Wheel rim for a vehicle

A wheel rim having a central axis and comprising a central hub configured to be fixed to a suspension of a vehicle; a peripheral ring, which is arranged around the hub with a predetermined radial distance from the hub itself and is configured to receive a tire of the vehicle on a radially outermost surface thereof; a plurality of spokes equally spaced angularly from one another around the axis and connecting the peripheral ring to the hub; and at least one projection protruding in a cantilever fashion towards the hub, starting from a radially innermost surface of the peripheral ring, opposite to the radially outermost surface, and defining an airfoil configured to generate, in use, during the forward travel of the vehicle, a channelling of the air towards the outside of the wheel rim.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application no. 102018000010194 filed on Nov. 9, 2018, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE ART

The present invention relates to a wheel rim for a vehicle, in particular for a motor-vehicle, preferably for a motor-vehicle of the high-performance type, to which the following description will make explicit reference without thereby losing in generality.

PRIOR ART

As is known, a wheel rim is the part of the wheel, which connects the tire to the vehicle. In particular, the wheel rim and the tire thereof are normally housed in special compartments of the bodywork of the vehicle, called “wheel compartments” and delimited by arch-shaped bodywork parts known as “wheel arches”. Wheel rims of the known type have a central axis and generally comprise:a central hub configured to be fixed to a suspension of the vehicle;a peripheral ring, which is arranged around the central hub with a predetermined radial distance from the hub itself and onto which the tire is directly mounted; anda series of spokes equally spaced angularly from one another around the axis of the wheel rim, extending radially and connecting the peripheral ring to the central hub.

A wheel rim should be as light as possible, since it constitutes a non-suspended mass of the vehicle; thus, the wheel rim contributes to increasing the overall non-suspended mass, consequently increasing the inertia of the suspensions; basically, if the wheel rims are too heavy, the suspensions must manage greater weights and they are thus less reactive, with a consequent increase in the difficult of maintaining an optimum road grip, especially in the case of a high-performance motor-vehicle.

It should also be noted that an increase in the mass of the wheel rim determines a corresponding increase in the rotational inertia, which increases the resistance of the wheel to change the direction thereof, with effects on the responsiveness of the steering.

Another very important aspect, which must be considered in the design of a wheel rim, is the effect it has on the aerodynamics of the vehicle.

As is known, in high-performance motor-vehicles, the aerodynamics are studied to generate an elevated aerodynamic downforce (or rather an elevated aerodynamic thrust downwards) simultaneously trying to minimise the aerodynamic resistance on advancing. Consequently, the aerodynamic efficiency of a motor-vehicle is assessed according to the ratio between the aerodynamic downforce and the corresponding aerodynamic resistance on advancing: the higher this ratio is, the greater the aerodynamic efficiency of the motor-vehicle.

The wheels and with these the respective wheel rims have a significant impact on the aerodynamic resistance and thus the need is felt in the sector to adopt suitable measures to minimise the effects of such resistance.

Another problematic aspect, which must be considered in relation to the wheel rims of the known type for high-performance motor-vehicles, is the expulsion of air from the wheel compartments. For example, the radiators and the diffusers present in the front part of the motor-vehicle create airflows in the area of the respective wheels. Such flows generate an aerodynamic load on the front part of the motor-vehicle and ventilate the area of the wheels. However, the presence of the brake discs of the wheel rims and tires tends to close the wheel compartments, in use, with consequent difficulties in expelling the air entering such spaces; the result is a sort of “inflation” of the wheel compartments, with an increase in local pressure due to the fact that the speed of the air entering the wheel compartments is greater than that being expelled from the same.

Thus, the need is felt in the sector to improve the expulsion of air by the wheel rims during the travel of the vehicle in the forward direction.

DESCRIPTION OF THE INVENTION

It is an object of the present invention to produce a wheel rim for a vehicle, in particular for a motor-vehicle, which allows at least one of the aforesaid needs to be met in a simple and inexpensive manner.

According to the present invention, a wheel rim is made for a vehicle, in particular for a motor-vehicle, as claimed in claim1and in the claims dependent thereon.

The present invention also relates to a vehicle as claimed in claim7.

PREFERRED EMBODIMENT OF THE INVENTION

A front portion of a vehicle is partially shown inFIG. 1, in this case a motor-vehicle1, preferably of the high-performance type. The motor-vehicle1has four wheels3, two front (only one is shown, in particular, the one relating to the left-side drive) and two rear (not shown), and it comprises an outer body4, defining four side wheel compartments5(only one of which is shown, in particular relating to the left-side drive), designed to house the respective wheels3.

Each wheel compartment5is delimited at the side by an arch-shaped bodywork element known as a wheel arch6.

The outer body4comprises, amongst other things, a front bonnet7, a front bumper8, two sides9(only one of which is partially visible) and including respective doors10, and a windscreen11. Furthermore, in the front area between the bonnet7and the bumper8, one or more air intakes12can be present, which, together with respective openings13obtained in the wheel arch6adjacent thereto, allow, during the forward travel of the motor-vehicle1, the generation of airflows, which cross the relative wheel compartment5.

Further airflows towards the wheel compartments5are generated by the radiator (known in itself and not shown), which is usually placed at the front inside the engine compartment of the motor-vehicle1, and/or by the diffuser (also known per se and not shown), positioned on the bottom of the motor-vehicle1.

Some of the aforesaid air flows, which cross, for example, the front wheel compartment5, placed on the left-side drive, and the respective wheel3are indicated by the arrows F inFIG. 1.

