GB2546894A

GB2546894A - Air guiding device for a cab of a commercial vehicle

Info

Publication number: GB2546894A
Application number: GB1700891.3A
Authority: GB
Inventors: Madugundi Dinesh; Agarwal Ankit; Lucescu Ruben; Hartung Rex; Caccia Paul
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2017-01-19
Filing date: 2017-01-19
Publication date: 2017-08-02
Also published as: GB201700891D0

Abstract

An air guiding device 42 for a cab 16 of a commercial vehicle 10 comprises air guiding element 44 which, in at least one state overlaps at least a portion of an A-pillar 24 of the cab and is arranged at a distance from the portion. A portion of an outer surface (50, figure 3) of the air guiding element is preferably curved and / or may face towards the A pillar or away from the A pillar. The A pillar may have an outer surface (52) with a corresponding shape to the air guiding element outer surface. There may be a second air guiding element 46 overlapping a second A pillar 26 of similar features to that of the first.

Description

Air Guiding Device for a Cab of a Commercial Vehicle

The invention relates to an air guiding device for a cab of a commercial vehicle.

Commercial vehicles such as trucks or tractors are well-known from the general prior art. Such a commercial vehicle is, for example, configured as a motor vehicle and comprises a cab in which the driver of the commercial vehicle can sit and operate the commercial vehicle. Moreover, DE 40 14 577 C1 shows an air guiding device for the front of a cab of a commercial vehicle, the air guiding device comprising at least one air guiding profile arranged in front of a body of the commercial vehicle.

It is an object of the present invention to provide an air guiding device by means of which particularly advantageous aerodynamics of a commercial vehicle can be realized.

This object is solved by an air guiding device having the features of patent claim 1. Advantageous embodiments with expedient developments of the invention are indicated in the other patent claims.

The air guiding device for a cab of a commercial vehicle such as, for example, a truck or a tractor comprises, according to the present invention, at least one air guiding element which, in at least one state of the air guiding element, overlaps at least a portion of an A-pillar of the cab and is arranged at a distance from the portion of the A-pillar. The air guiding element can act as an external aero device which can be attached to the A-pillar to improve aerodynamic performance of the A-pillar, in particular in side wind conditions.

It was found that the effectiveness of the A-pillar to keep airflow attached to the commercial vehicle, in particular the cab, as the airflow passes around a corner from a wind shield to e.g. a vehicle door and/or another adjacent longitudinal surface of the vehicle depends on build-up of adverse pressure gradients to flow acceleration around the A-pillar in the flow direction. Conventionally, the effectiveness of the A-pillar to keep the air flow attached to the cab diminishes in a side wind condition primarily on the leeward side of the vehicle. Thus, conventionally, in particular in a side wind condition, the airflow can separate from the cab, in particular on the leeward side of the vehicle. In order to avoid such an excessive separation of airflow from the cab the air guiding device according to the present invention helps control the airflow around the A-pillar and potentially reduces flow separation so that particularly advantageous aerodynamics of the commercial vehicle can be realized. Hence, the energy consumption, in particular the fuel consumption, of the commercial vehicle can be kept particularly low. In other words, in comparison with conventional commercial vehicles an aerodynamic performance improvement can be realized by means of the air guiding device according to the present invention thereby reducing fuel consumption.

Further advantages, features, and details of the present invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respective indicated combination but also in any other combination or taken alone without leaving the scope of the invention.

The drawings show in:

Fig. 1 a schematic top view of a conventional commercial vehicle according to the prior art;

Fig. 2 part of a schematic front view of a commercial vehicle having an air guiding device according to the present invention;

Fig. 3 part of a schematic and sectional top view of the commercial vehicle according to Fig. 2;

Fig. 4 part of a schematic and perspective side view of a cab of the commercial vehicle according to Fig. 2; and

Fig. 5 part of a schematic front view of a hood of the commercial vehicle according to Fig. 2.

In the figures the same elements or elements having the same functions are indicated by the same reference signs.

