Patent Application
20240083520
The subject matter of the present invention relates to an apparatus that improves aerodynamic performance of the trailer of a tractor trailer. More particularly, the present application involves an apparatus that includes an angled skirt, an aerodynamic mud flap, a rib cover, and a top fairing that are configured for being positioned onto the trailer in order to improve aerodynamic performance.
Trailers towed by trucks and similar apparatuses for transporting cargo can be large, unwieldy, and include geometries which invite inefficiencies during travel. One aspect of these inefficiencies concerns the aerodynamics of the trailer. For maximum capacity, the trailer is box shaped which is not the most aerodynamically available option. In an effort to improve trailer aerodynamics, trailers have been built, supplemented, or retro-fitted with trailer skirts (or side skirts) that are devices affixed to the underside of the trailer which limit air circulating in the empty space between the trailer's axles. By reducing the amount of airflow in this space, drag caused by turbulence is reduced and permits the trailer to be towed more efficiently, increasing the gas mileage and performance of the vehicle and its cargo. Large skirts are known to save more fuel than smaller skirts. However, a larger trailer skirt is both more expensive, more likely to be damaged, more difficult to install, and increases logistics cost. Large skirts can fit on full sized, 53 foot, trailers but cannot fit on smaller sized trailers thus complicating fleet logistics in that different sized skirts have to be installed on different sizes trailers. Also, larger trailer skirts increase the weight of the trailer and limit access under the trailer where items such as refrigerator fuel tanks, spare tires, tire chains, or toolboxes are located.
As large skirts extend the majority of the length present between the trailer tires and the drive tires, the breakover angle of the tractor and trailer combination may cause the large skirt to impact the roadway or other object when travelling upwards over a hill. Larger skirts have more area and thus increased chances of being damaged by side impacts with obstacles. In order to eliminate the negative consequences of having a large trailer skirt under the trailer, systems have been designed to remove the presence of the large trailer skirt yet still maintain some of the aerodynamic performance the large trailer skirt affords. Such aerodynamic systems employ aerodynamic ramps, wedges, or products located at the rear end of the trailer. These aerodynamic components may be located on the sides of the trailer or extend from the back, terminal end of the trailer. Although these systems may increase access under the trailer and eliminate damage that would otherwise occur to the trailer skirt, such systems cannot achieve the fuel savings a large trailer skirt offers. As such, there is room for variation and improvement within the art.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
The use of identical or similar reference numerals in different figures denotes identical or similar features.
Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a third embodiment. It is intended that the present invention include these and other modifications and variations.
The present invention provides for an apparatus 10 that achieves aerodynamic performance of a trailer 12 when hauled by a tractor 94. The apparatus 10 includes an optimized small trailer skirt 14, and a rib cover 74 that covers cross-members 96 of the trailer 12, an aerodynamic mud flap 22, and a top fairing 26. The trailer skirt 14 has an outer surface 16 a majority of which is oriented relative to the longitudinal direction 30 so as to be oriented at an angle 20 to the longitudinal direction 30 that is from 3 degrees to 7 degrees. The trailer skirt 14 extends inboard in the lateral direction 32 upon forward extension in the longitudinal direction 30. The aerodynamic mud flap 22 has a barrier section 24 that has apertures therethrough to block particles from flowing through the barrier section 24 but allow air to flow therethrough. The top fairing 26 is located closer to the rearward terminal end 36 than to the forward terminal end 38 in the longitudinal direction 30. The apparatus 10 with the aforementioned components provides a fast return on investment that minimizes material used per unit of fuel savings. The trailer skirt 14 as configured allows for access under the trailer 12, improves breakover angle, and is less prone to being damaged.
