Planetary Gear Train for Compact Automatic Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing planetary gear trains in automatic transmissions face challenges in mountability, cost, weight, and power delivery efficiency due to the increased number of components required to achieve a greater number of shift speeds, which complicates their integration in front wheel drive vehicles and affects fuel economy.
Innovation Solution
A planetary gear train design that combines three planetary gear sets and five frictional elements with externally-meshing gears to achieve eight forward speeds and one reverse speed, reducing the overall length and improving mountability, while optimizing gear ratios and power delivery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of shift speeds is increased to improve fuel economy, then fuel consumption is reduced, but the number of components increases leading to deteriorated mountability and power delivery efficiency
Solution Approach 1:
The patent combines multiple planetary gear sets (first, second, and third planetary gear sets) into a unified structure where they share common components such as the ring gear, sun gear, and planet carriers. This merging approach allows the transmission to achieve multiple shift speeds (8 forward speeds and 1 reverse speed) without proportionally increasing the number of independent components, thereby improving fuel economy while maintaining reasonable mountability and power delivery efficiency
2Use of energy by moving object
If the number of shift speeds is increased to improve fuel economy, then fuel consumption is reduced, but mountability is deteriorated due to increased component count
Solution Approach 1:
The planetary gear sets are configured to share common components (ring gear, sun gear, planet carriers) to reduce the total number of parts. This consolidation improves mountability by making the transmission more compact and easier to integrate into front wheel drive vehicles, while still achieving 8 forward speeds and 1 reverse speed for improved fuel economy
Solution Approach 2:
Common components such as the ring gear, sun gear, and planet carriers serve multiple functions across different planetary gear sets and different shift speeds. This multi-functionality reduces the overall component count and improves mountability while maintaining the capability to deliver multiple shift speeds for fuel economy improvement
3Use of energy by moving object
If the number of shift speeds is increased to improve fuel economy, then fuel consumption is reduced, but power delivery efficiency is deteriorated
Solution Approach 1:
By merging planetary gear sets with shared components, the patent reduces the number of friction elements and power transmission paths required to achieve multiple shift speeds. This consolidation minimizes energy losses and improves power delivery efficiency while still delivering 8 forward speeds and 1 reverse speed for improved fuel economy
4Adaptability or versatility
If more planetary gear sets are added to achieve more shift speeds, then speed ratios can be more optimally designed, but the length of the transmission increases reducing mountability
Solution Approach 1:
The patent merges multiple planetary gear sets into a compact unified structure where components are shared and space is optimized. This allows for optimal speed ratio design across 8 forward speeds and 1 reverse speed while keeping the transmission length manageable for front wheel drive vehicle integration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances mountability, reduces fuel consumption, and improves power delivery efficiency by minimizing the number of components and optimizing gear ratios, allowing for a more compact and efficient automatic transmission system.
Implementation Method 1
frictional elements selectively interconnecting the rotation elements or selectively connecting the rotation element to a transmission housing
Data Source
AI summary
A planetary gear train of an automatic transmission includes: a first torque-receiving shaft; a second shaft parallel with the first shaft; a first planetary gear set on the first shaft having a first, second and third rotation elements operated as a fixed or output element, directly connected to the first shaft and operated as an input element, and operated as a selective output element, respectively; a compound planetary gear set including a second planetary gear set and a third planetary gear set, and having a fourth, fifth, sixth and seventh rotation elements, selectively connected to the second and third rotation elements, connected to an output gear, selectively connected to the first rotation element, and selectively connected to the third rotation element, respectively; three transfer gears forming externally-meshed gears; and frictional elements selectively interconnecting the rotation elements or selectively connecting the rotation elements to a transmission housing.