EP1532721A2

EP1532721A2 - Internal ventilating system for a rotating electrical machine such as a motor vehicle alternator

Info

Publication number: EP1532721A2
Application number: EP03748192A
Authority: EP
Inventors: Claudiu Vasilescu
Original assignee: Valeo Equipements Electriques Moteur SAS
Current assignee: Valeo Equipements Electriques Moteur SAS
Priority date: 2002-06-28
Filing date: 2003-06-30
Publication date: 2005-05-25
Also published as: FR2841705A1; WO2004004096A3; US20060012253A1; JP2005532019A; WO2004004096A2; US7138735B2; FR2841705B1

Abstract

The invention concerns a rotating electrical machine, comprising inside a housing, a fixedly mounted stator and a rotor rotatably mounted in the stator, the ventilating system including in particular at least one ventilator integral with the rotor and capable of generating a cooling air stream inside the housing, radial air intake orifices (20) arranged in the housing, and cooling air discharge ports (22) arranged in said housing in a ring opposite the periphery of the ventilator and mutually separated by fins (24) stiffening the housing in the port region. The system is characterized in that the angle of inclination of the fins (24) relative to the tangent perpendicular to the radial direction (R) ranges between 38° and 52°. The invention is for use for motor vehicle alternators.

Description

"Internal ventilation system of a rotating electrical machine such as an alternator, in particular of a motor vehicle".

TECHNICAL FIELD OF THE INVENTION The invention relates to an internal ventilation system of a rotary electric machine of the type comprising, inside a carcass, a stator mounted fixed in the latter and a rotor mounted rotatably in the stator, the ventilation system comprising in particular at least one fan integral with the rotor and capable of creating a flow of cooling air inside the carcass, axial air intake openings made in the carcass and air inlets cooling air discharge, formed in said carcass in a ring facing the periphery of the fan and separated from each other by stiffening fins of the carcass in the area of the gills. The invention also relates to a rotary electric machine comprising such a ventilation system.

State of the art

It has been found that to minimize the pressure losses caused by the fins and the noise due to the detachments of the cooling fluid, here air, it is advantageous to tilt them according to the direction of the air flow. to be evacuated. The obligation of the ventilator-carcass association constitutes a very troublesome constraint.

OBJECT OF THE INVENTION The object of the present invention is to propose a ventilation system of the type indicated above, which overcomes this drawback.

To achieve this goal, the ventilation system according to the invention is characterized in that the angle inclination of the fins relative to the tangent is between 38 ° and 52 °.

It has surprisingly been found that such a range of angles is suitable for a large number of fan-carcass combinations, while ensuring low pressure losses and noise reduction. Thus, for each fan-carcass combination, the angle of inclination is calculated and a range is proposed.

According to a characteristic of the invention, it is advantageous to choose the angle at a value of 45 °.

Brief description of the figures

The invention will be better understood, and other objects, characteristics, details and advantages thereof will appear more clearly in the explanatory description which follows, made with reference to the appended schematic drawings given solely by way of example illustrating a method of realization of the invention and in which:

- Figure 1 is an axial sectional view of an alternator according to the state of the art;

- Figure 2 is a simplified schematic view of a ventilation system according to the invention, showing a fan and vents for evacuation of cooling air. FIG. 3 is a perspective view of a front bearing provided with ventilation openings according to the invention, and

- Figure 4 illustrates another advantageous characteristic of the ventilation system according to the invention. - Figure 5 is a radial view of the interior of a stator developed flat.

Description of preferred embodiments of the invention.

Referring to Figure 1 we will first describe the general structure of a ventilation system for a rotating electric machine, in the present case of an alternator for a motor vehicle, to place the invention in context. This type of alternator is described for example in document FR-A-2 602 925 to which reference will be made for more details.

