Dual Ratio Constant Mesh Gearbox for Electric Vehicle Torque Optimization
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Solution Overview
Problem
Electric vehicles equipped with single speed gearboxes experience sluggish initial acceleration due to suboptimal gear ratios and torque limitations at low speeds, resulting in reduced performance.
Innovation Solution
A dual speed gearbox with a constant mesh design, incorporating a sprag clutch assembly and a multi-plate clutch assembly, allows for direct drive and under drive modes, enabling optimized torque distribution and automatic shifting based on motor speed and gear ratio, with a band brake for reverse mode operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If motor torque is limited at very low rotating speeds due to torque ripple and vibrations, then the motor operates smoothly, but the initial acceleration from standstill is reduced
Solution Approach 1:
The dual-speed gearbox acts as an intermediary between the motor and the wheels. By providing a second gear ratio specifically optimized for low-speed operation, the gearbox compensates for the motor's torque limitations at very low speeds. The gear ratio multiplication provides the necessary torque boost during initial acceleration from standstill, overcoming the motor's inherent torque ripple and vibration issues in this operating range.
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 dual speed gearbox enhances acceleration performance by optimizing gear ratios and torque distribution, providing smoother shifting and improved motor efficiency across the vehicle's operating range.
Implementation Method 1
a sprag clutch assembly contained within the housing, where the sprag clutch permits rotation of the ring gear in a first direction while preventing rotation of the ring gear in a second direction
Implementation Method 2
a band brake translatable from at least a first position to a second position, where the band brake in the first position permits rotation of the ring gear within the housing, and where the band brake in the second position prevents rotation of the ring gear within the housing
Implementation Method 3
a set of planetary gears interposed between the sun and ring gears, where the set of planetary gears are in constant mesh with both the sun and ring gears
Data Source
AI summary
A dual ratio constant mesh gearbox is provided that is suitable for use with an automobile, and particularly well-suited for an electric vehicle. The gearbox, which may be configured either as a manual or automatic gearbox, utilizes a planetary gear set and a pair of clutches to shift between under drive and direct drive modes.