GB2502468A

GB2502468A - Modular hollow bamboo bicycle frame.

Info

Publication number: GB2502468A
Application number: GB1314539.6A
Authority: GB
Inventors: Thomas Henry Williams
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-08-14
Filing date: 2013-08-14
Publication date: 2013-11-27
Also published as: GB201314539D0

Abstract

A hollow bicycle frame is constructed from pre-cured composite sandwich laminates formed from bamboo or other ligneous material and woven fibrous fabric. The design makes use of generally flat veneer raw material. The performance of the bicycle frame can be altered indefinitely by alterations of said woven fibre composite materials used in the individual sub-assembly parts. The current invention is optimised for the use of more sustainable materials such as bamboo to encourage a more sustainable bicycle frame product.

Description

Title: Manufacturing method & modular construction of a hollow non-tubular bamboo bicycle frame.

BACKGROUND:

The bicycle has been used as a method of transport for years and the design and manufacturing of the bicycle has arguably maintained true to a conventional metallic structure formed to provide requirements of being strong, lightweight, economic and protect from environmental exposure. Materials used range from metals through to carbon composite and more recently adoption of more eco friendly alternatives such as bamboo. The development of bicycle construction technologies have generally revolved around the same fundamental design of tubular members or more recently performance surfaces to achieve better aerodynamically performing products. However as a consequence this can relate to high production costs, complex machining for tools and use of expensive materials to achieves the desired performance characteristics. With ever more pressure on reducing costs and awareness of sustainable materials and design of bikes has seen an introduction of bamboo materials un-modified from their original tubular shape to replace existing frame construction methods, relying on their natural mechanical properties to match design requirements of a bicycle.

Bamboo has been the material of choice due to its good compressive, tensile and hardness mechanical properties alongside its sustainability and ease of processing that lends to great economic and social benefits when replicated into an everyday product. However at present the bamboo used in bicycles has been little modified from its natural hollow form to directly replace tubular members with only minor alterations to joint interfaces and surface treatments to protect from the environment. By using a different raw form of bamboo or other ligneous wood type materials in the form of veneer has lent itself to a different type of bicycle construction and thus design, which hopes to improve mass production efficiency, provide a more sustainable, aesthetically pleasing and distinct design as a consequence of the new manufacturing techniques implemented and materials chosen.

STATEMENT OF INVENTION:

For the deficiencies of the prior art, the present invention is provided a method of construction and thus manufacturing technique of a generally hollow non-tubular bicycle frame constructed of bamboo or other ligneous materials. The frame is constructed in a manor that multiple laminate pieces are firstly constructed to create sub assemblies before a modular jigsaw style type of construction where all parts are fused together to generate a complete bicycle frame that is not of a conventional tubular design. The present invention makes use of bamboo or other ligneous types of material in a veneer or similar geometric raw form before then being cut to the required modular part shape.

The addition of multiple parts to create one modular sub-assembly can be altered to create different mechanical and thus performance properties of that individual piece. A common laminate consisting of a sandwich composite comprising of bamboo and other fiber reinforced woven fabrics such as but not limited to GFRP, Carbon, Keviar or Flax. Epoxy resin systems are then used as the adhesive system to establish a reaction to fuse the individual sub assemblies together) making use of pre-pregnated or wet systems. The process lends itself to common composite manufacturing techniques such as but not limited to compression molding, vacuum bagging, resin infusion and resin transfer molding. To improve the mechanical properties but also protect the raw bamboo or ligneous materials on the outmost surface from environmental elements a Polybatylene terephthalate (PAT) or other similar plastic sheet layer is used. The sheet is inserted into the molding technique to improve production efficiency, generate better mechanical properties, improve environmental protective barriers and allow for use of digital printing or sublimation of graphics prior to individual sub assembly mokiing processes. The use of other PU based of ABS materials can be inserted around the perimeter of the individual sub-assembly sidewafls to protect the finished product from use and also from environmental exposure.

Individual parts of the frames outer shell are constructed to generate performance specific sub assemblies of which can then be assembled into a complete bicycle frame. Sub assemblies of the bicycle frame include the mainframe side and inner wails, chain stays, seat stays, head tube fixture) bottom bracket fixture and seat tube fixture. The manufacturing of the sub-assembly fixtures in the head: tube, bottom bracket and seat tube provide the main supporting structure and location positions for assembly of the entire frame.

These sub-assemblies raw stock material is constructed prior to machining into the desired thickness out of pre-laminated blocks of bamboo in various geometrically orientated directions such as those available from MOSO bamboo products or by manually laminating bamboo veneers in a sandwich using mechanically advantageous woven fabrics between layers to a achieve a specific thickness.

