Fiber reinforced tensile element

A tensile element connection, comprising first and second bracing elements and a tensile element having a first portion connected to the first bracing element and a second portion opposed to the first portion and connected to the second bracing element, and an applied tensile load along the tensile element. The tensile element includes a preformed rod that is comprised of reinforcement fibers in a matrix. At a temporarily elevated temperature greater than the service temperature, a localized region of the matrix is in a softened state of increased deformability such that a localized region of the rod is deformed under pressure to include a laterally outwardly projecting engagement surface. The tensile element is comprised of said rod with the engagement surface formed therein and is connected to one of the first and second bracing elements by means of an overlie engagement at the engagement surface to restrain the tension load.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a fiber reinforced longitudinal tensile element that includes an engagement surface for connection with a bracing element. The present invention is particularly related to the spoke of a vehicle wheel, where the bracing element comprises the rim or hub of the vehicle wheel.

(2) Description of the Related Art

Heretofore, the vast majority of bicycle wheels have been constructed using steel wire spokes with one headed end for connection with the bicycle hub and an opposing end that is directly threaded to accept a spoke nipple that engages the rim. By adjusting the threaded connection between the spoke and the nipple, the overall length of the spoke may be shortened or lengthened to create a balanced pretension in the spokes of the wheel.

Bicycle spokes serve as structural tensile elements where the tension of the spoke is resisted by the hoop compression of the outer rim hoop to create a remarkably efficient wheel structure for handling the loads associated with the operation of the bicycle. The technology of conventional bicycle spokes has remained unchanged for the better part of a century.

Cyclists are continually striving to reduce the weight and increase the efficiency of their bicycle, especially rotating components such as the bicycle wheel. However, the steel spokes of conventional bicycle wheels are quite heavy and add significant weight to the wheel assembly.

In addition to their excessive weight, steel bicycle spokes have poor vibration-damping characteristics and tend to be very efficient at transmitting road vibration to the rider. By transmitting vibration, rather than absorbing it, the conventional steel-spoke bicycle wheel lacks in rider comfort and control.

In attempt to reduce weight, many makers of high-end wheels have resorted to forming their spokes from thinner gage steel wire. This causes the stress in the spoke to increase and makes the wheel more prone to spoke failure due to fatigue. The thinner steel wire has lower tensile stiffness, which can contribute to a reduced side-to-side stiffness of the wheel.

In the last 30 years, great strides have been made in the development of very lightweight materials that also have excellent tensile characteristics. Some of the most attractive of these materials include high-strength fibers, such as carbon fiber, aramid fiber, liquid crystal fiber, PBO® fiber and the like. However, when attempting to utilize them as spokes in bicycle wheel construction, these fibrous materials are far more difficult to efficiently couple or terminate than their conventional steel-wire counterparts. In the few cases where these high strength spokes have successfully been utilized in bicycle wheels, their cost and complexity has been very great. This is the primary reason that the vast majority of bicycle wheels are still constructed using steel spokes.

While there have been some attempts to produce fiber reinforced spokes for bicycles, these spokes have been molded as a complete unit. In the case where thermoset matrix resins are utilized, this results in very long molding cycles because the fiber must be carefully layed up and the resin needs long residence time in the mold in order to catalyze and harden. Also, since the entire spoke is molded, the corresponding mold tool is very large and expensive. Further, since the cycle times are slow, a large number of these tools are required in order to achieve sufficient production throughput. Alternatively, in the case of molding a single thermoplastic spoke (such as U.S. Pat. No. 5,779,323), this is commonly achieved through injection molding, a fluid flow process that only accommodates short reinforcement fibers and not the continuous fibers as defined herein. These short fibers have far inferior tensile properties in comparison with continuous fibers.

Accordingly, it is an objective of the present invention to overcome the forgoing disadvantages and to provide a spoke and/or tensile element and a connection system for such spoke and/or tensile element that is strong, lightweight and inexpensive to produce.

It is a further object of the present invention to facilitate the utilization of high strength fiber-reinforced materials in spoke and/or tensile element construction and to create a high strength connecting system for such spokes and/or tensile elements.

It is a still further objective of the present invention to provide a connection system for spokes and/or tensile elements that has minimal mechanical complexity and is easily serviceable, and permits easy installation and removal of such spokes and/or tensile elements.

Further objects and advantages of the present invention will appear hereinbelow.

SUMMARY OF THE INVENTION

In accordance with the present invention, it has now been found that the forgoing objects and advantages may be readily obtained.

The present invention comprises a longitudinal tensile element such as a spoke, having an end portion, a longitudinal axis, and a cross-section thereof, a bracing element (as defined herein), and a tensile axis of applied tensile load along the span of the spoke. The spoke is connected to the bracing element. The spoke is advantageously made of fiber-reinforced material. The spoke includes a laterally outwardly projecting spoke engagement surface formed therein to provide an overlie engagement with the connector to support tensile load. The spoke preferably includes at least two longitudinally spaced spoke engagement interfaces resulting in a longitudinal engagement interface with the bracing element. The spoke may be directly connected to the bracing element or it may be connected to the bracing element by means of an intermediate connector, where the spoke is connected to the connector and the connector s connected to the bracing element.

A first aspect of the present invention relates to the spoke comprised of reinforcement fibers in matrix. The fibers may impart the majority of the tensile properties of the spoke, while the matrix serves to support and bind the fibers. One preferable matrix material consists of a thermoplastic polymer resin. Thermoplastic polymer may be heated and softened to a softened state with increased plasticity and pliability so that the material may be plastically deformed to a desired contour and then cooled to its original temperature so that this contour is “frozen” and integrated into the spoke. Another potential matrix material is a thermoset resin. Some thermoset resins, when carefully heated above its glass transition temperature, may be softened and plastically deformed to the desired contour in a manner similar to that described above for thermoplastic resins. Another potential matrix material is a metallic material, such as an aluminum or magnesium alloy, which may also be temporarily heated, softened, and plastically deformed in a manner similar to that described above for thermoplastic resin. As a general rule, the matrix has a lower softening temperature than the reinforcement fibers. It is preferred that the fiber strands remain unbroken or only minimally damaged during this forming process. By heating a localized region of the spoke rod, the matrix may be softened to increase its plasticity while the fiber remains undamaged. This temporary increase in plasticity may preferably permit the fibers to deflect somewhat as the matrix is deformed so that the fibers remain unbroken by this process. This is in contrast to a cold-forming process where the spoke rod is deformed at room temperature (i.e. the service temperature of the spoke) without increased plasticity, where the fibers are frozen within the matrix, and these fibers may be more easily fractured or damaged by such a forming process. This localized region corresponds to only a portion of the spoke rod, which is in contrast to heating the entire spoke rod.

In an advantageous embodiment, the reinforcement fibers are aligned to be parallel to the tensile axis. In a further advantageous arrangement, the fibers are at least 4 mm in length or are, more advantageously, continuous and generally extend the length of the spoke. In a further advantageous embodiment the fibers extend continuously to span between the engagement surface and the span portion. Such fiber-reinforced spokes may have very high tensile properties at a much lower weight than conventional steel or metallic spokes, thus providing a significant weight savings to the wheel assembly. The spoke(s) may be produced by drawing, extruding, pultruding, machining, molding, forging, casting, among many other fabrication processes well known in industry.

The spoke is initially pre-formed as a long slender rod of generally constant cross section along its length. One preferable method of producing this pre-formed rod is the pultrusion process, which has minimal waste and is very cost efficient and provides continuous fibers along the length of the rod. Through the temporary application of heat and pressure, a localized portion of the spoke rod is softened and plastically deformed to mold the spoke to provide a configured external surface therein to include a laterally projecting engagement surface. Subsequently, the spoke is cooled and solidified such that this engagement surface serves to provide an overlie engagement to connect the spoke to the bracing element. The overlie engagement provides a structural connection between the spoke and the bracing element to support spoke tension forces.

A second aspect of the present invention relates to the geometry of the engagement surface. The engagement surface may surround and circumscribe the cross section of the spoke about the longitudinal axis (as defined herein). The engagement surface may only partially circumscribe the cross section of the spoke. The engagement surface may be flat or may be angled or may be rounded or may have any other laterally projecting contour. The configured surface may include a singular engagement surface at a single longitudinal position or it may include a multiplicity of longitudinally spaced engagement surfaces at a multiplicity of longitudinal positions to provide a longitudinal engagement interface (as defined herein) for connection with the rim and/or hub. The engagement surface(s) provides an overlie engagement with the rim and/or hub and/or an intermediate connecting element to support and resist spoke tension forces. A longitudinal engagement interface may be preferable since the associated multiplicity of overlie engagements tend to distribute the contact stress over these multiple engagements.

A third aspect of the present invention relates to the connection between a connector and the spoke. The connector preferably includes a first portion and a second portion thereof, where the lateral distance between the first and second portions is reduced and/or contracted to retain the spoke to the connector and to maintain an overlie engagement between the spoke and at least one of the first and second portions. At least one of the first and second portions may include a cavity to receive the spoke. The first and second portions are most commonly laterally opposed to each other. The first and second portions may be two portions of a singular connector element. Alternatively, the connector may be a multi-piece connector composed of a multiplicity of discreet segments, where a first segment includes the first portion and the second segment includes the second portion. In addition to retaining the spoke, the lateral contraction between first and second portions may serve to laterally sandwich and clamp the spoke to maintain a lateral pressure between the spoke and the first and second portions. Preferably, this lateral pressure occurs along at least a portion of the longitudinal engagement to press the mating longitudinal engagement surfaces into intimate contact. The overlie engagement provides a structural connection between the spoke and the bracing element to support spoke tension forces.

A fourth aspect of the invention relates to the overlie engagement between a connector and the spoke. This overlie engagement is preferably a longitudinal engagement (as defined herein) between a longitudinal engagement surface of the spoke and the longitudinal engagement surface of at least one of the first and second portion of the connector. The longitudinal engagement may be utilized to provide a highly efficient structural connection between the spoke and the bracing element to support spoke tension forces.

The present invention obtains many advantages. One advantage of the present invention is the ability to utilize lightweight materials for the spoke while minimizing the cost and expense of the completed assembly.

Another advantage of the present invention involves the deformation in only a localized region of the spoke rod. This allows the spoke rod to me manufactured in a highly efficient and low cost manner, such as pultrusion. Deforming only a small localized region of the spoke rod requires only minimal heating energy and may be achieved quickly with a minimum of labor and tooling. The tooling is also smaller in size and correspondingly low in cost. This is in contrast to the alternative of deforming and/or molding the entire spoke as a single unit, which requires greater heating energy, greater cycle times, increased labor, and larger and costlier tooling.

The present invention may be readily adapted to lightweight fibrous spoke reinforcement fibers, such as carbon fiber, aramid fiber (such as Kevlar®), LCP (liquid crystal fiber such as Vectran®), PBO (polyphenylenebenzobisoxasole fiber such as Zylon®), polyethylene fiber (such as Spectra®) and the like. These fibers are impregnated within a matrix to create a spoke and/or tensile element that has a significant performance improvement over the steel spokes they commonly replace. In comparison with the steel wire commonly used in spoke construction, these fiber reinforced materials have equivalent or greater tensile strength than the steel spoke at a much lower density. This allows for the construction of a much lighter spoke and a lighter wheel. Further, these materials have significantly better vibration-damping characteristics than steel to reduce the vibration experienced by the rider and to provide greater rider comfort and control. Still further, these materials also have excellent tensile fatigue properties to reduce or even eliminate spoke failures due to fatigue.

