GB2519518A - An air deflector - Google Patents

Abstract

A tail light assembly air deflector 134 for a commercial vehicle (e.g. trailers, trucks, lorries) where the tail light assembly (see figure 11), during forward motion of the vehicle, is at least partly disposed in the path of air passing over or beneath the main body of the vehicle. The deflector has a first 136 and second 137 airflow surfaces which extend forwardly of the assembly to a leading edge 135, so that air is caused to flow around the assembly, reducing the aerodynamic drag which the assembly exerts on the vehicle. The deflector may be formed of an outer skin with indentations/recesses 200. The invention also details an air deflector for a rear bumper of underrun bar. Preferably the drag reduction apparatus also comprises a guard scoop for directing airflow and a second deflector 210.

Description

Title: An Air Deflector

Technical Field of the Invention

This invention relates, in broad terms, to the field of aerodynamic drag reduction in the realm of commercial vehicles. More particularly, but not exclusively, the invention relates to the reduction of drag and turbulent airflow which exists immediately and closely behind commercial vehicles such as HGVs, articulated container vehicles and the like.

Background to the Invention

Ever since commercial vehicles have become a feature on today's roads, widespread and concerted efforts have been made to improve such vehicles' efficiency, so as to reduce fuel costs, engine wear and (more recently) the emission (from the engines) of various noxious and otherwise undesirable gases such as unburned hydrocarbons and carbon dioxide.

Improvements in engine and fuel technology have gone some way towards addressing these issues but the simple physics of a body (i.e. the vehicle) being caused to move through a fluid (atmospheric air) means that aerodynamic drag remains, and will always be, a significant problem which vehicle designers and commercial haulage operators need to address.

As a consequence, much work in recent years has been done in the area of automotive aerodynamics, with a view to reducing drag (a physical force which acts parallel to and in the same direction as the airflow -and hence in the opposite direction to the vehicle's motion), wind noise and vehicle/road noise emission (for human environmental reasons), and in relation to the prevention of various causes of aerodynamic instability at relatively high speeds. Whilst rolling resistance (the inherent resistance to movement of a vehicle, caused by the vehicle's mass, engine components, frictional forces and the like), is an important factor in fuel consumption! aerodynamic drag is widely considered to be responsible for about 50% of a commercial vehicle's fuel usage. As aerodynamic drag increases significantly in line with (specifically, with the square of) a vehicle's speed, it is evidently a significant problem with commercial vehicles which operate both at relatively high speeds (on motorways/highways) and over long distances -and hence extended periods of time. This problem is exacerbated by motorways and highways often being in "windy" environments, where the effects of drag are increased.

In consequence, much work has been done in relation to the reduction of vehicles' drag co-efficients, by altering the shape and materials of vehicles' external surfaces, both in relation to commercial vehicle tractor units (i.e. the front/cab component, which powers the container or pulls the trailer, as appropriate) and the trailer/container unit itself. In the case of container/trailer units, to which the present invention particularly relates, such efforts have concentrated around upper and side aspects of the container or trailer unit.

For example, it is now common to see teardrop or sloping roofs as part of articulated container units, as well as aerodynamic rear mud flaps, boat tail / Kammback configurations towards the rear, and aerodynamic side panels/side wings which extend beneath (and which run parallel to) the main container sides, at least partially covering the rear wheel and axle assemblies.

By way of commercial example, the "Cheetah" ® range of aerodynamic trailers, available from The Cartwright Group (see wwwcartwripht features a variety of innovative elements which, in combination, enable fuel savings of up to 12% over a standard "box" trailer, and carbon emissions savings of up to around 18 metric tonnes, per year.

Given that the annual fuel spend of major UK logistics / haulage operators can amount to almost £200 million per year, it will be understood that even relatively modest fuel savings, in percentage terms, can amount to a very significant actual financial benefit.

