GB2247867A

GB2247867A - Aerodynamic device for vehicle bonnet

Info

Publication number: GB2247867A
Application number: GB9020229A
Authority: GB
Inventors: Charles Leicester Whitaker
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-09-17
Filing date: 1990-09-17
Publication date: 1992-03-18
Also published as: GB9020229D0

Abstract

The device comprises a substantially laminar element 9 which has its leading edge at/or closely adjacent to the leading edge of the bonnet 2 and which extends rearwardly and spaced apart from the bonnet to form a passage 10 through which the normal air flow over the bonnet passes, when the vehicle is in forward motion, and to provide a negative lift aerodynamic surface spaced from the bonnet surface. Two such devices may be used. A vent may be provided in the vehicle bonnet to provide communication between the interior of the engine compartment and the passage 10 to provide cooling. <IMAGE>

Description

MOTOR VEHICLE BODIES The present invention relates to motor vehicle bodies and more particularly to the bodies of passenger cars or automobiles.

As a result of the high speeds attainable by many present day automobiles, automobile bodies are provided with a variety of appendages the purpose of which is to improve the aerodynamic performance of the vehicle body and, in particular, to increase the aerodynamic downforce on the body in order to improve traction, steering and road-holding generally.

It is known in this context to provide so-called "wings" and "spoilers" at the rear of the vehicle body, such appendages typically being in the form of elongate member extending substantially across the whole width of the rear of the vehicle body.

It is also known to provide an automobile body with a so-called "air-dam" or "spoiler" located at its front end below the bumper. Again the purpose is to reduce the lift at high speed and thus, in this case, increase the steering grip and road-holding between the front tyres and the road.

As indicated earlier, the general purpose of these aerodynamic appendages is to counter the tendency of the automobile body to be lifted off the road surface by the air passing around, over and under it when the vehicle is travelling at high speed.

The present invention is concerned with this general problem of lift at high speed and with providing an improved aerodynamic arrangement for countering this problem.

According to the present invention, an automobile vehicle body of the kind having a bonnet extending forwardly from a passenger compartment is characterised in that it is provided with at least one aerodynamic device at or near the front top surface of the bonnet, the said aerodynamic device comprising a substantially lamina element which has its leading edge at/or closely adjacent to the leading edge of the bonnet and which extends rearwardly and spaced apart from the bonnet to form firstly a passage through which the normal air flow over the bonnet passes, when the vehicle is in forward motion, and secondly to provide a negative lift aerodynamic surface spaced from the bonnet surface.

According to one aspect of the present invention, the bonnet is provided with two said aerodynamic devices located substantially one each side of the said bonnet and being spaced apart from one another with respect to the transverse dimension of the bonnet.

According to another aspect of the present invention, each said aerodynamic device extends in a longitudinal direction with respect to the bonnet a greater distance than it extends in a transverse direction with respect to the bonnet.

According to the further aspect of the present invention, each said aerodynamic device is provided at its trailing end with an aperture so shaped that air impinging on the top of the lamina element will subsequently pass through that aperture to be entrained with air passing through the passage formed between the said element and the bonnet surface.

According to yet another aspect of the present invention, a vent is provided in the bonnet's surface within the passage formed by the bonnet surface and the said element so that air passing over the bonnet surface and below the said element will pass through the vent and into the engine or other compartment defined by the bonnet How the invention may be carried out will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a perspective view of the front of a car embodying the present invention; Figure 2 is an enlarged perspective view of the aerodynamic device showed in Figure 1; Figure 3 is a side elevational view of the device shown in Figures 1 and 2; and Figure 4 illustrates the so-called "NASA" vent which can be incorporated in the present invention.

In Figure 1, a car 1 has a bonnet 2 extending forwardly of a passenger compartment 3, the bonnet 2 in this case containing the engine (not shown) of the vehicle.

The bonnet 2 is of pressed steel construction and slopes downwardly towards a radiator grille 4 which is flanked by an offside pair of headlamps 5 and a nearside pair of headlamps 6. A bumper 7 extends across the front of the car below the grille 4 and headlamps 5 and 6.

