Land vehicles: bodies and tops – Bodies – With distinct wind deflector
Reexamination Certificate
2001-10-19
2003-10-28
Dayoan, D. Glenn (Department: 3612)
Land vehicles: bodies and tops
Bodies
With distinct wind deflector
C180S903000
Reexamination Certificate
active
06637805
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a safety apparatus for vehicles traveling at high speed. In particular, the invention relates to an apparatus particularly suited for competitive racing vehicles that directs air into a vehicle that is yawed from a forward path of travel in such a manner to exert an increased downward force on the surfaces of the vehicle. The invention further relates to a method of directing air into a yawed vehicle traveling at high speed to exert a downward force on the vehicle.
BACKGROUND OF THE INVENTION
Automobile racing, and in particular racing sanctioned by the National Association for Stock Car Auto Racing (NASCAR), has become one of the most competitive sporting events in the United States. NASCAR is currently the fastest growing spectator sport in the U.S. whose average annual attendance grew by 65% within the period 1990-1997. Moreover, NASCAR is the only professional sport that enjoyed increased growth in its television audience during the 1990's. Revenues for NASCAR approached $2.2 billion in 1999, placing NASCAR third behind the National Football League (NFL) and Major League Baseball (MLB) in operating income and ahead of the National Basketball Association (NBA) and National Hockey League (NHL). In 2000, NASCAR signed a $2.4 billion, six-year television contract with NBC, FOX, and Turner Sports. The contract placed NASCAR ahead of Major League Baseball, National Basketball Association, and National Hockey League in terms of average annual television revenues. Moreover, NASCAR is second only to the NFL among televised sporting events in the U.S. In 1998, NASCAR generated more than $1.1 billion in sponsorship revenues, which is more than double the combined revenue of the NBA, NFL, NHL, and MLB.
The increased popularity in racing has led to an influx of economic sponsorship, and hence an increase in the amount of money invested in the research and development of racing vehicles. As a result of the technological improvements in the design of racing vehicles and engines, the speeds at which the vehicles race has increased dramatically over the years. During the 1980's and 1990's, Winston Cup cars achieved speeds of over 200 miles per hour (mph). Because of safety concerns, NASCAR sought a number of practices to reduce speed and increase safety.
One such practice was the incorporation of a restrictor plate (i.e., a thin aluminum plate that fits between the carburetor and the intake manifold of the engine) into the engines to reduce speeds and hence increase the likelihood of a driver surviving a major crash. Subsequently, NASCAR approved the use of aerodynamically responsive roof flaps that are affixed to the tops of vehicles. The roof flaps as described in U.S. Pat. Nos. 5,374,098 and 5,544,931 to Nelson actuate upwards when the vehicle becomes yawed from the forward path of travel (i.e., spins) to present a vertical surface to the flowing air, thereby increasing drag and reducing the speed of the spinning vehicle. As used herein, it will be understood that the term “forward path of travel” means the direction that a vehicle is moving when operated under normal conditions such that the longitudinal axis of the vehicle is parallel to the track and the front of the car is facing forward. Likewise, a direction yawed from a forward path of travel means the longitudinal axis of the vehicle is rotated about its vertical axis, as occurring during a spin.
Despite improved safety features, the likelihood of driver injury during a crash at speeds of over 180 mph remains high. Furthermore, the recent death of Dale Earnhardt, one of the most successful and most popular drivers, has elevated safety concerns to a top priority with NASCAR.
The underlying goal of racing, that is, faster speeds, frustrates ongoing safety efforts. It will be understood by those familiar with competitive racing that conventional racing vehicles are designed to achieve the fastest speeds within the regulatory regime of a sanctioning body, such as NASCAR. In other words, the body structure of the vehicle is designed to present the least amount of aerodynamic drag, while providing the greatest amount of downward force (or “down force”) on the vehicle while the vehicle is traveling in a forward path of travel.
In addressing safety and performance considerations, designers must consider the four physical forces acting on a moving vehicle. In aerodynamic terms, these forces are expressed by lift (L) which acts perpendicular to the forward path of travel, drag (D) which acts parallel to the forward path of travel, weight (W) which acts vertically towards the center of the earth, and thrust (T) which acts parallel to the forward path of travel. Thrust, provided in this case by a vehicle engine, is counteracted by drag created by the flowing air traveling along the vehicle surfaces. Lift created by the air flowing under the vehicle and over contoured surfaces is counteracted by the weight of the vehicle, and any aerodynamic force created by the vehicle body and spoilers or air dams on the vehicle surface.
As air flows along the contoured surfaces of a vehicle, different velocities are produced. In turn, these varying velocities produce differential pressures that are distributed over the surface of the vehicle. More specifically, the aerodynamic pressures acting over a particular area produce an aerodynamic force. Aerodynamic force is a function of pressure acting over a surface area. In order to produce down force, it is desirable to produce higher pressure on the top side of the vehicle in order to produce lower pressure on the underside of the vehicle. Furthermore, aerodynamic pressure ideally acts over a substantially horizontal area to generate a down force or negative lift. For example, aerodynamic lift on a vehicle is primarily generated over horizontal areas such as the engine hood, roof, rear deck (or trunk lid), and the underside of the vehicle. Conversely, to create aerodynamic drag, aerodynamic pressure ideally acts over a substantially vertical area. For example, drag is influenced strongly by the pressures acting on the rear spoiler.
As described, aerodynamic down force is an important factor affecting the performance and safety of high-performance racing vehicles. In regards to performance and handling, an increase in down force acting on the vehicle also improves the handling of the vehicle at high speeds and especially in turns. For example, if the air flow is separated or “departs” from the rear deck of a vehicle during a turn, the down force decreases and the rear end tends to slide as the vehicle rotates about a vertical axis, thereby causing the vehicle to become yawed with respect to the forward path of travel. In order to produce down force, horizontal airflow resulting from a vehicle in motion must be redirected upwards. As applied to a Winston Cup car, the spoiler on the rear deck of the vehicle redirects the air upward and increases the down force on the rear end of the vehicle. In order to maximize rear end down force, analysis indicates that the aerodynamic down force acting on the vehicle should be as far to the rear as possible.
In regards to safety, it is desirable to create the maximum amount of down force on a vehicle during high-speed backward movement or a spin to prevent a vehicle from flipping or becoming airborne. Specifically, an increase of down force on a yawed vehicle can prevent the vehicle from flipping upon entering a high-speed spin. Most devices are designed to produce down force on a vehicle traveling in a forward path of travel. Thus, during a spin, these devices may actually produce lift, which tends to destabilize a spinning vehicle. Thus, it is necessary to provide a device that can increase down force on a yawed vehicle that does not negatively affect the aerodynamics of a vehicle traveling in a forward path of travel.
As noted, conventional racing vehicles include aerodynamically designed spoilers, air dams, and other air spoiling devices for increasing the amount of down force acting on a vehicle traveling
Chenevert Paul
Summa & Allan P.A.
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