In addition to this financial advantage, however, the reduction of drag also has important benefits in terms of engine wear, noise emissions and vehicle reliability.

There are also important safety aspects which come into play. Chiefly, these relate to the reduction of turbulent airflow immediately and closely behind the moving container (or trailer), as turbulent air in this region (caused in part by the road wheels and movement of the transverse axle) is effective to "gather up" water, snow, dirt and other particulate matter from the road surface and to "kick up" that matter into the space just behind the moving container, causing significant visibility problems for a vehicle which may be following closely behind. This is especially important when a following vehicle is considering (or making) an overtaking manoeuvre, where an increased speed will be required, into a highway lane of which the visibility is already obstructed by a part of the container body itself.

Overall, despite progress in many areas, there remain a number of parts of commercial vehicles which continue to impart significant amounts of aerodynamic drag to the vehicle, and where problems thus continue to exist.

Overview of the Prior Art

Aerodynamic improvements in the area of commercial vehicle trailers and containers have tended to focus on devices which, in use, are disposed forwardly (i.e. in front of) the rear wheels or set of wheels. Canadian patent no. 1156293 (Martin, Aubrey M), published in 1983, discloses an aerodynamic fairing for placement under the undercarriage of a tractor (or trailer) and which is placed in front of the transverse axle carrying the road-running wheels, with the fairing apparently being effective to reduce drag on the vehicle and to reduce the air turbulence which exists in the vehicle's wake. The fairing is attached directly to the vehicle's undercarriage / underbelly, and has the effect of diverting air away from the underbelly, and under the transverse axles of the rear wheel set.

US patent no. 4262953 (Premix, Inc., published in 1981) also discloses an undermounted air deflector for trucks and trailers, in the form of an air foil / deflector panel which is angled / positioned to deflect air downwardly and rearwardly so that most of the air which is incident on the deflector is deflected between the rear wheels, to alleviate the vacuum which would otherwise exist at the rear of the vehicle body. The leading edge of the deflector is preferably made straight "to enable positioning [of] the deflector so the smallest gap will exist between the underside of the vehicle floor to minimise the amount of horizontally travelling air which might leak past the deflector when the vehicle is in motion. The object is to direct as much air as possible downwardly and rearwardly for the airstream to pass between the innermost vehicle wheels to the region behind the rear of the vehicle".

Summary of the Invention

In accordance with a first aspect of the present invention, there is provided a tail light assembly air deflector for a commercial vehicle, where the tail light assembly, during forward motion of the vehicle, is at least partly disposed in the path of air passing over or beneath the main body of the vehicle, the deflector having first and second airflow surfaces which extend forwardly of the assembly to a leading edge, so that air is caused to flow around the assembly, reducing the aerodynamic drag which the assembly exerts on the vehicle.

The first and second airflow surfaces may converge towards the leading edge of the deflector.

The forward extension of the leading edge preferably reduces towards at least one end of the deflector. Conveniently, the forward extension of the leading edge reduces towards both ends of the deflector.

The first and second airflow surfaces may provide a generally convex forward surface of the deflector.

The tail light assembly, in use, may be disposed generally horizontally such that the first and second airflow surfaces are upper and lower airflow surfaces, and cause said air to flow over and beneath the assembly.

The upper and / or lower airflow surfaces may comprise at least one indentation or recess.

The or each indentation or recess may have a concave inner surface. The / each indentation may extend generally perpendicular to a principal axis of the deflector.

The / each indentation may be disposed between, but spaced from, the leading and trailing edges of the deflector.

The reducing depth of the deflector, towards said end or ends, may provide a flow path for air which is laterally incident upon the deflector, reducing the lateral aerodynamic drag which the deflector would otherwise exert on the vehicle.

The or each end may have a side airflow surface which is joined to or is integral with the leading edge of the deflector.

The side airflow surface may be joined to or integral with the first and second airflow surfaces of the deflector.

The side airflow surface may be generally convex.