In the present invention the pre-cured sub-assemblies are then tooled into position with head tube, bottom bracket and seat tube fixture sub-assemblies providing locations for the side and inner wall surfaces to adhere. Complete assembly of the frame will consist of bringing sub-assernbhes together for a jigsaw style construction to create a bicycle frame that is mostDy hollow. By adjusting sandwich laminates in the sub-assembly parts the performance of the frame can be altered.

Advantages of the present invention means a frame that is fundamentally different in construction that will enable a simpler manufacturing process, provide tuning of individual frame parts by defining specific composite sandwich laminates and simpler tooling. The type of construction, assembly process, bike construction and design lends itself to a more customizable modular approach; avoiding complex 31) surfaces and thus avoiding the costs these occur in tool making and machining. The inherent generally hollow construction, alongside the assembly process and pre-cured sub-assembly parts lends itself to the easy installadon and operation of any electronic motors and auxiliaiy equipment that can be installed into the frame prior to complete assembly. The construction also allows the use of different hgneous materials, predomnnateiy bamboo as it provides great strength to weight ratio as well as being sustainable in design with good absorption of vibration. Using multiple laminates built up into a thickness or a stock block to build up the headset bottom bracket and seat post fixtures enables a construction that uses more bamboo throughout the bike; as well as being advantageous as the said fixtures act as a tool for location of further sub-assembly parts.

The present invention provides an eco friendly but performance orientated bicycle frame that Is less expensive to construct as less tooling is needed, bamboo is widely sustainable, fmishing is minimized due to application of top sheet technology, performance can be tweaked dependent on sub assembly construction, size of frame modified without the need for new molds for each size frame and machining complexity is reduced due to the use of stock veneer and stacked laminates to create sub-assembly bicycle frame parts. Further, the flexibility of different sub-assembly composite constructions using the same bicycle tooling can provide different grade of performance bike which further increases manufacturing costs but also provides a large range of bicycle performance options and aesthetic finishes for the customer.

All of the parts, uses, and advantages of the current invention will become apparent in the detailed description and the drawings in which numbered

drawings parts are referred in the description.

DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: Figure 1 comprising of Figure 1A, lB. 1C and 1D are simplified left side, right side, rear perspective and front perspective drawings of the bicycle complete frame operative in accordance with an embodiment of the present invention; Figure 2 comprising Figure 2A. ZB and ZC are simplified side and perspective view drawings of head tube, seat post and bottom bracket fixtures in accordance with an embodiment of the present invention; Figure 3 comprising Figure 3A, 3B, 3C, 3D and 3E are simplified drawings of die parts that make up the side wall assemblies of the frame and include part side views, assembled perspective and side view.

Figure 4 comprising Figure 4A and 48 are simplified side and perspective drawings of the inner and outer frame wall assemblies; and Figure 4C is a simplified drawings of an Inner or outer frame part.

Figure 5 comprising Figure SA and SB are simplified side view drawings of the chain stay and seat stay assemblies; Figure SC and SD are simplified construction drawings; and Figure SE is a simplified side view drawing of the tooling procedure to create the chain stay and seat stay operative in accordance with an embodiment of the present invention.

Figure 6 comprising Figure 6A, 68, 6C are simplified drawings of the bamboo or ligneous raw rnateriai used; Figure 61) the orientation of said raw material in an embodiment of the present invention; and Figure 6E an embodiment of the type of nesting procedure to cut assembly parts out of the raw bamhoo/iigneous materiaL Figure 7 comprising Figure 7A is a simplified construction drawing of an embodiment of the present invention; and Figure 78, 7C and 7D are simplified cross-sectional drawings showing the interlocking of frame walls to complete a hollow non-tubular frame shape operative in accordance with an embodiment of the present invention.

Figure 8 comprising FigLire BA, 88, BC and 3D are simplifIed tooling drawings for the build of individual modular sub-assemblies and the full frame assembly operative in accordance with an embodiment of the present invention.

Figure 9 comprising Figure 9A, 98 and YC are simplified exploded drawings of the frame modular construction detailing the assembly of fixture and side wall suh-assembiies in accordance with an embodiment of the present invention.

Figure 10 comprising Figure IOA and lOB are exploded and side view assembly drawings of the inner and outer frame sub-assemblies; and Figure lOB a simplified drawing of the complete frame without chain stays or scat stays in accordancevith an embodiment of the present invention.

