Patent Application
20140069562
Not Applicable.
Not Applicable
1. Technical Field of the Invention
The present invention relates generally to a bicycle tire and more specifically to a bicycle tire configured and adapted to have superior aerodynamic characteristics designed to mitigate wind resistance and drag.
2. Description of the Related Art
Bicycles are widely used in all corners of the world. A bicycle may be employed as a general means of transportation, or alternatively, as a recreational device, wherein the rider utilizes the bicycle for purposes of enjoyment or exercise. The structure of a bicycle generally includes a frame and a pair of wheels connected to the frame. Each wheel is fitted with a tire, which extends circumferentially about the wheel, and provides traction with the riding surface (i.e., track, road, etc.).
One aspect of bicycle riding which has a direct effect on the performance of the bicycle is the aerodynamic drag created as the bicycle and the rider pass through the air. In particular, the aerodynamic drag caused by the bicycle and the rider lessens the speed obtainable for the cyclist for the effort expended in propelling the bicycle. At average speeds, aerodynamic drag is typically the largest resistive force acting on the bicycle, aside from the gravity of a large hill.
Bicycle designers and riders recognize the detrimental effect caused by aerodynamic drag, and thus, certain measures have been taken to reduce drag. One particular improvement for enhancing aerodynamic performance has been the recognition that the human body is not very streamlined, and therefore, body positioning has a critical impact on the aerodynamics. To this end, road cyclists commonly employ “drop bars” to allow themselves to reduce their frontal area, which helps reduce the amount of resistance they must overcome. In addition to cyclist positioning, other details, such as clothing, can make a significant impact in reducing “skin friction.” Tight-fighting clothing is worn by most cyclists for improvement in aerodynamics, as well as comfort.
In addition to improving the aerodynamics of the rider, other features have been implemented into contemporary bicycle designs to minimize the amount of drag created by the bicycle itself. Some recent frame designs have concentrated on creating a more streamlined frame design. Designers have also attempted to improve the aerodynamics of the bicycle wheels. Along these lines, a conventional spoked wheel creates many small eddies as the wheel rotates, which increases the drag. Thus, disc-wheels are often use, which produce less wind drag and turbulence as they spin.
One particular area of the bicycle which has not been given much consideration for its aerodynamic impact is the bicycle tire. In view of the fact that the bicycle tire circumnavigates the wheel, the bicycle tire defines a leading edge which directly interfaces with the air as the bicycle moves. Thus, the tire has an immediate impact on the overall aerodynamics of the bicycle.
Most conventional tires define a generally circular outer surface taken within at least one cross section. In this regard, the generally circular outer surface defines a generally constant radius about a central axis. As the tire passes through the air, the generally circular outer surface separates the air into two separate, diverging air flows. The divergent nature of the separate air flows increases the wind resistance and drag on the bicycle, and thus, reduces the overall aerodynamics thereof.
Therefore, there is a need in the art for an improved bicycle tire designed to have reduced drag and wind resistance relative to conventional bicycle tires. Various aspects of the present invention address these particular needs, as will be discussed in more detail below.
The present invention specifically addresses and alleviates the above-identified deficiencies in the art. Along these lines, there is provided a bicycle tire for use with a bicycle wheel. The bicycle tire includes a tire body defining a closed loop and being configured to be engagable with the bicycle wheel. The tire body defines an outer periphery and includes an exposed portion extending radially outward from the bicycle wheel when engaged therewith. The exposed portion is externally configured so as to define a partial, non-circular ellipse in a cross sectional plane perpendicular to the tangent of the outer periphery. The partial ellipse includes a closed end portion at the outer periphery and an open end portion adjacent the bicycle wheel. The tire includes separately, or in combination with the aforementioned tire body, a plurality of nubs attached to the tire body, with the nubs being configured to remain attached thereto during the life of the bicycle tire. The nubs are sized and configured to enhance the aerodynamics of the bicycle tire as the tire rotates and translates through a fluid.
The unique external configuration of the bicycle tire provides improved aerodynamic qualities relative to conventional bicycle tires. Along these lines, the oblong, elliptical shape of the tire body allows the tire body to slice through the air to minimize disruption of the air, which in turn reduces drag and wind resistance. The placement and configuration of the nubs provides additional aerodynamic benefits to the bicycle tire.
