GB2481434A

GB2481434A - Reduced drag cargo carrying vehicle

Info

Publication number: GB2481434A
Application number: GB201010630A
Authority: GB
Inventors: David Joseph Nuttall; Denis Joseph Culloty; Paul D Hancock
Original assignee: Leyland Trucks Ltd
Current assignee: Leyland Trucks Ltd
Priority date: 2010-06-24
Filing date: 2010-06-24
Publication date: 2011-12-28
Anticipated expiration: 2030-06-24
Also published as: GB2481434B; GB201010630D0

Abstract

A cargo carrying vehicle (1 see fig 1) with improved aerodynamic characteristics has a load carrying enclosure (3 see fig 1) located rearwardly of a driver's cab 2 of the vehicle. The enclosure (3) has at least a front wall (4 see fig 1), a roof 5, a base and sides (6 see fig 1). Going in a direction rearwardly of the vehicle (1), the exterior surfaces of the sides (6) have a leading portion 6l extending outwardly over part of the length of the enclosure (3) and a trailing portion 6t extending inwardly towards the rear end of the enclosure. The leading portions 6l of the sides may for example extend over 30 to 40%, preferably 32 to 36% of the length of the enclosure. At the junctions of the leading 6l and trailing 6t portions, the enclosure (3) may be 3 to 12% wider than at the front end of the enclosure (3) with the front and rear ends of the enclosure being of the same width. The leading 6l and trailing 6t portions may be smoothly curved as seen in plan view and may be of aerofoil section. The vehicle (1) may be a "rigid vehicle". Trailers for articulated vehicles are also disclosed.

Description

VEHICLES

The present invention relates to vehicles which are intended to carry cargo.

The invention has particular application to road going, cargo carrying vehicles (e.g. commercial vehicles, trucks and the like) which have a load carrying enclosure located rearwardly of a driver's cab of the vehicle. The invention relates more particularly to reduction of drag resistance for such vehicles.

A load carrying enclosure for a cargo carrying vehicle will comprise a box-like structure with, at least, a front wall, a roof, a base and rigid or flexible sides (e.g. as in a curtain-sided vehicle). Generally the enclosure will be completely closed (at least when the vehicle is travelling along the road), although there will of course be provision to gain access to the enclosure (e.g. a door or the like at the rear of the vehicle).

Examples of such vehicles include so-called "rigid vehicles" in which the load carrying enclosure is rigidly mounted relative to the driver's cab. Further examples include articulated vehicles which comprise a "tractor" incorporating the driver's cab and an articulating trailer connected thereto.

All such vehicles experience drag due to air resistance when travelling along a road. This drag contributes to the fuel (or other energy) consumption required for vehicle travel. Clearly by reducing drag it is possible to reduce the energy costs associated with operation of the vehicle. Furthermore, in the case of vehicles with an internal combustion engine, there is an attendant reduction in the emission of carbon dioxide, carbon monoxide, particulate matter and NOx.

Generally steps taken to reduce drag for the vehicle include provision of a roof spoiler on the top of the driver's cab for deflecting air over the top of the enclosure so that the front wall thereof (which projects above the driver's cab) is not directly impinged upon by the air moving relatively past the vehicle. Other options include the provision of elongate, vertically extending side collars mounted at each side of the driver's cab (towards the rear thereof) and configured to deflect air down the side of the body rather than hitting the front face of the body. Such roof spoilers and side collars do provide a contribution to drag resistance but further improvements are desired.

One proposal for improving drag resistance is disclosed in GB-A-2 443 035 (Don-Bur) which discloses a vehicle with a load carrying enclosure having a roof including a front portion which is inclined upwardly in a rearward direction from the front of the load carrying enclosure and a rear portion which is inclined downwardly to the rear end of the enclosure. Examples of such roofs are described as being of "tear drop" configuration. The vehicle specifically disclosed in the drawings of GB-A-2 443 is an articulated lorry with a relatively long trailer. We have however found that, in the case of a rigid vehicle with a load carrying enclosure of somewhat shorter length than the articulated trailer illustrated in GB-A-2 443 035 such a configuration of roof does not contribute significantly to drag reduction.

It is therefore an object of the present invention to obviate or mitigate the above mentioned disadvantages.