The trailer skirt 14 is positioned generally rearward on the trailer 12. In this regard, the trailer 12 has rearward terminal end 36 and a forward terminal end 38 in the longitudinal direction 30. A trailer length 70 extends from the rearward terminal end 36 to the forward terminal end 38 in the longitudinal direction 30. The longitudinal midpoint 72 of the trailer 12 is located halfway between the terminal ends 36, 38 in the longitudinal direction 30. The trailer skirt 14 has an outer surface length 17 that extends farther in the longitudinal direction 30 than in the lateral direction 32 or the height direction 34. The outer surface length 17 can be measured by extending a measuring device from the rearward to forward ends of the trailer skirt 14. The outer surface length 17 is shown as extending between these points and being angled an angle 20 to the longitudinal direction 30. Additionally or alternatively, since the angle 20 is so small it will be the case that the overall longitudinal length 66 of the trailer skirt 14 will be about the same as the outer surface length 17, and the outer surface length 17 could be assigned or calculated by using simply the overall length in the longitudinal direction 66. Upon obtaining the outer surface length 17, the trailer skirt 14 may be positioned on the trailer 12 so that a majority of the outer surface length 17 is located rearward of the longitudinal midpoint 72 in the longitudinal direction 30. In this regard, a greater portion of the length of the outer surface 16 is rearward of the longitudinal midpoint 72 in the longitudinal direction 30, and a smaller portion of the outer surface length 17 measured in the longitudinal direction 30 is forward of the longitudinal midpoint 72. The area of the outer surface 16 need not be calculated when making this measurement.
The trailer 12 has a bogie assembly 82 that carries a plurality of tires 84. The bogie assembly 82 may be adjustable in the longitudinal direction 30 to account for different loading arrangements of the trailer 12. The trailer skirt 14 can be arranged relative to the bogie assembly 82 so that the entire trailer skirt 14 is located forward of the bogie assembly 82 in the longitudinal direction 30. As such, the entire trailer skirt 14 can be located forward of all of the tires 84 of the bogie assembly 82 in the longitudinal direction 30. The trailer skirt 14 may be forward of the bogie assembly 82 and the tires 84 even upon moving an adjustable bogie assembly 82 completely forward in the longitudinal direction 30. In other embodiments, the trailer skirt 14 may in fact extend rearward of portions of the bogie assembly 82 or tires 84 in the longitudinal direction 30.
The trailer 12 may include landing gear 88 that can be extended onto the ground 98 to support the trailer 12 when the tractor 94 is not attached to and supporting the front end of the trailer 12. When the tractor 94 is attached to and supports the trailer 12, the landing gear 88 may be retracted up off of the ground 98. The trailer skirt 14 can be positioned on the trailer 12 so that the entire trailer skirt 14 is located rearward of the landing gear 88 in the longitudinal direction 30. In yet other arrangements of the apparatus 10, some portion of the trailer skirt 14 may extend to and be forward of the landing gear 88 in the longitudinal direction 30.
In order to achieve improved aerodynamic performance, the trailer skirt 14 is oriented at an angle to the longitudinal direction 30. In this regard, the trailer skirt 14 extends inboard in the lateral direction 32 upon extension of the trailer skirt 14 forward from rear to front in the longitudinal direction 30. The outer surface 16 has an outer surface majority length 18 which is a portion of the outer surface length 17 that extends over a majority of the length of the outer surface length 17. Because the trailer skirt 14 outer surface 16 is flat, the outer surface majority length 18 can be identical to the outer surface length 17. However, if the outer surface length 17 is primarily flat but has a curved front end, the outer surface majority length 18 can be the flat portion of the outer surface 16 and the curved portion of the outer surface 16 is not part of the outer surface majority length 18. The angle 20 is the angle of the outer surface majority length 18 to a line extending only completely in the longitudinal direction 30.
The angle 20 may be 3, 4, 5, 6, or 7 degrees in certain exemplary embodiments. In some embodiments, the angle 20 is from 3 to 7 degrees, from 5 to 6 degrees, or 5.5 degrees in various exemplary embodiments. The optimized, most favorable angle 20 is 5.5 degrees, although others in the 3-7 degree range will work as well. When calling for a range of angles, it is to be understood that the range includes the numbers of the limits in addition to all numbers within the two outer limits. The provision of two trailer skirts 14 oriented at the aforementioned angle 20 provide at subsonic flow a velocity decrease in a divergent nozzle. This causes the flow of air between the trailer skirts 14 to slow down due to the angles 20 before reaching the bogie assembly 82 and tires 84. This slow down of air reduces pressure on the tires 84 and bogie assembly 82 structure and compliments the wake structure which enhances the effectiveness of a present top fairing 26. The angle 20 is present so that the leading edge of the trailer skirt 14 is positioned inboard in the lateral direction 32 far enough to prevent air flow from entering under the trailer 12. This insetting of the leading edge of the trailer skirt 14 can be accomplished by using a long trailer skirt with a small angle as is known, or by using a short trailer skirt 14 with a large angle 20 which is not known. The larger angle 20 allows for the same level of inset of the leading edge of the trailer skirt 14 as would a longer skirt accomplish.
