E-bike Drive Unit Idle Gear Reduces Rear Center Length
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Solution Overview
Problem
The existing drive units for electrically assisted bicycles, when positioned at the center of the frame, increase the rear center length, leading to decreased agility and limited ground clearance, restricting the vehicle's operational range and performance, especially on non-asphalt roads.
Innovation Solution
The use of an idle gear in the drive unit's transmission mechanism allows for a reduction in the diameter of the driven gear without increasing the unit's width, thereby shortening the rear center length and enhancing the positional arrangement of components, thus decreasing the overall size of the drive unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the drive unit is positioned at the center of the frame to improve weight balance and component integration, then the rear center length increases, but the vehicle agility and ground clearance decrease
Solution Approach 1:
The patent repositions the pedal crank shaft from a horizontal orientation to a vertical orientation, changing the spatial dimension of component arrangement. This dimensional change allows the drive unit to be positioned more compactly, reducing the rear center length while maintaining central mounting benefits for weight balance and component integration.
2Device complexity
If the drive unit is positioned at the center of the frame, then component integration is improved, but the ground clearance is reduced, limiting operational range
Solution Approach 1:
By changing the pedal crank shaft orientation to vertical and repositioning the drive unit components in three-dimensional space, the patent achieves better component integration while minimizing the horizontal footprint, thereby preserving ground clearance for off-road operation.
Solution Approach 2:
The patent integrates multiple components (electric motor, decelerator, pedal crank shaft, controller) into a compact hierarchical arrangement where smaller components are positioned within or adjacent to larger ones, maximizing space utilization and reducing the overall drive unit footprint.
3Device complexity
If the drive unit size is increased to accommodate all components, then component integration is improved, but the positional arrangement of surrounding parts is restricted
Solution Approach 1:
The patent employs a nested arrangement where the decelerator, pedal crank shaft, and other components are positioned within the housing structure in a hierarchical manner, allowing all components to be integrated while maintaining a compact external dimensions that preserve freedom for surrounding component placement.
Solution Approach 2:
The vertical orientation of the pedal crank shaft and three-dimensional positioning of components within the housing allows integration of multiple components without increasing the horizontal footprint, thereby preserving positional arrangement freedom for battery, suspension, and other surrounding parts.
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
This configuration reduces the size of the drive unit, improves the degree of freedom in component arrangement, and maintains or increases ground clearance, enhancing the vehicle's agility and operational range without increasing the front center length, allowing for easier integration of a larger battery capacity.
Implementation Method 1
The transmission includes a decelerator rotatably supported by the housing in the housing, and an idle gear rotatably supported by the housing in the housing. The decelerator increases the torque of the output shaft of the electric motor, and the increased torque is transmitted to the driven gear via the idle gear.
Data Source
AI summary
A drive unit includes an electric motor including an output shaft including an output gear; a pedal crank shaft extending through a housing, rotatably supported by the housing, and including a driven gear; and a transmission to transmit a torque of the output gear of the electric motor to the driven gear. The transmission includes a decelerator rotatably supported by the housing, and an idle gear rotatably supported by the housing. The decelerator increases the torque of the output shaft of the electric motor, and the increased torque is transmitted to the driven gear via the idle gear.