EP1827953A1

EP1827953A1 - Deflector

Info

Publication number: EP1827953A1
Application number: EP05813437A
Authority: EP
Inventors: Andrew Berenyi
Original assignee: Wake Trimmer Pty Ltd
Current assignee: Wake Trimmer Pty Ltd
Priority date: 2004-12-06
Filing date: 2005-12-05
Publication date: 2007-09-05
Also published as: CA2593529A1; WO2006060852A1; EP1827953A4

Abstract

A deflector (10) for mounting at a rear of a vehicle (12), the deflector (10) being arranged, in operation, to project sidewards of the vehicle (12) as one or more ducts (22, 26, 28) to direct air from along a side (14) of the vehicle (12) through a region (30) behind the vehicle (12) and allow continuous airflow through the region (30) and behind the vehicle (12) to thereby reduce vacuum effect, the deflector (10) being adapted to move to a retracted condition, when not in use, to allow unobstructed opening of a rear door of the vehicle (12). Similarly a method of reducing drag of a moving vehicle by mounting of a deflector to the vehicle is disclosed.

Description

DEFLECTOR

Field of the Invention

This invention relates to a deflector, and more particularly, but not exclusively, to an air deflector for reducing drag behind a vehicle.

Background of the Invention

Motor vehicles are often produced with a box-like shape in order to maximise useable internal space. This is particularly the case with a type of commercial vehicle which comprises a powered cab and a box-shaped trailer towed by the cab. Commercial vehicles of this kind are often used for carrying boxed stock and, while the box-shaping of the trailer is beneficial for fitting a maximum amount of boxed stock, the box-shaping has poor aerodynamic characteristics. These characteristics are accentuated at higher speeds at which vehicles of this type often travel, for example on motorways between a stock pickup location and a stock drop-off location. Accordingly, the poor aerodynamics of these vehicles cause losses in the form of excessive fuel consumption and, as a result, financial loss in fuel costs.

It has been proposed to improve aerodynamics of commercial vehicles by fitting a sloped deflector to a roof of a truck cab to assist the passage of air over the top of the trailer. However, while this has improved aerodynamics at the front of the vehicle, large losses still occur at the rear of the vehicle. More particularly, during forward motion, a substantial low pressure zone exists immediately behind the flat rearward surface of the trailer, and this low pressure zone creates drag, resulting in higher consumption of fuel than if the low pressure zone were removed or reduced in magnitude.

Efforts have been made to reduce or remove the low pressure zone by providing air deflectors to edges of a rearward surface of a vehicle, as shown in United States Patent No. 4,320,920. However these air deflectors have not been adopted widely. Smnmary of the Invention

In accordance with one aspect of the present invention, there is provided a deflector for mounting at a rear of a vehicle, the deflector being arranged, in operation, to project sidewardly of the vehicle as one or more ducts to direct air from along a side of the vehicle through a region behind the vehicle and allow continuous airflow through the region and behind the vehicle to thereby reduce vacuum effect, the deflector being adapted to move to a retracted condition, when not in use, to allow unobstructed opening of a rear door of the vehicle.

Preferably, the deflector is adapted for mounting to the vehicle at or near a transition between a side surface of the vehicle and a rearward surface of the vehicle.

Preferably, the deflector is deformable such that, when a door of the vehicle is opened, the deflector is deformed into the retracted condition so as to be confined between the door and a part of the vehicle. More preferably, the deflector is compressible such that, when the door is opened, the deflector is compressed between the door and a side surface of the vehicle.

Preferably, the deflector is adapted such that, when the door is closed, the confinement of the deflector is removed and the deflector returns to its operating condition. More preferably, the deflector is adapted such that, when the door is closed, the deflector is assisted in returning to its operating condition by the effect of air deflected by the deflector.

Preferably, the deflector is made from collapsible material such as, for example, woven fabric, plastic sheeting, rubber, or rubberised fabric. More preferably, the material is resilient. Preferably, the deflector comprises a series of deflector segments, with pairs of adjacent segments being separated by a membrane coupled to the vehicle. More preferably, the membrane extends in a plane substantially parallel to the direction of movement of the vehicle relative to the air.

Preferably, the deflector is in the form of an airfoil. More preferably, the deflector is in the form of a self-inflating "ram-air" airfoil.

In one form, there is provided a pair of deflectors, each as described above, a first of the deflectors being adapted for mounting on one side of the vehicle, and the other deflector being adapted for mounting on the opposite side of the vehicle.