According to a first aspect of the present invention there is provided a cargo carrying vehicle having a load carrying enclosure located rearwardly of a driver's cab of the vehicle, said enclosure having at least a front wall, a roof, a base and sides wherein going in a direction rearwardly of the vehicle the exterior surfaces of said sides have a leading portion which extends outwardly over part of the length of the enclosure and a trailing portion which extends inwardly towards the rear end of the enclosure.

We have found, in accordance with the invention, that configuring the sides of the load carrying enclosure such that the exterior surfaces of the sides have a leading portion which extends outwardly over part of the length of the enclosure and a trailing portion which extends inwardly towards (and preferably to) the rear end of the enclosure provides a significant reduction in drag resistance. Thus, for example, as demonstrated by Case Studies 1 and 2 below, configuring the sides of the enclosure in the manner described provided a drag reduction of about 5% as compared to a similar vehicle in which the sides were wholly planar.

Preferably the leading portions of the sides extend over 30 to 40% of the length of the enclosure. It is particularly preferred that the leading portions of the sides extend over about 32 to 36%, and ideally about 34%, of the length of the enclosure. In preferred constructions of vehicle in accordance with the invention external width of the enclosure as measured where the leading and trailing portions of the sides meet is 3 to 12%, more preferably 7 to 12% (e.g. 8 to 10%) wider than at the front end of the enclosure, the latter preferably (but not necessarily) being the same width as the rear end.

As seen in plan view, the leading portions of the sides are preferably smoothly curved. It is also particularly preferred that the trailing portions are smoothly curved, again as seen in plan view. Preferably the configuration of the leading and trailing portions at each side of the vehicle define aerofoil sections. It is also preferred that the sides of the enclosure are symmetrical with each other. Put another way, the external surfaces of the sides are preferably mirror images of each relative to a central vertical plane of the enclosure extending parallel to the sides.

Although significant improvements in drag reduction may be obtained by configuring the sides of the load carrying enclosure in accordance with the first aspect of the invention further improvements may be obtained using additional measures.

One such measure is to configure the roof of the enclosure such that it has a leading portion rises upwardly from an upper front edge of the enclosure and a trailing portion that extends rearwardly to an upper rear edge of the enclosure. Preferably this leading portion of the roof is smoothly curved. The trailing portion of the roof may be planar or may be inclined downwardly (e.g. in the form of a smooth curve) to the upper rear edge of the enclosure. In preferred embodiments of the invention, the depth of the enclosure (measured externally) at the upstream end of the leading portion of the roof is 3-14%, more preferably 7-14% (e.g. 8-9%) less than where the roof leading portion meets the roof trailing portion. In alternative embodiment, the roof may extend in a planar manner rearwardly from an upper front edge of the body to a point from which the roof inclines downwardly (e.g. in the form of a smooth curve) to the upper rear edge of the body.

In the case where the roof of the enclosure has a leading portion that rises upwardly from an upper front edge of the enclosure, a further improvement in drag reduction may be achieved by providing the roof of the driver's cab with a formation having a forwardly facing surface which is substantially a continuation of the leading portion of the roof. Such a formation may be provided, for example, by a "roof spoiler" provided on the driver's cab.

A further way to reduce drag is to provide the sides of the driver's cab with vertically extending, elongate formations having a forwardly facing surface which is substantially a continuation of the leading portions of the sides of the enclosure. Such formations may, for example, be so-called "cab side collars". A still further way in which drag may be reduced is to provide the vehicle with skirts which are located below the level of the enclosure and extend longitudinally along entire length of the body) having laterally outer surfaces matched to the configuration of the sides.

The invention may be applied to a rigid vehicle, in which case the load carrying enclosure may have external dimensions of, a length of 5-8 metres, a height of 2.5 metres to 2.9 metres and a width of about 2.4 to 2.6 metres. Thus by way of example the enclosure may have the following dimensions * Width, 2480-2540mm * Height, 2594-2876mm * Length, 5100-8410mm However we do not preclude dimensions outside the ranges given in the case of a rigid body vehicle. Moreover, the invention is also applicable to articulated vehicles for which the load carrying enclosure is provided by the trailer of the vehicle and may have a length considerably longer than that given above.

