Bicycle crank arm and insert therefore

Information

  • Patent Grant
  • 12024261
  • Patent Number
    12,024,261
  • Date Filed
    Monday, August 30, 2021
    3 years ago
  • Date Issued
    Tuesday, July 2, 2024
    5 months ago
Abstract
A crank arm for a bicycle may include a body extending along a body axis and having a first body end and a second body end axially spaced apart from the first body end. The insert may also include an insert provided toward the first body end. The insert may include a base portion having a radially outer surface. At least one extension may extend outwardly from the radially outer surface and may be encased within a corresponding recess in the body whereby relative planar movement between the body and the at least one extension in a first plane. The retaining portion may have a retaining portion width measured in the first direction and the retaining width may be greater than the throat width thereby inhibiting relative radial movement between the at least one extension and the recess and preventing radial extraction of the extension from the corresponding recess.
Description
FIELD

The present invention relates to bicycle components such as crank arms and methods for making bicycle components.


BACKGROUND

US Patent Publication No. 2005/0199092 (Feltrin et al.) discloses an insert for a bicycle pedal crank that is made from unidirectional structural fibers incorporated in a polymeric material and coupled according to two distinct directions. The insert has a connection portion to connect to a part of the bicycle and a fastening portion to fasten the insert to the body of the crank arm.


SUMMARY

This summary is intended to introduce the reader to the more detailed description that follows and not to limit or define any claimed or as yet unclaimed invention. One or more inventions may reside in any combination or sub-combination of the elements or process steps disclosed in any part of this document including its claims and figures.


Known techniques for securing an insert within a body of a crank arm formed from a dissimilar material have generally failed to provide a satisfactory crank arm. In instances where the insert is formed from a material having a different co-efficient of thermal expansion, thermal shrinkage of the insert (for example when the crank arm is cooled to room temperature after being formed at a relatively high temperature) tends to loosen the connection between the insert and the body as the insert shrinks more than the body. This can lead to relative movement between the insert and the body when the crank arm is in use. Such relative movement may be undesirable as it may reduce pedaling efficiency, promote or accelerate wear of the body or insert and/or lead to the insert falling out or otherwise becoming separated from the body.


According to one broad embodiment of the teachings described herein, a crank arm for a bicycle may include a body extending along a body axis and having a first body end and a second body end axially spaced apart from the first body end. An insert may be provided toward the first body end. The insert may extend along an insert axis, define a radial direction orthogonal to the insert axis and include a base portion. The base portion may have a radially outer surface surrounding an axially extending aperture extending through the base portion. The aperture may be configured to receive a fastener for connecting the crank arm to another component of the bicycle. At least one extension may extend outwardly from the radially outer surface. The at least one extension may be encased within a corresponding recess in the body, whereby relative planar movement between the body and the at least one extension in a first plane orthogonal to the radial direction is restrained. The at least one extension may include a neck adjacent the radially outer surface and a retaining portion spaced radially outward from the neck. The neck may extend through a throat region of the corresponding recess and having a neck width measured in a first direction parallel to the first plane. The throat region may have a throat width measured in the first direction. The retaining portion may have a retaining width measured in the first direction and the retaining width may be greater than the throat width thereby inhibiting relative radial movement between the at least one extension and the recess and preventing radial extraction of the at least one extension from the corresponding recess.


The body may be formed from a body material having a first coefficient of thermal expansion and the insert is formed from an insert material having a second coefficient of thermal expansion. The second coefficient of thermal expansion may be greater than the first coefficient of thermal expansion. Shrinkage of the insert relative to the body cannot radially extract the at least one extension from the cavity.


The extension may also include opposing first and second extension sidewalls spaced apart from each other in the first direction. Each extension sidewall may extend between the neck and the retaining portion. The first sidewall may be generally planar and may be inclined at a first angle relative to the radial direction so that the extension generally narrows from the retaining portion to the neck end thereby wedging the extension within the recess to inhibit relative radial movement therebetween.


The recess may include a generally planar first recess wall inclined at the first angle relative to the radial direction. The first extension sidewall opposing and bearing against the first recess wall whereby shrinkage of the insert relative to the body increases the magnitude of a first engagement force exerted between the first extension sidewall and the first recess wall thereby wedging the at least one extension more tightly within the recess in the first direction.


The second extension sidewall may be generally planar and may be inclined at a second angle relative to the radial direction, the first and second extension sidewall being convergent toward the neck of the extension.


The first angle may be generally equal in magnitude to the second angle.


The recess may include a generally planar second recess wall inclined at the second angle relative to the radial direction. The second extension sidewall opposing and bearing against the second recess wall whereby shrinkage of the insert relative to the body increases the magnitude of a second engagement force exerted between the second extension sidewall and the second recess wall.


The neck has a neck depth measured in a second direction parallel to the insert axis. The retaining portion may have a retaining depth measured in the second direction and the throat may have a throat depth measured in the second direction. The throat depth may be equal to or greater than the neck depth and may be less than the retaining depth.


The extension may also include a third extension sidewall wall generally bounded by the first extension sidewall, the second extension sidewall, the retaining portion and the neck. The third extension sidewall may be generally planar and inclined at a third angle relative to the radial direction so that the extension is generally tapered in the second direction between the retaining portion and the neck.


The recess may include a generally planar third recess wall inclined at the third angle relative to the radial direction. The third extension sidewall opposing and bearing against the third recess wall whereby shrinkage of the insert relative to the body increases the magnitude of a third engagement force exerted between the third extension sidewall and the third recess wall thereby wedging the at least one extension more tightly within the recess in the second direction.


The extension may also include a fourth extension sidewall spaced apart from the third extension sidewall in the second direction and generally bounded by the first and second extension sidewalls, the retaining portion and the neck, the fourth extension sidewall and the third extension sidewall being generally convergent toward the neck of the extension.


The fourth sidewall may be generally planar and extends in the radial direction.


The at least one extension may include a first plurality of extensions circumferentially spaced apart from each other around a circumference of the radially outer surface of the insert.


A second plurality of extensions may be circumferentially spaced apart from each other around the circumference of the radially outer surface of the insert and axially spaced apart from the first plurality of extensions along the insert axis.


Each extension in the second plurality of extensions may be generally opposite a corresponding one of the extensions in the first plurality of extensions and may be spaced apart from the corresponding one of the extensions in the first plurality of extensions in the second direction.


