WO2018160017A1 - Biomimetic air drag reduction device for freight vehicle - Google Patents

Abstract

The present disclosure relates to an air drag reducing device for a freight vehicle for reducing air drag of a freight vehicle including a tractor and a trailer, the device comprising: a main body coupled to a roof of the tractor and including a streamlined curved surface; an air flow changing part protruding from the main body part to form a first curved surface and changing the flow of air flowing along the main body part on the roof of the tractor; an air flow control part protruding from the main body part to form a second curved surface having a curvature different from the curvature of the first curved surface and connected to the air flow changing part to control the air flow; and an extension part extending from the main body toward the ground and coupled to a rear surface of the tractor to partially or wholly block a space between the tractor and the trailer.

Description

Biomimetic air resistance reduction device for vans

The present disclosure relates to a biomimetic air resistance reduction apparatus for a van.

Countries around the world are actively developing related technologies to reduce fuel costs, which account for the largest proportion of logistics costs incurred in transportation. Among these, freight cost reduction of 70% (ton-km basis) of freight vehicles is very profitable compared to the cost of technology development, and helps to reduce GHG emissions while preparing for high oil prices.

In foreign countries, we are actively pursuing R & D certification, promotion and support projects for air vehicle resistance reduction devices. On the other hand, in Korea, the development of related technologies is in its infancy, and most of the commercially available air resistance reduction devices mimic the shape without optimization verification of the attached vehicle. In accordance with the domestic and international situation, the air resistance reduction device that delays the flow separation occurring in the space between the front part of the tractor and the tractor-trailer and suppresses the generation of vortices by using a unique technology reduces air resistance and reduces fuel costs. To reduce the

The substrate is coupled to the driver's cab roof of the tractor trailer to effectively control the flow separation and vortex flow inside the space between the tractor front and the tractor trailer to reduce air resistance. It is to provide a biomimetic air resistance reduction device for a truck.

In addition, the technical problem to be solved by the present invention is not limited to the above-mentioned technical problem, and other technical problems not mentioned are clearly to those skilled in the art from the following description. Can be understood.

An apparatus for reducing air resistance for a van according to an embodiment of the present invention is to reduce the air resistance of a van including a tractor and a trailer, and is coupled to the roof of the tractor and includes a body having a streamlined curved surface. An air flow changing part protruding from the main body part to form a first curved surface and changing a flow of air flowing along the main body part on the roof of the tractor, and a curvature of the first curved part protruding from the main body part; A second curved surface having a different curvature and connected to the air flow changing part to control the flow of air and extending from the main body toward the ground to be coupled to the rear of the tractor to connect the tractor and the And an extension that blocks some or all of the space between the trailers.

In this case, the length of the body portion may be the same as the length of the tractor and the length of the extension portion.

The length of the extension may be at least 40% and at most 80% of the length between the tractor and the trailer.

On the other hand, the body portion front width is the same as the width of the tractor, the body portion rear width may be the same as the width of the trailer.

In this case, the deflection angle measured while matching the center of the main body front width and the main body rear width may be greater than 0 ° and 10 ° or less.

The height of the trailer may be equal to the sum of the height of the tractor and the height from the bottom of the body portion to the highest point of the air flow control.

The air resistance reduction apparatus for a van of the present embodiment, one end is coupled to the air flow control, the other end is further coupled to the tractor further includes a first fixed frame for fixing the air resistance reduction apparatus for a van to the tractor. can do.

At this time, the air resistance reduction device for a van of the present embodiment, one end is coupled to the extension portion, the other end is coupled to the tractor and the second fixed frame and the first fixed frame for fixing the extension to the tractor and It may further include a connecting frame for connecting and supporting the second fixed frame.

The extension may have a bellows shape or may be hinged to the rear of the tractor.

The extension end may further include a pattern portion, wherein the pattern portion may have a sinusoidal shape.

The extension portion may further include a vortex generating portion projecting outward from the surface of the extension portion.

According to the present disclosure, by effectively controlling the flow separation occurring in the space between the tractor front and the tractor and the trailer, the recirculation region and turbulent kinetic energy formed in the space between the tractor and the trailer can be reduced. Can be. In addition, not only the air flow passing through the top of the tractor, but also the control unit may further control the flow generated in the space between the tractor's side and the tractor and the trailer by further including an extension to improve driving stability with additional drag reduction effect. The effect can be obtained.