Such a trailer provides an important (second) aspect of the invention in its own right, according to which there is provided a trailer for an articulated vehicle, said trailer comprising a load carrying enclosure having at least a front wall, a roof, a base and sides wherein going in a direction rearwardly of the trailer the exterior surfaces of the sides have a leading portion which extends outwardly over part of the length of the enclosure and a trailing portion which extends inwardly towards the rear end of the enclosure The trailer may be configured in any way as described above for a load enclosure more generally and thus, for example, may have a roof with a leading portion which inclines upwardly from an upper front edge of the load enclosure and then downwardly to the rear edge, in accordance with the teachings of GB-A-2 443 035.

For all embodiments of the invention, the sides of the load carrying enclosure may be made of a rigid material. It is however also envisaged that the invention may be applied to a curtain-sided vehicle with the curtains being configured in accordance

with the foregoing disclosure of the invention.

The invention will be further described by way of example only with reference to the accompanying drawings, in which: Fig 1 is a schematic perspective view of one embodiment of rigid vehicle in accordance with the invention showing particularly the driver's cab and load carrying enclosure thereof (details of the wheels having being omitted for the sake of clarity); Fig 2 is a plan view of the vehicle shown in Fig 1; Fig 3 is a side view of the vehicle shown in Fig 1; Fig 4 is a plan view of a load carrying enclosure of the type for use in the vehicles of Figs 1 and 3 and provides detailed dimensions for its construction; Fig 5 is a side view of the enclosure shown in Fig 4, again with dimensions; Figs 6 and 7 are respectively side and plan views of the results of Case Study 1; Figs 8 and 9 are respectively side and plan views of the results of Case Study 2; Figs 10 and 11 are respectively side and plan views of the results of Case Study 3; and Figs 12 and 13 are respectively side and plan views of the results of Case Study 4.

Illustrated in Figs 1-3 (in perspective, plan and side views respectively) is one embodiment of cargo carrying vehicle 1 in accordance with the invention (but omitting wheels for the sake of clarity) which comprises a driver's cab 2 and a generally box-like load carrying enclosure 3. In conventional manner, enclosure 3 comprises a front wall 4, a roof 5 and side walls 6 together also with a base (not shown). Although not illustrated in the drawings, enclosure 3 has a rear access door through which access to the interior of enclosure 3 may be gained. As viewed from a position in front of the driver's cab (and looking rearwardly) the front wall 4 of enclosure 1 projects laterally outwardly of the cab and also upwardly thereof.

As best seen in the plan view of Fig 2, side walls 6 of enclosure 3 are formed to have a leading portion 61 which (going in a direction rearwardly of the enclosure 3) diverges outwardly from the enclosure front wall 4 to a position (referenced as 7) from which the side walls converge as trailing portions 6t to the rear end of the enclosure 3.

As discussed in more detail below, the length of leading portion 61 is preferably about 34% of the overall length of enclosure 3 (so that the length of trailing portions 6t are correspondingly about 66%). Additionally the width of the enclosure as measured across its widest point (i.e. across the junctions 7) is preferably about 8% greater than the (identical) widths of enclosure 3 at its front and rear ends.

An additional feature of the enclosure 3 as shown in Fig 3 is that the roof 5 has a leading portion SI that rises in the form of a shallow curve from the upper front edge of load carrying enclosure 3 and extends by a distance corresponding to the length of the leading portion 61 of the enclosure sides 6, whereby the leading portion of the roof extends from upper front edge of enclosure 3 to a point corresponding with junction 7.

From this point, the roof 5 has a trailing portion St that extends in a planar manner to the rear end of enclosure 3. In preferred embodiments of the invention, the rise in height of the roof 5 from the upper leading edge of the enclosure to region 7 is about 00/ 0/0.

Although Fig 3 shows the leading portion of the roof rising to a point corresponding with junction 7 it is possible in alternative embodiments of the invention for the roof to rise to a different point, either forwardly or rearwardly of junction 7.

Additional features of the illustrated vehicle include a spoiler 8 mounted on the roof of the driver's cab 2 and being configured such that (when seen in side view -Fig 3) has a front surface substantially following the curvature of leading portion SI of the roof. Furthermore, vertically extending cab side collars 9 are provided at the rear of each side of the cab 2.