The fourth extension side wall of each extension in the first plurality of extension may be opposite the fourth extension side wall of one corresponding extension in the second plurality of extensions.


The retaining portion may form the radially outermost portion of the extension.


A second insert may be provided toward the second body end. The second insert may extend along a second insert axis and may define a second radial direction orthogonal to the second insert axis. The second insert may include a second base portion having a second radially outer surface and at least one second extension extending outwardly from the second radially outer surface. The at least one second extension may be encased within a corresponding second recess in the body, whereby relative planar movement between the body and the at least one second extension in a second plane orthogonal to the second radial direction is restrained.


The at least one second extension may include a second neck adjacent the second radially outer surface and a second retaining portion spaced radially outward from the second neck. The second neck may extend through a second throat region of the corresponding second recess and may have a second neck width measured in a fifth direction parallel to the second plane. The retaining portion may have a second retaining width measured in the fifth direction and the second retaining width being greater than the second neck width thereby preventing radial extraction of the at least one second extension from the corresponding second recess.


According to another broad aspect of the teachings described herein, a crank arm for a bicycle may include a body having a first end and a second end axially spaced apart from the first end along a body axis. An insert may be positioned within the body toward the first end. The insert may extend along an insert axis, define a radial direction orthogonal to the insert axis and have a radially outer surface. The insert may comprise a base portion having a radially outer surface and a plurality of extensions extending outwardly from the radially outer surface. Each extension may be encased within a corresponding recess in the body, whereby relative planar movement between the body and each extension in a first plane orthogonal to the radial direction is restrained. Each extension may comprise a neck adjacent the radially outer surface and a retaining portion spaced radially outward from the neck. Each neck may extend through a throat region of one corresponding recess and may have a neck cross-sectional area measured in a second plane orthogonal to the radial direction. The throat may have a throat cross-sectional area measured in the second plane and the retaining portion may have a retaining cross-sectional area measured in third plane parallel to the second plane. The retaining cross-sectional area may be greater than the neck portion cross-sectional area and the throat cross-sectional area thereby preventing radial extraction of each extension from the one corresponding recess.


The body may be formed from a body material having a first coefficient of thermal expansion and the insert is formed from an insert material having a second coefficient of thermal expansion, the second coefficient of thermal expansion being different than the first coefficient of thermal expansion and shrinkage of the insert relative to the body increases the magnitude of a retention force exerted between the body and the retaining portion of each insert.


A method of forming a crank arm during the moulding process is provided, including the steps of: a) providing an insert made of a material, the insert defining an aperture, the insert having a plurality of extensions, each of the extensions fitting within a corresponding recess, wherein the neck of the insertions is narrower than a distance between a first side of the insertion and a second side of the insertion; b) heating the crank arm whereby composite material cures around the extensions, thereby defining a crank arm having a body made of the composite material, the body defining a plurality of recesses, each of the recesses having an opening, and at least one of the recesses having a width from a first side of the recess to a second side of the recess exceeding the length of the opening; c) cooling the crank arm, whereby the material shrinks relative to the composite material during cooling of the crank arm.





DRAWINGS

The following figures set forth embodiments of the invention in which like reference numerals denote like parts. Embodiments of the invention are illustrated by way of example and not by way of limitation in the accompanying figures.



FIG. 1 is a perspective view of a crank arm;



FIG. 2 is a perspective view of an example of an insert for the crank arm of FIG. 1;



FIG. 3 is a cross-sectional view of the insert of FIG. 2, taken along line 3-3;



FIG. 4 is a cross-sectional view of the insert of FIG. 2, taken along line 4-4;



FIG. 5 is cross-sectional view of a portion of the crank arm of FIG. 1, taken along line 5-5;



FIG. 6 is an enlarged view of a portion of the cross-sectional view of FIG. 5;



FIG. 7 is a cross-sectional view of a portion of the crank arm of FIG. 1, taken along line 7-7;



FIG. 8 is the cross-sectional view of FIG. 5 before shrinkage of the insert;



FIG. 9 is an enlarged view of a portion of the cross-sectional view of FIG. 8;



FIG. 10 is the cross-sectional view of FIG. 7 before shrinkage of the insert.





DETAILED DESCRIPTION

Various apparatuses or processes will be described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover processes or apparatuses that differ from those described below. The claimed inventions are not limited to apparatuses or processes having all of the features of any one apparatus or process described below or to features common to multiple or all of the apparatuses described below. It is possible that an apparatus or process described below is not an embodiment of any claimed invention. Any invention disclosed in an apparatus or process described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicants, inventors or owners do not intend to abandon, disclaim or dedicate to the public any such invention by its disclosure in this document.


Bicycle crank arms typically form part of the crankset or chainset of a bicycle. The crank arms generally extend between the bottom bracket on the bicycle frame and the pedals. A conventional pedal bicycle has two crank arms, typically mounted 180 degrees out of phase from each other. Crank arms can be made from any suitable material having the required strength to transfer pedaling force from the user's legs to the crankset. For example, known crank arms have been made from metals, such as steel and aluminium, and composite materials, such as carbon fibre and other materials.


The apparatus and system according to the invention uses a series of widening recesses within a crank arm to mechanically lock an insert to the carbon fibre during the cooling that takes place after the moulding process. As the insert shrinks it follows the recess wall of the hollow made by the insert rather than shrinking away from it. The insert angle can be chosen to be equal to, greater than or less than the angle of shrinkage at any particular location of the insert. Changing the angle changes the gap (or interference) produced during the shrinkage thereby changing the locking characteristics and allowing the crank arm to be optimized for a given loading.


Crank arms can be connected to the bottom bracket and/or pedals using spindles, bolts, pins or other suitable rotatable connection mechanism. Some composite materials used to form crank arms are not well suited to connect to or support a rotatable connection mechanism. For example, crank arms formed from carbon fibre may be relatively strong and lightweight, but the carbon fibre material may not have sufficient mechanical properties to withstand the loading and stress concentrations exerted by the rotatable connection mechanism.


One technique to help address this problem is to manufacture a crank arm having a body that is formed from a composite material and to provide one or more inserts at the ends of the crank arm where it is connected to the pedal or bottom bracket. Such inserts may be formed from a different material than the body of the crank arm. For example, the insert material may be selected to have sufficient strength and other material properties to support the rotatable connection mechanism, including, for example, aluminum, titanium, steel, magnesium, stainless steel, or various plastics such as polyurethane, polypropylene, or polycarbonate. Using the combination of a composite body and metal insert may allow the crank arm to generally benefit from the desirable properties of the composite material (e.g. strength, low weight, etc.) while still having sufficient connection strength.


