EP1152153B1 - Fan for a motor vehicle having guide vanes - Google Patents

Abstract

The fan consists of a stator and rotor, which rotates relative to the stator, around an axis, to produce a flow of air in the direction of the axis. The rotor carries a series of blades (8), which extend, roughly radially, into the air flow. Various parameters of the rotor blade size, shape and orientation are defined within fixed limits.

Description

The invention relates to a motor vehicle fan as shown in DE-199 48 074, especially for cooling the drive motor, comprising a stator and a rotor capable of rotating relative to the stator about an axis so as to producing a flow of air in the direction of said axis, the rotor and the stator respectively having blades and guide vanes which extend substantially radially in said air flow, the guide vanes being located downstream of the blades with respect to this one.

The rotor or helix of an axial fan produces a substantially helical movement of the air, and the guide vanes have the function of straightening this movement to make it parallel to the axis and thus improve the aerodynamic efficiency of the fan.

The guide vanes used so far in automobile fans had an axial length, that is to say a dimension in the direction of the axis of rotation of the rotor, of the order of 20 mm, which was considered sufficient to ensure an efficient recovery of the airflow. Now, new means of analysis revealed that this was not the case, and that the known blades left a substantial circumferential component of the movement of the air flow.

The object of the invention is to optimize the geometric characteristics of the guide vanes so as to obtain an almost perfect recovery of the air flow.

The invention aims in particular a fan of the kind defined in the introduction, and provides that the axial length of the guide vanes is at least equal to 40 mm.

• La longueur axiale des aubes directrices est au plus égale à 60 mm. Au-delà de cette valeur, l'encombrement axial du stator augmente sans aucun bénéfice en ce qui concerne le rendement aérodynamique.
• L'angle aigu Ω entre la corde de la section transversale aplatie d'une aube et un plan radial est compris entre 25 et 35
• L'angle Ω décroît progressivement au moins sur les derniers 30 % de l'étendue radiale de l'aube.
• Les aubes ont une cambrure aérodynamique comprise entre 1,5 et 2,5.
• Les aubes sont réalisées d'une seule pièce avec un noyau central sensiblement annulaire à partir duquel elles s'étendent sensiblement radialement vers l'extérieur.
• Les aubes sont réalisées d'une seule pièce avec une bague périphérique annulaire à partir duquel elles s'étendent sensiblement radialement vers l'intérieur.
• Les aubes sont moulées en un matériau choisi parmi une matière plastique et/ou un matériau à base de magnésium.
• Le stator et le rotor ont un diamètre extérieur compris entre 200 et 500 mm.
• Le rotor est propre à tourner à une vitesse comprise entre 1500 et 4000 t/min.

Optional features of the invention, complementary or alternative, are set out below:

• The axial length of the guide vanes is at most equal to 60 mm. Beyond this value, the axial size of the stator increases without any benefit as regards the aerodynamic efficiency.
• The acute angle Ω between the rope of the flattened cross-section of a blade and a radial plane is between 25 and 35
• The angle Ω decreases progressively at least over the last 30% of the radial extent of the blade.
• The vanes have an aerodynamic camber between 1.5 and 2.5.
• The blades are made in one piece with a substantially annular central core from which they extend substantially radially outwardly.
• The blades are made in one piece with an annular peripheral ring from which they extend substantially radially inwards.
• The vanes are molded from a material selected from a plastic material and / or a magnesium material.
• The stator and the rotor have an outside diameter of between 200 and 500 mm.
• The rotor is able to rotate at a speed between 1500 and 4000 rpm.

The features and advantages of the invention will be set forth in more detail in the description below, with reference to the accompanying drawings.

Figure 1 is a perspective view of a fan according to the invention.

Figure 2 is a partial view of the stator in a radial direction, showing the flattened cross section of a guide vane.

