Patent Description:
The present invention relates generally to drag reduction, and more particularly to devices that disrupt the trailing vortex created by the flow of air around a vehicle while traveling.

The pressure drag vortex formed in the wake of vehicles and particularly the type having non-tapered rear ends, such as tractor-trailers, is known to significantly reduce vehicle efficiency while increasing transportation costs. As air flows from the trailing edge of a non-tapered vehicle or trailer, the air converges into a swirling vortex which produces inherent low pressure drag. This low pressure drag formed at the rear of a trailer, combined with high pressure applied to the front of
the vehicle, causes a net pressure differential that generates a force in the opposite direction of travel. The front-to-back pressure differential is the primary source of drag for most large vehicles.

Various attempts have been made to reduce vehicle drag. Such attempts include a host of aerodynamic structures and add-on devices intended to reduce the negative effects created by the low-pressure region formed at the rear of vehicles. For example, <CIT>, issued to Stephens, discloses the use of surface mounted apparatus to interact with boundary layer flow. <CIT>, issued to Ridder, discloses the use of vortex generators to alter flow over the roof surface of a vehicle. <CIT>, issued to Elliott, discloses an array of vortex generators in combination with a bag attachment affixed to the rear of a cargo trailer by straps. <CIT>, discloses attachment of aerodynamic units to the roof of a road vehicle. The published application to Guigne (<CIT>) discloses a drag reducing device for use with transport vehicles.

<CIT> discloses a vortex generator that, in one embodiment, includes an apex having a first width; a rear face having a second width being greater than the first width; a first and second sidewall each extending from the first width of the apex to the second width of the rear face.

<CIT> discloses a body adapted to move downstream through a fluid that has a downstream extending smooth surface terminating at a blunt base.

The attempts revealed in the background art generally rely on vortex generators intended to function within the confines of boundary layer flow. Such devices differ from vortex disruption devices which are intended to function beyond the surface boundary layer and further to prevent or inhibit the formation of a trailing end vortex behind a moving vehicle. Further, the apparatus disclosed in the background art are burdened by a number of limitations and disadvantages that have prevented widespread acceptance and use. Accordingly, there exists a need for advancements in the transportation field directed to increasing fuel efficiency by disrupting the formation of vortex flow at the rear of large vehicles.

It is, therefore, an object underlying the present invention to provide a vortex disruption system for vehicles that is able to reduce transportation costs by increasing vehicle fuel efficiency via drag minimization.

The solution of this object is achieved by the features of claim <NUM>.

The dependent claims contain advantageous embodiments of the present invention.

The present invention overcomes the limitations and disadvantages present in the art by providing a system designed to disrupt the trailing edge vortex created by the flow of air around a vehicle as it travels down the highway. Vortex disruption apparatus are permanently or removably installed or attached or incorporated into the design of cargo and passenger vans, busses, box-trucks, tractor-trailer combinations, or any other vehicle. Trailing edge vortex disruption is achieved by use of a plurality of vortex disruption devices positioned in proximity to the trailing end of a vehicle or trailer. The vortex disruption devices are disposed in adjacently spaced relation and extend away from the vehicle or trailer surface well beyond the fluid dynamic laminar boundary layer formed as the vehicle passes through the air. The boundary layer is that fluid layer which has its velocity affected by the boundary shear. Once installed the vortex disruption devices disperse the air flowing over the disrupter while allowing air to flow normally through the spaces between the devices. The vortex disruption devices thereby inhibit the natural convergence of airflow and prevent the formation of a low-pressure vortex beyond the trailing edge of the vehicle.

In a first embodiment, a plurality of fixed vortex disruption devices are secured in spaced relation with the trailing edge of the trailer and secured using a strap. Each fixed vortex disruption device comprises a generally triangular structure having a leading end and a trailing end. Left-hand and right-hand planar surfaces are disposed in diverging and inwardly slanted relation wherein they join along a common upper edge which increases in height from the leading end to the trailing end. When used with the trailer of a tractor-trailer rig, the vortex disruption devices are preferably <NUM> inches long, and when measured at the trailing end, <NUM> inches wide and <NUM> inches tall. In a second embodiment, mechanically actuated vortex disruption devices are provided which are configurable between a generally flat stowed configuration and a functional, outwardly projecting deployed configuration.

So, the vortex disruption system according to the present invention is intended to function beyond the surface boundary layer and to prevent or inhibit the formation of a trailing end vortex behind a moving vehicle. This is one of the most important differences between the vortex disruption system according to the present invention and known vortex generators.