Fig. 1 shows in a schematic top view a conventional commercial vehicle 10 according to the prior art. As can be seen from Fig. 1, the commercial vehicle 10 is configured as a tractor being a motor vehicle configured to be pivotably connected to a trailer 12 which can be moved by said tractor. The commercial vehicle 10 has a frame 14 and a cab 16 in which a driver of the commercial vehicle 10 can sit and operate the commercial vehicle 10, the cab 16 being mounted on the frame 14. Moreover, the commercial vehicle 10 comprises a hood 18 which is, at least partially, arranged in front of the cab 16 with respect to the longitudinal direction of the vehicle. In Fig. 1, the longitudinal direction of the vehicle is illustrated by a directional arrow 22.

The cab 16 is a body comprising two A-pillars 24 and 26 which are arranged opposite each other in the transverse direction of the vehicle, the transverse direction being illustrated by directional arrow 28. Said A-pillars 24 and 26 bound a windscreen opening of the cab 16, said windscreen opening being configured as a through opening. Moreover, the cab 16 comprises a windscreen 30 which is also referred to as a windshield and arranged in said windscreen opening and, thus, between the A-pillars 24 and 26 in the transverse direction of the vehicle. In Fig. 1, arrows 32 and 34 illustrate an airflow flowing against and around the hood 18 and the cab 16 when, for example, the commercial vehicle 10 travels forwards. In Fig. 1, a side wind condition is illustrated, wherein in said side wind condition air and, thus, wind flow against the commercial vehicle 10 angularly to the longitudinal direction of the vehicle.

Moreover, the commercial vehicle 10 comprises exterior mirrors 36 which are, for example, arranged adjacent to the A-pillars 24 and 26. For example, the cab 16 bounds lateral door openings which are configured as through openings. As can be seen from Fig. 4, a side door 38 is assigned to the respective door opening, the respective side door 38 being pivotably arranged on the cab 16 so that the respective side door 38 can be pivoted in relation to the respective A-pillar 24 or 26 respectively between a closed position and at least one open position. For example, the respective side door 38 comprises at least one side window 40.

In said side wind condition illustrated in Fig. 1, the A-pillar 24 is arranged on a so-called leeward side of the commercial vehicle 10, in particular the cab 16. It has been found that the effectiveness of the respective A-pillar 24 or 26 to keep airflow attached to the commercial vehicle 10, in particular the cab 16, as it passes around the corner from the windscreen 30 to, for example, the respective side door 38 and/or at least one other adjacent longitudinal surface of the commercial vehicle 10, in particular the cab 16, depends on build-up of adverse pressure gradients due to flow acceleration around the respective A-pillar 24 or 26 in the flow direction. The effectiveness of the respective A-pillar 24 or 26 to keep the airflow attached diminishes in a side wind condition, primarily on said leeward side of the commercial vehicle 10 as illustrated in Fig. 1. As can be seen in Fig. 1, the airflow can separate from the cab 16 on the leeward side, wherein said flow separation is illustrated by said directional arrows 34.

In order to control the airflow around the respective A-pillar 24 or 26 and potentially reduce flow separation so as to realize particularly advantageous aerodynamics of the commercial vehicle 10, the commercial vehicle 10 is equipped with an air guiding device 42 as shown in Figs. 2 to 4. As can be seen from Fig. 2, the air guiding device 42 comprises a first air guiding element 44 which, in at least one state of the air guiding element 44, overlaps at least a portion of the A-pillar 24 and is arranged at distance from the portion of the A-pillar 24. Moreover, the air guiding device 42 comprises a second air guiding element 46 which, in at least one state of the air guiding element 46, overlaps at least a portion of the A-pillar 26 and is arranged at a distance from the portion of the A-pillar 26. As can be seen from Fig. 3, the air guiding element 44 is arranged adjacent to the corresponding A-pillar 24. Previous and following advantages and implementations described with respect to the air guiding element 44 and the corresponding A-pillar 24 can also be adapted to the air guiding element 46 and the corresponding A-pillar 26. Thus, for example, the air guiding element 46 is arranged adjacent to the corresponding A-pillar 26. As can be seen from Fig. 3, the air guiding element 44 and the corresponding A-pillar 24 bound at least one through opening 48 through which air and, thus, said airflow flowing against and around the cab 16 can flow. For example, the through opening 48 acts as a vane, in particular an A-pillar turning vane, for guiding said airflow particularly advantageously and in a need-based manner.