Figure 1 (a) is a view showing a van equipped with the air resistance reduction device for a van of the present invention.

Figure 1 (b) is a view showing a device for reducing air resistance according to the first embodiment of the present invention.

1 (c) is a view showing the air resistance reduction device for a van according to a second embodiment of the present invention.

2 is a view schematically showing a device for reducing air resistance of a van according to a first embodiment of the present invention.

3 is a view schematically showing a device for reducing air resistance of a van according to a second embodiment of the present invention.

4 is a view showing in detail some components included in the air resistance reduction apparatus for a freight vehicle according to an embodiment of the present invention.

5 is a view showing a modified example of the air resistance reduction device for a van of the present invention, respectively.

6 is a view schematically illustrating a folding process of an extension part having a bellows shape according to a modification of the present invention.

7 is a view schematically illustrating a folding process of an extension part folded by a hinge according to another modification of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing the present disclosure, description of already known functions or configurations will be omitted for clarity of the gist of the present disclosure.

Parts not related to the description are omitted in order to clearly describe the present disclosure, and like reference numerals designate like elements throughout the specification. In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, so the present disclosure is not necessarily limited to the illustrated.

1 is a view showing a first embodiment and a second embodiment of a vane air resistance reduction device 100 mounted on a van and a van equipped with a vehicle air resistance reduction device 100 of the present invention.

More specifically, Figure 1 (a) is schematically shown a van to which the air resistance reduction device 100 for a van according to the present invention is coupled. Referring to Figure 1 (a), the truck is coupled to the air vehicle resistance reduction apparatus 100 of the present invention, the driver including the driver's seat on board the truck, the tractor 10 having a roof covering the driver's seat and The trailer 20 is connected to the tractor 10 to transport the cargo. However, this is only an example shown to help the understanding of the present invention, and the truck to which the air resistance reduction apparatus 100 of the present invention is coupled must include a tractor 10 and a trailer 20. no.

Figure 1 (b) is shown the air resistance reduction apparatus 100 for a van according to the first embodiment of the present invention, Figure 1 (c) is shown in Figure 1 (c) air resistance for the van according to the second embodiment of the present invention Device 100 is shown. These are divided according to the specific shape of the extension 140, which will be described in more detail later.

Referring to Figure 1 (b) and Figure 1 (c), the air resistance reduction apparatus 100 for a van of the present invention is the body portion 110, air flow change unit 120, air flow controller 130 And an extension 140.

The main body 110 is coupled to the upper surface of the tractor 10 of the truck, that is, the roof of the tractor 10, has a surface made of a streamlined curved surface to reduce the resistance of the air when the truck is running. A detailed shape of the main body 110 will be described in detail later with reference to FIG. 4.

The air flow changing unit 120 protrudes from the main body 110 to form a first curved surface, and changes the flow of air flowing along the streamlined main body 110 on the roof of the tractor 10.

The air flow controller 130 protrudes from the main body 110 to form a second curved surface having a curvature different from that of the first curved surface. The air flow controller 130 is connected to the air flow changing unit 120 to change the air flow changing unit 120. By controlling the air whose flow is changed.

At this time, the air flow change unit 120 and the air flow controller 130 of the present embodiment are designed to mimic the shape of the head of the sea lion, it is possible to more effectively control the resistance due to the flow of the fluid. Detailed shapes of the air flow changing unit 120 and the air flow control unit 130 will be described later with reference to FIG. 4.

According to the present exemplary embodiment, the air flow is changed by the air flow changing unit 120, and the air flow control unit 130 guides it to the outside of the truck by the tractor 10 and the trailer 20 of the truck. It is possible to effectively control the flow separation generated in the space. Therefore, it is possible to greatly reduce the recirculation region and the turbulent kinetic energy generated in the space between the tractor 10 and the trailer 20 of the van.

Extension portion 140 is formed extending from the body portion 110 toward the ground, is coupled to the rear of the tractor 10 to block some or all of the empty space between the tractor 10 and the trailer (20). 1B and 1C, extensions 140 having different shapes are shown. These are shown to block only a part of the space between the tractor 10 and the trailer 20, but is not limited to this, and a modification to block all of the space between the tractor 10 and the trailer 20 is possible.

