EP2821653B1 - Automotive fan nozzle with double-twisted arms - Google Patents

Description

The field of the present invention is that of the automobile, and more particularly that of the circulation of air for cooling equipment of the vehicle, including its engine.

The vehicles with heat engine need to evacuate the calories that generates their operation and are therefore equipped with heat exchangers, including cooling radiators, which are placed at the front of the vehicle and crossed by outside air. To force the circulation of this air through the exchanger or exchangers, a fan is placed upstream or downstream of them, upstream or downstream appreciating in this document with reference to the flow direction of the air. The propeller used to force air circulation is characterized by high flow and low pressure and has a very axial flow.

The fan, also referred to as a fan motor unit or GMV, generally comprises a nozzle or base, of parallelepipedal shape, which is traversed at its center by a hollow cylindrical cavity in which is positioned the propeller. This base ensures the attachment of the fan to a support, including the cooling radiator or the chassis, and the support of the electric motor for actuating the propeller and maintaining the axis around which it rotates. In addition, aerodynamically, it forms a wall and prevents recirculation between the upstream and downstream of the propeller.

The attachment of the electric motor to the base can be constituted by several simple arms when one seeks to give it a function of mechanical strength or by the arms in the form of aircraft wing, or blade stators , when we try to give them also an aerodynamic function. The stator vanes are known in the field of turbomachines where their effectiveness is demonstrated when the fluid gyration is important, which allows a significant recovery of the flow.

• assurer la liaison mécanique entre l'anneau porteur du moteur et la buse, en présentant un encombrement réduit et une rigidité structurelle permettant d'éviter les déformations selon les différents types de conditions de fonctionnement du véhicule.
• contribuer à la performance aérodynamique de l'ensemble, en minimisant les pertes par frottement fluide grâce à un bon profilage et éventuellement en redressant l'écoulement hélicoïdal en sortie d'hélice pour récupérer l'énergie contenue dans la composante tangentielle de vitesse.

The arms of the motor-fan units are conventionally obtained by molding, and must meet two types of requirements:

• ensure the mechanical connection between the motor carrier ring and the nozzle, with a reduced overall size and structural rigidity to prevent deformation under different types of vehicle operating conditions.
• contribute to the aerodynamic performance of the assembly, by minimizing fluid friction losses through good profiling and possibly by straightening the helical flow at the helix outlet to recover the energy contained in the tangential component of speed.

The solutions used are usually simple arms, of generally square or rectangular sections, which have excellent rigidity and whose number is limited because of their high aerodynamic resistance.

It is also possible to use so-called "stator" arms, which have a smaller thickness, and whose section has an aerodynamic profile responsible for straightening the flow. Their aerodynamic resistance is weaker unitarily but their rectifier function and lower stiffness generally require them to be used in greater numbers, to the detriment of increasing overall aerodynamic resistance. They are of little use aerodynamically, and therefore little used when placed downstream of a vehicle fan propeller, which is weakly aerodynamically loaded and generates a low gyration.

The document US 2006/147304 A1 discloses a fan support device according to the preamble of claim 1.

On the other hand, whatever the solution adopted, it is known that the stator arms or vanes contribute to the generation of noise, according to different mechanisms that produce either tonal noise at particular frequencies or broadband noise over the entire range. frequency. The fundamental frequency and its harmonics are excited by periodic phenomena, such as the successive passages of blades of the propeller in front of the stator arms. Acoustic sources come from fluctuations in air density produced by instationnarities of flow, and it is observed that a propeller mounted on its base produces more noise, especially for the tonal contribution.

It is therefore necessary to seek to improve the acoustic performance of the front fans of motor vehicles, while trying to reduce aerodynamic losses and increase the efficiency of the propellers.

The present invention thus aims to provide an arrangement for an automobile fan that improves the performance of it compared to models currently in use.

For this purpose, the subject of the invention is a device for supporting a fan for cooling a fluid flowing through a cooling circuit of a motor vehicle, said device comprising an armature provided with an orifice intended to receive a propeller rotated about an axis of rotation to generate a ventilation flow, an actuator motor support of said propeller and a plurality of holding arms extending across said port for connecting said carrier to said propeller frame.

The section profile of said holding arms in a tangential plane has a variable pitch between their blade root, located at said support, and their blade head, located at their attachment to said frame.