All of the features shown in Figs 1 to 3 contribute to drag reduction as compared to a similar vehicle in which the enclosure 3 is cuboid (i.e. the roof 5 and side 6 are wholly planar, and the roof and side spoilers 8 and 9 respectively are omitted.

Additional advantages for the vehicle can be obtained by making it of relatively lightweight construction. Thus, for example, the enclosure 6 may be mounted on an aluminium (rather than steel) subframe. Alternatively or additionally, enclosure 3 may be formed from lightweight panels, e.g. of a sandwich structure which may for example comprise a honeycomb core sandwiched between skins of (for example) glass reinforced plastics.

Reference is now made to Figs 4 and 5 which provide detailed dimensions for a load carrying enclosure 3 incorporated in the vehicles shown in Figs 1-3.

The enclosure shown in Figs 4 and 5 will be seen to have the following dimensions: Dimension Overall Length 6098.13mm Width of Front Wall 2340 mm Height of Front Wall (not including subframe) 2296.50 mm Width of Rear Wall 2340 mm Height of Rear Wall (not including subframe) 2515.00 mm Width Across Junctions 7 2540 mm With particular reference to Fig 4, the leading portions 61 of the sides of the enclosure have a length of 2070.4 mm, corresponding to about 34% of the overall length of the enclosure.

Again with reference to Fig 4, leading portions 61 have a constant radius of curvature along their lengths of 21,483.61 mm whereby they diverge outwardly from the front end of enclosure 3 to the junction 7 from which the trailing portion Gt converge towards each other with a constant radius of curvature along their lengths of 81,161.43 mm to the rear end of the container 6 which is of the same width as the front end. At the junction region 7, the width across the external surfaces of the container 7 is about 2540 mm, as compared to the identical widths at the front and rear ends which are 2340 mm, a difference of about 8.7% (taking 2540 mm as 100%). Put alternatively, the each point 7 lies 100 mm outwardly of the front and rear corners of the enclosure 3 at the same side of the vehicle.

Fig 5 shows dimensional details for the leading portion 51 of the roof. As shown, this portion SI rises from the front of the enclosure 3 to a position corresponding with junction 7 and does so with a constant radius of curvature along its length of 9932.95 mm. From the region of junction 7, roof 5 extends in a planar manner to the rear of enclosure 3. From the front of enclosure 3 to junction 7, the leading portion SI of the roof rises by 218.50 mm to the maximum height of the enclosure which, as shown in the drawing, is 2515.00 mm (excluding sub frame). Thus the leading edge of roof portion rises by about 8.7% in going from the front of enclosure 5 to the maximum height (at junction 7).

The following Case Studies were carried out to establish the benefits of the invention.

Case Study 1 (Invention) Computational Fluid Dynamics (CFD) Simulations were carried out to evaluate the drag reduction achieved by a vehicle construction of the type schematically shown in Figs 1-3. The vehicle had a DAF LF45 Series Cab and the load carrying enclosure was dimensioned as detailed above with reference to Figs 4 and 5. The results are shown in Figs 6 and 7 which are respectively side and plan views of the air flow characteristics produced by the vehicle and clearly show smooth airflow along the roof and sides of the vehicle. More particularly the vehicle of Fig 7 has better matching between cab and body as compared to Fig 11 (see comparative Case Study 3 below) and also a reduced wake at the rear of the vehicle when compared with Fig 11.

Calculations showed that an overall drag reduction of 21.9 % was achieved as compared to a "control" vehicle of the same overall dimensions but having a cuboid enclosure and not being fitted either with the cab roof spoiler 8 or cab side collars 9.

Case Study 2 (Comparative) To evaluate the contribution provided by the sides 6 of the vehicle (and more particularly the effect achieved by the sub-division of the side 6 into leading portions 61 and trailing portions 6t) a further simulation was carried out on a construction of vehicle which was as described above with reference to Figs 1-5 save that the sides were wholly planar (i.e. no leading portion 61 extending outwardly from the front of the load enclosure 3). The results are shown in Figs 8 and 9 (the planar sides being clearly seen in the plan view of Fig 9). Fig 8 shows a very similar result to Fig 6 but the overall drag in this simulation is higher because the wake at the rear of the vehicle is larger in Fig 9 than Fig 7 since the sides are planar (the sides of the vehicle in Case Study 1 allow the air to flow better over the body, causing less air disturbance and thus drag).

