10-Speed Automatic Transmission Using Nested Planetary Gears
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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 achieve drivability and fuel efficiency competitiveness.
Innovation Solution
Implementing a 10 forward speed and 1 reverse speed automatic transmission using four planetary gear sets, four clutches, and two brakes, optimizing the gear train structure to minimize components and improve fuel efficiency and drivability, particularly by utilizing an operation point in the low RPM range of the engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of shift stages is increased to improve 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 (first, second, third, and fourth planetary gear sets) into a single integrated transmission system where gear stages are achieved through different engagement combinations of clutches and brakes rather than separate component sets. This merging approach enables 10 forward speeds and 1 reverse speed with fewer total components than conventional designs.
Solution Approach 2:
The planetary gear sets and friction elements (clutches C1-C4 and brakes B1-B2) serve multiple functions across different gear stages. For example, the first planetary gear set participates in multiple gear stage combinations, and the same clutches and brakes are reused across different forward and reverse speeds, allowing a single component to perform multiple gear ratio functions.
2Use of energy by moving object
If the number of shift stages is increased to improve fuel efficiency, then the weight of the transmission increases, which worsens vehicle mountability and power transmission efficiency
Solution Approach 1:
Multiple planetary gear sets are merged into a single compact transmission housing with shared components. The first, second, third, and fourth planetary gear sets share common elements including the input shaft, output shaft, and friction elements, reducing overall weight compared to having separate gear train assemblies for each speed stage.
Solution Approach 2:
The planetary gear sets are arranged in a nested configuration where smaller planetary gear sets are positioned within or adjacent to larger ones. The first planetary gear set includes sun gear S1, planet gears P1, and ring gear R1, while subsequent gear sets share spatial overlap and common mounting structures, creating a compact nested arrangement that minimizes weight.
3Adaptability or versatility
If the number of shift stages is increased to achieve 10 forward speeds, then the manufacturing cost increases due to more components, which reduces competitiveness
Solution Approach 1:
The same set of clutches (C1, C2, C3, C4) and brakes (B1, B2) are used to achieve all 10 forward speeds and 1 reverse speed through different engagement combinations. This universal use of friction elements across multiple gear stages significantly reduces the total component count compared to conventional designs that would require separate actuation mechanisms for each speed stage.
Solution Approach 2:
The control system merges multiple gear stage functions into a single coordinated control architecture where the engagement state of four clutches and two brakes determines the current gear stage. This combining approach simplifies the manufacturing and assembly process compared to managing separate control systems for each gear stage.
Data Source
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AI summary
A multi-stages automatic transmission for a vehicle includes a first, second, third and fourth planetary gear sets, each including a first, second and third rotation elements, respectively, and friction members including first, second, third and fourth clutches and first and second brakes.