In crank arms of this configuration, the quality of the connection between the insert and the body of the crank arm can affect the quality and/or durability of the assembled crank arm. Typically, the insert material will have a larger co-efficient of thermal expansion than the composite body material, which can result in shrinkage of the insert relative to the body, for example when the crank arm is cooled after the composite material molding process. Such shrinkage can lead to a loosening of the insert within the body. Loosening of the insert can lead to rattling, unwanted rotation of the insert relative to the body, fatigue of the body portion and ultimately failure of the crank arm. The teachings herein describe an example of a connection between an insert and crank arm body that may help mitigate and/or eliminate loosening of the insert caused by differential thermal expansion.


[Referring to FIG. 1, one example of a crank arm 100 includes a body 102 a first insert 104 and a second insert 106. Optionally, while currently illustrated with two inserts 104, 106, a crank arm 100 may be configured to include a different number of inserts, including, for example, only one insert.


In the illustrated example, the body 102 is generally elongate and extends along a body axis 108 between a first end 110, for connecting to bottom bracket of a bicycle, and a second end 112, for connecting to a pedal assembly.


The body 102 is formed from a body material, and the inserts 104 and 106 are formed from an insert material, which can be different than the body material. In the illustrated example, the body 102 is formed from carbon fiber and the inserts 104, 106 are formed from aluminium. Alternatively, the body 102 may be formed from any other suitable material, including, for example, composite materials such as fiberglass, Kevlar®, boron fiber or beryllium fiber, or metal or plastic. The inserts 104, 106 may be formed from any suitable material that has the desired strength to support the rotatable connection between the crank arm and other bicycle components including, for example, steel, titanium, other metals and/or plastics.


The inserts 104, 106 are configured to be mounted within the body 102, and to facilitate connection with the bottom bracket and pedal assembly, respectively. Each insert 104, 106 includes a central bore or aperture 114 and 116 that is configured to accommodate a fastener. The bores 114 and 116 may be threaded or otherwise configured to mate with a corresponding fastener. In the illustrated example, both inserts 104 and 106 extend along respective insert axes 118 and 120. The inserts 104, 106 in the crank arm 100 can be identical, or may be different from each other. Providing differently configured inserts may help facilitate different types of connections between the crank arm 100 and the bottom bracket and pedal assembly. For simplicity, insert 106 will be described in greater detail herein, but it is understood that insert 104 can include identical and/or analogous features.


Referring to FIG. 2, insert 106 includes a generally cylindrical body portion 122 surrounding the bore 116 and having a radially outer surface 124 (see FIG. 3). To help secure the insert 106 within the body 102, the insert 106 can include one or more anchor members 125 that are configured to be embedded in and encased by the body 102. The anchor members 125 can be configured to help inhibit rotation of the insert 106 relative to the body 102 about the insert axis 120, and/or to help inhibit translation of the insert 106 relative to the body 102 along the insert axis 120.


In the illustrated example, the anchor members 125 include a plurality of extensions 126 extending generally outwardly from the radially outer surface 124 (see FIG. 3) of the insert 106. The extensions 126 include a first set of extensions 126a that are circumferentially spaced apart from each other about the periphery or circumference of the insert 106 by a first spacing distance 128 (illustrated as a centre-to-centre distance), and are arranged to provide a first ring of extensions 130 (see FIG. 4). The first ring of extensions 130 is axially positioned toward a first end 132 of the insert 106.


The extensions 126 also include a second set of extensions 126b that are circumferentially spaced apart from each other about the periphery of the insert 106 by a second spacing distance 134, and are arranged to provide a second ring of extensions 136 (see FIG. 4). Referring to FIG. 4, the second ring of extensions 136 is axially positioned toward a second end 138 of the insert 106 and is axially spaced apart from the first ring of extensions by a ring spacing distance 140.


In the illustrated example, each extension 126a in the first ring 130 is circumferentially aligned with an opposing extension 126b in the second ring 136. In this configuration, axial gaps 142 are provided between opposing extensions 126a and 126b. Arranging the extensions 126a and 126b in this pattern may help simplify the manufacturing of the insert 106. Alternatively, the extensions 126a and 126b may be configured so that extensions 126a in the first ring 130 are circumferentially offset from extensions 126b in the second ring 136. While illustrated with 10 extensions in each of the first and second rings, the insert may be provided with any suitable number of extensions, including, for example, between about 1 and about 40 extensions or more, and preferably between about 4 and about 30 extensions.


Referring to FIG. 3, each extension 126a extends outwardly from a neck portion 144 adjacent the radially outer surface 124 of the insert 106 and distal end or tip 146 that is radially outboard from the neck portion 144 in the radial direction 148. The tip 146 includes a radially outwardly facing end face 150. In the illustrated example, each extension includes four, generally planar sidewalls 152, 154, 156 and 158 (FIG. 4) that extend between the neck 144 and the tip 146. Alternatively, the extensions 126 may be of any other suitable shape, including, for example, spherical, conical, pyramidal and other shapes that can be configured to function as described herein.


Referring to FIG. 3, the neck portion 144 defines a neck width 160, measured in a plane 162 that is orthogonal to the radial direction 148, and, referring to FIG. 4, a neck depth 164, measured in the axial direction. The neck width 160 and neck depth 164 can be any suitable size based on the overall size of the crank arm 100 and the expected loading conditions, and can each be, for example, between about 2 mm and about 15 mm or more, and/or between about 3 mm and about 10 mm. The neck portion 144 also defines a radial cross-sectional area measure in plane 162.


Each extension 126a also includes a retaining portion 166 that is configured to help lock the extensions 126a within respective cavities formed in the carbon fibre body 102 and to help inhibit movement of the insert 106 relative to the body 102, as explained in more detail below. The retaining portion 166 is a portion of the extension 126a that is generally wider and/or deeper than the neck portion 144. The retaining portion 166 defines a retaining portion width 168, measured in a plane 170 that is orthogonal to the radial direction 148 and is parallel to and radially outboard from the plane 162.