Figure ii comprising Figure hA is a simp]ified drawing showing the addition of the standard metallic items to accept standardised bicycle components to the frame; and Figure 1 lB and tiC are simplified perspective drawings of the assembly of the chain stay and seat stay sub-assembly parts to complete an embodiment of the present invention.

DETAILED DESCRIPTION

The following detailed description will make use of a reference of 100 depicting the mainframe assembly construction and will embody all further sub- assemblies and parts within this. The reference of 200 embodies the sub-assemblies making up the chain stay and rear stays, which are assembled upon the main frame.

Reference is now made to Figure lA-iD, which illustrates a bicycle frame 100 and the rear stays 200 in which they are constructed and operative in accordance with a non-limiting embodiment of the present invention. Figure 1A shows the side view of the main bicycle frame 100 and consequently further parts that build up this complete assembly. The left side of the frame is made up of a sub-assembly parts lOla, lOib and lOic; these form the frames side wall and in this embodiment are of individual parts jointed together in an embodiment such that a curved feature is formed at the joining locations. The

S

right side of the frame 100 as shown in Figure lB includes the same sub-assembly parts 102a, 102b and 102c, which make up the right side wall of the frame 100. The right and left side of the bicycle frames 100 side walls are characterized as complete sub-assemblies 101 and 102 throughout the drawings.

The left and right seat stays depicted as 201a and 201b; and the right and left chain stays are depicted as 202a and 202b respectively. The frame 100 is comprised of inner and outer sub-assemblies depicted by 106a-106f of which fit into the internal cavity between the left and right frame side sub-assemblies 101 & 102 and onto the sub-assembly fixtures 103, 104 and 105. The sub-assembly fixtures are depicted as the head tube fixture 103, seat tube fixture 104 and bottom bracket fixture 105. The frame 100 is depicted with the addition of metallic parts that are inserted into the frame 100 such that standard bicycle components for example handle bars, seat posts, bottom bracket cups, rear and front wheel hubs and other types of bicycle auxiliary components can be fitted.

The metallic parts are shown as simplified drawings throughout and are referenced as seat post tube 107, bottom bracket tube 108 and head tube 118.

In the illustrated embodiment sub-assembly fixtures depicted as 103, 104 & 105 can be seen in Figure 2A-2C and show their side and perspective view. These fixtures makeup the internal layer of the current invention and provide a fixture for the addition of subsequent sub-assembly parts to adhere to. The said fixtures are comprised of bamboo or other ligneous materials and in this embodiment of the current design are manufactured out of stock bamboo ply that is sourced from a supplier in a post processed form such that only minor modifications to thickness need to be address dependent upon design specification. Figure 6C shows a simplified illustration of the form of the said stock bamboo ply 111 that is used to manufacture the said fixtures. The use of this stock material gives an advantage to the design in that manufacturing stages are minimized as a product exists that can be optimized for this current invention, minimal finishing is required to provide aesthetically pleasing results and the integrity of the product is known as it is post processed and not in the form of a raw material. The dimensions, ply orientation and finishes of this said post process bamboo ply is non-limiting to this current invention and thus can be optimized in future embodiments to become thicker, stronger, more aesthetically pleasing etc depending upon design specifications. With reference to the simplified illustrations in Figure 2A-2C the shape of the fixtures exists in a design that is proposed to be easier, cheaper and quicker to machine by lending itself to simpler 2 1/2D machining and lends itself away from complex surface machining, however this does not limit the design and thus to adhere to a more complicated design brief these said fixtures exist with the possibility of more complex surface machining to be applied.

The nature of these said fixtures is that they are machined to enable the direct interaction of the sidewall sub-assemblies 101 and 102; inner and outer sub-assemblies 106a-106f. The said fixtures are advantageous in the way the main frame 100 is modularly assembled together, making use of these fixtures as tooling aids to locate and align assemblies 101, 102 & 106. This allows for the present invention to become more economical and easier to mass-produce, lending itself to reduced tooling costs and simplified assembly processes. Figure 3D illustrates the use of the fixtures as tooling to locate and position the said assemblies 101 & 102, this is a direct advantage of this current invention compared to other bicycle assembly procedures, allows for a range of different tooling and fixtures to be used that can reduce manufacturing costs and provide a more sustainable frame 100 design.

Further to the above the fixtures exist in the areas of the bicycle frame 100 in which the most strength is required and are common areas on a bicycle frame for addition of standardized components to fit upon the main frame such as forks, cranks, seat posts etc. The addition of these additional standard bicycle components require fitment into the said frame 100 in the form of metallic components as stated above. The said fixtures allow for the addition of these parts with the use of an epoxy resin system or other similar adhesives to provide the bonding of metallic to bamboo, to increase the bond fillers such as glass, carbon, metallic or other similar material maybe be added in fiber or dust form to provide the strength set out in the design requirements.