Advantageously, the present invention provides a system (apparatus) that reduces vortex drag at the rear of a vehicle.

Another advantage of the present invention is to provide vortex disruption apparatus for minimizing vehicle drag.

Yet another advantage of the present invention is to provide such vortex disruption apparatus that is easy to install and uninstall.

Still another advantage of the present invention is to provide a vortex disruption system for vehicles that is mechanically deployed for use at desired speeds.

These and other objects are met by the present invention which will become more apparent from the accompanying drawing and the following detailed description of the drawings and preferred embodiments.

The present invention may be understood more readily by reference to the following detailed description taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this invention is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed invention. Any and all patents and other publications identified in this specification are incorporated by reference as though fully set forth herein.

Also, as used in the specification including the appended claims, the singular forms "a," "an," and "the" include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and/or to "about" or "approximately" another particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment.

Turning now to the drawings, <FIG>, apparatus designed to disrupt the trailing edge vortex created by the flow of air around a vehicle as it travels at highway speed in accordance with the present invention are disclosed. In accordance with the present invention, vortex disruption apparatus are permanently or removably installed or attached to cargo and passenger vans, busses, box-trucks, tractor-trailer combinations, or any other vehicle. As best seen in <FIG>, trailing edge vortex disruption is achieved by use of a plurality of vortex disruption devices <NUM> positioned in proximity to the trailing edge or end <NUM> of a vehicle or trailer, referenced as <NUM>. Vortex disruption devices <NUM> are disposed in adjacently spaced relation and extend away from the vehicle or trailer surface well beyond the boundary layer. Once installed the vortex disruption devices <NUM> disperse the air flowing over and around each device while allowing air to flow normally through the spaces between the devices as illustrated in <FIG>. The vortex disruption devices thereby inhibit the otherwise natural convergence of airflow and prevent to formation of a low-pressure vortex beyond the trailing edge of the vehicle as seen in <FIG> (vortex created behind trailer without vortex disruption devices) and <FIG> (significantly reduced vortex created behind trailer adapted with vortex disruption devices).

In a first embodiment, shown in <FIG>, a plurality of fixed vortex disruption devices <NUM> are secured in spaced relation with the trailing edge <NUM> of trailer <NUM>. The vortex devices are secured to the trailer using a strap <NUM>. Strap <NUM> preferably comprises a flat elongated strap body having connectable ends, preferably adapted with a ratchet mechanism (not shown) to allow for sufficient tightening as is known in the art of ratchet straps. Each fixed vortex disruption device <NUM> comprises a generally triangular structure having a leading end, generally referenced as <NUM>, and a trailing end, generally referenced as <NUM>. Left-hand and right-hand planar surfaces, each referenced as <NUM>, originate at the extreme leading end <NUM>, and are disposed in diverging and inwardly slanted relation wherein they join along a common upper edge <NUM>. Common upper edge <NUM> originates at the extreme leading end <NUM> and increases in height as it extends longitudinally rearward from leading end <NUM> to an open trailing end <NUM>. In a preferred embodiment the trailing end <NUM> terminates within a plane that is perpendicular to the vehicle surface upon which the device is mounted. Each vortex device further includes a bottom <NUM> which defines a generally acute triangular perimeter shaped in the form of an isosceles triangle wherein the smallest angle is formed at the leading end. Bottom <NUM> further defines a strap receiving recess <NUM> extending transversely across the bottom, and a pair of slotted apertures <NUM> for receiving strap <NUM> threadedly disposed therethrough. A plurality of vortex disruption devices <NUM> may thus be affixed to a vehicle using a fastening apparatus, such as a single strap <NUM> as illustrated in <FIG>. While a strap is disclosed in a first embodiment fastening apparatus for removably securing the vortex devices to the vehicle, alternate fastening apparatus and methods of removable or permanent fixation, including the use of adhesive, magnetic attachment, and/or mechanical fasteners, are considered within the scope of the present invention. The vortex devices are preferably fabricated from foam, fabric, composite material, plastic material, an inflated structure, metal, or any suitable material or structure within the scope of the invention. In addition, the vortex disruption devices may include illumination or lighting systems, such as LED lighting for safety and or area illumination.