When the extension unit 140 is included, such as the air resistance reduction device 100 for a van of the present invention, the side portion of the tractor 10 and the tractor 10 are not controlled only by the flow of air flowing through the upper surface of the van. And the flow occurring in the space between the trailer 20 can also be controlled. Therefore, the air resistance can be more effectively controlled and reduced.

2 is a view schematically showing a device for reducing air resistance 100 for a van according to the first embodiment of the present invention, as shown in FIG. 1B, and FIG. 3 is as shown in FIG. 3 is a view showing an air resistance reduction apparatus 100 for a van according to a second embodiment of the present invention. Referring to FIGS. 1B and 2, an extension 140 having a shape in which only a part of the height of the tractor 10 is blocked and the height gradually decreases inversely from the tractor 10 toward the trailer 20 is provided. Is shown. Referring to FIGS. 1C and 3, an extension portion 140 having a predetermined height is shown to block all the heights of the tractor 10 and move toward the trailer 20 from the tractor 10. .

As shown in FIGS. 2 and 3, even if the extension 140 has any shape, similar functions and effects may be exhibited. Therefore, the extension unit 140 according to the present embodiments is coupled to the rear surface of the tractor 10, so that the air resistance reduction device 100 for the van can be more firmly and stably combined with the van. In addition, as described above, it is possible to control the flow generated in the space between the side portion of the tractor 10 and the tractor 10 and the trailer 20 by the extension 140.

Meanwhile, referring to FIG. 2, the air resistance reduction apparatus 100 for a van according to the first embodiment of the present invention may further include a first fixing frame 150. One end of the first fixed frame 150 is coupled to the air flow control unit 130 and the other end is coupled to the tractor 10 to fix the air resistance reduction apparatus 100 for the van to the tractor 10. According to the first embodiment of the present invention illustrated in FIG. 2, one end of the first fixed frame 150 is illustrated as being coupled to the air flow controller 130, but this is only an example and the first fixed frame ( If 150 is disposed between the vane air drag reduction device 100 and the tractor 10 to improve the fixing force therebetween, even if coupled to any configuration of the vane air drag reduction device 100 It will not limit the scope of implementation.

The air resistance reduction apparatus 100 for a freight vehicle according to the second embodiment of the present invention illustrated in FIG. 3 further includes a second fixing frame 160 and a connection frame 170 in addition to the first fixing frame 150. Since the first fixing frame 150 according to the second embodiment of the present invention includes one end coupled to the air flow controller 130 and the other end coupled to the tractor 10 is the same as described above, the overlapping description will be made. It will be omitted.

One end of the second fixed frame 160 according to the second embodiment of the present invention is coupled to the extension portion 140, and the other end of the second fixed frame 160 is coupled to the tractor 10 to extend the ( 140 is fixed to the tractor (10). 3 shows a total of four second fixed frames 160 formed in a pair on the left side and a pair on the right side of the rear surface of the tractor 10. As shown in FIG. 3, when the plurality of second fixing frames 160 are installed, the fixing force between the extension 140 and the tractor 10 may be further improved.

The connection frame 170 connects between the first fixed frame 150 and the second fixed frame 160 to support the first fixed frame 150 and the second fixed frame 160. As shown in FIG. 3, when the plurality of second fixing frames 160 are positioned on the left and right sides of the rear surface of the tractor 10, as shown in FIG. One end of the fixing frame 150 and one end of the plurality of second fixing frames 160 may be coupled to each other.

In this case, as shown in FIG. 3, when the connection frame 170 is attached to the rear of the tractor 10 and installed, the supporting force of the connection frame 170 may be further improved.

3, the second fixing frame 160 and the connecting frame 170 may be included only when the extension part 140 is formed to block the height of the tractor 10 according to the second embodiment of the present invention. It may be understood that this is included, but is not limited thereto. As shown in FIG. 2, the second fixing frame 160 and the connecting frame 170 may be included even when the extension part 140 is formed to block only a part of the height of the tractor 10.

Meanwhile, according to the present exemplary embodiment, the first fixing frame 150, the second fixing frame 160, and the connecting frame 170 may be hinged to be foldable at each end thereof. According to this, the extension unit 140 of the present embodiment may be folded by the hinge movement and stored in the rear of the tractor 10 after the traveling of the freight vehicle is completed, and may be used by the hinge movement again when necessary.

