Abstract:
A bicycle rim constructed from a fiber reinforcement impregnated with a resinous material to provide stiffness, strength, is light in weight and presents minimal aerodynamic drag. The rim is constructed from two semi-circular rim sections that are each formed from glass, carbon, or boron fibers that are applied at distinctive crossing angles as layers or “plys”, receive an epoxy thermoset resin or a nylon thermoplastic resin, and are cured in a mold cavity. A pair of rim half sections are matched and are coupled together at their ends into a circle by telescoping aligned ends of each of the rim half sections over inner inserts that an epoxy structural adhesive has been applied to, and the joined rim section ends receive a gusset fitted and bonded along the rim half section end junctions, and with the finished rim drilled appropriately. to receive and mount spoke ends.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to bicycle rims and other like rims that are composites manufactured as multiple components that are assembled after molding. 
     2. Prior Art 
     While current light-weight bicycle rim technology encompasses composite rim and wheel construction, most such composite rims are manufactured as a one piece component with no secondary assembly required to complete the rim structure. Where a composite rim has been manufactured as multiple components and assembled after molding, the segmentation of the rim is through the center-line of the “Z” axis as opposed to the “X” or “Y” axis, and such sections have often not been well matched creating a finished rim that is warped or is out of round. Additionally, in practice, current composite rim construction has been based upon a woven reinforcement design and no product is currently available that is marketed as a unidirectional laminate structure. 
     Further, because high pressure is required to sufficiently compact the multiple unidirectional layers, also known as “plys” of unidirectional fibers of the rim structure, a heavy solid shaped mandrel is required to allow for a creation of a pressure thereagainst that is necessary to compact such-multiple layers. The present invention that utilizes a two piece rim that are joined by bonding at their ends, with each rim piece or half section formed on a mandrel capable of expanding under curing heated to create an outwardly directed force on the material laid up on the mandrel surface, compresssing layers against a mold cavity wall. Such a heavy internal pressure creating mandrel is extracted after curing, leaving only the hollow, light-weight rim half section . The molding technique of the invention further deviates from traditional composite molding techniques, such as are used with fiberglass, or carbon fiber, molding techniques due to the high pressure as is required to compact the multi-ply laminate. Where traditional molding techniques required only a maximum of fourteen (14) psi to appropriately mold the laminate, the invention requires a minimum of two hundred fifty (250) psi to sufficiently compact the multiple layers or plys forming the rim of the invention. 
     SUMMARY OF THE INVENTION 
     A bicycle rim, or like rim, is constructed from layers of plys of unidirectional fiber layers to provide a rim that improves upon traditional metal of other composite construction by a decrease in weight, an increased strength and stiffness while providing a profile having low aerodynamic drag characteristics. These rim improvements decrease the time and/or effort required by a cyclist to pedal a given distance, providing for an improvement in acceleration and a decrease in required human power output. This increased efficiency and performance is achieved by a decrease in rim rotational inertia and by a creation of an aerodynamically enhanced shape. The light weight construction and aerodynamically enhanced shaped is achieved through a unique combination of a use of multiple layers of unidirectional reinforcement that is applied at high pressure in a unique molding technique where the rim is formed in two identical hollow hemispherical sections that are joined together at their ends using internal inserts telescoped into the rim section ends ends that are pushed together and bonded therein, and by fitting a V-shaped external gusset over the joined ends, with the internal insets and external gussets each receiving a bonding material, such as a standard two part epoxy structural adhesive, applied thereto prior to fitting the components together, creating a continuous structure. 
     It is an object of the present invention is to provide a fiber reinforced rim that is exceptionally strong and light in weight by a manufacture of separate hollow hemispherical rim sections by an application of layers or plys of unidirectional fibers that are arranged at distinctive crossing angles and within separate planes, that are subjected to heat and high pressure to create identical rim sections for joining at their ends by an adhesive bonding into a rim that is appropriate to carry design static and dynamic loads. 
