WO2014035299A1

WO2014035299A1 - Commercial vehicle with vortex generators

Info

Publication number: WO2014035299A1
Application number: PCT/SE2012/000127
Authority: WO
Inventors: Anders Tenstam; Fredrik EKROTH
Original assignee: Volvo Technology Corporation
Priority date: 2012-08-31
Filing date: 2012-08-31
Publication date: 2014-03-06

Abstract

The present invention relates to a commercial vehicle comprising an outer body having a frontal surface facing in a forward direction and which comprises a pair of front corner sections, which are provided with vortex generators adapted to direct a local flow of air along respective body sides, which flow of air is generated by forward motion of the vehicle, in order to reduce the drag of the vehicle by delaying flow separation. The present invention also relates to a method for manufacturing a driver's cab of a commercial vehicle.

Description

COMMERCIAL VEHICLE WITH VORTEX GENERATORS

Field of the Invention

The present invention relates to the field of aerodynamic properties of commercial vehicles, such as trucks and buses, and more specifically to controlling the flow of air across the outer body of commercial vehicles by utilizing vortex generators. The present invention also relates to a method for manufacturing a driver's cab of a commercial vehicle with vortex generators arranged on or integrated into the outer surface of the vehicle. Background Art

In the field of road transportation using commercial vehicles there is a continuous desire to increase the efficiency and propel the vehicles by fuel/energy as efficiently as possible. Thereby, the ratio between the distance traveled and amount of energy consumed may be improved. One key property is the drag coefficient associated with the aerodynamic effects on the vehicle during operation. Since aerodynamic drag increases with the square of speed, a reduction of the drag leads to an amplified improvement of fuel and/or energy efficiency.

For commercial vehicles such as trucks and buses, the drag from the aerodynamic effects is substantial due to the large surface area of the vehicle. In order to reduce the drag, the shape of the vehicle outer body may be made more stream-lined. However, the common basic structural designs of commercial vehicles have various design requirements that must taken into account, such as driver visibility requirements, driver comfort, living space, structural strength and stability of the vehicle outer body, government vehicle dimension regulations, as well as space optimization for e.g. the cab, engine compartment and load compartment. These requirements lead to vehicle designs with angular and abrupt outer body features which increase the large scale turbulence associated with flow separation, and the drag coefficient, thereby impeding the possibility of providing aerodynamically efficient commercial vehicles. Summary of the Invention

In view of the above-mentioned and other drawbacks of the prior art, a general object of the present invention is to provide improved aerodynamic properties and more efficient operation and fuel economy of commercial vehicles.

These and other objects are achieved by a commercial vehicle and a method for manufacturing a driver's cab of a commercial vehicle according to the independent claims. Preferred embodiments of the invention are presented in the dependent claims.

According to a first aspect thereof, the present invention relates to a commercial vehicle comprising an outer body having a frontal surface, such as a windshield or a grill, facing in a forward direction of the vehicle.

Furthermore, the outer body comprises a pair of vehicle front side corner sections arranged on opposite lateral sides of the frontal surface, and a pair of body sides extending from a respective side corner section, and/or a vehicle front top corner section forming an upper delimiting edge of the frontal surface, and a body roof extending from the top corner section, characterized in that the vehicle front side corner sections and/or the vehicle front top corner section are/is provided with vortex generators arranged to affect a local flow of air across the corner sections, which flow of air is generated by forward motion of the commercial vehicle a pair of vehicle front corner sections arranged on opposite lateral sides of the frontal surface, The vortex generators efficiently reduce the drag coefficient of the commercial vehicle by reducing the tendency of flow separation associated with the flow of air across the lateral side corner section of the frontal surface of the vehicle or across the top corner section. In more detail, the relatively square-shaped frontal ends of commercial vehicle with sharp lateral side corner sections between the frontal surface and the lateral sides and between the frontal surface and the body roof prevents the flow of air to stay attached to the flow surface of the outer body of the vehicle such that it instead separates and creates aerodynamic losses. By providing the vortex generators, the air flow boundary layer is energized such that the flow may stay attached to the surface in an improved manner. The vortex generators generate vortices in the flow of air by forcing the flow of air to fall into a swirling motion, wherein the vortices extend along the lateral sides of the outer body, such that large scale turbulence associated with flow separation advantageously may be reduced. In turn, the vehicle drag during operation is reduced

For example, for corner sections having a curvature, i.e. not having a shaft corner profile, the vortex generator effectively delay separation for a case when the flow is just beginning to separate, such as when the radius of the corner section, or the radius equivalent shape of the curvature of the corner section, is under-critical for the flow situation.

