GB2029342A - Aerodynamic Deflecting Devices for Vehicles - Google Patents

Abstract

A deflector (35) is attached to the roof of a car and is shaped to direct air upwardly and outwardly over and round a caravan being towed by the car to reduce the air resistance and drag created by the caravan when being towed. Preferably a roof rack has a front deflector (25) mounted at its front and a main deflector (35) mounted at its roar. The front deflector is arranged to deflect air on to the main deflector and the main deflector is arranged to direct air upwardly and sidewardly over and round the caravan. Both deflectors are adjustable. <IMAGE>

Description

SPECIFICATION Aerodynamic Devices for Vehicles This invention relates to an aerodynamic device and more particularly to a device for fitting to a car which is to tow a caravan.

A caravan by its functional shape is an aerodynamic monstrosity and incurs high air resistance and high drag forces. Most owners estimate that fuel consumption of a car rises by thirty per cent when towing a caravan and this is due to extra weight plus aerodynamic forces.

Aerodynamic design of caravans to minimise air resistance and drag forces is impractical because of cost/size complications. As cars become more aerodynamically streamlined, the volume of backwash air hitting the forward face of the caravan increases dramatically.

An object of the present invention is to provide a device which will reduce the air resistance and drag forces created by a caravan when being towed.

A further object is to reduce the fuel consumption of a car towing a caravan.

The present invention provides an aerodynamic deflector and mounting means for fixing the deflector to the roof of a car the deflector being shaped to direct air upwardly and outwardly over and round a caravan being towed by a car to which the deflector is fixed. The deflector normally has a width of at least 80 per cent that of the car, the width preferably corresponding to the width of the car but not being greater than the car's width.

In a preferred form the deflector has a central longitudinal ridge and curves downwardly and outwardly from the ridge to form a wing on each side. The ridge itself is sloped upwardly towards the rear and the wings each have a side edge and a trailing edge which curves rearwardly and outwardly from the apex of the ridge. The curve of the wings is such that for a four feet wide deflector the rearmost tips of the wings are from four to eight inches below, and preferably six inches below, the apex of the ridge.

The mounting means preferably allows rotational adjustment of the deflector about a horizontal axis so as to vary the angle to 200 on either side of an optimum angle of about 450 to the horizontal.

The deflector may be attached direct to the roof of the car but is preferably attached to the car roof gutter by a roof rack or a clamp and crossbar.

In a preferred form the invention provides a combined roof rack and deflector means, comprising a roof rack having means for fixing to the roof of a car, a first deflector mounted on the front of the roof rack, a second deflector mounted on the rear of the roof rack, the first deflector being arranged to deflect air onto the second deflector and the second deflector being arranged to direct air upwardly and sidewardly over and round a caravan being trailed by a car to which the combination is fixed. The second deflector will normally be shaped as described above.

Embodiments of aerodynamic devices will now be described by way of example only with reference to the accompanying drawings of which: Figure 1 is a longitudinal section through a roof rack and deflector means showing the car roof line and the outline of part of a caravan, Figure 2 is a plan view of the device of Figure 1, Figure 3 is a front elevation of the device of Figure 1, and Figure 4 is a side view of a car fitted with an alternative form of deflector means.

The roof line of a car is indicated at 12 (Figure 1) with the car having a towing hitch 13 (Figure 2) to which a caravan indicated at 14 is attached.

The roof has a gutter indicated at 1 5 to which a roof rack 1 6 is clamped in conventional manner. It will be appreciated that any suitable form of roof rack may be used but the one shown is particularly suitable. The roof rack has a front cross bar 17, a rear cross bar 18 and sides each of which consist of upper and lower longitudinal bars 1 9 and 20 respectively connected to the crossbars 1 7 and 1 8. The lower bars 20 are connected by further crossbars 21 and the upper and lower bars 19 and 20 are connected by upright struts 22 the frame comprised by the bars 1 7, 18, 19, 20, 21 and 22 is supported from the gutter by bars 23.

