Motorcycle with a rear suspension having a pull shock track system

A motorcycle including a main frame, a rear swing frame, and a pull shock assembly operatively disposed between the main frame and the rear swing frame. The swing frame is pivotally mounted to the main frame. The main frame includes a pair of slide tracks that receive a slide member of the pull shock assembly. A link arm extends between a forward portion of the swing frame and the slide member, and translates pivotal movement of the swing frame into sliding longitudinal movement of the slide member. A damper associated with the slide member restricts sliding movement of the slide member and, thus, pivotal movement of the swing frame. The link has a forward end secured to the swing frame and a rearward end secured to the slide member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally directed toward motorcycle suspension systems and, more particularly, toward rear suspensions for motorcycles having a rear swing frame.

2. Description of Related Art

Motorcycles having a rear swing frame are known in the art. Moreover, suspension systems for motorcycles having rear swing frames are also known in the art. Such suspension systems typically include one or more shock absorbers that extend from a forward portion of the rear swing frame upwardly to a rear portion of the front or main frame. In these known systems, the shock absorber is typically aligned with the pivotal direction of the rear swing frame so as to dampen the pivotal movement of the rear swing frame.

Unfortunately, the conventional rear swing frame designs and, more particularly, rear swing frame suspensions, require a significant amount of open space. In some motorcycles, such space is simply not available. Further, the conventional swing frame suspensions present an appearance that may be undesirable. Therefore, there exists a need in the art for an improved rear suspension for a motorcycle having a rear swing frame that provides a low profile and is generally hidden in use.

SUMMARY OF THE INVENTION

The present invention is directed toward an improved rear suspension for a motorcycle having a rear swing frame wherein the suspension is generally hidden in use, has a low profile, and permits use in motorcycles wherein limited space is available.

In accordance with the present invention, a motorcycle includes a main frame, and a rear suspension assembly. The main frame has a forward end and a rearward end. A front wheel is secured to the main frame and defines a first rotational axis. The rear suspension assembly includes a rear swing frame and a shock assembly. The rear swing frame is pivotally secured to the main frame. The shock assembly is operable to dampen pivotal movement of the rear swing frame relative to the main frame.

In further accordance with the present invention, a rear wheel is secured to the rear swing frame and is vertically movable therewith. The rear wheel defines a second rotational axis. The rear swing frame is pivotally secured to the main frame at a location that is vertically above a line extending between the first and second rotational axes when the rear suspension assembly is at rest.

In further accordance with the present invention, the rear suspension assembly further includes a slide member and a damper. The slide member is slidably secured to the main frame while the damper is affixed to the slide member and to the main frame. The slide member is operatively associated with the rear swing frame so as to translate pivotal movement of the rear swing frame into: longitudinal movement of the slide member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Initially it is noted that the present invention is not directed toward the specific arrangement and relative position of various motorcycle components, but rather is directed toward an improved motorcycle frame and an improved rear suspension for a motorcycle having a rear swing frame. Accordingly, many conventional features of the present invention will only be illustrated herein schematically and will only be discussed hereinafter in a cursory fashion and only as necessary to explain the frame and suspension of the present invention.

If further information regarding other aspects of the motorcycle is desired that are not discussed at length herein, reference should be made to the commonly assigned copending U.S. patent applications Ser. No. 10/780,336, filed Feb. 17, 2004; Ser. No. 10/780,201 filed Feb. 17, 2004; and Ser. No. 10/877,536, filed Jun. 24, 2004, entitled MOTORCYCLE WITH IMPROVED THERMOSTAT MOUNTING, the disclosures of which are expressly incorporated herein in their entireties.

With reference toFIG. 1, a motorcycle10incorporating the improved rear suspension assembly12according to the present invention is illustrated in a somewhat schematic or simplified manner. The motorcycle10includes a front wheel14, a rear wheel16, an engine18, a front or main frame20, and a rear swing frame22. The rear suspension assembly12includes the swing frame22and a pull shock assembly24(FIG. 5), described hereinafter.