With reference to the appended figures, each wheel3essentially comprises a wheel rim15, made according to the teachings of the present invention and fixed, in use, in a known manner, to a relative suspension (also known and not shown) of the motor-vehicle1, and a tire16mounted peripherally onto the wheel rim15.

In particular, the wheel rim15has an axis A, coinciding, in use, with the axis of the wheel3, and comprises:a central hub17configured to be fixed to the respective suspension;a peripheral ring18, which is arranged around the hub17with a predetermined radial distance from the latter and configured to receive the tire16on a radially outermost surface19thereof; anda plurality of spokes20equally spaced angularly from one another around the axis A and connecting the peripheral ring18to the hub17.

As can be seen, in particular, inFIGS. 2 and 4, the peripheral ring18delimits a rear opening21on opposite sides, configured to be arranged, in use, inside the respective wheel compartment5, and a front opening22facing the rear opening21and turned, in use, towards the outside of the motor-vehicle1.

Advantageously, the wheel rim15further comprises one or more projections23, in this case shown in an equal number to the number of the spokes20protruding in a cantilever fashion towards the hub17, starting from a radially innermost surface24of the peripheral ring18, opposite to the radially outermost surface19, and defining an airfoil25(see, in particular,FIG. 3a) configured to generate, in use, during the forward travel of the motor-vehicle1, a channelling of the air entering from the rear opening21towards the front opening and from here, towards the outside of the wheel rim15itself.

In particular, the flow of air across the wheel rim15as diverted by the projections23is shown by way of example, by the arrows F, inFIG. 1.

As can be seen in the attached figures, each projection23is arranged in a position circumferentially interposed between two spokes20adjacent thereto.

Each projection23further has a configuration tapered towards the free end thereof, facing the hub17.

With particular reference toFIG. 3a, the airfoil25defined by each projection23has an attack edge26and an output edge27; the attack edge26is arranged at a distance from the rear opening21, measured parallel to the axis A, which is smaller than that of the output edge27.

In greater detail, with reference to the rotation direction, in use, of the wheel rim15during the forward travel of the motor-vehicle1(anti-clockwise inFIG. 1considering the left-side drive of the motor-vehicle1, clockwise in the case of the right passenger side), the output edge27of the airfoil25of each projection23is arranged circumferentially closer to the spoke20, which follows it, than the attack edge26.

Each wheel rim23is delimited by a first curvilinear surface28facing the front opening22and by a second curvilinear surface29facing the rear opening21; the airfoil25associated with each projection23has (FIG.3a) a back30defined by the curvilinear surface28and a belly31defined by the curvilinear surface29; the back30and the belly31mutually connecting the attack edge26to the output edge27.

As can be seen in detail inFIGS. 2, 3 and 3a, the extension of the back30of the airfoil25defined by each projection23converges towards a front surface of the spoke20, which precedes it with reference to the rotation direction, in use, of the wheel rim15during the forward travel of the motor-vehicle1; differently, the extension of the back30of the airfoil25defined by each projection23is directed towards the rear opening21and extends substantially parallel to the axis A.

With reference toFIGS. 2 and 4, the radially innermost surface24of the peripheral ring18comprises a first circumferential band32adjacent to the front opening22and a second circumferential band33adjacent to the rear opening21; the circumferential bands32and33are adjacent to each other.

As can be noted fromFIGS. 2 and 4, the spokes20and the projections23rest on the circumferential band32of the radially innermost surface24of the peripheral ring18. Furthermore, each projection23extends obliquely along the relative circumferential band32, with the attack26and output edges27of the airfoil25associated with the projection23itself adjacent to the spoke20, which precedes it and to the spoke20, which follows it respectively, with reference to the rotation direction, in use, of the wheel rim15during the forward travel of the motor-vehicle1. In use, during the forward travel of the motor-vehicle1, the projections23of the wheel rim15have the effect of increasing the extractions of air from the respective wheel compartment5, with a consequent reduction in pressure in the respective wheel arch6. In detail, during the forward travel of the motor-vehicle1, the airfoils25generate local accelerations of air especially in the peripheral area of the wheel rim15, i.e. the one which is normally placed in a radially outermost position with respect to the space occupied by the respective brake disc (known in itself and not shown).

More specifically, as can be seen inFIG. 1, the particular geometry of the projections23shaped as airfoils25, as well as the particular arrangement thereof on the peripheral ring18allows the wheel rim15to function like the propeller of an impeller during the forward travel of the motor-vehicle1; this allows air to be expelled from the respective wheel compartment5with considerable efficiency, guaranteeing two main effects (detected in the wind tunnel by means of special models on a scale to 50%):increasing the removal of hot air from the wheel compartment5with consequent benefits on the cooling of the actuator devices mounted on the wheel3, for example callipers and brake disc; andcreating, by vorticity, an air cushion in front of the wheel rim15, which is such that the longitudinal aerodynamic flow on the motor-vehicle1is not affected by the presence of the wheel rim15and remains constant on the respective side9, reducing the Cx of the motor-vehicle.

In this way, it is also possible to obtain the following further effects:reduce the pressure on the wheel arches6;increase the aerodynamic load; andincrease the air flows, crossing the radiators of the motor-vehicle1and then escaping into the wheel arches6.

Finally, it is clear that modifications and variations can be made to the wheel rim15and to the motor-vehicle1described and illustrated here, without thereby departing from the scope of protection defined by the claims.