The trailer 12 may be constructed so that a plurality of cross-members 96, sometimes referred to as ribs, are at the lower surface 78 of the trailer 12. The cross-members 96 extend in the lateral direction 32 of the trailer 12 and each one of the cross-members 96 is spaced from successive cross-members 96 in the longitudinal direction 30. Wind may engage the cross-members 96 during travel of the trailer 12 and cause aerodynamic drag or otherwise detract from the aerodynamic properties of the trailer 12. The apparatus 10 includes a rib cover 74 that covers a portion of at least one or more of the cross-members 96 in order to minimize or prevent drag on these portions of the cross-members 96. The rib cover 74 may engage the cross-members 96 or could be spaced therefrom so long as the rib cover 74 minimizes drag associated from wind hitting the cross-members 96. The rib cover 74 may engage the trailer skirt 14 or could be spaced therefrom. The rib cover 74 is positioned so as to be outboard of the trailer skirt 14 in the lateral direction 32. In this regard, the rib cover 74 is outboard in the lateral direction 32 from the outer surface 16 and the outer surface 16 may directly face the rib cover 74. The rib cover 74 may be wedge shaped and can extend along the entire outer surface length 17 such that the rib cover 74 extends the same amount in the longitudinal direction 30 as does the trailer skirt 14. The rib cover 74 may be integrally formed with the trailer skirt 14 or could be a separate component that is attached thereto or spaced therefrom. The rib cover 74 may be positioned so that the majority of the longitudinal length of the rib cover 74 is rearward of the longitudinal midpoint 72. Further, the rib cover 74 can be set up so that all of the rib cover 74 is rearward of the 80% point 80 in the longitudinal direction 30. Additionally, or alternatively, the entire rib cover 74 can be oriented so that the entire rib cover 74 is completely forward of the bogie assembly 82 in the longitudinal direction 30. Still further, the entire rib cover 74 may be completely rearward of the landing gear 88 in the longitudinal direction 30. The rib cover 74 can be limited to being outboard of the trailer skirts 14 in the lateral direction 32, but there are no rib covers 74 covering any of the cross-members 96 at locations inboard from the two trailer skirts 14 in the lateral direction 32. As such, embodiments exist in which the rib covers 74 are present and are all located only outboard of their respective trailer skirts 14 in the lateral direction 32.
Although described and labeled in the figures as a single trailer skirt 14 and a single rib cover 74, it is to be understood that a second trailer skirt 14 and a second rib cover 74 can be located on the opposite side of the trailer 12 in the lateral direction 32 as shown in
As described, the outer surface 16 can be flat so that the outer surface majority length 18 is the same as the outer surface length 17.
The trailer skirt 14 is attached to the trailer 12 via one or more brackets 92 which can be attached to the lower surface 78 of the trailer 12 and extend downward therefrom in the height direction 34. Although two brackets 92 are shown, any number may be used to support the trailer skirt 14 in accordance with other exemplary embodiments. The brackets 92 can be rigid brackets or may be able to flex to some degree so that if the trailer skirt 14 is impacted the brackets 92 and trailer skirt 14 can flex to absorb this impact. In some embodiments, the brackets 92 could instead be bi-modulus bending members that support the trailer skirt 14 upon impact in the lateral direction 30 and function to push the deflected trailer skirt 14 back into its normal, aerodynamically beneficial position. If bi-modulus bending members are used, supporting brackets to hold the trailer skirt 14 onto the trailer 12 can be provided as well. The brackets 92 are on the side of the trailer skirt 14 opposite to the outer surface 16.