The front wheel14is mounted to the lower end of the front forks26that are pivotally secured to the steering head, which is affixed to the main frame20. The engine18is relatively forwardly disposed, and is mounted between upper and lower rails28,30of the main frame20. The rear wheel16is rotatably affixed to the rear end of the rear swing frame22, and rotatably driven by the engine18via a transmission and drive means, such as a drive belt, drive chain, or drive shaft, as is conventional.

With reference toFIGS. 2A,2B, and3, the front or main frame20includes a pair of upper rails28, a pair of lower rails30, and a pair of rear rails32. Each of the upper rails28have a forward portion28aand a rearward portion28b. Each of the lower rails30have an upper, forward end30aand a lower, rearward end30b. Each of the rear rails32have an upper end32aand a lower end32b.

More specifically, the lower rails30are somewhat L-shaped when viewed from the side, so as to define a first portion30a′ that extends downwardly from the lower rails' upper forward end30a, at which point the lower rails30are affixed to the upper rails28, and a second portion30b′ that integrally extends rearwardly from a lower end of the first portion30a′ and terminates in the pair of slide tracks30cat the lower rearward end30b, which will be discussed further hereinafter with regard toFIGS. 2C,2D, and4. Preferably, each of the slide tracks30creceives an elastomeric stop member33. The lower rails30preferably include at least one cross member30dthat extends between and interconnects the slide tracks30c.

The cross member30dhas a low profile so as to be positioned vertically below, and thereby not interfere with, the channels30c′ defined by slide tracks30c, as will be apparent from the following description.

The lower end32bof the rear rails32are joined to the lower rails30at a location that is just forward or ahead of the rearward end30bof the lower rails30such that the slide tracks30cextend rearwardly of the union of the rear rails32and the lower rails30. The lower rails30may include further cross members (not shown) that extend between and interconnect other portions of the lower rails30, such as the first portion30a′ of the lower rails30, so as to stiffen and unify the main frame.

The upper rails' forward portions28aare secured to the upper, forward ends30aof the lower rails30, as noted hereinbefore. The upper rails' rearward portions28bare secured to the upper end32aof the rear rails32. The upper rails' forward portions28aare generally parallel to the lower rails' second portions30b′, while the upper rails' rearward portion28bcurves downwardly from the upper rails' forward portion28a. Naturally, the forward and rearward portions28a,28bare affixed to one another, such as by welding.

The rear rails32are shaped somewhat like an inverted L when viewed from the side, and each include a forward arm32a′ that terminates in the upper end32a, which is connected to the rearward portion28bof the associated upper rail28, and a downward leg32b′ that includes the lower end32b, which is connected to the rearward end second portion30b′ of the corresponding lower rail30.

Each of the downward legs32b′ defines an opening32cthat receives a bearing or bushing34(e.g. a sleeve bearing) to which and through which a stub axle36extends, as described more fully hereinafter. A series of threaded bores32c′ surround the opening32cto permit the bearing/bushing34and/or the stub axle36to be affixed to the downward leg32b′.

The rear rails32also include forward and rearward cross members32d,32eto interconnect and unify the rear rails32. The forward cross member32dextends between the forward ends of the rear rails' forward arms32a′, whereas the rearward cross member32eextends between the rearward ends of the rear rails' forward arms32a′.

The rear swing frame22includes a pair of generally triangular plate-like forward portions38, a pair of rearward portions40, and an inner half fender42.

The forward portion38includes an upper end38a, a lower end38b, and defines an opening38cthat receives a bearing44. The bearing opening38cis surrounded by threaded openings38c′ that align with the threaded bores32c′ surrounding the opening32cin the downward leg32b′ of the rear rails32. Accordingly, threaded fasteners affix bearings/bushings34,44and/or the stub axles36, which extend through the aligned bushing/bearings34,44, while permitting the rear swing frame22to pivot about the stub axles36, as will be apparent from the following discussion.

