Patent Publication Number: US-2016236728-A1

Title: Dynamically adjustable airfoil system for road vehicles

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/116,292, filed Feb. 13, 2015. 
    
    
     1. FIELD OF THE INVENTION 
     The present invention relates to motor vehicle performance enhancement systems, and particularly to a dynamically adjustable airfoil system for road vehicles that adjusts the aerodynamic profile of the road vehicle to selectively increase downforce on the vehicle in response to maneuvering conditions. 
     2. DESCRIPTION OF THE RELATED ART 
     High performance road vehicles have external body shapes that serve two general objectives. The first objective is to minimize running resistance by minimizing aerodynamic drag. The second objective is to maximize downforce by maximizing the downward vertical aerodynamic load component, especially at the wheels to insure that they remain on the surface as much as possible. 
     In order to increase the downforce, aerodynamic projecting elements are typically mounted onto the body of the motor vehicle. Among the most common aerodynamic projecting elements are rear spoilers, rear airfoils, and flaps that are arranged at the rear portion of the vehicle and serve the function of increasing the downforce, i.e., the downward vertical aerodynamic load. More complicated versions of these elements have the ability to be automatically adjusted to optimize and maximize the vehicle&#39;s performance. Most of these projecting elements apply downforce on the vehicle external body or on the vehicle&#39;s frame, which is then transmitted to the rear wheels through the suspension system. Such indirect transmission of downforce compromises the performance of the suspension system at high speeds, which reduces the vehicle maneuverability, cornering speed, and ride quality. 
     Therefore, it would be desirable to provide a system that transmits most of the downforce directly to the rear wheels with the ability of automatically adjusting its aerodynamic profile to maximize or minimize the vertical load on each wheel. Such a system would counterbalance the tendencies of a vehicle lift force, i.e., the upward vertical aerodynamic force, resulting from the vehicle&#39;s shape, which reduces the rear weight of the vehicle&#39;s body at high speed. This tendency reduces the overall weight of the vehicle, yet by implementing the system, the rear wheels would experience most of the downforce without compromising the performance of the suspension system. This system would make the road vehicle more agile and nimble at high speeds, in addition to improving rear braking performance, overall ride quality, and a possible reduction in fuel consumption. 
     Thus, a dynamically adjustable airfoil system for road vehicles solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The dynamically adjustable airfoil system for road vehicles includes a pair of airfoils having their respective inner ends pivotally mounted to a central, vertical base on the rear of a road vehicle. An airfoil lift assembly is coupled to an outer end of each airfoil and to a rear wheel suspension system to facilitate dynamic adjustable positioning of the airfoils in response to movements of the suspension system. A split flap is pivotally mounted to each airfoil. A split flap actuator assembly is mounted inside each airfoil and is coupled to a corresponding split flap to selectively and independently open or close the respective split flap. Opening of the split flap to various angles increases downforce exerted on the rear suspension system for improved performance. A controller controls deployment and angular disposition of the split flaps, depending on driving conditions. 
     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an environmental, perspective view of a dynamically adjustable airfoil system for road vehicles according to the present invention. 
         FIG. 2  is an environmental top view of the dynamically adjustable airfoil system of  FIG. 1 . 
         FIG. 3  is a rear view in section of the dynamically adjustable airfoil system of  FIG. 1 . 
         FIG. 4A  is a detailed partial rear view in section of the dynamically adjustable airfoil system of  FIG. 3 , showing the left side of the system. 
         FIG. 4B  is a diagrammatic side view of a linear actuator assembly for the left airfoil in a dynamically adjustable airfoil system for road vehicles according to the present invention. 
         FIG. 5  is a partial rear view in section of a latching assembly for a dynamically adjustable airfoil system for road vehicles according to the present invention. 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The dynamically adjustable airfoil system for road vehicles, generally referred to by the reference number  10  in the drawings, provides adjustable downforce to the rear suspension system RS of a road vehicle C to facilitate increased adherence to a road surface during movement and braking, and to improve overall performance and handling. The dynamically adjustable airfoil system  10  includes a pair of left and right airfoils or spoilers  11   a ,  11   b  pivotally mounted with respect to each other, and an airfoil lift assembly  20  coupled at one end to a conventional high-mounted, double wishbone suspension system RS mounted to the rear wheels RW of a road vehicle at one end and to the respective airfoil  11   a ,  11   b  at the opposite end. An example of the double wishbone suspension system RS can be found in U.S. Pat. No. 7,234,712, issued Jun. 26, 2007 to Yamazaki et al., which is hereby incorporated by reference in its entirety. The coupling of the airfoil lift assembly  20  permits the respective airfoil  11   a ,  11   b  to be independently raised or lowered in response to the generally vertical movements of the rear suspension system. 
