Bicycle Drive Unit Pedaling Force Detection via Axle Strain
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Solution Overview
Problem
Existing bicycle drive units for electrically assisted bicycles have complex configurations for detecting pedaling force, which complicates the detection process.
Innovation Solution
A bicycle drive unit with a simpler configuration that detects pedaling force by transmitting rotation from the crank axle to intermediate and supporting axles, allowing force detection without a gear holder, using a sensor to measure the force acting on the supporting axle, and employing a strain gauge element for precise detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gear holder or similar members are arranged to detect pedaling force directly on the crank axle, then the detection can be performed, but the device complexity increases
Solution Approach 1:
The patent extracts the detection function from the crank axle area and relocates it to the second axle area. By detecting the force on the second axle instead of directly on the crank axle, the complex gear holder structure is eliminated while maintaining detection capability through the force transmission path.
Solution Approach 2:
The second axle acts as an intermediary element that transmits the pedaling force from the crank axle to the detection location. This intermediary approach allows force detection without requiring direct mounting on the crank axle, simplifying the overall device configuration.
2Measurement precision
If the pedaling force detecting device is installed to detect rotating movement around the crank axle, then pedaling force can be detected, but the configuration becomes complicated
Solution Approach 1:
The detection function is extracted from the crank axle rotation detection and relocated to the second axle force detection. This extraction eliminates the need for complex gear holder structures and direct crank axle mounting, making the system easier to operate and configure.
Solution Approach 2:
The patent replaces the mechanical gear holder structure with a direct force detection approach on the second axle. Instead of using mechanical gear engagement to transmit and detect force, the system directly measures the force on the second axle, simplifying the mechanical configuration.
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
Enables precise detection of pedaling force with a reduced and simplified configuration, improving the accuracy and ease of operation in electrically assisted bicycles.
Implementation Method 1
employing a strain gauge element for precise detection
Data Source
AI summary
A drive unit has three axles, three rotation transmitting members and an acting force detecting unit. The first axle is configured to be rotated by a crank arm. The first rotation transmitting member is arranged on the first axle to transmit rotation of the first axle by the crank arm. The second axle is spaced from the first axle. The second rotation transmitting member is arranged on the second axle, and is operatively engaged with the first rotation transmitting member to transmit rotation of the first rotation transmitting member. The third axle is spaced from the first axle and the second axle. The third rotation transmitting member is arranged on the third axle, and operatively engaged with the second rotation transmitting member to transmit rotation of the second rotation transmitting member. The acting force detecting unit arranged to detect a force acting on the second axle.