The retaining portion width 168 is selected to be larger than the neck portion width 160, and can be between about 3 mm to about 20 mm or more. The retaining portion 166 also defines a retaining portion depth 172 (FIG. 3) measured in the insert axial direction. The retaining portion depth 172 is selected to be larger than the neck portion depth 164, and can be between about 3 mm to about 20 mm or more. The retaining portion 166 also defines a retaining portion radial cross-sectional area, measured in plane 170, that is greater than the neck portion cross-sectional area. In this configuration, each extension 126a generally tapers from its retaining portion 166 to its neck portion 144.


In the illustrated example, the retaining portion 166 is provided at the tip 146 of the extension 126a (i.e. is the radially outermost portion of the extension 126a), such that the extension 126a generally narrows or tapers from the tip 146 to the neck portion 144. Alternatively, the extension 126a may be configured such that the retaining portion 166 (e.g. the portion with the largest radial cross-sectional area) is positioned radially intermediate the neck portion 144 and the tip 146 (for example if the extension were spherical).


Referring to FIG. 3, sidewalls 154 and 158 generally oppose each other in the circumferential direction and are each inclined relative to the radial direction by a respective incline angle 174 and 176. The sidewalls 154, 158 are inclined in such a manner that the extension 126a narrows in the circumferential direction from the retaining portion 166 to the neck portion 144 and so that they generally converge toward the insert axis 120. The incline angles 174 and 176 can be any suitable angle, including, for example between about 2 degrees and about 30 degrees or more, and is preferably between about 7 degrees and about 15 degrees. While illustrated as being generally equal, incline angles 174 and 176 may be the same or different.


Referring to FIG. 4, sidewalls 152 and 156 generally oppose each other in the insert axial direction. In the illustrated example, sidewall 156 is parallel to a plane 178 that is orthogonal to the insert axis 120 whereas sidewall 152 is inclined at an angle 180 relative to the plane 178. The angle 180 can be any suitable angle, and can be between about 2 degrees and about 30 degrees or more, and is preferably between about 7 degrees and about 15 degrees. In this configuration, the extension 126a generally tapers from the retaining portion 166 to the neck portion 144 in the insert axial direction, and the sidewalls 152 and 156 generally converge toward the plane 178. While illustrated with only one of sidewalls 152 and 156 inclined, alternatively the extension 126a can be configured so that both sidewalls 152 and 156 are inclined relative to plane 178, and converge toward the plane 178.


In the illustrated example, inclined sidewalls 152, 154 and 158 each overhang or overlie a portion of the radially outer surface 124 and define a respective cavity 182, 184 and 188 that can be filled with body material (e.g. carbon fibre material and epoxy resin) during the crank arm manufacturing process (explained in more detail below). This may help anchor the extensions 126a within the body 102. In contrast, in the illustrated example, non-inclined sidewall 156 does not overhang the radially outer surface 124 of the insert base portion 122 and does not define a corresponding cavity.


While illustrated with two rings 130 and 136 of ten extensions 126 each, alternatively, the insert 126a may include a different number of and/or configuration of extensions 126, and need not include two axially spaced apart rings 130 and 136 of extensions. The extensions 126 may be provided in any suitable pattern or configuration, and may include only a single set of extensions 126 and/or be configured so that each extension extends substantially the entire axial length of the insert.


Referring to FIG. 8, in the illustrated example, the crank arm is formed by a molding process in which both the body 102 and insert 106 are contained within a heated mold and held at elevated temperatures (for example temperatures greater than 100 degrees Celsius). FIG. 8 is a cross-sectional view of a portion of the crank arm 100 while it is at the elevated, molding temperature. Referring to FIG. 9, during this molding process the carbon fibre body material is molded around the extensions 126a thereby covering sidewalls 154 and 158 and is forced into the cavities 184 and 188 (illustrated as hatched areas in this FIG. 9). Encasing the extensions 126a in this manner may inhibit relative rotation of the insert 106 relative to the body 102.


Referring to FIG. 10, during the molding process the carbon fibre body material also encases sidewalls 152 and 156 and is forced into the cavity 182 (illustrated as hatched areas in FIG. 10). In the illustrated example, the extensions 126a are completely encased within the body material such that all of the sidewalls 152, 154, 156 and 158 are covered by body material. Encasing the extensions 126 in this manner may inhibit movement of the extensions 126a, and therefore the insert 106, relative to the body 102 in insert axial direction.


After the molding process is complete, the molded crank arm is then removed from mold and cooled to room temperature. During the cooling phase the body 102 and the inserts 104 and 106 may shrink as a result of thermal contraction.



FIGS. 5-7 illustrate the insert 106 and body 102 after the crank arm 100 has cooled to room temperature. Referring to FIG. 5, in the current example, when the insert 106 is molded within the body 102 each extension 126 is embedded within the body material and becomes encased in a corresponding recess 190 formed in the body 102. The recesses 190 are created as the body material is forced around the extensions 126 during molding, and the shape of each recesses 190 generally matches the shape of its contained extension 126.


In the illustrated example, each recess includes four recess sidewalls corresponding to opposing extension sidewalls. Referring to FIG. 6, recess 190a includes sidewalls 194 and 198 opposing extension sidewalls 154 and 158 respectively. Referring to FIG. 7, recess 190a also includes sidewalls 192 and 196, opposing extension sidewalls 152 and 156 respectively.


The recess 190a also includes a recess end wall 200 overlying the extension end face 150, and defines an opening or throat region 204 through which the neck portion 144 extends. The throat region 204 surrounds the neck portion 144 and defines a throat width 206 measure in the same plane 162 as the neck width 160 (FIG. 6) and a throat depth 208 measured in the same direction as the neck depth 164 (FIG. 7). The throat width 206 is equal to or slightly greater than the neck width 160, and the throat width 206 is less than the retaining portion width 168. Similarly, in the illustrated example, the throat depth 208 is equal to or slightly greater than the neck depth 164 and is less than the retaining portion depth 172. In this configuration, the radial cross-sectional area of the throat (measured in plane 162) is equal to or greater than the cross-sectional area of the neck portion 144 and is less than the cross-sectional area of the retaining portion 166.


Referring to FIGS. 9 and 10, when the insert 106 and body 102 are both at elevated temperatures during the molding process, each recess wall 192, 194, 196 and 198 is in contact with its opposing extension sidewall 152, 154, 156 and 158, and endwall 200 is in contact with end face 150.