The embodiments described herein are highly effective at transmitting tensile loads between the spoke and the bracing element and may be designed to provide a structural connection that is strong as or stronger than the spoke itself. The embodiments described herein are highly effective at producing a lightweight and high-performance vehicle wheel at an economical cost.

Further features of the present invention will become apparent from considering the drawings and ensuing description.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1describes the basic configuration of an exemplary prior art vehicle wheel, in particular, a bicycle wheel1, as well as a description of the direction conventions used throughout this disclosure. For clarity, the bicycle frame and the quick release skewer assembly are not shown in this figure. The hub shell14is rotatable about the axle9and includes at least two axially spaced hub flanges16aand16b, each of which include a means for connecting with the spokes2, with a hub body portion12therebetween. Axle9includes end faces11aand11bthat define the spacing of its mounting with the frame (not shown). The axial axis28is the axial centerline of rotation of the bicycle wheel1. The hub flange16may be contiguous with the hub shell14or it may be separately formed and assembled to the hub body12portion of the hub shell14. The spokes2are affixed to the hub flange16at their first end4and extend to attach the rim8at their second end6. The tire10is fitted to the outer periphery of the rim8. The wheel ofFIG. 1is generic and may be of tension-spoke or compression-spoke design.

The axial direction92is any direction parallel with the axial axis28. The radial direction93is a direction generally perpendicular to the axial direction92and extending generally from the axial axis28radially outwardly toward the rim8. The tangential direction94is a direction generally tangent to the rim at a given radius. The circumferential direction95is a cylindrical vector that wraps around the axial axis28at a given radius. A radial plane96is a plane perpendicular to the axial axis28that extends in a generally radial direction at a given axial intercept. An axial plane97is a plane that is generally parallel to the axial axis. An orientation that is radially inboard (or inward) is nearer to the axial axis28of rotation and a radially outboard (or outward) is further from the axial axis. An axially inboard (or inward) orientation is an orientation that is axially proximal to the axial midpoint between the two end faces11aand11b. Conversely, an axially outboard (or outward) orientation is an orientation that is axially distal to the axial midpoint between the two end faces11aand11b. A radially inboard orientation is an orientation that is radially proximal to the axial axis28and a radially outboard orientation is an orientation that is radially distal to the axial axis28. An axially inwardly facing surface is a surface that faces toward the axial midpoint between the two end faces11aand11b. Conversely, an axially outwardly facing surface is a surface that faces away from the axial midpoint between the two end faces11aand11b. While it is most common for the hub shell14to rotate about a fixed axle9, there are some cases where it is desirable to permit the axle9to be fixed with the wheel1such as the case where the wheel1is driven by the axle9.

For the purposes of using conventional terminology, the term “hub flange” is used herein to describe a region of the hub shell14to which the spokes2are joined. While the surface of the hub flange may be raised and flange-like in comparison to other surfaces of the hub shell14, this is not a requirement for the present invention and the hub flange16may alternatively be flush or recessed relative to other hub shell surfaces.

As is well known in the art, a wheel1may be of tension-spoke construction, where the central hub hangs in tension by the spokes from the rim portion directly above, or it may be of compression-spoke construction, where the hub is supported by compressing the spoke directly beneath it. Since the present invention may be directed toward bicycle wheels and since the tension-spoke wheel is generally a more efficient structure than compression-spoke wheel, most of the discussion herein is focused with an eye toward tension-spoke wheel construction. However, it is anticipated that most, if not all, of the embodiments of the present invention may be adapted or otherwise applied to compression-spoke wheel construction as well. For a tension-spoke wheel, it is preferable that the wheel includes at least two hub flanges that are axially spaced on either side of the rim or, more specifically, the spoke attachment points at the rim. Thus the spokes fixed to opposite hub flanges will converge as they extend to the rim as illustrated inFIG. 2b. Additionally, a tension-spoke wheel will usually be pretensioned during assembly to create a pretensioned structure of balanced spoke tension that allows the axle supporting loads to be distributed among several, if not all, of the spokes of the wheel. It is this ability to share the stresses among its spokes that helps to make the tension-spoke wheel the highly efficient structure that it is. For a compression-spoke wheel, it is often preferable to employ at least two axially spaced hub flanges, however, in the case where the spokes have sufficient bending stiffness to support the requisite lateral or side-to-side loads, only a single hub flange may be employed.

FIGS. 2a, 2band 2cdescribe the current technology in conventional bicycle wheels that most cyclists are familiar with. This prior art design includes a rim8, a hub shell14and a plurality of spokes2. The hub shell14is rotatable about the axle9and includes a pair of axially spaced hub flanges16. The wheel is assembled by first threading each individual spoke2through an axial hole17in the hub flange16until the j-bend19is hooked within the hole17. The spoke2is then pivoted to extend in a generally radial direction toward the rim8. The enlarged portion34or “head” of the spoke2prevents the spoke2from pulling through the hole17in the hub flange16. The second end6of each spoke2is then fixed to the rim8via spoke nipples21. Tightening the threaded engagement between the spoke nipple21and the spoke2serves to effectively shorten the length of the spoke2. Thus, as the nipples21are threadably tightened, the spokes are drawn up tight and a degree of pre-tension is induced in the spoke2. By selectively adjusting this threaded engagement, the spoke pre-tension may be adjusted to align the trueness of the rim8. The spoke pre-tension is resisted by circumferential compression of the rim8and it is this balance of forces that imparts efficient structural integrity to the bicycle wheel1. Also shown inFIG. 2bis bracing angle38between the radial centerline plane of the rim8and the tensile axis36of the spokes2. As this bracing angle38is increased, the lateral or side-to-side stiffness (i.e. stiffness in the axial direction27) of the wheel1is also increased.

FIG. 3ashows an exemplary bicycle wheel23that corresponds to some of the embodiments described herein, such as the embodiment ofFIGS. 14a-cand the embodiment ofFIGS. 15a-c.FIG. 3ais shown to provide a generic assembly to illustrate an arrangement wherein the present invention may be adapted to utilization in bicycle wheel construction. The bicycle wheel23includes spokes2, hub14, rim8, and tire10. The hub14includes hub flanges16aand16b(obscured) and axle9. The rim8includes geometry for mounting of a tire10and a multiplicity of spoke holes22in its spoke bed wall33, each to accept an individual connector24. It is noted that the rim8shown here is an exemplary representation of a bracing element that may serve as a rim or a hub flange and may take on a wide range of forms. The spokes2are constructed of fiber-reinforced material and are connected at their first end4to their associated hub flange16aand/or16b(obscured) and at their second end6to the rim8and have a span portion5therebetween.

To create a solid connection between the spoke2and the rim8, the second end6of each fiber reinforced spoke2is first connected to a corresponding connector24at an engagement interface25as described variously within the instant disclosure. The connector24may otherwise be utilized to laterally sandwich and engage the second end6of the spoke2by means of a laterally overlying engagement interface13between the connector24and the second end6in a manner similar or identical to one of the embodiments of the present invention. The connector24shown here includes a shank portion29, a head portion31, and a transition surface32therebetween as shown inFIG. 3b, which is a detail view of the embodiment described inFIG. 3aand which shows the rim8in cross-section. As shown inFIG. 3b, shank portion29extends through spoke hole22, with transition surface32serving as an engagement surface to bear against the radially outboard surface35of the spoke bed wall33in an overlie engagement, which provides blocking engagement to resist spoke tension30. It should be noted that, the transition surface32provides engagement geometry to engage the connector24to the bracing element (rim8).

The connector24ofFIGS. 3a-bis generally shown to serve as a termination to the spoke2as a means to connect or anchor the spoke2to a bracing element (i.e. rim8). Note that the span of spoke2is aligned in the direction of spoke tension30and along the tensile axis36, which extends through the longitudinal axis26of the spoke2.FIG. 3ashows that several spokes2of the wheel7may be terminated at the rim8in this manner. The connector24may alternatively be connected to the first end4of the spoke2for connection to the hub14. For simplicity in describing this embodiment, the connector24is shown here to connect the second end6to the rim8, with the understanding that such an embodiment may be easily adapted to alternatively connect the first end4to the hub flange16aor16b(obscured) as well.

It is understood thatFIGS. 3a-bcorresponds to a simplified arrangement for illustration purposes. Several of the embodiments of the present invention may be applied to this arrangement, as well as arrangements which include facility for creating and/or adjusting spoke pre-tension, as described inFIGS. 2a-c.

The present invention comprises a spoke, which may be considered as a longitudinal tensile element having an end portion and a cross-section thereof, a bracing element, and a tensile axis of applied tensile load along the longitudinal tensile element. The longitudinal tensile element is connected to the bracing element by means of an engagement at an engagement interface between the longitudinal tensile element and a connecting element. The connecting element may be an intermediate element (such as connector24) where the spoke2is connected to the connecting element24and the connecting element is connected to the bracing element8or the connecting element may be integral with the bracing element (as described inFIGS. 11a-eandFIG. 16, for example) where the spoke is directly connected to the bracing element, which also includes geometry to engage and mate with the spoke. In the embodiments shown herein, the longitudinal tensile element is a vehicle wheel spoke2, the hub flange16aand/or16bconstitutes a first bracing element and the outer rim8constitutes a second bracing element.

The spoke2is a generally long slender tensile element with a longitudinal length greater than its lateral width. The spoke2includes a longitudinal axis26through the center of the spoke2, along its length and generally parallel to its sidewalls. The longitudinal tensile element (i.e. spoke) includes external sidewall surface(s) that extend generally along its length. As such, the longitudinal axis26is generally parallel to the sidewall surface. The spoke2also has a tensile axis36of applied tensile load30that extends along the span portion5of the spoke2between its anchor points at the rim8and hub flange16aor16b. The tensile axis36is generally collinear to the longitudinal axis26, except where the spoke2is bent to deviate from the tensile axis36. For the purposes of definition, as relating to spokes and connections thereto, the term “longitudinal” herein refers to alignment along the longitudinal axis37. A longitudinally inboard (or inward) orientation refers to an orientation proximal the midpoint of the span portion5. Conversely, a longitudinally outboard (or outward) orientation refers to an orientation distal the midpoint of the span portion5. The term “lateral” refers to alignment in a direction generally perpendicular to the longitudinal axis37. A laterally inboard (or inward) orientation refers to an orientation proximal the longitudinal axis26(i.e. centerline of the spoke2). Conversely, a laterally outboard (or outward) orientation refers to an orientation laterally distal the longitudinal axis26. The term “longitudinal axis” is generally interchangeable with the term “tensile axis”, unless otherwise noted. When referring to a spoke, the term “cross section” refers to a virtual cross sectional cut perpendicular to the longitudinal axis26along63-63ofFIG. 3aand the term “circumferential” refers to a vector that wraps circumferentially about the longitudinal axis26.