4 is a view illustrating in detail some components included in the air resistance reduction apparatus 100 for a van according to an embodiment of the present invention. As described above, the air resistance reduction apparatus 100 for a van of the present invention relates to a biomimetic technology designed to mimic the shape of a head of a sea lion. Hereinafter, with reference to Figure 4 will be described in more detail with respect to the specific shape of the air resistance reduction device 100 for a van of the present invention.

4 (a) schematically illustrates one side and a plane of the main body 110, the air flow changer 120, and the air flow controller 130 of the air resistance reduction apparatus 100 for a van according to the present embodiment. Drawing. As described above, the vane air resistance reduction apparatus 100 of the present embodiment includes a streamlined main body 110 to reduce air resistance more effectively. Referring to Figure 4 (a), it can be seen that the main body portion 110 of the present embodiment has a streamlined shape from the front side to the rear side also on the side, and a streamlined shape from the front side to the rear side even on a plane. It can be confirmed that has.

Referring to Figure 4 (a), the length of the body portion 110 is defined as L, the length of the tractor 10 is defined as L _c . Referring together to FIGS. 4A and 4B, the length of the extension 140 is defined as G. FIG. In this case, it can be seen that the length L of the main body 110 according to the present embodiment is equal to the sum of the length Lc of the tractor 10 and the length G of the extension 140.

On the other hand, referring to Figure 4 (c) the height of the trailer 20 is defined as H. In addition, in FIG. 4A, it can be seen that the height of the air resistance reduction apparatus 100 for a van is defined as H ₁ . More specifically, the height H ₁ of the air resistance reduction apparatus 100 for a van means the height from the bottom of the main body 110 to the highest point of the air flow controller 130. On the other hand, referring to Figure 4 (b) and 4 (c), the height of the tractor 10 according to the present embodiment is the tractor 10 from the bottom of the space connecting the tractor 10 and the trailer 20 The upper surface of the, that is to say the height to the roof of the tractor 10, is defined as H ₂ . Therefore, the height H ₂ of the tractor 10 according to the present embodiment does not mean the height from the ground to the roof of the tractor 10.

At this time, according to the present embodiment, the height H of the trailer 20 is equal to the sum of the height H ₁ and the height H ₂ of the tractor 10 from the main body 110 to the highest point of the air flow controller 130. It can be seen.

Meanwhile, as described above, the length of the extension 140 is defined as G, which has been described with reference to FIG. 4B. The length of the space between the tractor 10 and the trailer 20 means the distance between the front of the trailer 20 from the back of the tractor 10 and it can be seen that it is defined as G ₀ with reference to (c) of FIG. 4.

In this case, in order to further reduce the air resistance, the air resistance reduction device 100 for a van according to the present embodiment has a length G ₀ of the space G between the tractor 10 and the trailer 20. It has a ratio of 40% or more and 80% or less. More specifically, the length G ₀ of the space between the tractor 10 and the trailer 20 may be 50% or more and 70% or less of the length G of the extension 140, and as an example, the tractor 10 An embodiment where the length G ₀ of the space between the trailer 20 and the trailer 20 corresponds to 60% of the length G of the extension 140 is shown.

As described above, when the length G ₀ of the space between the tractor 10 and the trailer 20 has a ratio of 40% or more and 80% or less of the length G of the extension 140, the side of the tractor 10 and By controlling the air flow in the space between the tractor 10 and the trailer 20, the air resistance can be reduced.

Referring to FIG. 4A, the front width of the main body 110 coupled with the front of the tractor 10 is defined as W ₀ , and the rear width of the main body 110 extending toward the trailer 20 is W. Referring to FIG. -Defined as ₁ According to the present embodiment, the body portion 110 front width W ₀ is the same as the width of the tractor 10, and the body portion 110 rear width W ₁ is the same as the width of the trailer 20.

On the other hand, Figure 4 (b) is a diagram defining the deflection angle. The deflection angle is defined by the length difference between the main body 110 front width W ₀ and the main body 110 rear width W ₁ , and for accurate measurement of the deflection angle, the main body 110 front width W ₀ and the main body portion ( 110 The center of the rear width W ₁ is measured to match. According to this embodiment, the deflection angle of the air resistance reduction apparatus 100 for a van measured in the above manner may be greater than 0 ° and less than or equal to 10 °. By having such a deflection angle, the air resistance can be further reduced.

