FR2660123A1 - ALTERNATOR WITH PERMANENT MAGNET ROTOR, PARTICULARLY FOR MOTOR VEHICLE. - Google Patents

Abstract

Alternator, in particular for a motor vehicle, comprising a housing (11) in which are arranged a stator assembly (12) and a rotor assembly (13), the rotor assembly (13) comprising a central hub (20) made integral in rotation d 'a drive shaft (14), said central hub (20) being connected by legs (23) to a circular rim (22) at the outer periphery of which are disposed permanent magnets (27) on a ring (26) ), characterized in that the rotor (13) constitutes axial ventilation means and radial ventilation means.

Description

The present invention relates generally to alternators,

  in particular for motor vehicles and more particularly alternators in which the magnetic excitation flux is produced by permanent magnets mounted in the rotor. This particular type of alternator has many advantages Indeed, although their stator is of conventional shape, their general structure is simplified and they have a great robustness of

operation.

  In addition, for an identical delivered power, their axial size is much smaller than that of a conventional alternator, which facilitates their

installation in the engine hood.

  However, such devices need to be cooled during operation so that they remain at a limited temperature allowing them

to ensure optimal performance.

  This cooling is generally obtained by forced ventilation through the device to be cooled at

by means of a fan wheel.

  This fan wheel is generally placed outside the device, sometimes inside the casing in which the electrical assembly of the

the alternator.

  In all cases, the presence of such a fan wheel increases the axial size of the entire alternator in such a way that it can cancel out the advantages inherent in use.

permanent magnets.

  The present invention solves these problems, and proposes for this purpose an alternator, in particular for motor vehicles, comprising a casing in which are arranged a stator assembly and a rotor assembly, the rotor assembly comprising a central hub made integral in rotation with a drive shaft, said central hub being connected by legs to a circular rim at the outer periphery of which are arranged permanent magnets on a crown, characterized in that the rotor constitutes means of axial ventilation and means of radial ventilation . The axial ventilation means consist of the legs which have an oblong section, called an airplane wing, the axis of which is inclined relative to the horizontal and thus form blades of

ventilation.

  The radial ventilation means consist of blades formed of material at the periphery of the rim

rotor rotor.

  Thus, the rotor according to the invention comprises all the ventilation means necessary for optimum efficiency of an alternator of the aforementioned type without increasing

its axial size.

  The following description next to

  accompanying drawings will better understand how the invention

can be done.

  Figure 1 is a sectional view of an alternator equipped according to the invention; Figure 2 is a view of a rotor

  alternator according to arrow F in Figure 1.

  The alternator shown in section in FIG. 1 comprises a casing 11 produced in a conventional manner by molding, a stator 12 and a rotor 13 rotating at

inside the stator.

  In a manner known per se, the rotor assembly 13 is made integral with a shaft 14 and the assembly thus formed is supported by bearings 15, 16 mounted in

the housing 11.

  The shaft 14 protrudes from the bearing 16 and from the casing 11, so as to be able to receive at its end a pulley 17 which, by means of a belt constitutes the coupling to a motor device such as

  the internal combustion engine of a motor vehicle.

  The casing 11 supports a stator 12 which can be of a conventional laminated construction 18 with an armature winding housed in notches and whose

  exterior parts are shown in 19.

  As shown in FIG. 2, the rotor 13 is in the general form of a wheel produced by

  molding in material such as aluminum.

  The rotor 13 has a central hub 20, in which a cylindrical bore 21 is formed through

  from which the rotor 13 is fitted on the shaft 14.

  The hub 20 of the rotor 13 is connected to a rim

  circular 22 by means of jambs 23.

  These legs 23, eight in number in the example shown are distributed angularly, so

  uniform and their axes are radial.

  According to one aspect of the invention, said legs 23 constitute the means of axial ventilation

of the alternator.

  To this end, as illustrated in particular in 24 in FIG. 1, their section is generally oblong in shape, called an airplane wing, and

  inclined to a horizontal plane.

  As can be seen, the inclination of the upper jamb is reversed with respect to that of the lower jamb. These particular provisions mean that the legs 23 constitute, in a way, the blades of a ventilator which sucks in the outside air by

  ventilation 30 provided in the housing 11.

  The circular rim 22 has over its entire outer periphery a recess 25 intended to receive a crown 26 made of steel and fixed to the rim

  circular 22 for example, by riveting.

  On the outer surface of this ring 26 are arranged permanent magnets 27 to establish the necessary excitation flux The axes of these magnets, parallel to the axis of rotation of the rotor, are uniformly distributed around the axis 13. The faces polar successive permanent magnets 27 are alternately of opposite poles, in other words a north polar face is framed by the

  south polar faces of two neighboring magnets.

  According to another aspect of the invention, the rotor 13 also includes radial ventilation means intended to cool the ends in particular.

  19 of the armature winding of the stator 12.

  These means consist of blades 28 formed of material over the entire periphery of the circular rim 22

  and located to the right of said outer ends 19.

  These vanes 28, of which there are eighteen in the example shown, have a generally rectangular cross section as illustrated at 29 in FIG. 1 and are angularly distributed uniformly or not.

on the circular rim 22.

  It will be noted in FIG. 2 that, advantageously, the vanes 28 are not radial, the axis of their section having an inclination relative to the

ray passing through its center.

  This arrangement increases the effect of stirring the air and therefore improves the cooling of the entire stator 12, the air flowing between the louvers 30 and the openings 31 provided in the casing 11 in line with the outer ends 19 of the armature winding. Thus all the cooling means necessary for good efficiency of the alternator assembly are entirely incorporated into the rotor 13, which makes it possible to produce the assembly of such a machine in a

minimum axial dimensions.

Claims (5)

  1) Alternator, in particular for a motor vehicle, comprising a casing (11) in which are arranged a stator assembly (12) and a rotor assembly (13), the rotor assembly (13) comprising a central hub (20) made integral with rotation of a drive shaft (14), said central hub (20) being connected by legs (23) to a circular rim (22) at the outer periphery of which are arranged permanent magnets (27) on a crown (26), characterized in that the rotor (13) constitutes axial ventilation means and radial ventilation means. 2) Alternator according to claim 1, characterized in that the axial ventilation means   consist of the legs (23).   3) Alternator according to claim 2, characterized in that each of the legs (23) has a section (24) of generally oblong shape, called wing   plane, inclined to the horizontal.   4) Alternator according to claim 1, characterized in that the radial ventilation means are constituted by blades (28) located at the   periphery of the circular rim (22).   ) Alternator according to claim 4, characterized in that the vanes (28) are provided with   material at the periphery of the circular rim (22).   6) Alternator according to one of claims   4,5, characterized in that the blades (28) have a section (29) of generally rectangular shape whose axis has an inclination relative to the radius passing through their center.   7) Alternator according to one of claims 4,5   characterized in that the vanes (28) are placed in line with the ends (19) of the stator armature winding (12).