A first deflector 24 comprises a rectangular panel 25 having strengthening ribs 26 on its rear face each of which is slidably located in a slotted end of a tube 27 and secured therein by a clamp bolt at 28 so that the deflector can be adjustable relative to tubes 27 in the direction of arrow 30 parallel to its surface and can undergo limited pivotal movement about the horizontal axis 31.

Each of the tubes 27 is slidably located in a tubular clamp 32 which is attached to the front crossbar 1 7. This allows the tubes to be moved parallel to their axes in the direction of arrow 33 so that the deflector is adjustable for height in a direction parallel to its plane and in a direction normal to its plane and can be rotated about axis 31.

A second deflector 35 is attached at the rear of the roof rack and the first deflector is adjusted so as to deflect air onto the second deflector. This reduces the air resistance of the roof rack and any luggage on the roof rack. The deflector 35 is aerodynamically shaped so as to direct air over the roof and round the sides of the caravan and thereby reduce the air resistance caused by the caravan. The deflector 35 has a central ridge 36 from which extend symmetrically on either side a pair of curved wings 37.The leading edge 38 of the deflector 35 is pivotally attached to a crossbar 39 which extends across the roof rack and is attached by clamps 40 to the upper longitudinal bars 1 9. The underside of the ridge 36 is formed centrally with a rib 41 to which is pivotally attached a stay 42 which is adjustably clamped in a tubular clamp 43 attached to the centre of the crossbar 18. Movement up or down of the stay 42 causes pivotal movement of the deflector about the axis of crossbar 39 and allows adjustment of the angle which the deflector makes with the horizontal through 200 on either side of an optimum of about 450. The wings 37 curve outwardly and downwardly away from the ridge with their side edges curving upwardly and outwardly and the trailing edges curving rearwardly and outwardly. The wing tips are preferably about six inches below the apex of the ridge for a five foot span of deflector.

Figure 4 shows diagrammatically an alternative simpler deflector 45 attached directly to the roof of a car 46. This deflector is preferably of the same shape as deflector 35 of Figures 1 to 3. The deflector may be attached by a crossbar and clamps to the gutter of a car roof or may be attached to some other form of roof rack.

It will be appreciated that the angles of the deflectors can be adjusted for different caravans and cars to obtain optimum reduction of air resistance. When the car is not towing a caravan the whole combination may be removed or only the deflector 35 removed when the roof rack is required. Equally the deflector 24 could be removed leaving the roof rack and deflector 35 or simply leaving the roof rack.

Claims (10)

Claims

1. An aerodynamic deflector and mounting means for fixing the deflector to the roof of a car, the deflector being shaped to direct air upwardly and outwardly over and round a caravan being towed by a car to which the deflector is fixed.

2. A combined roof rack and deflector means, comprising a roof rack having fixing means for fixing to the roof of a car, a front deflector mounted on the front of the roof rack, a main deflector mounted on the rear of the roof rack, the front deflector being arranged to deflect air on to the main deflector and the main deflector being arranged to direct air upwardly and sidewardly over and round a caravan being trailed by a car to which the combination is fixed.

3. A deflector or combination according to Claim 1 or Claim 2 in which the deflector or the main deflector has a width of at least 4 feet.

4. A deflector or combination according to any of Claims 1 to 3 in which the deflector or the main deflector has a central longitudinal ridge and curves downwardly and outwardly from the ridge to form a wing on each side.

5. A deflector or combination according to Claim 4 in which the ridge is sloped upwardly towards the rear and the wings each have a side edge and a trailing edge which curves rearwardly and outwardly from the apex of the ridge.

6. A deflector or combination according to Claim 5 in which the curve of the wings is such that the rearmost tips of the wings are from 4" to 8" below and preferably 6" below the apex of the ridge.

7. A deflector or combination according to any of Claims 1 to 6 in which the deflector or the main deflector is rotatable about a horizontal axis.

8. A deflector or combination according to Claim 7 in which the deflector is rotatable so as to vary the angle by 200 on either side of an optimum angle of 450 to the horizontal.

9. A combination according to Claim 2 or any claim dependent thereon in which the front deflector is adjustable in height and in a horizontal direction relative to the roof rack.

10. A combination of roof rack and deflector substantially as described herein with reference to Figures 1 to 3 of the accompanying drawings.