Multi-Planetary Gear Transmission for Vehicle Fuel Efficiency
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Solution Overview
Problem
Existing automatic transmissions face challenges in improving fuel efficiency and reducing weight and manufacturing costs while maintaining power transmission efficiency, as increasing the number of shift ranges increases the number of parts, leading to complexity and potential inefficiencies.
Innovation Solution
A transmission system utilizing four planetary gear sets with three rotary elements each, along with a series of clutches and a brake, allowing for selective connection and disconnection of rotary elements to achieve multiple steps of shifting with fewer parts, thereby improving fuel efficiency and driving comfort by utilizing operating points in a low RPM range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of shift ranges is increased to improve fuel efficiency, then fuel efficiency is improved, but the number of parts increases leading to increased device complexity and manufacturing cost
Solution Approach 1:
The patent combines multiple planetary gear sets (first, second, third, and fourth planetary gear sets) into a single integrated transmission system where gear sets share common components such as the input shaft and output shaft. This merging approach enables multiple shift ranges (10+ forward gears and reverse) to be achieved without proportionally increasing the number of independent parts, as each planetary gear set reuses existing rotary elements and friction members.
Solution Approach 2:
Each planetary gear set is designed with universal components that serve multiple functions. The friction members (clutches and brakes) are selectively engaged to achieve different gear ratios and shift ranges. The same planetary gear set can provide both forward motion and reverse motion capabilities, and the input/output shafts serve all gear sets simultaneously, reducing the overall part count while maintaining multiple shift ranges.
2Use of energy by moving object
If the number of shift ranges is increased to improve fuel efficiency, then fuel efficiency is improved, but the manufacturing cost increases
Solution Approach 1:
The transmission system merges multiple planetary gear sets into a compact configuration where components are shared across gear sets. The input shaft connects to multiple planetary gear sets, and the output shaft receives power from multiple gear sets. This consolidation reduces the total number of manufacturing units required compared to having separate gear sets for each shift range, thereby lowering manufacturing costs while achieving 10+ forward gears and reverse.
3Use of energy by moving object
If the number of shift ranges is increased to improve fuel efficiency, then fuel efficiency is improved, but the weight increases
Solution Approach 1:
The planetary gear sets are arranged in a nested configuration where gear sets are positioned concentrically or in overlapping spatial arrangements. The first, second, third, and fourth planetary gear sets share common mounting structures and rotational axes, allowing them to be packed efficiently within a compact volume. This nesting approach minimizes the overall transmission housing size and reduces the weight of supporting structures compared to a linear arrangement of separate gear sets.
4Use of energy by moving object
If the number of shift ranges is increased to improve fuel efficiency, then fuel efficiency is improved, but power transmission efficiency deteriorates
Solution Approach 1:
The planetary gear sets are directly connected through shared rotary elements (input shaft, output shaft, and intermediate planetary carriers) without requiring additional intermediate transmission components. This direct merging minimizes the number of power transmission interfaces and reduces cumulative energy losses. The friction members are designed for efficient engagement with minimal slippage, ensuring that power transmission efficiency is maintained across all 10+ forward gears and reverse.
Data Source
AI summary
A transmission for vehicles may include a first planetary gear set, a second planetary gear set, a third planetary gear set, and a fourth planetary gear set each including three rotary elements, and a plurality of friction members, in which the friction members are connected to at least one or more of the rotary elements of the planetary gear sets and control rotation of the rotary elements.