Four Planetary Gearset Transmission for Nine Forward Speeds
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Solution Overview
Problem
Conventional automatic transmissions face challenges in efficiently managing a wide range of vehicle speeds, as many engines operate optimally within a narrow speed range, requiring transmissions that can adapt gear ratios effectively for both low-speed acceleration and high-speed cruising, while also being fuel-efficient.
Innovation Solution
The design incorporates four planetary-gearsets with specific interconnections and shift-elements that allow for the creation of nine forward speeds and one reverse speed, utilizing fixed couplings and selective coupling mechanisms to manage speed ratios through combinations of shift-elements, enabling efficient power transmission across various speed ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmission uses a narrow range of gear ratios, then the structure is simpler, but the engine cannot operate efficiently across a wide range of vehicle speeds
Solution Approach 1:
The transmission is divided into four separate planetary gearsets (first, second, third, and fourth), each capable of providing different speed ratios. By segmenting the transmission into multiple independent planetary gearsets that can be selectively engaged, the system achieves a wide range of speed ratios (nine forward speeds and one reverse speed) while maintaining a modular structure that manages complexity through systematic organization of components
2Productivity
If the transmission has more gear ratios, then engine efficiency across various speeds improves, but the number of shift-elements and control complexity increases
Solution Approach 1:
The planetary gearsets are designed with universal coupling capabilities where gear elements from different planetary gearsets can be interconnected through shift-elements. For example, the carrier of the first planetary gearset can be coupled to the ring gear of the second planetary gearset, and the sun gear of the third planetary gearset can be coupled to the ring gear of the fourth planetary gearset. This multi-functional design allows the same structural elements to serve multiple functions across different gear ratios, reducing the overall number of unique components needed while achieving nine forward speeds and one reverse speed
3Stability of the object's composition
If the transmission uses fixed couplings between planetary gearsets, then the structure is more stable, but the adaptability to different speed requirements decreases
Solution Approach 1:
The transmission employs shift-elements that can dynamically engage and disengage to selectively couple different gear elements of the planetary gearsets. This dynamic configuration allows the transmission to switch between various speed ratios by changing which gear elements are connected. For instance, the shift-elements can selectively couple the carrier of the second planetary gearset to the sun gear of the third planetary gearset, or alternatively couple the ring gear of the fourth planetary gearset to the sun gear of the third planetary gearset, providing adaptive speed ratio adjustment while maintaining structural stability through defined coupling paths
Data Source
AI summary
A four gearing-arrangement transmission having six shift-elements cooperatively engaging in combinations of three to provide nine forward speeds and one reverse speed. The transmission having a first gearing-arrangement with an end-gear fixedly coupled to a ground. A second gearing-arrangement with one end-gear fixedly coupled to an input and the other end-gear fixedly coupled to an interior-gear of the first gearing-arrangement. A third gearing-arrangement having an interior-gear fixedly coupled to an output. A fourth gearing-arrangement having a fourth interior-gear fixedly coupled to the input.