E-Bike Pushing Aid Gearshift Control for Consistent Low-Speed Torque
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Solution Overview
Problem
Existing electric bicycles with a pushing aid function face issues with inconsistent propulsion due to dependence on the current transmission of the drive train, leading to inefficient support that can be too weak or too strong, and speed detection at low speeds is often inaccurate.
Innovation Solution
An optimized pushing aid method for electric bicycles that adjusts the gearshift transmission ratio based on current conditions, using electronic actuation to ensure a constant motor torque and optimal support by controlling the gearshift according to factors like transmission ratio, speed, and incline, thereby maintaining a predetermined maximum speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pushing aid motor torque is transmitted via the existing drive train with fixed gearshift, then the drive train structure is simple, but the propulsion becomes inconsistent and too weak or too strong depending on current transmission ratio
Solution Approach 1:
The gearshift transmission ratio is made dynamically adjustable during pushing aid operation. The control unit automatically selects and switches between different transmission ratios based on detected pushing conditions (speed, incline, torque), transforming the static transmission system into a dynamic one that adapts to varying operational requirements, ensuring consistent propulsion force.
Solution Approach 2:
The transmission ratio parameter is changed automatically by the control unit based on detected pushing conditions. By monitoring parameters such as wheel speed, incline angle, and motor torque, the system adjusts the transmission ratio to optimize the pushing aid effect, ensuring that the propulsion remains consistent across different operating conditions without manual intervention.
2Object-affected harmful factors
If the maximum speed of the electric bicycle generated by the pushing aid is limited to 6 km/h, then safety is improved, but speed detection accuracy deteriorates at such low speeds
Solution Approach 1:
The control unit acts as an intermediary that calculates pushing aid motor speed based on motor torque and transmission ratio rather than relying solely on wheel speed sensors. This alternative measurement approach provides accurate speed information even at very low speeds where traditional wheel speed detection becomes unreliable, while still maintaining the 6 km/h safety limit.
Solution Approach 2:
The mechanical speed detection system (wheel speed sensors) is supplemented or replaced by a calculation-based speed determination method. By using the relationship between motor torque, transmission ratio, and motor speed, the system achieves accurate speed measurement at low velocities without relying on mechanical sensors that struggle at such low speeds.
3Reliability
If the transmission ratio is adjusted to provide optimal pushing aid torque, then propulsion consistency is improved, but the device complexity increases due to electronic gearshift control
Solution Approach 1:
The electronic gearshift control system serves multiple functions: it optimizes pushing aid torque by adjusting transmission ratio, maintains maximum speed limits, and adapts to various pushing conditions (incline, speed, torque requirements). By consolidating these functions into a single multi-functional control unit, the patent reduces overall system complexity despite the added capability.
Solution Approach 2:
The control unit automatically monitors pushing conditions and adjusts the transmission ratio without requiring manual intervention from the rider. The system self-regulates by detecting parameters such as wheel speed, incline, and torque, then autonomously selecting the appropriate gear ratio to maintain optimal pushing aid performance, eliminating the need for complex manual control mechanisms.
Data Source
AI summary
A method for operating a pushing aid of an electric bicycle is disclosed. The electric bicycle includes a drive unit for generating a propulsion and a gearshift between the drive unit and a drive wheel of the electric bicycle. The gearshift is designed to be electronically operable. The method includes the following steps of which are carried out in a pushing aid mode of the electric bicycle (i) determining a current transmission ratio of the gearshift, (ii) operating the drive unit to generate a pushing aid motor torque, and (iii) controlled adjustment of the transmission ratio of the gearshift as a function of the determined current transmission ratio.