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US 2003/0196843 A1Published application
Motorcycle rear suspension swingarm assembly
AssigneeYamaha Hatsudoki Kabushiki Kaisha
InventorShidehiko Miyashiro
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AssigneeYamaha Hatsudoki Kabushiki Kaisha
InventorShidehiko Miyashiro
Estimating the term…
An off-road motorcycle incorporates a swingarm assembly for pivotally supporting a rear wheel relative to a frame of the motorcycle. Preferably, the swingarm includes right and left arms extending rearwardly from a forward connecting portion. Right and left rear wheel mount members are secured to the right and left arms, respectively, to rotatably support the rear wheel of the motorcycle. Preferably, the arms of the swingarm assembly are formed at least partially by a hydroforming process and the center of each of the arms has a width that is greater than the width of either a forward or rearward end of the arm. In addition, the forward end of each of the right end left arms preferably is bent inward such that the forward portion of the swingarm assembly is narrower than the rear portion of the swingarm assembly. The hydroforming process permits the inner wall of the arms to be vertical and substantially planar along the region where the arms are bent about a generally vertically extending axis. In addition, a vibration absorbing coating can be applied to the wheel support members in a manner to be interposed between an inner surface of the wheel support members and the outermost portion of a hub of the rear wheel.
An off-road motorcycle comprising a frame, a front suspension assembly rotatably supported by the frame and rotatably supporting a front wheel, a rear swingarm assembly pivotably supported by the frame and rotatably supporting a rear wheel, an internal combustion engine supported by the frame and being drivingly coupled to the rear wheel, the swingarm assembly comprising at least one hydroformed arm extending along a side of the rear wheel in a direction substantially aligned with a vertical, central plane of the motorcycle, the arm having an intermediate portion defining a first width in a direction substantially normal to the central plane, a forward end defining a second width and a rearward end defining a third width of the arm, the first width being greater than both of the second width and the third width.
An off-road motorcycle comprising a frame, a front suspension assembly rotatably supported by the frame and rotatably supporting a front wheel, a rear swingarm assembly pivotably supported by the frame and rotatably supporting a rear wheel, an internal combustion engine supported by the frame and being drivingly coupled to the rear wheel, the swingarm assembly comprising at least one elongated, tubular arm extending along a side of the rear wheel in a direction substantially aligned with a vertical, central plane of the motorcycle, the arm having an intermediate portion defining a first width in a direction substantially normal to the central plane, a forward end defining a second width and a rearward end defining a third width of the arm, the first width being greater than both of the second width and the third width.
A motorcycle comprising a frame, an engine mounted to the frame, a rear swingarm pivotally connected to the frame, a rear wheel supported by the swingarm and driven by the engine, the swingarm having an arm portion that is unitarily formed and that has an enlarged central portion relative to the ends, the arm portion being formed by providing an elongated tubular workpiece, providing a die having a first portion and a second portion, the first portion and second portion of the die cooperating to define a die cavity sized and shaped substantially identical to a desired final shape of an outer surface of the arm, placing the workpiece within the die cavity and closing the die, introducing a fluid into an internal space of the workpiece, and pressurizing the fluid to a sufficient level such that the workpiece conforms substantially to the size and shape of the die cavity.
A rear suspension swingarm assembly for an off-road motorcycle, the swingarm assembly configured to be pivotably supported by a frame of the motorcycle and rotatably supporting a rear wheel of the motorcycle, the swingarm assembly comprising a connecting portion defining a pivot axis of the swingarm assembly relative to the frame of the motorcycle, the swingarm assembly additionally comprising a first elongated, tubular arm and a second elongated, tubular arm, the first and second arms being fixed to the connecting portion and extending in a rearward direction therefrom, each of the first and second arms having an intermediate portion defining a first width, a forward end defining a second width and a rearward end defining a third width of the arms, the first width being greater than both of the second width and the third width.
Dependencies are inferred from the claim text.
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With pivoted chain-stay: for cycles without a pedal crank, e.g. motorcycles
Cycles
Term end not estimated
This application is related to, and claims priority from, Japanese Patent Application No. 2001-185805, filed on Jun. 20, 2001, the entirety of which is incorporated by reference herein.
1. Field of the Invention
This invention relates generally to vehicle suspension systems. More particularly, this invention relates to a rear suspension swingarm assembly for supporting a rear wheel of a motorcycle.
These and other features, aspects and advantages of the present invention will be described with reference to drawings of a preferred embodiment, which is intended to illustrate, and not to limit, the present invention. The drawings comprise 19 figures.
FIG. 1 is a side elevational view of an off-road motorcycle incorporating a preferred rear suspension swingarm assembly that is connected to a frame.
FIG. 2 is a top plan view of the rear suspension swingarm assembly of FIG. 1. The swingarm assembly includes a forward connecting portion, right and left arms extending rearwardly from the connecting portion and right and left wheel mount members fixed to rearward ends of the arms.
With reference to FIG. 1, an off-road motorcycle incorporating a preferred rear suspension swingarm assembly is identified generally by the reference numeral 20. The motorcycle 20 includes a frame assembly 22 that is formed primarily from tubular members, which may have circular or other suitable cross-sectional configurations.
frame assembly includes a head pipe 23. A front suspension fork assembly 24 is joumaled for rotation with respect to the frame assembly 22. In particular, the front suspension fork assembly extends through the head pipe 23 of the frame assembly 22. A handlebar assembly 26 is carried at an upper end of the front fork assembly 24 and can be used to steer a front wheel 28, which is rotatably journaled at a lower end of the fork assembly 24 in any suitable manner. The front fork assembly 24 also supports a front fender 30 at a position above the front wheel 28. The front fender 30 is arranged to deflect dirt, mud or other debris that may be thrown upward by the front wheel 28.
A lower, rearward portion of the frame assembly 22 pivotally supports a rear swingarm assembly 32. The swingarm 32 supports a rear wheel 36 of the motorcycle 20 at its rearward end. Preferably, the swingarm 32 is formed of aluminum or a similar alloy such that the overall weight of the swingarm can be reduced. In addition, as will be explained below, the swingarm 32 is designed to further reduce the overall weight of the swingarm.