The apparatus 10 achieves optimized aerodynamic performance for longer trailers 12 as compared to shorter trailers 12, and thus the apparatus 10 is provided for use on these longer trailers 12. The difference between a longer trailer 12 and shorter trailer 12 can be found in measurement of the trailer length 70. The apparatus 10 is provided for use on trailers 12 having a trailer length 70 that is 35 feet or greater. In some embodiments, the trailer length 70 is 48 feet or greater. In other embodiments, the trailer 12 is a full sized trailer 12 which has a trailer length 70 of 53 feet. The trailer length 70 is thus of a larger, as opposed to a smaller, sized trailer 12. In some embodiments, the trailer skirt 14 can have an overall length 66 in the longitudinal direction 30 that is 25% or less than the trailer length 70. In other embodiments, the overall length 66 is 20% or less than the trailer length 70.
A sideview partially in cross-section of the top fairing 26 is shown in
A tailing airflow surface 44 of the top surface of the top fairing 26 extends from the leading airflow surface 40 and terminates at a tailing airflow surface terminal end 52 that is at the same position in the longitudinal direction 30 as the rearward terminal end 36. The tailing airflow surface 44 is convex in shape and has a radius of curvature 50 that may in some instances have a center point that is lower than the lower surface 78 in the height direction 34. The tailing airflow surface 44 may be made of multiple radii of curvatures or flat sections in other embodiments. In the embodiment disclosed in
The angle 42 may be from 5 degrees to 14 degrees, from 6 to 13 degrees, from 7 to 12 degrees, from 8 to 11 degrees, from 9 to 10 degrees, from 5 to 10 degrees, from 6 to 9 degrees, from 9 to 14 degrees, from 10 to 13 degrees, or from 11 to 14 degrees in accordance with various exemplary embodiments. The arms of the angle 42 extend rearward in the longitudinal direction 30 from the vertex of the angle 42. The meeting location 46 is located at a position on the outer surface of the top fairing 26 in which the leading airflow surface 40 and the tailing airflow surface 44 share a common tangent line. Although specifically shaped and configured leading and tailing airflow surfaces 40 and 44 are shown, it is to be understood that these elements 40 and 44 along with any other portion of the upper surface or part of the top fairing 26 can be variously configured in accordance with other exemplary embodiments. A frame 48 of the top fairing 26 engages the top surface 28 and functions to hold the airflow surfaces 40, 44 onto the top surface 28. The frame 48 can be located within or over a gutter of the top surface 28 and can be made of one or multiple parts.
Once exemplary embodiment of the aerodynamic mud flap 22 that can be employed in the apparatus 10 is shown with reference to
The aerodynamic mud flap 22 has a barrier section 24 that features horizontal louvers 54 spaced from one another in the height direction 34 so as to form apertures 90 between successive horizontal louvers 54 in the height direction 34. One embodiment of the aerodynamic mud flap 22 is shown in
The horizontal louvers 54 have upper and lower horizontal louver surfaces 58, 60 that are angled relative to the longitudinal direction 30 and are arranged in such a way that debris exiting the tires 84 primarily engage the horizontal louvers 54 instead of flowing through the apertures 90 and harassing trailing vehicles. The upper horizontal louver surface 58 is oriented at an angle 62 to the longitudinal direction 30, and the angle 62 may be from 30 degrees to 50 degrees, from 35 to 45 degrees, 40 degrees, or 45 degrees in accordance with various embodiments. The lower horizontal louver surface 60 is oriented at an angle 64 to the longitudinal direction 30, and angle 64 may be from 30 degrees to 50 degrees, from 35 degrees to 45 degrees, 40 degrees, or 45 degrees in various embodiments. The angles 62 and 64 may be the same as one another, or the two angles 62 and 64 can be different in different versions of the aerodynamic mud flap 22.