Some examples of a longitudinal tensile element include the spoke of a vehicle wheel, a guy wire, a control cable, or a structural tendon component, among others. In most of the embodiments of the present invention, the longitudinal tensile element is capable of supporting tension, otherwise known as positive tensile loading, along its length. However, the tensile element may alternatively support compression, otherwise known as negative tensile loading, along its length, where the longitudinal tensile element provides columnar support between two bracing elements. The span portion of the spoke is considered as the portion of the spoke that is under tension and that extends between its anchor points and/or engagements at the bracing elements (i.e. hub and rim). A location outboard of the spoke span is a location along the tensile axis36and/or longitudinal axis26that is longitudinally beyond, outward, or external to the span portion.

The spoke has longitudinal external sidewall surface(s) that may be generally parallel to the longitudinal axis and an end face that is generally perpendicular to the sidewall surface. With a slender spoke, the sidewall tends to have far greater available surface area than its end face. Since an engagement interface of greater surface area tends to provide a more robust connection, it is often preferable to provide an engagement interface that extends longitudinally along the sidewall surface and preferably by a longitudinal length at least twice the cross sectional thickness of the spoke. This is in contrast to conventional spoke arrangements that focus these loads on a singular longitudinal point or region of contact, as with conventional prior art wheel assemblies.

A longitudinal engagement is defined herein as an engagement that includes a continuous longitudinal engagement interface or, as particularly described herein, a longitudinal engagement that includes at least two engagement interface locations that are longitudinally spaced along the longitudinal axis of the spoke. The engagement interface may include a multiplicity of individual overlie engagements between the spoke and a connecting element that are longitudinally spaced to support spoke tension loads between the spoke and the connecting element. For example, a longitudinal engagement may include a configured or knurled surface of the spoke comprised of a multiplicity of laterally projecting engagement surfaces that are longitudinally spaced to have a mating overlie engagement with a configured or knurled surface of the connecting element that is also comprised of a multiplicity of laterally projecting engagement surfaces to support spoke tension forces therebetween. It is preferred that, when viewed in a lateral direction, a plan view shows the engagement surface associated with these projections to extend generally circumferentially in a direction that crosses the longitudinal axis or, in other words, extends in a direction generally perpendicular to the direction of spoke tension load.

It is generally desirable that the longitudinal length of such a longitudinal engagement be greater than the cross-sectional thickness or width of the spoke to create an effective engagement. Obviously, increasing the longitudinal length of engagement and/or the number of longitudinally spaced engagement surfaces will increase the combined interface surface area and will therefore increase the load carrying capacity of the engagement interface and joinder between the connecting element and the spoke. It is preferable to have a longitudinal length of engagement at least twice the lateral thickness of the spoke.

The longitudinal engagement may be very effective at distributing the spoke tension load among a multiplicity of engagement interfaces, and thus reduce the contact stresses, at any single engagement interface. Since spokes made of reinforced polymer materials tend to have lower surface hardness than steel spokes, they may not be able to support very high contact stresses without deformation or damage. As such, the longitudinal engagement is particularly applicable to these fiber reinforced spokes since it distributes the load across a multiplicity of engagement interfaces. These fiber reinforced spokes are particularly advantageous, since these materials tend to have the desirable qualities of very high strength combined with light weight. However, heretofore these materials have been difficult to apply to conventional spoke connection systems that are generally focused on construction and connections that are based on spokes of metallic materials.

A configured surface is defined herein as a region of variable surface geometry that includes laterally outwardly projecting raised contour(s) and adjacent laterally inwardly recessed or relieved contour(s) (relative to the raised contour(s)) to include a laterally outwardly projecting engagement surface adjacent the transition between these raised and relieved contours. Some examples of configured surfaces include surfaces that are threaded, knurled, ribbed, headed, raised, indented, warped, bent, etc. The embodiments described herein disclose a variety of configured surfaces and corresponding longitudinally spaced engagement surfaces, such as a ribbed surface, a helical threaded surface, and others. The engagement surfaces may be individual discontinuous surfaces, such as the flanks of ridges198aand198bofFIGS. 5a-bor they may be continuous surfaces, such as the flanks of a continuous thread ridge241of the helical thread described inFIGS. 7a-b. Thread ridge241wraps continuously around the longitudinal axis26such that, when viewed in a lateral direction, the plan view shows the thread ridge241to cross the longitudinal axis26multiple times to effectively create a multiplicity of longitudinal spaced engagement surfaces. It is may be preferable that the engagement surface crosses the longitudinal axis26(rather than parallel to the longitudinal axis26) in this way since this orientation corresponds to a blocking overlie engagement interface to support and resist spoke tension30forces.

The longitudinal engagements described herein utilize a connecting element with a pre-formed configured surface that includes a series of longitudinally spaced engagement surfaces and a spoke with a pre-formed configured surface that includes a series of longitudinally spaced engagement surfaces. The longitudinal engagement surfaces of the connecting element and of the spoke are preferably nested and laterally pressed together, forcing these engagement surfaces into intimate contact and increasing the lateral overlying depth of the overlie engagement. These nested engagement surfaces create a series of laterally extending overlie engagements in a longitudinal engagement interface that serves to firmly connect the spoke to the connecting element and to support spoke tensile loads therebetween. Further, by pressing and forcing these engagement surfaces into intimate contact, a considerable level of friction may also be maintained between these surfaces, which further augments this connection and its ability to resist spoke tensile loads therebetween.

The configured surfaces of the bracing element (or a connector connected thereto) and the spoke, as described herein, are pre-formed configured surfaces where both configured surfaces and their corresponding engagement surfaces are pre-formed prior to their assembly and connection together. This is in contrast to U.S. Pat. No. 7,862,128, which describes a deformed longitudinal engagement, where only one of the configured surfaces is pre-formed while the opposing surface is deformed on contact with the pre-formed surface in a deformed engagement. The deformed engagement has several shortcomings in comparison with the present invention. Firstly, the deformed engagement requires that the pre-formed surface be significantly harder than the deformed surface in order to create this deformation. This requires materials with high hardness, such as steel or other metallic materials, that may be costly and are likely very heavy. Secondly, this deformation-upon-assembly may likely be less effective at creating a well-defined engagement surface in the surface being deformed. This may correspondingly reduce the tensile loads that may otherwise be carried. Thirdly, this deformation results in very high contact stresses in both the pre-formed surface and the deformed surface. The high contact stresses may weaken these components adjacent the deformation site. For example, this contact stress may create micro-fractures in one or both of these components, which may further reduce the tensile loads that may otherwise be carried.

By having both configured surfaces pre-formed prior to their longitudinal engagement therebetween, as described in the instant invention, the resulting connection therebetween may be lighter, more robust, and more economical than the arrangement of U.S. Pat. No. 7,862,128. Firstly, the longitudinal engagement may be achieved without requiring one or the other component to have especially high hardness. This may reduce weight and/or cost as compared to U.S. Pat. No. 7,862,128. Secondly, since the configured surfaces may both be formed off-line in a purpose-built and controlled process, the engagement surfaces may be exceptionally well defined and contoured, resulting in a very highly effective longitudinal engagement therebetween with greater tensile load-carrying capacity. Thirdly, since the configured surfaces do not have the exceptionally high contact stresses associated with deformation, these components may not be weakened or overstressed when they are pressed into connection.

While a conventional threadable engagement between an externally threaded rod and an internally threaded hole may be considered as a longitudinal engagement, there must necessarily be some internal clearances therebetween to permit these two components to be threadably assembled. As such, the mating threaded surfaces are not pressed into intimate contact. The present invention includes a lateral displacement of one or both of the mating configured surfaces to reduce clearances therebetween and preferably press and force these two surfaces into intimate contact. This reduced clearance serves to greatly increase the tensile load carrying capacity of this longitudinal connection. This also permits the use of softer material(s) and softer configured surface(s), such as fiber-reinforced resins (i.e. composites), in such a longitudinal connection. For example, while carbon fiber reinforced polymer has very high structural performance characteristics, it is also a relatively soft material, especially in comparison to most metals. By laterally pressing a configured longitudinal engagement surface of carbon fiber reinforced polymer into intimate contact with a mating configured longitudinal engagement surface, a highly effective connection therebetween may be achieved to carry sufficient tensile loads. In the absence of such a laterally pressed longitudinal engagement (i.e. a conventional threadable engagement with comparatively large clearances therebetween), the tensile load carrying capacity of the connection may be significantly lower.

In order to take advantage of the light weight and high strength of the high-performance fiber-reinforced materials mentioned hereinabove, it may be preferable to incorporate these material(s) in the spoke. These materials tend to be anisotropic and have greater strength along the direction of the fiber. Thus it may be preferable that these fibers are aligned to be parallel to the tensile axis. It is also preferable that these reinforcement fibers be encapsulated in a matrix. While short or discontinuous fibers often provide significant reinforcement to the matrix material, it is preferable that the fibers be as long as possible to provide the greatest overlap with adjacent fibers. The utilization of continuous fibers that extend generally along the length of the spoke provides the highest mechanical properties, especially when these fibers extend between the span portion and the configured surface of the spoke.

A spoke of high strength fibers in a resin matrix has numerous advantages in the present invention. Firstly, the resin matrix adheres the adjacent fibers to each other so that, through a joinder to the external surface of the spoke, the overmolded interface has a connection with all of the fibers of the spoke, which permits the fibers to work together for optimal tensile properties. Further, the resin matrix coats the outside of the pre-formed spoke, which creates an optimal surface for joinder with the connector at the engagement interface.

A bracing element is one that resists or braces against all or part of the load of a tensile element. In other words, in order for a tensile element to maintain its tension (or compression) and remain a generally static structure, it must have a resisting or bracing element to bear against. Thus, the tensile element is generally anchored to two bracing elements and the tensile element thereby serves to connect the two bracing elements to each other. In an example where the tensile element is generally held in tension, such as the spoke of a tension-spoke vehicle wheel, a first bracing element could be the hub flange and a second bracing element could be the outer rim hoop. Similarly, in the case where the tensile element is generally held in compression, such as the spoke of a compression-spoke vehicle wheel, the bracing element is that element which the tensile element is pushed against.

In the descriptions provided herein, the term “coupling” identifies an arrangement where a connector serves to provide a structural connection between two tensile elements (i.e. spokes), thus permitting tensile loads to be transmitted from one tensile element to another within the span. A coupling may be considered to provide a connection within the span portion of the spoke or to couple together two spoke portions. In contrast, the term “termination” or “anchor” identifies a connector that serves to provide a means to connect the tensile element (i.e. spoke) at the terminus of its span, either directly or indirectly, to a bracing element (i.e. the hub or rim), to which the tensile element is intended to be anchored.

FIGS. 3c-dshows a bicycle wheel168similar in most respects to the bicycle wheel7ofFIGS. 3a-b. However,FIG. 3cddescribe a representative arrangement where a coupling is utilized to connect two discreet portions of a spoke to each other. The connector24ofFIGS. 3a-bis eliminated in favor of coupling collar77and fastener78. The spokes2are connected at their first end4to the hub14, and adjacent their second end6, to coupling collar77. To create a firm connection between the spoke2and the rim8, the coupling collar77is also connected to a threaded fastener78. The threaded fastener78is threadably mated to a spoke nipple21to connect with the rim8in the conventional manner. Spoke nipple21is generally conventional and includes an enlarged head portion23. It may be seen that the coupling collar77serves as a coupling element to join together two tensile elements (i.e. the spoke2and the fastener78). The tire10is mounted to the rim8in the conventional manner.FIG. 3cshows that all of the spokes of the wheel80may be connected at the rim8in this manner. The coupling collar77and the fastener78may alternatively be connected to the first end4of the spoke2for connection to the hub14. In such a case, the fastener78may be connected to the hub14via spoke nipples21or it may be directly threaded into mating holes of the hub flange16aor16b. Such an arrangement where the spoke2is threadably connected directly to the hub flange16is well known in industry.