In this regard it is noted that the pivotal connection is relatively forwardly disposed and, as such, the forward portions38of the swing frame22are disposed between the rear rails32of the main frame20. Accordingly, the pivotal connection defined by the stub axle36is forward of the slide tracks30c, as will be described more fully hereinafter. Naturally, the stub axle36may be in the form of a bolt and, as such, may have a nut threaded onto its inner or distal end. It is further noted that the pivotal connection between the main frame20and the swing frame22may be replaced by other known or hereafter developed structures without departing from the scope and spirit of the present invention. For example, the pivotal swing frame mounting structure taught in U.S. Pat. No. 4,556,119, the disclosure of which is expressly incorporated herein in its entirety, may be used herein.

Each of the rearward portions40each include an upper arm40aand a lower arm40b. A forward or proximal end40a′ of the upper arm40ais affixed to the upper end38aof the forward portion38while a forward or proximal end40b′ of the lower arm40bis affixed to the lower end38bof the swing frame forward portion38. The distal or rearward ends40a″,40b″ of the upper and lower arms40a,40bare integrally affixed to one another and cooperate to define a mount to which the rear wheel16is rotatably secured.

The inner half fender42extends between and unifies the interconnection of the upper arm40awith the forward portion38and the interconnection of the lower arm40band the forward portion38, as illustrated.

The pull shock assembly24is affixed to the main frame20and includes at least one and, preferably, a pair of shock absorbers or dampers48, a forward mounting bar50, a slide member52, and a pair of link arms54. The forward mounting bar50is affixed, preferably by welding, between the second portions30b′ of the lower rails30bof the main frame20, relatively ahead of the slide tracks30c. In this regard it is noted that the mounting bar50serves as a cross member linking the opposite sides of the main frame20.

The dampers48extend between and interconnect the stationary mounting bar50and the slidably movable slide member52. The dampers48are of a conventional construction, such as a cylindrical housing that receives a fluid and/or spring damped piston, and accordingly will not be discussed further hereinafter.

The slide member52has a body portion52ahaving slides or rollers52bextending from each end. Each of the slides or rollers52bis slidably received within an associated one of the channels30c′ of the slide tracks30c.

As illustrated, an annular narrowing is formed between the body portion52aand the rollers52bin which a rearward end54aof the link arms54is received. A forward end54bof the link arms54is pivotally received over the mounts38b″ provided at the forward lower end38b′ of the swing frame forward portion38, as will be described hereinafter. As will be appreciated, the link arms54have a solid body portion to which the forward and rearward ends54b,54aare secured, with the ends54a,54bincluding bearings so as to permit pivotal connection of the link arms54to both the slide member52and the swing frame22. As will be appreciated, the link arms54may have a static or non-adjustable length or, preferably, the length of the link arms54may be adjusted by threading the forward and rearward ends54a,54bof the link arms54into the solid body portion. It is further noted that, so long as the function is maintained, various link arms and link arm mounting schemes may be used in conjunction with the present invention without departing from the scope and spirit of the present invention.

When the main frame20, swing frame22, and pull shock assembly24are assembled, the swing frame22is pivotally secured to the main frame20via the stub axle36and cooperation of the bearings/bushings34,44. The forward portion38of the swing frame22fits between the downward legs of the32b′ of the rear rails32, and the mounts38b″ provided by the swing frame forward portion38are disposed forwardly or ahead of the slide tracks30cof the main frame lower rails30. The link arms54extend between and interconnect the pull shock assembly24to the swing frame22and are at a slight angle relative to horizontal, and are generally concealed from view by the lower rails30of the main frame20. More specifically, the link arms54connect the swing frame22to the slide member52, the rollers of which are is slidably received and movable within the slide tracks30c. Thus, the swing frame22, upon which the rear wheel16is rotatably mounted, is able to pivot relative to the main frame20in a controlled or damped fashion.