The vortices are generated by the introduction of a pressure difference between the two sides of the vortex generators in the flow of air, thereby causing the flow to fall into a spiraling motion, with the vortex core being essentially parallel with the main flow direction.

Also, the improved air flow pattern without flow separation provided by the vortex generators may help to reduce soiling of the later side windows and reduce entrainment of dirt particles from the surroundings.

The invention is based on the realization by the inventors that considerably improved aerodynamic efficiency of a commercial vehicle may be provided with reduced restrictions on outer body design criteria of the vehicle, such as driver comfort, structural strength and stability of the vehicle outer body, government dimension regulations, as well as space optimization for e.g. the cab, engine compartment and load compartment, by providing the corner section with vortex generators. However, since the formation of the spiraling motion of the flow itself will absorb some energy from the flow, a net gain in energy, in this case manifested as body drag, will be realized only for those cases where the flow would elsewise separate from the surface when no vortex generators would be attached.

According to an exemplifying embodiment, a plurality of vortex generators are provided on outer flow surfaces of each corner section, wherein each vortex generator extends outwardly or inwardly from the respective flow surfaces of the vehicle front corner sections. Thereby, an improved flow pattern with reduced drag may advantageously be provided along each corner section. According to a further exemplifying embodiment, the vortex generators comprise a fin-shaped body having an inner edge and an outer edge, wherein each vortex generator is attached at, or on, the respective corner sections at the inner edge. Thereby the vortex generators extend outwardly from the flow surface. Optionally or alternatively, the vortex generators are, according to an exemplifying embodiment, inwardly oriented vortex generators formed of triangular-shaped recesses extending into the corner section/sections.

Moreover, the outer edge of each vortex generator may be arranged freely in the flow of air, wherein the vortex generators are separately arranged in relation to each other with a free outer edge which is not connected to adjacent vortex generators or to the outer body of the vehicle. This allows for generation of vortices in an advantageous manner, while allowing for minimal interference and disturbance of the air flow adjacent the outer body surface during operation.

According to an exemplifying embodiment, each vortex generator has a height, in the case of outwardly protruding vortex generators, or a depth, in the case of inwardly protruding vortex generators, corresponding to a thickness, e.g. within an order of magnitude, of the boundary layer of the local air flow, which allows the vortex generator to affect the boundary layer in a improved manner. For example, the boundary layer thickness may be defined as the average thickness of the boundary layer at the position of each vortex generator during normal average driving conditions, for example when driving at normal average cruising speeds, e.g. between 80 (EU) and 120 (US) km/h. The boundary layer properties, such as thickness, may also depend of the configuration and shape of the frontal surface of the vehicle body.

According to an exemplifying embodiment, the height of the vortex generator is between 1 and 50 mm, or between 2 and 30 mm or between 2 and 15 mm. The height of the vortex generator, i.e. the height of the protrusion of the vortex generator, may e.g. be defined as the maximum length between the inner edge and a free outer edge of the vortex generator in a direction orthogonal to the flow surface of the corner section at which the vortex generator is positioned.

According to an exemplifying embodiment, the length of the vortex generator is between 2 and 75 mm, or between 3 and 50 mm, or between 5 and 30 mm. The length may e.g. be defined as the length of the vortex generator in a direction coinciding with the inner edge of the vortex generator, or the length may be defined as the length of the inner edge of the vortex generator.

According to an exemplifying embodiment, each vortex generator further comprises control surfaces arranged on opposite side of the vortex generator body for directing the flow of air. The control surfaces may be flat surfaces or slightly curved surfaces and are arranged to affect the flow of air to generate vortices. The control surface may further be rigid, or non-flexible.

