Abstract:
A lead vehicle includes a chassis and front and rear wheel assemblies supportively coupled to the chassis. A trailer coupling interface is mounted to the chassis and is configured to couple to a tow vehicle. The lead vehicle further includes one or more seals cooperatively including first and second side leg sections positioned on the chassis laterally outwardly of the trailer coupling interface and a cross section positioned forwardly of the trailer coupling interface. The one or more seals are configured to form a barrier between the chassis and a portion of the tow vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/821,160, filed May 8, 2013, which is expressly incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Motor vehicles, and in particular trucks, are a critical component of the system for transporting materials, goods and people from place to place. The amount of energy required to move such vehicles depends on many factors. For instance, a substantial amount of energy is expended to overcome the resistance encountered in moving the vehicle through air. The amount of energy expended depends in large part on the aerodynamic drag force exerted on the vehicle by the air. A vehicle moving through air experiences a drag force, which may be divided into two components: frictional drag and pressure drag. Frictional drag comes from friction generated generally through the boundary layer as the vehicle passes through the air. Pressure drag results from the net pressure forces exerted as the air flows around the vehicle. A substantial component of the pressure drag is associated with the formation of a low pressure zone behind the vehicle, as evidenced by the formation of a wake behind the vehicle. 
     The distinction between frictional drag and pressure drag is useful because the two types of drag are due to different flow phenomena. Frictional drag is typically most important for attached flows that is, where the flow boundary layer has not separated from the vehicle surfaces, and is related to the surface area exposed to the flow. Pressure drag dominates for separated flows, and is generally related to the cross-sectional area of the vehicle facing the air flow. When the drag on the vehicle is dominated by pressure drag forces, it will expend far more energy traveling through air than the same vehicle dominated by friction drag forces. It is therefore advantageous in the design of a vehicle to reduce pressure drag forces, thereby increasing the aerodynamic properties and efficiency of the vehicle. 
     A bluff body, such as a conventional truck hood or front section, produces significant pressure drag at typical highway speeds. One reason for the large pressure drag is the presence of a sharp angle located at a leading edge of the truck hood. More specifically, typical truck front sections include a substantially vertical front surface or grille that meets, along an upper edge, a substantially horizontal top surface. The air flow passing over the front section, therefore, must negotiate an abrupt change in direction as the edge where the hood structure transitions from a substantially vertical orientation to a substantially horizontal orientation. This abrupt turn causes the flow to ‘separate’ from the top surface of the hood, forming a highly turbulent region of air located directly above the top surface of the hood, between the leading edge and the windshield. 
     A tractor-trailer combination is another vehicle that experiences excessive aerodynamic drag. Generally described, tractor-trailer combinations typically include a tractor having a so-called fifth wheel by which a box-like semi-trailer may be attached to the tractor by an articulated connection for transportation of the semi-trailer. By providing the articulated connection, a space or gap is formed between the rear wall of the tractor cab and the forward wall of the semi-trailer. It is well known that this gap, or the gap between succeeding trailers of a tractor trailer combination, causes wake regions and, as a result, pressure drag. 
     Pressure drag on tractor-trailer combinations is not limited to the frontal area of the tractor and/or the gap disposed between the tractor and the articulating trailer. It is well known that the rear end of bluff bodies, such as trailers, are known to contribute significantly to aerodynamic drag, as evidenced by the formation of a wake in the trailing region behind the trailer. The generation of the wake, formed by eddies, can be contributed to the shape of the conventional trailer, which is essentially a rectangular box having a flat, rectangular roof and matching floor, along with flat, rectangular side panels. The front and rear surfaces of such trailers are also generally flat rectangular surfaces. As such, current bluff bodies, such as trailers suitable for use with tractors of the Class 8 type, suffer from a low pressure zone at the rear of the trailer such that the airstream suffers from early separation, resulting in a broad eddying wake forming downstream of the separation. The net result is the creation of considerable aerodynamic drag. 
     SUMMARY 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     One exemplary embodiment of a claimed lead vehicle includes a chassis and front and rear wheel assemblies supportively coupled to the chassis. A trailer coupling interface is mounted to the chassis and is configured to couple to a tow vehicle. The lead vehicle further includes one or more seals cooperatively including first and second side leg sections positioned on the chassis laterally outwardly of the trailer coupling interface and a cross section positioned forwardly of the trailer coupling interface. The one or more seals are configured to form a barrier between the chassis and a portion of the tow vehicle. 