The increasing aperture 90 size in the height direction 34, and the non-zero degree angles 62, 64 of the horizontal louvers 54 are optimized for increasing air flow through the aerodynamic mud flap 22 while at the same time minimizing the flow of debris through the aerodynamic mud flap 22. The barrier section 24 that includes the apertures 90 can extend along the entire height of the aerodynamic mud flap 22 in the height direction 34. Alternatively, there can be other sections above or below the barrier section 24 in the height direction 34. In the embodiment shown in
The apparatus 10 provides a fast return on investment as the apparatus 10 minimizes material used per unit of fuel savings. The optimized trailer skirt 14 provides performance slightly better than an average trailer skirt but with reduced material. The short trailer skirt 14 provides better ground clearance, better weight per unit fuel saved, reduced number of parts, and compatibility of parts with other trailer configurations. The smaller angled trailer skirt 14 with the rib cover 74 achieves aerodynamic savings similar to a larger trailer skirt. The small size of the trailer skirt 14 along with the low height 68 to length 66 ratio allows for access under the trailer 12 while still providing fuel savings not available through other solutions. When large trailers 12, those having a trailer length 70 over 35 feet, are fitted with aerodynamic solutions, a large trailer skirt is utilized. A large trailer skirt measures 264 inches by 33.25 inches, and when compared to a present small trailer skirt 14 having an overall length 66 of 132 inches and a height 68 of 27 inches (4.9 length/height ratio) the larger trailer skirt is 247% larger in area. The smaller trailer skirt 14 has an angle 20 that measures 5.5 degrees, and rib covers 74 were utilized. The smaller trailer skirt 14 was located completely forward of the bogie assembly 82 and tire 84, and the majority of the outer surface length 18 was rearward of the longitudinal midpoint 72. However, the utilization of the smaller trailer skirt 14 surprisingly saved more fuel. The apparatus 10 with the smaller trailer skirt 14, rib cover 74, top fairing 26, and aerodynamic mud flaps 22 saved 6.7% more fuel than just an aerodynamic system fitted with only the aforementioned large trailer skirt. The aforementioned apparatus 10 with the small trailer skirts 14, rib covers 74, aerodynamic mud flaps 22 and top fairing 26 was also compared to an aerodynamic system that features a large trailer skirt, side and top rear fairings, aerodynamic mud flaps, and a wake reducer. The aforementioned apparatus 10 resulted in 65% of the fuel savings that are achieved with the aerodynamic system that features the large trailer skirt, side and top rear fairings, aerodynamic mud flaps, and wake reducer. However, the aerodynamic system 10 with the small trailer skirts 14, rib covers 74, aerodynamic mud flaps 22 and top fairing 26 achieved 65% of the fuel savings with 35% less material and weight of the system that included the long trailer skirts, side and top rear fairings, aerodynamic mud flaps and wake reducer. The present apparatus 10 is used on trailers 12 having long trailer lengths 70 and not on those trailers 12 having trailer lengths 70 less than 35 feet.
In order to save additional fuel, the size of the trailer skirt 14 can be increased. The optimum efficiency of the length/height ratio should be respected and should not be greater than 6 and should be ideally 5. As such, for every inch of added height 68, 5 to 6 inches of overall length 66 should be added. For a 30 inch tall trailer skirt 14, the overall length 66 should be from 150 to 180 inches. Height 68 may be added until the length 66 is between 30 inches and 32 inches. As this process is conducted, the amount of fuel saved per area of the trailer skirt 14 is reduced, but the overall fuel savings is increased.
In accordance with one experiment conducted, the trailer 12 with the apparatus 10 having the small skirt 14 at the aforementioned positioning, length 66/height 68 ratio, and angle 20, along with the rib covers 74, aerodynamic mud flaps 22, and top fairing 26 was evaluated and resulted in a 7.27 gallon/1000 miles savings versus a trailer 12 without said apparatus 10. This apparatus 10 was compared to a trailer 12 equipped with a large trailer skirt only that measured 264 inches by 33.25 inches which resulted in a fuel savings of 6.81 gallon/1000 miles. No other aerodynamic element on the trailer 12 such as side fairings, wake disruptor 86, or the like are present other than those mentioned.
While the present subject matter has been described in detail with respect to specific embodiments and methods thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be apparent.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/016029 | 2/1/2021 | WO |