In accordance with another aspect of the present invention, there is provided a vehicle fitted with a pair of deflectors as described above. Preferably, the vehicle is also fitted with a deflector mounted at or near a top transition between a top surface of the vehicle and the rearward surface of the vehicle to project above said top transition as one or more ducts to direct air from along the top surface of the vehicle through a region behind the vehicle and allow continuous airflow through the region and behind the vehicle to thereby reduce vacuum effect.

In accordance with another aspect of the present invention, there is provided a method of reducing drag of a moving vehicle, including the step of mounting a deflector to the vehicle, the deflector being deformable so as to move between an operating condition for diverting air behind the vehicle, and a retracted condition when not in use to allow unobstructed opening of a rear door of the vehicle, wherein, in the operating condition, the deflector projects sidewardly of the vehicle as one or more ducts to direct air from along a side of the vehicle through a region behind the vehicle and allow continuous airflow through the region and behind the vehicle to thereby reduce vacuum effect.

In accordance with another aspect of the present invention, there is provided a collapsible deflector for mounting at a rear of a vehicle, wherein the deflector is collapsible - A -

so as to be movable between an operating condition in which airflow from along a side of the vehicle is ducted by the deflector through a region behind the vehicle to allow continuous airflow through the region and behind the vehicle to thereby reduce vacuum effect, and a collapsed condition to allow unobstructed opening of a rear door of the vehicle.

Preferably, the collapsible deflector is in the form of an airfoil. More preferably, the deflector is in the form of a self-inflating "ram-air" airfoil.

Brief Description of the Drawings

The invention is described, by way of non-limiting example only, with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic front/side perspective view of a trailer fitted with a deflector in accordance with an example of the present invention;

Figure Ia is a diagrammatic close-up perspective view of an upper portion of the deflector shown in Figure 1 ;

Figure Ib is a diagrammatic close-up perspective view of a segment of a deflector in accordance with an example of the present invention;

Figure 2 is a diagrammatic rear/side perspective view of a trailer fitted with a pair of deflectors in accordance with an example of the present invention;

Figure 3 is a diagrammatic top view of a truck fitted with a pair of deflectors;

Figure 4 is a diagrammatic top view of a rear corner of a vehicle fitted with an existing deflector; Figure 5 is a diagrammatic top view of a rear corner of a vehicle fitted with a deflector in accordance with an example of the present invention;

Figure 6 is a diagrammatic top view of the rear corner of Figure 5, shown with a door of the vehicle in an open configuration;

Figure 7 is a side perspective view of a ram-air parachute;

Figure 8a is a modelled diagram of static pressure about a truck not fitted with deflectors;

Figure 8b is a modelled diagram of static pressure about a truck fitted with deflectors;

Figure 9a is a modelled diagram of velocity magnitude about a truck not fitted with deflectors;

Figure 9b is a modelled diagram of velocity magnitude about a truck fitted with deflectors;

Figure 10a is a modelled diagram of velocity vectors about a truck not fitted with deflectors;

Figure 10b is a modelled diagram of velocity vectors about a truck fitted with deflectors;

Detailed Description

A deflector 10 for diverting air behind a vehicle 12 so as to reduce drag of the vehicle when the vehicle 12 is moving relative to the air is shown in Figure 1. The deflector 10 is pliable such that it is able to be deformed to adapt to a confined space, and is able to return to an operating condition after removal from the confined space.

The deflector 10 is mounted to a trailer 13 of the vehicle 12 at a transition between a side surface 14 and a rearward surface 16 of the trailer 12. As shown in Figure I₅ a rear end 18 of the trailer 13 has a generally box-like shape such that the transition between the side surface 14 and the rearward surface 16 occurs at a generally vertical side rear edge 20 of the trailer 13.

The deflector 10 comprises a series of deflector segments 22, with pairs of adjacent segments 22 being separated by a membrane 24 coupled to the vehicle 12. The segments 22 are arranged in line along the length of the side rear edge 20 of the trailer 13. Each segment 22 has an inlet opening 26 which opens toward a front of the vehicle 12, and an outlet opening 28 which opens toward a region 30 behind a rearward surface 32 of the trailer 13. Each of the segments 22 is curved laterally between the inlet opening 26 and the outlet opening 28 such that it provides a duct through which air fed into the inlet opening 26 is redirected to the region 30 behind the rearward surface 32 of the trailer 13. As the rear end 18 of the trailer 13 has a generally box-like shape, without the use of the deflector 10 the region 30 would normally be a low pressure zone during forward motion of the vehicle 12 (particularly when the vehicle 12 is travelling at speed), which would create drag resulting in increased fuel consumption. However, by redirecting air into this region 30 during forward motion of the vehicle 12 the low pressure zone is prevented or at least reduced such that drag and fuel consumption are reduced.