The deflector may have two end portions and an intermediate portion, the end and intermediate portions being moveable relative to each other such that the overall length of the deflector may be adjusted, prior to installation or use.

Preferably, the end and intermediate portions are slideable relative to each other.

The first and second airflow surfaces may terminate at trailing edges which are disposed rearwardly of an assembly support surface, on which the tail light casings are mounted.

The deflector may comprise releasable attachment means such that the deflector may be removed from or adjusted in relation to the assembly.

The first and second airflow surfaces may be generally symmetrical about the principal axis of the assembly.

In accordance with a second aspect of the present invention, there is provided a tail light assembly for a commercial vehicle comprising an air deflector substantially in accordance with the first aspect of the invention.

In accordance with a third aspect of the present invention, there is provided a rear bumper or underrun bar assembly air deflector for a commercial vehicle where the assembly, during forward motion of the vehicle, is at least partly disposed in the path of air passing beneath the main body of the vehicle, the deflector having first and second airflow surfaces which extend forwardly of the assembly to a leading edge so that air is caused to flow around the assembly, reducing the aerodynamic drag which the assembly exerts on the vehicle, the first and second airflow surfaces converging towards the leading edge and the forward extension of the leading edge reducing towards at least one end of the deflector.

The air deflector, in accordance with the third aspect of the present invention, may comprise one or more of the features of the first or second aspect.

In accordance with a fourth aspect of the present invention, there is provided drag reduction apparatus for use towards the rear of a commercial vehicle comprising: i) a guard scoop for directing airflow inwardly of and under a side wall of the vehicle and which is disposed rearwardly of the vehicle's rear wheels; and ii) an air deflector in accordance with any of the preceding paragraphs; a trailing surface of the guard scoop and a leading surface of the air deflector being spaced so as to provide an air passage between them, the passage allowing laterally-incident air to flow between the scoop and air deflector, thus reducing the drag co-efficient of the rear of the vehicle.

In accordance with a fifth aspect of the present invention, there is provided a commercial vehicle having an air deflector or drag reduction apparatus, in accordance with any of the preceding paragraphs.

Each aspect of the present invention may incorporate one or more features of the other aspects, as described above.

Detailed Description of the Invention and Preferred Embodiments Preferred and non-limiting embodiments of the various aspects of the present invention will now be described in greater detail, but strictly by way of example only, by reference to the accompanying drawings, of which: Figure 1 is a schematic illustration of a known type of aerodynamic commercial vehicle trailer, to which the invention particularly relates; Figure 2 is a close-up view, in perspective, of the rear of a prior art aerodynamic container, similar to that of Figure 1; Figure 3 is a perspective view, from one side and from below, of an air deflector of the type to which the present invention relates, mounted on a light bar assembly support of the type shown in Figure 2; Figure 4 is a perspective view, from above and one side, of the tail light assembly and air deflector of Figure 3; Figure 5 shows (at A, B and C) schematic airflow diagrams, showing the beneficial effect/turbulence reduction of the air deflector of the present invention; Figure 6 illustrates, in graphical form, the drag reduction effects of various configurations of air deflector; Figure 7 shows an alternative embodiment of air deflector, from above and one side; Figure 8 is a view, from above, of the deflector of Figure 7; Figure 9 is a side end-on view of the deflector of Figure 7; Figure 10 shows (from above and one side) the deflector of Figure 7, with an end portion removed; Figure 11 shows the deflector of Figure 7, from a rearward position; and Figure 12 shows the deflector of Figure 7, in isolation.