5 is a view showing a modification of the air resistance reduction device 100 for a van of the present invention, respectively. More specifically, Figure 5 (a) is a diagram schematically showing the extension portion 140 is formed with a pattern portion 142 at one end, Figure 5 (b) is a vortex generating unit 144 on the surface It is a diagram schematically showing the extension 140 further including.

Referring to FIG. 5A, a pattern portion 142 may be formed at one end of the end portion of the extension portion 140 toward the trailer 20, that is, the exposed portion without connection with another configuration. . The pattern portion 142 may have a shape in which a predetermined shape is repeated or an irregular shape is arranged. For example, in FIG. 5A, an extension part 140 in which a sinusoidal pattern part 142 is formed is illustrated. As such, when the pattern part 142 is formed at the end of the extension part 140, the driving stability of the van may be increased, and the noise generated during the driving may be reduced.

Referring to FIG. 5B, the extension part 140 of the present embodiment is located on the side of the extension part 140 adjacent to the trailer 20 and protrudes outward from the surface of the extension part 140. It further includes a plurality of vortex generating unit 144 is formed. The plurality of vortex generating units 144 according to the present exemplary embodiment may be arranged side by side along the height direction of the extension 140. The vortex generator 144 may generate vortices in a flow of air flowing toward the extension 140 by riding the side of the tractor 10 to further increase driving stability of the freight vehicle.

FIG. 6 is a view schematically illustrating a folding process of the extension 140 having a bellows shape according to a modification of the present invention. Extension unit 140 of the present embodiment can be stored folded to the rear of the tractor 10 when the use of the extension unit 140 is completed, the traveling of the van is completed. FIG. 6A illustrates a step of preparing an extension by applying an external force to the extension 140, and FIG. 6B illustrates a process in which the extension 140 is being folded. As shown in FIG. 6B, the extension 140 of the present embodiment may be folded in a bellows shape in the folding process. 6 (c) is a view schematically showing the extension 140, the folding is completed is stored in the rear of the tractor (10). When the extension part 140 is unnecessary, durability of the extension part 140 can be improved by being folded and stored as shown in FIG. 6C. Therefore, the replacement cycle of the extension 140 may be longer, thereby improving the economics of the air resistance reduction apparatus 100 for a freight vehicle.

FIG. 7 is a view schematically illustrating a folding process of the first fixed frame 150 folded by the hinge according to another modification of the present invention. Referring to FIG. 7, the first fixing frame 150 of the present modified example has a foldable structure in which a plurality of frames are hinged and connected by a hinge h. Referring to (1) of FIG. 7, when an external force acts in the same direction as that indicated by the arrow toward the center to fold the first fixing frame 150, one of the hinges h is shown in the direction indicated by the arrow. Move along. Referring to FIG. 7 (2), the hinge h that forms the vertex may also be moved in the direction of the arrow. 7 (3) shows the first fixed frame 150 is completed folding. When the first fixed frame 150 is folded and stored as shown in FIG. 7, as described above, the durability of the first fixed frame 150 may be improved, and as a result, a replacement cycle may be lengthened, thereby enabling more economical use. Do.

Table 1 summarizes the results of the air resistance analysis of wind tunnel tests on a 40ft tractor trailer model. Comparative Example 1 vehicle is a vehicle that is not attached to the air resistance reduction device for a truck, Comparative Example 2 does not include an air flow change unit and the air flow control, the vehicle air resistance reduction device 100 consisting of a main body portion of a flat shape. The vehicle is attached. Example 1 The vehicle is a vehicle to which the air resistance reduction apparatus 100 for a freight vehicle according to the first embodiment of the present invention shown in FIGS. 1B and 2 is attached. c) and a vehicle to which the air resistance reduction apparatus 100 for a van according to the second embodiment of the present invention shown in FIG. 3 is attached.

Table 1 shows the air resistance coefficient (C _D ) and the air resistance coefficient improvement rate (%) calculated through the wind tunnel experiment for Comparative Examples 1 and 2 and Examples 1 and 2, respectively. The improvement rate of the air resistance coefficient of Table 1 is a relative value that calculates how much the air resistance is reduced in other experimental examples based on Comparative Example 1.

division	Air resistance coefficient (CD)	Air resistance coefficient improvement rate (%)
Comparative Example 1	0.747	standard
Comparative Example 2	0.726	-2.8%
Example 1	0.699	-6.3%
Example 2	0.625	16.2%

As shown in Table 1, in Example 1, the air resistance coefficient was reduced by about 6.3% compared to Comparative Example 1, and the air resistance coefficient was improved by about 125% compared to Comparative Example 2. On the other hand, in the case of Example 2, the improvement rate of the air resistance coefficient was found to decrease by 16.2% compared to Comparative Example 1.