_In this figure, the reference 1 designates an openwork alternator carcass of general shape of revolution which coaxially surrounds a stator 4 provided with windings 5 inside which is rotatably mounted a rotor 6 of the claw type comprising a shaft 7 supported by the carcass by means of front 9 and rear bearings 10. The rotor consists of two pole pieces respectively front 12 and rear 13 and a winding 14. Each pole piece 12, 13 carries on its part forming a plate a fan respectively front 15 and rear 16. The fans are integral in rotation with their respective carrier pole piece. The stator 4 is carried internally by the carcass 1. As shown diagrammatically in the figure, each fan carries on its external free face a plurality of ventilation blades 18.

The carcass 1 is formed by two hollow parts called respectively front bearing 19 and rear bearing 21.

These bearings are assembled together for example using screws 26 and each comprise a generally transversely oriented part connected by one through a connection zone to an axially oriented crown. The bearings centrally support the bearings 9, 10 in their transverse part, knowing that the front bearing is adjacent to the alternator drive pulley and the rear bearing to the rectifier bridge (not referenced) which the alternator comprises .

The transverse parts of the bearings are provided with axial air intake orifices 20. The crown of the bearings extends at the outer periphery thereof and internally carries the stator 4, more precisely the body which the latter has for carrying the windings 5. This ring is provided with openings 22 called gills. The louvers 22 are axially oblong in shape and also affect the external periphery of the transverse part of the bearing concerned. The vents 22 extend on either side of the body of the stator 4 and are located outside of the projecting parts, called chignons, windings 5 and fans. The louvers 22 therefore comprise an axial orientation part, called the axial opening, affecting only the crown of the bearing.

The axial openings have an axial length equal to the height of a cylindrical portion of the crown defined by a first circle corresponding to the bottom of the openings adjacent to the stator body and by another circle corresponding to the edge of the axial openings of the openings. FIG. 3 shows in perspective the openings 22 delimited by fins 24.

The fans are configured to create a flow of cooling air, the components of which are indicated by arrow lines, by drawing in ambient air through axial intake ports 20. A portion of the cooling air indicated by arrow F is evacuated through vents 22.

The invention relates to the internal ventilation system essentially comprising a fan 15 or 16 and the vents 22 for evacuating the air flow created by the fan and illustrated by the arrow F.

The invention will be described below with reference to FIGS. 2 and 3. In these figures, the fan is designated as in FIG. 1 by the reference 16, the fan blades by the reference 18 and the ventilation openings carry the reference 22.

As can be seen in FIG. 3, in which the part of the carcass which is provided with the gills 22 is a front bearing, the openings 22 are obtained by providing in the appropriate openings made in the peripheral face of the bearing of the fins 24 which extend parallel to the axis of the alternator and are inclined at a predetermined angle relative to the direction radial R. The fins 24 have the function of mechanically stiffening the bearing.

According to the invention, the fins 24 have an angle of inclination relative to the tangent perpendicular to the radial direction, between 38 ° and 52 °, preferably 45 °. In other words the angle of inclination with respect to the radial direction R is between (90 ° -38 °) and (90 ° -52 °)

Despite the general opinion that the fins should have an inclination substantially parallel to the direction of flow of the cooling air to be discharged through the vents, for each fan / carcass or bearing combination, to avoid significant pressure losses, it has been found that when choosing inclinations in the above-mentioned value range from 38 ° to 52 °, good fan / bearing compatibility is preserved in a large number of such fan / bearing combinations, with relatively low pressure losses and reduced air separation. The ventilation system is therefore quieter.

Regarding the production of the openings 22 and the fins separating them, it should be noted that the radial opening factor of the openings must advantageously be at least 40% insofar as an increase in the radial opening surface increases, so significant, the cooling efficiency of the fans, namely in particular the electronic components at the rear bearing of the alternator and the windings.

