Not applicable.
1. Field of the Invention
The invention relates generally to apparatus and methods for personal transportation. More particularly, the invention relates to a skateboard.
2. Background of the Invention
Skateboards have been used for many years as personal transportation and/or recreational devices. Most conventional skateboards include a flat wooden deck, two trucks mounted to the underside of the deck, and a pair of wheels mounted to hangers extending from each truck.
To propel the skateboard, the user typically places one foot on the deck, and uses the other foot to push against the ground. To turn the board, the user usually places both feet on the board and then exerts a portion of his/her weight on the side or edge of the board that faces the direction of desired turning. For instance, to turn left, the user would exert a portion of his/her weight on the left side of the board. The downward force exerted on the one side of the board compresses a bushing in the trucks that results in the slight pivoting of the wheels relative to the board, thereby enabling turning. In general, the greater the force exerted on the side of the deck, the sharper the turn and smaller the turning radius. Thus, in many cases, a relatively sharp, quick turn requires a substantial portion of the user's weight to be exerted on the side of the deck, often necessitating both feet be positioned on the deck. However, with both feet positioned on the board, the user is unable to push against the ground to continue propelling the board. In other words, in many cases, the user must choose between propelling the board by pushing against the ground with a foot or turning the board by standing on the deck with both feet, but not both simultaneously.
Many conventional skateboards have a relatively small diameter wheels, typically between one and three inches in diameter, and are often made of a relatively hard rubber material. Due to their relatively small diameter, conventional skateboard wheels tend to be susceptible jamming should they roll into a stone or other small object. Should a wheel suddenly jam or stop rotating, the deck may abruptly stop, potentially resulting in injury to the user. Further, hard durometer rubber wheels typically result in a rough ride, particularly, over slightly uneven terrain. Moreover, most conventional skateboard wheels are positioned between the deck and the ground, and do not extend beyond the outer perimeter of the deck. Therefore, the distance between the two wheels mounted to a given truck tends to be relatively short, resulting in a relatively narrow wheelbase. In general, the narrower the wheel base, the less stable the board and the more susceptible the board to flipping on its side, particularly during turning.
Accordingly, there remains a need in the art for an improved skateboard. Such a skateboard would be particularly well received if it offered the potential for improved stability and handling, and was capable of being steered with relative ease.
For a detailed description of some of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:
The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.
Certain terms are used throughout the following descriptions and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.
In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . . ” In addition, the term “couple” or “couples” is intended to mean either an indirect or a direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. As used herein the terms “axial” and “axially” refer to positions and movement measured parallel to a central axis, whereas the terms “radial” and “radially” refer to positions and movement measured perpendicular to a central axis.
Referring now to
Body 20 is a generally elongate board that supports the user of skateboard 10 (i.e., one or both feet of the user are positioned on body 20). Body 20 has a longitudinal axis 25, a first or front end 20a, and a second or rear end 20b. In addition, body 20 includes an upper or top surface 23, a lower or bottom surface 24 opposite upper surface 23, and lateral sides or edges 22, extending between surfaces 23, 24. In this embodiment, top surface 23 includes a raised rib or protrusion 29 that extends perpendicularly to axis 25 across body 20 proximal rear end 20b. Raised rib 29 preferably extends to a height between 0.125 inches and 0.5 inches measured perpendicularly from upper surface 23, and has a width between 0.125 inches and 0.375 inches measured perpendicularly to axis 25 in top view. Raised rib 29 provides tactile feedback to the user of skateboard 10 when the user's foot gets too close to rear wheels 50, thereby offering the potential to reduce the likelihood of the user inadvertently contacting rear wheels 50 with his/her foot. Top surface 23 may also comprise a textured surface such as ridges, waffle grids, sandpaper, or the like to enhance friction and grip between top surface 23 and the user's foot.
In this embodiment, each lateral side 22 includes a tapered portion 28 at front end 20a, and a cutout 27 at rear end 20b. Tapered portions 28 provide space for front wheels 30 to turn or pivot relative to board 20 such that front wheels 30 do not contact board 20 during turns. Cutouts 27 accommodate rear wheels 50 and provide space for rear wheels 50 to turn or pivot relative to board 20 such that rear wheels 50 do not contact the board during turns.