With reference to the left and right side sub-assemblies 101 and 102 in the illustrated embodiment in Figure 1A-1D these assemblies are constructed out of bamboo or other ligneous type materials and exist to form the left and right side of the said bicycle frame 100. Said sub-assemblies are constructed in a sandwich laminate technology wherein they are built up of one or more layers of bamboo veneer material. The outside layer of the 101 & 102 in this present design embodiment exists with three separate veneer bamboo parts comprised of lOla, lOib and lOlc; similarly 102a, 102b, 102c; however the present invention is not limited to the current design specification and can exist with one or multiple parts to form the outside layer of the sub-assemblies 101 & 102.

The type of raw bamboo material used in the current invention is of a veneer 1-ply construction, the bamboo material is common as a post processed product and widely available in standardized sheet sizes most commonly 2440mm x 1220mm and available in various thicknesses ranging from 0.6mm veneer up to 5-6mm veneer 1-ply. The present invention makes use of a range of thicknesses of veneer bamboo in 1-ply form, Figure 6A illustrates the most common form of bamboo 1-ply veneer available, all of which dependent on design requirements are relevant for use in this current invention and are unique to this design of a frame 100. Simplified illustrations llOa, llOb, and hOc show plain pressed, side pressed and density forms of the natural bamboo material that are available at present in the post processed 1-ply veneer. Figure 6B shows a simplified illustrative perspective view of this type of veneer, detailing the thickness properties of which are variable dependent on supplier and can be specified depending on the design requirements of this present invention. The thickness of type of chosen bamboo veneer is dependent on the design and specific to the current invention as it depicts the properties in terms of performance of the said frame 100. Plain pressed bamboo llOa is preferable in thinner veneer laminates due to the structural integrity of the sheet whilst handling in a production environment, all laminates provide an aesthetically pleasing look which is unique to this current invention, all laminates can provide particular mechanical properties and dependent on orientation determined by design brief will allow for different performing bicycle frames 100. The current invention makes use of these varying mechanical and aesthetic properties of bamboo to differentiate the current invention in terms of raw material type used; differentiating itself from present inventions relating to the use of tubular bamboo to create a bicycle frame; and also to establish a sustainable aspect to the current invention by using a bamboo. However; the construction technique is thus non-limiting in terms of type of ligneous material used and can exist with the use of other 1-ply or similar sheet post processed raw materials depending on design requirements of the frame 100.

With reference to the illustration as seen in Figure 6E, it can be seen that the current invention is unique in that it uses post processed raw 1-ply veneer to formulate the parts of sub-assemblies in the current invention. The said simplified illustrations depict the nesting of such sub-assembly parts that are to be machined out of the same sheet of material. The type of sandwich construction of the frames sub-assembly parts lends itself in the current invention to an economical alternative to present bicycle manufacture. Nesting the said pieces to maximize sheet usage and minimize waste is key in the manufacture of the parts to create the said sub assembly parts. In the simplified illustrations parts lOla-bid, 102a-102d & 203 are nested with the purpose of grain orientation in the said bamboo veneer running longitudinally along the length of the said parts; this flexibility in orientation is unique to the current invention and is optimized dependent on the design requirements of the chosen frame 100. All parts excluding the said fixtures 103, 104 and 105 are created using this method of machining out of the said veneer 1-ply sheet; something that is unique to this design and has advantages in a mass production environment. The type of machining that is envisaged for the said parts allows laser cutting, water cutting or CNC machining; the chosen machining method is likely to be dependent on cost and production quantities but the flexibility of choice lends itself to a more cost effective manufacturing process opposed to other manufacturing methods seen in the field of bicycle manufacture. Figure 6D illustrates the outside veneer parts that make up sub-assembly 101; it can be seen that the orientation of fibers has been altered in different planes and this will be dependent upon design requirements; orientation in this current invention is non-limiting to future designs.