     As best seen in  FIGS. 1, 2, and 4B , each airfoil  11   a ,  11   b  is preferably an elongate, generally flat wing configured to provide downforce from the air flowing over the airfoil  11   a ,  11   b  during movement of the vehicle C. A vertical base  13  extends from a center of a rear hatch of the vehicle C, and an inner end of each airfoil  11   a ,  11   b  is pivotally connected to the vertical base  13  at  13   a  and  13   b , respectively. This pivotal connection  13   a ,  13   b  permits each airfoil  11   a ,  11   b  to pivot independently of the other in response to the movements of the rear suspension system. 
     The airfoil lift assembly  20  provides a direct connection between the airfoils  11   a ,  11   b  to the corresponding rear wheel RW and provides for pivoting movements of the airfoils  11   a ,  11   b . Each airfoil  11   a ,  11   b  is coupled to a respective airfoil lift assembly  20  near the outer end of the respective airfoil  11   a ,  11   b . The following description is directed toward the left airfoil lift assembly  20  for clarity and brevity. However, it is to be understood that the right airfoil lift assembly  20  is similarly configured unless indicated otherwise. 
     As best seen in  FIGS. 3, 4A, and 5 , the airfoil lift assembly  20  includes a slanted base  21  at one end of an upper arm UA of the rear suspension system RS. The slanted base  21  is provided with a generally beveled upper surface  21   a  in order to angle the connected components inward towards the vertical base  13 . A damper  22  extends upward from the base  21 , and an elongate airfoil lift tie rod  24  is pivotally connected to the damper  22  at a lower end of the airfoil lift tie rod  24 . The upper end of the airfoil lift tie rod  24  is pivotally connected to a corresponding airfoil  11   a ,  11   b.    
     The damper  22  is provided with a spring  23 , and these two components serve to absorb shocks from the rear wheel RW and protect the respective airfoils  11   a ,  11   b  from potential damage as a result thereof. The damper  22  is preferably a hydraulic damper, although a pneumatic damper or the like can also be used. 
     Each airfoil lift tie rod  24  is configured to extend through a generally elongate rectangular opening or slot  27  in the body of the vehicle C. The slot  27  extends into the wheel housing and confines the movements of the airfoil lift tie rod  24 . Each airfoil lift tie rod  24  includes a lower rubber bushing joint  25   a  and an upper rubber bushing joint  25   b . The rubber bushing joints  25   a ,  25   b  protect the airfoils  11   a ,  11   b  from vibrations and accommodate lateral movements of the wheels RW during vehicular movement. 
     A pair of rotatable rubber stabilizers  26  is mounted inside the slot  27 , and the airfoil lift tie rod  24  extends through the rubber stabilizers  26 . The rubber stabilizers  26  enclose a corresponding airfoil lift tie rod  24 , and they are preferably lubricated to permit rotation of the rubber stabilizers  26  with minimal interference. The enclosed nature of the airfoil lift tie rods  24  assists in constraining the movement of the tie rods  24  vertically and laterally within the slot  27 . Moreover, the stabilizers  26  provide support to the outer ends of the respective airfoils  11   a ,  11   b  and buttress the airfoils  11   a ,  11   b  against the aerodynamic forces acting thereon. 
