Three-Planetary Transmission Layout for Smooth High-Ratio Shifting
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Solution Overview
Problem
The operational demands for a gearbox in electrically propelled working machines differ significantly from those with conventional internal combustion engines, requiring an improved transmission arrangement to optimize performance in rough terrain environments.
Innovation Solution
A three-stage transmission arrangement using planetary gear sets and locking mechanisms, allowing for rapid and smooth gear shifting with retained power transfer, and enabling large gear ratio steps, which is particularly advantageous for electric prime movers, and can be mechanically connected to two individually controlled prime movers to reduce power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gearboxes are used in electrically propelled working machines, then the transmission arrangement must handle large gear ratio steps, but this leads to increased wear on locking mechanisms and reduced operational performance
Solution Approach 1:
The transmission arrangement is divided into three separate planetary gear sets (first, second, and third planetary gear sets), each capable of independent operation. This segmentation allows the system to achieve large overall gear ratios through combination while each individual gear set handles smaller, more manageable ratio steps, reducing stress and wear on locking mechanisms.
Solution Approach 2:
The gear selection arrangement dynamically engages and disengages different planetary gear sets based on operational requirements. The system can selectively activate specific gear sets to match driving scenarios, optimizing performance while minimizing unnecessary mechanical stress on components.
2Speed
If large gear ratio steps are implemented in a single-stage transmission, then the gear ratio range is sufficient, but the locking mechanisms experience increased wear and reduced durability
Solution Approach 1:
The overall large gear ratio is segmented across three planetary gear sets, with each set contributing a portion of the total ratio. This distribution reduces the gear ratio step each locking mechanism must handle individually, thereby reducing wear and extending durability while maintaining the required overall gear ratio range.
Solution Approach 2:
Each planetary gear set is optimized for its specific function within the overall transmission system. The locking mechanisms are positioned and designed to handle localized gear ratio steps appropriate to their specific gear set, rather than managing the entire gear ratio range in a single location.
3Loss of time
If rapid gear shifting is achieved through locking mechanisms, then the gear changes are fast and smooth, but the locking mechanisms suffer from increased wear
Solution Approach 1:
The gear shifting operation is distributed across three planetary gear sets, each with its own locking mechanism. This segmentation allows the system to achieve rapid gear changes by engaging different gear sets sequentially or in combination, while each individual locking mechanism experiences reduced cyclic stress and wear compared to a single mechanism handling all shifts.
Data Source
AI summary
A transmission arrangement comprises a first planetary gear set, a second planetary gear set, a third planetary gear set, an input shaft connectable to a prime mover, the input shaft being operatively connected to a sun gear of the second planetary gear set and to a sun gear of the third planetary gear set, an output shaft operatively connected to a ring gear of the first planetary gear set and to a planet carrier of the second planetary gear set. The transmission arrangement further includes a gear selection arrangement including a first locking mechanism connected to a planet carrier of the first planetary gear set, a second locking mechanism connected to a sun gear of the first planetary gear set, a ring gear of the second planetary gear set and to a planet carrier of the third planetary gear set, and a third locking mechanism.