     An exemplary embodiment of a claimed vehicle trailer includes a trailer body having a bottom wall and rear wheel assemblies disposed in a supporting relationship with respect to the trailer body. Left and right side fairings are associated with the trailer body and positioned underneath the bottom wall of the trailer body and rearwardly of the rear wheel assemblies. Each of the side fairings includes an outwardly facing deflector surface that extends upwardly as it extends rearwardly. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a side plan view of a vehicle combination, such as an “over the road” tractor-trailer combination, formed in accordance with aspects of the present disclosure; 
         FIG. 2  is a partial top plan view of the rear section of the tractor of  FIG. 1  when the trailer is decoupled; 
         FIG. 3  is a cross-sectional of a sealing device taken along lines  3 - 3  of  FIG. 2 ; 
         FIG. 4A  is a partial bottom plan view of the trailer of  FIG. 1  depicting one example of an underbody “boat tail” fairing system formed in accordance with aspects of the present disclosure; 
         FIG. 4B  is a partial bottom plan view of the trailer of  FIG. 1  depicting the underbody “boat tail” fairing system in a second, longitudinal position; 
         FIGS. 5A and 5B  are front and rear isometric views of one underbody “boat tail” fairing of  FIG. 4A . 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description set forth below in connection with the appended drawings where like numerals reference like elements is intended as a description of various embodiments of the disclosed subject matter and is not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed. 
     The following discussion provides examples of systems and methods for improving the aerodynamic efficiency (e.g., reduce drag) on vehicles. Several embodiments of the present disclosure are directed to systems and methods that utilize one or more fairings, deflectors, fins, seals, plates, etc., on one or more sections of a vehicle, such as a semi-truck, sometimes referred to as a tractor, a semi-trailer, a tractor-trailer combination, etc., for reducing the aerodynamic drag thereon. As will be described in more detail below, one example of a drag reducing device includes a seal located in proximity of the “fifth wheel” interface between the tractor and trailer. As will be further described in more detail below, another example of a drag reducing device is located underneath the trailer along the aft region thereof. 
     Non-limiting examples of vehicles that may benefit from the aerodynamic devices and methods of the present disclosure include but are not limited to light, medium, and heavy duty trucks, recreational and vocational vehicles, buses, etc., just to name a few. Although embodiments of the present disclosure will be described with reference to a Class 8 truck, trailer, and/or combination, and while the system of aerodynamic devices, separate components thereof, may find their primary use on medium and heavy duty trucks and associated trailers, one skilled in the relevant art will appreciate that the disclosed embodiments are illustrative in nature and, therefore, should not be construed as limited to applications with Class 8 trucks. It should therefore be apparent that one or more of the aerodynamic components and drag reducing methods of the present disclosure can have wide application, and may be used in any situation where reducing the drag of any type of a vehicle is desirable. 
     In the following description, numerous specific details are set forth in order to provide a thorough understanding of exemplary embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that many embodiments of the present disclosure may be practiced without some or all of the specific details. In some instances, well-known process steps have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein. 
       FIG. 1  illustrates a lead vehicle  20  in the form of a heavy duty tractor and a trailing vehicle  22  in the form of a semi-trailer or trailer. The tractor  20  is articulatedly connected to a trailer  22  by a trailer coupling interface  26  (hidden in  FIG. 1  but shown in  FIG. 2 ), such as, for example, a so called fifth wheel, to form a tractor-trailer combination. The connection between the tractor  20  and the trailer  22  forms a space or gap  28 . The systems or any combination of components of the systems hereinafter described may be installed on new vehicles, such as the tractor  20 , the trailer  22 , or the combination, or may be retrofitted on existing vehicles, such as the tractor  20 , the trailer  22 , or the combination. 
     As shown in  FIGS. 1 and 2 , the tractor  20  comprises a chassis  28  (see  FIG. 2 ) is supported by wheels  30  of a front wheel assembly and wheels  34  of a rear wheel assembly. The wheels  30  and  34  are connected to the chassis via conventional axles and suspension assemblies (not shown). In the embodiment shown in  FIGS. 1 and 2 , the rear wheel assembly is of the dual-axle type. 