According to an exemplifying embodiment, the vortex generators are inclined with respect to the local flow of air. In other words, the vortex generators are positioned obliquely so that they have an angle of attack with respect to the local airflow, or in relation to the forward direction of the vehicle. According to a further exemplifying embodiment, the vortex generators are formed of a plurality of pairs of vortex generators, each pair comprising two vortex generators being inclined in opposite direction and/or angles in relation to each other.

According to an exemplifying embodiment, the frontal surface is formed by a frontal windshield of the vehicle, wherein the pairs of front side corner sections are arranged adjacent respective lateral edges of the frontal windshield. For example, the pair of vehicle front side corner sections forms a pair of A-pillars, also referred to as front corner A-posts, of the commercial vehicle. The side corner sections may also comprise front side corner sections below the windshield, e.g. in level with the grill or headlight of the vehicle.

According to an exemplifying embodiment, the vehicle front side corner sections are vertical, or substantially vertical. For example, for a commercial vehicle, the front corner sections may be tilted a tilt angle in relation to a vertical axis not exceeding 30 degrees, or 20 degrees, or 10 degrees, or 5 degrees. The tilt angle may for example be defined in a tilting direction around a horizontal transverse axis extending between the lateral sides of the vehicle orthogonally to the forward direction of the vehicle. According to an

embodiment, the vehicle front top corner section is horizontal, or substantially horizontal.

According to a further exemplifying embodiment, each respective flow surface of the corner sections comprises a bent portion extending at least partially from the frontal surface to respective body side or from the frontal surface to the body roof, wherein the vortex generators are arranged on the respective bent portions, or within one equivalent bend radius upstream of the bent portion. For example, the bent portion forms the flow surface of the respective corner section. According to various embodiments, the radius of curvature of the bend portion of the respective corner sections may be between 50 and 300 mm. According to an embodiment, the bent portions of the corner sections are formed by a cover element which may be secured to the vehicle body framework, such as a sheet metal framework in the body in white (BIW) vehicle manufacturing stage, at the corner sections. Advantageously, the vortex generators may, according to an embodiment, be integrally formed in cover elements which may be secured to the vehicle body framework, wherein the cover elements form the outer delimiting surface of the vehicle body at the respective corner sections. Thereby, the configuration of the vortex generators may be changed by replacing the cover elements to different cover elements with vortex generators of different size, shape, orientation with regards to each other, and/or angle of attack, etc., in order to adapt the vortex generator's geometry and properties to different vehicle operation conditions, such as average driving speed, depending on the intended use of the vehicle.

The vortex generator may, according to various embodiments, have different shapes, such as triangular, rectangular, circular or semi-circular, or be trapezoid-shaped, or a combination of these.

For example, the commercial vehicle is a truck (lorry) or a bus, such as heavy and/or medium type truck or bus. For example, a heavy vehicle, such as a truck, large goods vehicle or bus, may e.g. have driving vehicle weight, or authorized mass, more than 3000 kg.

According to an exemplifying embodiment, the vortex generators on the respective corner section are aligned in a row extending along a main direction of extension of the corner section. For example, according to various embodiments, the lateral distance between the pairs of vortex generators is typically in the order of one or more vortex generator lengths, measured in the longitudinal direction. Each corner section may be provided with one row, or only one row, of vortex generators.

According to an exemplifying embodiment, each vortex generator is arranged to increase the longitudinal vorticity in the flow of air following the vortex generator. Thereby, the flow separation of the air flow from the vehicle body is moved rearwards in relation to the forward direction of the vehicle which reduced the drag coefficient Co of the vehicle. In more detail, by delaying flow separation the large scale turbulence associated with flow separation may be reduced, which, in turn, reduces vehicle drag during operation. According to an embodiment, the outer body of the vehicle is delimited, in the forward direction of the vehicle, by the frontal surface.

According to a further aspect thereof, the present invention relates to a method for manufacturing a driver's cab of a commercial vehicle, which cab comprises an outer body having frontal surface facing in a forward direction of the cab, wherein the outer body has a pair of cab front side corner sections arranged on opposite lateral sides of the frontal surface and a pair of body sides extending from a respective side corner section, and/or wherein the outer body has cab front top corner section forming an upper delimiting edge of the frontal surface and a body roof extending from the top corner section. Furthermore, the method comprises providing the corners sections with vortex generators arranged to generate vortices in the flow of air moving across the corner sections. The method is advantageous in that an improved commercial vehicle cab is provided having improved aerodynamic properties. The commercial vehicle cab provided by the method is further advantageous in similar manners as described in relation to the first aspect of the invention.