As aluminium has a greater co-efficient of thermal expansion than carbon fiber, when the molded crank arm cools, the inserts 104 and 106 will tend to thermally contract or shrink more than the carbon fibre body 102. When the extension 126a cools it may tend to shrink radially.


Referring to FIGS. 6 and 7, in the illustrated example, the extension 126a shrinks by such an amount that the extension end face 150 becomes axially spaced apart from the recess endwall 200 and a gap 202 is created. Absent a countering force, the presence of such a gap 202 may permit the extension to move radially relative to the body resulting in loosening of the insert. However, in the illustrated example, corresponding shrinkage of the other extensions 126a around the perimeter of the insert 106 create balancing forces that co-operate to inhibit movement of the insert 106 in the radial direction 148 relative to the body 102.


Referring to FIG. 6, as the insert 106 shrinks the inclined or wedge-like configuration of extension sidewalls 154 and 158, and corresponding recess sidewalls 194 and 198, allows the extension sidewalls 154 and 158 to slide along the recess sidewalls 194 and 198. In this configuration, as the insert 106 shrinks the sidewalls 154 and 158 do not lose contact with their respective recess sidewalls 194 and 198. Instead, due to its tapered nature, the extension 126a may actually become more tightly seated within its cavity 190a and the sidewalls 154 and 158 will be more tightly wedged against the recess sidewalls 194 and 198. This may allow the magnitude of the force acting between the extension sidewalls 154 and 158 and recess sidewalls 194 and 198 to remain constant or increase as the insert 106 shrinks. Increasing the force acting on the extension 126a in the circumferential direction may help hold the insert 106 firmly in place and may help inhibit relative rotation of the insert 106 (about the insert axis 120) relative to the body 102. While illustrated as a two-side wedge configuration (both sidewalls 154 and 158 are inclined) to help provide a balanced circumferential wedging force, a similar wedging effect in the circumferential direction may be achieved if only one of sidewalls 154 and 158 is inclined.


Similarly, the wedge-like configuration of extension sidewall 152 and corresponding recess sidewall 192 can provide a wedging or tightening effect in the insert axial direction as the insert shrinks 106. Providing such a wedge-like configuration in the axial direction may help firmly hold the insert 106 in place axially, and may help prevent translation of the insert 106 (along the insert axis 120) relative to the body 102. In the illustrated example, the axial wedging features of extensions 126a in the first ring 130 are balanced by opposite axial wedging features of extensions 126b in the second ring 136.


Due to the inclined configuration of sidewalls 152, 154 and 158 and the generally wedge-like nature of the extensions 126 the magnitude of the engagement forces holding the extensions 126 in place after they have cooled can exceed the magnitude of the surface friction between the extension sidewalls 152, 154 and 158 recess sidewalls 192, 194 and 198.


Increasing the reaction or engagement forces acting on the extension sidewalls 152, 154 and 158 may increase the stress exerted on the neck portion 144 of the extension 126. Varying the inclination angle of the sidewalls 152, 154 and 158, the cross-sectional area of the neck portion 144, the material of the insert 106 or any combination thereof may allow the insert 106 to be configured to resist the elevated stress caused by the expected thermal shrinkage.


The wedge-like configuration of the extensions 126 may also increase engagement force between and extension 126 and its surrounding cavity 190 may also increase when the insert is under load, for example when the crank arm is in use.


What has been described above has been intended to be illustrative of the invention and non-limiting and it will be understood by persons skilled in the art that other variants and modifications may be made without departing from the scope of the invention as defined in the claims appended hereto.

