR2745445.

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. The claws 29 of one wheel 24, 25 are directed axially towards the flange 28 of the other wheel. Each claw 29 of a pole wheel 24, 25 enters the space 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 at its outer periphery a coil d excitation 31 wound in an insulator radially interposed between the core 30 and the coil 31.

Furthermore, the casing 11 has front 35 and rear 36 bearings assembled with one another by means of fixing members, such as tie rods. The bearings 35, 36 are hollow in shape and are each provided centrally with a receiving housing 37, 38 with a ball bearing for the rotational mounting of the shaft 13 of the rotor. The rear bearing 36 carries a brush holder 40 provided with brushes 41 intended to rub against the rings 44 of a collector 45 connected by wire connections to the excitation winding

31. The brushes 41 are electrically connected to a voltage regulator.

The front 35 and rear 36 bearings have axial 50 and lateral 51 openings in order to allow the alternator 10 to cool by air circulation generated by the rotation of fans 48 fixed on the end faces of the rotor 12. Each ventilator 48 is provided with a plurality of blades 49. The lateral openings 51 are situated opposite the corresponding front 20 and rear 21 buns.

More specifically, as can be seen in FIG. 2, the front bearing 35 comprises a plate 53 of generally transverse orientation and a skirt 54 coming from an external periphery of the plate 53 extending axially along the axis X. The axial openings 50 are produced in the plate 53. The lateral openings 51 are formed at least in the skirt 54. In fact, if necessary, a portion of the lateral openings 51 may extend in the plate 53.

The lateral openings 51 are delimited by fins 57. There is thus an alternation of openings 51 and fins 57 along the circumference of the bearing 35, two successive openings 51 being separated by a fin 57.

In addition, the skirt 54 has at least one through hole 59 for the passage of a fixing member, such as a tie rod, to hold the bearing 35 in abutment against the stator body 19 or against the other bearing 36. The bearing 35 also includes protruding ears perforated 60 to allow the fixing of the rotary electric machine 10 on a fixed element of the vehicle body.

As can be seen in FIG. 3, the bearing 35 comprising an internal face 62 oriented towards the winding chignon 20. The internal face 62 of the bearing 35 comprises a central annular portion 63 extending in an orthogonal plane P1 relative to the axis X, as well as a peripheral annular portion 64 situated in the extension of the central portion 63. The peripheral portion 64 is inclined relative to the plane P1 so as to increase the space 67 for the passage of cooling air between the bun 21 and the bearing 35. The central annular portion 63 as well as the inclined peripheral portion 64 are formed in the internal face 62 of the plate 53 of the bearing 35.

More specifically, the external diameter of the central annular portion 63 is substantially equal to the external diameter of the corresponding fan 48. By substantially equal is meant that there is a maximum difference of 10% between these two diameters. The planar central annular portion 63 extends opposite the blades 49 of the fan 48, that is to say that there is at least one straight line of axial orientation passing both through the central portion 63 and a corresponding blade 49. Such a configuration makes it possible to optimize the air flow generated by the fan 48. The axial openings 50 are made in the central annular portion 63.

Furthermore, the inclined peripheral portion 64 is arranged opposite the corresponding winding bun 20, that is to say that there is at least one straight line of axial orientation passing both through the inclined peripheral portion 64 and the corresponding winding bun 20.

The inclined peripheral portion 64 is arranged so that, in a plane passing through the axis X corresponding to the plane of the sheet in FIG. 3, the space 67 for the passage of cooling air increases in a radial direction in s' away from the axis X. To this end, the thickness of the plate 53 decreases by moving radially from the axis X towards a lateral opening 51 of the bearing 35.

In this case, the inclined peripheral portion 64 extends along the entire circumference of the bearing 35. Between two fins 57, the inclined peripheral portion 64 opens into a lateral opening 51. Between two lateral openings 51, a fin 57 forms a rounded of connection 65 between the inclined peripheral portion 64 and the skirt 54 of the bearing 35.

In an advantageous exemplary embodiment, the inclined peripheral portion 64 of the internal face 62 forms an angle A of between 5 and 25 degrees relative to the plane P1 orthogonal to the axis X.

As illustrated in FIG. 4, during assembly of the electric machine 10, the bearing 35 is held tight against a tool 70 comprising for this purpose rods 71 provided with heads 72 passing inside the corresponding axial openings 50. Once the rods 71 have passed through the axial openings 50, the rods 71 are moved so as to hold the plate 53 of the bearing 35 between the clamping heads 72 and one face of a support 73 pressed against the opposite face of the bearing 35. However, due to the inclination of the peripheral portion 64, the holding of the bearing 35 cannot be effectively ensured by the clamping heads 72.

