Front Sprocket Slide-Shaft Support for Rigid Chain Drive
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Solution Overview
Problem
The existing front sprocket assembly for human-powered vehicles, such as bicycles, lacks sufficient strength and rigidity, leading to inefficient drive force transmission from the front sprocket to the rear sprocket assembly due to insufficient support of the slide shaft under load from the bicycle chain.
Innovation Solution
The front sprocket assembly incorporates a sprocket-displaceable structure with a slide shaft supported by first and second shaft-supporting portions, allowing the front sprocket to displace relative to the sprocket carrier, and includes a slide member with a base metal and resin layer for secure fixation and smooth sliding, utilizing materials like iron and polytetrafluoroethylene for enhanced durability and reduced backlash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the slide shaft is supported in a cantilevered manner by the sprocket carrier, then the device complexity is reduced, but the strength and rigidity of the slide shaft become insufficient under load
Solution Approach 1:
The support structure for the slide shaft is segmented into multiple discrete support portions (first shaft-supporting portion and second shaft-supporting portion) spaced apart along the shaft axis, transforming the single cantilevered support into a distributed multi-point support system that enhances strength while maintaining structural simplicity
Solution Approach 2:
The support arrangement transitions from a single-point cantilevered support to a multi-point distributed support along the axial dimension of the slide shaft, utilizing the axial spacing between support portions to increase structural rigidity and load-bearing capacity
2Productivity
If the front sprocket is fixed rigidly to the sprocket carrier, then the drive force transmission efficiency is improved, but the ability to accommodate chain tension variations and prevent disengagement is reduced
Solution Approach 1:
The front sprocket is designed with dynamic displacement capability along the axial direction through the slide shaft mechanism, allowing it to move relative to the sprocket carrier to accommodate chain tension variations while maintaining effective torque transmission through the engaged sprocket teeth
Solution Approach 2:
The slide shaft acts as an intermediary element between the front sprocket and the sprocket carrier, enabling controlled axial displacement of the sprocket while maintaining torque transmission, thus mediating between the requirements for rigid power transmission and flexible chain engagement
3Ease of operation
If a slide member with resin layer is added to the slide shaft assembly, then the smooth sliding and reduced backlash are achieved, but the device complexity increases
Solution Approach 1:
The slide member is constructed as a composite structure with a base metal substrate providing structural support and a resin layer (containing PTFE) providing low-friction sliding surface, combining the advantages of metal strength and resin lubricity to achieve smooth operation
Solution Approach 2:
The friction parameter of the sliding surface is changed by applying a resin layer with low-friction properties (PTFE) onto the slide member, transforming the sliding interface from high-friction metal-to-metal contact to low-friction metal-to-resin contact, thereby achieving smooth sliding and reduced backlash
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 configuration improves the strength and rigidity of the sprocket-displaceable structure, ensuring efficient drive force transmission and prolonged smooth operation by securely fixing the slide member to the slide opening and allowing the front sprocket to slide smoothly over the slide shaft, thereby enhancing load resistance and reducing weight while maintaining strength.
Implementation Method 1
The resin layer is made of a resin material including solid lubricant... configured to slide relative to the at least one slide shaft
Data Source
AI summary
A front sprocket assembly basically includes a front sprocket, a sprocket carrier and at least one slide shaft. The front sprocket includes a sprocket body having at least one carrier mounting portion. The at least one carrier mounting portion has the at least one slide opening. The sprocket carrier includes at least one sprocket mounting portion. The at least one sprocket mounting portion has a first shaft-supporting portion and a second shaft-supporting portion. The at least one slide opening receives the at least one slide shaft between the first shaft-supporting portion and the second shaft-supporting portion.