BACKGROUND In wet weather, water spray or splash occurs behind a moving vehicle. It comes mainly from the vehicle's wheels, and that from heavy vehicles can be very troublesome to drivers of following vehicles.

DE 41 18 385 A1 describes an arrangement for limiting splash from wheels of a utility vehicle which includes channels arranged on the outer edges of a mudguard to lead air from outside the vehicle into the space between the wheel and the mudguard, thereby causing the air to accelerate between an outer channel wall and the tyre. The resulting transverse flow counteracts the ejection from the side of the vehicle of water spray between the wheel and the mudguard.

OBJECTS OF THE INVENTION One object of the present invention is to provide an improved arrangement for limiting splash from a wheel on a vehicle.

BRIEF DESCRIPTION OF THE INVENTION The aforesaid object is achieved with a splash prevention arrangement which exhibits the characterising features in patent claim 1.

The invention provides an effective means of drawing air in at the tyre and mudguard of a wheel. This air flow forms in the outer region of the wheel housing an air wall which prevents water splash in the wheel housing from being ejected outside the vehicle.

Movement of water spray towards the outside of the wheel is further prevented by transverse movement in the opposite direction of the air which is pushed into the wheel housing by the splash prevention arrangement.

DESCIPTION OF DRAWINGS The invention is described in more detail below with reference to the accompanying drawings, in which: Fig. 1 depicts a perspective view of a vehicle wheel with a splash prevention arrangement according to a preferred embodiment of the invention, and Fig. 2 depicts a sectional view along the line n-n in Fig. 1.

DETAILED DESCRIPTION Fig. 1 depicts a wheel 1, a mudguard 2 and a splash prevention arrangement 3 which is mounted on the wheel 1. The splash prevention arrangement 3 comprises a basic element 4, preferably substantially planar and substantially circular in shape, and an outer annular flow guide element 5. A multiplicity of flow driving devices 6 arranged at equal mutual spacing in the radial direction extend between the basic element and the flow guide element 5. They have an aerodynamic function described in more detail below.

Preferably, each of the flow driving devices 6 constitutes a structural connection between the flow guide element 5 and the basic element 4. Alternatively, this structural function may be performed by only some of the flow driving devices 6. According to a further alternative, the structural function may be performed by special connecting devices which do not have the aerodynamic function described below.

In Fig. 2, the vehicle's direction of movement is indicated by the arrow P1. The splash prevention arrangement 3 is mounted firmly on the rim 7 of the wheel 1 by means of fastening devices 8 which are commonly used for hubcaps and have a snap-in action which causes them to grip the rim edge when they are fitted. Alternative fastenings for the splash prevention arrangement 3 are of course conceivable, e. g. the splash prevention arrangement 3 may be fastened to the rim 7 by a clamping threaded connection in a manner similar to the way a wheel side on a heavy vehicle is commonly fitted to the wheel.

Fitting the splash prevention arrangement 3 results in the flow guide element 5 being arranged concentrically with a wheel 1 and outside a tyre 9 which is itself fitted to the wheel. At the same time, the flow guide element 5 is situated at such a distance from the outer side of the tyre 9 that a gap 10 is formed between it and the tyre.

As may be seen in Fig. 2, the flow driving devices 6 extend in a radial direction, but as the basic element 4 and the flow guide element 5 are somewhat mutually displaced in the axial direction, the flow driving devices 6 also have a certain extent in the axial direction.

Each flow driving device 6 is similar in shape to a turbine blade and its cross-section exhibits an elongate shape, i. e. a shape similar to a wing profile. Alternatively its cross- section may be planar or take the form of an arcuate plane. The flow driving devices 6 may either be straight or swept so that they partly extend in the wheel rotation direction.

Each flow driving device 6 is designed so that the front edge of the wing profile in the wheel rotation direction is ahead of its rear edge and the slope of the wing profile is adapted in such a way that the radial position of the flow driving device 6 and the rotation speed of the wheel at a certain vehicle speed result in a suitable aerodynamic angle of incidence. This entails the splash prevention arrangement 3 being in the form of two mutually mirror-image versions intended for fitting to wheels on respective sides of the vehicle.

Part of the air flow is represented in Fig. 2 by the arrow P2. When the vehicle is in motion and the wheel 1 (and hence also the splash prevention arrangement 3) rotates, the flow driving devices 6 drive air from the outside of the wheel into the gap 10. The wing profile of each flow driving device 6 is preferably sloped so that maximum air force occurs when the vehicle is travelling at a speed which is usual on a main road.

The air passing through the gap 10 is accelerated by a venturi effect which is encouraged by the tyre's side curvature in the radial direction. As may be seen in Fig. 2, the air flow (indicated by the arrow P2) moves on into the space between the tyre 9 and the mudguard 2. The air flow P2 thus forms a wall between the gap 10 and the outer edge of the mudguard 2. This wall is oriented substantially perpendicular to the axial direction of the wheel 1. The wall is situated at an outer end of the space between the tyre 9 and the mudguard 2 and obstructs transverse movement of air from said space towards the outside of the vehicle. The splash prevention arrangement thus obstructs the escape of water spray and splash from the space between the tyre and the mudguard.