     Another object of the present invention is to provide a rim to carry anticipated static and dynamic loads by formation of a reinforcement by an application onto a mandrel of multiple plys of unidirection fibers that are arranged in distinctive crossing angles, and within separate planes, onto a removable mandrel and including applications of an epoxy thermoset resin or a nylon thermoplastic resin to the layers of fiber, and maintaining the mandrel and reinforcement at a temperature of approximately two hundred five (205) degrees Celsius for a period of time to cure the reinforcement to form the rim hemispherical sections that are matched, and the matched rim half sections are joined at their ends into a circular rim. 
     Still another object of the present invention is to provide, as separately manufactured items, identical hollow hemospherical rim sections and joining a pair of matched rim sections by telescoping the rim sections ends together over each of a pair of internal insert coated with an adhesive and by bonding a V-shaped gusset over each of the butting ends joint. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will become more apparent from the following description in which the invention is described in detail in conjunction with the accompanying drawings: 
     FIG. 1 is a profile view of a cross section of a rim of the invention; 
     FIG. 2 is a profile view of a quarter section of a bicycle wheel showing a hub with spokes radiating radially outwardly therefrom that connect, at spaced interval, into the rim of FIG. 1 that rim has been drilled to receive which spokes; 
     FIG. 3 is a side elevation of a bicycle wheel that includes the rim of FIG. 1 shown formed in two hemispherical sections that are joined together at their ends, with a gusset shown placed over the outside of the rim at the joined ends; 
     FIG. 4 is a side elevation perspective view of a full half section of the rim of FIG. 1, showing a section of the rim half section aligned for fitting over an inner insert fitted into an end of another rim half section and showing an exterior gusset fitted onto one of the rim half sections for coupling the rim half sections together at their ends, forming the rim of FIG. 3; 
     FIG. 5 shows a profile cross sectional view of the rim of FIG. 1 being formed on a mandrel that includes a core covered by a silicone material, illustrating a preferred mandrel whereover the rim half section is formed; 
     FIG. 6 shows a profile cross sectional view of a mold containing the rim half section and mandrel of FIG. 5; 
     FIG. 7 is a top plan view of the mold containing the rim half section and mandrel of FIG. 6; 
     FIG. 8 is a side elevation perspective view showing the telescoping together of the rim half sections ends over inner inserts and showing gussets fitted across the butting rim half section ends to assemble the rim of the invention: 
     FIG. 9 shows a side elevation perspective view taken from ahead of the gusset showing the gusset as a flat circle that is bent across is mid-section or axis a into a V shape; 
     FIG. 10 shows a side elevation perspective view taken from a ahead of a continuous inner insert showing a first embodiment of an inner insert for joining rim half sections together; 
     FIG. 11 shows a side elevation perspective view taken from ahead showing side walls of a non-continuous second embodiment of an inner insert for joining rim half sections together; 
     FIG. 12 shows the inner insert spaced side walls of FIG. 11 as having received a foam core fitted therebetween; and 
     FIG. 13 shows a side elevation view of the rim half sections ends fitted over the inner inserts, shown in broken lines, with the V-shaped shown gussets aligned for fitting onto the joined rim ends at the rim inner circumference. 
    
    
     DETAILED DESCRIPTION 
     The invention is hereinafter described with reference to a bicycle rim that is included in a bicycle wheel. Though, it should be understood, the invention is not necessarily limited to bicycle rims and wheels and could be utilized with other like rim and wheel arrangements and, of course, is suitable for manufacture of any appropriate size of bicycle rim. Accordingly, while a preferred embodiment of the invention is herein shown, the invention is applicable to a number and variety of rim and wheel configurations within the scope of this disclosure. 
     FIG. 1 shows a profile cross section of a rim half section  11  of the invention that is a component of a bicycle wheel  10 , as shown in FIGS. 2 and 3. The rim half section  11  is shown in FIGS. 1,  4 ,  5 ,  6 ,  8  and  10 , as having a thin side wall that may, or may not, be of a uniform thickness. In fact, the rim wall thickness may vary depending upon the section of the rim as is being formed, providing that identical halves of the rim half section on opposite sides of a center vertical axis therethrough are identical. 
