Patent Application
20180086136
The disclosure relates to a reinforcing structure of a carbon fiber rim. More particularly, the disclosure relates to a reinforcing structure of a carbon fiber rim for decreasing the overall weight.
Rims of bicycles may be made from aluminum alloy or carbon fiber. These two materials both have advantages and disadvantages. The aluminum alloy has advantages of high ductility and low cost, but has disadvantages of low hardness and heavy weight. Contrarily, the carbon fiber has advantages of high hardness and lightweight, but has disadvantages of low ductility and high cost. However, components of high-grades bicycles using carbon fiber composite materials has become a common practice. The carbon fiber materials having properties of high strength, high rigidity, and light weight applied on components of bicycles can satisfy the requirements of bicycle's industry.
In the manufacturing process of carbon fiber rims, both cost and lightweight need to be considered. Therefore, the carbon fiber rims in the market all have hollow annular structures, which are made by stacking carbon fiber cloth and then thermal compression. Therefore, the structural strength of some parts, such as at the spoke assembling positions, can be decreased by hole formation. Since the ductility of the carbon fiber is decreased after curing, in addition to the hollow structure, the stress and the tension applied on the spoke assembling positions, the rim can be damaged due to the insufficient strength. Especially, when the carbon fiber rim is pulled by external forces, the spoke assembling positions of the rim will be broken and damaged since cannot withstand the external forces to affect the overall strength of the carbon fiber rim. Thus, the carbon fiber rim cannot operate normally.
In light of the drawbacks above, Taiwan Patent No. 1374814 B discloses a multi-layer reinforcement element applied on at least one portion of the inner annular side of a bicycle rim. The multi-layer reinforcement element comprises an inner annular side, an outer annular side, and an intermediate portion between the inner annular side and the outer annular side. The intermediate portion is in a frustum of pyramid-like configuration comprising at least two layers and four inclined areas. Taiwan Patent No. 1341799 B discloses a bicycle rim, which comprises an annular metallic rim member and a reinforcing member. The annular metallic rim member includes a pair of opposite-facing annular brake surface and a plurality of spoke attachment areas with at least one spoke attachment opening in each of the spoke attachment areas. The reinforcing member overlies an exterior surface of the annular metallic rim member, but not the annular brake surface. The reinforcing member includes a plurality of spoke attachment sections individually arranged in a circumferential direction to overlie the spoke attachment openings. The spoke attachment sections include a plurality of discrete first reinforcing parts and a plurality of discrete second reinforcing parts. The first reinforcing parts are attached to the spoke attachment areas around the spoke attachment openings. The second reinforcing parts are attached to the spoke attachment areas to overlie the first reinforcing parts, with the second reinforcing parts being larger than the first reinforcing parts.
However, the structures above have the drawbacks illustrated below.
1. Those are local strengthen technology to the spoke attachment portions, and the overall weight is thus increased. At the same time, when the spokes attaching portions are pulled by external forces applied on the corresponding spokes, stress problems will occur to cause broken phenomenon at the spokes attaching portions.
2. As stated above, in the process of covering carbon fiber layers, the defect rate is easily occurred.
3. Relatively, the cost is increased.
In one aspect, a reinforcing structure of a carbon fiber rim is provided. Especially, this reinforcing structure can increase the tensile strength of the carbon fiber rim and decrease the overall weight of the carbon fiber rim.
The reinforcing structure of a carbon fiber rim comprises a rim body and metal reinforcing sheets. The rim body is made from a carbon fiber material. The rim body comprises an external diameter edge to be assembled with a tire, an inner diameter edge to be assembled with hubs and spokes, and two side sections between the outer diameter edge and the inner diameter edge. Metal reinforcing sheets are disposed on spoke assembling positions of the inner diameter edge and wrapped by the carbon fiber material, and each has two opening edges and a middle ring section connecting the two opening edges. A thickness is decreased from the middle ring section to the two opening edges. The middle ring section is disposed with a reinforcing part corresponding to the inner diameter edge of the rim body and two reinforcing edge parts corresponding to two side edge sections. A thickness is increased from the reinforcing edge parts to the reinforcing part. Therefore, the tensile strength at the spoke assembling positions can be effectively increased and achieve the lightweight effect.
In an embodiment of this invention, a through hole is disposed on the reinforcing part on each metal reinforcing sheet for assembling with a spoke.
In an embodiment of this invention, the metal reinforcing sheets are made from aluminum alloy, magnesium alloy, or aluminum-magnesium alloy.
In an embodiment of this invention, a ratio of a minimum thickness of the reinforcing edge parts to a maximum thickness of the reinforcing parts is 1:3 to 1:6.
First, please refer to
The rim body 1 is made from carbon fiber. The rim body 1 comprises an external diameter edge 11 to be assembled with a tire, an inner diameter edge 12 to be assembled with hubs and spokes, and side edge sections 13 between the outer diameter edge 11 and the inner diameter edge 12.
The metal reinforcing sheets 2 are wrapped by the carbon fiber of the rim body 1 and located at spoke assembling positions on the inner diameter edge 12 of the rim body 1. Corresponding to the radial direction of the rim body 1, the metal reinforcing sheets 2 have two opening edges 21 and a middle ring section 22 connecting the two opening edges 21. A thickness is decreased from the middle ring section 22 to the opening edges 21. The middle ring section 22 of each metal reinforcing sheet 2 is disposed with a reinforcing part 221 corresponding to the inner diameter edge 12 of the rim body 1 and two reinforcing edge parts 223 corresponding to the two side edge sections 13 of the rim body 1. The reinforcing part 221 has a through hole 222 to be assembled with a spoke. The reinforcing edge parts 223 are formed at two sides of the reinforcing part 221. A thickness is increased from the reinforcing edge parts 223 to the reinforcing part 221.
As shown in
When the metal reinforcing sheets 2 are placed in molds, the carbon fiber cloth is attached from inside to outside. The carbon fiber cloth is attached on the middle ring section 22 toward the opening edges 21 and condensed gradually, so that the inside and outside carbon fiber cloth can be tightly sealed and integrated as one. At the time of attaching the carbon fiber cloth to form the side edge sections 13, through the design of gradually increasing the thickness from the reinforcing edge parts 223 to the reinforcing part 221, the carbon fiber can be smoothly attached to combine the reinforcing edge part 223 and the side edge sections 13 of the rim body 1 together.
In order to reinforce the tensile strength of the rim body 1, a preferred ratio was obtained via many times of experiments. The ratio of the minimum thickness to the maximum thickness of the thickness from the reinforcing edge parts 223 to the reinforcing part 221 was in a range from 1:3 to 1:6.
Comparing with the conventional structures, the reinforcing structure has the following advantages:
1. In this invention, since the metal reinforcing sheets are disposed on the spoke assembling positions of the rim, the tensile strength of the rim can be effectively increased to enhance the tensile property.
2. In this invention, the metal reinforcing sheets are disposed on the spoke assembling positions of the rim. This distribution on the key positions can increase the tensile strength and further achieve the purpose of lightweight.
3. In this invention, the thickness gradually decreasing design on the opening edges can make the carbon fiber cloth attached on the rim body more tightly. Therefore, no interspaces can destroy the strength to achieve the perfect combine technology.
4. In this invention, the thickness gradually increasing design from the reinforcing edge parts to the reinforcing part can connect the side edge sections of the rim during the period of attaching the carbon fiber cloth to effectively increase the stress effect of the side edge sections.