Calculations showed that the drag reduction achieved in this instance was 16.6% (as compared to the "control vehicle" detailed above). Thus from a comparison with the results obtained in Case Study 1 above, it can be seen that the sides configured into leading portions 61 and trailing portions 6t provided a contribution of about 5.3% to drag reduction (i.e. 21.9% minus 16.6%).

Case Study 3 (Comparative) For the sake of completeness, a further Case Study was carried out to demonstrate the contribution to drag resistance provided by the roof spoiler and the cab side collars.

For the purposes of this study, the vehicle was configured as in Case Study 3 save that the roof was wholly planar.

The results of the study are shown in Figs 10 and 11 and established that the roof spoiler and side collars together provided a 4.7% reduction in vehicle drag.

Case Study 4 (Comparative) This case study was carried out on a modification of the vehicle which was the subject of Case Study 2 (i.e. one with planar sides), the difference being that (as seen in side view) the trailing portion of the roof was angled downwardly towards the rear end of the load enclosure (as opposed to being planar) in accordance with the teachings of GB-A-2 443 035.

The results are shown in Figs 12 and 13.

It was calculated that this configuration gave a 6.9% reduction in vehicle drag as compared to the control vehicle.

Claims

CLAIMS: 1. A cargo carrying vehicle having a load carrying enclosure located rearwardly of a driver's cab of the vehicle, said enclosure having at least a front wall, a roof, a base and sides wherein going in a direction rearwardly of the vehicle the exterior surfaces of said sides have a leading portion which extends outwardly over part of the length of the enclosure and a trailing portion which extends inwardly towards the rear end of the enclosure.
2. A vehicle as claimed in claim 1 wherein the leading portions of the sides extend over 30 to 40% of the length of the enclosure.
3. A vehicle as claimed in claim 2 wherein the leading portions of the sides extend over 32 to 36% of the length of the enclosure.
4. A vehicle as claimed in claim 3 wherein the leading portion of the sides extend over about 34% of the length of the enclosure.
5. A vehicle as claimed in any one of claims 1 to 4 wherein at the junctions of the leading and trailing portions the enclosure is 3 to 12% wider than at the front end of the enclosure.
6. A vehicle as claimed in claim 5 wherein the front and rear ends of the enclosure are of the same width.
7. A vehicle as claimed in any one of claims 1 to 5 wherein the leading portions are smoothly curved as seen in plan view.
8. A vehicle as claimed in any one of claims 1 to 7 wherein the trailing portions are smoothly curved as seen in plan view.
9. A vehicle as claimed in claim 1 when dependent on claim 7 wherein as seen in plan view the leading and trailing portions at each side of the unit define an aerof oil section.
10. A vehicle as claimed in any one of claims 1 to 9 wherein the trailing portions extend inwardly to the rear end of the enclosure.
11. A vehicle as claimed in any one of claims 1 to 10 wherein the roof of the enclosure has a leading portion that rises upwardly from an upper edge of the enclosure and a trailing portion that extends rearwardly to an upper edge of the enclosure
12. A vehicle as claimed in claim 11 wherein the leading portions of the sides and the leading portion of the roof extend over the same distance along the enclosure
13. A vehicle as claimed in claim 11 or 12 wherein the upstream end of the leading portion of the roof is 3 to 14% lower than the junction at which the roof leading 1 5 portion meets the roof trailing portion.
14. A vehicle as claimed in any one of claims 11 to 13 wherein the trailing portion of the roof is planar.
15. A vehicle as claimed in any one of claims 11 to 13 wherein the trailing portion of the roof extends downwardly towards the rear end of the enclosure.
16. A vehicle as claimed in any one of claims 11 to 15 wherein the roof of the driver's cab has a formation which is substantially a continuation of the leading portion of the roof.