The choice of an evolutionary setting makes it possible to orient the profile of the arm according to the local orientation of the air flow and thus to very significantly reduce the instationnarities, and thus the radiated noise.

The main feature of the invention is that the wedging of said arms moves in a first direction between said blade root and a first point located on the span of the holding arm, and in an opposite direction between a second point, located radially beyond said first point on the span of said holding arm, and said blade head, the profile of said holding arm being oriented substantially in a radial plane at its foot, the profile of said holding arm at the level of its foot having a setting angle greater than 70 ° with respect to the axis of rotation of said propeller.

Preferably, said first point and said second point coincide. This configuration provides the best possible reduction for the radiated noise, in particular by helping to open the flow passage section in the central part of the arms.

Advantageously, said first and second points are located between the first and third quarter of the span of said holding arm.

In a preferred embodiment the profile of said holding arm is oriented substantially in a radial plane at its head.

More preferably the profile of said holding arm at its head has a setting angle greater than 70 ° relative to the axis of rotation of said helix.

In one mode, the profile of said holding arm at the point or points of change of the direction of evolution of the wedging, that is to say, of said first point or points mentioned above, has a calibration angle lower than 20 ° with respect to the axis of rotation of said propeller.

According to one aspect of the invention, the section profile of said holding arms in a tangential plane is aerodynamic type.

A ratio of a length I of a chord of the profile of said holding arms in a tangential plane to a thickness e of said profile is advantageously greater than or equal to 1.5, in particular at the thickest point of said profile.

The invention also relates to a motor-fan unit for cooling a fluid flowing through a cooling circuit of a motor vehicle comprising a propeller rotated about an axis of rotation to generate a ventilation flow and an engine. actuating said propeller characterized in that said motor and said propeller are carried by a support device as described above.

Preferably, the support arms of the support device are positioned at a distance from the blades of the propeller. The spacing left between the stator vanes and the vane blades, beyond the distance strictly necessary to avoid mechanical interferences in operation, avoids interactions between the rotor and the stator which are generating noise.

The invention finally relates to a cooling module for a front end of a motor vehicle comprising a motor-fan unit as described above.

The invention will be better understood, and other objects, details, features and advantages thereof will become more clearly apparent in the explanatory description. The following detailed description of an embodiment of the invention given by way of purely illustrative and non-limiting example, with reference to the accompanying schematic drawings.

• la figure 1 est une vue simplifiée et schématique d'un module de refroidissement d'un bloc moteur d'un véhicule automobile ;
• la figure 2 est une vue éclatée, en perspective, d'un module de refroidissement de véhicule automobile ;
• la figure 3 est une vue en perspective d'un groupe moto-ventilateur pour moteur d'automobile, muni de bras simples de maintien de l'hélice ;
• la figure 4 est une vue en perspective d'un groupe moto-ventilateur pour moteur d'automobile, muni de bras statoriques selon l'invention ;
• la figure 5 est une vue de détail en perspective du stator de la figure 4,
• la figure 6 est une vue de détail en perspective d'un bras du stator de la figure 4,
• la figure 7 est une vue d'un profil, selon un plan tangentiel, d'un bras de maintien d'un dispositif selon l'invention.

On these drawings:

• the figure 1 is a simplified and schematic view of a cooling module of an engine block of a motor vehicle;
• the figure 2 is an exploded view, in perspective, of a motor vehicle cooling module;
• the figure 3 is a perspective view of a motor-blower unit for an automobile engine, provided with simple propeller holding arms;
• the figure 4 is a perspective view of a motorcycle fan assembly for an automobile engine, provided with stator arms according to the invention;
• the figure 5 is a detailed perspective view of the stator of the figure 4 ,
• the figure 6 is a detailed perspective view of a stator arm of the figure 4 ,
• the figure 7 is a view of a profile, in a tangential plane, of a holding arm of a device according to the invention.

Referring to the figure 1 , we see a cooling module 3 of a motor block 5 of a motor vehicle. It comprises in particular a propeller 1 of a motor-fan unit and a heat exchanger 7 such as a cooling radiator. The propeller 1, positioned here between the cooling radiator 7 and the engine block 5, can be arranged either in front or behind the radiator 7. These elements 1, 5 and 7 are substantially axially aligned. In the remainder of the description, the axial, radial or tangential terms are understood with reference to the axis of rotation of the helix 1.