The membranes 24 separating adjacent pairs of deflector segments 22 are attached to the side of the trailer 13 to strengthen attachment of the deflector 10 to the vehicle 12, and are oriented in generally horizontal planes parallel to the direction of motion of the trailer 13 relative to surrounding air. The direction of forward motion of the trailer 13 relative to the surrounding air is indicated by arrow 34. Figure Ia shows a close-up view of the upper three segments 22 of the rear left- hand deflector 10 shown in Figure 1, and Figure Ib shows a close-up view of a top-most segment 22 of a rear right-hand deflector 10 fitted to a vehicle 12.

As shown clearly in the rear/side perspective view of Figure 2, one deflector 10 is fitted to each side edge of the rear of the trailer 13. Advantageously, this provides similar aerodynamic benefits to each side of the vehicle 12 to optimise savings in fuel consumption and to maintain even handling characteristics. With reference to Figure 2, when the vehicle 12 is moving forward, surrounding air (represented by arrow 36) travelling rearwardly along the side surface 14 of the trailer 13 is fed into the inlet openings 26 of the deflector 10, and is directed by the deflector 10 to the region 30 behind the rearward surface 32 of the trailer along the path represented by arrow 38. This direction of the air by the deflector 10 is also shown in the top views of Figure 3 and Figure 5.

Additional like deflectors may also be provided along an upper rear edge and/or a lower rear edge of the trailer 13 to further reduce drag on the vehicle 12.

In one example, the deflector segments 22 extend approximately 50mm from the side surface 14 of the trailer 13 (see reference numeral 40 in Figure Ib). This enables the inlet openings 26 to be of sufficient size to deflect a useful amount of air for having a significant effect on the aerodynamics and fuel consumption of the vehicle 12. However, this protrusion of the deflectors 10 from the sides 14 of the trailer may pose problems when the space occupied by the deflectors 10 is required for other purposes. For example, where there are outwardly opening rear doors 42 on the trailer 13, the space occupied by the deflectors 10 may be required by the doors 42 in order to reach their fully open configuration. For example, as shown in Figure 4, where a deflector is rigid it may not be possible to open the doors 42 to their fully open configuration unless complicated hinges are used to accommodate the deflector between the door 42 and a side surface 14 of the trailer 13. This inability to fully open the doors 42, or the need to fit laterally-extending hinges to accommodate the deflector, may result in the trailer 13 being unable to fit within certain spaces, such as between walls of a loading bay.

Advantageously, the deflector 10 is made from collapsible material such as, for example woven fabric, plastic sheeting, rubber, or rubberised fabric. Accordingly, as demonstrated in Figures 5 and 6 in which the door 42 is closed and open respectively through an angle of approximately 270 degrees, the deflector 10 is able to be deformed from an operating condition into a retracted condition so as to be confined between the door 42 and the side surface 14 of the trailer 13 to allow the door to be opened to its fully open configuration. When loading or unloading of the vehicle 12 has been completed and the doors 42 of the trailer 13 are closed for driving of the vehicle 12 to its next destination, the deflectors 10 are able to be returned to their operating condition (ie. their deflecting shape as shown in Figures 1 to Ib). This return of the deflectors 10 to their operating condition may be assisted by resilience in the material of the deflectors 10 whereby they automatically return at least partly to their operating condition. The return to the operating condition may also be assisted by the air deflected by the deflectors 10, which air serves to inflate the deflectors 10 in a manner similar to that for a ram air parachute as shown in Figure 7.

Deflectors 10 in accordance with examples of the present invention may employ principles similar to modern parachutes which are self-inflating "ram-air" airfoils that provide control of speed and direction similar to paragliders. Paragliders have much greater lift and range, but parachutes are designed to handle, spread and mitigate the stresses of deployment at terminal velocity. All ram-air parafoils have two layers of fabric; top and bottom, connected by shaped fabric I-beams and/or gores. The space between the two fabric layers fills with high pressure air from vents that face forward on the leading edge of the airfoil. The fabric is shaped and the parachute lines trimmed under load such that the ballooning fabric inflates into an airfoil shape.

The above deflectors have been described by way of example only and modifications are possible within the scope of the invention. For example, although the deflectors are described as being used for reducing drag on a motor vehicle moving through air, it is to be understood that the deflectors may also be used for reducing drag of other forms of vehicles moving through air or other fluids.