The plurality of nubs may be integrally formed with the tire body. The exposed portion may include a first lateral portion and an opposing second lateral portion, wherein the plurality of nubs may include a plurality of first nubs connected to a first lateral portion of the tire body and a plurality of second numbs connected to the second lateral portion of the tire body. The plurality of first nubs may be equally spaced relative to each other, and the plurality of second nubs may be equally spaced relative to each other. The plurality of nubs may be angled relative to the tire body toward the outer periphery as the nubs extend away from the tire body.
The closed end portion may terminate at a distal end, such that the exposed portion may define a cross sectional length equal to the distance between the wheel and the distal end, and a cross sectional width equal to the maximum distance between opposed lateral ends of the exposed portion, wherein the cross sectional length is greater than the cross sectional width. The exposed end portion may define a variable cross sectional radius of curvature in the cross section taken in a plane perpendicular to the tangent of the outer periphery. The radius of curvature may be greatest along a first axis which divides the closed end portion into two symmetrical halves, and shortest along a second axis perpendicular to the first axis.
The present invention is best understood by reference to the following detailed description when read in conjunction with the accompanying drawings.
These as well as other features of the present invention will become more apparent upon reference to the drawings wherein:
Common reference numerals are used throughout the drawings and detailed description to indicate like elements.
The detailed description set forth below is intended as a description of the presently preferred embodiment of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the functions and sequences of steps for constructing and operating the invention. It is to be understood, however, that the same or equivalent functions and sequences may be accomplished by different embodiments and that they are also intended to be encompassed within the scope of the invention.
Referring now to the drawings, wherein the showings are for purposes of illustrating a preferred embodiment of the present invention, and not for purposes of limited the same, there is shown a bicycle tire 10 constructed in accordance with an embodiment of the present invention. The bicycle tire 10 is specifically configured and adapted to have improved aerodynamic characteristics, particularly when compared to conventional bicycle tires, wherein the improved aerodynamics yields a reduced drag and wind resistance. As will be described in more detail below, the primary structural features which contribute to the improved tire aerodynamics are the elliptical shaped cross-section of the tire 10 (see
Referring now specifically to
Each wheel 24 includes a central hub 28 connected to a peripheral rim 30 via a plurality of spokes 32 which extend radially between the rim 30 and the hub 28. Each wheel 24 defines a respective axis of rotation about which the hub 28 and rim 30 are disposed and rotate. The rim 30 defines an inner diameter and an outer diameter. According to one embodiment, the rim 30 defines a conventional U-shape including a closed end portion adjacent the inner diameter and an open end portion adjacent the outer diameter (not shown). The open end portion defines a rim slot extending around the outer circumference of the rim 30 and configured to facilitate engagement with the tire 10.
The bicycle 12 includes a pair of tires 10 engaged with respective ones of the front and rear wheels 24, wherein each tire 10 includes a tire body 34 (See
When the tire body 34 is engaged with the wheel 24, the tire body 34 defines an exposed portion 36 (see
Referring now specifically to
The external surface of the exposed portion 36 defines a non-circular, partial elliptical shape in a cross section taken within a plane that is perpendicular to the tangent of the outer periphery of the tire body 34. The partial elliptical shape defines a variable radius of curvature which produces the non-circular configuration. The exposed portion 36 includes a closed end portion defining a generally parabolic shape adjacent an outer periphery of the tire body 34, and an open end portion disposed adjacent the rim 30 when the tire body 34 is engaged to the rim 30. In this regard, the cross section of the exposed portion 36 does not form a complete, closed ellipse.
The aerodynamic benefits realized by the tire 10 are at least partially attributable to the non-circular partial elliptical shape of the exposed portion 36 of the tire body 34. For purposes of comparison, reference is now made to
The circular configuration of the prior art tire 10a creates an aerodynamic effect which pushes fluid away from the tire 10a as the tire 10a passes through the fluid. The phantom lines shown in
Conversely, various aspects of the present invention are directed toward creating an improved aerodynamic condition which mitigates the degree of fluid separation as the tire 10 advances through the surrounding fluid, i.e., air. Turning now to
The beneficial aerodynamic characteristics are at least partially attributable to the unique configuration of the tire body 34. More specifically, the exposed portion 36 of the tire body 34 is a non-circular, elliptical shape wherein the magnitude of the radius of curvature from the center of the ellipse varies. In the exemplary embodiment shown in
As can be seen, as the tire 10 is advanced through the fluid, the fluid separates into two separate, but parallel flow paths, wherein the space between the flow paths is substantially equal to the width W2. The unique configuration of the exposed portion 36 of the tire body 34 minimizes the amount of displacement of the fluid flow paths, which results in a beneficial aerodynamic effect.