The air guiding element 44 has a curved outer surface 50 which extends or is placed parallel to the corresponding A-pillar 24, in particular its outer surface 52. At least a portion 54 of the curved outer surface 50 of the air guiding element 44 faces towards the A-pillar 24, in particular its outer surface 52. As can be seen from Fig. 3, said portion 54 facing towards the outer surface 52 of the A-pillar 24 has a first curved shape, wherein the outer surface 52 facing towards the portion 54 of the outer surface 50 has a second curved shape corresponding to the first curved shape. Since there is a clearance between the portion 54 and the outer surface 52, the portion 54 and the outer surface 52 bound the through opening 48 acting as a turning vane being, for example, an external aero device configured to guide said airflow. The height and length of said external aero device, in particular the air guiding element 44 and/or the through opening 48, is optimized to effectively reduce the extent of flow separation while incurring minimal aerodynamic penalty of the device itself. Due to changes in the external surface on the A-pillar 24, the side door 38, and a transition from the side door 38 to a roof 60 of the cab 16, the extent of airflow separation around the A-pillar 24 can differ from top to bottom of the A-pillar 24 or 26 respectively. The height of the turning vane is optimized only to cover the section of the A-pillar 24 or 26 respectively where the air flow separation was observed. It was also found the length of the turning vane is also critical to preserve the aerodynamic benefit achieved from reducing the separation. The length of the turning vane is, for example, extended long enough to the point where the airflow of or through the turning vane itself starts to separate.

To achieve an attached airflow over the external surfaces 50 and 52 of the respective turning vane, which directly impacts the ability of the respective turning vane to stay at least drag neutral, the leading edge of the respective turning vane is shaped to naturally follow the stream lines primarily on the upper section of the device. The other contributing feature of the device that helps in reducing the airflow separation on the external surface is a cross-sectional radius of the leading edge. A generous radius of the leading edge cross-section which runs from lowest point to the top helps keep the airflow attached.

Said offset distance between the respective air guiding element 44 or 46 and the corresponding A-pillar 24 or 26 respectively at the leading edge and trailing edge is set in such a way that the flow between the respective air guiding element 44 or 46 and the corresponding A-pillar 24 or 26 respectively stays attached to the turning vane surface 50 and the surface 52 of the A-pillar 24 or 26 respectively. Said clearance between the air guiding element 44 and the corresponding A-pillar 24 is illustrated in Fig. 3. To preserve aerodynamic performance of the respective turning vane, the curvature of the air guiding element 44 and 46 is optimized to keep the flow attached to the outboard surface 52 and/or 50. Reduction and flow separation around the A-pillar 24 or 26 decreases aerodynamic drag for the vehicle thus improving fuel economy.

In the embodiment shown in Figs. 2 to 4, the air guiding element 44 is arranged on the passenger’s side of the commercial vehicle 10, wherein the air guiding element 46 is arranged on the driver’s side of the commercial vehicle 10. Fig. 3 shows a cross-section of said turning vane formed or bounded by the air guiding element 44 and the corresponding A-pillar 24, in particular the surfaces 50 and 52.

As commonly seen on a tractor, the extent of flow separation is amplified on the leeward side of the commercial vehicle in a side wind condition. The increase in flow separation is primarily due to increase in adverse pressure gradients across the leeward side of the A-pillar. The increase in adverse pressure gradients are primarily due to the fact that the air flow has to travel longer a distance around the A-pillar on the leeward side. The extent of the airflow separation increases with an increase in the side wind component. In such situations, said external aero device is most effective in reducing aerodynamic drag on the A-pillar when the commercial vehicle 10 experiences side wind conditions. External components attached to the cab 16, in particular the side door 38, like the respective exterior mirror 36, also influences the flow around the A-pillar by partially reducing the flow separation around the A-pillar 24 or 26 in the case of the respective exterior mirror 36 which is also referred to as a main mirror. To treat non-uniform flow separation around the respective A-pillar 24 or 26, the turning vane’s height and length are optimized to only be able to influence that part of the respective A-pillar 24 or 26 where the flow separation is observed. In a standard tractor trailer, the driver’s side and passenger’s side main mirrors are placed asymmetrically to the truck longitudinal axis to provide the most optimum visibility to the driver. As the mirror location and its proximity to the respective A-pillar 24 or 26 influences the flow separation, the asymmetry in the mirrors induces asymmetry across the driver’s side and passenger’s side in the extent of flow separation around the A-pillars 24 and 26. To achieve an optimum solution, the asymmetry in the flow separation requires a turning vane designed to be optimized to match the passenger’s side and driver’s side separately.

