Multi-stage Automatic Transmission Gear Train Design
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Solution Overview
Problem
Increasing the number of shift stages in automatic transmissions leads to a higher number of internal components, which worsens vehicle mountability, decreases power transmission efficiency, increases weight, and raises manufacturing costs, while aiming to enhance fuel efficiency and drivability.
Innovation Solution
A multi-stages automatic transmission design utilizing four planetary gear sets and four clutches, with a gear train structure that implements 10 forward speeds and 1 reverse speed, achieving a gear efficiency of 98.6% by minimizing components and optimizing the gear train configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of shift stages is increased to enhance fuel efficiency and drivability, then the number of internal components increases, which worsens vehicle mountability, decreases power transmission efficiency, increases weight, and raises manufacturing costs
Solution Approach 1:
The patent combines multiple planetary gear sets into a unified structure where gear elements are shared across different stages. Specifically, the second planetary gear set's sun gear and carrier are commonly used in multiple gear stages, allowing 10 forward speeds and 1 reverse speed to be achieved with fewer total components than conventional designs would require
Solution Approach 2:
Individual gear elements serve multiple functions across different shift stages. The second sun gear and second carrier act as universal components that participate in multiple gear ratio configurations, enabling a single component to contribute to several different speed stages rather than requiring dedicated components for each stage
2Productivity
If the number of shift stages is increased to enhance fuel efficiency and drivability, then power transmission efficiency decreases due to increased number of internal components
Solution Approach 1:
By merging planetary gear sets and sharing common gear elements (second sun gear, second carrier), the patent reduces the total number of meshing interfaces and friction points. This consolidation minimizes energy losses that would otherwise occur across multiple separate component interfaces, thereby maintaining high power transmission efficiency even with 10 forward speeds
3Productivity
If the number of shift stages is increased to enhance fuel efficiency and drivability, then weight increases due to increased number of internal components
Solution Approach 1:
The patent merges planetary gear sets into a compact configuration where the second planetary gear set serves as a shared foundation for multiple gear stages. This consolidation eliminates the need for separate, redundant components, directly reducing the overall weight of the transmission system while maintaining 10 forward speeds and 1 reverse speed capability
4Productivity
If the number of shift stages is increased to enhance fuel efficiency and drivability, then manufacturing cost increases due to increased number of internal components
Solution Approach 1:
By combining planetary gear sets and identifying commonly used gear elements (second sun gear, second carrier), the patent reduces the total component count that requires manufacturing, assembly, and quality control. This merging strategy directly lowers manufacturing complexity and cost while achieving the target of 10 forward speeds and 1 reverse speed
Data Source
AI summary
A multi-stages automatic transmission for a vehicle may include first, second, third and fourth planetary gear sets each including first, second and third rotation elements, and friction members including first, second, third and fourth clutches and first and second brakes, in which an input shaft may be connected to the second rotation element of the first planetary gear set and the second rotation element of the fourth planetary gear set, and an output shaft may be connected to the second rotation element of the first planetary gear set.