Pericyclic Speed Reduction Assembly for Electric Vehicles
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Solution Overview
Problem
Electric vehicles require a compact and efficient speed reduction mechanism to lower the high rotational speed of electric machines from 10,000 to 30,000 rpm to a suitable speed for wheel rotation, as existing solutions like planetary gear sets are bulky and inefficient due to increased power losses with more stages.
Innovation Solution
A pericyclic apparatus is used in conjunction with an electric machine and output member to achieve a high speed reduction ratio of 13:1 or greater, utilizing a pericyclic motion converter and reaction control member to connect the output shaft and output member coaxially, reducing the output speed while maintaining mechanical efficiency and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If planetary gear sets or multi-gear/stage intermediate shafts are used to reduce rotational speed, then the speed reduction function is achieved, but the packaging space increases and mechanical efficiency decreases
Solution Approach 1:
The pericyclic apparatus integrates multiple gear components (pericyclic motion converter, reaction control member, sun gear, planet gears) in a nested configuration where components are arranged concentrically around a central axis. The planet gears rotate around the sun gear while being contained within a housing, creating a compact nested structure that achieves high speed reduction in a small volume.
Solution Approach 2:
The pericyclic mechanism utilizes three-dimensional spatial arrangement with components positioned at different radial distances and angular positions around the central axis. The pericyclic motion converter transforms rotational motion into complex three-dimensional motion paths, allowing multiple gear interactions to occur simultaneously in different spatial planes, thereby achieving high reduction ratios without increasing packaging footprint.
2Speed
If planetary gear sets or multi-gear/stage intermediate shafts are used to reduce rotational speed, then the speed reduction function is achieved, but the number of components increases and mechanical efficiency decreases
Solution Approach 1:
The pericyclic apparatus combines multiple gear functions into a single integrated mechanism. The pericyclic motion converter simultaneously engages with both the sun gear and the reaction control member, creating a unified gear train where components work together in a coordinated manner. This merging reduces the number of separate gear stages and intermediate shafts needed to achieve the same speed reduction.
Solution Approach 2:
The pericyclic motion converter serves multiple functions: it acts as a speed reducer, a motion transformer, and a torque multiplier simultaneously. The reaction control member both controls the pericyclic motion and provides reaction torque support. This multi-functionality eliminates the need for separate components that would otherwise be required to perform these functions individually.
3Speed
If more stages are used to reduce rotational speed, then the speed reduction ratio increases, but power losses increase
Solution Approach 1:
The pericyclic mechanism maintains continuous tooth contact between engaging gears throughout the rotation cycle, ensuring smooth and continuous torque transmission. The planet gears continuously engage with both the sun gear and the reaction control member, eliminating gaps or interruptions in the power transmission path. This continuous action reduces energy losses compared to multi-stage gear systems where torque must be transmitted through multiple discrete gear meshes.
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 pericyclic apparatus provides a compact, lightweight, and efficient speed reduction solution, achieving a high reduction ratio with reduced power losses, enabling efficient torque transfer to the wheels while minimizing space and enhancing mechanical efficiency.
Implementation Method 1
the PMC engages the first gear portion of the output member and the first gear portion of the RCM to rotatably connect the output shaft and the output member
Data Source
AI summary
A speed reduction assembly for an electric vehicle includes an electric machine configured to operate as a motor and as a generator. The electric machine includes an output shaft that is rotatable about a longitudinal axis at an output speed. The assembly also includes an output member coupled to the output shaft and rotatable about the longitudinal axis at a reduced speed. In addition, the assembly includes a pericyclic apparatus coupled to the output shaft and the output member to reduce the output speed of the output shaft to the reduced speed of the output member. A vehicle may include the speed reduction assembly in certain configurations. The vehicle includes a battery module and the electric machine is in electrical communication with the battery module to recharge the battery module when the electric machine operates as the generator.