To further illustrate the interaction of the said veneer parts into a sandwich construction Figure 3A-3E depicts the typical construction. Figure 3A & 3B illustrates the parts lOla-lOlc as they join to form the outside laminate of the sub-assembly sidewall 101. In the present invention this said sidewall comprises of three parts that form a unique and distinctive joint between said pieces; however dependent upon design this outside veneer section can be made up of one or more parts. Figure 3C illustrates the internal structure of the said sandwich construction, made out of the said bamboo veneer 1-ply laminate or other ligneous types of material it provides the secondary material to the outside layer in which a third composite fiber fabric material and epoxy resin system is between. Figure 3D shows a simplified illustration of the type of interaction of the two said inner and outer pieces and thus provides a unique interaction of a frame sidewall as present in the current invention. The design for the profile of the inner part lOld & 102d is offset from the outer profile part lOla-lOic thus creating a surface area where said sub-assembly parts 106 can interact to provide a solid joint during final assemb'y of all sub-assemblies. Figure 4A & 4B illustrate the interaction of the said parts 106a-1061 onto the fixtures 103, 104 & 105; the interaction and thus design allows for a direct perpendicular fitment between parts during assembly and design provides adequate surface area of the joints to allow adhesion and sufficient strength for the current invention.

The sub-assemblies 101 & 102 not only provide this locator for a joint for assemblies 106 but also provide a surface required for the interaction of said sidewalls to the fixtures 103, 104 and 105.

The inner and outer sub-assembly parts that are required for completing the frame 100 once the side sub-assemblies 101 & 102 are in located are formed out of the same veneer bamboo i-ply sheet llOa-llOc common to all parts excluding the fixtures 104,105 & 106. In the current invention the inner parts 106c-106f are formed out of flat sections of i-ply veneer, with their thickness and type of veneer determined by design requirements. The assembly locations of parts 106c-106f is shown in Figure 4, the design allows for the interaction of said flat sections to minimize manufacturing complexity, increase manufacturing time, reduce tooling costs and lends itself to a simpler frame assembly and reducing the bending of said veneer around complex curves. Part 106a & 106b in the current invention is depicted as a curved section, thus this lends itself to be pre-cured in this form prior to assembly to complete frame 100. Figure BB and SC illustrate the use of tooling to produce this type of pre-curved part that is required for 106a & 106b; 117 is depicted as the tooling. This tooling is provided to create the formed feature required and in a manufacturing environment is likely to be made from a composite, meta' or similar tooling material.

With reference to the frame sub-assembly sandwich laminates and thus the tooling methods to produce the said laminates Figure BA depicts a unique advantage to the current design as one embodiment of allowable tooling for the chosen frame sub-assembly parts. Due to the inherent nature of the sub-assembly parts being made of i-ply veneer bamboo in a sheet raw material form, the assemblies 101, 102 & 106 in this current invention are of a flat nature once in a sandwich layered construction. Figure BA illustrates how assemblies 101, 102 and 106c-f can be tooled up on a flat surface that is parallel to the main surface area of the parts mentioned. The type of molding technique required for the laminating of such parts is of common compressive molding technologies wherein force is applied to compress the layers together. In the current invention the parts allow for a compressive molding technique of vacuum, pneumatic, electronic actuated or similar. It has been said the tooling can be in the simplest form a flat table with the use of vacuum bag; this is unique in this current invention allowing for economical and effective molding of multiple sub-assembly parts in one process; further reducing complexity and increasing efficiency in a mass production environment. However not limited to the present invention and depending on performance requirements of the said sub-assemblies more advanced molding techniques and thus tooling is likely to be required; envisaging the use of metallic tooling to increase performance and aesthetics properties of said parts.

The laminate construction within the current invention relates to a sandwich technology that makes use of sustainable materials where possible; such as bamboo, and alongside this incorporates the use of performance woven fiber fabrics determined by design requirements in different design embodiments.

Figure 7A illustrates an embodiment of the construction sandwich that is used throughout the design of the current invention, as stated prior the use of bamboo provide the outer layers of the said laminate, the fiber woven fabric 112 used between these surface interfaces depending on embodiment of the present invention can be of a carbon, glass fiber, flax fiber or other similar composite material. The number of layers chosen and orientation of these woven fabric fibers depends greatly upon the design requirements of the current invention.

The typical laminate will make use of bi-axial, uni-directional, plain twill, tn-ax or other common fabric weaves; the orientation dependent upon mechanical properties of each component within the sandwich laminate. The current invention allows for various different embodiments of laminate processes making use of wet lay up or pre-pregnated technologies to provide the adhesive medium of an epoxy resin system. Epoxy resin systems for the current invention will be optimized for the manufacturing environment and performance properties of an embodiment of the design. The advantages of the current invention allows for pre-pregnated fabric as an optimal choice for a mass production environment allowing for the laser cutting of the fabric nested in the same fashion as in Figure 6E.