     To form the rim half section  11 , multiple layers or “plys” of unidirectional fibers, preferably, carbon fibers, though glass, boron, or the like, are arranged in layers at distinctive crossing angles, and in separate planes, to create a structure that is appropriate to carry the anticipated static and dynamic loads of a rim for any given size, model or type of bicycle. This reinforcement is the first and primary constituent of the structure and occupies approximately seventy two (72) per cent by volume. An epoxy thermoset resin or a nylon thermoplastic resin is used to coat the layers or plys as they are laid up and function as the secondary constituent of the structure and will occupy approximately twenty eight (28) per cent by volume. The coated layers or plys are to be heated in a mold temperature of approximately two hundred five (205) degrees Celsius to cause a sufficient flow of the resin to properly bond together the unidirectional fibers of the reinforcement. 
     In practice, to form rim half section  11 , layers or plys of the reinforcement are saturated with the appropriate amount of uncured resin and are laid up in layers upon a rigid appropriately shaped mandrel  13 , and one such mandrel is shown in a cross section view of FIG. 5 that is appropriate for practicing the invention. Shown in FIG. 5, the mandrel  13  core  14  is preferrably constructed from two thousand (2000) or six thousand (6000) series aluminum that is coated with pourable Room Temperature Vulcanizing (RTV) silicone  15 . Mandrel  13 , after being surrounded by resin coated layers or plys of the reinforcement is placed into a rigid mold  16 , as shown in FIGS. 6 and 7, and best in FIG. 6, that consists of opposing metal plates  17   a  and  17   b  that each have a half circular cavity  18   a  and  18   b , respectively, formed therein that the mandrel  13  coated with the layers or plys of resin coated reinforcement is place in With the mold  16  metal plates  17   a  and  17   b  contained in a metal ring  19 . The mold cavities  18   a  and  18   b  together have a molding surface that is identical to that of the finished surface of the cured rim half section  11 . So arranged, the mandrel plates  17   a  and  17   b  are held or pressed tightly together, as illustrated by arrows A. Heat is applied through the mold to approximately two hundred five (205) degrees Celsius, but which heat may be in a range of from ninety (90) to three hundred (300) degrees Celsius for a period of approximately forty five (45) minutes, but which applied heat for a period of time is proportional with a straight line graph having end points at ninety (90) degrees Celsius for two hundred (200) minutes and at three hundred (300) degrees for fifteen (15) minutes setting out the relationship of heat to time to provide a successful rim half section compression and curing, within the scope of this invention. The heat acts as a catalyst in the reaction of the resinous material providing a curing of the reinforcement. Heat transmitted through the mold not only cures the resin, it also creates an expansion in the dimensions of the aluminum and silicone mandrel resulting in the compaction of the multiple layers of plys of reinforcement from the inside out, compressing the reinforcement against the metal mold cavity  18   a  and  18   b  walls. In this process a pressure of preferably two hundred fifty (250) psi is exerted into the reinforcement, but which pressure may be from two hundred twenty (220) to fofur hundred (400) psi within the scope of this disclosure, to adequately compact the reinforcement fiber and resin together during the curing process. 
     Upon completion of the cure cycle the mold  16  containing the cured rim half section  11  and mandrel  13  is opened and the rim half section containing the mandrel  13  is removed. Thereafter, the half rim section  11  and mandrel  13  are placed into a freezer that is maintained at approximately zero degrees Celsius. During cooling, the mandrel  13  experiences contraction of the aluminum core  14  and silicone  15  and separates from the rim half section  11  compacted layers or plys providing a separation that allows the rim half section  11  to be removed from the mandrel. The mandrel  13  can then be reconditioned for use in forming another rim half section thereon. 