The fan shown in FIG. 1, intended for cooling the drive motor of a motor vehicle, comprises a stator 1 and a rotor 2. The rotor 2 comprises a bowl-shaped hub 3 having a cylindrical wall of revolution 4, from which the propeller blades 5 extend substantially radially outwards, and a curved bottom 6. A cylindrical wall of revolution 7, preferably of the same diameter as the wall 4, is located axially facing thereof, opposite the bottom 6, and forms a central core for the stator 1, from which guide vanes 8 extend substantially radially outwards, substantially at the same radial height as the blades 5 The core 7 and the hub 3 are respectively integral with the stator and the rotor of an electric motor housed inside the core and the hub. In known manner, the radially outer ends of the blades 8 may be mutually connected by an annular peripheral ring not shown, the latter may further, as well as the core 7, be formed integrally with the blades, in particular by molding plastic material or a magnesium-based material.

FIG. 2 shows in part the core 7 of the stator, projected in a radial direction, as well as the flattened cross section of a guide vane 8, that is to say the plane closed curve obtained by cutting the blade by a cylindrical surface of revolution about the axis of the fan, and unrolling flat this cylindrical surface in the plane of the figure. This flattened cross section has an airfoil profile, the rope 10 is inclined at an acute angle Ω with respect to a radial plane such as that containing the downstream end 11 of the stator. The invention provides that the angle Ω, or wedging angle, is between 25 and 35 °, and decreases gradually when the cross-section away from the axis, at least over the last 30% of the radial expanse of dawn.

Figure 2 also shows the axial length L of the blade 8, which according to the invention is advantageously between 40 and 60 mm.

It also shows the distance h _max between the skeleton (or median line) 12 of the profile of the blade and the rope 10 of length ℓ.

K étant une constante empirique qui dépend de la géométrie et de l'aérodynamisme du stator.The aerodynamic camber is the camber C of the skeleton 12. It is calculated from h _max and ℓ by the following formula $$\mathrm{VS}\mathrm{=}\frac{{\mathrm{h}}_{\max }}{\mathrm{\ell }}\mathrm{\cdot }\mathrm{K}\mathrm{,}$$

K is an empirical constant that depends on the geometry and aerodynamics of the stator.

It has been found that the optimized values proposed by the invention are suitable for the whole range of outside diameters and rotational speeds used for automobile fans, that is to say from 200 to 500 mm and from 1500 to 4000 t / min.

Claims (10)

1. Fan for a motor vehicle, particularly for cooling the drive motor, comprising a stator (1) and a rotor (2) capable of rotating relative to the stator about an axis so as to produce an air flow in the direction of said axis, the rotor and the stator having respectively aerofoils (5) and guiding blades (8) that extend substantially radially in the said air flow, the guiding blades being situated downstream of the aerofoils relative to the latter, characterized in that the axial length (L) of the guiding blades is at least equal to 40 mm.
2. Fan according to Claim 1, in which the axial length (L) of the guiding blades (8) is at most equal to 60 mm.
3. Fan according to one of Claims 1 and 2, in which the acute angle Ω between the chord (10) of the flattened cross section of a blade and a radial plane (11) lies between 25 and 35º.
4. Fan according to Claim 3, in which the angle Q decreases progressively at least over the last 30% of the radial extent of the blade.
5. Fan according to one of the preceding claims, in which the blades (8) have an aerodynamic camber lying between 1.5 and 2.5, the aerodynamic camber being defined by the formula: $$C=\frac{h_{\max }}{l}\cdot K\mathrm{.}$$

   

   
   where h_max is the distance between the median line of the profile of the blade and the chord 1, K being an empirical constant that depends on the geometry and aerodynamism of the stator.
6. Fan according to one of the preceding claims, in which the blades (8) are made in a single piece with a substantially annular central core (7) from which they extend substantially radially outwards.
7. Fan according to one of the preceding claims, in which the blades are made in a single piece with an annular peripheral ring from which they extend substantially radially inwards.
8. Fan according to one of the preceding claims, in which the blades are moulded in a material chosen from a plastic and/or a magnesium-based material.
9. Fan according to one of the preceding claims, in which the stator (1) and the rotor (2) have an external diameter lying between 200 and 500 mm.
10. Fan according to one of the preceding claims, in which the rotor (2) is capable of rotating at a speed lying between 1500 and 4000 rpm.

Images