E-Bike Gear Ratio Estimation for Real-Time Shift Detection
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Solution Overview
Problem
Existing electric assist bicycles require users to visually confirm the gear display and switching unit position to determine the selected gear step, which lacks visibility and user convenience.
Innovation Solution
A gear step estimation method and device that acquires a gear ratio of a switching transmission device, compares it with reference values, and estimates the selected gear step by matching the gear ratio with predefined reference values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If visual confirmation of gear display and switching unit position is required, then the user can determine the selected gear step, but the visibility and user convenience are insufficient
Solution Approach 1:
The patent replaces the mechanical visual confirmation system with an electronic estimation system. The control device calculates gear ratio based on rotational speeds of driving and driven wheels, then estimates the gear step by comparing the calculated ratio with reference values. This substitution eliminates the need for visual confirmation of physical displays and switching unit positions, providing digital information delivery that improves both visibility and user convenience.
2Loss of information
If visual confirmation is required to determine gear step, then the gear selection can be confirmed, but the visibility of gear information is poor
Solution Approach 1:
The patent replaces physical visual displays with electronic calculation and estimation. The control device computes gear ratio from rotational speed data and estimates gear step through comparison with reference values. This electronic approach ensures information is always visible and readable regardless of lighting conditions, eliminating the visibility limitations of physical displays.
3Loss of information
If the user must visually confirm the display and switching unit position, then the gear step can be identified, but it requires additional user action and time
Solution Approach 1:
The patent implements automatic feedback by continuously calculating gear ratio from rotational speed sensors and estimating the current gear step. The control device compares the calculated ratio with reference values and determines the gear step automatically without requiring user action. This feedback mechanism provides real-time gear step information, eliminating the time users would spend visually confirming displays and switching unit positions.
Solution Approach 2:
The system performs self-service by automatically monitoring rotational speeds, calculating gear ratios, and estimating gear steps without user intervention. The control device continuously updates the gear step estimation based on real-time data, freeing the user from the need to manually check or confirm gear selection through visual inspection.
Data Source
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AI summary
A gear step estimation method is of estimating a gear step of a switching transmission device (30) of an electric assist bicycle (10) including a motor (M) and the switching transmission device (30) which is provided in a power transmission path between the motor (M) and a rear wheel (78) and is capable of switching the gear step among n gear steps. The gear step estimation method includes a step of acquiring, at a first time, a detected gear ratio Rd that is a gear ratio of a transmission section that is the entire or partial power transmission path including the switching transmission device (30), a step of comparing the acquired detected gear ratio Rd with n preset gear ratios Ri set within a range of possible gear ratios taken by the n gear steps, and a step of estimating the gear step of the switching transmission device (30) as an m-step in a case where the detected gear ratio Rd matches an m-th preset gear ratios Ri.