Pedally Propelled Vehicle Drive Train with Torque Limiting
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Solution Overview
Problem
Existing pedally propelled vehicles with crank drives face issues of long-term reliability, high maintenance costs, and heavy weight, particularly those with integrated electric motors and multi-speed gears, limiting their applicability.
Innovation Solution
A compact, integrated pedally propelled drive train system comprising a crankshaft, motor, and internal multi-speed gear with a torque limiter and one-way clutches to manage peak torques, reducing component size, weight, and maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an integrated electric motor and multi-speed gear are added to the crank drive, then the vehicle assistance performance is improved, but the weight increases significantly
Solution Approach 1:
The patent places the electric motor and multi-speed gear system inside the crank arm structure, nesting multiple functional components within the existing crank arm volume. This integration allows the motor and gear mechanism to share structural space with the crank arm, reducing overall weight while maintaining full functionality of both power assistance and gear shifting capabilities
2Power
If a multi-speed gear system with integrated motor is implemented, then the performance is improved, but the device complexity increases making it applicable only for limited applications
Solution Approach 1:
The crank arm is designed to serve multiple functions simultaneously: it acts as the pedal drive structure, houses the electric motor, contains the multi-speed gear mechanism, and provides mounting points for all components. This multi-functional integration reduces the number of separate parts and simplifies the overall drive train architecture while maintaining advanced performance capabilities
3Weight of moving object
If the peak torque from the crank shaft is reduced to make components smaller, then the weight and cost are reduced, but the torque transmission capability may be compromised
Solution Approach 1:
The patent employs a variable ratio multi-speed gear system that can change transmission ratios between different pedaling conditions. During high-torque situations, the system engages lower gears with higher mechanical advantage to maintain torque transmission capability, while during normal cruising conditions, higher gears reduce the effective torque demand on components, allowing for smaller, lighter component design without sacrificing peak performance
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 system achieves reduced weight and lower maintenance costs while maintaining performance, enhancing the driving experience and energy efficiency.
Implementation Method 1
The torque limiter comprises a crankshaft wheel one-way rotationally connected to the crankshaft via a one way clutch
Implementation Method 2
The torque limiter is configured to protect drive train components downstream from the crankshaft by limiting peak torques from the crank shaft
Data Source
AI summary
A pedally propelled vehicle drive train includes a housing, a crankshaft, an internal multi-speed gear with co-axial input and output shafts, and an electric motor with an output shaft. The crankshaft, the input and output shafts of the internal multi-speed gear and the output shaft of the electric motor are all arranged in parallel.