Power Switching Structure for Accurate Bicycle Torque Sensing
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Solution Overview
Problem
Existing bicycle torque detection mechanisms suffer from measurement errors due to torque transmission to the chain wheel, leading to inaccurate assisting power output and potential part damage during direct driving.
Innovation Solution
The use of a detection shaft sleeve to indirectly drive transmission sleeves with micro-motion static frictional forces, combined with one-way bearings, allows for accurate torque measurement and flexible power selection to prevent measurement errors and ensure smooth assisting power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a strain gauge is attached to the crankshaft surface for torque detection, then the torque can be detected, but measurement errors occur due to torque transmission to the chain wheel
Solution Approach 1:
The system is divided into separate functional components: the input shaft for power input, the detection shaft sleeve for torque detection, and the output assembly for power transmission. This segmentation isolates the detection function from the power transmission path, preventing torque transmission errors from affecting measurement accuracy.
Solution Approach 2:
The detection shaft sleeve acts as an intermediary between the input shaft and the output assembly. It indirectly drives the transmission sleeves through micro-motion static friction, allowing accurate torque measurement without direct connection to the chain wheel, thus eliminating measurement errors caused by power transmission.
2Productivity
If the crankshaft directly drives the chain wheel, then power transmission is direct, but torque measurement accuracy deteriorates
Solution Approach 1:
The power transmission system is segmented into independent modules: input shaft, detection shaft sleeve, transmission sleeves, and output member. This allows the detection function to be separated from the power transmission path, maintaining both measurement accuracy and transmission efficiency.
Solution Approach 2:
The detection shaft sleeve serves as a mediator that indirectly drives the transmission sleeves through controlled micro-motion friction. This intermediary mechanism enables accurate torque measurement while maintaining efficient power transmission to the output member.
3Power
If primary power and assisting power are applied simultaneously, then driving capability is enhanced, but interference between power sources causes part damage
Solution Approach 1:
The system dynamically switches between different power sources (primary power from input shaft, assisting power from motor, or external power) based on operational needs. The one-way bearings enable flexible power selection, allowing the system to adapt to different driving conditions while preventing power source interference and potential damage.
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 solution reduces measurement errors, provides stable and smooth assisting power output, and enhances operational flexibility by preventing interference between primary and assisting power sources.
Implementation Method 1
a phenomenon of micro-motion static frictional force is induced between the first and second transmission sleeves and the input shaft, allowing the detection shaft sleeve to directly and accurately measure a torque value of the input shaft
Implementation Method 2
based on the arrangement of the one-way bearings between the second transmission sleeve and the first transmission sleeve and the power member, the output member of the second transmission sleeve may select a source of power
Data Source
AI summary
A power switching structure includes an input shaft, a detection shaft sleeve fit over the input shaft, an assisting power assembly, and an output assembly selectively drivable by the input shaft and the assisting power assembly. The output assembly includes first and transmission sleeves rotatably mounted to the input shaft. The assisting power assembly includes a power member rotatably mounted to the second transmission sleeve. A one-way bearing is arranged between the first and second transmission sleeves and the power member. An output member is mounted on the second transmission sleeve. A micro-motion static frictional force is induced between the first and second transmission sleeves and the input shaft to allow the detection shaft sleeve to directly and accurately measure a torque value of the input shaft. The one-way bearing arranged between the first and second transmission sleeves and the power member allows for selection among sources of power.