     Each airfoil  11   a ,  11   b  also includes a respective split flap  12   a ,  12   b  near the outer end of the airfoils  11   a ,  11   b  that can be selectively deployed, depending on the driving conditions. Each split flap  12   a ,  12   b  is a generally flat, rectangular wing section pivotally mounted on the corresponding airfoil  11   a ,  11   b  by one or more hinges  14 . The split flaps  12   a ,  12   b  are deployable or pivotal between a normally closed position and an open position. The closed position is when the split flap  12   a ,  12   b  is substantially flush with the top surface of the airfoil  11   a ,  11   b , providing the least wind resistant aerodynamic profile. The open position is when the split flap  12   a ,  12   b  is pivoted upward with respect to the corresponding airfoil  11   a ,  11   b , thereby providing increased surface area and increased aerodynamic wind resistance. The extent of wind resistance increases as the split flap  12   a ,  12   b  pivots open towards the vertical at increasing angles. Wind resistance creates drag, and the downforce or vertical component is transmitted to the airfoil lift tie rod  24  and to the corresponding rear wheel RW to force the rear wheel RW towards the ground. 
     The split flaps  12   a ,  12   b  are generally smaller in dimension compared to the airfoils  11   a ,  11   b . The split flaps  12   a ,  12   b  are preferably constructed to be substantially flush with the top surface of the airfoil  11   a ,  11   b . It is contemplated, however, that the split flaps  12   a ,  12   b  can also be constructed to extend above or below the top surface of the airfoils  11   a ,  11   b . The corresponding results in drag will not significantly impact the overall performance of least drag and most drag between the closed and open positions of the split flaps  12   a ,  12   b , respectively. 
     To selectively raise or lower the split flaps  12   a ,  12   b , the dynamically adjustable airfoil system  10  includes a split flap actuator assembly  30  for each split flap  12   a ,  12   b . As best seen in  FIGS. 2, 3, 4A, and 4B , the split flap actuator assembly  30  includes a linear actuator assembly  30   a  (shown in  FIG. 4B ) mounted inside each respective airfoil  11   a ,  11   b  near the inner end and coupled to an elongate, rotary push rod  37  extending along the length of the airfoil  11   a ,  11   b . A pair of spaced, split flap tie rods  40  is pivotally mounted to the push rod  37  at one end and pivotally mounted to the corresponding split flap  12   a ,  12   b  at the opposite end. The linear actuator assembly  30   a  selectively pushes and pulls the rotary push rod  37 , causing the connected split flap  12   a ,  12   b  to rise and lower in response. 
     The linear actuator assembly  30   a  includes a relatively slim profile drive motor  31  and a drive gear  32  extending from the drive motor  31 . A linear actuator  35  is operatively coupled to the drive motor  31  by a connected driven linear gear  34  and a drive belt  33  trained between the drive gear  32  and the driven linear gear  34 . The diameter of the drive gear  32  is preferably larger than the driven linear gear  34  to impart more relative rotations to the driven linear gear  34 . However, this gear ratio can be varied. An elongate, reciprocating actuator rod  36  extends from the linear actuator  35  and includes a bearing  36   a  at the distal end thereof. The bearing  36   a  is preferably a round bearing that secures and supports one end of the rotary push rod  37 , while permitting free rotation of the push rod  37  thereon. The push rod  37  can also be provided with a fixed circular bearing  37   a  to provide additional support or reinforce support at that end. A linear bearing  38  is mounted inside the corresponding airfoil  11   a ,  11   b  near the outer end of the airfoil  11   a ,  11   b . The linear bearing  38  supports the opposite end of the push rod  37  and permits the push rod  37  to reciprocate and rotate therein. 
     In use, rotation of the drive gear  32  rotates the driven linear gear  34  through their connection with the drive belt  33 . Although rotary, the driven linear gear  34  converts the rotary motion into linear movement of the actuator rod  36 , such as by a screw or threaded connection between the driven linear gear  34  and the actuator rod  36 . As the actuator rod  36  extends or retracts by the linear actuator  35 , the actuator rod  36  also pushes or pulls the push rod  37  through the connection to the bearing  36   a.    
     The linear and rotary movements of the push rod  37  force the split flap tie rods  40  to move in response. Each split flap tie rod  40  includes a lower pivot joint  40   a  coupled to the push rod  37  and an upper pivot joint  40   b  coupled to the corresponding split flap  12   a ,  12   b . Due to the compound motions of the split flap tie rods  40  during rising and lowering of the split flaps  12   a ,  12   b , the upper pivot joint  40   b  is connected to a hinge  42  on the underside of the corresponding split flap  12   a ,  12   b . This connection allows the split flap tie rod  40  to pivot about a horizontal axis, the axis being defined by the hinge  42 . The interconnection between the hinges  42 , the split flap tie rods  40 , and the push rod  37  forms a four-bar linkage parallelogram where the hinges  40  and their connection to the split flap  12   a ,  12   b  and the push rod  37  define the upper and lower bars of the parallelogram while the split flap tie rods  40  form the parallel side bars of the parallelogram. 
