Patent Application
20130096781
The present invention relates generally to automotive vehicle aerodynamics and more particularly to an apparatus associated with an automotive vehicle wheel.
There are many aerodynamic inefficiencies associated with rotating wheels of a traditional automotive vehicle. For example, a ball of high pressure turbulent air is created at the front of each wheel where it meets the road thereby creating drag on the vehicle. Furthermore, the wheelhouse, wheel rim and wheelhouse opening in the fender also cause turbulent air flow. For example, turbulent air flow vortices are caused by separation of an air boundary layer developed at outer edges of a conventional wheelhouse arch. A downward air flow is also present in front of the conventional rotating wheel; this causes a high pressure region or ball of air at the wheel-to-road contact point. A strong C-shaped vortex is originated by the interaction of downward flow and the separation of a lateral flow of a boundary layer at the wheel from this high pressure area. An additional upward flow interacts with a boundary layer separation of the wheel. Among others, vortices are created at the rear part of the wheel between the C-shaped vortex and the road but are of less intensity than the C-shaped vortex. It is noteworthy that increases in conventional wheelhouse depth increase the total drag and total downforce, while conventional rotating wheels generate lift and considerable drag. Therefore, it is believed that traditional wheels cause about eight percent of the total vehicle drag. This is especially problemmatic as greater vehicular fuel efficiency and energy range are desired.
Various concepts have been considered for covering the wheelhouse opening. For example, reference should be made to the following U.S. Pat. No. 1,989,368 entitled “Motor Vehicle” which issued to Knapp on Apr. 26, 1933; U.S. Pat. No. 2,010,359 entitled “Automobile” which issued to Davis on Aug. 6, 1935; and U.S. Pat. No. 2,349,421 entitled “Front Fender Shield” which issued to Green on May 23, 1944. These patents are incorporated by reference herein. These traditional devices, however, are very complicated, undesirably take up space, and add significant weight through additional rods, turnbuckles and bars which defeat fuel savings due to aerodynamic improvements; some of these attempt to mechanically move a center of an apron or skirt which is geometrically difficult especially due to wind resistance at high speeds. Moreover, traditional devices still do not reduce much of the circumferential aerodynamic turbulence caused by the wheel rotation.
In accordance with the present invention, an automotive vehicle wheel apparatus includes a turnable cover or door for a front wheelhouse opening in a fender. In another aspect, a sheath or liner is provided close to at least half of a circumference of a wheel. A further aspect blocks and/or removes circumferential air moving with a wheel. Yet another aspect connects an actuator adjacent a front and/or rear edge of a wheel cover so as to turn the cover with the wheel. In still another aspect, an electronic controller causes turning of a cover with a wheel. A method of operating an automotive vehicle, including reducing aerodynamic turbulence, is also provided.
The present apparatus is advantageous over traditional approaches. For example, the present apparatus reduces circumferential wheel air turbulence. Additionally, the present apparatus reduces wheel hub and wheelhouse opening air turbulence. The present apparatus also advantageously provides a much simpler, more cost effective, smaller and lighter weight mechanism to turn a wheel covering door. These aerodynamic and weight saving benefits are ideally suited for electrically driven vehicles in order to improve their operating range or distance for a given amount of stored energy. Additional features and advantages of the present apparatus can be ascertained from the following description and appended claims.
Referring to
Automotive vehicle 21 is preferably electrically powered for its traction-driving power to wheels 23. For example, an electric traction motor 57 is provided, although it is also envisioned that a hybrid electric/internal combustion engine, fuel cell or other such primarily electrically driven motor can be employed. Such an electrically driven vehicle places a premium on employing light weight components and a low aerodynamic coefficient of friction in order to obtain an acceptable operating range, such as at least 100 miles of distance for a single battery charge operating at at least 50 miles per hour. It is expected that the present apparatus will assist in achieving these performance characteristics.
The vehicular body includes a fender 81 mounted to a wheelhouse 51, which defines a wheelhouse opening 83 therein. A rigid wheel cover or door 85 is located within and has a peripheral edge that mirrors each wheelhouse opening 83. An inwardly turned lateral wall or lip may be optionally located at the periphery of cover 85. A small and generally uniform gap is longitudinally (fore-and-aft) defined between the peripheral edge of cover 85 and an internal edge of wheelhouse opening 83. Moreover, cover 85 is laterally (cross-car) spaced from and hides a majority of wheel 23 from outside the vehicle when in a nominal, straight forward driving condition. Cover 85 is preferably made from an injection or compression molded polymeric material such as TPO or RIM, but may alternately be made from a layered composite material, a long strand and resinated fiber material such as fiberglass sheets, resinated fabric, or less preferably a stamped metallic sheet such as aluminum. Cover 85 is thereafter painted to match the exterior of the automobile.
Wheel cover 85 is coupled to an inside surface of either wheelhouse 51 or fender 81 by way of a central swivel joint 91 consisting of a ball and socket. For example, a ball is mounted on a stem upstanding from a bracket 93 fastened to or integrally molded to a backside of cover 85. This allows joint rotation or turning of cover 85 from a nominal straight forward position to left and right turned positions 85A and 85B, respectively, as shown in
An offset stepped flange 97 extends from the backside surface of wheel cover 85 adjacent a front edge 99 of the wheel cover and an offset stepped flange 101 is similarly mounted to the backside of cover 85 adjacent a rear edge 103 thereof. The longitudinal sections of flanges 97 and 101 are overlapping behind each respective fender. Each flange has a hole therein through which a stationary stem 105 extends. The stem is affixed to a backside of either the wheelhouse or fender and projects in a generally lateral direction terminating in a large head 107. A compression spring 109 is mounted between head 107 and flange 97 while a second compression spring 111 is mounted between the fender or wheelhouse and flange 97. These compression springs sandwich and center flange 97 therebetween thereby biasing cover 85 to the nominally oriented position. A similar arrangement is provided for flange 101. Alternately, however, leaf springs, extension springs, elastomeric pads or other such members can be used to bias the offset flanges 97 and 101, although certain benefits may not be achieved.