Claims
  • 1. A bicycle crank arm comprising: a bicycle crank arm body extending along a body axis and having a first body end and a second body end; anda bicycle crank arm insert mounted within said bicycle crank arm body at said first body end, said bicycle crank arm insert further comprising: a base portion, the base portion having a radially outer surface surrounding an aperture; andat least one extension disposed in a first ring of extensions, said at least one extension extending outwardly from said radially outer surface, said at least one extension configured to be at least partially encased within said bicycle crank arm body, said at least one extension comprising: a neck adjacent said radially outer surface; anda retaining portion spaced radially outward from said neck, said neck configured to extend through a throat region of said bicycle crank arm body, said neck having a neck width measured in a first direction, said throat region having a throat width measured in said first direction, the retaining portion having a retaining width measured in said first direction and said retaining width being greater than said throat width such that said at least one extension comprises a sidewall extending between said throat region and said retaining portion, said neck inhibiting relative radial movement between said at least one extension of said bicycle crank arm insert and said bicycle crank arm body, and said neck inhibiting radial extraction of said at least one extension from a corresponding recess in said bicycle crank arm body;wherein said first ring of said extensions comprises: a first plurality of extensions circumferentially spaced apart from each other around a circumference of said radially outer surface of said bicycle crank arm insert; andwherein said second ring of said extensions comprises: a second plurality of extensions disposed in a second ring of extensions, said second plurality of extensions circumferentially spaced apart from each other around said circumference of said radially outer surface of said bicycle crank arm insert, said second ring of said extensions axially spaced apart from said first ring of said extensions along an insert axis.
  • 2. The bicycle crank arm insert of claim 1, wherein said bicycle crank arm insert is formed from a material having a coefficient of thermal expansion which differs from a coefficient of thermal expansion of said bicycle crank arm body such that shrinkage of said bicycle crank arm insert relative to said bicycle crank arm body does not result in said radial extraction of said bicycle crank arm insert from said bicycle crank arm body.
  • 3. The bicycle crank arm insert of claim 1, wherein said at least one extension further comprises: a first extension sidewall; anda second extension sidewall, said first extension sidewall said second extension sidewall disposed opposing each other, said first extension sidewall and said second extension sidewall spaced apart from each other in said first direction, said first extension sidewall and said second extension sidewall extending between said neck and said retaining portion, said first extension sidewall being planar and being inclined at a first angle relative to a radial direction such that the said at least one extension narrows from said retaining portion to said neck to wedge said at least one extension within said corresponding recess in said bicycle crank arm body to inhibit relative movement, along said radial direction, between said bicycle crank arm insert and said bicycle crank arm body.
  • 4. The bicycle crank arm insert of claim 3, wherein said second extension sidewall is planar and is inclined at a second angle relative to said radial direction, said first extension sidewall and said second extension sidewall being convergent toward said neck of said at least one extension.
  • 5. The bicycle crank arm insert of claim 4, wherein said first angle is approximately equal in magnitude to said second angle.
  • 6. The bicycle crank arm insert of claim 4, wherein said at least one extension further comprises: a third extension sidewall wall bounded by said first extension sidewall and said second extension sidewall, said retaining portion and said neck, said third extension sidewall being planar and inclined at a third angle relative to said radial direction such that said at least one extension is tapered in a second direction between said retaining portion and said neck.
  • 7. The bicycle crank arm insert of claim 6, wherein said at least one extension further comprises: a fourth extension sidewall spaced apart from said third extension sidewall and bounded by said first extension sidewall and second extension sidewall, said retaining portion and said neck, said fourth extension sidewall and said third extension sidewall being convergent toward said neck of said at least one extension.
  • 8. The bicycle crank arm insert of claim 7, wherein said fourth extension sidewall is planar and extends in said radial direction.
  • 9. The bicycle crank arm insert of claim 1, wherein said neck has a neck depth measured in a direction parallel to said insert axis, said retaining portion has a retaining depth measured in said direction parallel to said insert axis, and said throat region has a throat depth measured in said direction parallel to said insert axis, said throat depth being equal to or greater than said neck depth and said throat depth being less than said retaining depth.
  • 10. The bicycle crank arm insert of claim 1, wherein said plurality of extensions in said first ring of extensions are circumferentially aligned with respect to said plurality of extensions in said second ring of extensions.
  • 11. The bicycle crank arm insert of claim 10, wherein said fourth extension sidewall of each of said first plurality of extensions of said first ring of extensions is disposed opposite said fourth extension sidewall of each of said second plurality of extensions of said second ring of extensions.
  • 12. The bicycle crank arm insert of claim 1, wherein said plurality of extensions in said first ring of extensions are circumferentially offset with respect to said plurality of extensions in said second ring of extensions.
  • 13. The bicycle crank arm insert of claim 1, wherein said retaining portion forms the radially outermost portion of said at least one extension.
CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of and claims the benefit of co-pending U.S. patent application Ser. No. 17/067,643, filed on Oct. 10, 2020, entitled “BICYCLE CRANK ARM AND INSERT THEREFORE”, and assigned to the assignee of the present application, and is hereby incorporated by reference in its entirety herein. The application Ser. No. 17/067,643 is a continuation application of and claims the benefit of U.S. patent application Ser. No. 15/669,756, filed on Aug. 4, 2017, now U.S. Issued U.S. Pat. No. 10,800,482, entitled “BICYCLE CRANK ARM AND INSERT THEREFORE”, and assigned to the assignee of the present application, and is hereby incorporated by reference in its entirety herein. The application Ser. No. 15/669,756 is a continuation application of and claims the benefit of U.S. patent application Ser. No. 14/341,300, filed on Jun. 25, 2014, now U.S. Issued U.S. Pat. No. 9,725,133, entitled “BICYCLE CRANK ARM AND INSERT THEREFORE”, and assigned to the assignee of the present application, and is hereby incorporated by reference in its entirety herein. The application Ser. No. 14/341,300 is a continuation application of and claims the benefit of U.S. patent application Ser. No. 13/675,304, filed Nov. 13, 2012, now U.S. Issued U.S. Pat. No. 8,820,192, entitled “BICYCLE CRANK ARM AND INSERT THEREFORE”, and assigned to the assignee of the present application, and is hereby incorporated by reference in its entirety herein. The application Ser. No. 13/675,304 is a continuation-in-part application of and claims the benefit of U.S. patent application Ser. No. 12/432,681, filed Apr. 29, 2009, now abandoned, entitled “INSERT FOR BICYCLE CRANK ARM”, and assigned to the assignee of the present application, and is hereby incorporated by reference in its entirety herein.

