Bicycle Crank Assembly Axial Sprocket Support
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bicycle crank assemblies face challenges in maintaining the strength of the part that supports the sprocket member, especially when the chain is disposed at an angle, leading to potential chain derailment due to reduced support strength.
Innovation Solution
The bicycle crank assembly features a support portion and a sliding portion that extend and slide in the axial direction, with rolling members and a reinforcing member to enhance support strength, reduce sliding resistance, and allow for smooth sprocket movement, while also incorporating a tool-free stopper member for easy sprocket attachment and detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sprocket member is supported by the crank member or radial part to be movable in the axial direction, then the chain derailment is prevented, but the strength of the support part is reduced
Solution Approach 1:
The support structure is divided into multiple independent support portions distributed around the rotational axis. Each support portion provides individual support to the sprocket member, collectively maintaining high strength while allowing axial movement to prevent chain derailment.
Solution Approach 2:
The support portions are arranged in the circumferential direction around the rotational axis, transitioning from a single-point support to a distributed multi-point support system. This spatial arrangement increases the overall support strength while maintaining the ability of the sprocket member to move axially.
2Strength
If the sprocket member is fixed firmly to the crank member, then the support strength is maintained, but the chain may come off when disposed at an angle
Solution Approach 1:
The support structure transitions from a fixed connection to a dynamic connection that allows axial movement. The support portions enable the sprocket member to move axially in response to chain tension forces, maintaining firm support in the radial direction while accommodating axial displacement to prevent chain derailment.
Solution Approach 2:
The degree of freedom of the sprocket member is adjusted by allowing axial movement while maintaining radial fixation. This parameter change enables the system to adapt to varying chain tension conditions, maintaining support strength when needed while preventing derailment when the chain is at an angle.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design maintains high support strength for the sprocket member, reduces the likelihood of chain derailment, and facilitates easy assembly and maintenance by allowing for adjustable movement and smooth operation with reduced backlash and foreign matter protection.
Implementation Method 1
at least one rolling member 22 which is disposed between the support portion 40 and the sliding portion 44
Data Source
AI summary
A bicycle crank assembly having a rotational center axis is basically provided with a crank member and a sprocket member. The crank member includes a support portion that extends in the axial direction and an arm portion that is integrally rotatable around the rotational center axis with the support portion. The sprocket member includes a sliding portion that extends in the axial direction that is integrally rotatable with respect to the support portion and that is displaceable in the axial direction. The bicycle crank assembly is constructed to achieve high strength and to suppress the decrease in the efficiency of the rotation transmission from the crank member to the sprocket member in a crank assembly in which the sprocket member is movable in the axial direction.