During curing of the said sub-assemblies the optimal heat, pressure and compression molding technique will be implemented for the chosen embodiment of the frame design 100. The use of flax woven fabric is optimal in a bicycle frame embodiment that allows for the most sustainable design, in the current invention carbon fiber is chosen which provides for the structural stiffening of the frame 100, whilst keeping a high strength to weight ratio overall. Combing bamboo with carbon fiber as in the current invention allows for many advantages, bamboo providing a naturally strong material in tension with known dampening properties to absorb shock loading whilst riding; carbon fiber providing the high strength to weight ratio required of modern frames along with the optimal stiffness dependent on orientation of fibers.

A unique addition of a top sheet material 113 that is placed in the laminate on the top surface of the sandwich construction can be seen in Figure 7. In an embodiment of the current invention the top sheet material is a Polyhutylene terephthalate [PBT) or other plastic based top sheet material. The material is placed on the outermost surface of the mold and not only provides a barrier from the elements once cured onto the parts hut can he used as a medium for graphical detailing. A top sheet material on the current invention is unique and can allow for less finishing of the parts in a mass production environment. The top sheet allows of different print mediums such as sublimation, direct digital printing, water stickers and others. In other embodiments of the current design however it is possinEe to produce the parts and thus frame 100 without a top sheet and protecting it from its working environment by spraying a gel coat, epoxy coat, PU coal, UV coal, acrylic coal or other wood finishing product.

With reference to the hollow non-tubular design that is unique in the current invention of the frame 100, Figure 7B-7D illustrate the interaction of the sub-assemblies that interact between section X-X, shown in Figure 1A, together to form these hollow sections between the said fixtures 103, 104 and 105. Figure 7B depict the current invention in an embodiment wherein the sidewalls 101 & 102 of the frame 100 are made up of their sandwich laminate as depicted in Figure 7A; these said sidewalls interact with the inner and outer sub-assemblies 106a & 106b. All sub-assemblies in the present invention include the embodiment of the sandwich laminate composite as shown in Figure 7A. The non-tubular design is achieved when these said sub-assemblies interact together in Figure 7C to form perpendicular joints wherein each sub-assembly interacts.

To achieve this assembly of sub-assembly parts they will be again cured using an epoxy resin system, heat, fixtures, jigs and a compressional molding technique to maintain alignment and performance of the said joints. Once these parts a cured in a hollow non-tubular form the edges of the current invention can be rounded with a fillet or chamfered to allow for a more aesthetically pleasing look.

In this current invention the sub-assembly parts of 201 & 202 are laminated in a construction using the same fundamental constructions a depicted in Figure 7A.

Figure SC details an embodiment of the current design of stay for both 201 & 202 wherein one or more veneer 1-ply outline of the stay 203 is the outer layer in a composite comprising the same woven fiber fabric as previously mentioned and depicted as 112. In the current invention the design for the stays are curved, thus requiring tooling to create this formed shape; tools 206 that can be made of metallic, composite or other tooling materials are used as a medium to provide compressive force in the curing of the laminate. Epoxy resin systems, be it pre-pregnated or wet laminate are able to be used in this or other embodiments of the stays depending on performance and design requirements. The orientation of fibers in 201 and 202 again is dependent on performance and design requirements and can be altered in various embodiments of the current design.

The interaction of the rear stays 201 and 202 interact with the frame 100 in this current invention by being fixed in their desired position by the use of an epoxy resin adhesive and a structural joint depending on embodiment of the current design. The stays in an embodiment will fit into the seat post fixture 104 and bottom bracket fixture 105 within a machined location, the location of the fitment is likely to be achieved by CNC machining the desired joint for interaction. To join the stays to accept a hub and thus axle for the rear wheel of the bicycle a metallic component 109 interacts and fits the stays by way of fastener in the form of a bolt, nut etc. It is also possible in another embodiment to include part 109 within the sandwich construction and within the tooling 206 to increase the strength and interaction of said parts. An advantage of the current invention having a part 109 that is removable from the stays 201 & 202 means the use of a belt drive can be implemented into the current invention, which also lends itself to a belt drive system for potential electrical drive applications.

With reference to Figure 9 -11, the exploded perspective illustrations depict an embodiment of a typical and unique construction of the current invention. A simplified inside to outside part listing of the overall frame assembly will now be listed below in accordance with an embodiment of the current invention.

1. Figure 9A depicts parts 103,104 & 105 as the first modules of the assembly process, as being fixture style parts they are responsible for the location of future sub-assemblies and as said can be used as tooling for the next stages in modular assembly.

2. Figure YB depicts the prior said parts and the addition of parts lOld & 102d as the next layer in the assembly construction.