Referring first to Figure 1, this shows, in schematic form, an aerodynamic trailer 10 of the type which, in use, is attached to and pulled by a tractor / motor unit, by way of a "fifth wheel" coupler, which engages with the underside of the trailer, towards the right of the image shown. The trailer 10 is generally conventional, save that it features a number of aerodynamic components designed to improve aerodynamic efficiency and to reduce drag / turbulence, for the reasons described above. The trailer thus comprises a curved rear roof 11, a rounded front spoiler 12, an aerofoil 13 (not shown in detail), aerodynamic side guards 14, rear wheel covers 15, an open rear chassis 16 and enlarged rear guard scoops 17 which are integral with a curved rear underrun bar 18 which lies generally flush, but spaced below from, the lower edge of the main container body 19. As will be well understood by those skilled in the relevant art, the combined effect of the aerodynamic side guards 14, the rear wheel covers 15 and the rear guard scoops 17 is to direct as much airflow as possible underneath and down the centre of the container body, or closely around the sides of the side guards and wheel covers, with the rear guard scoops 17 channelling the "side" air in a relatively smooth, non-turbulent manner towards the rear of the container.

Although not shown in Figure 1 (for reasons of clarity) the space between the underrun bar 18 and the lower edge of the main container body 19 is conventionally and commonly occupied by the vehicle's tail light assembly.

Shown more clearly in Figure 2, which illustrates a slightly different configuration of aerodynamic trailer, the arrangement includes a tail light bar to which tail light I indicator housings 21 are mounted, in a rearward-facing direction. A number of apertures I mounting points are provided on the tail light bar 20 so that the tail light casings 21 can be attached at a suitable position, taking into account the width of the trailer or the size of the tail light casings themselves. In the arrangement shown in Figure 2, a separate underrun bar 22 is shown, which is spaced from the rear guard scoops 17, with the rear wheel covers 1 5a not covering the wheels to the same degree as the components 15 shown in Figure 1. What will be clear from Figure 2 is that the beneficial effects of the rear guard scoops 17 are significantly compromised / adversely affected by the presence, in the "downstream" position, of the metal plate which forms the bulk of the tail light bar 20. The positioning (i.e. height above the road surface) of the tail light bar is governed by a number of regulations which mean, in practice, that it is often "at odds" with the position and configuration of aerodynamic devices towards the rear of commercial vehicles / trailers, which are designed to reduce drag and the consequential "kick up" of spray and debris, in the vehicle's wake.

Compounding the problem is that, for reasons of economy and ease of manufacture, tail light assemblies of this type are generally produced from flat metal plates, not least to facilitate easy / economical replacement, in the event of damage, which is quite common, given the positioning of this component.

Figure 3 illustrates, in detail, how the present invention provides significant advantages over such prior art tail light assembly constructions.

Figure 3 shows a tail light assembly 30 mounted to a substructure 31 of a commercial vehicle or trailer, with the tail light assembly 30 being mounted to the substructure 30 by way of two downwardly-depending brackets 32, to the ends of which is affixed a box-section underrun bar 33, of generally conventional type. As will be understood, the primary purpose of the underrun bar 33 is to provide a barrier to any other vehicle (or occupant) who may inadvertently come into contact with the lower part of the vehicle or trailer, lessening the risk of serious injury I head trauma, as the following vehicle runs underneath the container or trailer body.

Figure 3 illustrates, in detail, the air deflector 34 of the present invention. The air deflector 34, in this embodiment, is made up of three components 34a, 34b and 34c which are moveable (slideable) relative to one another. To facilitate this, the central / intermediate component 34b is provided with a number of tongues which extend from its ends into correspondingly-configured recesses or slots disposed in the mating ends of the end parts 34a and 34c. This allows adjustment of the deflector to take place, during installation.