     A front section  40  of the vehicle  20  is supportably mounted on the chassis, as shown in  FIG. 1 . The front section  40  generally includes a vertically oriented front surface or grille  42 , an optional grille crown (not shown) that surrounds the vertical grille  42 , and a hood  46  that generally covers a block-like shaped engine compartment housing an internal combustion engine that propels the tractor. The hood  46  includes a gently upwardly sloping top skin  48  and downwardly depending side skins  50 . In the embodiment shown, the side skins  50  are integrally formed with fenders  54 , which define wheel wells  58  that house the wheels  30 . The fenders  54  in this example may include integrally formed headlamp assemblies and side turn indicators (not shown). 
     The front section  40  further includes a bumper  64  positioned below the somewhat vertical grille  42 . The bumper  64  “wraps around” the front of the tractor  20  from the wheel well  58  of the left fender  54  to the wheel well  58  of the right fender  54 , horizontally across the front of the vehicle  20 . Below the bumper  64 , an air dam  70  may be provided. The air dam extends downwardly to just proximal the ground surface in order to block the flow of air underneath the tractor  20 , thus reducing drag. 
     The top skin  48  of the hood  40  extends rearwardly from an upper leading edge of the grille crown  44  to the windshield  74  of a cab section  78 , which is supportably mounted on the chassis rearwardly of the front section  40 . The cab section  78  generally includes vertically oriented driver and passenger doors  80 , a roof (hidden in  FIG. 1 ), and an optional sleeper section  84  that, together with the windshield  74 , form a compartment that houses driver and passenger seats, a dashboard with various gages, telematics, system controls, etc., and steering wheel for operating the tractor  20 , and sleeping quarters if the optional sleeper section is included. 
     In the embodiment shown, the cab section  78  includes various aerodynamic devices, such as fairings, to improve the aerodynamics of the tractor. Examples of such fairings may include a roof fairing  94 , which provide a smooth transition from the windshield  74  to the rear end of the cab section  78  as defined by a generally vertically oriented rear wall (hidden in  FIGS. 1 and 2 ). In the embodiment shown, the roof fairing  94  generally extends upwardly as the roof fairings extend rearwardly. The tractor  20  may also include extender fairings  98  disposed at the trailing edges of the cab section  78 . The extender fairings  98  extend rearwardly into the gap  28 , as best shown in  FIG. 1 , and aim to reduce or severely limit the amount of air flow into the gap from cross winds, head winds, etc. 
     The tractor  20  may optionally include one or more chassis fairings that aid in covering one or more structural aspects of the tractor, such as the gas tank, storage boxes, etc. The fairings provide improved air flow, and aid in inhibiting air flow underneath the chassis. As a result, drag on the tractor  20  is reduced. In the embodiment shown in  FIG. 1 , the one or more chassis fairings may include a front chassis fairing  110 . The front chassis fairing  110  in some embodiments includes integrated steps for cab ingress/egress. Additional fairings, such as rear or quarter fender fairings, may be provided or integrally formed with the front chassis fairing  110 . The one or more chassis fairings may also include a mid chassis fairing(s)  114 . The mid chassis fairing(s) in some embodiments is hingedly coupled to the chassis for providing access to the gas tanks, compressed air tanks, storage boxes, hoses, etc. The one or more chassis fairings may optionally include a rear chassis fairing  120 . The rear chassis fairing forms fender-like structure that covers the wheels  34  of the rear wheel assemblies and can extends from the mid chassis fairing  114  to the end of or aft of the chassis. As will be described in more detail below, the rear chassis fairings  120  includes a top surface for supporting a sealing device. 
     As briefly discussed above, the interface between the tractor  20  and the trailer  22  creates a gap that left unattended causes large amounts of drag on the combination. As will now be explained in more detail, embodiments of the present disclosure include one or more aerodynamic devices to address this gap problem. For example, a deck plate  124  can be mounted to the chassis rearwardly of the rear wall of the cab section  78 , as shown in  FIG. 2 . The deck plate  124  aims to reduce or severely limit the amount of air that flows into the gap to flow underneath the rear wheel assembly and underneath the trailer  22 . In some embodiments, the deck plate  124  in conjunction with the rear chassis fairings  120  and/or other support structure supports a sealing device  140 . The sealing device  140  in some embodiments extends generally around an opening  146 , which provides access to, for example, the trailer coupling interface  26 , rear wheel assemblies, etc. The sealing device  140  is configured and arranged to provide a seal between the deck plate  124  and the rear chassis fairings  120  and/or other support structure and the bottom surface of the trailer  22  when coupled to the tractor  20 . 