3. Figure 9C depicts the prior said parts and the addition of parts lOla-c & 102a-c as the next layer in the assembly.

4. Figure 1OA depicts parts prior said parts and the addition of parts 106a-f.

5. Figure 1OA depicts a side view of the prior said parts.

6. Figure 1OC depicts a rear perspective view of the main frame 100 of the bicycle.

7. Figure hA depicts a rear perspective view of the main frame and all prior said parts, with the addition of the parts 107, 108 & 118.

8. Figure fiB depicts a rear perspective view of the mainframe and parts 201a-b, 202a-b & 109 in an exploded illustration.

9. Figure 11C depicts a rear perspective view of the mainframe 100 and the rear stays 200 attached in a complete bicycle frame as an embodiment of the current invention.

In addition the construction in the current invention and the modular assembly nature of parts with a laminate sandwich construction as a results exhibits distinctive stripes along the joins of the sub-assemblies. These distinctive visible composites run along joint interfaces and are also left showing when sandwich laminates cross-sections are visible from the outside. The use of different woven fiber fabric in replace for 112 will further differentiate the aesthetics of further embodiments of the current design.

The nature of the frame construction and the said modular assembly process enables a foreseeable implementation of electronic drive; allowing for simpler application of current or future brushless motor technology, electronic control, battery storage and other auxiliary components. It is thus said to be a simpler and more effective way of implementation of electronic motor power as motor fixtures, drives, gears and auxiliaries can be designed into the frame and assembled together before completing the frame. This is somewhat different to a conventional tubular bicycle frame of a metallic or other construction; in which for example a metallic tube in a raw form is generally of a small diameter, is initially tubular in a raw form and inherently difficult to breach open and insert drives, motor fixtures or any other types of electronic devices that might be needed for an electronically controlled bicycle. Having a modular frame design allows for consideration for these components in an embodiment of the current design and thus potential remains for the implementation of components for an electronic powered bicycle.