Referring still to
As best seen in
In general, body 20 may comprise any suitable material including, without limitation, metals or metal alloys, polymers, composites, or combinations thereof. However, body 20 preferably comprises a relatively lightweight and durable material with sufficient strength to withstand the anticipated vertical loads. An example of such a material is polypropylene. In this embodiment, the material composition of body 20 and the convex geometry of body 20 are configured such that body 20 will flex about 1 to 1.25 inches under the weight of a 150 lb. to 17-lb. user.
Referring still to
Both front wheels 30 have the same diameter Df. Diameter Df is preferably greater than about 4 inches, more preferably between about 5 inches and about 7 inches. In this exemplary embodiment, front wheels 30 have a diameter Df of about 6 inches. As compared to most conventional skateboards having wheels with a diameter between 1 inch and 3 inches, wheels 30 with larger diameter offer the potential for a more stable skateboard 10 that is less likely to abruptly stop when wheels 30 contact and attempt to roll over small objects such as stones. Wheels 30 preferably comprise a relatively soft, durable material such as rubber at their outer radius. Such materials offer the potential for a smoother ride for the user of skateboard 10. Wheels 30 preferably have a relatively large aspect ratio, where the aspect ratio is the ratio of the diameter Df to the width of each wheel 30 measured parallel to axis 35. A relatively large aspect ratio offers the potential to reduce rolling resistance, while providing a smooth ride and the capability to roll over surface imperfections without wheels 30 jamming.
Referring now to the
Coupling member 40 rotates about the axis 45 such that front wheels 30 remain contacted with ground 11 when body 20 rotates about the board axis 25. When a force is exerted on one side 22 of body 20, that side is permitted to move toward ground 11 as body 20 rotates about its axis 25. As side 22 rotates towards the ground, front axle 34, and hence front wheels 30, pivot about ball and socket assembly 47, thereby turning front wheels 30 relative to body 20 and axis 25. In particular, wheels 30 pivot or turn towards the lowed side or edge 22 of body 20. Thus, for example, to execute a right hand turn, a downward force (e.g., the user's weight) is exerted on right edge 22, thereby rotating right edge 22 downward about axis 25, resulting in front wheels 30 pivoting about assembly 47 toward the right. In some embodiments, one or more torsional springs or other device may be included in front coupling member 40 to provide some level of resistance to the free rotation of coupling member 40 about axis 25.
As compared to some conventional boards that require significant downward force to compress a bushing in a truck, embodiments of front coupling member 40 offer the potential for turning and steering of skateboard 10 with less exertion of downward force, or load. Consequently, embodiments of skateboard 10 may be turned with exertion of force by a single foot of the user, thereby enabling turning and propulsion of the skateboard simultaneously.
Referring still to the side partial cross-sectional view of
Without being limited by this or any particular theory, based on the configuration and dynamics of coupling member 40, when angle θf is about 45°, the steering ratio of front wheels 30 is about 1:1. In other words, for every one degree of rotation of board 20 about its axis 25, front axle 35 and front wheels 30 pivot about one degree relative to axis 25. When angle θf is increased above 45°, the steering ratio increases above 1:1, but when angle θf is decreased below 45°, the steering ratio decreases below 1:1.
Without being limited by this or any particular theory, as convex body 20 flexes or deflects under the weight of the user, angle θf slightly increases, thereby increasing the steering ratio of front wheels 30. Thus, the greater the weight of the user, the more body 20 flexes, and the greater the increase in the steering ratio of front wheels 30. Increasing the steering ratio of front wheels 30 reduces the angle through which body 20 must rotate about axis 25 in order to achieve a particular front wheel 30 pivot angle. This may be particularly advantageous to heavier users who likely have larger feet; reduced rotation of body 20 about axis 25 to achieve the desired pivot of front wheels 30 offers the potential to reduce the likelihood of the users heel or toes contacting the ground 11 while turning.
Referring still to
Discs 46a, 46b may be axially spaced apart sufficiently to be rotated relative to each other and relative to body 20 to achieve the desired angle θf by loosening or decoupling releasable attachment member 42 from body 20. Once discs 46a, 46b are aligned as desired, attachment member 42 may be re-coupled to body 20 and tightened to sufficiently hold discs 46a, 46b in place so that the desired angle θf is maintained during use of skateboard 10. Wedged discs 46a, 46b are preferably rigid to maintain the desired angle θf. Moreover, the interfacing surfaces of discs 46a, 46b preferably comprise material(s) with a relatively high coefficient of friction or mating engagement mechanism (e.g., mating notches and recesses) that restrict the rotation of discs 46a, 46b relative to each other once aligned as desired and compressed into each other via attachment member 42.