To increase the performance of the ventilation system, the circumferential size of the axial openings of the openings 22 so that the surface of the axial openings represents at least 40% of the surface of the above-mentioned cylindrical portion of the crown. Figure 4 illustrates another measure to optimize the cooling of the alternator. Indeed, this figure illustrates that the fan blades should not overlap by more than a third, namely the distance 1 of their length of rope L the axial openings as indicated at 20 in Figure 1 of the carcass or front and rear bearings. In other words, the outside diameter of the axial openings must be chosen according to the inside and outside diameters of the fan. Advantageously, to obtain optimized ventilation, the distribution of the fins can be carried out so that they are angularly distant by a distance D = F.360 ° / N

or N = number of stator notches

F is a multiplying coefficient which is determined according to the mechanical configuration of the electric machine, by iterative calculation.

So, for example,

if N = 36 notches, then 1.360 ° / 36 = 10 °. The fins are therefore angularly distant by 10 ° or a multiple of 10 °.

if N = 48 notches, then 2.360 ° / 48 = 15 °. The fins are therefore angularly distant by 7.5 ° or a multiple of 7.5 °.

if N = 96 notches, then 3.360 ° / 96 = 11.25 °. The fins are therefore angularly distant from 3.75 ° or a multiple of 3.75 °. _T hus, as shown in Figure 5, this configuration allows to obtain an optimized ventilation thanks to a reduction in losses of load to the coil ends of the coil 5 wound in the grooves 32 of the stator 4.

Indeed, the winding density of the front buns

30 and rear 31 (partially shown in the figure

5 for reasons of clarity) which protrude axially from the stator 4 have a maximum density in line with the grooves 32 and constitute an obstacle for the evacuation of air by the radial vents 22. Thus, according to the invention, the fins 24 are arranged so as to angularly coincide with these areas of high winding density and thus do not create additional obstacles in front of the air passages 34 in line with the teeth 33 of the stator. To this end, the fins 24 are therefore radially aligned with the grooves 32 of the stator.

Advantageously, the fins are radially aligned on only part of the set of grooves 32 of the stator. The pitch of the fins can be a multiple of the pitch of the grooves / teeth of the stator.

According to another embodiment, the fins can radially superimpose the grooves 32 of the stator in a random pitch 35.

Advantageously, at least 70% of the fins are radially aligned with the grooves of the stator.

Claims

1. Internal ventilation system of a rotary electrical machine such as an alternator, in particular of a motor vehicle, of the type comprising, inside a carcass, a stator mounted fixed in the latter and a rotor mounted rotatably in the stator , the ventilation system comprising in particular at least one fan integral with the rotor and capable of creating a flow of cooling air inside the carcass, axial openings (20) for admission of air formed in the carcass, and cooling air discharge openings, formed in said carcass in a ring facing the periphery of the fan and separated from each other by fins (24) for stiffening the carcass in the area of the radial openings ⁽ 22), characterized in that the angle of inclination of the fins (24) relative to the tangent perpendicular to the radial direction (R) is between 38 ° and 52 ° and in that the gills ra dials (22) have an axial orientation part, called an axial opening, which affects only the axial orientation ring axially and which belongs to a cylindrical portion and in that the surface of the axial openings represents at least 40% of the surface of the cylindrical part.

2. Ventilation system according to claim 1, characterized in that the angle of inclination of the stiffening fins (24) is of the order of 45 °.

³ . Ventilation system according to one of claims 1 to 2, characterized in that the angular distance between the radial air discharge fins (24) is equal to F.360 ° / N or N corresponds to the number notches on the stator and F is a multiplier.

4. Ventilation system according to the preceding claim characterized in that in that the fins

(24) are radially aligned with the grooves (32) of the stator.

5. Ventilation system according to claim 3 characterized in that in that at least 70% of the fins

(24) are radially aligned with the grooves (32) of the stator.

6. Ventilation system according to claim 3 characterized in that in that the pitch of the fins (24) is a multiple of the pitch of the grooves (32) of the stator.

7. Ventilation system according to claim 1, characterized in that the part of the length of rope (L) of the blades (18) of a fan (16), overlapping the axial openings (20) of the carcass must be equal or less than a third.

8. Rotating electric machine, such as an alternator, in particular for a motor vehicle, characterized in that it comprises a ventilation system according to one of claims 1 to 7.