US Referenced Citations (239)
Number Name Date Kind
2451690 Oehler Oct 1948 A
2468011 Hazel Apr 1949 A
2793571 Way et al. May 1957 A
3168836 Militana Feb 1965 A
3200665 Martin Aug 1965 A
3272027 Wayman Sep 1966 A
3304796 Leege Feb 1967 A
3371549 Ernst Mar 1968 A
3815439 Tarutani Jun 1974 A
3903754 Morroni Sep 1975 A
3905248 Peyrard Sep 1975 A
3987539 Gravener Oct 1976 A
4144773 Addicks Mar 1979 A
4174642 Martin et al. Nov 1979 A
4240303 Mosley Dec 1980 A
4261214 Watanabe et al. Apr 1981 A
RE30758 Lang Oct 1981 E
4318310 Segawa Mar 1982 A
4331043 Shimano May 1982 A
4358967 Kastan Nov 1982 A
4392841 Juy Jul 1983 A
4439172 Segawa Mar 1984 A
4446753 Nagano May 1984 A
4453924 Sugino Jun 1984 A
4475894 Sugino Oct 1984 A
4545691 Kastan et al. Oct 1985 A
4583422 Boyd Apr 1986 A
4586914 Nagano May 1986 A
4594910 Nagano Jun 1986 A
4598608 Ueno Jul 1986 A
4608878 Shimano Sep 1986 A
4722722 Rampe Feb 1988 A
4867733 Yamanoi et al. Sep 1989 A
4889521 Nagano Dec 1989 A
5003840 Hinschlager Apr 1991 A
5192248 Nagano Mar 1993 A
5192249 Nagano Mar 1993 A
5224903 Langhof et al. Jul 1993 A
5226469 Matsumura et al. Jul 1993 A
5246402 Romano Sep 1993 A
5285701 Parachinni Feb 1994 A
5362278 Bergles et al. Nov 1994 A
5413534 Nagano May 1995 A
5451198 Lancaster Sep 1995 A
5738603 Schmidt et al. Apr 1998 A
5830096 Schmidt et al. Nov 1998 A
5852954 Yamanaka Dec 1998 A
5908364 Tanaka Jun 1999 A
5935033 Tseng et al. Aug 1999 A
5947852 Moretz Sep 1999 A
5984817 Schulz Nov 1999 A
6007442 Schmidt Dec 1999 A
6013001 Miyoshi Jan 2000 A
6022284 Bartolozzi et al. Feb 2000 A
6102821 Nakamura Aug 2000 A
6202506 Storck et al. Mar 2001 B1
6203462 Takamori Mar 2001 B1
6564675 Jiang May 2003 B1
6572500 Tetsuka Jun 2003 B2
6656072 Sugita et al. Dec 2003 B2
6666786 Yahata Dec 2003 B2
6755095 Yamanaka Jun 2004 B2
6860171 Nanko et al. Mar 2005 B1
7080574 Chang Jul 2006 B2
7263914 Ording et al. Sep 2007 B2
7267030 French Sep 2007 B2
7462120 Thompson Dec 2008 B1
7503864 Nonoshita et al. Mar 2009 B2
7530290 Lin May 2009 B2
7610832 Guiseppe et al. Nov 2009 B2
7686721 Tabe et al. Mar 2010 B2
7699733 Sakura et al. Apr 2010 B2
7713156 Sakura et al. May 2010 B2
7753815 Saifuddin et al. Jul 2010 B2
7824287 Nonoshita et al. Nov 2010 B2
7850564 Nonoshita Dec 2010 B2
7883437 Braedt Feb 2011 B2
7942771 Kamada May 2011 B2
7967709 Emura et al. Jun 2011 B2
8025304 Smith Sep 2011 B2
8057338 Kamada Nov 2011 B2
8070632 Yuan Dec 2011 B2
8096908 Oishi et al. Jan 2012 B2
8226511 Kamada Jul 2012 B2
8298104 Sakura Oct 2012 B2
8479610 Valle et al. Jul 2013 B2
8550944 Esquibel Oct 2013 B2
8573093 Valle et al. Nov 2013 B2
8616084 Meggiolan Dec 2013 B2
8820192 Staples Sep 2014 B2
8882619 Braedt Nov 2014 B2
8888631 Morita Nov 2014 B2
9016169 Sugimoto et al. Apr 2015 B2
9033835 Blank et al. May 2015 B2
9302733 Schlanger Apr 2016 B2
9302736 Iwai et al. Apr 2016 B2
9308967 Braedt Apr 2016 B2
9328814 Wesling et al. May 2016 B2
9415835 Tokuyama et al. Aug 2016 B2
9440706 Iwai et al. Sep 2016 B2
9463844 Fukunaga Oct 2016 B2
9493211 Reiter et al. Nov 2016 B2
9540070 Watarai et al. Jan 2017 B2
9580144 Bernardele Feb 2017 B2
9631714 Watarai et al. Apr 2017 B2
9677658 Wickliffe Jun 2017 B2
9719590 Reiter et al. Aug 2017 B2
9725133 Staples Aug 2017 B2
9791033 Wickliffe et al. Oct 2017 B2
9869382 Wesling et al. Jan 2018 B2
9914502 Wu Mar 2018 B2
9919763 Iwai et al. Mar 2018 B2
9926038 Fukunaga et al. Mar 2018 B2
9932090 Yoshida et al. Apr 2018 B2
9944351 Braun et al. Apr 2018 B2
9963196 Sugimoto May 2018 B2
9994285 Tokuyama et al. Jun 2018 B2
10040510 Sugimoto et al. Aug 2018 B2
10053186 Braedt et al. Aug 2018 B2
10059400 Tokuyama et al. Aug 2018 B2
10155566 Sugimoto Dec 2018 B2
10221887 Dubois et al. Mar 2019 B2
10358186 Sugimoto Jul 2019 B2
10359106 Akanishi Jul 2019 B2
10359107 Young Jul 2019 B2
10377445 Hirose et al. Aug 2019 B2
10407127 Sugimoto Sep 2019 B2
10443685 Reiter Oct 2019 B2
10507888 Sugimoto Dec 2019 B2
10550925 Akanishi Feb 2020 B2
10562589 Sugimoto et al. Feb 2020 B2
10578201 Reiter et al. Mar 2020 B2
10800482 Staples Oct 2020 B2
10864963 Staples Dec 2020 B2
10994804 Sugimoto May 2021 B2
11014628 Choltco-Devlin et al. May 2021 B2
11130546 Staples Sep 2021 B2
11505277 Yamanaka Nov 2022 B1
20020086753 Yahata Jul 2002 A1
20030097900 Yamanaka May 2003 A1
20030199351 Nichols Oct 2003 A1
20040070166 Valle Apr 2004 A1
20040092352 Chiang May 2004 A1
20040200314 Hermansen et al. Oct 2004 A1
20040204274 Young Oct 2004 A1
20050009656 Preis et al. Jan 2005 A1
20050014590 Wen Jan 2005 A1
20050032596 Nonoshita et al. Feb 2005 A1
20050039570 Nanko et al. Feb 2005 A1
20050072264 Yamanaka Apr 2005 A1
20050081678 Smith Apr 2005 A1
20050090349 Lee Apr 2005 A1
20050199092 Feltrin et al. Sep 2005 A1
20050233850 Andel Oct 2005 A1
20050282671 Emura et al. Dec 2005 A1
20050282672 Nonoshita Dec 2005 A1
20060205549 Nonoshita et al. Sep 2006 A1
20060210734 Lin Sep 2006 A1
20060288819 Dal et al. Dec 2006 A1
20070034043 Feltrin Feb 2007 A1
20070049437 Wickliffe Mar 2007 A1
20070054768 Miyazawa Mar 2007 A1
20070111833 Young May 2007 A1
20070129193 Nonoshita et al. Jun 2007 A1
20070137425 Dal et al. Jun 2007 A1
20070173364 Renshaw Jul 2007 A1