     After completion of the cure of two rim half sections  11  and  12 , respectively, the one half rim is matched with the other half rim to provide, when completed as the circular rim, as shown in FIGS. 3 and 13, a rim that is essentially a perfect circle and is not warped. The two rim half sections  11  and  12 , respectfully, are joined by fitting an internal insert  21  or  22 , shown in FIGS. 4 and 8, coated with an adhesive, into one half section  11  end and  11   a  and passing an end  12   a  of half section  12  thereover until which ends  11   a  and  12   a  butt together. Examples of internal inserts  21  and  22  are shown in FIGS. 10,  11  and  12 , respectively, and can be constructed from any number of materials, including composites and/or metal. Examples of two internal inserts  21  and  22  are shown, through, it should be understood, the invention is not limited to any one particular insert or insert configuration, and that the internal inserts  21  and  22  are shown herein as examples only. 
     Internal insert  21 , shown in FIGS. 11 and 12, is non-continuous and is formed in two side sections that are arranged as mirror images to one another and each is shaped to essentially conform to each of the inner surface of the rim half section walls. The internal insert  21  is formed by attaching the halves opposing faces, as shown in FIG. 12, to a section  23  of a foam, as shown, or to any other type of semi-structural material to include: balsa wood, honeycomb, a syntactic filler, or the like. The finished internal insert  21  having a shape and dimensions to fit snugly into the ends  11   a  and  12   a  of the rim half sections  11  and  12 . After coating with an adhesive, that is preferably any standard two part epoxy structural adhesive, the rim half section ends  11   a  and  12   a  are slid over the internal insert  21 , as shown in FIGS. 4 and 13, connecting the rim half sections, forming the rim  20 . 
     Alternatively, the continuous internal insert  22  can be used, as shown in FIG. 8, for joining the rim half sections  11  and  12  ends  11   a  and  12   a  together. The internal insert, shown in FIG. 10, is formed as a thin walled continuous section of a metal, composite, or other appropriate material, to have a shape and dimensions to fit snugly into the rim half sections ends  11   a  and  12   a . With, in practice, like the internal insert  21 , the internal insert  22  is coated with an adhesive, that is preferably any standard two part epoxy structure adhesive, prior to fitting the two rim half section ends  11   a  and  12   a  together, as shown in FIG.  8 . 
     After fitting and securing the rim half sections  11  and  12  together at their butting ends  11   a  and  12   a , a gusset  24 , shown best in FIG. 3, is installed to the rim inner circumference, extending partially around the junction of the rim half section ends  11   a  and  12   a , as shown in FIGS. 3,  4 ,  8  and  13 . The gusset  24 , as shown, is preferably formed as a thin disk of an appropriate material such as a metal, composite, or the like, and is bent across a mid-section or axis  24   a  thereof into a V-shape. The V-shape is such that the area between the V sides will approximate, to fit snugly against, the rim  20  inner circumference and over the rim  20  lower sides at the junctions of the rim half section ends  11   a  and  12   a . The gusset  24  also receives a coating of an adhesive over its inner surface, such as a standard two part epoxy structure adhesive as is used to coat the internal insert  21  or  22 , for permanently securing the gussets across the connection of the rim half sections  11  and  12  at their ends  11   a  and  12   a , completing the rim  20 . 
     The rim  20  can then be drilled at spaced internals around the rim  20  longitudinal center line, shown at  25  in FIGS. 2 and 4, to receive spoke rim ends  26   a  fitted therethrough and connected in spoke attachments  27  that are fitted through outer rim holes, not shown, and are maintained in the rim  20 , as shown best in FIG.  2 . The spoke  26  spoke hub ends  26   b  are secured to a hub  28 , as shown in FIGS. 2 and 3, completing a bicycle wheel  20 . 
     Hereinabove has been set out a description of a preferred rim of the invention that is formed by connecting separately formed rim half sections at their ends, along with embodiments of internal inserts for use in making which end connection, and gusset components for reinforcing the rim at the rim half section ends joints. It should, however, be understood that the present invention can be varied within the scope of this disclosure without departing from the subject matter coming within the scope of the following claims, and a reasonable equivalency thereof, which claims I regard as my invention.