The outer body of the cab may also be delimited, in the forward direction of the cab, by the frontal surface.

Generally, other objectives, features, and advantages of the present invention will appear from the following detailed disclosure, from the attached dependent claims as well as from the drawings are equally possible within the scope of the invention.

Brief Description of Drawings

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein:

Fig. 1 is a schematic perspective view of an embodiment of the commercial vehicle provided with vortex generators according to the present invention.

Fig. 2a is a zoomed-in schematic perspective view of the vortex generators according to an embodiment of the present invention.

Fig. 2b is a zoomed-in schematic perspective view of the vortex generators shown in Fig. 2a, from a different angle. Fig. 3 is a schematic top view, seen in a direction orthogonal to the body surface, of the vortex generators according to an embodiment of the present invention.

Figs. 4a-j are schematic side views of alternative embodiments of the vortex generators according to the present invention.

Fig. 5 is a schematic chart illustrating accumulated (along x-axis) drag coefficient Co values for an exemplifying commercial vehicle, wherein the x- axis represents the longitudinal direction of the exemplifying commercial vehicle.

Fig. 6 is a schematic perspective view of a pair of vortex generators and generated vortices according to an embodiment the present invention.

Figs. 7a-b are schematic side views of alternative embodiments of inwardly extending vortex generators according to the present invention. It should be understood that the drawings are not true to scale and, as is readily appreciated by a person skilled in the art, dimensions other than those illustrated in the drawings are equally possible within the scope of the invention. Detailed Description of Embodiments of the Invention

In the drawings, corresponding, or equal elements are referred to by equal reference numerals.

In Fig. 1 , a schematic perspective view of an embodiment of a commercial vehicle 1 provided with vortex generators 6 according to the present invention is shown. As illustrated, the exemplifying commercial vehicle 1 comprises a semi-trailer and a flat nose truck, wherein the truck unit, or tractor, comprises an outer body 2 which is delimited by a frontal surface facing in a forward direction of the vehicle. The frontal surface is formed of the frontal surfaces 3 constituting the windshield and frontal surface 3'

constituting the grille of the commercial vehicle 1. The outer body 2 of the vehicle comprises a pair of vehicle front side corner sections 4a and 4b arranged on opposite lateral sides of the frontal surface 3 and 3', and a pair of body sides 5a and 5b extending rearwards along the commercial vehicle 1 from the respective side corner sections 4a and 4b. The body 2 further comprises a vehicle front top corner section 4c forming an upper delimiting edge of the frontal surface 3, wherein a body roof 5c extends rearward along the commercial vehicle 1 from the top corner section 4c. Each one of the corner sections 4a, 4b and 4c comprises a respective flow surface 4'a, 4'b, and 4'c across which a flow of air generated during motion of the vehicle flows. In more detail, each flow surface 4'a, 4'b, and 4'c is formed of a bent portion 8 having a curve profiled, having a radius of curvature as e.g.

indicated by 8', wherein the respective bent portions of the side corner sections 4a and 4b, extends at least partially from the frontal surfaces 3 and 3' to the respective body sides 5a and 5b, and wherein the bent portion of the top corner section 4c extends at least partially from the frontal surface 3 to the body roof 5c.

As further shown, the corner sections 4a, 4b, and 4c are provided with a plurality of vortex generators 6 which are separately arranged in relation to each other along the main direction of extension of the respective corner sections 4a, 4b and 4c. During operation, wherein the vehicle is moving in relation to the surrounding air, the vortex generators 6 energize the air flow boundary layer by creating vortices, such as vortices 7a and 7b, wherein the air fall into a swirling motion, as illustrated, which results in that the flow of air stays attached to the surfaces of the body sides 5a, 5b and the surface of the body roof 5c in an improved manner. As shown in the exemplifying

embodiment, the vortex generators 6 are arranged substantially in a center position between the frontal surface and the body sides 5a, 5b and body roof 5c on the respective flow surfaces 4'a, 4'b, and 4'c of the corner sections 4a, 4b, and 4c. However, the vortex generators 6 may also be arranged on a forward portion of the respective flow surfaces 4'a, 4'b, and 4'c, i.e. more upstream, in relation to the forward direction of the vehicle. The vortex generators may also be arranged at the corner sections 4a, 4b, and 4c within approximately one, or within two, bending radii upstream of a forward edge of their respective bent portion 8. Furthermore, the vortex generators 6 can be arranged on a rearward portion, in relation to the forward direction of the vehicle, of the respective flow surfaces 4'a, 4'b, and 4'c.

