Planetary Gear Train for 11-Speed Automatic Transmission
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Solution Overview
Problem
Conventional automatic transmissions with multiple speed stages face challenges in mountability, increased weight, and manufacturing costs due to the large number of internal components, which affects power transmission efficiency and fuel efficiency.
Innovation Solution
A planetary gear train design that achieves at least eleven forward speed stages and one reverse speed stage using a minimum number of components, incorporating four planetary gear sets and six engaging elements, including clutches and brakes, to optimize power delivery and reduce noise at low engine speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of speed stages is increased to improve fuel efficiency, then fuel efficiency is improved, but the number of internal components increases leading to increased weight, manufacturing cost, and device complexity
Solution Approach 1:
The patent combines multiple planetary gear sets (first, second, third, and fourth planetary gear sets) into a single integrated transmission assembly, where shared components such as the common sun gear, planet gears, and ring gear structure allow multiple speed stages to be achieved without proportionally increasing the number of independent components. This merging approach enables 11 forward speed stages while controlling device complexity.
Solution Approach 2:
The planetary gear sets are designed with multi-functional components that serve multiple purposes. For example, the same planetary gear set can provide both forward speed reduction and reverse speed stages, and certain shafts and gears are used across multiple speed stage configurations. This universality allows a minimum number of components to achieve maximum speed stages.
2Adaptability or versatility
If the number of internal components is increased to achieve more speed stages, then the number of speed stages increases, but mountability is negatively affected due to increased volume and weight
Solution Approach 1:
The patent employs a nested arrangement where planetary gear sets are positioned concentrically around a central input shaft, with each planetary gear set sharing common rotational axes and space. The first, second, third, and fourth planetary gear sets are arranged to overlap and share space, allowing multiple gear trains to be compacted into a smaller overall volume, improving mountability while maintaining 11 forward speed stages.
3Adaptability or versatility
If conventional engaging elements are used to control planetary gear sets, then speed stages can be achieved, but power transmission efficiency is deteriorated
Solution Approach 1:
The patent extracts and eliminates unnecessary intermediate components and redundant engaging elements from the transmission system. By using a minimum number of planetary gear sets with shared components, the design removes excess parts that would otherwise create additional friction points and energy losses, thereby improving power transmission efficiency while maintaining all required speed stages.
Data Source
AI summary
A planetary gear train of an automatic transmission for a vehicle is disclosed and may include: an input shaft receiving torque of an engine; an output shaft outputting torque; a first, second, third and fourth planetary gear set, each having three rotation elements, together first-twelfth rotation elements; a first shaft fixedly connected to a second rotation element and selectively connected to the input shaft; a second shaft fixedly connected to a fourth rotation element and selectively connected to the input shaft; a third shaft fixedly connected to an eighth rotation element and a twelfth rotation element, and fixedly connected to the output shaft; a fourth shaft fixedly connected to a first rotation element, a fifth rotation element, and a ninth rotation element; a fifth shaft connected to a sixth rotation element and an eleventh rotation element; and a plurality of shafts selectively connected to a transmission housing.