Three-Position Gear Selection Unit for Multi-Ratio EV Drive
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Solution Overview
Problem
Existing gear reduction units in electric vehicles operate in a single gear state, lacking multiple forward gear states, a reverse gear state, and a neutral gear state, limiting their operational flexibility and efficiency.
Innovation Solution
A gear reduction unit architecture that allows input from a prime mover to be switchable between different gear sets, featuring a dynamically controllable clutch for selective engagement of primary and secondary gear sets, enabling multiple gear ratios and a neutral position, with a torque transfer device for direct or indirect drive modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single gear set is used in the gear reduction unit, then the device complexity is reduced, but the adaptability is limited because multiple gear ratios, reverse direction, and neutral position cannot be achieved
Solution Approach 1:
The gear reduction unit is divided into multiple independent gear sets (first gear set and second gear set), each providing different gear ratios. A gear selection device segments the power flow path to selectively engage either the first gear set for forward motion, the second gear set for reverse motion, or disengage both for neutral position, thereby achieving multiple operational states without requiring a single complex gear mechanism
Solution Approach 2:
The gear reduction unit achieves multi-functionality by incorporating both forward and reverse gear sets along with a neutral position capability. The gear selection device serves multiple functions: selecting between different gear ratios, changing direction of rotation, and providing a neutral state, thereby consolidating what would traditionally require separate mechanisms into a single integrated system
2Adaptability or versatility
If the input shaft rotates in opposite directions to achieve reverse gear, then the gear reduction unit can provide reverse motion, but the reliability decreases due to increased mechanical stress and wear from bidirectional rotation
Solution Approach 1:
Instead of rotating the input shaft in opposite directions to achieve reverse motion, the invention inverts the approach by maintaining unidirectional rotation of the input shaft and using a second gear set with reversed gear arrangement to produce reverse output motion. This keeps the input shaft rotating in a single direction, reducing mechanical stress and improving reliability while still achieving bidirectional output capability
3Productivity
If a gear selection device is added to switch between gear sets, then the productivity is improved through efficient gear ratio selection, but the device complexity increases due to additional clutch mechanisms
Solution Approach 1:
The gear selection device employs dynamically controllable clutch mechanisms that can engage or disengage the first and second gear sets based on operational requirements. This dynamic control allows the system to optimize gear ratio selection in real-time, improving productivity by matching gear ratios to load conditions, while the clutch design is kept compact to minimize the increase in overall device complexity
Data Source
AI summary
A gear reduction unit for coupling the output member of a prime mover to the input member of a device that is to be driven thereby. The gear reduction unit includes an input shaft, an output shaft, a primary gear set arranged between the input shaft and the output shaft, a secondary gear set arranged between the input shaft and the output shaft, and a gear selection device. The gear selection device is configured to selectively and alternately couple the input shaft to the output shaft for driving thereof by one of the primary gear or the secondary gear set.