Planetary Gear Train Reducing Parts for 10-Speed Transmission
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Solution Overview
Problem
The development of automatic transmissions with increasing shift-stages for improved fuel efficiency and drivability is hindered by the need for more parts, which affects installability, production cost, weight, and power flow efficiency, particularly in eight-speed transmissions that often require multiple planetary gear sets and control elements, leading to weight issues and potential deterioration in shift-feel when using dog clutches.
Innovation Solution
A planetary gear train configuration with three planetary gear sets and six control elements that reduces the number of parts while achieving ten forward speeds and one reverse speed, utilizing a specific arrangement of shafts and clutches to enhance power delivery and engine efficiency, and improve driving stability by optimizing engine rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of planetary gear sets and control elements is increased to achieve more shift-stages, then the fuel efficiency and drivability are improved, but the weight and device complexity increase
Solution Approach 1:
The patent merges multiple planetary gear sets into a unified structure where gear sets share common components. Specifically, the first and second planetary gear sets share a sun gear, and the third and fourth planetary gear sets share a sun gear, reducing the total number of independent parts while maintaining multiple shift stages
Solution Approach 2:
Individual components perform multiple functions across different shift stages. The control elements (clutches and brakes) are designed to engage different combinations of planetary gear elements to achieve various gear ratios, allowing each component to serve multiple purposes rather than requiring dedicated components for each function
2Use of energy by moving object
If the number of planetary gear sets and control elements is increased to achieve more shift-stages, then the fuel efficiency is improved, but the weight increases
Solution Approach 1:
The patent combines multiple planetary gear sets into a compact arrangement where components are shared between gear sets. This merging approach reduces the cumulative weight that would result from having completely separate gear sets for each shift stage
Solution Approach 2:
The planetary gear sets are arranged in a nested configuration where inner and outer gears of different sets interlock and share space. The counter-rotating arrangements allow gear sets to be positioned closely together, effectively nesting functional elements within a compact volume and reducing overall weight
3Weight of moving object
If dog clutches are used instead of wet-type control elements to reduce weight, then the weight is reduced, but the shift-feel deteriorates
Solution Approach 1:
The patent employs control elements that can be replaced or adjusted more easily than traditional wet-type clutches, accepting some wear characteristics in exchange for maintaining acceptable shift quality while reducing overall system weight and complexity
Solution Approach 2:
The design optimizes the engagement characteristics of control elements by adjusting parameters such as engagement force, timing, and sequence to compensate for the inherent limitations of lighter-duty clutches, thereby maintaining acceptable shift-feel despite using lighter components
4Use of energy by moving object
If the number of parts is reduced to improve fuel efficiency, then the fuel consumption is improved, but the installability and manufacturing precision requirements worsen
Solution Approach 1:
By merging planetary gear sets and sharing common components, the patent reduces the total number of parts that need to be manufactured and assembled, thereby reducing cumulative manufacturing precision requirements while maintaining the multi-stage gear reduction capability for improved fuel consumption
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 configuration improves driving stability and fuel efficiency while reducing the number of parts, enhancing power delivery performance and engine efficiency, making it suitable for higher shift-stages without increasing weight or production costs.
Implementation Method 1
a first planetary gear set having a first, a second, and a third rotational elements; a second planetary gear set having a fourth, a fifth, and a sixth rotational elements; a third planetary gear set having a seventh, an eighth, and a ninth rotational elements; a fourth planetary gear set having a tenth, an eleventh, and a twelfth rotational elements
Data Source
AI summary
The present disclosure provides a planetary gear train of an automatic transmission for a vehicle including an input shaft, an output shaft, four planetary gear sets respectively having three rotational elements, and six control elements for selectively interconnecting the rotational elements and a transmission housing.