20070186718 Chiang Aug 2007 A1
20070199403 Ciavatta et al. Aug 2007 A1
20070227293 Valle Oct 2007 A1
20070227294 Valle Oct 2007 A1
20070265122 Emura et al. Nov 2007 A1
20070270261 Sakura et al. Nov 2007 A1
20070283781 Meggiolan Dec 2007 A1
20080028887 Valle et al. Feb 2008 A1
20080120845 Hama May 2008 A1
20080176691 Saifuddin et al. Jul 2008 A1
20080202284 Valle et al. Aug 2008 A1
20080207369 Bouchez Aug 2008 A1
20080272572 Tsai Nov 2008 A1
20080314193 Meggiolan Dec 2008 A1
20090042681 Dal et al. Feb 2009 A1
20090042682 Dal et al. Feb 2009 A1
20090105024 Sakura et al. Apr 2009 A1
20090236777 Chiang Sep 2009 A1
20090243160 Chiang Oct 2009 A1
20090247337 Sakura et al. Oct 2009 A1
20100064845 French Mar 2010 A1
20100093494 Smith Apr 2010 A1
20100326233 Schlanger Dec 2010 A1
20110126666 McAinsh Jun 2011 A1
20110167943 Lermen et al. Jul 2011 A1
20110251008 Schmitz et al. Oct 2011 A1
20110319209 Huang et al. Dec 2011 A1
20120172165 Schroedl Jul 2012 A1
20130011215 Wells Jan 2013 A1
20130087013 Sugimoto et al. Apr 2013 A1
20130139642 Reiter et al. Jun 2013 A1
20130184110 Reiter Jul 2013 A1
20140335987 Iwai et al. Nov 2014 A1
20150082939 Meyer et al. Mar 2015 A1
20150152231 Ohki et al. Jun 2015 A1
20150175241 Malloy Jun 2015 A1
20150176692 Roh Jun 2015 A1
20150198231 Emura Jul 2015 A1
20150210352 Sugimoto Jul 2015 A1
20150210353 Tokuyama et al. Jul 2015 A1
20150211623 Inui Jul 2015 A1
20150217834 Iwai et al. Aug 2015 A1
20150337943 Sugimoto Nov 2015 A1
20150360749 Iwai et al. Dec 2015 A1
20150362057 Wesling et al. Dec 2015 A1
20160114859 Tsai et al. Apr 2016 A1
20160272279 Yoshida et al. Sep 2016 A1
20170029066 Fukunaga et al. Feb 2017 A1
20170146109 Reiter et al. May 2017 A1
20170174288 Wu Jun 2017 A1
20170183060 Braedt Jun 2017 A1
20170234418 Barefoot et al. Aug 2017 A1
20170247081 Sugimoto Aug 2017 A1
20170274960 Dubois et al. Sep 2017 A1
20170292598 Moore et al. Oct 2017 A1
20180037296 Hamamoto Feb 2018 A1
20180043203 Seol Feb 2018 A1
20180057106 Iwai et al. Mar 2018 A1
20180079467 Hirose et al. Mar 2018 A1
20180127057 Sugimoto May 2018 A1
20180134340 Emura May 2018 A1
20180231060 Milanesio et al. Aug 2018 A1
20180347680 Akanishi Dec 2018 A1
20180362113 Day Dec 2018 A1
20190017586 Sugimoto Jan 2019 A1
20190085899 Bernardele Mar 2019 A1
20190152558 Staples et al. May 2019 A1
20190185108 Bush et al. Jun 2019 A1
20190210677 O'Reilly Jul 2019 A1
20200200253 Klawer et al. Jun 2020 A1
20200256446 Klawer et al. Aug 2020 A1
20210094652 Staples Apr 2021 A1
20230111794 Lee Apr 2023 A1
Foreign Referenced Citations (36)
Number Date Country
2964058 Oct 2017 CA
1830722 Sep 2006 CN
200999089 Jan 2008 CN
101224782 Jul 2008 CN
103133637 Jun 2013 CN
107380340 Nov 2017 CN
3130258 Jun 1982 DE
3531030 Mar 1987 DE
19751879 May 1999 DE
19954432 May 2001 DE
20218755 Feb 2003 DE
102015005673 Nov 2015 DE
202017107695 Mar 2018 DE
0144984 Apr 1989 EP
0538780 Apr 1993 EP
1270393 Jan 2003 EP
1281609 Feb 2003 EP
1352825 Oct 2003 EP
1426282 Jun 2004 EP
1493654 Jan 2005 EP
1619417 Jan 2006 EP
1884460 Feb 2008 EP
1884461 Feb 2008 EP
2423091 Feb 2012 EP
2600778 Feb 2017 ES
904975 Nov 1945 FR
946276 May 1949 FR
2501615 Apr 1986 FR
2005363 Jun 1982 GB
H10181662 Jul 1998 JP
2005053410 Mar 2005 JP
200821216 May 2008 TW
201530021 Aug 2015 TW
2007147909 Dec 2007 WO
WO 2007147909 Dec 2007 WO
2010136135 Dec 2010 WO
Non-Patent Literature Citations (15)
Entry
Chinese First Action and Search Report, App No. 201710232829.8, 12 Pages, dated Feb. 3, 2020.
European Examination Report, European Patent Application No. 17166123.4, 10 Pages, dated Mar. 18, 2020.
Google Translation of Decision of Rejection for TW Appl. No. 106112061, dated Feb. 26, 2018 (Year: 2018).
Google Translation of Rejection for TW Appl. No. 106112061, dated Jul. 30, 2018 (Year. 2018).
Inverted trapezoid—Google Search, Oct. 4, 2019, (Year: 2019).
Machine Translation of Chinese First Action and Search Report, Appl. No. 201710232829.8, dated Feb. 3, 2020 (Year: 2020).
European Search Report, European Patent Application No. 17166123.4, dated Oct. 5, 2017, 9 Pages.
Decision of Rejection for TW Application No. 106112061 pp. 8, dated Feb. 26, 2018.
Decision of Rejection for TW Application No. 106112061 pp. 10, dated Jul. 30, 2018.
Chinese Second Action and Search Report, App No. 2020011439469.7, 16 Pages, dated Mar. 8, 2022.
Chinese Third Action and Search Report, App No. 2020011439469.7, 7 Pages, dated Aug. 11, 2022.
Chinese Fourth Action and Search Report, App No. 2020011439469.7, 24 Pages, dated Feb. 20, 2023.
Chinese Third Action and Search Report, App No. 2020011439469.7, 7 Pages, dated Aug. 18, 2022.
Proximate definition, Dictionary.com, Sep. 28, 2022 (Year: 2022).
Tang, et al., “Guide for Designers of Plastic Articles”, Sep. 30, 1993, p. 175.
Related Publications (1)
Number Date Country
20210387694 A1 Dec 2021 US
Continuations (4)
Number Date Country
Parent 17067643 Oct 2020 US
Child 17460875 US
Parent 15669756 Aug 2017 US
Child 17067643 US
Parent 14341300 Jul 2014 US
Child 15669756 US
Parent 13675304 Nov 2012 US
Child 14341300 US
Continuation in Parts (1)
Number Date Country
Parent 12432681 Apr 2009 US
Child 13675304 US