Electric Axle Drive Spline Ring Layout for Compact Multi-Ratio Gearing
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Solution Overview
Problem
Existing electric axle drives face challenges in achieving a compact design with minimal axial length while maintaining robust power transmission capabilities and efficiency, particularly due to the need for axial shifting of gear wheels in planetary gear sets.
Innovation Solution
An innovative gear assembly arrangement using planetary gears and pinions that reduces the overall length of the gear assembly, incorporating a spline ring for axial movement control and a disconnect clutch for efficient power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If axial shifting of gear wheels is implemented to achieve multiple gear ratios, then drivability characteristics and energy efficiency are improved, but axial length of the gear assembly increases
Solution Approach 1:
The patent implements a nested planetary gear configuration where a first planetary gear set is positioned within or adjacent to a second planetary gear set, allowing multiple gear ratios to be achieved without increasing axial length. The gear wheels are arranged in a compact, space-efficient manner that enables gear shifting while maintaining a limited axial extent of the entire gear assembly.
Solution Approach 2:
Instead of arranging gear wheels in a linear axial sequence, the patent utilizes radial and circumferential dimensions to position the planetary gear sets. This multi-dimensional arrangement allows gear wheels to be accessed and shifted axially without requiring the entire assembly to extend axially, thereby achieving multiple gear ratios while maintaining a compact axial profile.
2Use of energy by moving object
If axial shifting of gear wheels is implemented to achieve multiple gear ratios, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The patent combines two planetary gear sets into a single integrated gear assembly where components are shared and functions are merged. This consolidation reduces the overall complexity compared to having separate gear sets, while still enabling multiple gear ratios through the coordinated operation of the nested planetary gears.
Solution Approach 2:
The planetary gear sets are designed to serve multiple functions: they provide both gear reduction and multiple gear ratio selection capabilities. The same structural components perform multiple roles, reducing the need for additional specialized parts and simplifying the overall device complexity while maintaining energy efficiency across different operating conditions.
3Length of moving object
If compact gear assembly design is implemented to reduce axial length, then space utilization is improved, but mechanical integrity may be compromised
Solution Approach 1:
The patent employs asymmetric positioning of the planetary gear sets and their components, allowing optimal load distribution and stress management within the compact axial space. The asymmetric arrangement enables mechanical integrity to be maintained by strategically placing stronger components in high-stress areas while keeping the overall axial length limited.
Solution Approach 2:
The gear wheels and planetary components are pre-positioned and pre-loaded during assembly to ensure proper mechanical engagement and load distribution from the outset. This preliminary positioning ensures that even in the compact axial configuration, the mechanical integrity is maintained through optimized stress distribution and proper alignment of load-bearing components.
Data Source
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AI summary
An electric axle drive comprises a gear assembly having a first planetary gear set and a second planetary gear set. The gear assembly further comprises a spline ring that is provided with internal splines along an axial direction of the spline ring and that is slidably provided over ring wheel of the first planetary gear set having mating splines on its outer surface. The spline ring comprises an external groove along its circumference, for receiving a first shift actuator element to shift the spline ring in axial directions over the ring wheel. The spline ring further comprises a first interlock profile on one axial side, that locks the spline ring to a corresponding profile provided onto the stationary housing. The spline ring comprises a second interlock profile on an another axial side, that locks the spline ring, when slid by the actuator element to a corresponding profile provided on the carrier.