17. A vehicle as claimed in any one of claims 1 to 16 wherein the sides of the driver's cab has formations which are substantially a continuation of the leading portions of the sides of the enclosure.
18. A vehicle as claimed in any one of claims 1 to 17 wherein at each side of the vehicle skirts are provided below the level of the load carrying enclosure, said skirts having a laterally external surface having a configuration corresponding to that of the associated side of the load carrying enclosure.
19. A vehicle as claimed in any one of claims 1 to 18 wherein the sides of the enclosure are symmetrical with each other.
20. A vehicle as claimed in any one of claims 1 to 19 wherein the load carrying enclosure is mounted on an aluminium fame.
21. A vehicle as claimed in any one of claims 1 to 20 wherein the load carrying enclosure is constructed with panels having a honeycomb structure with plastics skins.
22. A vehicle as claimed in any one of claims 1 to 21 which is a rigid vehicle.
23. A vehicle as claimed in claim 21 wherein the load carrying enclosure has, as measured externally thereof, a length of 5-8 metres, a height of 2.5 metres to 2.9 metres and a width of about 2.4 to 2.6 metres.
24. A vehicle as claimed in any one of claims 1 to 21 which is an articulated vehicle.
25. A trailer for an articulated vehicle, said trailer comprising a load carrying enclosure having at least a front wall, a roof, a base and sides wherein going in a direction rearwardly of the trailer the exterior surfaces of the sides have a leading portion which extends outwardly over part of the length of the enclosure and a trailing portion which extends inwardly towards the rear end of the enclosure.
26. A trailer as claimed in claim 25 wherein the load carrying enclosure is as defined in any one of claims 2 to 21.
27. A trailer as claimed in claim 26 wherein the load carrying enclosure is as defined in claim 15.
28. A cargo carrying vehicle substantially as herein for described with reference to Figs 1-3 or Figs 4 and 5 of the accompanying drawings.*.:r: INTELLECTUAL . ... PROPERTY OFFICE 14 Application No: GB 1010630.0 Examiner: Mark Thwaites Claims searched: 1-27 Date of search: 15 October 2010 Patents Act 1977: Search Report under Section 17 Documents considered to be relevant: Category Relevant Identity of document and passage or figure of particular relevance to claims X,Y X 1-5, 7-DE1882859 U 11, 13, (GRASSMANN) esp figures 1 & 2 15, 18, 19, 21-27; Y 6, 16 X,Y X 1-5, 7-US3425740 A 13, 15, (DE VAUGHN) esp figures 1-3 18, 19, 21-27; Y 6, 16 X,Y X1-5.7-CN201165404Y 11, 13, (LUOYANG) esp figures 1-3 & WPI abstract 2009-B01317 [06] 15, 18, 19, 21-27; Y 6, 16 X,Y X 1-5, 7-FR2834496 Al 13, 15, (QUEGUINER) esp figures 1-8 & WPI abstract 2003-69 1611 [66] 18, 19, 21-27; Y 6, 16 X,Y X 1-5, 7-US6595578 Bi 10, 18, (CALSOYAS) esp figures 1 & 2 19, 21-27; Y 6, 16 X,Y X1-5,7-FR2263142A1 11, 13-15, (SCHMITZ)esp figures 1 &2 18, 19, 21-27; Y 6, 16 X,Y Xl-5,7-GB2460126A 13, 15, (HAWORTH) esp figures 1 & 2 18, 19, 21-27; Y 6, 16 Intellectual Property Office is an operating name of the Patent Office www.ipo.gov.uk *.:r: INTELLECTUAL 15 . ... PROPERTY OFFICE X,Y Xl-5,7-US6631941B1 11, 13, (VOTRUBA) esp figure 1 15, 18-27; Y 6, 16 X,Y X25;Y6 US4566717A (ARTHUR) esp figure 1 Y 6, 16 GB2443035 A (BON BUR) whole document relevant Categories: X Document indicating lack of novelty or inventive A Document indicating technological background and/or state step of the art.Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of before the filing date of this invention.same category.& Member of the same patent family E Patent document published on or after. hut with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP, WO & US patent documents classified in the following areas of the UKCX: Worldwide search of patent documents classified in the following areas of the IPC B6OP; B62D; B62K The following online and other databases have been used in the preparation of this search report Online: EPODOC, WPI, TXTE, Internet International Classification: Subclass Subgroup Valid From B62D 0035/00 01/01/2006 B62D 0025/02 01/01/2006 B62D 0063/06 01/01/2006 Intellectual Property Office is an operating name of the Patent Office www.ipo.gov.uk