Claims

CLAIMSWhat claimed is; 1. A vehicle in the form of a composite bamboo hollow bicycle frame, comprising a plurality of composite sub-assemblies that are formed of sheet veneer bamboo or other ligneous materials that sandwich a woven fiber fabric between them such as Glass, Carbon, or Flax using an epoxy resin system as the adhesive. Said frame assembles in such a way that the sub assemblies form the outer four walls of the hollow non-tubular frame and are located on the main fixing sub-assemblies located in the head tube, bottom bracket and seat post. Due to the perpendicular joins of the said frame sub-assembly sidewalls the said frame is mostly hollow and non-tubular, distinctly differentiating itself from a standard tubular bicycle frame. The design in the current invention allows for a simple assembly technique wherein parts are brought together in a parallel plane to fit onto the sub-assembly fixtures and further internal and external subassemblies complete the hollow frame sections. It is claimed that tooling is thus reduced in the current invention and manufacturing flexibility increased due to the nature of how the sub-assemblies are pre cured before assembly. The current invention is a modular bicycle frame construction, using the said materials and allowing for the said advantages.
2. The frame set forth in Claim 1 is comprised of the following; a frame; a head tube fixture, a bottom bracket fixture, a seat post sub fixture, a left and right side of frame sub-assembly of a sandwich construction making up the left and right wall of the side frame comprising part of the down tube, seat tube and top tube; a plurality of internal and external sub-assemblies for completing the hollow frame construction, a rear left and right chain stay comprised of laminated bamboo and woven fabric material molded into desired shape, a rear left and right seat stay comprised of laminated bamboo and woven fabric material molded into desired shape, a rear hanger for attachment of wheel comprised of a metallic material, a plurality of metallic components to interface with the insertion of standardized bottom bracket sealed axle and bearings, insertion headsets and bearings, forks and insertion of seat posts.
3. The frame as set forth in Claim 1 and non metallic structures as said in Claim 2 are comprised of a stock post processed bamboo veneer or equally any other ligneous stock sheet product from which the individual part profiles are cut, quantity and thus nesting is determined by the thickness of said sub assembly parts.
4. The frame as set forth in Claim 1 and its non metallic structures as said in Claim 2 make use of bamboo as a sustainable raw material, thus lending the current invention towards a sustainable eco-friendly design.
5. The thickness of said sub-assemblies in Claim 2 are created by laminating said veneers between woven fiber fabric using an epoxy resin system and tooling, that allows for either wet layup or pre pregnated systems to be used, to create the desired part thickness geometry.
6. The frame set forth to any proceeding claim makes use of an epoxy resin system as the adhesive for the said laminates and assembly of the subassemblies into the bicycle frame as said in Claim 1. Said epoxy resin systems are chosen to optimise performance properties of chosen composite materials as said in Claim S and improve efficiency of manufacture with respect to cure cycles. The current invention allows for use of eco friendly epoxy resin systems to further differentiate the current invention as a sustainable eco-friendly design.
7. The frame set forth to any proceeding claim, said sub-assemblies make use of high strength to weight materials, with high specific strength properties to provide said sub-assemblies with user specific performance properties.
8. The cut parts as said set forth in Claim 3 that make up the sub-assembly parts as set forth in Claim 2 & 5 make use of the raw bamboo or ligneous material and its inherent fiber orientation to increase performance and/or visual aesthetics of each individual sub-assembly. Multiple fiber orientations are achieved through different nesting of part outlines on the said stock material. Said bamboo and/or ligneous profiled parts in the sub-assembly can be of different thicknesses dependent upon design requirements.
9. The frame as set forth and its part generation as set forth in Claim 3 distinguishes the design for a mass production environment by reducing stock material, machining time and lends itself to simpler and faster machining in the form of 2D or 2 /2 D vertical milling, laser cutting or water cutting.to. The tooling to create the said left and right side of frame sub-assembly parts as set forth in Claim 2 is achieved through compressional molding in the form of vacuum, pneumatic press or other compressional molding techniques. The geometrically flat nature of said sub assemblies lends itself to reduced tooling costs and possibility of multiple bicycle sub-assemblies manufactured in one tool.11. The tooling to create the said chain stay and seat stay as in Claim 2 is achieved by forming the said veneered laminate in Claim 5 over a contoured tool to generate a bent laminate.12. The process of compressional molding to generate said frame in Claim 1 and thus sub-assemblies as set forth in Claim 2 can use metallic or composite tools with the addition of heat and significant pressure to achieve the desired said sub-assembly strength.13. The frame as set forth in Claim 1 uses fixtures in the head tube, bottom bracket and seat post as said in Claim 2. These said fixtures make use of post processed stock bamboo in thicker laminates up until their maximum stock thickness, further thicknesses can be achieved by manually laminating said bamboo veneer to desired thickness.14. The bottom bracket, seat post and head tube fixtures as said forth in Claim 2 are machined using a vertical milling machine.15. The fixtures as set forth in Claim 2 are the primary module in the assembly of the said frame. In the current invention the fixtures allow for the addition of the left and right side frame sub-assemblies as said in Claim 2 fitting in a parallel, and are in themselves tooling to locate these said assemblies. The inner and outer sub-assemblies as set forth in Claim 2 then fit to complete the hollow non-tubular frame and close any gaps in the said frame.16.A processes synonymous with modular construction is apparent in the assembly of the current invention, with said sub assemblies as set forth in Claim 2 being built individually prior to a jig saw assembly technique that is in the form of bottom-up. The technique of interlocking said subassemblies of the side of the frame and inner/outer sub assembly parts creates a perpendicular interface for adhesion and structural integrity to create a hollow frame section.17. The frame as set forth in Claim 1 utilises a finishing technique wherein the outer surface of the sub assemblies is covered in a Polybutylene terephthalate (PBTJ top sheet or other plastic based top sheet material that improves the environmental protection of the finished bicycle. Said top sheet material forms a protective layer once said sub assembly frame parts are press molded, said top sheet also allows for better mold release and application of graphics. Said top sheet allows for application of graphics in the form of sublimation, water transfer sticker, digital printing or any other appropriate graphic printing medium. Other finishing such as Acrylic, UV, Gel Coat Epoxy, or similar environmental barrier sprays can be used on the current invention alongside a top sheet material.18. The frame as set forth in Claim 1 once assembled will allow for the addition of metallic parts inserted into the head tube) bottom bracket and seat post to accommodate the fitment of common bicycle components such as wheels, seat posts, forks, handle bars, bottom brackets, brakes and crank sets.19. The frame set forth in Claim 1 in order to attach the conventional bicycle wheel, hub and axle requires the addition of a metallic or composite structure that is b&ted or fused within the rear stays during curing to serve the purpose of providing a location for the axle of the wheel to spin freely.20. The frame set forth to Claim 1 allows for the addition of an impact resistant PU, ABS or similar plastic material to the said bamboo veneer sheet in Claim 3, which would be inserted or if PU injected around the profile of the parts to create a perimeter around each individual said sub assemb'y parts. The construction in Claim 16 allows for this said material to exist on the outer surface of each part interacting at the perpendicular joint location and once the said frame is finished will be a protective layer against impacts and the environment.21. The chain stay and seat stay as set forth in Claim 2 in the current invention is assembled onto the main frame by use of an adhesive, locating joint and in some versions may be bolted in place using a metallic fastener. The type of joint and/or fastener used can depend upon design aesthetics and performance criteria.