The deflector, which in this example is moulded (ideally, vacuum-formed) from a rigid plastics material such as ABS, has a leading edge 35 which, in use, is disposed in the airflow path, which exits from beneath and around the sides of the vehicle 10. The leading edge 35 thus extends forwardly (in the sense of the vehicle's travel) of the tail light assembly, with the degree of that extension reducing towards the ends 34a and 34c of the deflector body. In other words, as can be seen from Figure 3, the deflector tapers gradually towards the end parts 34a and 34c, for the reasons described below. In addition, in this embodiment, the upper airflow surface 36 and lower airflow surface 37 converge towards the leading edge 35, and are generally symmetrical about a horizontal plane which bisects the air deflector along the horizontal axis H-H, shown in the figure. The effect of this is that air which is incident upon the air deflector 34 is split (in terms of flow) substantially evenly, into airflows which run over and beneath the deflector, along the upper and lower airflow surfaces 36 and 37. From an aerodynamic perspective, this provides an optimum result, as no net downforce (or lift) is created. However, for aesthetic reasons and in view of space constraints, the applicants envisage (see Figures 7 to 12) that asymmetrical arrangements may also be employed.

Figure 4 shows the air deflector and tail light assembly from a rearward position, and shows the interaction of the air deflector 34 with the rear guard scoops 17 of the type generally shown in the preceding figures.

As can be seen from Figure 4, the end walls 40 (of which only one is shown, for convenience) have a substantially flat portion 41 and a curved, forwardly extending portion 42 which (in this example) meets and is integral with the upper and lower airflow surfaces 36 and 37, as well as the leading edge 35, in a curved and smooth manner.

The effect of this is that the end walls 40 curve "into" the sides of the container, providing an airflow surface for the passage of air which may be incident laterally on the rear of the trailer.

Research indicates that cross winds (i.e. laterally-directed winds) of up to 5 metres per second are relatively common on British (and other) motorways and these can have a noticeable and sometimes serious effect on both the stability of the rear of the trailer and on the generation of spray / kicked-up debris, in the space immediately behind it. Reducing any sideways movement (known commonly as fishtailing) of the rear of a trailer is important both for safety reasons and to reduce wear on the wheel / axle arrangement, as those skilled in the art will appreciate. This is especially the case with double -articulated trailers, as the effects of fishtailing" can be magnified.

Providing a specifically-configured airflow path to the ends of the air deflector casing allows any air which is laterally incident on the ends of the air deflector to be channelled smoothly around the forward surfaces of the air deflector, thus reducing the effective air resistance of the deflector assembly.

This effect is particularly pronounced where the deflector is placed close to, but slightly spaced from, the trailing surface 43 of the rear guard scoop 17.

The passage between the trailing surface 43 and the leading surface of the deflector allows the laterally-incident air to pass between them (with the benefits described above) but the relative close proximity of the trailing and leading surfaces ensures that any clean (i.e. non-turbulent) air which is conveyed from the scoops will pass to the air deflector relatively uninterrupted.

It will, of course, be appreciated that the presence of any rear guard scoops is not required in order for the benefits of the air deflector to be appreciated.

Whilst Figure 3 and 4 show the air deflector 34 being used in conjunction with the tail light assembly 30, the air deflector 34 can equally find use and applicability in conjunction with the underrun bar 33 or any other similar structure (e.g. a rear bumper) of that general type. In short, the significant aerodynamic benefits of the air deflector (calculated by the applicants as being a 66% drag reduction in comparison to a flat plate, equating to a 1.12% fuel saving estimate) could be realised by the placement of the air deflector in a number of different positions.

In terms of attachment, any suitable form of attachment means may be employed, with the applicants envisaging that a "clip-on" arrangement may be particularly suitable, alternatively / additionally with a number of threaded fasteners, which may be suitably configured to engage with the pre-existing apertures in the tail light assembly bar.

Figure 5 illustrates, in schematic terms, the effect of two different configurations of tail light assembly air deflector, as compared to the use of a

conventional / prior art "flat plate" design.

In more detail, Figures 5A, 5B and 50 are schematic airflow diagrams showing the different types of airflow in the wake of a relatively fast moving commercial trailer. As can be seen from Figure 5A (where the image has been produced with a standard "flat plate" tail light assembly in position), the turbulent airflow behind the trailer continues for a substantial distance in the vehicle's wake. In practice, this means that any "kicked-up" water, spray, debris or oil will persist at a height (above the road) which is dangerous for following vehicles, and for a considerable distance.