FIG. 3dis a detail of the embodiment described inFIG. 3cand shows the rim8in cross-section. The spoke nipple21is fitted through hole28in the rim8and is retained in place by the head portion23in the conventional manner. The nipple21is of conventional configuration and includes a female threaded central bore that is mated to the male threaded fastener78. Thus, spoke pretension may be adjusted for each individual spoke by threadably tightening the nipple21on the fastener78, effectively shortening the spoke2to induce tension to the spoke2. Note that the span of spoke2is aligned in the direction of spoke tension load30, including a tensile axis36that is aligned in the direction of spoke tension30and extends through the longitudinal axis26of the spoke2. The coupling collar77serves as a coupling to connect a first tensile element (i.e. spoke2) to a second tensile element (i.e. fastener78), where the second tensile element is connected to a bracing element (i.e. rim8). The coupling collar77is connected to the fastener78and/or the spoke2by means of an overlie engagement interface similar or identical to the broad range of connecting arrangements described herein.

FIGS. 4a-d, 5a-b, 6a-b, 7a-b, 8a-c, 9a-d, and10a-cdescribe a variety of embodiments where a spoke rod is locally formed to include a configured surface. All except the embodiment ofFIG. 9a-gand 10a-cdescribe the configured surface as including longitudinal engagement surfaces as defined hereinabove. The spokes of these figures may be made from a wide variety of materials, and are preferably made of composite material, preferably a fiber-reinforced composite material that includes reinforcement fibers in a matrix as described hereinabove. These fibers are preferably continuous fibers, as continuous fibers that extend the full length of the spoke and which tend to afford the highest specific tensile strength. These fibers may be selected from a wide range of reinforcement fiber types well known in industry, including carbon fibers, among others. The matrix may be a metallic material or it may be a polymer resin material such as a thermoplastic or a thermoset resin or it may be another matrix material. It may also be advantageous that the external surface of the spoke include a coating, such as a resin-rich polymer coating to provide protection for the fibers and/or to provide an easily-formable surface for forming the configured surface as described. Since this coating is preferably unitary and/or solidly adhered and integral with the matrix resin, for the purposes of definition herein, such a coating may be considered to be an extension or a portion of the matrix resin.

FIGS. 4a-bdescribe a spoke170with reinforcement fibers172with an end portion174that has configured surfaces176aand176bin the form of a wavy and bent configuration. Spoke170is shown here to have a generally flat profile with a width178along faces179aand179bgreater than its thickness180(between faces179aand179b). It may be preferable that this width178be at least 1.6 times this thickness180for optimal aerodynamics and for greater width of configured surfaces176aand176b. The end portion174is formed to create a bent and corrugated configured surface consisting of a series of longitudinally spaced kinks or waves, where the cross sectional thickness180remains generally unchanged. Thus, end portion174includes a series of laterally outwardly projecting peaks181longitudinally adjacent a corresponding series of laterally relieved valleys182. The configured surfaces176aand176bcorrespond to a bent or wavy contour such that the longitudinally spaced peaks181of face179aare longitudinally coincident with valleys182of face179band vice versa. This wavy profile results in a series of laterally extending and longitudinally spaced engagement surfaces184aassociated with face179aand similar engagement surfaces184bassociated with face179b. Engagement surfaces184aand184bextend laterally outwardly and laterally opposed to each other and also extend along the width178and perpendicular to the longitudinal axis and the direction of spoke tension30forces. The bent configured surfaces result in engagement surfaces184aand184bthat are longitudinally staggered as shown.

FIG. 4cshows a spoke rod171prior to being formed to create spoke170, including a mold die set186consisting of upper plate187awith upper cavity188aand lower plate187bwith lower cavity188b. As is conventional in mold configuration, upper cavity188aand lower cavity188bhave a negative contour corresponding to the positive contour of the subsequently-formed configured surfaces176aand176brespectively. Upper cavity188aand lower cavity188bare preferably rigid surfaces as is conventional. Prior to molding and forming, the spoke rod171is shown as a generally straight longitudinal rod of generally constant cross section along the longitudinal axis26, with a straight and smooth external surface including end portion174and a longitudinal axis26. The spoke rod171is also preferably a generally rigid element that can support its own weight without slumping. The unformed end portion174of spoke rod171is positioned between upper cavity188aand lower cavity188bas shown inFIG. 4c.FIG. 4dshows the upper plate187aand lower plate187bas next pressed together in directions189aand189bto sandwich and plastically deform the end portion174to create the configured surfaces176aand176bas shown. Upon subsequent removal from the mold die set186, the spoke rod171has been deformed to include configured surfaces176aand176band is thus transformed to create the spoke170as shown inFIGS. 4a-b. It is noted that, due to the bent and corrugated end portion174, the overall longitudinal length of the spoke171may be slightly shorter than the original spoke rod170.

Spoke rod171is preferably made of carbon fiber reinforced polymer resin. Particularly if this resin is a thermoplastic polymer resin, then the end portion174may be heated before or during molding/forming to locally achieve a softened state of the resin at end portion174. The resin now has increased plasticity and is more highly pliable and deformable so that it may be molded and formed to conform to the contours of cavities188aand188bto create configured surfaces176aand176b. The fibers commonly will not also be softened, but will preferably instead be deflected to follow the contours of the now-deformed end portion174. Alternatively, the spoke rod171may have a thick coating such that the fiber reinforcement is positioned deep within a central core of the spoke rod171. In such a case, this coating, which may be the same material as the matrix, may be locally deformed without appreciably deflecting the fibers.

The matrix resin (and/or coating resin) is then cooled to its original temperature, preferably while still under the pressure provided by cavities188aand188b, to allow the resin to re-solidify to maintain the rigid configured surfaces176aand176b. If the resin is a thermoset polymer resin (such as epoxy), then the resin may be allowed to further catalyze to solidify the configured surfaces176aand176b, preferably while still under pressure provided by cavities188aand188b, to allow the resin to solidify to include rigid configured surfaces176aand176b. Alternatively or additionally, the thermoset resin may be locally softened by heating the region to be formed, especially if the spoke rod171is heated above the glass transition temperature of the thermoset resin.

For example, where the resin may preferably be a thermoplastic polymer resin, end portion174shown inFIG. 4cmay be first heated by some external means such as infra-red radiation. Then, when the mold die set186is closed, as shown inFIG. 4d, the cooler mold cavities188aand188bwill quickly form, chill, and solidify the end portion174to then include configured surfaces176aand176brigidly formed therein. In an alternative example, the mold cavities188aand188bmay be heated so that their forming surfaces may transfer heat to end portion such that it may soften upon contact therebetween to simultaneously plastically deform and create configured surfaces176aand176b. In a further alternative example, the upper mold cavity188amay be in an energized ultrasonic horn where mechanical energy may be transferred from the horn to the end portion174to simultaneously heat and plastically deform the end portion174to create configured surfaces176aand176b. End portion174is subsequently or simultaneously cooled to its original temperature and re-solidified to include a rigid and stable configured surfaces176aand176b.FIGS. 4c-ddescribe only one representative method of molding and forming a given configured surface in the spoke. A wide range of alternate methods and/or molding configurations known in industry may alternatively be utilized to create this configured surface.

It is understood that the service temperature of the spoke170is below the softening temperature of the resin so that the geometry of the configured surfaces176aand176bare returned to its original harder and rigid state upon subsequent cooling so that that configured surfaces176aand176bare maintained during use. Since mold cavities188aand188bimpinge and apply pressure to the end portion174in a lateral direction, it may be considered that they serve to provide lateral deformation of the spoke170.FIGS. 4cand 4ddescribe a representative method of molding and deforming the spoke rod171in a specified localized region (i.e. end portion174) of an otherwise non-deformed spoke rod171. Due to this lateral deformation, the overall longitudinal length of the spoke rod171need not be appreciably altered when the end portion174is molded and formed to create spoke170. This localized region may alternatively be at location longitudinally inboard of the end portion174(as described inFIG. 8c).

It is noted that configured surfaces176aand176bare considered to be laterally outwardly facing external configured surfaces since they are formed in the exposed exterior side wall surface of the spoke170. This is in contrast to a laterally inwardly facing internal configured surface such as a configured surface that would be within an internal cavity of the spoke. An external configured surface may serve to engage a connecting element positioned laterally outwardly of the spoke.

FIGS. 5a-bdescribe a spoke190with reinforcement fibers192and with an end portion194that has configured surfaces196aand196bin the form of a ribbed or ridged configuration. Spoke190is shown here to have a generally flat profile with a width197along faces199aand199bgreater than its thickness200(between faces199aand199b). The end portion194is formed in a manner such as that described inFIGS. 4c-dto create configured surfaces196aand196bwith a ribbed profile consisting of a series of longitudinally spaced ribs or ridges198aand198bthat extend along the width197as shown. Spoke190starts as a generally smooth and straight rod of width197and thickness200. End portion194is then be locally formed in a method similar to that described inFIGS. 4c-d, or by some other method known in industry, to provide the configured surfaces196aand196bas shown here.

In contrast to the generally constant thickness180of the wavy configured surface176ofFIGS. 4a-b, the ribbed profile ofFIGS. 5a-bhas a variable thickness in the end portion194, with a greater thickness200′ across the peaks201of laterally opposed ridges198aand198band reduced thickness200″ across the laterally opposed valleys202between adjacent peaks201. Thus, configured surfaces196aand196bincludes a series of respective laterally projecting peaks201that are laterally opposed to each other. The configured surfaces196aand196bare shown here to be arranged such that the longitudinally spaced peaks201of configured surface196aare generally longitudinally coincident with the longitudinally spaced peaks201of configured surface196b, while longitudinally spaced valleys202of configured surface196aare generally longitudinally coincident with the longitudinally spaced valleys202of configured surface196b. The flanks of ridges198aand198bmay serve as laterally projecting engagement surfaces to create an overlie engagement for connection with a bracing element (not shown) to support spoke tension forces. Similar to that described inFIGS. 4a-b, the ribbed profile ofFIGS. 5a-bresults in a series of longitudinally spaced engagement surfaces associated with configured surfaces196aand196b. These engagement surfaces extend along the width197and perpendicular to the longitudinal axis26and to the direction of spoke tension30forces. Configured surfaces196aand196bmay be formed in end portion194in a manner similar to that described inFIGS. 4a-dor in any other forming method known in industry, preferably a method that utilizes heat and pressure locally applied to the end portion194.