As further illustrated in <FIG>, when used with the trailer of a tractor-trailer rig, the vortex disruption devices <NUM> are preferably <NUM> inches long, and when measured at the trailing end, <NUM> inches wide and <NUM> inches tall. It is important that the vortex disruption devices are sized with a height that is sufficient so as to extend well beyond the boundary layer. When used in a tractor-trailer application, it has been found that <NUM> inches is sufficient. It should be noted, however, that variations in the disclosed dimensions for the same or other applications remain within the contemplated scope of the present invention. In addition, the vortex disruption devices are installed with the trailing ends thereof spaced from the trailing edge <NUM> of trailer <NUM>. When used in a tractor-trailer application, it has been found that a <NUM> inch spacing between the trailing end of the vortex disruptor and the trailing end of the trailer is sufficient. It should be noted, however, that variations in the disclosed dimensions for the same or other applications remain within the contemplated scope of the present invention.

<FIG> illustrate a mechanically actuated vortex disruption device, generally referenced as <NUM>, in accordance with an alternate embodiment of the present invention. <FIG> depicts the mechanically actuated vortex disruption device <NUM> in a partially deployed configuration, and <FIG> depicts the device in a fully deployed configuration. As should be apparent, vortex disruption device <NUM> may also assume a retracted or non-deployed configuration wherein the device is substantially flat as seen in <FIG>. Actuation of mechanically actuated device <NUM> may be manual, electric, hydraulic, mechanical, pneumatic, or any other suitable actuation structure or system.

Each mechanically actuated vortex disruption device <NUM> includes a base frame <NUM> and a pair of left-hand and right-hand diffractor plates, each referenced as <NUM>. Diffractor plates <NUM> are connected along adjacent edges thereof by a hinge connection, <NUM> which allows for pivotal movement along the central upper edge of plates <NUM>. Further, each diffractor plate has a trailing end <NUM> with a lower portion thereof, referenced <NUM>, adapted for slidable mating engagement with a corresponding trailing end 52A of base frame <NUM>. Base frame <NUM> further includes opposing side edges defining an upwardly projecting and inwardly curved lip 52B which functions to receive corresponding outer edge portions of diffractor plates <NUM> when device <NUM> is configured in the non-deployed configuration.

As illustrated in <FIG>, each mechanically actuated vortex disruption device <NUM> is actuated via an actuation system, generally referenced as <NUM>, including a control module <NUM>. Control module <NUM> may receive an input signal from any suitable source including user switch activation, vehicle speed etc. and convert any such input into an output command for deployment and retraction of vortex disruption device <NUM>. In one embodiment, the actuation system includes a linear actuator <NUM> having an actuating member 64A coupled to an anchor structure <NUM>, and an actuating tube 64B having an end thereof adapted with a dowel <NUM> in sliding engagement with a track <NUM>. Dowel <NUM> is further connected to a rigid member <NUM> having a terminal end thereof 70A received within a second track <NUM> connected to hinge <NUM>. A rod <NUM> has a first end 74A pivotally connected to anchor structure <NUM>, and a second end 74B pivotally connected to rigid member <NUM> as shown in <FIG>. An actuation signal from control module <NUM> activates linear actuator <NUM> whereby extension of actuating member 64A causes the actuating tube 64B to slide rearward such that dowel <NUM> slides rearward within track <NUM>. This movement moves rigid member <NUM> to a generally vertical position whereby the terminal end 70A of rigid member <NUM> slides within track <NUM> thereby resulting in raised deployment of vortex disruption device <NUM>. As noted above, linear actuator <NUM> may be electric, hydraulic, or any other suitable actuating mechanism. Further, other actuating mechanisms and linkages may be substituted for those disclosed to deploy and retract vortex disrupter devices <NUM>.

Claim 1:
A vortex disruption system for vehicles (<NUM>) having opposing sides and a roof, and terminating at a rear end (<NUM>), said system being characterized by:
a plurality of vortex disruption devices (<NUM>) adapted to be mounted to said vehicle (<NUM>), and in spaced relation with the vehicle rear end (<NUM>);
each vortex disruption device (<NUM>) including a leading end (<NUM>), a trailing end (<NUM>), and a bottom (<NUM>);
wherein at least said trailing end (<NUM>) or a portion of each of said plurality of vortex disruption devices (<NUM>) extends beyond the fluid dynamic boundary layer formed as the vehicle (<NUM>) moves through the air;
a left-hand planar surface (<NUM>) and a right-hand planar surface (<NUM>), said planar surfaces (<NUM>) originating at said leading end (<NUM>), and extending therefrom in diverging and inwardly slanted relation wherein said planar surfaces (<NUM>) join along a common upper edge (<NUM>).