With reference to Fig. 1 , the vortex generators are schematically illustrated and may be formed of outwardly and/or inwardly, in relation to the flow surface where the respective vortex generators are located, protruding vortex generators. As further shown, the vortex generators 6 are aligned in relation to each other in pairs substantially pointing the forward direction of the vehicle.

With reference to Figs. 2a and 2b, outwardly protruding vortex generators 6 according to an embodiment of the present invention are schematically shown in zoomed-in schematic perspective views from different angles. The vortex generators 6 are arranged in separately positioned vortex generator pairs 6', each pair 6' forming vortices 7a and 7b traveling rearwards across the remaining rearward portion of the flow surface 4'a of the side corner section 4a and into the region adjacent the surface of the body side 5a. The configuration of the vortex generators 6, as described with reference to Figs. 2a and 2b is also applicable in a corresponding manner to vortex generators arranged at or on the flow surfaces of 4'b of side corner section 4b and the flow surface 4'c of the top corner section 4c, described with reference to Fig. 1.

In Fig. 3, a schematic view in orthogonal direction from the body surface of two vortex generator pairs according to an embodiment of the present invention is shown. Each vortex generator pair comprises two vortex generators 6 arranged in an inclined configuration in relation to each other, wherein the distance between their forward, or leading, edges, 6c is closer than the distance A1 between their rearward, or trailing, edges 6d, in relation to the forward direction of the vehicle and/or the direction of the flow of air generated when the vehicle is travelling in its forward direction. As further shown, each vortex generator pair comprises control surfaces 9a and 9b arranged on opposite side of the vortex generator body for directing the flow of air.

According to an exemplifying embodiment, the distance A1 between the rearward edges 6d corresponds, or is in the same order of magnitude, as the longitudinal length of the vortex generators. Optionally, or alternatively, the distance A1 between the rearward edges 6d is about 25 mm or within ± 10 mm of 25 mm, the distance A3 between the separate vortex generators pairs is about 10 mm or within ± 5 mm of 10 mm. According to a further embodiment, the tilt angles A2 are about 20 degrees or within ± 10 degrees of 20 degrees. According to a further embodiment, every other vortex generator pair is removed, such that the distance between each pair is increased by a distance corresponding to A1 +A3.

In Figs. 4a-j, schematic side views of alternative embodiments of outwardly extending fin-shaped vortex generators are shown. Each vortex generator has a longitudinal length, as indicated by B1 in Fig. 4a. The longitudinal length of the vortex generator coincides with inner edge 6a of the vortex generator embodiments shown in Figs. 4a, 4c, 4d, 4f, 4g, 4i, wherein the longitudinal length of the vortex generator embodiments shown in Fig. 4e and Fig. 4j exceeds the length of the inner edge 6a. As illustrated, the vortex generators have a height H, define as e.g. shown in Fig. 4a and an outer edge 6b, as e.g. shown in Fig. 4b illustrating a rectangular vortex generator. The vortex generators may also have an inclined forward, or leading, edge portion 6e, as illustrated in e.g. Figs. 4c and 4h. The inclined forward portion 6e may also have a curved shaped and conform with the outer edge of the vortex generator, as shown in e.g. Fig. 4d illustrating a vortex generator having a half-circle shape and Fig. 4e illustrating a vortex generator having the shape corresponding to a sectional portion of an oval. Furthermore, the vortex generator may have a triangular shape as shown in Figs. 4a and 4f, or a trapezoid shape as shown in Figs. 4i and 4j.

With reference to Fig. 5, a schematic chart is illustrating different accumulated predicted values for the drag coefficient C_D for a commercial vehicle along its length of extension represented by the x-axis. As shown, the drag coefficient CD is given for two different cases: (i) without vortex generators according to the present invention as indicated by a dashed line, and (ii) with vortex generators arranged according to a first embodiment of the present invention as indicated by a dotted line.