FIGS. 6a-bdescribe a spoke210similar to the spoke190ofFIGS. 5a-b, however spoke210includes only one configured surface216. Spoke210includes reinforcement fibers212with an end portion214that has a configured surface216in the form of a ribbed configuration. Spoke210is shown here to have a generally flat profile with a width218along faces219aand219bgreater than its thickness220(between faces219aand219b). The end portion214is formed to create a single configured surface216with a ribbed profile consisting of a series of longitudinally spaced ribs or ridges224that extend along the width218as shown. Spoke210starts as a generally smooth and straight rod of width218and thickness220. End portion214may then be locally formed in a manner similar to that described inFIGS. 4c-dor by some other method known in industry, to provide the configured surface216as shown here.

Since the spoke210has only one configured surface216formed in face219a, the surface223is generally smooth and non-configured in the region laterally opposed to configured surface216. The ribbed profile ofFIGS. 6a-bhas a variable thickness220in the end portion214, with a greater thickness220′ at the peak of the ridge and reduced thickness220″ in the valley between adjacent peaks. Thus, end portion214includes a series of laterally projecting peaks221longitudinally adjacent a corresponding series of laterally relieved valleys222. The flanks of ridges224may serve as laterally projecting engagement surfaces to create an overlie engagement for connection with a bracing element (not shown) to support spoke tension forces. Similar to that described inFIGS. 4a-b, the ribbed profile ofFIGS. 6a-bresults in a series of longitudinally spaced engagement surfaces associated with configured surface216. These engagement surfaces extend along the width218and perpendicular to the direction of spoke tension30forces. Configured surface216may be formed in end portion214in a manner similar to that described inFIGS. 4a-d.

FIGS. 7a-bdescribe a spoke230with reinforcement fibers232with an end portion234that has a configured surface236in the form of a helical ribbed or externally threaded configuration. Spoke230is shown here to have a generally circular cylindrical profile with a circular cross section of diameter240. Spoke230starts as a generally smooth and straight rod of diameter240. End portion234may then be locally formed in a manner similar to that described inFIGS. 4c-dor otherwise formed to provide a configured surface236shown here as an external thread238consisting of a helical ribbed thread profile shown here. This helically ribbed profile consists of a laterally continuous raised helical thread ridge241that wraps around the longitudinal axis26to create series of longitudinally spaced ribs or ridges that extend to cross the longitudinal axis26when viewed in a plan view as shown inFIG. 7b. The helically ribbed profile is shown here as a conventional “vee” profile where the flanks of ridge241are tapered with angle239between root and crest. While this helical thread ridge241is technically a single ridge that wraps around the diameter of end portion234to double back on itself, as viewed in the plan view ofFIG. 7b, this ridge241creates a series of longitudinally spaced ribs to provide a longitudinal engagement surface to be utilized in providing a connection between the spoke230and a bracing element.

The helical ribbed profile ofFIGS. 7a-bhas a variable thickness in the end portion234, with a major diameter243at the laterally outward peak (corresponding to the major diameter of the thread) of the thread ridge241and minor diameter245at the root242(corresponding to the minor diameter of the thread) between longitudinally adjacent peaks. Similar to that described inFIGS. 4a-b, when viewed as shown inFIG. 7b, the helical ribbed profile ofFIGS. 7a-bresults in a series of longitudinally spaced engagement surfaces (corresponding to the laterally projecting flank of the thread ridge241) associated with configured surface236. These engagement surfaces extend to cross the longitudinal axis26to provide a mechanical overlie engagement to support spoke tension30forces. The thread ridge241may provide an overlie engagement with a mating internal thread of a connecting element (not shown) in a threadable engagement to support and resist spoke tension30loads. An example of such an engagement is shown inFIGS. 14a-eand 15a-e. While the helical thread ridge241is shown here to be a continuous helical ridge, it is envisioned that the helical thread ridge241may alternatively be a discontinuous or otherwise interrupted helical ridge.

As shown inFIGS. 8a-b, spoke45includes an end portion50with a configured surface in the form of ribbed or knurled surface40, which includes a series of laterally raised ribs41that are longitudinally spaced along the longitudinal axis26to create correspondingly laterally relieved portions44therebetween along the longitudinal axis26. The transition between ribs41and relieved portions44results in a series of longitudinally spaced laterally outwardly projecting engagement surfaces (i.e. flanks) therebetween. The flanks are shown here to be tapered with angle70between root and crest. These lateral projecting surfaces may be utilized to provide interlocking and overlying engagement with a bracing element as a means of connection therebetween to support and resist spoke tension30forces. Examples of such an arrangement are described variously herein. Spoke45starts as a generally smooth and straight rod with a circular cross section of diameter61. End portion50may then be locally formed in a manner similar to that described inFIGS. 4c-dor by some other means known in industry to provide the knurled surface40as shown here. Spoke45is shown here to be generally round in cross-section and ribs41are circular ribs that create a major diameter47of knurled portion, with relieved portions44resulting in a minor diameter49of knurled portion. Spoke45is shown to be a fiber-reinforced spoke45, with high strength fibers51in a resin matrix as described hereinabove.

WhileFIGS. 8a-bdescribe a spoke45with a knurled surface40adjacent its end portion, the knurled surface40may alternatively be located in a middle region or mid portion75of the spoke, as shown inFIG. 8c.FIG. 8cdescribes a spoke72that includes a knurled or configured portion74located at a midpoint along the spoke72, as opposed to the end portion50of spoke45as described inFIGS. 8a-b. Spoke45starts as a generally smooth and straight rod of diameter71. Mid portion75may then be locally formed in a manner similar to that described inFIGS. 4a-dor otherwise formed to provide the configured portion74as shown here. In bicycle wheel applications, it may be preferable that mid portion75be located at least 100 millimeters from the end portion of the spoke72.

Spoke72is shown to be a fiber-reinforced spoke72, with high strength fibers73in a resin matrix, as described hereinabove. The configured surface74is shown here to be identical to knurled surface40ofFIGS. 8a-b. By locating the configured surface74at a midpoint along the length of the spoke72, a duplex spoke72may be created, which incorporates two structural spans76aand76b, with each span extending between two bracing elements. For example, the configured portion74may be engaged to the hub flange (not shown), with a first span76aextending to anchor at one point of the outer rim (not shown) and a second span76bextending to anchor at another point of the outer rim.FIG. 8cprovides one example of a duplex spoke arrangement, which may alternatively take on a variety of forms, including alternate contours substituted for the configured portion74as well as alternate spoke profiles.

FIGS. 9a-ddescribe an embodiment where an enlarged portion or head140is formed directly onto the second end126of a spoke rod121to create a spoke122. It is preferable that the spoke rod121of this embodiment be of the type with continuous fibers141encapsulated in a thermoplastic polymer resin matrix. Spoke rod121shown here starts as a generally smooth and straight rod having a constant circular cross section of diameter123along its longitudinal axis26. Spoke rod121may alternatively have a non-circular cross section profile. As is preferred, spoke rod121is shown here to be a generally rigid rod that may extend within cavity145without slumping or leaning. End portion126is then locally formed as shown or otherwise formed to provide the enlarged portion140of spoke122as shown here.

FIGS. 9a-bshow how such a spoke122may be created to include an enlarged portion140. Prior to being formed, spoke rod121is clamped in a mold144with the end portion126extending into the mold cavity145of mold144as shown inFIG. 9a. The end portion126of spoke rod121is locally heated from its original state to a softened state of reduced hardness and increased plasticity. While end portion is in this softened state, ram146is displaced and pressed in direction147to plastically deform the end portion126to conform to the mold cavity145as shown inFIG. 9band to form an enlarged portion140directly onto the end portion126. Mold144and ram146may be considered as two portions of a forming die set to deform the end portion126. Note that this is merely a representative method of forming such an enlarged portion140in a predetermined localized region of a spoke rod121. Since ram146presses to deform the spoke122in a longitudinal direction, it may be considered that ram146serves to provide longitudinal deformation of the spoke122. Alternatively, a wide range of alternate forming techniques may be utilized that are known in industry. For example, ram146may be replaced by an ultrasonic horn, where ultrasonic energy is used to heat, soften, and plastically deform the second end5of spoke2. Due to this longitudinal deformation, the overall longitudinal length of the spoke rod121is likely shortened somewhat when the end portion126is molded and formed to create enlarged portion140.

After deformation, the spoke122is cooled to its original state and removed from the mold144. The result is that an enlarged portion140is now rigidly formed on the second end126of spoke122to include a flared shoulder148as illustrated inFIG. 9c. The flared shoulder148may be considered as a configured surface and as a laterally outwardly projecting engagement surface of the spoke122. The un-deformed portion of the spoke122is now considered to be a shank portion124. It should be noted that the fibers141of spoke122may preferably extend within the enlarged portion140to create uninterrupted structural connection between the spoke122and enlarged portion140. The enlarged portion140has a larger diameter142than the diameter123of shank portion124, thus enlarged portion140may be considered to be a region of variable cross section geometry along the longitudinal axis26. The laterally projecting flared shoulder148is shown here to be tapered at angle149to create a tapered engagement surface that circumferentially circumscribes the shank portion124. It is noted that the tapered shoulder148may be preferable to a square shoulder because this corresponds to a less-sharp and more gentle bend to the fibers141as they extend between the shank portion124and the enlarged portion140. Reducing the sharpness of the this bend tends to increase the increase the strength and tensile properties of the fibers141in this bent region.

FIG. 9dshows an exemplary representation of how the spoke122may be connected to a bracing element. Threaded collar134may be utilized as an intermediate connecting element to connect the spoke122to a spoke bed135of a bracing element (i.e. hub flange or rim). Threaded collar134includes external threads131, hole132to receive the shank portion124, tapered step139to engage with flared shoulder148, and flats138for manual manipulation with a wrench (not shown). Shank portion124extends through hole132and the flared shoulder148of the enlarged portion140is matched to step139of the threaded collar134to create a laterally overlying engagement interface143to support and resist spoke tension30forces. Spoke bed135includes a threaded hole137therethrough, with the external threads131of threaded collar134threadably engaged thereto. By utilizing a wrench (not shown) on flats138, the threaded collar134may be rotated about the tensile axis36to adjust the threaded engagement between the threads131and the threaded hole137to adjust the pre-tension of the spoke122in a manner similar to that described inFIGS. 2a-c. In contrast to the spokes described inFIGS. 4a-d, 5a-b, 6a-b, 7a-b, and 8a-b, which all show a multiplicity of longitudinally spaced engagement surfaces, flared shoulder is shown here to provide a singular engagement surface. The engagement interface143is shown here as a tapered interface such that spoke tension30will tend to wedge the flared shoulder148against the step139.

FIGS. 10a-cdescribe an embodiment similar to that ofFIGS. 9a-d, with an enlarged head154formed directly onto the end portion151of the spoke150. It is preferable that the spoke150of this embodiment be of the type with continuous fibers152encapsulated in a thermoplastic polymer resin matrix. As shown inFIG. 10a, the head154may be formed in the end portion151in a manner similar to that described inFIGS. 9a-bto include a flared shoulder156and a recess158with tapered sides160. Spoke150also includes a recess158with a tapered surface in its end portion150. Plug162includes tapered surface164that is matched to tapered sides164of recess158.

