Bicycle Bottom Bracket Force Sensor Installation
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Solution Overview
Problem
Existing bicycle force sensor arrangements are complex and prone to damage during installation, requiring complete disassembly of the crank assembly and exposing sensors to risk of damage.
Innovation Solution
A force sensor assembly for a bicycle that includes an outer portion, an inner portion, at least one sensor mounting surface, and a strain gauge, with the strain gauge protected by a cover, allowing easy installation and removal from the bottom bracket tube, and featuring an adaptor member with sensor mounting portions that support the main body and protect the strain gauges during installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If sensors are positioned between the bottom bracket tube and crank axle bearing with exposed outer surfaces, then the sensors can detect force during installation, but the sensors are exposed to damage during the installation process
Solution Approach 1:
The force sensor assembly is divided into separate components: an adaptor member with bearing receiving portion, a main body with strain gauges, and a cover. This segmentation allows the strain gauges to be protected within the main body during installation while still enabling force detection when assembled.
Solution Approach 2:
The strain gauges are pre-installed and protected within the main body housing before the assembly is installed onto the bottom bracket tube. The cover is positioned to protect the strain gauges during the installation process, preventing damage before the sensor is operational.
2Measurement precision
If a cylindrical torsion-detecting sleeve member is installed within the bottom bracket tube, then torque detection is achieved, but complete disassembly of the front crank assembly is required for installation
Solution Approach 1:
The force sensor assembly is designed as a separable unit with an adaptor member, main body, and cover that can be installed as a complete assembly onto the bottom bracket tube without requiring disassembly of the front crank assembly. The adaptor member threads onto the bottom bracket tube independently of the crank assembly.
Solution Approach 2:
The force sensor functionality is extracted from the traditional sleeve member design and implemented as a separate assembly that interfaces with the bottom bracket tube through the adaptor member, eliminating the need to disassemble the front crank assembly for installation.
3Reliability
If the force sensor assembly includes a cover protecting the strain gauges, then the sensors are protected from damage during installation, but the assembly structure becomes more complex
Solution Approach 1:
The cover is integrated with the main body to form a unified protective housing that encloses the strain gauges. This merging of the cover and main body creates a compact assembly that provides protection without adding significant structural complexity.
Solution Approach 2:
The main body serves multiple functions: it houses the strain gauges, provides structural support, and works with the cover to protect the sensitive components. The adaptor member also serves dual purposes by threading onto the bottom bracket tube and providing a mounting surface for the main body.
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
The solution enables easy installation and protection of force sensors, reducing the risk of damage and simplifying the process, while allowing accurate measurement of torque and power applied to the crank axle, enhancing the reliability and usability of the force sensor system.
Implementation Method 1
a strain gauge fixed to the sensor mounting surface
Data Source
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AI summary
A bicycle bottom bracket force sensor includes an outer portion (120), an inner portion (122), at least one sensor mounting surface (152) and a strain gauge (86). The inner portion is dimensioned to receive and support a crank axle bearing that rotatably supports a crank axle. The at least one sensor mounting surface extends between the outer portion and the inner portion has the strain gauge fixed thereto. The sensor mounting surface extends in a direction substantially perpendicular to a rotation axis of the crank axle when the force sensor is coupled to the bicycle bottom bracket.