In order to remedy this problem, the internal face 62 could comprise a plurality of flat clamping portions 76 extending in the plane P1 orthogonal to the axis X. The internal face 62 could thus comprise for example three clamping portions 76 spaced apart angularly between them regularly, or alternatively irregularly. The clamping portions 76 are advantageously located along the same circumference of the bearing 35.

As is better visible in FIG. 5, each clamping portion 76 extends at least partially between on the one hand an axial opening 50 for the passage of cooling air and on the other hand the external periphery of the plate 53.

Each clamping portion 76 is formed in a circumferential zone of the inclined peripheral portion 64. The maximum width of the clamping portions 76 measured in a radial direction is slightly less than the width of the inclined peripheral portion 64.

Each clamping portion 76 is delimited on one side partially by an edge of a corresponding axial opening 50 and on the other hand by a slope 77 situated on the opposite side with respect to the axial opening 50. The slope 77 advantageously has a shape in an arc. This ensures support of the clamping head 72 of the tool 70 while minimizing the surface of the clamping portion 76. Alternatively, the slope 77 may have another shape such as a triangle or rectangle shape.

In order to guarantee a precise angular positioning of the bearing 35 relative to the clamping tool 70, the bearing 35 includes indexing holes 80 intended to receive indexing studs 81 of corresponding shape carried by the clamping tool 70 , as shown in Figure 4.

In addition, the bearing 35 has central fixing holes 84 into which are inserted fixing members, such as screws, to ensure the mounting of the retaining plate (not shown) of the bearing inside the housing 38 corresponding.

As a variant, the inclined peripheral portion 64 does not extend over the entire circumference of the bearing 35, but only along a part of the circumference of the bearing 35. In all cases, the inclined peripheral portion 64 extends circumferentially at least between two adjacent fins 57 delimiting a lateral opening 51.

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.

Furthermore, 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. Rotating electric machine (10) for a motor vehicle comprising: - a stator (16) comprising a body (19) and a winding (18) provided with buns (20, 21) extending on either side of the stator body (19), - at least one bearing (35) comprising a plate (53) and a skirt (54), - the bearing (35) comprising an internal face (62) oriented towards a winding bun (20) and lateral openings (51) for the passage of cooling air, characterized in that the internal face (62) comprises a peripheral portion inclined (64) relative to a plane (P1) orthogonal to an axis (X) along which the stator (16) extends so as to increase a space (67) for the passage of cooling air between the winding bun (20) and the bearing (35). 2. Rotating electric machine according to claim 1, characterized in that the inclined peripheral portion (64) of the internal face (62) forms an angle (A) between 5 and 25 degrees relative to the plane (P1) orthogonal to the 'axis (X) along which extends the stator (16). 3. rotary electric machine according to claim 1 or 2, characterized in that the inclined peripheral portion (64) is arranged so that, in a plane passing through the axis (X) along which extends the stator (16) , the space (67) for cooling air passage increases in a radial direction away from the axis (X). 4. Rotating electric machine according to any one of claims 1 to 3, characterized in that the inclined peripheral portion (64) extends circumferentially at least between two adjacent fins (57) delimiting a lateral opening (51). 5 rotary electric machine according to claim 4, characterized in that the inclined peripheral portion (64) extends along a whole circumference of the bearing (35). 6. Rotating electric machine according to claim 4 or 5, characterized in that at least one fin (57) forms a rounded connection (65) between the inclined peripheral portion (64) and the skirt (54). 7. Rotating electric machine according to any one of claims 4 to 6, characterized in that the inclined peripheral portion (64) opens into a lateral opening (51). 8. rotary electric machine according to any one of claims 1 to 7, characterized in that the skirt (54) has at least one through hole (59) for the passage of a fixing member to maintain the bearing (35) resting against the stator body (19) or against another bearing (36). 9. rotary electric machine according to any one of claims 1 to 8, characterized in that the internal face (62) of the bearing (35) comprises a central annular portion (63) extending in a plane (P1) orthogonal to the axis (X) along which the stator (16) extends, the inclined peripheral portion (64) being located in the extension of the central annular portion (63). 10. rotary electrical machine according to any one of claims 1 to 9, characterized in that it comprises a rotor (12) and a fan (48) fixed on an axial end face of the rotor (12), a diameter external of the central annular portion (63) being substantially equal to an external diameter of the fan (48). 11. Rotating electric machine according to any one of claims 1 to 10, characterized in that the inclined peripheral portion (64) is arranged opposite the winding bun (20) towards which the internal face of the bearing (35).