Spoke150had started as a generally smooth and straight rod of diameter127. Enlarged head154was then locally formed, using a variety of possible processes described herein and/or otherwise known in industry, to provide the flared shoulder156(i.e. configured surface) as shown here. The flared shoulder156may be considered as a laterally outwardly projecting engagement surface of the spoke150. In contrast to the solid enlarged portion140of embodiment ofFIGS. 9a-d, where the enlarged portion140has a larger cross-sectional area than the remainder of the spoke122, the head154, with recess158, preferably spreads the fibers152as shown to maintain a generally constant cross-sectional area along the longitudinal axis26. It should be noted that the fibers152of spoke150are shown here to preferably extend within the head154to create an uninterrupted structural connection between the spoke150and the head154. As shown inFIG. 10a, a plug162, with tapered surface164is positioned to be assembled to the recess158of spoke150.

As shown inFIGS. 10b-c, the plug162is assembled to the recess158in direction161such that tapered surface164is nested with the tapered sides160of recess158. The plug162may be joined to the recess158by means of a variety of methods, including bonding, welding, mechanical fastening, etc. A solid enlarged head is thus created in the end portion151to create a headed spoke similar to that described inFIGS. 9a-d. The plug162serves to fill the recess158and to create a lateral bridge across tapered sides160to prevent the flared shoulder156from collapsing when the spoke150is subject to spoke tension30forces, such as described inFIG. 9d.

FIGS. 11a-ddescribe an embodiment that includes a clamping member86to sandwich and clamp the spoke45between the hub flange85and the clamping member86. As shown inFIGS. 11a-b, hub shell84includes a hub flange85and a bearing bore89to facilitate mounting of a bearing (not shown) and axle (not shown). Hub flange85serves as both a bracing element and a connecting element and includes internally threaded holes46and configured cavities43with associated knurled surfaces90in its face42for engagement with configured or knurled surfaces40of spokes45. Spokes45are identical to those described inFIGS. 8a-b. Clamping member86includes clearance holes100to receive screws87and configured cavities88with associated knurled surfaces91in its corresponding face37that are aligned to be opposed to cavities43of the hub flange85. Cavities43and88have configured surfaces (i.e. knurled surfaces90and91respectively) to provide a recessed contour that is matched to the knurled surface40of the spoke2. Knurled surfaces90and91are shown here as a series of longitudinally spaced internal ribs that extend laterally inwardly and are arranged to mate and engage with the corresponding ribs41and relieved portions44of spoke45. Screws87are shown here as representative fasteners that may be utilized to assemble the clamping member86to the hub shell84to sandwich the spokes45.

Knurled surfaces90,91, and40had been pre-formed prior to this assembly. Upon assembly as shown inFIGS. 11b-c, spokes90are first positioned such that knurled surfaces40are nested in their corresponding cavities43, with the knurled surfaces40nested with corresponding knurled surfaces90. Clamping member86is then assembled to the hub shell84in direction98, as shown inFIG. 3c, to axially sandwich the knurled portions40of spokes2, with the knurled surfaces40now also nested with corresponding knurled surfaces91. Screws87are passed through clearance holes100and threadably engaged with mating threaded holes46of the hub flange84. When the screws87are threadably tightened into holes46, with the underside of the screw heads pressed against the clamping member86, the clamping member86is driven axially toward the hub flange85, in direction98, to provide clamping force48to sandwich and clamp the knurled portions40of spokes45. The knurled surfaces40are thus nested and pressed between cavities88and43such that the external ribs of knurled surface40are laterally overlapping, overlying, and thus are longitudinally engaged, to the internal ribs of knurled surface90at engagement interface101and to the internal ribs of knurled surface91at engagement interface102. With knurled surfaces40intimately engaged and interlocked with knurled surfaces90and91, a firm longitudinal engagement connection between the hub shell84and the spoke45is thus achieved. The spokes45are now structurally anchored to the hub flange85and are capable of resisting spoke tension30forces. The clamping member86is firmly engaged and retained to the hub flange84by the screws87, which also serve to maintain their clamped connection with the spokes45. Since the clamping member86and hub flange85both have a longitudinal engagement at engagement interfaces101and102(with the spoke45) to restrain spoke tension30loads, both clamping member86and hub flange85are also considered to be connectors or connecting elements. It is noted that clamping member86and hub flange85are two components of a single connecting element assembly and that are laterally displaced toward each other to create engagement interfaces101and102that serve to anchor a multiplicity of spokes45. Screws87serve to laterally retain and lock clamping member86and hub flange85to maintain engagement interfaces101and102.

In this embodiment, a wide range of materials may be utilized to form the hub flange85, clamping member86, and spoke45. The spoke is preferably made of fiber reinforced polymeric composite material or a metallic material, such as aluminum, titanium, or steel. The hub flange85and clamping member86may be made of a wide range of materials that are preferably light weight and high in strength and stiffness, such as aluminum, magnesium, and/or fiber reinforced polymer. For example, the hub flange85and/or clamping member86may be made of polyamide resin reinforced with glass or carbon fibers that are known to possess high structural strength and may be easily and economically molded in conventional processes.

Note that the lateral depth99aof cavity88and the lateral depth99bof cavity43may be controlled such that, upon tightening of the screws87, faces42and37contact each other, thereby providing a hard depth-stop to limit the lateral depth of overlie engagement between the knurled surface40and knurled surfaces90and91at engagement interfaces101and102. The spoke45is longitudinally retained to the hub flange85by the laterally projecting overlie engagements at the engagement interfaces101and102between the knurled surface40and respective knurled surfaces90and91to resist spoke tension30forces.

In the arrangement shown inFIG. 11d, faces37and42axially abut each other such that knurled surfaces90and91may have a loose fit or only lightly contact knurled surface40in a positional engagement. Since faces37and42bottom out against each other in what is termed a “hard stop”, this abutting interface provides the axial depth stop for the lateral overlie engagement between knurled surface40and knurled surfaces90and91to limit any lateral preload from clamping force48.

Alternatively, as shown inFIG. 11e, the axial depths99aand99bmay be designed to be somewhat shallower than that shown inFIG. 11d, such that the axially abutting knurled surfaces40,90, and91abut and stack against each other to limit the travel of the clamping member86in direction98, leaving a small axial and lateral gap103between faces37and42as shown inFIG. 11e. In other words, the knurled surface40provides a lateral depth stop between knurled surfaces90and91. As such, further tightening of the screws87(beyond initial contact between the knurled surface40and the cavities88and43) will continue to provide further lateral clamping force48to further press and laterally preload the knurled surface40into intimate contact with knurled surfaces90and91at engagement interfaces101and102. Further, since ribs41taper laterally outwardly as shown, and the knurled surfaces90and91are matched to the ribs41, this lateral clamping and preload results in a lateral wedging between knurled surface40and knurled surfaces90and91, to force these contours to be more closely matched such that spoke tension30load is more evenly distributed among the individual engagements of the longitudinal engagement therebetween. This serves to fortify and further increase the ability of the engagement interfaces101and102to restrain spoke tension30forces.

Whether the faces37and42bottom out against each other as shown inFIGS. 11a-dor the axial preload (with gap103) ofFIG. 11eis utilized, it may be preferable to maintain a lateral preload at engagement interfaces101and102. This lateral preload is defined herein as a residual laterally inward clamping force to squeeze, clamp, or otherwise maintain lateral contact pressure between the spoke (i.e. knurled surface40) and the connecting element (i.e. cavities88and43) at the engagement interfaces101and102. In addition to the retained overlie engagement at the engagement interfaces101and102, this clamping force serves to force the knurled surfaces90and91to laterally press and squeeze knurled surface40to laterally distort these knurled surfaces very slightly to become more solidly nested and more closely matched to each other to maximize the overlie engagement between these surfaces and to further resist spoke tension30forces. This also serves to add a significant normal force (i.e. lateral force) at the engagement interfaces101and102, which results in a high degree of friction therebetween to still further resist spoke tension30forces. InFIGS. 11a-d, the lateral dimensions of knurled surface40and depths99aand99bmust be very closely controlled to maintain this laterally inward clamping force. SinceFIG. 11eincludes gap103, the axial travel between cavities88and43is not self-limited, and the tolerances of these lateral dimensions need not be quite so precise to maintain this laterally inward clamping force. As such, the gap103ofFIG. 11emay be preferable over the hard stop ofFIGS. 11a-d.

The cavities88and43help to provide a well-defined location for alignment of the spoke45during its assembly with the clamping member86and hub flange85. Further, these cavities88and43provide a surface that partially circumferentially wraps around the surface of the spoke to provide more closely matched engagement interfaces101and102with the knurled surface40. This may be a preferable arrangement to aid in this assembly. Screws87, utilized to create the clamping force, are able to be disassembled and re-assembled from the hub flange85. As such, the entire clamped assembly may be may be easily disassembled and re-assembled, allowing the wheel to be serviced or the spoke(s)45to be replaced. Disassembly is performed by reversing the assembly process described above.

It should also be noted that, while screws87are shown here to provide the requisite connecting means to sandwich the spoke45between the hub flange85and the clamping member86, this is merely a representative connecting means and alternate connecting means are envisioned. For example, the assembly may be designed such that the hub flange85and clamping member86are first pressed by an external force and then retained in that pressed position by an alternate retaining means, such as a retaining clip or a retaining sleeve. Still further, a wide range of other alternate connecting and/or clamping means may alternatively be utilized.

The embodiment ofFIG. 12is similar to the embodiments ofFIGS. 11a-e. However, while the spoke45ofFIGS. 11a-chas two axially opposed engagement interfaces101and102, the spoke52ofFIG. 12utilizes only a single engagement interface53. Also, whileFIGS. 11a-eshow a multiplicity of spokes45connected to the hub flange85by means of a single clamping member86, the embodiment ofFIG. 12shows each individual spoke52as being clamped and/or retained to the hub flange69by a corresponding individual screw62.

Spoke52is of generally flat cross section, with a first end59having a smooth edge portion55laterally opposed to a configured edge portion54comprised of a series of directionally raked sawtooth profile ribs57pre-formed therein. Screw62includes threaded shank60, clamp surface65and head64. Hub shell68includes flange69, with a series of slots or open cavities56, each having a pre-formed configured surface66in the form of raked sawtooth ribs configured to provide a matched engagement with configured edge portion54. Hub flange69also includes a series of internally threaded holes58adjacent their respective cavities56to threadably mate with the threaded shanks60of screws62.

During assembly, spoke52is first positioned in cavity56such that the configured edge portion54is contacting the configured surface66such that ribs57are nested and matched with the mating ribs of the configured surface66. Screw62is then threadably engaged with threaded hole58and tightened such that the clamping surface65(i.e. underside of the head64) bears laterally against the smooth edge55of spoke2. As the screw62is further threadably tightened, clamping surface65presses the configured edge portion54into intimate engagement with the configured surface66, thus creating an interlocking longitudinal engagement therebetween at the engagement interface53between the ribs57and the configured surface66. This longitudinal engagement is laterally retained by the screw62, which preferably also provides a lateral preload and clamping force in direction67to actively press the ribs57into intimate nested engagement against the ribs of configured surface66. The spoke52is now firmly anchored to the hub flange69and is capable of resisting spoke tension30forces. The sawtooth rib57profile of the configured portion54is a preferable profile because this profile provides good blocking engagement with the mating ribs of the configured surface66to resist spoke tension30force, while maintaining good strength in the mating ribs. It is noted that hub flange69is a single connecting element that serves to anchor a multiplicity of spokes52. Screws62serve to laterally retain and lock spokes52to the hub flange69to maintain engagement interface53.