The propeller 1 is rotated about an axis A. When the propeller 1 is rotated, for example by an electric motor (not shown), the propeller 1 sucks the air and causes it to through the radiator. The flow of air flows in a direction of flow oriented substantially from the radiator 7 to the engine block 5.

The figure 2 shows, in perspective, the various components of a cooling module. The fan, which is here placed downstream of the radiator 7, is shown in exploded view: it comprises firstly a base, or armature or nozzle 2, which ensures, in addition to its function of capturing air and guiding towards the propeller 1, a mechanical support function for all the elements of the fan. The nozzle has a shape rectangular extending radially parallel to the radiator. It is placed in frontal barrier of the air which crosses this last one. It has in its center, a hole or axial cylindrical cutout 21 to let the ventilation air. The fan also comprises a propeller 1 which is disposed inside this axial cut and which rotates under the action of the electric motor 6, positioned in a central hub 9 of said propeller. It finally comprises radial arms 4 which are attached to the periphery of the cylindrical cutout 21 of the nozzle 2 and which carry, via a ring or central cover, the electric motor 6 which drives the propeller.

The propeller 1 comprises a plurality of movable blades 11 which extend radially from the hub 9 towards the inner wall of the cutout 21 made in the nozzle 2. In the configuration shown, without it being obligatory, it comprises at its end external radial shell 8 on which are attached the heads of the movable blades 11, so as to reduce the risk of floating thereof.

The figure 3 shows in more detail a fan of the prior art, comprising a propeller 1 having movable blades 11. Said propeller is carried by the electric motor 6 which is itself carried by the base 2 by means of arms. On the base 2, downstream of the propeller 1, are fixed radial arms 4 which are regularly arranged on the circumference of the cutout which is formed in the base 2 to allow passage to the flow of ventilation. These arms are simple arms which are oriented radially and which have a symmetry with respect to the radial plane in which they extend. The presence of these arms generates a drag due to the friction of the air. In the present case they are not directed in the direction of the flow which has a helical shape, and they disturb the tangential component of the flow. The arms 4 are fixed on the peripheral side on the frame of the base 2 of the fan and meet centrally on the central fixed cover 16. Inside this cover are fixed bearings (not visible in the figure) which are carriers of the axis of rotation of the hub 9 of the propeller. The propeller 1 is thus able to move in rotation within the cut made in the base 2, in the direction indicated by the arrow Ω of the figure, under the action of the electric motor 6 which is positioned in the central bonnet 16.

The figure 4 shows an improved fan according to the invention. It is similar to that of the figure 2 for the elements which bear the same reference, with the exception of the support arms of the central cover 16. The simple arms 4 of the figure 2 are replaced by arms profiles, or stators 14, having a dual aerodynamic and acoustic function. Instead of the arms in the form of flat plates oriented in the direction of the flow that passes through the helix, the stators 14 are constituted by thin blades, of large span and elongated section, with a rope whose length l is greater at least 1.5 times that of its thickness e ( figure 7 ), in particular at its point of greatest thickness. These stator blades have an aerodynamic profile to reduce their drag, and the wedging α ( figure 7 ) of the profile evolves throughout its span, between its foot 14a carried by the central cover 16 and its head 14b carried here by a plate 12 which extends axially from the base 2. This plate 12 is intended to attach the stators 14 away from the base 2 and the mobile blades 11 of the fan.

In a more visible way with reference to Figures 5 and 6 , the wedging of the section profile of a said stator 14 along a tangential plane evolves along their span, starting from a substantially radial orientation at its foot 14a and the central cover 16, to come to a clearly more axial mid-span of the stator, and to return to a substantially radial orientation at its head 14b and the wafer 12.

The law of the setting of the stator sections, that is to say of the angle α that makes the rope of this section with the axial direction, is evolutive along the span to adapt to the direction and the gyration of the flow at the exit of the helix; this is beneficial both for the aerodynamic efficiency and for the reduction of the instabilities that are generating noise. Preferably, the foot wedging, as well as the head wedging, must have a significant value (typically greater than 70 °), while the central portion of the blade, that is, included in 25 and 75% of the span. , must have a clearly low setting (typically less than 20 °). The stator thus has a doubly twisted shape along a line connecting the mid-chord points of the stator, the twisting being constituted by a rotation of the stator section, in a tangential plane, when this line is described since foot to the head of the stator. It is said doubly twisted because twisting according to the invention preferentially increases from the foot to mid-span, to decrease from mid-span to the head and back to a weakly twisted level.