In the embodiment shown in Figs. 2 to 4, the respective air guiding element 44 or 46 is attached to the side door 38. For this purpose, the side door 38 comprises two mounting structures 56 and 58 as shown in Fig. 4. The two mounting structures 56 and 58 are used to realize a high stability and structural integrity. To ensure minimum impact on an aerodynamic drag from the mounting structures 56 and 58 for mounting the air guiding element 44, the cross-section of the respective mounting structures 56 ad 58 is profiled to match the flow direction of the flow between the air guiding element 44 and the A-pillar 24 through the turning vein. For example, the mounting structures 56 and 58 are mounted on the A-pillar 24 so as to attach the air guiding element 44 to the A-pillar 24 by means of the mounting structures 56 and 58. A method of reducing the flow separation around a corner using turning vanes as described in relation to Figs. 2 to 4 can also be applicable at other sections of the commercial vehicle 10. Fig. 5 shows a hood 60 and a bumper 62 of the commercial vehicle, the hood 60 and the bumper 62 being arranged at the front of the commercial vehicle 10. As can be seen from Fig. 5, respective air guiding elements 64 and 66 of the air guiding device 42 are arranged at respective sides 68 of the bumper 62 so that, for example, the bumper 62 is arranged between the air guiding elements 64 and 66 in the transverse direction of the vehicle. For example, the air guiding elements 64 and 66 have the same functions as the air guiding elements 44 and 46 so that respective turning vanes through which air can flow are bounded by the bumper 62 and the respective air guiding elements 64 and 66. Flence, in a side wind condition, the flow around the bumper 62 can experience higher adverse pressure gradients on the leeward side of the bumper 62 which can result in flow separation. For similar reasons as described in relation to the respective A-pillar 24 or 26, the flow around the bumper 62 experiences higher flow separations with an increase in side wind magnitudes. Similar to the described A-pillar turning vane, said bumper turning vanes bounded by the bumper 62 and the air guiding elements 64 and 66 can be implemented to help reduce flow separation to reduce aerodynamic drag in a side wind situation.

List of reference signs 10 commercial vehicle 12 trailer 14 frame 16 cab 18 hood 22 directional arrow 24 A-pillar 26 A-pillar 28 directional arrow 30 windscreen 32 directional arrows 34 directinal arrows 36 exterior mirror 38 side door 40 side window 42 air guiding device 44 air guiding element 46 air guiding element 48 through opening 50 outer surface 52 outer surface 54 portion 56 mounting structure 58 mounting structure 60 roo 62 bumper 64 air guiding element 66 air guiding element

Claims

1. An air guiding device (42) for a cab (16) of a commercial vehicle (10), the air guiding device (42) comprising at least one air guiding element (44) which, in at least one state of the air guiding element (44), overlaps at least a portion of an A-pillar (24) of the cab (16) and is arranged at a distance from the portion.

2. The air guiding device (42) according to claim 1, wherein at least a portion of an outer surface (50) of the air guiding element (44) is curved.

3. The air guiding device (42) according to claim 2, wherein the curved portion of the outer surface (50) of the air guiding elements faces towards the A-pillar (24) or away from the A-pillar.

4. The air guiding device (42) according to any one of the preceding claims, wherein the portion of the A-pillar (24) has a first outer surface (52) having a first shape, and wherein the air guiding element (44), at least in a portion, has a second outer surface (50) facing towards the first outer surface (52), the second outer surface (50) having a second shape corresponding to the first shape.

5. The air guiding device (42) according to any one of the preceding claims, wherein the air guiding device (42) comprises at least one second air guiding element (46) which, in at least one state of the second air guiding element (46), overlaps at least a portion of a second A-pillar (26) of the cab (16) and is arranged at a distance from the portion of the second A-pillar (26) being arranged opposite to the first A-pillar (24) in the transverse direction of the vehicle (10).