The embodiment ofFIGS. 13a-dis similar in many respects to the embodiment ofFIGS. 11a-ein that that two laterally opposed connecting elements are utilized to laterally sandwich the spoke and provide two corresponding longitudinal engagements with the spoke. While the embodiment ofFIGS. 11a-euses the screws87as a means to retain the clamping member130to the hub flange85, the embodiment ofFIGS. 13a-duses a retaining sleeve252to hold the gripping collars254aand254bin their longitudinally engaged and gripped position with the spoke45. Further, while the embodiment ofFIGS. 11a-cprovides attachment of a multiplicity of spokes within a single clamped connection between two elements (the clamping member86and the hub flange85), the embodiment ofFIGS. 13a-dprovides a connection and engagement interface with only a single mating spoke45.

FIG. 13ashows the components in exploded view prior to assembly. Sleeve252is a generally cylindrical element with an internal cavity256. Gripping collar254aincludes an external surface257aand a generally semi-circular cavity258athat is lined with configured surface260acomprised of a series of longitudinally spaced ribs as shown and as described hereinabove. Similarly, gripping collar254balso includes an external surface257band a cavity258bthat is lined with configured surface260bcomprised of a series of longitudinally spaced ribs as described hereinabove. These ribs are comprised of a series of laterally raised and relieved surfaces that are longitudinally spaced and that are pre-formed therein. Cavities258aand258bare similar to cavities43and88ofFIGS. 11a-e. Configured surfaces260aand260bprovide a matched contour to knurled surface40. Gripping collars254aand254balso include respective engagement surfaces259aand259b. The bracing element266represents a portion of the rim or hub flange (not shown) and includes a hole268therein to receive the spoke45. Spoke45is identical to that described inFIGS. 8a-b.

FIG. 13bdescribes the first step in the assembly process. Collars254aand254bare assembled in their respective directions262aand262bto sandwich the spoke45as shown. This causes the configured surfaces260aand260bof their respective cavities258aand258bto nest, interlock, and sandwich the ribs41of the knurled surface40of the spoke45. Next, as shown inFIG. 13c, sleeve252is assembled in direction264, with internal cavity256closely fitted to longitudinally overlap the external surfaces257aand257b. With sleeve252now in place surrounding and enclosing the collars254aand254b, as shown inFIGS. 13c-d, the internal cavity256laterally restrains the gripping collars254aand254b, holding them in their laterally engaged position to provide and maintain a longitudinal engagement interfaces263aand263bbetween the knurled surface40and the configured surfaces260aand260b. The gripping collars254aand254bare thus engaged and connected to the spoke45to support spoke tension30forces. Thus, the sleeve252may be viewed as a retaining element to maintain the longitudinal engagement and connection between the collars254aand254band the spoke45. As shown inFIG. 13d, engagement surfaces259aand259bhave an abutting overlie engagement with the bracing element266to bear against the bracing element266such that the spoke45is now firmly anchored to the bracing element266to resist spoke tension30forces. Gripping collars254aand254bmay be considered as intermediate connecting elements, as the spoke45is connected to the collars254aand254band the collars254aand254bare connected to the bracing element266. It is noted that gripping collars254aand254bare two components of a single connecting element assembly and that are laterally displaced toward each other to create longitudinal engagement interfaces263aand263bthat serve to anchor a single spoke45. Retaining sleeve252serves to laterally retain and lock gripping collars254aand254bto maintain engagement interfaces263aand263b.

As shown inFIGS. 14a-b, connector386includes a shank portion387with external dimension389and an enlarged head portion388with a transition surface390therebetween. Transition surface390may provide a laterally projecting engagement surface for subsequent engagement with a bracing element (not shown) in a manner similar to transition surface32shown inFIG. 3b. Connector386also includes a blind cylindrical cavity or hole392with an internal configured surface shown here as a series of longitudinally-spaced internal ribs394with an inside or minor diameter395. Internal ribs394are shown to provide configured geometry that extends laterally inwardly from the sidewalls of hole392and are pre-formed therein prior to any subsequent crimping of the connector386.

Spoke400is similar to spoke45ofFIGS. 8a-b. Spoke400is shown here to be generally round in cross-section and includes longitudinal axis26and end portion399with an external configured surface shown here as external ribs384with an outside or major diameter393, which is sized to have a clearance fit with the minor diameter395of internal ribs394. Spoke400preferably includes reinforcement fibers398as described herein. External ribs384are shown to provide geometry that projects and extends laterally outwardly relative to the spoke400and are pre-formed prior to any subsequent crimping of the connector386. As shown inFIG. 14a, the end portion399is first aligned with hole392. External ribs384and internal ribs394are both pre-formed configured surfaces that include laterally projecting geometry. For the purposes of definition herein, the term “pre-formed” refers to geometry that is formed prior to assembly or pre-assembly of the spoke400to the connector386.

Next, as shown inFIGS. 14band 14c, the end portion399of spoke400is inserted into hole392in direction391and positioned such that the connector386overlaps the spoke400along the longitudinal axis26to create a loose pre-assembly between the spoke400and the connector386, with lateral clearance between the external ribs384and internal ribs394. The blind hole392may serve as a depth-stop for the insertion of the spoke400and to conveniently control the longitudinal overlap therebetween.

Next, as shown inFIGS. 14dand 14e, the connector386is crimped onto the spoke400with external crimp force396applied to the shank portion387of the connector386to cause this portion of the connector386to plastically deform, shrink, and pinch to a reduced external dimension389′. This deformation of the shank portion387causes the hole392to shrink in direction383such that the internal ribs394are shrunk into nested interlocking engagement with external ribs384. The former lateral clearance between the external ribs384and internal ribs394is now reduced and preferably eliminated, with a squeezing and gripping lateral preload therebetween such that external ribs384are tightly nested and pressed against internal ribs394. Thus, external ribs384now have a laterally extending overlie engagement with the internal ribs394at the engagement interface397to create a longitudinal engagement therebetween and to securely join the connector386to the spoke400and to resist spoke tension30loads.

As seen inFIG. 14e, the crimp force serves to flatten and distort the cross section of both the spoke400and the connector386such that laterally opposed portions of the internal ribs394have exceptionally high depth of interlocking engagement with the external ribs384to improve the structural connection therebetween. Also, the crimped distortion of the shank portion387serves to correspondingly distort the cross section of the end portion399, resulting in a rotationally keyed engagement therebetween about the longitudinal axis26. The connector386may then be connected to the rim8as described inFIGS. 3a-bor may alternatively be connected to the hub (not shown, but known in industry). It is noted that connector386serves as a singular connecting element that is plastically deformed to laterally displace two portions toward each other to create engagement interface397that serves to anchor an individual spoke400. This plastic deformation serves to laterally retain and lock these two portions in this shrinked orientation to maintain engagement interface397.

While the configured surfaces of end portion399and hole392are shown to be external ribs384and internal ribs394respectively, a wide range of alternate configured surface geometries may be employed to create an interlocking overlie engagement therebetween. In a desirable alternate example, helical external threads may be substituted for external ribs384and helical internal threads may be substituted for internal ribs394. It is preferable that the thread pitch of external threads and internal threads be matched to each other. Prior to crimping, and corresponding to the assembly sequence described inFIGS. 14b-c, there may be lateral clearance between the major diameter of external threads and the minor diameter of internal threads to permit easy insertion and pre-assembly of the spoke with the connector. After crimping, and corresponding to the assembly sequence described inFIGS. 14d-e, this lateral clearance would be reduced, or preferably eliminated, such that these two configured surfaces are pressed together with a lateral preload to insure the maximum interlocking overlie engagement therebetween.

While a clearance fit between internal ribs394and external ribs384may permit easy pre-assembly between the spoke400and the connector386as shown inFIG. 14b, the resultant lateral clearance therebetween requires a relatively high degree of crimped shrinkage of the hole392in direction383. In an alternative arrangement, the hole392may be originally sized to have an interference fit with the end portion399of the spoke400. The end portion399may then be forcibly inserted into hole392, with the crimp force396serving to cinch and tighten the fit between the hole392and the end portion399.

It is noted thatFIGS. 11a-e,12, and13a-eshow a connecting element made of two discreet elements that are displaced toward each other to retain and create an overlie engagement with the mating spoke. In contrast,FIGS. 14a-eand 15a-eutilize a one-piece connecting element that is deformed such that one portion of the connecting element is displaced toward an opposing portion of the connecting element to retain and create an overlie engagement with the mating spoke. This deformation may be plastic deformation such that the connecting element retains the deformed configuration without elastically returning to its original non-deformed configuration.

The embodiment ofFIGS. 15a-chas similarity to the embodiment ofFIGS. 14a-ein that both the spoke230and the connector286utilize preformed configured surfaces to create a resultant longitudinal engagement. As shown inFIG. 15a, connector286includes a shank portion287having external dimension289and an enlarged head portion288with a transition surface290therebetween. Transition surface290serves to provide a generally laterally projecting engagement surface for subsequent engagement with a bracing element (not shown) in a manner similar to transition surface32ofFIG. 3b. Transition surface290is shown to be a circular surface that circumscribes the longitudinal axis26in an arrangement similar to a conventional spoke nipple. Connector286also includes a longitudinal hole292therethrough with an internal configured surface shown here as helical internal threads294with a minor diameter295. The flanks of internal threads294may be considered as continuous helical engagement surfaces that extend laterally inwardly from the hole292and that are pre-formed therein prior to subsequent crimped deformation.

Spoke230is generally identical to that described inFIGS. 7a-band is shown here to be generally round in cross-section. Spoke230preferably includes reinforcement fibers232as described herein. Major diameter243of external threads238is sized to be somewhat larger the minor diameter295of internal threads294, as is common in a threadable engagement. The thread flanks of external threads238may be considered as continuous helical engagement surfaces that extend laterally outwardly from the spoke230and that are pre-formed therein prior to subsequent crimping of the connector286. As shown inFIG. 15a, the end portion234is first aligned with hole292.

Spoke230is also shown to be a fiber-reinforced spoke230, with high strength fibers232in a resin matrix. For highest structural performance, it is preferable that these fibers232be generally continuous fibers that extend the full length of the spoke230. These fibers may be selected from a wide range of reinforcement fiber types well known in industry, including carbon fibers, among others. The matrix may be a metallic material or it may be a polymer resin material such as a thermoplastic or a thermoset resin. It may also be advantageous that the external surface of the spoke230include a coating, such as a resin-rich polymer coating to provide protection for the fibers and/or to provide an easily-formable surface to create external threads238.

Next, as shown inFIGS. 15band 15c, the end portion234of spoke230is threadably preassembled with hole292in direction301and resulting direction291such that external threads238are loosely threadably engaged with internal threads294and the end portion234longitudinally overlaps the hole292. Flanks of external threads284are laterally overlapping the flanks of internal threads294in a threadable overlie engagement to create a loose pre-assembly between the spoke230and the connector286. As is common in threadable assemblies, there is preferably a slight lateral clearance between external threads238and internal threads294to allow for this threadable assembly.