As shown in
Referring again to
Rear axle 54 is disposed at a vertical distance or height hr measured perpendicularly from the ground 11 to axis 55. In this embodiment, rear-axle height hr is substantially the same as front-axle height hf. Similar to front wheels 30, wheels 50 are disposed such that rear axle height hr is greater than the body height hb, thereby allowing body 20 to be positioned closer to the ground and lowering the center of gravity of the user of skateboard 10 as compared to most conventional skateboards. Both rear wheels 50 have the same diameter Dr. Rear wheels 50 are preferably sized similar to front wheels 30 previously described.
Referring still to
Coupling member 60 rotates about axis 65 such that the rear wheels 50 remain contacted with the ground when body 20 is rotated about body axis 25. When a force is exerted on one side 22 of body 20, that side is permitted to move toward ground 11 as body 20 rotates about its axis 25. As that side 22 rotates towards the ground, rear axle 54, and hence rear wheels 50, pivot about the rear ball-and-socket assembly 67, thereby turning rear wheels 50 relative to body 20 about axis 65. In particular, wheels 50 pivot or turn away from lowed side or edge 22 of body 20, and work in conjunction with front wheels 30 to steer board 10. Alternatively, rear wheels 50 turn in opposite direction of front wheels 30 to steer board 10.
Referring now to
As with angle θf previously described, as convex body 20 flexes or deflects under the weight of the user, angle θr slightly increases, thereby increasing the steering ratio of rear wheels 50. Thus, the greater the weight of the user, the more body 20 flexes, and the greater the increase in the steering ratio of rear wheels 50. Increasing the steering ratio of rear wheels 50 reduces the angle through which body 20 must rotate about axis 25 in order to achieve a particular rear wheel 50 pivot angle. This may be particularly advantageous to heavier users who likely have larger feet; reduced rotation of body 20 about axis 25 to achieve the desired pivot of rear wheels 50 offers the potential to reduce the likelihood of the users heel or toes contacting the ground 11 while turning.
Discs 66a, 66b may be axially spaced apart sufficiently to be rotated relative to each other and relative to body 20 to achieve the desired angle θf by loosening or decoupling releasable attachment member 62 from body 20. Once discs 66a, 66b are aligned as desired, attachment member 62 may be re-coupled to body 20 and tightened to sufficiently hold discs 66a, 66b in place so that the desired angle θr is maintained during use of skateboard 10. Wedged discs 66a, 66b are preferably rigid to sufficiently maintain the desired angle θf. Moreover, the interfacing surfaces of discs 66a, 66b preferably comprise a high friction material or mating engagement mechanism (e.g., mating notches and recesses) that restrict the rotation of discs 66a, 66b relative to each other once aligned as desired and compressed into each other via attachment member 62.
In the manner previously described, the positioning of front wheels 30 and rear wheels 30 at the ends 20a, 20b, respectively, body 20 may be positioned such that height hb is less than axle heights hf, hr. The result is a lowered of body 20 of the skateboard 10, including a lower center of gravity while employing larger wheels which provide better ride, handling and stability. In conventional skateboards, the wheels are disposed directly under the skateboard deck, thus, larger wheels increase the height of the deck relative to the ground and thereby increase center of gravity and reducing the stability of the board.
In some embodiments, the skateboard (e.g., skateboard 10) may also include a brake or braking means to controllably reduce the speed of the skateboard. For example, a collapsible fender may be positioned at least partially about one of the rear wheels (e.g., rear wheels 50). By pushing down on such a brake, it engages the rear wheel about which it is disposed to generate a frictional braking force. The inner surface of the collapsible brake may also comprise an inner wheel that rotationally engages the rear wheel of the skateboard for frictional braking.
While preferred embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the system and apparatus are possible and are within the scope of the invention. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.
This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 60/977,919, filed Oct. 5, 2007, and entitled “Personal Transport Device,” which is hereby incorporated herein by reference in its entirety.
Number | Date | Country | |
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60977919 | Oct 2007 | US |