Figure 5B illustrates the effect of another embodiment of the air deflector of the present invention, as applied to a tail light assembly of the type described. In the arrangement shown in Figure SB, the air deflector has one principal -concave -airflow surface which directs a proportion of the incident air upwardly and over the tail light assembly, with the base of the deflector being substantially flat. The overall shape of the deflector of Figure 5B can thus be considered something akin to a right angled triangle, where the hypotenuse has a concave configuration.

Figure 50 illustrates the effects and benefits of the air deflector of the embodiment of Figures 3 and 4, having substantially symmetrical upper and lower airflow surfaces, as shown in Figures 3 and 4. As will be appreciated, the flow pattern is markedly different from that of Figures 5A and 5B, in that the upper edge of the turbulent flow decreases in height far more rapidly, meaning that any trailing spray will "drop" to a safe height at a shorter distance behind the trailer than with the other configurations. Whilst not shown in this illustration, the applicants have also found that the amount of turbulent flow in the region immediately / closely following the trailer is significantly reduced, meaning that the amount of spray / debris which is "kicked-up" by the trailer is itself reduced. Equally, and as importantly, however, the aerodynamic drag exerted on the trailer is significantly reduced by use of the present air deflector.

Figure 6 illustrates, using relative data, the extent to which an aerodynamic trailer is "held back" as a result of its overall aerodynamic drag, with different configurations of tail light assembly air deflector. Figure 6 also illustrates the aerodynamic drag effect of a standard "flat plate" tail light assembly, and a configuration in which no tail light assembly at all is present. What can be seen, from Figure 6, is that the "concave triangle" configuration of Figure SB exhibits the greatest reduction in aerodynamic drag, with the dual airflow configuration of Figure 5C being closely comparable. However, experimentation by the applicants has also showed that the configuration of Figure SB resulted in a significant amount of downforce which (for reasons of fuel efficiency, amongst others), is clearly undesirable, in a commercial vehicle context. Overall, the configuration shown in Figure SC exhibited the most advantageous flow characteristics, drag reduction and the greatest reduction of turbulent air, together with the most favourable "shaping" of the rear wake, providing significant safety advantages over the other configurations.

Indeed, the applicants have found that use of the air deflector of the present invention (as shown schematically in Figure 5C) "shapes" the rear wake even better than where no tail light assembly at all is present in the airflow path.

Referring next to Figures 7 to 12, these show an alternative embodiment of air deflector, having a generally asymmetrical configuration, as opposed to the symmetrical configuration of the embodiment referred to in Figures 3 to 6. For the sake of convenience, and as the component parts are substantially in accordance with those of Figures 2 to 6, identical reference numerals have been used, with the addition of 100. In consequence, Figures 7 to 12 show an air deflector generally indicated at 134, having upper and lower airflow surfaces 136 / 137 and end walls 140 (having substantially flat portions 141 and curved, forwardly extending portions 142). The air deflector 134 is mounted to the vehicle structure by way of brackets 132, which also hold an underrun bar 133 which, in this embodiment, is of generally circular cross section, as opposed to the box section of Figures 3 and 4. In the embodiment of Figures 7 to 12, the air deflector 134 is comprised of three sections 134a, 134b and 134c, which again are slideably separable so as to facilitate installation on I around the brackets 132. The tail light assembly 130 and substructure 131 are also shown.

The key difference between the embodiment of Figures 7 to 12 and that of Figures 3 and 4 is the configuration of the air deflector and, more specifically, its generally asymmetrical nature, with respect to the horizontal plane which bisects the air deflector along the horizontal axis H-H, shown in Figure 3.

As is perhaps best shown in Figure 9, the upper airflow surface 136 extends away from the leading edge 135 (and thus from the horizontal plane) at a steeper angle than does the lower airflow surface 137.