     In use, the push and pull movements of the push rod  37  laterally translates the split flap tie rods  40 . This causes the split flap tie rods  40  to pivot about the lower pivot joint  40   a  with respect to the push rod  37  in one direction, as well as about the upper pivot joint  40   b  with respect to the hinge  40  in the opposite direction. Since the dimensions of the parallelogram are fixed, except for the distance between back edge of the split flap  12   a ,  12   b  and the push rod  37 , the push rod  37  also rotates to force the split flap tie rods  40  to pivot the hinge  42 . It is noted that the rotation is not a full rotation within this configuration. Rather, the rotation is a relatively small arc. Thus, the upper and lower bars of the parallelogram are pushed apart to raise the split flap  12   a ,  12   b  and pulled to lower the split flap  12   a ,  12   b . It can be seen from this description that the movements of the parallelogram are not confined to a single plane. The pivoting afforded by the hinges  40  and the push rod  37  also translates the plane of the parallelogram within the arc of rotation. 
     The operation of the split flaps  12   a ,  12   b  is controlled by a controller  50 . The controller  50  includes lines  52   a ,  52   b  connected to the respective linear actuator assembly  30   a  in order to control deployment and angle of each split flap  12   a ,  12   b  independently and separately. The angle of rise for each split flap  12   a ,  12   b  can vary depending on various input parameters, such as acceleration, lateral gravitational force, steering position, throttle, speed, braking, and the like to improve the performance of the vehicle C. For example, the vehicle C shown in  FIG. 1  is performing a right turn. At relatively high speeds, a hard right turn will induce lateral forces that tend to lift the right side of the vehicle C, thereby increasing the potential for the right wheels to lose contact with the road, especially on non-banked roads. To compensate, the right split flap  12   b  on the right airfoil  11   b  opens to a specific angle to increase the angle of attack, which creates additional downforce on the rear right wheel for better grip on corners, which improves cornering speed. Moreover, at hard braking, both split flaps  12   a ,  12   b  can be fully deployed to increase drag and exert maximum downforce on the rear wheels RW to counterbalance load transfer to the front of the vehicle and the front wheels, which improves vehicle braking performance. Additionally, the potential assistance from the split flaps  12   a ,  12   b  permits installation of larger rear brake rotors for increased braking performance. In normal conditions, the split flaps  12   a ,  12   b  are closed and the airfoils  11   a ,  11   b  can function like regular airfoils. Thus, the airfoils  11   a ,  11   b  dynamically adjust their relative positions in a passive manner in response to the movements of the rear suspension system, while the split flaps  12   a ,  12   b  dynamically adjust their deployment angle, depending on the driving conditions and the input parameters. 
     The controller  50  can also be programmed to optimize performance of various vehicles C. In other words, the selective deployment of each split flap  12   a ,  12   b  and the angle of deployment can be tailored to individual vehicles. For example, vehicles of various makes and models exhibit different performance characteristics with respect to each other due to many factors, such as body design and aerodynamics thereof, engine specifications, tire specifications, etc. One vehicle may have excellent performance in one area and nominal performance in another, while the performance characteristics of a different vehicle may be completely different. Whatever the performance parameters may be for a vehicle, the parameters can be analyzed, especially during development, and the operations of the controller  50  can be tailored to the specific vehicle to improve performance thereof. 
     The controller  50  can also be configured to provide manual deployment of the split flaps  12   a ,  12   b . In some cases, a skilled driver may desire a more manual approach to attacking corners and braking, similar in concept to utilizing a hand brake during drifting. 
     Referring to  FIG. 5 , the dynamically adjustable airfoil system  10  also includes a latching mechanism  60  disposed on the underside of each airfoil  11   a ,  11   b . The latching mechanism  60  permits detachable mounting of the airfoil lift tie rod  24  from the corresponding airfoil  11   a ,  11   b  in order to move the airfoil  11   a ,  11   b  out the way and gain access to the rear hatch of the vehicle C, e.g., for servicing and maintenance. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.