The bonnet 2 carries two aerodynamic devices 8A and 8B constructed according to the present invention.

Each aerodynamic device comprises a lamina element 9 which is spaced from and above the surface of the bonnet 2, the spacing being typically about one inch.

The lamina member 9 is connected to the bonnet 2 at its sides 9A and 9B so that together with the bonnet 2 it forms a passage 10 which extends from the leading edge of the bonnet 2 rearwardly of the vehicle. The lamina element 9 is in this example about nine inches wide and twelve inches long.

As the vehicle is driven in a forward direction air can enter the passage 10 at 11 and exit from it at 12.

Because the lamina member 9 is positioned at a negative angle of attack in relation to the forward motion of the car, air flow impinging on the top surface of the lamina member 9 will provide a downward force tending to hold the car on the road and improving the adhesion between the tyres 13 and the road surface.

If because of the styling of the bonnet of the particular car involved it is preferred to have the cross-section of the passage 10 narrower at its rear end than at its front leading end, then there may be some advantage in providing the aerodynamic device with an aperture 14 at or near its rear end top surface. The effect of this is neutralise any build up of pressure within the passage 10 at or towards the rear end thereof. This is achieved because air which passes over the top of the device and then passes through the aperture 14 into the passage 10 accelerates the air in the passage 10. Thus any back pressure which might be created by the relative narrowing of the passage 10 towards its rear end is reduced.

At the same time the lamina member 9 can be utilised to improve the air flow over the front of the car.

In a further modification, the well known so-called NASA vent 15, (see Figure 4) can be provided in the bonnet 2 to provide communication between the interior of the engine compartment of the car and the passage 10. By this means air from the passage 10 can be directed into the engine compartment.

Although the invention has been described and shown in relation to a particular style of car, it can be applied generally to any style. Furthermore, although the car has been shown with two aerodynamic devices, constructed according to the present invention, the car could instead be provided with only one such device or more than two such devices.

To summarise, the device according to the present invention acts as a kind of "bi plane" on the top of the car's bonnet and, due to its negative angle of attack, creates an additional downforce which improves the traction and road-holding. Furthermore, air passing through the passage 10 tends to accelerate and this effect can be combined with a vent in the bonnet 10, (preferrably of the NASA kind) to provide additional cooling air flow into the engine compartment.

Claims

1. An automobile vehicle body of the kind having a bonnet extending forwardly from a passenger compartment is characterised in that it is provided with at least one aerodynamic device at or near the front top surface of the bonnet, the said aerodynamic device comprising a substantially lamina element which has its leading edge at/or closely adjacent to the leading edge of the bonnet and which extends rearwardly and spaced apart from the bonnet to form firstly a passage through which the normal air flow over the bonnet passes, when the vehicle is in forward motion, and secondly to provide a negative lift aerodynamic surface spaced from the bonnet surface.

2. An automobile vehicle body as claimed in claim 1 the in which the bonnet is provided with two said aerodynamic devices located substantially one each side of the said bonnet and being spaced apart from one another with respect to the transverse dimension of the bonnet.

3. An automobile vehicle body as claimed in claim 1 or 2 in which each said aerodynamic device extends in a longitudinal direction with respect to the bonnet a greater distance than it extends in a transverse direction with respect to the bonnet.

4. An automobile vehicle body as claimed in any previous claim in which each said aerodynamic device is provided at its trailing end with an aperture so shaped that air impinging on the top of the lamina element will subsequently pass through that aperture to be entrained with air passing through the passage formed between the said element and the bonnet surface.

5. An automobile vehicle body as claimed in any previous claim in which a vent is provided in the bonnet's surface within the passage formed by the bonnet surface and the said element so that air passing over the bonnet surface and below the said element will pass through the vent and into the engine or other compartment defined by the bonnet.

6. An automobile vehicle body having the arrangements substantially as hereinbefore described with reference to and as shown in the accompanying drawings.