In addition to this asymmetric difference, which can result from pure aesthetic considerations, and perhaps space constraints beneath the floor of the vehicle / container, the embodiment of Figures 7 to 12 also differs in the sense that the upper airflow surface 136 is provided with a number of generally longitudinal indentations / recesses, formed into the outer surface (or "skin") of the deflector 134. As mentioned above, the air deflector 134 is moulded / vacuum-formed from a plastics material such as ABS, resulting in a substantially hollow configuration, providing both weight and cost benefits.

The substantially hollow deflector 134 is thus composed of an outer skin and it is within this skin that the indentations / recesses 200 are provided. The recesses do not completely penetrate the skin of the air deflector 134 but instead comprise indentations which provide generally concave inner surfaces 201 having a generally curved recessed inner surface. As can be seen in the figures, this embodiment has three substantially parallel indentations (of differing lengths) within each part 134a, 134b and 134c of the deflector 134 although it will be appreciated that more, or fewer, could of course be provided. The applicants have found that these indentations, which lie generally in the air flow direction (when the vehicle is in motion) provide both extra strength to the deflector 134 (useful in the event that stones / debris are thrown up from the road surface) and also serve a useful aerodynamic purpose.

In more detail, the applicants understand that the indentations serve to energise the boundary layer which exists just above the surface of the deflector 134, which it is thought assists in the prevention of separation of the air flow over and beneath the deflector 134.

In practical terms, this is advantageous because it reduces the formation of turbulent flow immediately behind / closely behind the vehicle, which adds to the safety benefits referred to above.

The embodiment of Figures 7 to 12 also features an additional aerodynamic component in the form of a supplementary air deflector 210.

The supplementary deflector 210 extends downwardly from the lower airflow surface 137 and is intended to deflect air away from a licence plate holder 211 which, in conventional fashion, is mounted on the light bar 120, at a slightly off-centre position. Given the different sizes (i.e. height / width) of international licence plates, it is common that such holders 211 protrude beneath the lower edge of the metal light bar 120 (to which the tail light casings 121 are attached), thus providing yet another obstacle to air flow, exiting from beneath the vehicle body or container. The purpose of the supplementary deflector 210 is to divert air beneath the licence plate holder 211, further assisting in the reduction of drag which the vehicle would otherwise suffer from. It will be appreciated that a variety of sizes and configurations are possible for the supplementary deflector 210 but the applicants envisage that, in a preferred embodiment, the deflector will be formed integrally with the central part 134b of the main deflector 134.

Figure 10, illustrating an incomplete air deflector 134 (in that the end part 1 34c is missing) shows how parts 134a, 134b (and 134c) can slideably be attached together. As shown, the central part 134b has, at its ends, a stepped configuration 230, lying slightly inset from the upper air flow surface 136 by virtue of a step 231, with the slightly reduced size of the end allowing the end part 134c of the deflector (not shown in Figure 10) to be slid over it, and attached in conventional manner.

Figures 9 and 12, in particular, also illustrate a difference in the end walls 140, as compared to the end walls 40 of the first embodiment shown. Specifically, the end walls 140 have a slightly smaller (reduced area) flat portion 141, meaning that the curved, forwardly extending portion 142 is enlarged, as compared with the corresponding portion 42 of the first embodiment. This allows an easier passage of laterally-directed air flow, further reducing the effective (lateral) air resistance of the deflector assembly.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (24)