As shown in Table 1, according to the embodiments of the present invention, it can be seen that the air resistance can be significantly reduced compared to Comparative Example 1 without the air resistance reduction device 100 for the van. Therefore, the fuel economy of the van is improved, and as a result, carbon dioxide emissions due to the van of the van can also be reduced, thereby enabling a more environmentally friendly van.

In the above, various embodiments and modifications of the air resistance reduction device 100 for a van were described. According to the present embodiments, by effectively controlling the flow separation occurring in the space between the tractor 10 front part and the tractor 10 and the trailer 20, the space between the tractor 10 and the trailer 20 is formed Recirculation regions and turbulent kinetic energy can be reduced. In addition, the flow rate generated in the space between the side of the tractor 10 and the tractor 10 and the trailer 20 further includes an extension 140, instead of only controlling the air flow passing through the upper surface of the tractor 10. It can be controlled together, resulting in an additional drag reduction effect and an improvement in driving stability.

While specific embodiments of the invention have been described and illustrated above, it is to be understood that the invention is not limited to the described embodiments, and that various modifications and changes can be made without departing from the spirit and scope of the invention. It is self-evident to those who have. Therefore, such modifications or variations are not to be understood individually from the technical spirit or point of view of the present invention, the modified embodiments will belong to the claims of the present invention.

[Description of the code]

10: Tractor

20: trailer

100: air resistance reduction device for trucks

110: main body

120: air flow change unit

130: air flow control

140: extension part

142: pattern portion

144: vortex generator

150: first fixing frame

160: second fixed frame

170: connecting frame

Claims (13)

1. In order to reduce the air resistance of a truck including a tractor and a trailer,

   A body part coupled to the roof of the tractor and including a surface formed of a streamlined curved surface;

   An air flow changing part protruding from the main body part to form a first curved surface and changing a flow of air flowing along the main body part on the roof of the tractor;

   An air flow controller protruding from the main body to form a second curved surface having a curvature different from the curvature of the first curved surface, and connected to the air flow changing unit to control the flow of air; And

   And an extension part extending from the main body part toward the ground to be coupled to the rear of the tractor to block part or all of the space between the tractor and the trailer.
2. The method of claim 1,

   The length of the said main body part is the same as the length of the said tractor and the length of the said extension part, The air resistance reduction apparatus for vans.
3. The method of claim 1,

   Length of the extension is 40% or more and 80% or less of the length between the tractor and the trailer, the vehicle drag reduction apparatus.
4. The method of claim 1,

   The main body front width is the same as the width of the tractor, the main body rear width is the same as the width of the trailer, the drag resistance device for a truck.
5. The method of claim 4, wherein

   And a deflection angle measured to match the center of the main body front width and the main body rear width and being greater than 0 ° and 10 ° or less.
6. The method of claim 1,

   And the height of the trailer is equal to the sum of the height of the tractor and the height from the bottom of the body portion to the highest point of the air flow control.
7. The method of claim 1,

   One end is coupled to the air flow control, and the other end is coupled to the tractor further comprises a first fixed frame for fixing the air drag reduction apparatus for a van to the tractor, the air drag reduction apparatus for a van.
8. The method of claim 7, wherein

   A second fixing frame having one end coupled to the extension portion and the other end coupled to the tractor to fix the extension portion to the tractor; And

   Further comprising a connection frame for connecting and supporting the first fixed frame and the second fixed frame, air resistance reduction apparatus for a truck.
9. The method of claim 1,

   The extension portion has a bellows shape, air resistance reduction device for a truck.
10. The method of claim 1,

    The extension unit is hinged to the rear of the tractor, a vehicle air resistance reduction device.
11. The method of claim 1,

    The extension end portion further comprises a pattern portion, air resistance reduction apparatus for a truck.
12. The method of claim 6,

    An air resistance reduction apparatus for a freight vehicle, wherein the pattern portion has a sine wave shape.
13. The method of claim 1,

    The extension unit further includes a vortex generating unit projecting outward from the surface of the extension unit, air resistance reduction apparatus for a truck.

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