     In some embodiments, the sealing device  140  is in the form of a bulb seal and is disposed in a U-shaped pattern, with the sides of the seal extending between the bottom of the trailer and the top surface of the chassis fairing(s). In that regard, the sealing device  140  includes side sections  150  and  152  and a front section  156 . In some embodiments, the one or more sealing devices  140  includes a material selected rubber, a thermoplastic elastomer, synthetic rubber, etc., and can be formed in one embodiment by rolling a sheet  158  of such material into a shaped having a generally circular cross-section, the ends of which being hermetically sealed, as shown in  FIG. 3 . In other embodiments, the sealing can be formed as a fluid (e.g., gas, liquid, etc.) filled bladder, foam core bladder, etc. In these and other embodiments, the bulb seal has a height greater than about three inches, and is in the range of about five inches and about six inches in some embodiments. 
     As shown in  FIGS. 1 and 4A-4B , the trailer  22  includes a trailer body  160  that defines a cargo carrying interior cavity (not shown). In the embodiment shown, the trailer body  160  is generally rectangular in shape, having a generally planar, vertically oriented front and rear end panels  162  and  164 , generally planar, vertically oriented side panels  166 , a generally planar top panel  168 , and a generally planar bottom panel, sometimes referred to as a cargo-supporting floor deck  170 . 
     The undercarriage of the trailer  22  is comprised of groupings of various drag-producing components, which generally reside below a cargo-supporting floor deck  170 . The drag-producing components of a semi-type cargo trailer undercarriage customarily include rear axles and wheels of the rear wheel assembly  174 , and other components, such as brake components, suspension components, and longitudinal and transverse structural support members not shown for ease of illustration but well known in the art. 
     In accordance with another aspect of the present disclosure, a fairing system provided aft of the trailer wheels can be employed to reduce the drag on the trailer and/or tractor-trailer combination. In that regard, attention is directed to  FIGS. 1 and 4A-4B , which illustrates an underbody “boat tail” fairing system, generally designated  180 . The fairing system  180  includes left and right fairings  182  and  184 , which may include panels, plates, deflectors, etc, that form outwardly facing air deflecting or directing surfaces  188  and  190 , respectively. As shown in  FIG. 4A-4B , the left and right underbody fairings  182  and  184  extend rearwardly from just aft of the rear wheel assembly to the rear panel  164  of the trailer  22 . As the underbody fairings extend rearwardly, the surfaces  188  and  190  slant generally inwardly and optionally upwardly, as shown in  FIGS. 1, 5A-5B . 
     In some embodiments, a notch  194  or other interface can be provided at the rear edge of the underbody fairings  182  and  184  to accommodate, for example, a rear trailer bumper  198 , as shown in  FIG. 4A . In these and other embodiments, the left and right fairings  182  and  184  can be used in combination with a trailer boat tail or similar device to reduce drag caused in part by the wake region aft of the trailer body. 
     In some embodiments, the underbody fairings  182  and  184  are hingedly mounted to the trailer  22  at their front ends about a generally vertical axis. The fairings  182  and  184  are pivotally movable from the first or slanted position shown in  FIG. 5A , which aids in the reduction of drag as the trailer is moving forwardly, to the generally longitudinal position also shown in  FIG. 5B . This second or longitudinal position allows the underbody fairings  182  and  184  to avoid interfering with the rear wheel assembly  174  or bogie on trailer models that employ sliding bogies, sometimes referred to as slide wheels. One example of a sliding bogie is described in U.S. Pat. No. 8,573,680, the disclosure of which is hereby incorporated by reference. 
     In the embodiment shown, the fairings  182  and  184  are passively moved from the first, slanted position and the second, longitudinal position, via rearward movement of the sliding rear wheel assembly  174 . The fairings may be biased in the first, slanted positions, via spring assemblies (e.g., torsions springs, etc.) associated with each left and right fairing. Alternatively or additionally, the left and right fairings may be coupled via a tension spring  200  or the like. Other configuration for moving the fairings between the first and second positions may be employed. For example, the left and right fairings can be moved between the first and second positions via actuators, such as manually or motor operated lead screws, hydraulic/pneumatic cylinders, etc., and associating controls. 
     It should be noted that for purposes of this disclosure, terminology such as “upper,” “lower,” “vertical,” “horizontal,” “fore,” “aft,” “inner,” “outer,” “inwardly,” “outwardly,” “proximal”, “distal,” “front,” “rear,” etc., should be construed as descriptive and not limiting the scope of the claimed subject matter. Further, the use of “including,” “comprising,” or “having,” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. 
     The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure which are intended to be protected are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure, as claimed.