1. CLAIMS1. A tail light assembly air deflector for a commercial vehicle where the tail light assembly, during forward motion of the vehicle, is at least partly disposed in the path of air passing over or beneath the main body of the vehicle, the deflector having first and second airflow surfaces which extend forwardly of the assembly to a leading edge, so that air is caused to flow around the assembly, reducing the aerodynamic drag which the assembly exerts on the vehicle.
2. 2. An air deflector according to claim 1 wherein the first and second airflow surfaces converge towards the leading edge of the deflector.
3. 3. An air deflector according to claim 1 or claim 2 wherein the forward extension of the leading edge reduces towards at least one end of the deflector.
4. 4. An air deflector according to any one of the preceding claims wherein the forward extension of the leading edge reduces towards both ends of the deflector.
5. 5. An air deflector according to any one of the preceding claims wherein the first and second airflow surfaces provide a generally convex forward surface of the deflector.
6. 6. An air deflector according to any one of the preceding claims wherein the tail light assembly, in use, is disposed generally horizontally, such that the first and second airflow surfaces are upper and lower airflow surfaces and cause said air to flow over and beneath the assembly.
7. 7. An air deflector according to any one of claims 3 to 6 wherein the reducing depth of the deflector, towards said end, provides a flow path for air which is laterally incident upon the deflector, reducing the lateral aerodynamic drag which the deflector would otherwise exert on the vehicle.
8. 8. An air deflector according to any one of claims 3 to 7 wherein the or each end has a side airflow surface which is joined to or is integral with the leading edge of the deflector.
9. 9. An air deflector according to claim 8 wherein the side airflow surface is joined to or is integral with the first and second airflow surfaces of the deflector.
10. 10. An air deflector according to claim 7, claim 8 or claim 9 wherein the side airflow surface is generally convex.
11. 11. An air deflector according to any one of the preceding claims having two end portions and an intermediate portion, the end and intermediate portions being moveable relative to each other such that the overall length of the deflector may be adjusted, prior to installation or use.
12. 12. An air deflector according to claim 11 wherein the end and intermediate portions are slideable relative to each other.
13. 13. An air deflector according to any one of the preceding claims wherein the first and second airflow surfaces terminate at trailing edges which are disposed rearwardly of an assembly support surface, on which the tail light casings are mounted.
14. 14. An air deflector according to any one of the preceding claims comprising releasable attachment means such that the air deflector may be removed from or adjusted in relation to the assembly.
15. 15. A tail light assembly for a commercial vehicle comprising an air deflector in accordance with any one of the preceding claims.
16. 16. An air deflector according to any one of the preceding claims wherein the first and second airflow surfaces are generally symmetrical about the principal axis of the assembly.
17. 17. A rear bumper or underrun bar assembly air deflector for a commercial vehicle where the assembly, during forward motion of the vehicle, is at least partly disposed in the path of air passing beneath the main body of the vehicle, the deflector having first and second airflow surfaces which extend forwardly of the assembly to a leading edge so that air is caused to flow around the assembly, reducing the aerodynamic drag which the assembly exerts on the vehicle, the first and second airflow surfaces converging towards the leading edge, and the forward extension of the leading edge reducing towards at least one end of the deflector.
18. 18. An air deflector according to claim 17 further comprising one or more of the features of claims 1 to 16.
19. 19. Drag reduction apparatus for use towards the rear of a commercial vehicle comprising: i) a guard scoop for directing airflow inwardly of and under a side wall of the vehicle and which is disposed rearwardly of the vehicle's rear wheels; and ii) an air deflector in accordance with any of claims 1 to 18; a trailing surface of the guard scoop and a leading surface of the air deflector being spaced so as to provide an air passage between them, the passage allowing laterally-incident air to flow between the scoop and air deflector, thus reducing the drag co-efficient of the rear of the vehicle.
20. 20. An air deflector substantially as hereinbefore described and/or as shown in the accompanying drawings.
21. 21. A tail light assembly substantially as hereinbefore described and/or as shown in the accompany drawings.
22. 22. Drag reduction apparatus substantially as hereinbefore described and/or as shown in the accompany drawings.
23. 23. A commercial vehicle having an air deflector or drag reduction apparatus in accordance with any one of the preceding claims.
24. 24. Any novel feature or novel combination of features described herein and/or as shown in the accompanying drawings.