According to a non-illustrated embodiment, the evolution of the setting could be interrupted, or follow another law, in the central part of the stator.

As a result of the substantially radial orientation of the profile at the bottom as well as at the top, a very good compactness of the solution, which makes it possible to free axially space for the engine compartment, or, more usefully on the acoustic plane, to place the holding arms away from the moving blades, that is to say at a distance greater than that which would be strictly necessary to take into account the relative axial positioning variations in operation and to avoid possible mechanical interference.

With this twisting the arms are better suited than flat plates both aerodynamically and acoustically. The reduction of the instationnarities created by the arms thus allows an improvement of the acoustics, by minimizing the rotor-stator interactions and by reducing the noise generated by the stator itself. In addition, the increase in the distance between the rotor and the stator, made possible by the greater compactness of the motor-fan unit, will reduce the interaction between the rotor and the stator and therefore contribute to a greater reduction. the acoustic level of this group.

Another benefit of twisted stator blades is improved performance at the point of operation, with increased efficiency for the proposed solution compared to the propeller alone. Comparisons were made and it follows that the torque required to drive the propeller is slightly decreased while the pressure performance remains at its nominal point, hence this gain in performance.

Claims (11)

1. Device for supporting a fan for cooling a fluid flowing around a cooling circuit of a motor vehicle, the said device comprising a frame (2) provided with an orifice intended to receive a blower wheel (1) rotationally driven around an axis of rotation so as to generate a ventilation flow, a support housing (16) for a drive motor (6) for the said blower wheel, and a plurality of support arms (14) extending across the said orifice so as to connect the said support housing to the said frame, the cross-sectional profile of the said support arms along a tangential plane having a pitch angle variable between the blade bottom end (14a) of said arms, situated in the region of the said support housing (16), and the blade top end (14b) of said arms, situated at the point where they are attached to the said frame, the pitch angle of the said arms (14) progressing in a first direction between the said blade bottom end and a first point situated on the span of the said support arm and, in an opposite direction, between a second point situated radially beyond the said first point on the span of the said support arm and the said blade top end, called change-over points for the direction of progression of the pitch angle, the said supporting device being characterized in that the profile of the support arm (14) is oriented substantially along a radial plane at its bottom end (14a), the profile of the support arm (14) at its bottom end (14a) having a pitch angle greater than 70° relative to the axis of rotation of the said blower wheel.
2. Device according to Claim 1, wherein the said first point and the said second point are merged together.
3. Device according to either one of Claims 1 or 2, wherein the said first point and/or second point are situated between the first quarter and the third quarter of the span of the said support arm.
4. Device according to one of Claims 1 to 3, wherein the profile of the support arm (14) is oriented substantially along a radial plane at its top end (14b) .
5. Device according to any one of Claims 1 to 4, wherein the profile of the support arm (14) at its top end (14b) has a pitch angle greater than 70° relative to the axis of rotation of the said blower wheel.
6. Device according to one of Claims 1 to 5, wherein the profile of the support arm (14) at the change-over point or points for the direction of progression of the pitch angle has a pitch angle of less than 20° relative to the axis of rotation of the said blower wheel.
7. Device according to any one of the preceding claims, wherein the cross-sectional profile of the said support arms (14) along a tangential plane is of the aerodynamic type.
8. Device according to any one of the preceding claims, wherein a length "1" of a chord of the profile of the said support arms (14) along a tangential plane is greater than or equal to 1.5 times a thickness "e" of the said profile at the thickest point of the said profile.
9. Engine fan for cooling a fluid flowing around a cooling circuit of a motor vehicle comprising a blower wheel (1) rotationally driven around an axis of rotation so as to generate a ventilation flow, and a drive motor (6) for the said blower wheel, characterized in that the said motor and the said blower wheel are mounted on a supporting device according to any one of the preceding claims.
10. Engine fan according to the preceding claim, wherein the support arms (14) of the supporting device are positioned at a distance from blades (11) of the blower wheel (1).
11. Cooling module for a front side of a motor vehicle comprising an engine fan according to either one of Claims 9 and 10.

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