E-Bike Torque Coupling for Mechanical Freewheel Switching
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Solution Overview
Problem
Existing torque transmission arrangements in human-powered vehicles with auxiliary motors are prone to errors and require redundant electrical systems for safety, and they often necessitate separate freewheels for efficient freewheeling functions, leading to complex and costly designs.
Innovation Solution
A mechanical clutch system that transfers torque from the second input shaft to the output shaft only when the first input shaft rotates in the driving direction, and prevents torque transmission when rotating in the opposite direction, integrated with a clamping lock mechanism for reliable operation without electrical power, allowing for a compact and cost-effective design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If electrical sensors and systems are used to detect pedal pressure and control auxiliary motor support, then the system can automatically switch on/off motor assistance, but the system becomes prone to errors, faults, and requires redundant electrical systems for safety
Solution Approach 1:
The patent replaces electrical sensors and control systems with a purely mechanical clutch mechanism that automatically engages and disengages based on the direction of pedal rotation. The clutch uses a cam mechanism with a roller follower that passively responds to rotational direction changes, eliminating the need for electrical detection and control systems while improving reliability.
Solution Approach 2:
The mechanical clutch system is self-regulating and requires no external control input. The cam mechanism automatically engages the clutch when the pedal rotates in the driving direction and disengages when rotated in the opposite direction, making the system self-service and eliminating the need for redundant safety systems.
2Reliability
If separate freewheels are installed in the auxiliary motor and gearbox to prevent motor turning during backward pedaling, then both freewheeling functions are ensured, but the device complexity and cost increase
Solution Approach 1:
The patent combines both freewheeling functions into a single mechanical clutch mechanism. The cam-based clutch simultaneously prevents the auxiliary motor from turning during backward pedaling and enables automatic disengagement when the pedal rotates opposite to the driving direction, eliminating the need for separate freewheels in the motor and gearbox.
Solution Approach 2:
The mechanical clutch serves multiple functions: it acts as a freewheel for the auxiliary motor, a one-way clutch for the gearbox, and an automatic engagement mechanism based on rotation direction. This multi-functionality reduces the overall number of components and simplifies the drive train.
3Productivity
If the output shaft is firmly connected to the first input shaft or formed by it, then torque transmission is direct and efficient, but the mechanical clutch mechanism becomes more complex to integrate
Solution Approach 1:
The patent nests the mechanical clutch mechanism within the existing shaft structure. The cam mechanism is integrated into the output shaft assembly, with the roller follower positioned to interact with the cam profile during rotation. This nesting approach maintains direct torque transmission while incorporating the clutch function without adding external complexity.
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
Ensures reliable switching off of auxiliary motor support and integrates both freewheeling functions in a single unit, reducing the risk of electrical failures and enabling a lightweight, compact design while maintaining high torque transmission capabilities.
Implementation Method 1
a clamping element (4) which is designed to transfer a torque from the second input shaft (2) to the output shaft (3) through frictional contact
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention relates to a torque transmission arrangement for the drive train of a human-powered vehicle with an auxiliary motor. The torque transmission arrangement comprises an output shaft, a first input shaft for transmitting torque generated by muscle power to the output shaft, a second input shaft for transmitting torque generated by the auxiliary motor to the output shaft, and a freewheel function that prevents a user of the human-powered vehicle from having to turn the auxiliary motor when the auxiliary motor is switched off.According to the invention, the torque transmission arrangement has a coupling designed to transmit a torque from the second input shaft to the output shaft when a torque acting on the output shaft in a drive direction is applied to the first input shaft, and not to transmit a torque from the second input shaft to the output shaft when a torque acting on the output shaft in the opposite direction to the drive direction is applied to the first input shaft.