Figures 8a to 1 Ob are diagrams of static pressure, velocity magnitude and velocity vectors for a truck with and without deflectors, as generated by a computer model. Each of these computer-generated diagrams shows a truck 12 moving toward the left-hand side of the page. In Figures 8a, 9a and 10a the truck 12 is modelled without deflectors, in Figures 8b, 9b and 10b the truck 12 is modelled with deflectors 10.

With particular reference to Figures 8a and 8b, as can be seen, the deflectors 10 result in a more even distribution of static pressure behind the truck 12, including a significant reduction in the size and intensity of the low pressure zones 44. The computer- modelled testing also demonstrated that the deflectors resulted in a reduction of drag force from 767N to 670N, a reduction of over 12.6%.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A deflector for mounting at a rear of a vehicle, the deflector being arranged, in operation, to project sidewardly of the vehicle as one or more ducts to direct air from along a side of the vehicle through a region behind the vehicle and allow continuous airflow through the region and behind the vehicle to thereby reduce vacuum effect, the deflector being adapted to move to a retracted condition, when not in use, to allow unobstructed opening of a rear door of the vehicle.

2. A deflector as claimed in claim 1, wherein the deflector is adapted for mounting to the vehicle at or near a transition between a side surface of the vehicle and a rearward surface of the vehicle.

3. A deflector as claimed in claim 1 or claim 2, wherein the deflector is deformable such that, when a door of the vehicle is opened, the deflector is deformed into the retracted condition so as to be confined between the door and a part of the vehicle.

4. A deflector as claimed in claim 3, wherein the deflector is compressible such that, when the door is opened, the deflector is compressed between the door and a side surface of the vehicle.

5. A deflector as claimed in claim 3 or claim 4, wherein the deflector is adapted such that, when the door is closed, the confinement of the deflector is removed and the deflector returns to its operating condition.

6. A deflector as claimed in claim 5, wherein the deflector is adapted such that, when the door is closed, the deflector is assisted in returning to its operating condition by the effect of air deflected by the deflector.

7. A deflector as claimed in any one of the previous claims, wherein the deflector is made from collapsible material such as, for example, woven fabric, plastic sheeting, rubber, or rubberised fabric.

8. A deflector as claimed in claim 7, wherein the material is resilient.

9. A deflector as claimed in any one of the previous claims, wherein the deflector comprises a series of deflector segments, with pairs of adjacent segments being separated by a membrane coupled to the vehicle.

10. A deflector as claimed in claim 9, wherein the membrane extends in a plane substantially parallel to the direction of movement of the vehicle relative to the air.

11. A deflector as claimed in any one of the previous claims wherein the deflector is in the form of an airfoil.

12. A deflector as claimed in claim 11, wherein the deflector is in the form of a self- inflating "ram-air" airfoil.

13. A pair of deflectors, each of the deflectors being a deflector as claimed in any one of claims 1 to 12, wherein a first of the deflectors is adapted for mounting on one side of the vehicle, and the other deflector is adapted for mounting on the opposite side of the vehicle.

14. A vehicle fitted with a pair of deflectors as claimed in claim 13.

15. A vehicle as claimed in claim 14, wherein the vehicle is also fitted with a deflector mounted at or near a top transition between a top surface of the vehicle and the rearward surface of the vehicle to project above said top transition as one or more ducts to direct air from along the top surface of the vehicle through a region behind the vehicle and allow continuous airflow through the region and behind the vehicle to thereby reduce vacuum effect.

16. A method of reducing drag of a moving vehicle, including the step of mounting a deflector to the vehicle, the deflector being deformable so as to move between an operating condition for diverting air behind the vehicle, and a retracted condition when not in use to allow unobstructed opening of a rear door of the vehicle, wherein, in the operating condition, the deflector projects sidewardly of the vehicle as one or more ducts to direct air from along a side of the vehicle through a region behind the vehicle and allow continuous airflow through the region and behind the vehicle to thereby reduce vacuum effect.

17. A collapsible deflector for mounting at a rear of a vehicle, wherein the deflector is collapsible so as to be movable between an operating condition in which airflow from along a side of the vehicle is ducted by the deflector through a region behind the vehicle to allow continuous airflow through the region and behind the vehicle to thereby reduce vacuum effect, and a collapsed condition to allow unobstructed opening of a rear door of the vehicle.

18. A collapsible deflector as claimed in claim 16, wherein the deflector is in the form of an airfoil.

19. A deflector as claimed in claim 18, wherein the deflector is in the form of a self- inflating "ram-air" airfoil.