Referring now to
A rear segment of sheath 121 includes a longitudinally elongated duck bill shape 125. An inwardly extending wall 127, integrally formed inside sheath 121, is forwardly and downwardly directed toward the wheel from its proximal end joining sheath 121. A distal end of wall 127 is within ¾ inch from the outside diameter of the tire. Wall 127 acts as an aerodynamic scoop to remove and peel off the circumferential boundary layer air being dragged around by rotation of wheel 23. The duck bill shape 125 further channels the removed air 129 away from the wheel and wheelhouse area.
The close dimension of front lower edge 123 of sheath 121 serves to block air flow 131 otherwise hitting wheel 23 during high speed vehicular operation. This also deters the high pressure air vortex from forming at the front of the tire thereby avoiding much of the drag at the wheel-to-road contact point. Furthermore, the close radial distance between sheath 121 and the outside diameter of wheel 23 deters circulation losses of the tire in the wheelhouse otherwise due to moving boundary layer air caused by the tire tread and the turbulent air flow drag otherwise created by traditional interactions of this air with the wheelhouse.
Sheath 121 has a somewhat inverted U-shape when viewed in a side elevation (like
During operation at high speeds, such as above 50 miles per hour, there is enough lateral clearance between an outside surface of sheath 121 and an inside surface of wheel cover 85 so as to allow approximately 5-10 degrees of steered turning movement a without requiring movement of wheel cover 85 from its nominal position. This enhances high-speed aerodynamics by providing a continuous and uninterrupted air flow pattern along the adjacent outside vehicle surface. At slower speeds and for more abrupt steering at faster speeds, steered rotation of the wheel causes a front side corner or rear side corner of sheath 121 to contact against and push open the corresponding portion of wheel cover 85. Springs 105 and 111 will cause cover 85 to return to its nominal position when the wheel and sheath are straightened back out and the contact is removed from the cover. Optionally, a rotatable ball 141 and race 143, such as a ball bearing device, are attached to either sheath 121 or cover 85 to provide the contact points therebetween.
Joints 157 are attached to rigid links. The present embodiment employs a Robert's straight line motion, four-bar linkage 151. The cross-car lateral distance between joints 153, attached to an upright or arm of the suspension to the joint 155 of wheel cover 85, is a fixed distance for a given range of motion which allows the wheel to move vertically independent of the wheel cover. The wheel cover, however, will follow wheel 23 when its steering angle is changed. This system avoids the need for a sheath to push against the wheel cover and also avoids the need for a cover biasing mechanism.
Another embodiment of the present apparatus is illustrated in
An electric motor actuator 185 pushes and pulls cables 177 and 183 into and out of the cable drum for turning door 85. Furthermore, an electronic control unit or body computer 191 is electrically connected to motor 185 by an electrical circuit 193. Programmed computer instructions within non-transient memory, such as RAM, ROM or the like, of electronic control unit 191 operably receive a velocity signal and a steering angle signal from an optional electrical velocity sensor 195 and a steering shaft sensor 197, respectively, based on operating conditions of the vehicle. The electronic control unit then automatically compares the real time received velocity and steering angle signals and compares them to previously stored threshold signals in the memory. Next, the electronic control unit calculates and determines if electric motor 185 should be energized or de-energized to automatically turn wheel cover 85 to allow desired clearance for steering of wheel 23 optionally depending upon the vehicular speed.
Referring now to
A sheath or liner 221 closely covers at least an upper half of wheel 223 as in the first embodiment. An illumination source 233, preferably an elongated string containing multiple connected light emitting diodes, is secured within a trough 235 of wall 225 of the wheel cover. A rivet, Christmas tree-type push pin or other fastener 237, is used to retain the LED string within trough 235. The LED string is at least twenty times longer than wide in any cross-sectional direction. Furthermore, an elongated reflector 239 is affixed inside wheelhouse 251 so as to outwardly reflect light emanating from illumination source 233. Reflector 239 is either adhesive backed reflective tape or a polymeric rigid device. This lighting arrangement provides an aesthetically attractive illuminated gap along the entire periphery between wheel cover 285 and fender 281. This can also serve as a side marker lamp to enhance traffic safety.
An electrical wire 261 connects a stored power source, such as a battery 263, to illumination source 233. In order to do this, wire 261 is fed from the battery compartment, within the vehicular body, through swivel joint 91 which has a hollow center and to a backside of wheel cover 285. As an alternative, such a wire routing configuration can be used to supply electricity to a light emitting diode or an incandescent light bulb mounted to the exterior, generally vertically planar surface of wheel cover 285 to either illuminate a brand name on an aesthetically pleasing ornamental trim piece or as a functional side marker lamp. It is also envisioned that a reflector may not be necessary.
While various constructions of the present wheel apparatus have been disclosed herein, other variations can be made. For example, solenoid or fluid powered actuators can be employed to move the wheel cover instead of an electric motor, although various advantages of the present apparatus may not be achieved. Additionally, the wheel sheath may be used without an external wheel cover or vice-versa, although certain benefits will not be realized. The wheel cover and/or sheath can also be used for the rear wheels. Moreover, the disclosed connecting rods and/or cables can be replaced by cables, links, belts or other devices although certain advantages will not be obtained.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.