Next, as shown inFIGS. 15dand 15e, the connector286is crimped onto the spoke230with external crimp force296applied to the shank portion287of the connector286to cause this portion of the connector286to plastically deform, shrink, flatten, and pinch down to a reduced external dimension289′. This deformation of the shank portion287causes the hole292to correspondingly shrink in direction298and laterally pinch the end portion234such that the internal threads294are pressed into tightly nested and interlocking longitudinal engagement with external threads238at engagement interface297. The former lateral clearance between the external threads238and internal threads294is now reduced and preferably eliminated, with a squeezing and gripping laterally preloaded interface therebetween such that external threads238are tightly nested and laterally pressed against internal threads294.

The thread forms of internal threads294and external threads238are shown here as matched V-shaped thread forms such that, upon crimping, the mating thread flanks may tightly wedge against each other to create a high level of friction therebetween so that this threadable engagement is now a binding engagement to rotationally bind and lock the spoke230to the connector286about the longitudinal axis26, also restricting relative rotation between the connector286and the spoke230. Further, this crimped engagement causes external threads238to more deeply engage the internal threads294, taking up any internal clearance therebetween such that internal threads294fully support the external threads238(and vice versa) so that the thread flanks have less tendency to flex and squirm under applied spoke tensile force30, and such that this threadable engagement may support even greater tensile load. This lateral preloaded engagement is particularly effective when the spoke230is made of a softer and/or more flexible material, such as fiber reinforced polymer, and the connector286is made of a harder and/or stiffer material, such as aluminum or other metallic material. In such a case, the harder aluminum internal threads294effectively support the softer external threads238such that these external threads238maintain their optimal thread form under the application of spoke tension30force. Further, this binding engagement results in a deeper lateral overlie engagement between mating thread flanks, to further augment this longitudinal engagement and to support yet greater spoke tension30force. The result is a highly effective longitudinal threadable engagement between the spoke230and the connector286to support spoke tension30forces that is especially effective with spokes made of fiber reinforced composites. The connector286may then be connected to the rim8as described inFIGS. 3a-bor may alternatively be connected to the hub.

While the connector286may be made of a wide range of ductile materials, it may be preferable that the connector286be made of a lightweight metallic material such as aluminum or magnesium alloys, to minimize weight. The spoke230may be made of a wide range of materials known in industry. However, it is noted that fiber-reinforced composite material has particularly excellent properties to fit the requirements of spoke construction, including light weight and high strength. Heretofore, such fiber-reinforced spokes have proven to be difficult to terminate. However, the present invention is well suited to create terminations and/or couplings for use with fiber-reinforced spokes.

While the embodiments ofFIGS. 11a-candFIG. 12show how a connecting element may be integral with the hub flange, the embodiment ofFIG. 16illustrates that a connecting member may alternatively be integral with the outer rim hoop351as well. Rim hoop351is shown in radial cross section and is of generally conventional “double-wall” configuration, however it also includes a radially inwardly extending tab portion352. Tab portion352includes internally threaded holes354and a knurled or configured surface356pre-formed therein that includes a series of pre-formed longitudinally spaced ribs357that extend perpendicular to the longitudinal axis26. Clamping member360includes clamping surface364and clearance holes362that are aligned with threaded holes354. Spoke210is identical to that described inFIGS. 6a-band is of slightly flattened cross section as shown, with its end portion214positioned between knurled face356and clamping member360and with the configured surface216facing knurled face356as shown. Screw62includes threaded portion60and head64.

Upon assembly, the threaded portions60of the two screws62are first passed through their respective clearance holes362and then threadably assembled within their respective threaded holes354. Threadably tightening screws62serves to laterally clamp and sandwich the end portion214between the tab portion352and the clamping member360, with the ridges224of configured surface216nested and engaged with the ribs357of configured surface356and with clamping surface364bearing against surface223. The spoke210is thus sandwiched between configured surface356and clamping surface364. By threadably tightening the screws62, the clamping member360is pressed toward the tab portion352to provide a lateral preload to squeeze and grip the spoke210between clamping surface356and knurled face356to create a laterally overlapping longitudinal overlie engagement between the ribs357and the ridges224that are nested and interlocked therebetween. This longitudinal engagement serves to firmly connect the spoke210to the rim hoop351to support spoke tension30loads.

The embodiment ofFIGS. 17a-cis similar in many respects to the embodiment ofFIGS. 13a-din that two laterally opposed connecting elements are utilized to laterally sandwich the spoke to provide two corresponding longitudinal engagements with the spoke. While the embodiment ofFIGS. 13a-duses a sleeve252as a hoop to laterally bind the collars254aand254btogether to maintain the longitudinal engagement with the spoke45, the embodiment ofFIGS. 17a-cutilize a spoke bed308with an integral collar310that has tapered internal sidewalls312aand312bto laterally wedge the corresponding wedges314aand314blaterally toward each other to maintain their longitudinal engagement with the spoke45.

FIG. 17ashows the components in exploded view prior to assembly. Spoke45is identical to the spoke45described inFIGS. 8a-b. Spoke bed308represents the portion of a bracing element to which the spoke45is connected and includes an integral collar310with an opening311therethrough having ramped or tapered internal sidewalls312aand312blaterally opposed to each other as shown. Wedges314aand314bserve as connecting elements and include ramped sides316aand316brespectively and respective configured reliefs318aand318blaterally opposed thereto. Configured reliefs318aand318bare each configured to include a series of longitudinally spaced internal ribs319aand319bthat are pre-formed therein similar to configured surfaces260aand260bdescribed inFIGS. 13a-d. The configured reliefs318aand318bare matched to the ribs41of the knurled surface40of the spoke45.

FIG. 17bshows the wedges314aand314bas first pre-assembled to the end portion50of spoke45in respective directions320aand320bsuch that the ribs319aand319bare each nested to laterally overlap with the ribs41of knurled surface40. Ribs319aand319band41may be considered to provide engagement surfaces that result in an interlocking overlie engagement between the wedges314aand314band the spoke45. Ramped sides316aand316bhave respective wedging angles321aand321bthat are preferably matched to the wedge angles322aand322bof internal sidewalls312aand312brespectively.

Next, as shown inFIG. 17c, this preassembly is assembled to the collar310in direction322until ramped sides316aand316bcontact respective internal sidewalls312aand312b. Further displacement in direction322forces ramped sides316aand316bto wedge against internal sidewalls312aand312b, thereby serving to further laterally press wedges314aand314btoward each other and also to laterally press the configured reliefs318aand318bagainst knurled surface40, resulting in an overlying longitudinal engagement between ribs41and the ribs319aand319bat corresponding engagement interfaces321aand321bto support spoke tension30forces. This longitudinal engagement is considered as a self-energizing longitudinal engagement in that, as the spoke tension30load is increased, the wedging action between the internal sidewalls312aand312band ramped sides316aand316bfurther presses the wedges314aand314bin respective directions323aand323bto also further laterally preload and fortify their respective longitudinal engagements with the spoke45.

FIGS. 18a-cdescribe an arrangement where two spokes may be engaged to each other in a longitudinal engagement and also provide an example of a coupling arrangement. Spokes210are identical to that described inFIGS. 6a-b. Also included is sleeve330with a longitudinally extending opening334therethrough, having a width332and a height333, which corresponds to the width218of spokes210, as shown inFIG. 18a.

FIG. 18bshows the two spokes210assembled to each other in direction336so that their configured surfaces216are longitudinally overlapping in overlap region341and laterally assembled each other such that peaks221of one spoke210are nested in valleys222of the opposing spoke210and vice versa. This nested arrangement results in a longitudinal engagement interface342between the two matched, mating and interlocked configured surfaces216. As shown inFIG. 18c, sleeve330is then assembled in direction338to circumferentially surround the overlap region341with width332corresponding to the lateral distance between the two surfaces223such that these surfaces223are laterally abutting opening334. Thus, opening334serves to constrain the laterally outward displacement of the two end portions214and thereby to maintain the engagement interface342therebetween. Spokes210are now structurally engaged and locked to each other at the longitudinal engagement interface342to support spoke tension30loads.

In an arrangement with width332generally equal to the lateral distance340between surfaces223as shown inFIG. 18b, the sleeve330may be easily slid over overlap region341to create a retained engagement at engagement interface342. Alternatively, width332may be slightly smaller than this lateral distance340between surfaces such that the sleeve330must be forcibly assembled over overlap region341in a press fit. This press fit serves to provide a laterally inward preload at the engagement interface342, providing greater nesting and friction therebetween to further fortify the engagement interface342as described hereinabove.

While my above description contains many specificities, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of embodiments thereof. It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible to modification of form, size, and arrangement of parts and details of operation. For example:

While the connecting element of the present invention may be directly connected to the bracing element (such as the rim or the hub), there are many cases where it is desirable to include one or more intermediate connecting elements to facilitate this connection. For example, the connecting element may engage an intermediate connecting element and the intermediate connecting element may engage the bracing element.

While the embodiments described herein do not mention the use of adhesive or bonding agent, it is envisioned that the use of adhesive within the engagement interface may be utilized to augment the strength of the crimped joinder. In an exemplary arrangement, an epoxy paste adhesive may be applied to the engagement interface. After the adhesive is cured, the adhesion created by the adhesive may serve to further augment the joinder between the spoke and the connector.

The embodiments shown here show the spokes being held in tension, in the construction of tension-spoke wheels where spoke tension30load is directed longitudinally inwardly. This is for common illustration purposes only. It is understood that the spokes of these embodiments may alternatively be configured to be held in compression, corresponding to construction of compression-spoke wheels where spoke tension30load is directed longitudinally outwardly.

The embodiments ofFIGS. 14a-eand 15a-edescribe a singular connecting element (i.e. connectors386and286) that is deformed such that two laterally opposed portions of the single connecting element are laterally displaced to provide an overlie engagement with the spoke (400and230) to resist spoke tension forces30therebetween. The embodiments ofFIGS. 11a-e,12,13a-e,16, and17a-cdescribe a connecting element as an assembly that includes two discreet elements that are laterally displaced to provide an overlie engagement with the spoke to resist spoke tension forces30therebetween. It is further envisioned that a connecting element assembly may alternatively include three or more discreet elements that are laterally displaced to provide an overlie engagement with the spoke to resist spoke tension forces30therebetween. It is further envisioned that a singular connecting element may be deformed such that three or more portions of a single connecting element are laterally displaced to provide an overlie engagement with the spoke (400and230) to resist spoke tension forces30therebetween.

While the above description is particularly focused on bicycle or vehicle wheel spokes as tensile elements, and this is the preferred embodiment of the present invention, however it is envisioned that the present invention may be adapted to applications involving a wide range of tensile element applications outside of vehicle wheel spoke applications. Some alternative exemplary tensile element applications may include control cables, guy wires, fiber optic cables, overhead high-tension lines, architectural and infrastructure cabling, pre-stressed rebar, etc.

Thus, the present invention provides a vehicle wheel that is inexpensive to produce, lends itself easily to high-volume manufacturing methods, is light in weight and is strong and reliable. Further, the present invention allows the connector to include geometry to optimize its engagement with the bracing element and/or an intermediate element. Further still, the present invention reduces wheel weight by facilitating the utilization of light weight materials, by allowing greater freedom in geometry to optimize the design, by facilitating the use of fiber reinforced spokes. Yet further, the present invention increases the strength and reliability of the wheel by reducing stresses in components and connections and by eliminating any clearances or relative movement between the hub and spokes.