Planetary Gear Train for 10-Speed Automatic Transmission
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Solution Overview
Problem
Current automatic transmissions with more than eight speeds require multiple planetary gear sets and control elements, increasing complexity, weight, and production costs, while also affecting installability and shift feel.
Innovation Solution
A planetary gear train configuration using four simple planetary gear sets and six control elements, including clutches and brakes, to achieve at least ten forward speeds and one reverse speed, optimizing power delivery and fuel efficiency by minimizing the number of parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of planetary gear sets is increased to achieve more shift stages, then fuel consumption and driving efficiency are improved, but device complexity, weight, and production cost increase
Solution Approach 1:
The patent merges multiple planetary gear sets into a single integrated planetary gear mechanism where the sun gear, planet gears, and ring gear work cooperatively to achieve multiple shift stages (10 forward speeds and 1 reverse speed) without requiring three to four separate planetary gear sets, thereby reducing device complexity while maintaining fuel efficiency
Solution Approach 2:
The planetary gear mechanism is designed with multi-functionality where the same set of gears serves multiple purposes: achieving various gear ratios for different driving conditions, providing both forward and reverse motion, and enabling smooth transitions between shift stages, thereby eliminating the need for additional dedicated gear sets
2Power
If the number of control elements is increased to achieve more shift stages, then power delivery performance is improved, but device complexity and installability are worsened
Solution Approach 1:
Each control element (clutch or brake) in the patent is designed to perform multiple functions: controlling different gear ratios, enabling reverse motion, and facilitating smooth transitions between shift stages. This multi-functionality allows the mechanism to achieve superior power delivery performance with fewer control elements compared to conventional designs
3Productivity
If the total length of transmission is increased to accommodate more planetary gear sets, then more shift stages are achieved, but installability and power flow efficiency are deteriorated
Solution Approach 1:
The patent employs a nested arrangement where planet gears are positioned around the sun gear and engage with the ring gear, creating a compact concentric structure. This nesting allows multiple gear interactions and shift stages to be achieved within a short axial length, improving both installability and power flow efficiency
4Productivity
If plural rows structure is adopted to achieve more shift stages, then fuel consumption is improved, but applicable structure is restricted and shift feel is deteriorated
Solution Approach 1:
The patent segments the control mechanism into independent clutches and brakes that can be selectively engaged or disengaged to achieve different gear ratios. This segmentation provides flexibility in control and maintains good shift feel, while the overall planetary gear structure remains adaptable to different vehicle applications
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 enhances driving stability and fuel efficiency by utilizing low engine rotation speeds, improving power delivery performance and reducing fuel consumption while maintaining minimal complexity and weight.
Implementation Method 1
a first planetary gear set having first, second, and third rotational elements; a second planetary gear set having fourth, fifth, and sixth rotational elements; a third planetary gear set having seventh, eighth, and ninth rotational elements; a fourth planetary gear set having tenth, eleventh, and twelfth rotational elements
Data Source
AI summary
A planetary gear train of an automatic transmission for a vehicle is provided that realizes at least ten forward speeds to improve power delivery performance and fuel consumption due to multi-stages. In particular, the planetary gear train includes 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.