Another beneficial aerodynamic feature of at least one embodiment of the tire 10 relates to the plurality of nubs 14 connected to the exposed portion 36. The nubs 14 may be coupled to one, but preferably both sides or lateral portions of the exposed portion 36 of the tire body 34 and may be spaced adjacent the circumference of the tire body 34. In the embodiment shown in
The nubs 14 may be specifically configured and adapted to remain connected to the tire body 34 throughout the normal life of the tire 10. According to one embodiment, the nubs 14 may be integrally formed to the tire body 34 through a molding process. More specifically, the mold may define a cavity which substantially conforms to the size and shape of the tire body 34, such that when a molding material is poured or transferred into the mold cavity, the molding material assumes the shape of the tire body 34. The mold may additionally include a plurality of vent holes connected to and extending from the mold cavity, wherein the vent holes are configured to prevent the formation of air bubbles within the molded tire body 34. In particular, as the molding material fills up the mold cavity, the vent holes allow air to escape the mold cavity. When the mold cavity is filled, the excess molding material bleeds into the vent holes and forms the plurality of nubs 14. Thus, when the molding material hardens, the nubs 14 are integrally formed with the tire body 34.
The nubs 14 may also be formed through transfer holes used in the molding process. In particular, the molding process may utilize a mold and a reservoir of rubber material, wherein the rubber material is transferred from the reservoir into the mold via a plurality of transfer holes. The nubs 14 may be formed from excess rubber material contained within the transfer holes at the end of the molding process.
According to one embodiment, the nubs 14 extend out from the tire body 34 and are angled toward the outer circumference of the tire body 34, although it is understood that the particular orientation of the nubs 14 is not limited thereto. In this regard, the nubs 14 may extend from the tire body 34 along a common axis in opposed directions, or toward the inner circumference of the tire body 34. Furthermore, the length, diameter, and shape of the nubs 14 may be varied to enhance the aerodynamic effect created thereby. In this regard, the nubs 14 are not limited to the particular round/cylindrical configuration depicted in the figures; other embodiments may include nubs 14 that are triangular, quadrangular, etc. Moreover, the size of the nubs 14 may be increased to provide more structural rigidity to ensure the nubs 14 remain connected to the tire body 34 during the normal life of the tire 10, under normal operating conditions.
The various structural attributes, including the partial elliptical, non-circular shape of the tire body 34, as well as the plurality of nubs 14, may be used on any size or diameter of wheel 24. Furthermore, it is also understood that other aerodynamic enhancement features may be incorporated into the tire 10. For instance, the tread formed on the tire 10 may define a specific configuration which enhances the aerodynamics of the tire 10 by minimizing the degree of separation of the fluid flow paths around the tire 10. Along these lines, the tread design may be integrated into the desirable elliptical shape of the tire body 34.
Furthermore, although the foregoing discussion and the related drawings pertain to an embodiment of the tire 10 including both an elliptical, non-circular shape, as well as a plurality of nubs 14, it is understood that other embodiments may include one or the other, not necessarily in combination with each other. More specifically, one embodiment may include a plurality of nubs 14 on a tire 10 that does not define a non-circular elliptical shape, while another embodiment of the tire 10 may define a non-circular elliptical shape, without a plurality of nubs 14.
Although foregoing describes a bicycle tire, it is contemplated that other aspects of the present invention may relate to other types of tires for other wheeled devices, including but not limited to, unicycles, wheelchairs, motorcycles, automobiles, tractors, go-carts or the like.
Additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art. Thus, the particular combination of components and steps described and illustrated herein is intended to represent only certain embodiments of the present invention, and is not intended to serve as limitations of alternative devices and methods within the spirit and scope of the invention.