With reference toFIG. 2A, the motorcycle10incorporating the suspension of the present invention is schematically illustrated, with portion removed therefrom for clarity, and showing the suspension in an at rest or passive condition. As is shown, reference plane A—A extending along the length of the motorcycle10passes through the rotational axis of the front wheel and the rotational axis of the rear wheel16, when the suspension is in a passive or at-rest condition. As used in the description that follows, the reference plane A—A is stationary and substantially parallel to the ground and to the lower rails second end30b′, and will be used hereinafter to help define and describe motion of the rear swing frame22relative to the main frame20and related motion of the pull-shock assembly24.

It is further noted that the pivot axis of the swing frame22, which is defined by the stub axle36, is disposed relatively above the axis A—A when the suspension is passive (FIG. 2A) and also when the suspension is active (FIG. 2B). It is further noted that the swing frame pivot axis is disposed relatively forward and above the slide tracks30c, and that the link arms54are generally concealed by the second end30b′ of the lower rails30.

As the rear swing frame is pivoted upwardly from the passive condition (FIG. 2A) into an active condition, such as when the rear wheel goes over a bump (FIG. 2B), the rear wheel16moves upwardly (above the reference plane A—A) causing the rearward ends40a″,40b″ of the upper and lower arms40a,40bto move upwardly and thereby cause the rear swing frame22to pivot about the stub axle36. The lower forward end38b′ of the swing frame forward portion38moves downwardly and rearwardly, which drives the slide member52rearwardly in the slide tracks30ctoward the elastomeric stop member33due to the rigid connection between the forward portion38and the slide member52. The stop member33prevents the slides or rollers52bfrom engaging the end of the associated slide tracks30c.

Sliding movement of the slide member52causes the dampers48to extend, and thereby urge the slide member52and, thus, the rear swing frame22, back toward the at-rest position. As will be apparent to those skilled in the art, assuming that the passive condition for the slide member52is relatively mid-way along the length of the slide tracks30c(i.e., between about one-quarter and three-quarters of the available slide member travel), a substantially identical, albeit opposite in direction, sequence of motions will occur should the rear wheel16go into a hole.

The construction of the rear suspension assembly12and positioning of the pull shock assembly24of the present invention in the manner described and illustrated hereinbefore provide several advantages. For example, the rear suspension assembly12of the present invention does not occupy much space within the motorcycle, and frees a substantial amount of space between the upper and lower rails of the main frame20that can now be used for essential motorcycle components, such as the engine and radiator, which can now be positioned more freely than would be otherwise possible. The pull shock assembly24has, a low profile vertically and occupies little space, especially fore and aft space between the engine18and the rear tire16. Moreover, the pull shock assembly is substantially hidden from view, and affords a remarkably clean and appearance to the motorcycle.

Although the currently preferred embodiment of the present invention has been described herein with specificity, it is submitted that the present invention is not limited thereto, but rather is capable of numerous modifications, rearrangements and substitutions of parts without departing from the scope and spirit of the present invention, as embodied in the claims appended hereto. For example, it is considered clear that the front or main frame could be formed in numerous different ways without departing from the scope and spirit of the present invention. Moreover, the particular construction and arrangement of the pull shock assembly may be considered to exemplary in many ways. For example, while a pair of dampers is currently preferred, it is considered apparent that a single damper could be used in place of the pair of dampers that were described and illustrated herein. Further, the specific structure of the swing frame described herein is not to be interpreted in a limiting fashion. Rather, it is apparent that the swing frame can take on numerous appearances so long as the function of the swing frame described herein be retained. Finally, the particular manner of pivotally securing or mounting the swing frame to the main frame is not restrictive. Rather, those skilled in the art may devise any number of functionally equivalent methods to pivotally secure the swing frame to the main frame.