As indicated in the chart, the accumulated value of CQ, given by the respective end points for the different lines of the different cases (x = 1), is reduced by approximately 3.3 % for the second case (ii) in relation to the first case (resulting in a noticeable reduction in fuel consumption approximately corresponding to about 1 % calculated on a typical European long haul duty cycle. On a U.S. highway cycle this would correspond to a fuel consumption reduction of about 1.5%. As is clear from the chart, the aerodynamic properties of the commercial vehicle provided with vortex generators according to present invention is improved as the flow of air across the corner sections of the frontal surface of the vehicle better follows the geometry of the body of the vehicle. The high peak, approximately between x = 0.15 and x = 0.18, is formed by the opening between the vehicle cab and trailer, and the end peak, x = 1 , is formed by the low pressure directly formed behind trailer of the vehicle.

In Fig. 6, a schematic perspective view of a vortex generator pair 6' according to an embodiment the present invention is shown, which pair comprises outwardly extending triangular vortex generators 6. Each vortex generator is attached by its respective inner edge 6a to the flow surface, and is arranged in an inclined configuration in relation to each other and in relation to a schematically illustrated air flow, such that each vortex generator 6 has an angle of attack in relation to the local air flow at the position of the vortex generator. Each vortex generator further comprises a forward edge 6c, a rearward edge 6d, and control surfaces 9a and 9b arranged on opposing sides of each vortex generator. As illustrated, the vortex generators 6 create a respective schematically illustrated vortex 7a and 7b, each which are arranged to draw energetic more rapidly-moving air from outside a slower moving boundary layer closer to the surface of the outer body of the vehicle, which, in turn, results in a reduction of large scale turbulence associated with flow separation.

The vortices 7a and 7b are generated by the introduction of a pressure difference between the two control surfaces 9a and 9b of the respective vortex generator in the flow of air, thereby causing the flow of air to fall into a spiraling motion, with the vortex core being essentially parallel with the main flow direction. With increasing distance from the vortex generators 6 in the downstream direction, i.e. away from the rearward edge 6d of the vortex generators, the swirling motion and energy in the vortices reduces. The vortex generators 6 are therefore suitably placed upstream of and sufficiently close to the point at which the flow of air separates from the outer body of the vehicle in order to ensure that vortices 7a and 7b may effectively reduce the flow separation. In Figs. 7a-b, schematic perspective views of alternative embodiments of inwardly extending vortex generators 6 according to the present invention are shown. The vortex generators 6 are formed of inwardly extending voids which are formed in the outer surface of the vehicle body, more specifically on a corner section 4 of a commercial vehicle in a similar manner as describe with reference to Figs. 1 and 2a-b. During operation, the flow of air e.g. enters at a forward, or leading, entry portion 6f of each vortex generator 6 and travels into the inward opening in the flow surface 4 formed by each vortex generator 6. At the later sides of each vortex generator 6, the flow of air is forced into a swirling motion by and around a control portion 6g forming part of the inward structure forming the vortex generator 6. The swirling motion of the flow of air results in similar effects as described above in relation to outwardly extending vortex generators. The vortices are generated by the formation of pressure difference on different sides of the control portions 6g, thereby causing the flow to fall into a spiraling motion, with the vortex core being essentially parallel with the main flow direction.

As further shown, each one of the exemplifying embodiments of the inwardly extending vortex generators 6 has a substantially triangular shape having a tip at the entry portion 6f, wherein vortex generators 6 are arranged on or at the corner sections of the vehicle such that the entry portion 6f is pointing into the flow of air generated by the forward motion of the commercial vehicle during operation. The vortex generator 6 shown in Fig. 7a further comprises a replaceable cover element forming an internal control surface of vortex generator, which cover element is inserted in an opening in the corner section 4 and attached to e.g. an internal support structure of the vehicle frame (not shown) inside the corner section 4.

It should be noted that the invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims. Considering references to the position and

orientation of features in relation to the vehicle or the cab of the vehicle, including such terms as upper and lower, those terms are intended to have their normal meaning as defined when the vehicle or cab are oriented in their normal position during e.g. normal driving on a road.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single apparatus or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain features or method steps are recited in mutually different dependent claims does not indicate that a combination of these features or steps cannot be used to advantage.

Claims

1. A commercial (1) vehicle comprising an outer body (2) having a frontal surface (3) facing in a forward direction of the vehicle, which outer body comprises:

- a pair of vehicle front side corner sections (4a, 4b) arranged on opposite lateral sides of the frontal surface, and a pair of body sides (5a, 5b) extending from a respective side corner section, and/or

- a vehicle front top corner section (4c) forming an upper delimiting edge of the frontal surface, and a body roof (5c) extending from the top corner section,

characterized in that the corner sections (4a, 4b; 4c) are provided with vortex generators (6) arranged to affect a local flow of air across the corner sections, which flow of air is generated by forward motion of the commercial vehicle.

2. The commercial vehicle (1) according to claim 1 , wherein a plurality of vortex generator (6) are provided on respective flow surfaces (4'a, 4'b; 4'c) of each corner section (4a, 4b; 4c), wherein each vortex generator extends outwardly and/or inwardly from the respective flow surfaces of the vehicle front corner sections (4a, 4b; 4c).

3. The commercial vehicle (1) according to any one of the preceding claims, wherein the vortex generators (6) comprise a fin-shaped body having a an inner edge (6a) and an outer edge (6b), wherein each vortex generator is attached at the respective corner sections (4a, 4b; 4c) at the inner edge (6a).

4. The commercial vehicle (1) according to any one of claims 1-2, wherein the vortex generators (6) are inwardly oriented vortex generators formed of triangular-shaped recesses extending into the corner section (4a, 4b; 4c).

5. The commercial vehicle (1) according to any one of the preceding claims, wherein each vortex generator has a height or depth corresponding to a thickness of the boundary layer of the local air flow.

6. The commercial vehicle (1) according to any one of the preceding claims, wherein the height or depth of the vortex generator is between 2 and 50 mm.

7. The commercial vehicle (1) according to any one of the preceding claims, wherein the vortex generators are inclined with respect to the local flow of air.

8. The commercial vehicle (1) according to any one of the preceding claims, wherein the frontal surface (3) is formed by a frontal windshield of the vehicle, and

wherein the pair of front side corner sections (4a, 4b) are arranged adjacent respective lateral edges of the frontal windshield (3).

9. The commercial vehicle (1 ) according to any one of the preceding claims, wherein the pair of vehicle front side corner sections (4a, 4b) forms a pair of A-pillars of the commercial vehicle.

10. The commercial vehicle (1) according to any one of the preceding claims, wherein the vehicle front side corner sections (4a, 4b) are vertical, or substantially vertical, and/or

wherein the vehicle front top corner section (4c) is horizontal, or substantially horizontal.

11. The commercial vehicle (1) according to claim 2, wherein each respective flow surface (4'a, 4'b; 4'c) of the corner sections (4a, 4b; 4c) comprises a bent portion (8) extending at least partially from the frontal surface (3, 3') to respective body side (5a, 5b) and/or from the frontal surface (3) to the body roof (5c), wherein the vortex generators are arranged on the respective bent portions or within one bending radius upstream of the bent portion.

12. The commercial vehicle (1) according to any one of the preceding claims, wherein the vortex generators (6) on the respective corner section (4a, 4b; 4c) are aligned in a row extending along a main direction of extension of the corner section.

13. The commercial vehicle (1) according to any one of the preceding claims, wherein each vortex generator is arranged to increase the longitudinal vorticity in the flow of air following the vortex generator.

14. Method for manufacturing a driver's cab of a commercial vehicle, which cab comprises an outer body (2) having a frontal surface (3) facing in a forward direction of the cab,

- wherein the outer body has a pair of cab front side corner sections (4a, 4b) arranged on opposite lateral sides of the frontal surface, and a pair of body sides (5a, 5b) extending from a respective side corner section, and/or

- wherein the outer body has cab front top corner section (4c) forming an upper delimiting edge of the frontal surface, and a body roof (5c) extending from the top corner section,

which method is characterized by providing the corners sections (4a, 4b; 4c) with vortex generators arranged to generate longitudinal vortices in the flow of air moving across the corner sections.